The relaxation responses to corticotropin-releasing factor in rat aorta are endothelium dependent and gestationally regulated

OBJECTIVE

Our purpose was to examine the hypothesis that the relaxant response to corticotropin-releasing factor is endothelium dependent and changes during pregnancy.

STUDY DESIGN

Relaxant responses to cumulative concentrations of corticotropin-releasing hormone were measured in rings of thoracic aorta, precontracted with phenylephrine, from pregnant and nonpregnant female rats. Each group consisted of 5 to 10 rats.

RESULTS

The relaxation induced by corticotropin-releasing factor in aortic rings from nonpregnant rats decreased after deendothelization and treatment with N omega-nitro-L-arginine methyl ester (a nitric oxide synthase inhibitor), LY-83,583 (a guanylate cyclase inhibitor), or alpha-helical corticotropin-releasing factor 9-41 (a corticotropin-releasing factor antagonist). The percent decrease in relaxation at 1 nmol/L of corticotropin-releasing factor was about 88% with deendothelization, 100% with N omega-nitro-L-arginine methyl ester, 76% with LY-83,583, and 100% with alpha-helical corticotropin-releasing factor 9-41. The responses to corticotropin-releasing factor in intact rings from rats in early pregnancy were not significantly different from those in the nonpregnant female rats, but the responses were decreased during the later stages of gestation (percent decrease in relaxation at 1 nmol/L of corticotropin-releasing factor about 71% at day 20 and 98% at term). The relaxation induced by corticotropin-releasing factor during pregnancy was also inhibited by deendothelization, N omega-nitro-L-arginine methyl ester, or LY-83,583.

CONCLUSIONS

The relaxant response to corticotropin-releasing factor in the rat aorta is endothelium dependent and is mediated by the nitric oxide-cyclic guanosine monophosphate pathway. The receptor involved in this effect is alpha-helical corticotropin-releasing factor 9-41 sensitive. This inhibitory response is unchanged during early pregnancy but reduced toward the end of gestation.

Isolation of angiopoietin-1, a ligand for the TIE2 receptor, by secretion-trap expression cloning

TIE2 is a receptor-like tyrosine kinase expressed almost exclusively in endothelial cells and early hemopoietic cells and required for the normal development of vascular structures during embryogenesis. We report the identification of a secreted ligand for TIE2, termed Angiopoietin-1, using a novel expression cloning technique that involves intracellular trapping and detection of the ligand in COS cells. The structure of Angiopoietin-1 differs from that of known angiogenic factors or other ligands for receptor tyrosine kinases. Although Angiopoietin-1 binds and induces the tyrosine phosphorylation of TIE2, it does not directly promote the growth of cultured endothelial cells. However, its expression in close proximity with developing blood vessels implicates Angiopoietin-1 in endothelial developmental processes.

Radioprotective effects of diltiazem on cytogenetic damage and survival in gamma ray exposed mice

Diltiazem, a calcium ion channel blocker, already in use in cardiovascular therapeutics, has been observed to protect against bone marrow damage (cytogenetic damage, cell death) and mortality in whole body irradiated mice. The micronuclei fraction in bone marrow cells of whole body irradiated (60Co gamma rays, 2.0 Gy) mice was reduced from 2.24 +/- 0.23% to about 0.74 +/- 0.33% by preirradiation administration (-20 min) of 110 mg/kg body wt. diltiazem (ip). Endogenous colony forming unit counts in spleen of mice administered 110 mg/kg body wt. (-20 min) of diltiazem before 10 Gy whole body irradiation were 6 times more than untreated irradiated controls. Pretreatment with diltiazem accelerated the recovery of radiation induced weight loss also. Diltiazem (110 mg/kg body wt, -20 min) enhanced 30 day survival to about 95% and 85% after lethal whole body absorbed dose of 9 and 10 Gy respectively and also mitigated radiation induced life- span shortening. Post-irradiation (10 Gy) administration of diltiazem (+20 to 30 min) enhanced survival from about 2 to 15% only but was highly significant (P < 0.001). Possible modes of radioprotective action of diltiazem have been discussed.

A phase I study of bolus versus continuous infusion of the anti-CD19 immunotoxin, IgG-HD37-dgA, in patients with B-cell lymphoma

IgG-HD37-SMPT-dgA is a deglycosylated ricin A chain (dgA)-containing immunotoxin (IT) prepared by conjugating the monoclonal murine (MoAb) anti-CD19 antibody, HD37, to dgA using the heterobifunctional hindered disulfide linker, N-succinimidyl-oxycarbonyl-alpha-methyl-alpha-(2-pyridyldithio) toluene (SMPT). In this report, we have used two regimens for the administration of IgG-HD37-SMPT-dgA to patients with non-Hodgkin's lymphoma (NHL) in two concomitant phase I trials. One trial examined four intermittent bolus infusions administered at 48-hour intervals. The other studied a continuous infusion (CI) administered over the same 8-day period. In the intermittent bolus regimen, the maximum tolerated dose (MTD) was 16 mg/m2/8 d and the dose-limiting toxicity (DLT) consisted of vascular leak syndrome (VLS), aphasia, and evidence of rhabdomyolysis encountered at 24 mg/m2/8 d. Using the CI regimen, the MTD was defined by VLS at 19.2 mg/m2/8 d. At the MTD of both regimens, a novel toxicity, consisting of acrocyanosis with reversible superficial distal digital skin necrosis in the absence of overt evidence of systemic vasculitis, occurred in 3 patients. Of 23 evaluable patients on the bolus schedule, there was 1 persisting complete response (CR; > 40 months) and 1 partial response (PR). Of 9 evaluable patients on the continuous infusion regimen, there was 1 PR. Pharmacokinetic parameters for the bolus regimen at the MTD showed a mean maximum serum concentration (Cmax) of 1,209 +/- 430 ng/mL, with a median T1/2 beta for all courses of 18.2 hours (range, 10.0 to 80.0 hours), a volume of distribution (Vd) of 10.9 L (range, 3.1 to 34.5 L), and a clearance (CL) of 0.45 L/h (range, 0.13 to 2.3 L/h). For the CI regimen at MTD, the mean Cmax was 963 +/- 473 ng/mL, with a median T1/2 beta for all courses of 22.8 hours (range, 24.1 to 30.6 hours), a Vd of 9.4 L (range, 4.4 to 19.5 L), and a CL of 0.32 L/h (range, 0.12 to 0.55 L/h). Twenty-five percent of the patients on the bolus infusion regimen and 30% on the CI regimen made antibody against mouse Ig (HAMA) and/or ricin A chain antibody (HARA). We conclude that this IT can be administered safely and that both regimens achieve comparable peak serum concentrations at the MTD; these concentrations are similar to those achieved previously using other regimens with IgG-dgA ITs at their respective MTDs. Thus, toxicity is related to the serum level of the IT and does not differ with different targeting MoAbs.

Differential regulation of nitric oxide in the rat uterus and cervix during pregnancy and labour

The aim of this study was to determine if nitric oxide (NO) production and nitric oxide synthase (NOS) isoforms change within the uterus and cervix during pregnancy and labour either at term or preterm. NO production was compared in the rat uterus and cervix of non-pregnant and pregnant rats on days 18-22 prior to labour, day 22 during delivery, 1 day post-partum and after treatment with either 10 mg onapristone or progesterone. Uterine NO synthesis, reflected in nitrite production, increased during gestation (194.2 +/- 22.6 nmol/g on day 19) compared with the non-pregnant state (76.2 +/- 18.4 nmol/g, P < 0.05) and decreased during term labour and post-partum. Furthermore, injection of lipopolysaccharide (LPS) (100 micrograms/rat i.p.) on day 20 of gestation resulted in a significant increase in NO synthesis after 6 h. Conversely, cervical NO synthesis and nitrite production was low in the non-pregnant (65.1 +/- 9.2 nmol/g) and pregnant animals on days 18-22 of gestation (53.2 +/- 9.0 nmol/g on day 22, P > 0.05), but markedly increased during term labour (139 +/- 28.6 nmol/g, P < 0.05). Treatment with the antiprogestin onapristone suppressed uterine NO production and increased cervical production while continuous administration of progesterone from day 19 had the opposite effect. LPS produced a significant increase in cervical NO production in both the pregnant (8-fold) and non-pregnant (4-fold) states. All three known NOS isoforms (i.e., iNOS, nNOS and eNOS) were detected in the cervical samples but only two were present in the uterus (iNOs and eNOS). An increase in the presence of iNOS occurred during labour at term compared with cervices collected from day 19. This was contrary to the measurements of the isoform in the uterus. Also, there was a similar increase of nNOS in the cervix during labour. This isoform seemed absent in the uterus during gestation. No significant changes occurred in the abundance of eNOS in the cervix during labour at term compared with day 19. During preterm labour after onapristone, iNOS concentrations increased significantly in the cervix. In order to examine whether the NO pathway plays a role in cervical ripening, the effects of the nitric oxide synthesis inhibitor L-nitro-arginine methylester (L-NAME) on the duration of delivery and on cervical extensibility were also investigated. The duration of delivery was significantly prolonged in L-NAME-treated rats compared with the control group (2.4-fold). Moreover, cervical extensibility decreased significantly (1.7-fold) after in-vitro incubation with L-NAME (P < 0.005). We conclude that the NO system may have an active role in the cascade of processes involved in preparing the uterus and cervix for parturition.

In vivo NMR spectroscopic studies on the bioenergetic changes induced by metabolic modulators in Ehrlich ascites tumour cells

Changes in the energy metabolism of Ehrlich ascites tumour (EAT) cells induced by treatment with 2-deoxy-D-glucose (2-DG) alone and in combination with other metabolic modulators, were studied using in vivo nuclear magnetic resonance (NMR) spectroscopy. Accumulation of 2-DG-6-phosphate (2-DG-6-P) and cellular energy status as reflected in the ratio of beta ATP to inorganic phosphate (beta-ATP/Pi) in cells could be monitored as a function of time using P-31 NMR spectroscopy. Presence of 2-DG induced a significant decrease in the levels of nucleotide triphosphates, which continued to reduce for some time even after removing 2-DG from the vicinity of cells. When administered along with 3-O-methyl-D-glucose (3-O-MG), 2-DG phosphorylated at a slower rate and the resultant 2-DG-6-P accumulated to a lesser extent than that obtained with 2-DG alone. Treatment with Photosan II, a haematoporphyrin derivative (Hpd), has been reported to increase the glucose utilisation and rate of glycolysis. Upon concomitant administration of 2-DG along with Hpd (after Hpd pretreatment for 1-2 hr), the extent of phosphorylation of 2-DG increased. The combination of 2-DG with 3-O-MG or Hpd reduced the energy status (beta-ATP/Pi) to a greater extent and the recovery was considerably less upon removal of the treatment, compared to the effects of either drug administered separately. Since metabolic depletion of ATP is known to inhibit the post-irradiation DNA repair processes, it is hypothesized that the use of these drug combinations, as adjuvants to tumour radiotherapy, should enhance the therapeutic efficacy and selectivity.

Improving cancer radiotherapy with 2-deoxy-D-glucose: phase I/II clinical trials on human cerebral gliomas

PURPOSE

Evaluation of tolerance, toxicity, and feasibility of combining large fraction (5 Gy) radiotherapy with 2-deoxy-D-glucose (2DG), an inhibitor of glucose transport and glycolysis, which has been shown to differentially inhibit repair of radiation damage in cancer cells.

METHODS AND MATERIALS

Twenty patients with supratentorial glioma (Grade 3/4), following surgery were treated with four weekly fractions of oral 2DG (200 mg/kg body weight) followed by whole brain irradiation (5 Gy). Two weeks later, supplement focal radiation to the tumor (14 Gy/7 fractions) was given. Routine clinical evaluation, x-ray computerized tomography (CT), and magnetic resonance (MR) imaging were carried out to study the acute and late radiation effects.

RESULTS

All the 20 patients completed the treatment without any interruption. The vital parameters were within normal limits during the treatment. None reported headache during the treatment. Mild to moderate nausea and vomiting were observed during the days of combined therapy (2DG + RT) in 10 patients. No significant deterioration of the neurological status was observed during the treatment period. Seven patients were alive at 63, 43, 36, 28, 27, 19, and 18 months of follow-up. In these patients, the clinical and MR imaging studies did not reveal any late radiation effects.

CONCLUSIONS

Feasibility of administering the treatment (2DG + 5 Gy) is demonstrated by the excellent tolerance observed in all 20 patients. Further, the clinical and MR studies also show the absence of any brain parenchymal damage.

The stability of estrogen and progesterone receptors in patients receiving preoperative chemotherapy for locally advanced breast carcinoma

The determination of estrogen (ER) and progesterone receptor (PR) content is routine in the management of carcinoma of the breast. Such data are commonly used to predict responses to endocrine therapy. Preoperative chemotherapy is often utilized in the treatment of patients with locally advanced carcinoma of the breast. However, little attention has been focused upon the effect of preoperative chemotherapy on hormonal receptor expression in that setting. The purpose of this study is to evaluate the effect of preoperative chemotherapy on ER and PR expression in patients with locally advanced breast carcinoma. Patients with T3 or T4 adenocarcinoma of the breast from Charity Hospital in New Orleans were studied. Levels of ER and PR were determined from tissue blocks obtained at diagnostic biopsy, as well as after the preoperative chemotherapy. The receptor levels were determined using immunohistochemistry and quantified using image analysis. We evaluated 21 locally advanced cancer patients who received at least three cycles of standard chemotherpay regimens. Of these patients, 11 achieved a partial response, with 3 achieving a complete response after preoperative chemotherapy. A total of 33 per cent of patients had a significant change in hormonal receptor content after preoperative chemotherapy. ER changed in 17%, PR in 22%, and both ER and PR in 6%. These data show that ER and/or PR expression changed in 33% of patients studied. Further, ER and PR status does not appear to predict or correlate with response to chemotherapy. This suggests that determination of ER and PR may best be performed from definitive resection specimens in patients who receive preoperative chemotherapy.

2-DG induced modulation of chromosomal DNA profile, cell survival, mutagenesis and gene conversion in X-irradiated yeast

Effects of post-irradiation modulation in presence of 2-deoxy-D-glucose and yeast extract, on chromosomal DNA profile, cell survival, reverse mutation (ILV+) and gene conversion (TRP+), were studied in X-irradiated stationary phase yeast cells (diploid strain D7 of Saccharomyces cerevisiae). The damage and repair in chromosomal DNA bands, resolved by using contour clamped homogeneous electric pulsed-field gel electrophoresis (PFGE) technique, was estimated by calculating intensity ratio, rho n (rho n I(n)/I(t); where I(n) is the intensity of nth band in a lane and I(t) is the sum of intensities of all bands and the well in the lane). The data indicate linear correlation between relative compactness (tau) of a chromosome [chromosome size (Kb)/length of synaptonemal complex (microns)] and DNA damage and repair. The chromosome repair kinetics were biphasic, showing initial decrease followed by an increase in rho n. Variations were observed among different chromosomes with respect to DNA damage, repair and post-irradiation repair modulation. 2-DG inhibited both components of chromosomal DNA repair and also repair of potentially lethal damage but enhanced frequencies of mutants. Relatively the effects on revertants were greater in cells irradiated with lower doses (50 Gy) of X-rays and post-irradiation incubation in presence of phosphate buffer having 2-DG (50 mM) and glucose (10 mM). Yeast extract increased frequencies of revertants and convertants thus promoting error-prone DNA repair. Yeast extract in combination with 2-DG showed complex effects on chromosomal DNA repair and enhanced mutagenesis further.

Tamoxifen regulation of ectocervical cell differentiation

OBJECTIVE

To determine the effects of tamoxifen on the growth and differentiation of normal human cervical cells and compare those effects with those of a synthetic estrogen, diethylstilbestrol (DES). In addition, the effects of these compounds on immortalized cervical cells and cervical tumor cells were ascertained.

METHODS

Growth curves were used to determine the effects on cell proliferation. The expression of several proteins was used to determine the effects on cell differentiation. Binding assays and Western analysis were used to determine estrogen receptor levels.

RESULTS

Both tamoxifen and DES inhibited the proliferation of normal cervical cells. This growth inhibition was coincident with an increase in cell differentiation as determined by cornified envelope formation. The increase in envelope number was not accompanied by an increase in involucrin or cornifin, two protein precursors of the envelope. The activity of transglutaminase, which enzymatically incorporates precursor proteins into the envelope, was not stimulated following treatment. Diethylstilbestrol did not alter the growth or differentiation of the human papillomavirus 16-immortalized cell line ECE16-1 or any of the cervical tumor cell lines. Of all the immortalized or cancer cell lines, only Caski cells were growth inhibited by tamoxifen. Normal ectocervical epithelial cells and Caski cells expressed the high-affinity 56-kDa estrogen receptor, but 3H-estradiol binding was not detected in cell extracts from either ME180 or ECE16-1 cells. Nevertheless, extracts from ME180 cells contained an immunoreactive band at the appropriate molecular weight for the estrogen receptor.

CONCLUSIONS

These results suggest that tamoxifen and DES act similarly in normal cervical cells to promote cervical cell differentiation. However, because Caski cell growth was inhibited by tamoxifen and not DES, the effects of tamoxifen in these cells may be mediated by non-estrogen receptor mechanisms.

Safety of intrauterine administration of purified neem seed oil (Praneem Vilci) in women & effect of its co-administration with the heterospecies dimer birth control vaccine on antibody response to human chorionic gonadotropin

Praneem Vilci (PV), purified neem oil was reported to exercise a reversible antifertility effect after a single intrauterine instillation in rodents and primates without any adverse effects. After toxicology, drug regulatory and ethical clearances, a phase I clinical trial was conducted on PV. Eighteen healthy tubectomised women were enrolled to evaluate the safety of a single intrauterine instillation of PV and to determine the effect of its co-administration on anti-hCG response to the heterospecies dimer (HSD) hCG vaccine. Eight women received PV alone and ten women were given the HSD-hCG vaccine in addition. Base-line and post-treatment haematological and biochemical profiles were determined as also the mid-luteal serum progesterone. Endometrial biopsies were examined to assess ovulatory status and the effect of intrauterine treatment with PV on the endometrium. Anti-hCG antibody titres were estimated in women who were concurrently immunized with the HSD vaccine. No untoward reaction was observed in any woman. Menstrual pattern and ovulatory status remained unaltered. Endometrial biopsy after PV instillation in one woman showed non-specific endometritis but she remained asymptomatic. Mild eosinophilia was seen in two women and this reverted to normal on its own. All women receiving PV and the HSD vaccine generated antibodies against hCG. Our data show that intrauterine administration of PV is safe and does not prevent the antibody response to HSD-hCG vaccine.

A simple in vitro method to detect singlet oxygen and to compare photodynamic activity using alkaline phosphatase

A simple, sensitive and reliable in vitro method based on photodynamic inactivation of alkaline phosphatase to detect singlet oxygen and for evaluating relative photosensitizing efficiencies of photosensitizers such as hematoporphyrin (Hp) and phthalocyanines has been developed and compared with photobleaching of p-nitroso dimethyl aniline (RNO) and photooxidation of L-tryptophan. Inactivation of alkaline phosphatase is dependent both on light fluence and sensitizer concentration. Scavengers like mannitol and azide anion indicated the involvement of singlet oxygen in the deactivation of alkaline phosphatase, since azide anion provided concentration dependent protection whereas mannitol had no effect and that compared to ordinary water, photoinactivation of alkaline phosphatase was three times higher in 65% D2O. Alkaline phosphatase appears to be resistant to free radical attack (particularly to OH radicals) since hydrogen peroxide alone or in presence of ferrous ions did not reduce the enzyme activity and mannitol or azide anion gave no significant protection when alkaline phosphatase was irradiated with Co-60 gamma rays up to 2 K Gy. With the present method using red light, the chloroaluminium phthalocyanine sulphonates prepared by sulphonation showed higher and the corresponding condensation product lower photodynamic activity; Hp being intermediate and Mn- and Gd-phthalocyanines had no photodynamic activity.

Modulation of repair and fixation of UV-induced damage and its effects on mutagenesis in yeast

Modulation of repair of UVC-induced damage under different post-irradiation nutritional conditions and its effects on mutagenesis were studied in stationary phase cells of diploid strain D7 of Saccharomyces cerevisiae. Reverse mutation and gene conversion frequencies at ILV and TRP locus were measured in the respective omission media. It was observed that post-irradiation (150 x 10(-3) J/m2) repair in presence of (i) 2-deoxy-D-glucose (2-DG, 10 mM) resulted in decreased surviving fraction (56 +/- 5%) and increase in frequencies of revertants and gene convertants (122 +/- 10% & 132 +/- 14% respectively), (ii) yeast extract enhanced the frequency of revertants to a large extent (204 +/- 18%) and (iii) yeast extract and 2-DG together further increased the frequencies of revertants (304 +/- 15%) and gene convertants (151 +/- 12%); when compared with irradiated controls in phosphate buffer glucose; the observed changes being statistically significant (P < 0.05, Student's t test). These results indicate that (i) 2DG reduces the error-free DNA repair in yeast, (ii) yeast extract increases error-prone DNA repair and thus, in combination with 2-DG, further promotes mutagenesis.

Heterogeneity in DNA content & proliferative status of human brain tumours

Intra-tumour and inter-tumour heterogeneity in the cytokinetic organization was studied in 235 primary human brain tumours. DNA index (DI; relative tumour cell DNA content) and proliferating fraction (%PF; a measure of proliferative status) were analyzed in tumour biopsy by flow cytometry using a DNA specific fluorochrome (DAPI) and internal standards (chicken erythrocytes, CE). Incidence of micronuclei was studied in tumour biopsy tissue as well as in explants maintained in organ culture. Clonal diversity (implied by the presence of multiple peaks in the DNA histograms) was highest among medulloblastomas (44%) followed by gliomas (19%) and meningiomas (14%). Nearly 85 per cent of the malignant gliomas analyzed (histological grade III/IV) exhibited a great deal of regional variation in the proliferative status as well as micronuclei frequency as compared to meningiomas. Inter-tumoural variations in the DNA content was highest among gliomas (0.9 < DI < 3.6) and lowest among schwannomas (1.7 < DI < 2.2). Similarly, the distribution of %PF values was also broader (10-49%) in gliomas as compared to the other primary brain tumours (5-36%). Analysis of tumours taking both DI and %PF values improved the ability to discern histologically graded low and high tumours. Analysis of clonal diversity and spatial heterogeneity in the cytokinetic parameters could complement the clinicopathological findings in assessing the biological behaviour of human brain tumours, facilitating the prognostification and design of otpimal treatment regimen.

Effects of 2-deoxy-D-glucose on the photosensitisation-induced bioenergetic changes in Saccharomyces cerevisiae as observed by in vivo NMR spectroscopy

Haematoporphyrin (HP), a photosensitiser used for photodynamic therapy (PDT) of tumours, has been observed to affect the cellular energy metabolism both in the absence and presence of light. The effects of HP alone and in combination with 2-deoxy-D-glucose (2-DG) on photosensitisation-induced bioenergetic changes in yeast (Saccharomyces cerevisiae) were monitored and compared using in vivo NMR spectroscopy. Presence of HP was seen to reduce polyphosphates and inorganic phosphate in the dark. Upon photo-irradiation, polyphosphates and sugar phosphates decrease drastically with concomitant rise in inorganic phosphates. Presence of 2-DG in the medium also induced a decrease in polyphosphates and nucleotide triphosphates and the build-up of 2-deoxy-D-glucose-6-phosphate (2-DG-6-P) was clearly detectable. The combination of 2-DG and HP followed by photo-irradiation, however, induced a significant reduction in intracellular pH and beta phosphate of ATP/inorganic phosphate (beta-ATP/Pi) ratio decreased to a larger extent as compared to similar treatment without 2-DG. These observations confirm that polyphosphates are utilised as phosphogen, as phosphate store to be used during phosphate deprivation and as alternative energy source under conditions of energy deficiency induced by HP-PDT and/or 2-DG. The present results further suggest that photodynamic therapy could be made more effective in conjunction with 2-DG administration.

Mode of delivery in deep transverse arrest

OBJECTIVES

To determine the trends in the mode of delivery in deep transverse arrest (DTA) over two decades and their impact on maternal morbidity and neonatal outcome.

METHODS

Obstetric and neonatal records of women with DTA who delivered at Nehru Hospital, PGIMER, Chandigarh in the years 1970, 1980 and 1990 were analyzed.

RESULTS

Although Kielland's forceps was used very frequently in 1970 (44.4%) it had disappeared by 1990 because of increased morbidity associated with it. Instead, use of vacuum extractor and cesarean section has increased over the years. Manual rotation forceps extraction was the most commonly used vaginal method of delivery over two decades (49.5%). Perinatal outcome was better with manual rotation forceps extraction or vacuum extraction as compared to Kielland's forceps. Cesarean section was associated with a high incidence of birth asphyxia (30%).

CONCLUSIONS

Manual rotation forceps extraction and vacuum extraction are safe methods of delivery in DTA. Cesarean section as an alternative does not improve the perinatal outcome.

Modification of radiation damage in transformed mammalian cells by 5-bromo-2-deoxy-uridine and 2-deoxy-D-glucose

The effects of 2-deoxy-D-glucose (2-DG) and 5-bromo-2-deoxy-uridine (BrdU) on gamma ray (60Co) induced damage were studied in monolayer cultures of transformed mammalian (BHK-21) cells. Micronuclei formation and changes in DNA content dispersion were used as indices of cytogenetic damage. Exposure of cells to BrdU (0.8 microM) for nearly two cell cycles before irradiation significantly increased micronuclei formation in exponentially growing cells. Incubation of irradiated cells under suboptimal growth conditions (in HBSS) for 4 hr, instead of growth medium, decreased the manifestation of damage. However, post-irradiation presence of 2-DG (5 mM, equimolar with glucose; 4 hr) in growth medium or HBSS significantly increased radiation damage. The effects of 2-DG treatment following irradiation in plateau phase were quantitatively less. These results suggest that: (i) radiation induced DNA lesions leading to micronuclei formation in BrdU incorporated cells are partly repairable; (ii) 2-DG could increase radiation induced cytogenetic damage in transformed mammalian cells, possibly by inhibiting the cellular repair processes; and (iii) combination of 2-DG treatment may decrease the BrdU doses required for radiosensitization of proliferating tumour cell populations.

Phase I and II study of high-dose ifosfamide, carboplatin, and etoposide with autologous bone marrow rescue in lymphomas and solid tumors

PURPOSE

High-dose chemotherapy produces durable disease-free remissions in a minority of patients with resistant lymphomas and solid tumors. In an attempt to improve on the available regimens, ifosfamide, carboplatin, and etoposide (ICE) were selected for a new high-dose regimen because of their favorable spectrum of nonhematopoietic toxicity and evidence of synergy in in vitro systems.

PATIENTS AND METHODS

Forty-one patients with drug-resistant Hodgkin's and non-Hodgkin's lymphomas, and breast and testicular cancers were entered onto a phase I and II trial of a single course of ICE with autologous bone marrow rescue. Before transplantation, all patients received combination chemotherapy until maximal tumor response was achieved.

RESULTS

Patients received total doses of ifosfamide from 10 to 18 g/m2, carboplatin from 0.9 to 1.98 g/m2, and etoposide from 0.6 to 1.5 g/m2 administered during a 4-day period, with a maximum-tolerated dose (MTD) of ifosfamide 16 g/m2, carboplatin 1.8 g/m2, and etoposide 1.5 g/m2. The dose-limiting toxicities included irreversible renal, cardiac, and CNS dysfunction. There were three toxic deaths (7%), and all occurred above the MTD. Thirteen patients who were treated at the MTD tolerated the regimen well; reversible renal dysfunction and grade 2 mucositis commonly were observed. Of 23 heavily pretreated patients with persistent disease at the time of transplant, 10 (43%) achieved complete remissions (CRs) and 11 (48%) achieved partial remissions (PRs). Hodgkin's and non-Hodgkin's lymphoma patients who were treated at or below the MTD had a median potential follow-up of 11.9 months, and 12-month progression-free survivals of 62% and 48%, respectively.

CONCLUSION

High-dose ICE with bone marrow rescue was well tolerated with a high response rate, and should be considered for further testing.

Epstein-Barr virus and Burkitt's lymphoma

Recent investigations indicate that Burkitt's lymphoma consists of several subtypes, defined by their clinical and molecular features. Each geographical region so far studied appears to consist of a different mixture of subtypes. Interestingly, there appear to be geographic 'gradients' with respect to the fraction of tumors associated with EBV and the type of 8;14 chromosomal translocation. The rate of EBV association is highest in Equatorial Africa, lowest in North America and intermediate in South America. The fraction of tumors with breakpoints far upstream of the c-myc gene follows a similar pattern. These findings strongly suggest that the subtypes of Burkitt's lymphoma are environmentally determined, and we propose that the pattern of infection (e.g. malaria) to which the young child is exposed influences the tumor subtype distribution by altering the relative and absolute numbers of various B cell precursors at sites of B cell ontogeny (the bone marrow, and possibly mesentery). These B cell precursors are the cells which are susceptible to the specific chromosomal translocations associated with Burkitt's lymphoma. We further propose that immunoglobulin enhancers (recognized and unrecognized) both influence the likelihood of the translocation occurring, and in at least a fraction of cases, contribute to the deregulation of a c-myc. EBV, via EBNA-1, the only invariably expressed latent-gene in Burkitt's lymphoma, probably influences c-myc expression in Burkitt's lymphoma by increasing immunoglobulin enhancer function. Thus, in effect, EBV collaborates with the translocations associated with Burkitt's lymphoma in causing c-myc deregulation. This collaboration is independent of the breakpoint location. While other molecular abnormalities must be able to contribute to myc deregulation in the same way, EBV association in Burkitt's lymphoma is probably determined by the age at which EBV infection occurs (being more likely when infection occurs in very young children) and perhaps also by other infectious diseases that numerically influence the fraction, and predominant stage of differentiation (and hence translocation breakpoint sites) of immature B cells infected by EBV. The presence of EBV in many such cells greatly increases the incidence rate of Burkitt's lymphoma, since one of the genetic lesions needed to deregulate c-myc is already present.