Four new triterpenes from the heartwood of melaleuca leucadendron

Four new triterpenes, eupha-7,24-diene-3beta,22beta-diol (1), 20-taraxastene-3alpha,28-diol (2), 3alpha,27-dihydroxy-28, 20beta-taraxastanolide (3), and 3alpha-hydroxy-13(18)-oleanene-27, 28-dioic acid (4) have been isolated from the heartwood of Melaleuca leucadendron. The structures and stereochemistry of 1-4 have been determined by spectroscopic analysis, with compounds 3 and 4 being investigated in the forms of their diacetate (3a) and dimethyl (4a) derivative, respectively.

Advanced stage and unfavorable Hodgkin's disease in the Chinese-a 20-year experience

We retrospectively analyzed 57 patients with advanced stage (stage III/IV) or unfavorable (presence of B symptoms or bulky disease) Hodgkin's disease from January 1977 to December 1997. There were 29 male and 28 female patients. The median age was 27 years old (range, 13-59). Lactate dehydrogenase levels ranged from 104 units/l to 2320 units/l (median, 433). Eighteen (31.6%), 13 (22.8%), and 26 (45.6%) patients had stage II bulky, stage III, and stage IV disease, respectively. Twenty-five (44%) patients had B symptoms. One (1.8%), 3 (5.3%), 36 (63.2%), and 17 (29.8%) had lymphocyte predominant, lymphocyte depleted, nodular sclerosis, and mixed cellularity histology, respectively. Chemotherapy regimens included mechlorethamine, vincristine, procarbazine, prednisone (MOPP) (n = 9), adriamycin, bleomycin, vinblastine, dacarbazine (ABVD) (n = 23), MOPP alternating with ABVD (n = 13), and COPP-ABV hybrid (n = 12). Complete remission was achieved in 47 (82.4%) patients. Eleven patients (23%) relapsed after the first complete remission and four (36%) attained a second complete remission with salvage chemotherapy. Projected overall survival was 69.0% at 10 years and 20 years. Disease-free survival rates were 71% at 10 years and 20 years. Of the potential prognostic factors analyzed (age, sex, stage, lactate dehydrogenase, serum albumin level, regimen, B symptoms and bulky disease) by using the Cox regression model, only a low albumin level was found to adversely affect overall survival (P = 0.003). In conclusion, despite the relative low incidence of Hodgkin's disease in Hong Kong Chinese, the treatment outcomes in patients with advanced stage or unfavorable Hodgkin's disease is comparable to Caucasian patients.

Production of D-p-hydroxyphenylglycine by N-carbamoyl-D-amino acid amidohydrolase-overproducing Escherichia coli strains

The N-carbamoyl-D-amino acid amidohydrolase (D-carbamoylase) gene from Agrobacterium radiobacter NRRL B11291 has been successfully cloned and expressed in Escherichia coli. Subcloning of the D-carbamoylase gene into different types of vectors and backgrounds of E. coli strains showed that the optimal expression level of D-carbamoylase was achieved in a ColE1-derived plasmid with a 150-fold increase in specific enzyme activity compared to that in a pSC101-derived plasmid. In addition, the recombinant plasmids were very stable in the E. coli strain ATCC11303 but not in JCL1258 tested here. Employing the recombinant E. coli strain DH5alpha/pAH61 for D-p-hydroxyphenylglycine production showed that the cell was capable of transforming N-carbamoyl-D-hydroxylphenylglycine to D-p-hydroxyphenylglycine with a molar conversion yield of 100% and a production rate of 1.9 g/(L h). In comparison with A. radiobacter NRRL B11291, this productivity approximates a 55-fold increase in D-hydroxyphenylglycine production. This result suggests the potential application of recombinant E. coli strains for the transformation reaction.

A novel four-drug ablative regimen with hemopoietic stem cell rescue for patients with breast cancer: a phase II study

High-dose chemotherapy and autologous hemopoietic stem cell transplantation (HSCT) may provide durable progression-free survival in some patients with stage IV breast cancer (S4Brca). We have studied a new four-drug intensive preparative regimen with HSCT in a group of 158 women with S4Brca to define the risk and potential benefit of this regimen in this patient population. From May 1988 through May 1997, 158 women with S4Brca at a single center were treated with cisplatin, etoposide, thiotepa, and cyclophosphamide (PETCy) plus autologous HSCT Eligible patients were also treated with posttransplant involved-field radiation therapy. Patients with estrogen-receptor positive tumors not previously treated with tamoxifen also received this therapy for 5 years following transplantation. All patients experienced significant toxicity requiring blood-product support and parenteral nutrition. Eighteen patients (11%) died of regimen-related toxic events. With a median follow-up of 540 days for surviving patients, a retrospective Kaplan-Meier analysis projects an overall survival of 38+/-8.5% (95% CI) at 890 days with a maximum follow-up of 8.8 years. For 52 patients in sensitive relapse, the median event-free survival time is 767 days, with 46.2+/-15.3% (95% CI) predicted to be alive at 884 days with a maximal follow-up of almost 9 years. Nearly one-half of patients in this study with S4Brca in sensitive relapse have experienced durable remissions following PETCy ablation and HSCT. Although toxicity is significant, the PETCy regimen produces a favorable balance between efficacy (event-free survival) and treatment failure (relapse + regimen-related toxic death) compared with published results. These data suggest that within the high-dose range for preparative therapy, a steep dose-response may exist for breast cancer. Trials comparing the dose intensity of preparative regimens are warranted.

Outcome of Chinese patients with chronic myeloid leukaemia (CML) underwent allogeneic bone-marrow transplantation (BMT)

Clinical studies have shown that patients with chronic myeloid leukaemia (CML) treated with allogeneic bone-marrow transplantation (BMT) experience not only prolonged disease-free survival but also complete cure in some. Therefore, we followed a cohort of 81 Chinese patients who received allogeneic BMT.

PATIENTS AND METHODS

The donors were either relatives (65 siblings, 1 parent) or unrelated volunteers (15). BMT was performed at a median interval of 11.6 months from diagnosis of CML, and the stages of disease before BMT were: first chronic phase (60 patients), accelerated or second chronic phase in (10 patients), and blastic crisis (11 patients). Three conditioning regimens were employed: Bu-Cy, Cy-TBI, or Bu-Cy-TBI. Standard cyclosporin and short methotrexate protocol were used for acute graft-versus-host disease (GvHD) prophylaxis.

RESULTS

There were five graft failures with three after related BMT. Patients after related or unrelated BMT had a comparable rate of neutrophil recovery (median = 22 days), but significant delay in platelet recovery occurred after unrelated BMT (median = 34 vs. 20 days, P < 0.05). The latter also had higher incidence of acute GvHD (73% vs. 41%, P < 0.05), although the incidence of chronic GvHD was not different between groups. At a median follow-up of 43.5 months, patients after related BMT had a significantly better rate of disease-free survival (68% vs. 37.3%, P < 0.05) and overall survival (81% vs. 38.9%, P < 0.05) at 4 years. Subgroup analysis of patients after related BMT showed the outcome was better when they were transplanted at first chronic phase. Multivariate analysis showed that advanced disease (RR = 2.01, 95% CI = 1.48-2.73) significantly worsened the outcome of BMT, whereas the presence of chronic GvHD had a protective effect against relapse and survival (RR = 0.09, 95% CI = 0.02-0.38).

CONCLUSION

Allogeneic BMT is a curative form of treatment for patients with CML. Treatment outcome is best for those who undergo transplants from HLA-matched siblings during the first chronic phase.

Use of Embryonic and Somatic Cells for Production of Transgenic Domestic Animals

In contrast to the highly developed genetic modification systems available for manipulating the mouse genome, at this time only simple gain of function modifications can be undertaken in domestic species. Clearly, the greatest barrier to gene targeting in domestic species has been the unavailability of cell lines that can be modified in vitro and still be used to generate a living organism. In the mouse, the embryonic stem (ES) cells and embryonic germ (EG) cells have fulfilled that role. While the nuclear transfer procedures have solved this problem in sheep and cattle, in swine ES and EG cells are still needed. In addition, targeting in domestic species is affected by the need to develop targeting constructs containing isogenic DNA regions. As a result, it is necessary to isolate the gene of interest, sequence required regions, and develop isogenic targeting constructs by technologies such as long-range PCR. On the positive side, enrichment protocols developed in the mouse can be applied to domestic species, thus facilitating the identification of correctly modified cell lines. Hence, progress in mammalian cloning, the development of EG cell lines, and advances in gene targeting presently allows the introduction of precise genetic modifications into the domestic animal genome.

[A preliminary report on two distinct tumor-suppressor regions on chromosome 1p36.2-p36.3 in human hepatocellular carcinomas]

OBJECTIVE

Both cytogenetic and molecular genetic analyses have unveiled non-random genomic alterations in the distal short arm of human chromosome 1 associated with a number of human malignancies including heptatocellular carcinoma (HCC). The aim of this investigation is to determine the precise region of deletion that may harbor the putative tumor suppressor genes in HCC.

METHODS

For the study of the loss of heterozygosity (LOH), 38 cases of hepatitis B virus (HBV) associated HCC and their corresponding non-tumor liver tissues were detected with 43 microsatellite polymorphic markers particularly focusing on 1p.

RESULTS

Twenty-eight of the 38 (74%) tumors showed LOH on at least one locus on 1p36.2-p36.3. Two distinct smallest common deleted regions (SCDRs) with different patterns of deletion were identified. The first SCDR is located on locus D1S2795 at 1p36.3, between loci D1S2145 and D1S2893. The second SCDR is located at 1p36.2, between loci D1S244 and D1S489. Both of the SCDRs have not been previously described in HCC. In addition, a region of possible homozygous deletion (HD) was also detected within the second SCDR between loci D1S1597 and D1S489 by comparative multiplex PCR. This is the first observation of a possible homozygous deletion on the distal short arm of chromosome 1 in HCC as well as in human tumors.

CONCLUSIONS

The high-resolution deletion mapping of 1p36.2-p36.3 in HCC in this study confirmed the presence of two distinct regions of deletion. Our data strongly suggest the presence of at least two tumor suppressor regions on 1p36.2-p36.3 and play an important role in the pathogenesis of HBV associated HCC. These results also provide a basis for further studies directed at cloning potential tumor suppressor genes in these regions.

Donor lymphocyte infusion induced molecular remission in relapse of acute myeloid leukaemia after allogeneic bone marrow transplantation

Donor lymphocyte infusion (DLI) has been used successfully to induce remissions in relapse of acute myeloid leukaemia (AML) after bone marrow transplantation (BMT), but molecular eradication of leukaemia has rarely been documented. A patient with AML-M4Eo relapsed after HLA-identical sibling BMT in first complete remission (CR). Cytogenetic and molecular genetic investigations confirmed inv(16) and CBFbeta/MYH11 fusion characteristic of M4Eo. A second remission was obtained with chemotherapy. Full donor chimerism was demonstrated by fluorescence in situ hybridisation. However, molecular evidence of minimal residual disease still persisted, and donor lymphocyte infusion (DLI) was administered. This resulted in molecular eradication, and the patient remained in clinical and molecular remission 16 months from DLI. Our observations showed that, for AML relapse after BMT, molecular leukaemia eradication could be achieved by DLI so that, in cases where genetic markers are available, molecular monitoring should be performed to assess the efficacy of treatment.

Prophylactic reinfusion of T cells for T cell-depleted allogeneic bone marrow transplantation

To increase the graft-vs.-leukemia (GVL) effect while maintaining a low mortality from graft-vs.-host disease (GVHD), we conducted a prospective study of T cell titration for 144 patients (90 related, 54 unrelated) between June 1994 and June 1997. Following infusion of a T cell-depleted marrow graft, predetermined doses of T cells, based on the risk factors for GVHD, were administered up to 3 times if greater than a grade II acute GVHD was not seen. Graft failure occurred in three unrelated recipients (2%). Cumulative grades II-IV acute GVHD were seen in 58 +/- 9% of all recipients; 52 +/- 11% related and 75 +/- 13% unrelated. The incidence of grades II-IV acute GVHD following the third add-back (AB) of T cells 78 median days after marrow infusion was lower than that of the earlier ABs: first AB, 36 +/- 8%; second AB, 32 +/- 11%; third AB, 15 +/- 12% (p < 0.05). Chronic GVHD occurred in 56 +/- 12% of related and 79 +/- 16% of unrelated patients. Six died of acute GVHD and two died of chronic GVHD, with an overall GVHD mortality of 6 +/- 4%. In multivariate analyses, unrelated recipients and patients at low risk for GVHD who received a larger number of T cells were identified as patient groups with significant risk for acute and chronic GVHD (both p < 0.05). Unrelated transplant is also shown to be significant for GVHD-related death (p < 0.01). Relapse-free survival of patients with leukemia was shown to be most dependent on chronic GVHD and grades II-IV acute GVHD (both p < 0.01). Anti-leukemic activity independent of GVHD was not observed.

Prevention of ultraviolet radiation-induced suppression of contact hypersensitivity by Aloe vera gel components

We have recently reported that Aloe vera gel contains small molecular weight immunomodulators, G1C2F1, that restore ultraviolet B (UVB)-suppressed accessory cell function of epidermal Langerhans cells (LC) in vitro. In the present study we evaluated the UVB-protective activity of G1C2F1 in vivo. Exposure of the shaved abdominal skin of mice to 2.4 KJ/m2 of UVB radiation resulted in suppression of contact sensitization through the skin to 41.1%, compared to normal unirradiated skin. Topical application of G1C2F1 immediately after irradiation reduced this suppression significantly. The percentage recovery of UVB-suppressed contact hypersensitivity (CHS) response was 52.3, 77.3, and 86.6% when the irradiated skin was treated once with 0.1, 0.5, and 2.5 mg/ml of G1C2F1-containing cream, respectively. G1C2F1 did not show nonspecific stimulatory activity on CHS response. The present study, together with the previous observation, show that Aloe vera gel contains small molecular weight immunomodulators that prevent UVB-induced immune suppression in the skin by restoration of UVB-induced damages on epidermal LC.

Outcome of epithelial ovarian cancer in women under 40 years of age treated with platinum-based chemotherapy

We retrospectively investigated the outcome of ovarian cancer in women aged less than 40 years treated in three randomised phase III studies of platinum-based chemotherapy. 624 patients had invasive epithelial ovarian cancer. A Cox proportional hazard model was used to study prognostic variables. 29 women (5%) were under 40 years of age. Stage, histological grade and amount of residual disease were significantly worse in women aged > or = 40 years. Median follow-up was 66.7 months. At 5 years 65% of women below 40 years of age were alive compared with 20% of older women (95% confidence interval (CI) of the difference 27.1-63.0). The progression-free interval was 59% versus 16% (95% CI 24.3-60.8). No patient under 40 years of age relapsed after 18 months. Age > or = 40 years was a poor prognostic variable, particularly for serous tumours, the commonest subtype in younger women (hazard ratio (HR): 3.33). Other prognostic factors were Eastern Cooperative Oncology Group (ECOG) performance status (HR: 1.25), presence of residual disease (HR: 1.43), histological grade (HR: 1.36) and International Federation of Gynaecology and Obstetrics (FIGO) stage (HR: 1.47). These results suggest that there are biological differences in the behaviour of serous carcinoma of the ovary in women of reproductive age compared with older women.

Identification and in vivo functional analysis of a virginiamycin S resistance gene (varS) from Streptomyces virginiae

BarA of Streptomyces virginiae is a specific receptor protein for virginiae butanolide (VB), one of the gamma-butyrolactone autoregulators of the Streptomyces species, and acts as a transcriptional regulator controlling both virginiamycin production and VB biosynthesis. The downstream gene barB, the transcription of which is under the tight control of the VB-BarA system, was found to be transcribed as a polycistronic mRNA with its downstream region, and DNA sequencing revealed a 1,554-bp open reading frame (ORF) beginning at 161 bp downstream of the barB termination codon. The ORF product showed high homology (68 to 73%) to drug efflux proteins having 14 transmembrane segments and was named varS (for S. virginiae antibiotic resistance). Heterologous expression of varS with S. lividans as a host resulted in virginiamycin S-specific resistance, suggesting that varS encoded a virginiamycin S-specific transport protein. Northern blot analysis indicated that the bicistronic transcript of barB-varS appeared 1 to 2 h before the onset of virginiamycin M1 and S production, at which time VB was produced, while exogenously added virginiamycin S apparently induced the monocistronic varS transcript.

Materials and design concepts for an intervertebral disc spacer. I. fiber-reinforced composite design

The intervertebral disc is a complex joint anatomically and functionally. It may be displaced or damaged due to trauma or a disease process. To alleviate this condition, it may be necessary to remove the involved disc surgically and fuse the two adjacent vertebrae. Fusion is one option; however, replacing the damaged disc (or part thereof) with a suitable synthetic equivalent to allow near normal joint motion is more desirable. Unfortunately, the complex mechanical properties of the lumbar disc cannot be duplicated with homogeneous synthetic materials (polymers). To overcome this fundamental problem we have developed rational designs utilizing biocompatible thermoplastic elastomers of various stiffnesses (durometers) with and without fiber reinforcements. Our design consisted of three components analogous to the natural end plates, annulus, and nucleus. In this study only the fiber-reinforced design is considered. The variables examined in the present study included orientation of the fiber layers, number of fiber layers, and order of the reinforcing layers. The results of mechanical testing of the fiber reinforced disc spacer indicate that the range of compressive and torsional properties can be achieved. The results further demonstrate that properly developed, this design results in properties similar to the natural disc. Designs developed provided adequate compression and compression torsion properties for a synthetic spine disc spacer.

Synthesis and antiviral activity of D- and L-isodideoxy nucleosides with exocyclic-methylene

Novel D- and L-isodideoxynucleosides were synthesized starting from D- and L-xylose and evaluated for antiviral activities against HIV-1, HSV-1, HSV-2, HBV and HCMV, respectively.

Fatal disseminated Trichoderma longibrachiatum infection in an adult bone marrow transplant patient: species identification and review of the literature

Trichoderma longibrachiatum was recovered from stool surveillance cultures and a perirectal ulcer biopsy specimen from a 29-year-old male who had received an allogeneic bone marrow transplant for acute lymphoblastic leukemia. The amphotericin B (2.0 microgram/ml) and itraconazole (1.0 microgram/ml) MICs for the organism were elevated. Therapy with these agents was unsuccessful, and the patient died on day 58 posttransplantation. At autopsy, histologic sections from the lungs, liver, brain, and intestinal wall showed infiltration by branching septate hyphae. Cultures were positive for Trichoderma longibrachiatum. While Trichoderma species have been recognized to be pathogenic in profoundly immunosuppressed hosts with increasing frequency, this is the first report of probable acquisition through the gastrointestinal tract. Salient features regarding the identification of molds in the Trichoderma longibrachiatum species aggregate are presented.

Immunization with recombinant Helicobacter pylori urease decreases colonization levels following experimental infection of rhesus monkeys

Rhesus monkeys, naturally colonized with H. pylori as indicated by culture and histology were immunized with either 40 mg recombinant H. pylori urease administered orally together with 25 microg Escherichia coli heat-labile enterotoxin (LT) or immunized with LT alone. An initial 6 doses were administered over an 8 week period. All five vaccinated monkeys had a greater than two-fold rise in urease-specific serum IgG and IgA level and urease-specific salivary IgA was induced in 3 of 5 vaccinated animals after 6 or 7 doses of vaccine. Vaccination had no measurable therapeutic effect on H. pylori colonization. H. pylori was eradicated from these monkeys with a course of antimicrobials plus omeprazole, a 7th vaccine dose was given (10 months after the 6th dose) and they were rechallenged with H. pylori. Necropsy was performed 23 weeks after rechallenge and H. pylori colonization was determined by histological examination of 12 individual gastric sites. A significant reduction in colonization (p < or = 0.0001; Friedman's analysis of variance) was found in the vaccinated animals. Histopathologic examination of necropsy tissues also revealed a trend towards reduced gastritis and epithelial alterations in the vaccinated group compared to animals receiving LT alone. This study provides the first evidence for effective vaccination of nonhuman primates against H. pylori, and preliminary evidence that a reduction in bacterial density attributable to immunization may lessen gastric inflammation.

Oral immunization with recombinant Helicobacter pylori urease confers long-lasting immunity against Helicobacter felis infection

Recombinant Helicobacter pylori urease (rUre) has been shown to confer protection against challenge with Helicobacter felis in mice. The purpose of the present study was to examine duration of the immune response and long-term protective efficacy of immunization with rUre. Swiss Webster mice were orally immunized four times at weekly intervals with 100 microg rUre plus 5 microg heat-labile enterotoxin of Escherichia coli (LT) adjuvant, or with LT only. At 4, 10, 20 or 40 weeks post immunization, 25 rUre-immunized mice and control mice were challenged with H. felis and sacrificed at 2 or 10 weeks post-challenge. H. felis infection was assessed by gastric urease assay and by histology. Anti-H. pylori urease specific antibody levels were measured in serum and saliva both pre- and post-challenge. Over the 40 week time period, the infection rates in rUre-immunized mice were significantly lower than those in controls (p < 0.05) as assessed by gastric urease activity. Protection ranged from 79 100% at 2 weeks post-challenge and 63-78% at 10 weeks post-challenge. Gastric bacterial density in rUre-immunized mice was significantly lower than that of controls (p < 0.03) as determined by histologic assessment. Anti-urease antibody levels remained elevated in the serum and mucosal compartments at 39 weeks following immunization. This study shows that immunization with rUre plus LT results in long-lasting protective immunity against challenge with H. felis.

Essential role of STAT3 for embryonic stem cell pluripotency

Propagation of mouse embryonic stem (ES) cells in vitro requires exogenous leukemia inhibitory factor (LIF) or related cytokines. Potential downstream effectors of the LIF signal in ES cells include kinases of the Src, Jak, and mitogen-activated protein families and the signal transducer and transcriptional activator STAT3. Activation of nuclear STAT3 and the ability of ES cells to grow as undifferentiated clones were monitored during LIF withdrawal. A correlation was found between levels of STAT3 activity and maintenance of an undifferentiated phenotype at clonal density. In contrast, variation in STAT3 activity did not affect cell proliferation. The requirement for STAT3 was analyzed by targeted mutagenesis in ES cell lines exhibiting different degrees of LIF dependency. An insertional mutation was devised that abrogated Stat3 gene expression but could be reversed by Cre recombination-mediated excision. ES cells heterozygous for the Stat3 mutation could be isolated only from E14 cells, the line least dependent on LIF for self-renewal. Targeted clones isolated from other ES cell lines were invariably trisomic for chromosome 11, which carries the Stat3 locus, and retained normal levels of activated STAT3. Cre-regulated reduction of Stat3 gene copy number in targeted, euploid E14 clones resulted in dose-dependent losses of STAT3 activity and the efficiency of self-renewal without commensurate changes in cell cycle progression. These results demonstrate an essential role for a critical amount of STAT3 in the maintenance of an undifferentiated ES cell phenotype.

Cloning thymic precursor cells: demonstration that individual pro-T1 cells have dual T-NK potential and individual pro-T2 cells have dual alphabeta-gammadelta T cell potential

Thymic progenitors have the capacity to generate alphabeta T cells, gammadelta T cells, and NK cells. To determine whether these three lineages derive from a single precursor cell or from different precursors, a procedure was developed for cloning precursor cells from mouse embryonic thymus. The progeny of each pro-T cell clone were then tested for the potential to generate alphabeta, gammadelta, and NK cells. Of these precursor clones, about half displayed dual potential, developing into either T cells or NK cells, demonstrating the existence of a common T/NK precursor cell in the thymus. The other half of the clones were restricted to T cell development. No precursor clones were restricted to NK development. The common T/NK precursors were shown to be of the pro-T1 (CD25(-)) stage whereas the T-restricted precursors were shown to be of the later pro-T2 (CD25(+)) stage. Both alphabeta and gammadelta T cells were generated from all clones derived from either pro-T1 or -T2 precursors. This shows that commitment of a cell to the alphabeta versus gammadelta lineages does not precede rearrangement of the TCR genes (which occurs immediately after the pro-T2 stage).

The effect of cotinine or cigarette smoke co-administration on the formation of O6-methylguanine adducts in the lung and liver of A/J mice treated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)

4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific nitrosamine, induces lung adenomas in A/J mice, following a single intraperitoneal (i.p.) injection. However, inhalation of tobacco smoke has not induced or promoted tumors in these mice. NNK-induced lung tumorigenesis is thought to involve O6-methylguanine (O6MeG) formation, leading to GC-->AT transitional mispairing and an activation of the K-ras proto-oncogene in the A/J mouse. NNK can be metabolized by several different cytochromes P450, resulting in a number of metabolites. Formation of the promutagenic DNA adduct O6MeG is believed to require metabolic activation of NNK by cytochrome P450-mediated alpha-hydroxylation of the methylene group adjacent to the N-nitroso nitrogen to yield the unstable intermediate, methanediazohydroxide. Nicotine, cotinine (the major metabolite of nicotine), and aqueous cigarette tar extract (ACTE) have all been shown to effectively inhibit metabolic activation of NNK to its mutagenic form, most likely due to competitive inhibition of the cytochrome P450 enzymes involved in alpha-hydroxylation of NNK. The objective of the current study was to monitor the effects of cotinine and cigarette smoke (CS) on the formation of O6MeG in target tissues of mice during the acute phase of NNK treatment. To test the effect of cotinine, mature female A/J mice received a single intraperitoneal injection of NNK (0, 2.5, 5, 7.5, or 10 mumole/mouse) with cotinine administered at a total dose of 50 mumole/mouse in 3 separate i.p. injections, administered 30 min before, immediately after, and 30 min after NNK treatment. To test the effect of whole smoke exposure on NNK-related O6MeG formation, mice were exposed to smoke generated from Kentucky 1R4F reference cigarettes at 0, 0.4, 0.6, or 0.8 mg wet total particulate matter/liter (WTPM/L) for 2 h, with a single i.p. injection of NNK (0, 3.75, or 7.5 mumole/mouse) midway through the exposure. Cigarette smoke alone failed to yield detectable levels of O6MeG. The number of O6MeG adducts following i.p. injection of NNK was significantly (p < 0.05) reduced in both lung and liver by cotinine and by cigarette smoke exposure. Our results demonstrate that NNK-induced O6MeG DNA adducts in A/J mice are significantly reduced when NNK is administered together with either cotinine, the major metabolite of nicotine, or the parental complex mixture, cigarette smoke.

Prevalence of suicide ideation and suicide attempts in nine countries

BACKGROUND

There are few cross-national comparisons of the rates of suicide ideation and attempts across diverse countries. Nine independently conducted epidemiological surveys using similar diagnostic assessment and criteria provided an opportunity to obtain that data.

METHODS

Suicide ideation and attempts were assessed on the Diagnostic Interview Schedule in over 40000 subjects drawn from the United States, Canada, Puerto Rico, France, West Germany, Lebanon, Taiwan, Korea and New Zealand.

RESULTS

The lifetime prevalence rates/100 for suicide ideation ranged from 2.09 (Beirut) to 18.51 (Christchurch, New Zealand). Lifetime prevalence rates/100 for suicide attempts ranged from 0.72 (Beirut) to 5.93 (Puerto Rico). Females as compared to males had only marginally higher rates of suicidal ideation in most countries, reaching a two-fold increase in Taiwan. Females as compared to males had more consistently higher rates for suicide attempts, reaching a two- to three-fold increase in most countries. Suicide ideation and attempts in most countries were associated with being currently divorced/separated as compared to currently married.

CONCLUSIONS

While the rates of suicide ideation varied widely by country, the rates of suicide attempts were more consistent across most countries. The variations were only partly explained by variation in rates of psychiatric disorders, divorce or separation among countries and are probably due to cultural features that we do not, as yet, understand.