Compound GW506U78 in refractory hematologic malignancies: relationship between cellular pharmacokinetics and clinical response

PURPOSE

In vitro investigations with arabinosylguanine (ara-G) demonstrated potent cytotoxicity to T-lymphoblastoid cell lines. The goals of the present study were to evaluate GW506U78, a prodrug of ara-G, against human hematologic malignancies and to determine its pharmacokinetics in plasma and cells.

PATIENTS AND METHODS

During a phase I multicenter trial of GW506U78, 26 patients were treated at M.D. Anderson Cancer Center (MDACC). Daily doses between 20 and 60 mg/kg were administered for 5 days. Parallel plasma and cellular pharmacokinetic studies were conducted.

RESULTS

Complete (n=5) or partial remission (n=5) was achieved in T-cell acute lymphoblastic leukemia (T-ALL), T-lymphoid blast crisis, T-lymphoma, and B-cell chronic lymphocytic leukemia (B-CLL) (n=13). In contrast, patients with B-ALL, B-lymphoma, acute myelogenous leukemia (AMI), or T-CLL did not respond. Peak plasma concentrations of GW506U78 and ara-G were dose-dependent. The elimination of GW506U78 (half-life [t1/2]=17 minutes) was faster than the elimination of ara-G (t1/2=3.7 hours). Median peak concentrations of ara-GTP were 23, 42, 85, and 93 micromol/L at 20, 30, 40, and 60 mg/kg, respectively. T-lymphoblasts accumulated significantly (P=.0008) higher peak arabinsylguanosine triphosphate (ara-GTP) (median, 140 micromol/L; n=7) compared with other diagnoses (median, 50 micromol/L; n=9) and normal mononuclear cells (n=3). The ara-GTP elimination was slow in all diagnoses (median, > 24 hours). Responders accumulated significantly (P=.0005) higher levels of ara-GTP (median, 157 micromol/L) compared with patients who failed to respond (median, 44 micromol/L).

CONCLUSION

GW506U78 is an effective prodrug and a potent agent for hematologic malignancies with major efficacy in T-cell diseases. The pharmacokinetics of ara-GTP in leukemia cells are strongly correlated with clinical responses to GW506U78.

Cloning and expression analysis of a novel salicylate suppressible gene, Hs-CUL-3, a member of cullin/Cdc53 family

By using a mRNA differential display technique to search for salicylate suppressible genes, we identified a cDNA in human foreskin fibroblasts, which by GenBankTM DNA data base search shows sequence homology to the recently reported cullin/Cdc53 (CUL) family genes, especially CUL-3. We have cloned the full-length human CUL-3 (Hs-CUL-3) cDNA. It encodes a 768-amino acid polypeptide and has a predicted molecular weight of 88,939. The amino acid sequence of Hs-CUL-3 shows 46% homology to that of its Caenorhabditis elegans ortholog, Ce-CUL-3, and 27 and 23% to that of Hs-CUL-1 and Hs-CUL-2, respectively. Northern blot analysis showed that phorbol 12-myristate 13-acetate increased the expression of Hs-CUL-3 mRNA in a concentration- and time-dependent manner, and this increase was inhibited by sodium salicylate. Hs-CUL-3 widely expressed in human tissues and its expression in cultured COLO205 colon cancer cells was increased when compared with that in normal colon cells. It is likely that Hs-CUL-3 is involved in cell proliferation control.

[Study on the deletion and mutation of p16 gene in human non-small cell lung cancer.]

BACKGROUND

To study the relationship between the deletion and mutation of p16 gene and clinicopathologic manifestations of human non2small cell lung cancer (NSCLC) .

METHODS

Silver staining PCR-SSCP method of control amount of template DNA was used to detect exon 2 of p16 gene in human NSCLC tissue specimens.

RESULTS

The deletion of p16 gene was identified in 13 out of 40 specimens. Of the 40 specimens , 3 showed a variant band indicative of the mutation. There was significant correlation between the frequency of the deletion and mutation (40 %) and clinicopathologic stage ( P < 0. 05) .

CONCLUSIONS

The deletion and mutation of p16 gene may play an important role in carcinogenesis ,development and metastasis of human NSCLC.

A pathological study of in situ thrombosis of small pulmonary arteries and arterioles in autopsy cases of chronic cor pulmonale

OBJECTIVE

To investigate the incidence of in situ thrombosis of small pulmonary arteries and arterioles during the exacerbation stage of chronic cor pulmonale.

METHODS

49 autopsy cases died from the exacerbation of chronic cor pulmonale were chosen as the study group, while 103 other autopsy cases without chronic cor pulmonale and disseminated intravascular coagulation (DIC) as control group. Morphologic and morphometric studies were taken on lung tissues and other organs with focus on the thrombi in small pulmonary arteries and arterioles.

RESULTS

44 cases of the study group had multiple thrombi in small pulmonary arteries and arterioles, the incidence is 89.8%, and in 9 of them, thrombi in proximal pulmonary arteries co-existed, the incidence is 18.4%. 80% of the thrombi existed in pulmonary arterioles. In the control group, only 3 cases had thrombi in small pulmonary arteries and arterioles, the incidence is 2.9%. All thrombi adhered to endangium, implying that they were in situ thrombi. No intravascular thrombosis was found in other organs. chi 2 test showed that the incidence of thrombosis and the number of thrombi in small pulmonary arteries and arterioles in cases with chronic cor pulmonale were significantly higher than those of the control group (P < 0.01).

CONCLUSIONS

Multiple in situ thrombosis in small pulmonary arteries and arterioles is a prominent and common pathological change during the exacerbation stage of chronic cor pulmonale. The study suggests a new diagnostic and therapeutic concept and gives a morphological and theoretical basis for the clinical application of anticoagulants or even the thrombolytic agents for the cases of chronic cor pulmonale in the exacerbation stage.

Lidocaine prolongs the safe duration of circulatory arrest during deep hypothermia in dogs

PURPOSE

To test the hypothesis that lidocaine prolongs the safe period of circulatory arrest during deep hypothermia.

METHODS

Sixteen dogs were subjected to cooling, first surface cooling to 30 degrees C and then core cooling to 20 degrees C rectal temperature). The circulation was then stopped for 90 min. In the lidocaine group, 4 mg.kg-1 lidocaine was injected into the oxygenator two minutes before circulatory arrest and 2 mg.kg-1 at the beginning of reperfusion and rewarming. The control group received equivalent volumes of normal saline. Post-operatively, using a neurological deficit scoring system (maximum deficit score-100; minimum-zero indicating that no scored deficit could be detected). Neurological function was evaluated hourly for six hours and then daily for one week, the pharmacokinetic parameters were calculated using one compartment model.

RESULTS

On the seventh day, the neurological deficit score and overall performance were better in the lidocaine (0.83 +/- 2.04) than in the control group (8.33 +/- 4.08 P < 0.05). During the experiment, the base excess values were also better in the lidocaine than in the control group (at 30 min reperfusion: -4.24 +/- 1.30 vs -8.20 +/- 2.82 P < 0.01, at 60 min reperfusion was -3.34 +/- 1.87 vs -7.52 +/- 2.40 (P < 0.01). On the eighth day the extent of pathological changes were milder in the lidocaine group than that in the control group. The elimination half life of lidocaine was 40.44 +/- 7.99 during hypothermia and 2.01 +/- 4.56 during rewarming.

CONCLUSIONS

In dogs lidocaine prolongs the safe duration of circulatory arrest during hypothermia.

[Host-guest molecule interaction mechanism of hemostatics with liposomes and red blood cells studied with fluorescence polarimetric method]

The supermolecule compounds of adrenobazone, p-aminomethylbenzoic acid, vitamin K1, 6-amino caproic acid with liposomes and red blood cells were studied by fluorescence polarimetric method. The mechanisms of formation of the supermolecule compounds were examined by fluorescence probe of the link of 1,6-dipheny-1,3,5-hexatriene (DPH) with liposomes which were taken as a model of blood cells. The interaction mechanism of hemostatics with red blood cells was described according the quantitative relationship between polarization value (P) and the microviscosity [formula: see text]. The result showed that the acting force between hemostatics and liposomes or that between hemostatics and red blood cells were mainly supermolecular acting force. The acting force between vitamin K1 and cytomembrane is hydrophobic force and those between adrenobazone, p-aminomethylbenzoic acid, or 6-amino caproic acid and cytomembrane are hydrogen bond or electrostatic force. Under the same drug concentration, all of the four haemostatics can reduce the fluidity of the cell membrane, which benefits blood coagulation. The binding ways of hemostatics with red blood cells was also discussed.

[The experimental study of immunization with purified surface protein antigen I/II from streptococcus mutans in BALB/c mice]

OBJECTIVE

To study the immunogenicity and immunoreactivity of purified surface protein antigen I/II from streptococcus mutans.

METHODS

Purified antigen I/II was used to immune BALB/c mice by subcutaneous injection route, and S. mutans whole cells were used as comparison.

RESULTS

ELISA showed immunization with antigen I/II highly induced both specific serum IgG antibody and specific salivary IgA antibody against antigen I/II (P < 0.01), but immunization with whole cells only induced specific serum IgG antibody (P < 0.05).

CONCLUSION

The study suggest purified antigen I/II is an effective candidate vaccine.

Expression of lymphocyte homing receptors and vascular addressins in low-grade gastric B-cell lymphomas of mucosa-associated lymphoid tissue

In this study, we examined lymphocyte homing receptor and vascular addressin expression in a case of primary gastric B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) with a secondary intestinal spread. We compared the findings with that observed in B cells of normal MALT and MALT acquired as a consequence of Helicobacter pylori-associated gastritis and other low-grade gastric B-cell MALT lymphomas. The neoplastic B cells in the gastric tumor were alpha 4 beta 7-, CD62L+, whereas the intestinal secondary was alpha 4 beta 7+, CD62L-. Incubation of isolated tumor cells from the stomach by H. pylori generated T-cell-dependent proliferation of neoplastic B cells and induced expression of alpha 4 beta 7 integrin similar to the intestinal tumor. These observations indicate that reversal of homing receptor profile in the gastric tumor by antigen specific stimulation may be responsible for secondary intestinal dissemination. In normal stomach and normal MALT, alpha 4 beta 7 and CD62L expression reflected the differentiation of the B cell. Plasma cells were alpha 4 beta 7+, CD62L-, whereas a subset of memory B cells were alpha 4 beta 7-, CD62L+. Homing receptor expression in MALT lymphoma B cells was heterogeneous, however, in line with their memory B-cell phenotype in the majority of cases, the neoplastic B cells were alpha 4 beta 7-, CD62L+. Neoplastic plasma cells were always alpha 4 beta 7+, CD62L-. The venules in normal gastric mucosa expressed mucosal addressin cell adhesion molecule-1 but not peripheral lymph node addressin. In normal MALT, H. pylori-associated follicular gastritis and MALT lymphomas high endothelial venules coexpressed mucosal addressin cell adhesion molecule-1 and peripheral lymph node addressin. These findings suggest expression of lymphocyte homing receptors by B cells and vascular addressins by mucosal venules are similar in normal MALT and MALT lymphomas, and factors controlling normal mucosal B-cell traffic are also operational in MALT lymphomas.

[Effect of monaural cochlear ablation on cell areas of ventral cochlear nucleus neurons in neonatal and adult guinea pigs]

The changes of the cross-sectional areas of anteroventral cochlear nucleus (AVCN) and posteroventral cochlear nucleus (PVCN) were studied in neonatal and adult guinea pigs after monaural cochlear ablation with computer imaging analysis system. The cross-sectional areas of neurons in AVCN and PVCN were not significantly changed after 24 h of monaural cochlear ablation in neonatal guinea pigs. But the cell areas of AVCN neurons of ablated side were respectively reduced by 20.93%, 25.70% and 28.72% compared to non-ablated side in 4 d, 7 d, 60 d after cochlear ablation, the cell areas of PVCN neurons were reduced by 17.58%, 20.30% and 38.55% respectively. The area reduction of AVCN and PVCN neurons of ablated side in 60 d group with monaural cochlear ablation were 51.00% and 32.75% relative to normal control group. Our results showed that cochlear ablation could results in rapid cell area reduction of VCN neurons in guinea pigs. Our investigation implied that it is important to stimulate the auditory nerve early in the patients with hearing loss.

Minimum dose of fludarabine for the maximal modulation of 1-beta-D-arabinofuranosylcytosine triphosphate in human leukemia blasts during therapy

1-beta-d-Arabinofuranosylcytosine (ara-C), an effective drug for acute leukemias, must be phosphorylated to its 5'-triphosphate, ara-CTP, for activity. Our previous studies during therapy of acute myelogenous leukemia (AML) patients demonstrated that the accumulation of ara-CTP in circulating leukemia blasts was increased by a median of 2-fold when fludarabine (30 mg/m2/day over 30 min) was infused 4 h prior to intermediate dose ara-C. The augmentation was dependent on the cellular concentration of fludarabine triphosphate (F-ara-ATP). To determine the lowest dose of fludarabine needed for modulation of ara-C metabolism, the present study administered fludarabine at a test dose (15 mg/m2 over 30 min) followed by 2 g/m2 ara-C infused over 4 h. The next day, the fludarabine/ara-C couplet was repeated but with a standard dose (30 mg/m2) of fludarabine. There was a dose-dependent accumulation of F-ara-ATP in circulating leukemia blasts; the median peak concentrations were 33 and 41 microM with 15 and 30 mg/m2 of fludarabine, respectively. These intracellular levels of F-ara-ATP effectively increased ara-CTP accumulation to similar levels. To further titrate the dose of fludarabine, the next cohort of patients (n = 4) initially received fludarabine test doses of 7.5 or 5 mg/m2, followed by the 30 mg/m2 dose of fludarabine on the next day; each dose was infused 4 h prior to 2 g/m2 of ara-C. The peak levels of F-ara-ATP at 7.5 and 5 mg/m2 fludarabine were between 3 and 39 microM. The AML blasts that achieved >/=10 microM intracellular F-ara-ATP accumulated ara-CTP similar to the levels achieved after 30 mg/m2 of fludarabine. However, <10 microM intracellular F-ara-ATP resulted in less ara-CTP accumulation compared to that observed after the conventional dose of fludarabine. These data suggest that the modulation of the ara-CTP accumulation by fludarabine is dependent on the cellular concentration of F-ara-ATP, and that 15 mg/m2 fludarabine infused over 30 min consistently produces cellular F-ara-ATP levels that maximize ara-CTP accumulation in AML blasts. These findings point to the feasibility of intensifying the fludarabine-ara-C regimen by using fludarabine as a 15 mg/m2/dose twice daily with intermediate-dose ara-C.

[Simultaneous determination of tyrosine and tryptophan in amino acid injection, animal and plant extracts by polarization spectrofluorimetry]

A new method for the simultaneous determination of tyrosine and tryptophan by polarization spectrofluorimetry has been developed. The interference of phenylalanine and light scattering of solvent were eliminated by using vertically crossed polarizers. The overlapping of fluorescence spectra of the two amino acids was solved with filters. The linear ranges of determination were 0.02-12.0 mg.L-1(tyrosine) and 0.01-2.50 mg.L-1(tryptophan). The mean recoveries of tyrosine and tryptophan in samples were 95.4% and 101.7% (in amino acid injection). 99.2% and 100.0% (in wild jujube kernel), 95.3% and 97.2% (in shrimp shell) respectively. The proposed method has been used to determine tyrosine and tryptophan in amino acid injection, extracts of wild jujube kernel and shrimp shells with satisfactory results.

Identification of alternative first exons of NADH-cytochrome b5 reductase gene expressed ubiquitously in human cells

Two forms of NADH-cytochrome b5 reductase (b5R), soluble and membrane-bound, are known. A hypothesis that the human soluble form b5R is generated through post-translational processing of the membrane-bound form was previously proposed. In this study, the 5'-rapid amplification of cDNA ends for human reticulocyte, liver, brain, and HL-60 cell mRNAs revealed the ubiquitous presence of an alternative type of human b5R mRNA which can probably be translated into the soluble form b5R directly; however, the erythroid-specific transcript of the b5R gene was not found. This type of b5R mRNA initiating from at least two sites contains a non-coding new first exon located between the first two exons of the human b5R gene identified before. In addition, this new first exon shares 62% homology with the first exon and its 3'-flanking intron sequences of rat erythroid-specific b5R mRNA, whereas the 5'-flanking region of the new first exon possesses features of house-keeping gene. These results might be important to understand the regulation mechanism of human b5R biosynthesis and divergent evolution of the gene regulation.

Genetic evidence for a clonal link between low and high-grade components in gastric MALT B-cell lymphoma

High-grade MALT lymphomas often contain low-grade tumour components; both cell populations have been shown to express the same immunoglobulin light chain previously. However, the clonal link between the low and high-grade components has not been established at the genetic level. To investigate this link, we have examined low- and high-grade components micro-dissected from tissue sections of four high-grade gastric MALT lymphomas. PCR and sequence analyses were performed to identify clone-specific rearranged immunoglobulin heavy chain gene sequences. In each of these cases, the PCR products from the two components were identical in size by electrophoresis. Direct sequencing revealed common clone-specific immunoglobulin heavy chain gene rearrangements in both lesions of each case, providing genetic evidence for a clonal link. These results support the proposal that high-grade MALT lymphomas generally evolve from low-grade clones.

Contraceptives for lactating women: a comparative trial of a progesterone-releasing vaginal ring and the copper T 380A IUD

From approximately one week before normal ovulation resumes, lactating women require protection against pregnancy by a contraceptive that is safe for both infant and mother in a multicenter one-year study, the natural hormone, progesterone, delivered vaginally by a sequence of four contraceptive rings designed for continuous use, was evaluated as a contraceptive for nursing mothers in comparison with the Copper T 380A IUD. Individual rings release in effective average dose of 10 mg day for a 3 month period. Evaluation included measures of lactational performance as well as of contraceptive efficacy and safety to mother and child. Nine participating clinics enrolled 802 ring users and 734 IUD acceptors between postpartum days 29 and 63. Life table analyses were performed with parallel decrements for ring and IUD subjects. Continuation in the study and analysis required that subjects not stop breastfeeding. The ring, with a one-year pregnancy rate of 1.5 per 100, did not differ significantly from the IUD with respect to contraceptive effectiveness (p > 0.05). More than half of the ring subjects were continuing at 6 months post admission and a quarter (23.5 per hundred) were still using the ring and breastfeeding one year after admission. Women with the IUD, however, had higher continuation rates (p < 0.001) at both time points. The largest single decrement for each method was that for weaning. Ring users had more complaints of vaginal problems but had fewer vaginal disorders on examination. At 12 months postpartum, 46 per 100 continuing ring users remained in amenorrhea. Lactation performance and the health and weight gain of the infants were similar among users of either regimen.

Promotion of proliferation of murine BALB/C3T3 fibroblasts mediated by nitric oxide at lower concentrations

This study showed that nitric oxide (NO)-generating S-nitrosothiols, S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO), increased proliferation of BALB/c 3T3 (clone A31-1-1) fibroblasts in vitro. Treatment with SNAP at a relatively low concentration (0.005-0.02 mM) induced an increase in cell number compared to control. SNAP (0.005-0.02 mM) and GSNO (0.025-0.05 mM) both showed an increase of [3H]thymidine incorporation in exponentially growing cells in a dose-dependent manner. The maximal effect was observed at about 40 and 90% above control at 0.02 mM and 0.05 mM, respectively. The increase induced by 0.02 mM SNAP was abolished by the addition of 0.01 mM oxyhemoglobin, a scavenger of NO. [3H]Thymidine incorporation in stationary cells was also increased by SNAP. In addition, 0.02 mM SNAP produced a 1.8-3.2-fold increase of thymidine kinase activity in exponentially growing cells.

[A pathological study of in situ thrombosis of small pulmonary arteries and arterioles in autopsy cases of chronic cor pulmonale]

OBJECTIVE

To study the incidence of thrombosis of small pulmonary arteries and arterioles during the exacerbation stage of chronic cor pulmonale.

METHODS

49 autopsy cases died from the exacerbation of chronic cor pulmonale were chosen as the study group, while other 103 autopsy cases without chronic cor pulmonale and disseminated intravascular coagulation (DIC) as control group. Morphologic and morphometric studies were taken on lung tissues and other organs with focus on the thrombi in small pulmonary arteries and arterioles.

RESULTS

44 cases of the study group had multiple thrombi in small pulmonary arteries and arterioles, the incidence is 89.8%, and in 9 of them, thrombi in proximal pulmonary arteries co-existed, the incidence is 18.4%, 80% of the thrombi existed in pulmonary arteriole. In control group, only 3 cases had thrombi in small pulmonary arteries and arteriole, the incidence is 2.9%. All thrombi adhered to endangium, implying that they were in situ thrombi. No intravascular thrombosis were found in other organs. chi(2) test showed that the incidence of thrombosis and the number of thrombi in small pulmonary arteries and arteriole in cases with chronic cor pulmonale were significantly higher than that of the control group (P < 0.01).

CONCLUSIONS

Multiple in situ thrombosis in small pulmonary arteries and arterioles is a prominent and common pathological change during the exacerbation stage of chronic cor pulmonale. The study suggests a new diagnostic and therapeutic concept and provides a morphological and theoretical basis for the clinical application of anticoagulants or even the thrombolytic agents for the cases of chronic cor pulmonale in the exacerbation stage.

Clonality analysis in tumours of women by PCR amplification of X-linked genes

Modifications have been made to two polymerase chain reaction (PCR) methods for clonality analysis based on the inactivation patterns of two highly polymorphic X-linked genes encoding the androgen receptor (AR) and monoamine oxidase A (MAOA). These methods have been used to examine the clonal nature of frozen tissues from 42 tumours and 25 non-tumour controls from female subjects. Unbalanced inactivation patterns of the genes, which indicate monoclonality, were frequently observed in tumours of heterozygous (informative) cases (18/35 = 51.4 per cent for the AR gene, 9/30 = 30 per cent for the MAOA gene, and 21/38 = 55.2 per cent for both). Among 23 informative non-tumour controls, only one (4.3 per cent), a reactive lymph node, showed skewing in the AR gene. Successful detection of monoclonality was found to depend on the proportion of tumour cells in the tissues examined. None of the AR or MAOA informative cases containing less than 50 per cent of tumour cells showed imbalance in inactivation patterns. With more than 50 per cent of tumour cells in the samples, 66.6 per cent (18/27) of AR and 39.1 per cent (9/23) of MAOA informative cases showed allelic imbalance, with a combined frequency of 72.4 per cent (21/29) of both genes. Our results demonstrate that the methods described are useful for clonal analysis of tissue samples from female patients.

[Location of the surface protein antigen I/II on Mutans Streptococci with immunogold electron microscope]

Mutans Streptococci possess a number of surface protein antigens. The surface protein antigen I/II with a molecular mass of 190,000 is considered to play an important role in the initial attachment to tooth surface. The antigen is highly immunogenic and has been successfully used as a vaccine against dental caries. The object of this study is to locate the surface protein antigen I/II of Mutans Streptococci with immunogold electron microscope. The results suggest that (1) antigen I/II locate on the cell wall surface of serotype c, e, f; (2) antigen I/II locate on the "fuzz coat" of the cell wall of serotype d, g; (3) some antigen I/II locate at the surface of cell wall of serotype a; (4) antigen I/II are absent on the cell wall surface of serotype b strain.

Positive correlation between apoptotic and proliferative indices in gastrointestinal lymphomas of mucosa-associated lymphoid tissue (MALT)

To understand the role of deregulation of apoptosis in the pathogenesis of gastrointestinal MALT lymphoma, apoptosis has been quantitatively studied in paraffin sections from 40 cases (19 low grade, 21 high grade). The extent of apoptosis was correlated with histological grade, proliferative activity as measured by immunostaining of Ki67 proliferation antigen, and the expression of bcl-2 and p53 oncoproteins, which are known to participate in the regulation of apoptosis. Both apoptotic and proliferative indices were significantly (P < 0.00001) higher in high-grade than in low-grade tumours. Overall, apoptotic indices were negatively correlated with bcl-2 expression, particularly in low-grade tumours in which both strong bcl-2 expression and low levels of apoptosis were observed. Thus, the slow expansion of low-grade MALT lymphoma may partly result from a prolonged life-span of tumour cells, due to bcl-2-mediated blockage of apoptosis. No difference in apoptotic indices was found between p53-positive and p53-negative cases. Furthermore, correlation analysis revealed a significantly positive association between apoptotic and proliferative indices. This supports the current belief that the mechanisms controlling apoptosis and proliferation are both activated during the cell cycle and whether a cell enters the proliferation cycle or the apoptotic process depends on survival factors.

Ongoing mutation in MALT lymphoma immunoglobulin gene suggests that antigen stimulation plays a role in the clonal expansion

Indirect antigenic stimulation by H. pylori-specific T cells is implicated in the development of low-grade gastric lymphoma of mucosa-associated lymphoid tissue (MALT), however, the role of direct antigen stimulation is unknown. To study the role of direct antigen stimulation in MALT lymphomagenesis and its relationship with the pathogenesis of distinct pathological lesions, which represent different stages of the tumour progression, we cloned and sequenced the rearranged immunoglobulin (Ig) heavy chain gene in three low-grade (two from the lung, one from the stomach) and one high-grade (from the stomach) cases. In the low-grade gastric case, we studied the Ig sequence in primary as well as its disseminated and recurrent tumours. In the high-grade gastric case, we analysed the Ig sequence in tumour cell populations microdissected from the residual diffuse low-grade lesions, diffuse high-grade areas from follicles colonized by high-grade blasts. Compared with the published germline sequences, the heavy chain variable (VH) genes of three MALT lymphomas, in which the putative germline was identified, contained frequent somatic mutations, showing a much higher ratio of replacement/silent mutations in the complementarity determining regions (CDRs) than the framework regions (FRs). Ongoing mutation as indicated by intraclonal variation of the Ig sequence clearly existed in low-grade tumour including its dissemination and recurrence, but was not evident in high-grade tumour cell populations including those microdissected from independent colonized follicles. In addition, the germlines of VH genes used by the three MALT lymphomas are frequently found in autoreactive antibodies. Our results suggest that MALT lymphoma derives from postgerminal centre memory B cells, possibly autoreactive B cell clones, and that direct antigen stimulation may play an important role in the clonal expansion of low-grade MALT lymphoma.

Recognition of beta-D-Gal p-(1-->3)-beta-D-Glc pNAc-OR acceptor analogues by the Lewis alpha-(1-->3/4)-fucosyltransferase from human milk

The Lewis alpha-(1-->3/4)-fucosyltransferase (E.C. 2.4.1.65) transfers L-fucose from GDP-fucose to OH-4 of the Glc pNAc residue in the disaccharide beta-D-Galp-(1-->3)-beta-D-Glc pNAc-OR [R = (CH2)8COOMe] (1) to give the Lewis-A blood group determinant beta-D-Gal p-(1-->3)-[alpha-L-Fuc p-(1-->4)]-beta-D-Glc pNAc-OR. Five deoxy analogous of 1, as well as its N-propionyl derivative, were chemically synthesized and kinetically evaluated as both substrates and inhibitors for the enzyme from human milk. The unmodified acceptor 1 had Km = 640 microM with Vmax set arbitrarily to 100. The 6-deoxy (Km = 400 microM, V(max) = 90) and N-propionyl compounds (Km = 330 microM, V(max) = 170) remained excellent substrates while the 4-deoxy compound was a very weak competitive inhibitor with Ki = 9 mM. Deoxygenation of OH-2' and OH-4'(of the Gal residue) in 1 had little effect on the activity. The OH-6 group of the Gal residue proved to be critical for recognition by the enzyme since substitution of this group with hydrogen led to an inactive compound.

Positive correlation between apoptotic and proliferative indices in gastrointestinal lymphomas of mucosa-associated lymphoid tissue (MALT)

To understand the role of deregulation of apoptosis in the pathogenesis of gastrointestinal MALT lymphoma, apoptosis has been quantitatively studied in paraffin sections from 40 cases (19 low grade, 21 high grade). The extent of apoptosis was correlated with histological grade, proliferative activity as measured by immunostaining of Ki67 proliferation antigen, and the expression of bcl-2 and p53 oncoproteins, which are known to participate in the regulation of apoptosis. Both apoptotic and proliferative indices were significantly (P < 0.00001) higher in high-grade than in low-grade tumours. Overall, apoptotic indices were negatively correlated with bcl-2 expression, particularly in low-grade tumours in which both strong bcl-2 expression and low levels of apoptosis were observed. Thus, the slow expansion of low-grade MALT lymphoma may partly result from a prolonged life-span of tumour cells, due to bcl-2-mediated blockage of apoptosis. No difference in apoptotic indices was found between p53-positive and p53-negative cases. Furthermore, correlation analysis revealed a significantly positive association between apoptotic and proliferative indices. This supports the current belief that the mechanisms controlling apoptosis and proliferation are both activated during the cell cycle and whether a cell enters the proliferation cycle or the apoptotic process depends on survival factors.

Replication error phenotype and p53 gene mutation in lymphomas of mucosa-associated lymphoid tissue

Low grade mucosa-associated lymphoid tissue (MALT) lymphomas commonly arise from a background of chronic inflammatory lesions and can transform into high grade tumors at a late stage. Because chronic inflammation is closely associated with genetic instability, which is one of the mechanisms leading to activation of oncogenes and inactivation of tumor suppressor genes, it is possible that genetic instability plays an important role in MALT lymphomagenesis. In this study, we have examined the frequency of replication error (RER+) phenotype, a newly defined manifestation of genetic instability, and its relationship to p53 mutations in 40 MALT lymphomas (16 high grade and 24 low grade). RER+ phenotype was detected in 21/40 (52.5%) MALT lymphomas (12/24, 50% in low grade; 9/16, 56.2% in high grade). Five of seven reactive lymphoid infiltrates adjacent to tumors also showed one microsatellite alteration, four of which were identified in the corresponding lymphoma lesions in the same patient. In five RER+ high grade lymphomas with low grade lesions, homogeneous and heterogeneous microsatellite alterations were observed between the two components. The same 40 cases were investigated for p53 gene mutations at exons 5 to 8 by PCR-SSCP and direct sequencing. p53 point mutations were found in 11 (27.5%) of the 40 cases. These mutations were statistically related to RER+ phenotype (P < 0.05). Our results demonstrate that the RER+ phenotype is a common genetic feature of MALT lymphomas. Genetic instability occurs throughout the spectrum of the lymphoma development and may be related to the accumulation of genetic aberrations such as p53 mutations. The observation of identical microsatellite alterations between the adjacent lymphoid infiltrates and their corresponding lymphomas provides genetic evidence for evolutionary link of the two lesions. The homogeneous and heterogeneous microsatellite alterations observed between low and high grade components indicate their clonal lineage and genetic diversity.

The accumulation of p53 abnormalities is associated with progression of mucosa-associated lymphoid tissue lymphoma

The genetic mechanisms underlying the genesis of low-grade mucosa-associated lymphoid tissue (MALT) lymphomas and their transformation into high-grade lymphoma are poorly understood. p53 inactivation, commonly caused by mutation and allele loss, has been shown to play an important role in the early development and/or the late disease progression of many human tumors including lymphoid malignancies and, thus, may also be important in MALT lymphomagenesis. We examined 75 cases (48 low grade and 27 high grade) of MALT lymphoma for p53 allele loss and mutation as well as protein accumulation. DNA samples prepared from microdissected cell populations were used for the detection of p53 gene abnormalities. Loss of heterozygosity (LOH) of the gene was detected by polymerase chain reaction-based analysis of p53 CA repeat polymorphism, whereas p53 mutation was studied by single-strand conformation polymorphism analysis and direct sequencing. p53 expression was assessed by immunostaining with CM1 polyclonal antibody. p53 allele loss and mutation, which resulted in the alteration in the amino acid sequence, were found in both low-grade (LOH, 3 of 44 [6.8%]; mutation, 9 of 48 [18.8%]) and high-grade (LOH, 6 of 21 [28.6%]; mutation, 9 of 27 [33.3%]) MALT lymphomas, particularly in the latter group. p53 staining was not observed in any low-grade tumors but in 6 high-grade cases that harbored missense mutations. There were also differences in the extent of p53 abnormalities, between low- and high-grade tumors. Of the 11 low-grade tumors showing p53 abnormalities, only 1 tumor showed the concomitance of p53 mutation and allele loss, whereas in high-grade tumors, 6 of 9 affected cases displayed both p53 mutation and allele loss. Our results suggest that p53 partial inactivation may play an important role in the development of low-grade MALT lymphomas, whereas complete inactivation may be associated with high-grade transformation.

Dosimetric evaluation of the conformation of the multileaf collimator to irregularly shaped fields

PURPOSE

The goal of this study was to evaluate the dosimetric characteristics of geometric MLC prescription strategies and compare them to those of conventional shielding block.

METHODS AND MATERIALS

Circular fields, square fields, and 12 irregular fields for patients with cancer of the head and neck, lung, and pelvis were included in this study. All fields were shaped using the MLC and conventional blocks. A geometric criterion was defined as the amount of area discrepancy between the MLC and the prescription outline. The "least area discrepancy" (LAD) of the MLC conformation was searched by selecting the collimator angle, meanwhile keeping a preselected position along the width of the leaf into the prescribed field. Five LAD conventions were studied. These included the LAD-0, LAD-1/3, LAD-1/2, and LAD-2/3 that inserted the leaves at the 0, 1/3, 1/2, and 2/3 of the leaf end into the prescription field, respectively. In addition, the LAD optimization was applied to the transecting (TRN) approach for leaf conformation that prescribed an equal area of overblocking and underblocking under each leaf. Film dosimetry was performed in a 20 cm polystyrene phantom at 10 cm depth 100 cm from source to axis distance (SAD) for both 6 and 18 MV photons with each of the above MLC conformations and conventional blocks. The field penumbra width, defined as the mean of the separation between the 20% and 80% isodose lines along the normal of the prescription field edge, was calculated using both the MLC and conventional block film dosimetry and compared. In a similar way, the d20 is defined as the mean separation between the 20% isodose line and the prescription field edge, and the d80 is defined as the mean separation between the 80% isodose line and the prescription field edge.

RESULTS

The field penumbra width for all MLC conventions was approximately 2 mm larger than that of the conventional block. However, there was a larger variation of the separation distribution in the penumbra region of the irregular fields for the MLC, which had a standard deviation of 1 mm (a factor of 5 larger than the conventional block). The dosimetry for the circular fields showed that the LAD-TRN, LAD-1/2, and LAD-1/3 approximated the conventional blocking well in terms of d20 and d80; however, no single convention produced the best conformation for both measures. The dosimetric result of the patient treatment fields was similar for all sites. The LAD-1/3, LAD-1/2, and LAD-TRN strategies conformed to within 1 to 1.5 mm of the d80 of the conventional block for both 6 MV and 18 MV, respectively. The LAD-1/2 and LAD-TRN conformations were virtually identical, although it is proven analytically that the LAD-1/2 convention has the least overall area discrepancy of all conventions.

CONCLUSIONS

The five MLC conformation conventions resulted in similar dosimetric penumbrae for all field shapes studied. The LAD-1/3, LAD-TRN, and LAD-1/2 produced the more favorable approximation to conventional block. The field penumbra width, although useful for evaluating irregular field shapes, could not describe the large local variations in the penumbra along the field edge for the MLC. These local variations could be of clinical concern when they appear near vital organs. However, the variation in a local region can potentially be reduced by minimizing the jaggedness of the leaf steps in that local region. The dosimetric results were useful as guidelines for the clinicians in the evaluation and adjustment of MLC leaf positions.