Intravenous delivery of naked plasmid DNA for in vivo cytokine expression

We previously demonstrated that electroporation-mediated cytokine gene delivery into muscle is an effective approach for long-term systemic delivery of cytokines. Here we show that hydrodynamics-based gene delivery into mice by intravenous administration of naked plasmid DNA is a more efficient procedure for expressing cytokines in vivo. A large volume of Ringer's solution containing an interleukin-10 (IL-10) expression plasmid pCAGGS-IL10 was rapidly injected into the tail vein of mice. Serum IL-10 levels increased in a dose-dependent manner with a saturation level (50.8 +/- 12.1 microg/ml) 10,000-fold higher than we obtained by the electroporation-mediated method. High levels of serum IL-10 were sustained for at least 2 weeks following a single injection. These results demonstrate that hydrodynamics-based gene delivery could induce sustained high-level expression of cytokines, which would be useful for further studies of cytokine function in vivo and the development of novel immunotherapeutic strategies for systemic cytokine gene therapy.

Skin-targeted gene transfer using in vivo electroporation

The skin is an important target for gene transfer because of its easy accessibility. Using plasmid DNA expressing rat erythropoietin (pCAGGS-Epo) as the vector, we previously demonstrated long-term Epo delivery in rats by muscle-targeted gene transfer using in vivo electroporation. Here we examined whether this electroporation approach could be applied to gene delivery in rat skin. To optimize gene transfer, we tested the efficiency of skin-targeted Epo gene transfer with three types of electrodes at three different electrode voltages. Each rat was injected intradermally with a total of 800 microg of pCAGGS-Epo, in the abdominal area. Plate-and-fork-type electrodes were effective for Epo delivery by skin-targeted gene transfer at low voltages (12 approximately 24 V). The vector-derived Epo mRNA was expressed only at the DNA injection site. The Epo gene was expressed in a dose-dependent manner, the expression persisted for 7 weeks, and hematocrit levels were increased for 11 weeks. Skin injection with pCAGGS-lacZ showed lacZ gene expression in the epidermis on day 1 after injection and in the subcutaneous muscle layer on day 7. Slight skin damage due to the gene transfer procedure was evident on day 1, but absent by day 7. These results demonstrate that skin-targeted pCAGGS-Epo transfer by in vivo electroporation at low voltage is a useful procedure for the short-term delivery of Epo.

[Clinical utility and safety of diagnostic thoracoscopy]

The increasing use of thoracoscopy performed under local anesthesia has made contributions to the diagnosis of pleural disease with effusion. During the past 7 years, we have performed 100 such thoracoscopy procedures using a flexible fiberoptic bronchoscope. On the basis of our clinical findings, we are able to discuss the utility and safety of this procedure. The causes of pleural effusion were carcinomatous pleurisy in 72 cases, tuberculosis pleurisy in 15 cases, infection without tuberculosis in 4 cases, malignant pleural mesothelioma in 8 cases and one case of asbestosis. The success rate of thoracoscopic pleural biopsies were 97% for carcinomatous pleurisy, 100% for malignant pleural mesothelioma and 86% for tuberculosis pleurisy. This procedure was performed with no serious effect on blood pressure, oxygen saturation, monitored ECG or BGA data, and with no serious complications. Therefore, we concluded that this method is very useful for the diagnosis of pleural effusions and has few complications.

Altered psychomotor behaviors in mice lacking pituitary adenylate cyclase-activating polypeptide (PACAP)

Pituitary adenylate cyclase-activating polypeptide (PACAP) has been conserved remarkably during evolution and is widely expressed in the mammalian brain. In Drosophila, mutation of the PACAP homologue results in behavioral defects, including impaired olfaction-associated learning and changes in ethanol sensitivity. Here, we report the generation of mice lacking the PACAP gene (PACAP(-/-)). PACAP(-/-) mice were born in the expected Mendelian ratios but had a high early-mortality rate. The surviving adult PACAP(-/-) mice displayed remarkable behavioral changes; they exhibited hyperactive and explosive jumping behaviors in an open field, increased exploratory behavior, and less anxiety in the elevated plus maze, emergence, and novel-object tests. Analysis of PACAP(-/-) mice brains revealed that the serotonin metabolite 5-hydroxyindoleacetic acid was slightly decreased in the cortex and striatum compared with wild-type mice. The present study provides evidence that PACAP plays a previously uncharacterized role in the regulation of psychomotor behaviors.

Tissue-specific autoregulation of the stat3 gene and its role in interleukin-6-induced survival signals in T cells

Signal transducer and activator of transcription 3 (STAT3) mediates signals of various growth factors and cytokines, including interleukin-6 (IL-6). In certain IL-6-responsive cell lines, the stat3 gene is autoregulated by STAT3 through a composite IL-6 response element in its promoter that contains a STAT3-binding element (SBE) and a cyclic AMP-responsive element. To reveal the nature and roles of the stat3 autoregulation in vivo, we generated mice that harbor a mutation in the SBE (stat3(mSBE)). The intact SBE was crucial for IL-6-induced stat3 gene activation in the spleen, especially in the red pulp region, the kidney, and both mature and immature T lymphocytes. The SBE was not required, however, for IL-6-induced stat3 gene activation in hepatocytes. T lymphocytes from the stat3(mSBE/mSBE) mice were more susceptible to apoptosis despite the presence of IL-6 than those from wild-type mice. Consistent with this, IL-6-dependent activation of the Pim-1 and junB genes, direct target genes for STAT3, was attenuated in T lymphocytes of the stat3(mSBE/mSBE) mice. Thus, the tissue-specific autoregulation of the stat3 gene operates in vivo and plays a role in IL-6-induced antiapoptotic signaling in T cells.

Evaluation of endoscopic and histopathological features of serrated adenoma of the colon

BACKGROUND AND STUDY AIMS

The aim of this study was to reveal the clinical features of serrated colonic adenoma by investigating its endoscopic features using a magnifying videoscope.

MATERIALS AND METHODS

68 colorectal serrated adenomas presented for colonoscopic examination were included in this study. A magnifying videoscope with a zoom ranging from x 1 to x 100 magnification was employed to observe the pit patterns of colonic lesions, and 39 of the serrated adenoma specimens were evaluated using this. Some pit patterns appeared as elongated oval and stellar-like orifices of the crypts; we termed these type which was detected III(SA) patterns. Other pit patterns showed a flower petal-like or pineal form, and this was termed a type IV(SA) pit pattern.

RESULTS

In the entire sample of serrated adenomas, 53 were of the protruded type, and 15 were superficial, for a protruded/superficial ratio of 3.5 : 1. The protruded type of serrated adenoma predominated in the distal portion. The superficial type was preferentially located in the proximal portion of the colon (P < 0.0001). Among the 13 superficial types in which the magnifying videoscope was used, all 13 showed the type III(SA) basic pit pattern. In these serrated adenomas of the superficial type, an additional IV(SA) pit pattern was found in 23.1% (3/13), which was detected in 53.8% (14/26) in the protruded type. Small serrated adenomas measuring less than 10 mm in diameter were preferentially mild to moderate atypia (odd's ratio = 15.9, P = 0.0216).

CONCLUSION

The pit pattern may prove useful for the endoscopic diagnosis of serrated adenoma. Furthermore, endoscopic treatment is indicated for serrated adenoma; in particular those of 10 mm or more in diameter should be treated because of the possibility of high-grade glandular intraepithelial neoplasia.

Functional and evolutionary relationship between arginine biosynthesis and prokaryotic lysine biosynthesis through alpha-aminoadipate

Our previous studies revealed that lysine is synthesized through alpha-aminoadipate in an extremely thermophilic bacterium, Thermus thermophilus HB27. Sequence analysis of a gene cluster involved in the lysine biosynthesis of this microorganism suggested that the conversion from alpha-aminoadipate to lysine proceeds in a way similar to that of arginine biosynthesis. In the present study, we cloned an argD homolog of T. thermophilus HB27 which was not included in the previously cloned lysine biosynthetic gene cluster and determined the nucleotide sequence. A knockout of the argD-like gene, now termed lysJ, in T. thermophilus HB27 showed that this gene is essential for lysine biosynthesis in this bacterium. The lysJ gene was cloned into a plasmid and overexpressed in Escherichia coli, and the LysJ protein was purified to homogeneity. When the catalytic activity of LysJ was analyzed in a reverse reaction in the putative pathway, LysJ was found to transfer the epsilon-amino group of N(2)-acetyllysine, a putative intermediate in lysine biosynthesis, to 2-oxoglutarate. When N(2)-acetylornithine, a substrate for arginine biosynthesis, was used as the substrate for the reaction, LysJ transferred the delta-amino group of N(2)-acetylornithine to 2-oxoglutarate 16 times more efficiently than when N(2)-acetyllysine was the amino donor. All these results suggest that lysine biosynthesis in T. thermophilus HB27 is functionally and evolutionarily related to arginine biosynthesis.

Stat3 in thymic epithelial cells is essential for postnatal maintenance of thymic architecture and thymocyte survival

This study describes abnormalities of the thymus in mice in which the Stat3 gene has been specifically disrupted behind the keratin 5 promoter. In these mice, virtually all of the thymic epithelial cells (TEC) were deficient for Stat3 activation. Adult mutant mice developed severe thymic hypoplasia, which included alterations in the cortical TEC architecture that coincided with the loss of thymocytes. Even during the asymptomatic period of preadolescence, these mice exhibited a higher susceptibility of the thymus to suboptimal doses of dexamethasone or gamma-irradiation, while their thymocytes per se were no more sensitive than controls. These results indicate that Stat3 in TEC plays an essential role in maintaining thymic architecture and thymocyte survival.

Diffusion of nodal signaling activity in the absence of the feedback inhibitor Lefty2

The role of Lefty2 in left-right patterning was investigated by analysis of mutant mice that lack asymmetric expression of lefty2. These animals exhibited various situs defects including left isomerism. The asymmetric expression of nodal was prolonged and the expression of Pitx2 was upregulated in the mutant embryos. The absence of Lefty2 conferred on Nodal the ability to diffuse over a long distance. Thus, Nodal-responsive genes, including Pitx2, that are normally expressed on the left side were expressed bilaterally in the mutant embryos, even though nodal expression was confined to the left side. These results suggest that Nodal is a long-range signaling molecule but that its range of action is normally limited by the feedback inhibitor Lefty2.

A single intradermal administration of soluble leishmanial antigen and plasmid expressing interleukin-12 protects BALB/c mice from Leishmania major infection

In murine leishmaniasis, the induction of the T-helper type 1 (Th1) response contributes to infection resistance, whereas the establishment of the Th2 response makes the mice susceptible to infection. Interleukin-12 (IL-12) plays a pivotal role in the diversification of immune responses to the Th1 type. In this study, we tested whether the co-administration of IL-12 expression plasmid which compose p35 and p40 subunits and soluble leishmanial antigen (SLA) will skew the susceptible BALB/c mice to Th1 response and protect from leishmaniasis. When the mice were intradermally injected with the combination of IL-12 plasmid and SLA 7 days prior to the challenge with 1x10(6) promastigotes of Leishmania major, the local lesions completely healed and the parasite burden in the local lymph nodes significantly decreased. The cured mice attained long-term immunity, and were resistant to any subsequent rechallenge of the lethal dose of the parasite. The protective effect was associated with the development of a Th1 response, as demonstrated by the enhanced level of antigen-specific interferon-gamma (IFN-gamma) and dominant production of IgG2a in the serum. In contrast, the administration of empty plasmid plus SLA or IL-12 plasmid alone failed to protect the disease and shape the Th1 response. Furthermore, the protective efficiency induced by the vaccination was clearly prevented by the injection of either neutralizing anti-IL-12 mAb or anti-IFN-gamma mAb. The IL-12 expression plasmid is thus an effective adjuvant for the elicitation of a protective Th1 response against leishmaniasis and is therefore, considered to be appropriate for vaccinations that require the induction of Th1 type immunity.

Ancestral residues stabilizing 3-isopropylmalate dehydrogenase of an extreme thermophile: experimental evidence supporting the thermophilic common ancestor hypothesis

Ancestral amino acid residues were inferred for 3-isopropylmalate dehydrogenase (IPMDH), and were introduced into the enzyme of an extreme thermophile, Sulfolobus sp. strain 7. The thermostability of the mutant enzymes was compared with that of the wild type enzyme. At least five of the seven mutants tested showed higher thermal stability than the wild type IPMDH. The results are compatible with the hyperthermophilic universal ancestor hypothesis. The results also provide a new method for designing thermostable enzymes. The method only relies on the first dimensional structures of homologous enzymes that can be obtained from genetic databases.

Enhanced effect of sulfonylurea (SU) in copolymer comprising a sugar moiety and SU derivative as double ligands on insulin secretion from MIN6 cells

Copolymers composed of sulfonylurea (SU) as an antagonist of ATP-sensitive K+ channel and sugar moieties as double ligands were synthesized. Insulin secretion from MIN6 cells (insulinoma cell line) in contact with the copolymers was evaluated. MIN6 cells attached to the poly(N-p-vinylbenzyl-D-maltonamide-co-SU) [P(VMA-co-SU)]-coated dishes were in the more aggregated form as compared to other polymer-coated surfaces. By introducing SU into the sugar bearing homopolymer, an enhanced effect on insulin secretion from MIN6 cells was observed due to the specific interaction between SU ligands and SU receptors on the beta-cell membrane. P(VMA-co-SU) composed of SU and non-reducing glucose moieties demonstrated enhanced insulin secretion from MIN6 cells and faster proliferation of MIN6 cells as compared to poly(N-p-vinylbenzyl-D-lactonamide-co-SU) [P(VLA-co-SU)] probably owing to the glucose transporters presence on the MIN6 cell membrane. Insulin secretion from MIN6 cells pretreated with diazoxide as an agonist of ATP-sensitive K+ channel was suppressed.

Enhanced green fluorescent protein as a useful tag for rapid identification of homozygous transgenic mice

We developed a technique that simplifies the process of confirming homozygous transgenics at preimplantation stages, which are the earliest stages used in test breeding, using enhanced green fluorescent protein as a tag. All the blastocysts obtained by mating with the combination of Tg/Tg male (homozygous for transgene) x +/+ female exhibited fluorescence.

cDNA array hybridization reveals cardiac gene expression in acute ischemic murine hearts

PURPOSE

Although cDNA array technique has recently become available in the cardiovascular field, it has not yet been established what kind of genes in the myocardium are expressed by acute ischemia. Since many substances contribute to the pathophysiology of acute ischemic hearts, we investigated transcription responses of murine hearts to ischemia using cDNA array representing 18,376 genes.

METHODS AND RESULTS

In 29 male mice, we ligated the proximal site of the left coronary artery for 60 min. In 14 mice, we performed the sham operation without the ligation of the left coronary artery. After 60 min, the hearts were excised to obtain mRNA, and we performed cDNA array analysis. In 18,376 cDNA, 2 known genes were upregulated over 10-fold, 11 known genes were upregulated 5.0- to 9.9-fold, and 32 unknown genes were upregulated over 5.0-fold compared to sham-operated controls. In contrast, 11 known genes and 7 unknown genes were downregulated to levels below 0.2-fold. For 9 of the 13 known genes of which expression was increased as analyzed by cDNA array, subsequent Northern blot analysis also revealed an increase in expression.

CONCLUSION

Using cDNA array analysis we found that cardiac expression of 24 known and 39 unknown genes was modulated by acute ischemic stress, and appeared to be related to the pathophysiology of ischemic hearts. These results show that cDNA array analysis may provide a new molecular insight to the pathophysiology of acute ischemic hearts.

IL-12 plays a pathologic role at the inflammatory loci in the development of diabetes in NOD mice

Accumulating evidence suggests that CD4(+)T helper type 1 (Th1) cells play a major role in the development of insulin-dependent diabetes mellitus (IDDM) in the non-obese diabetic (NOD) mouse model. Interleukin (IL)-12 is a potent immunoregulatory molecule that is a key determinant of T-cell differentiation into Th1 cells, and has been implicated in the development of IDDM. To investigate the role of IL-12 that is locally produced by islet-infiltrating cells in the development of IDDM, we generated transgenic NOD mice in which the IL-12 p40 homodimer, a natural antagonist of IL-12, was produced exclusively in islets without affecting the levels of IL-12 p40 in the systemic circulation. We found that the incidence of diabetes was significantly reduced in these transgenic mice. These results clearly demonstrate that IL-12 locally produced by islet-infiltrating cells plays a critical role in the development of IDDM.

Long-term production of erythropoietin after electroporation-mediated transfer of plasmid DNA into the muscles of normal and uremic rats

The anemia associated with chronic renal failure is one of the best target diseases for erythropoietin (Epo) gene transfer. We previously reported a short-term (1 month) study of continuous rat Epo delivery by muscle-targeted gene transfer of plasmid DNA expressing rat Epo (pCAGGS-Epo) using in vivo electroporation in normal rats. Here, we performed a long-term pharmacokinetic study of continuous Epo delivery by this method in normal rats and uremic five-sixths nephrectomized rats. In normal rats, Epo gene expression and sufficient erythropoiesis occurred with Epo gene transfer in a dose-dependent manner, and persisted for at least 11 weeks. Repeated administration of the plasmid DNA effectively produced erythropoiesis. Similar erythropoiesis was observed in the uremic rats, and persisted for more than 15 weeks. Both normal and uremic rats showed a significant decrease in platelet count. Moreover, the uremic rats showed Epo-induced hypertension, which is the major side-effect of recombinant human Epo. These results demonstrate that muscle-targeted pCAGGS-Epo transfer by in vivo electroporation is a useful procedure for the long-term continuous delivery of Epo in both normal and uremic rats.

Human LT-alpha-mediated resistance to autoimmune diabetes is induced in NOD, but not NOD-scid, mice and abrogated by IL-12

Systemic administration of human lymphotoxin-alpha (hLT-alpha) made NOD mice resistant not only to spontaneous autoimmune type 1 diabetes mellitus but also to cyclophosphamide (CY)-induced diabetes and diabetes transfer by diabetic NOD spleen cells (triple resistance). In this study we analyzed the mechanisms of hLT-alpha-induced resistance, focusing on (1) hLT-alpha-induced resistance in the pancreatic beta cell, (2) CY-resistant suppressor cells, (3) suppression of induction or function of effector cells for beta cell destruction, or (4) others. To examine the first possibility in vitro, a NOD-derived beta cell line (MIN6N) was pretreated with hLT-alpha and then mixed with diabetic NOD spleen cells and MIN6N cell viability was measured. Treatment with hLT-alpha did not protect MIN6N cells but rather enhanced cytotoxicity. Next NOD-scid mice were pretreated with hLT-alpha and then transferred with diabetic NOD spleen. All the recipients developed diabetes. These results excluded the first possibility. The second possibility was also excluded by a cotransfer experiment, in which diabetic NOD spleen cells were cotransferred to NOD-scid mice with nontreated or hLT-alpha-treated nondiabetic NOD spleens. There was no significant difference in diabetes incidence between the two groups. To observe the third possibility, spleen cells of hLT-alpha-treated triple-resistant NOD mice were transferred to NOD-scid mice. Diabetes developed in the recipients, although the onset of diabetes was slightly delayed. Finally, hLT-alpha-treated triple-resistant NOD mice developed diabetes 1 week after daily IL-12 treatment. In summary, hLT-alpha administration made NOD mice resistant to effector cells for beta cell destruction. This resistance was induced in NOD, but not in NOD-scid, mice, indicating that lymphocytes were obligatory for the resistance. However, it was not mediated by transferable suppressor cells. Because effector cells were present in hLT-alpha-treated NOD spleen and the resistance was abrogated by IL-12 treatment, it is speculated that hLT-alpha treatment may have changed a local cytokine balance protective from beta cell destruction.

Structure of the mouse glutamate decarboxylase 65 gene and its promoter: preferential expression of its promoter in the GABAergic neurons of transgenic mice

GABA is synthesized by glutamate decarboxylase (GAD), which has two forms, GAD65 and GAD67. To elucidate the molecular mechanisms of mouse GAD65 (mGAD65) gene expression, we isolated and characterized the mGAD65 gene. The mGAD65 gene was found to be divided into 16 exons and spread over 75 kb. The sequence of the first exon and the 5'-flanking region indicated the presence of potential neuron-specific cis-regulatory elements. We used transgenic mice to examine the expression pattern conferred by a 9.2-kb promoter-proximal DNA fragment of the mGAD65 gene fused to the bacterial lacZ reporter gene. Transgenic mice showed high beta-galactosidase activity specifically in brain and testis. They also showed characteristic patterns of transgene expression in olfactory bulb, cerebellar cortex, and spinal cord, a similar expression pattern to that of endogenous mGAD65. However, no transgene expression was observed in the ventral thalamus or hypothalamus, in which high mGAD65 gene expression levels have been observed. These results suggest that the 9.2-kb DNA fragment of the mGAD65 gene is associated with its tissue-specific expression and its targeted expression in GABAergic neurons of specific brain regions but that additional regulatory elements are necessary to obtain fully correct expression.

Clinical studies on bronchial asthma caused by contact with hamsters

Bronchial asthma induced by contact with hamsters and other small rodents is receiving higher attention from the medical profession not only because of the problem of laboratory animal allergies (LAA), but also because of increasing household allergens for asthma, since keeping these pets has become more common in Japanese homes. The present report describes our studies on the backgrounds of nine patients with asthma who kept Dzungarian Dwarf hamsters as household pets. The following features were recognized among patients with bronchial asthma induced by contact with hamsters: 1) earlier onset of symptoms than for keeping other household pets, at an average of 14.7 months or within 12 months in 78% of the cases following the start of pet keeping; 2) adults ranging from their late 30s to 40s who have children of primary school age; 3) dwelling in apartments; 4) relatively high level of serum IgE and ECP; 5) positive for both immediate and late type asthmatic responses on an inhaling induction test; and 6) rapid remission after the cessation of pet keeping.

Suppression of airway inflammation by theophylline in adult bronchial asthma

BACKGROUND

Chronic continuous airway inflammation caused by eosinophils has been noted to play critical roles in the pathophysiology of bronchial asthma, in addition to reversible obstruction and hypersensitivity of the respiratory tract. Therefore, suppression of chronic airway inflammation has become more important in asthma treatment. Although theophylline has been a conventionally used bronchodilator, it has been recently reported to have concurrent anti-inflammatory effects.

OBJECTIVE

Accordingly, we studied the effects of a slow-release theophylline preparation, Theolong, on airway inflammation.

METHODS

Administration of Theolong 400 mg/day to 24 patients with mild or moderate asthma and measuring eosinophil cationic protein (ECP), a marker of airway inflammation, and eosinophils in sputum and peripheral blood at 4 and 8 weeks.

RESULTS

As a result, sputum ECP, serum ECP and sputum eosinophil count (%) were significantly lowered after 4 and 8 weeks.

CONCLUSION

Thus, in the theophylline-administered group, slow-release theophylline, Theolong, was effective in treating asthma, with anti-inflammatory effects on inflammatory cells besides its bronchodilator action.

IL-12-encoding plasmid has a beneficial effect on spontaneous autoimmune disease in MRL/MP-lpr/lpr mice

Systemic lupus erythematosus (SLE) is characterized by immune abnormalities explained by the overproduction of Th(2)cytokines such as autoantibody production and polyclonal B cell activation. We examined the effect of administering a DNA plasmid encoding IL-12 on the lupus-like disease of MRL/MP-lpr/lpr (MRL/lpr) mice. Treatments were delivered intramuscularly every 4 weeks, starting at 4 weeks of age. This intervention significantly inhibited the accumulation of CD4(-)CD8(-)T cells, and reduced lymphadenopathy and splenomegaly. A significant decrease in serum IgG anti-DNA autoantibody titers was observed, and plasmid IL-12 therapy was also associated with a reduction in the proteinuria and glomerulonephritis characteristic of this disease. Serum IFN-gamma level was increased by inoculating IL-12 encoding plasmid, suggesting that the cytokine balance was skewed towards Th(1). The clinical implications of this suppression of autoimmune disease are also discussed.

High-dose chemotherapy with peripheral blood stem cell transplantation for advanced testicular cancer

BACKGROUND

The present study was performed in order to investigate the efficacy and safety of high-dose chemotherapy for the treatment of patients with advanced testicular cancer.

METHODS

Seven patients were treated with high-dose carboplatin, etoposide and cyclophosphamide followed by peripheral blood stem cell transplantation. Five patients received one cycle and two patients received two cycles of the high-dose chemotherapy.

RESULTS

Of the seven patients, one achieved a complete response and four achieved partial responses with markers negative. As a result of subsequent surgery for residual tumors, three of the four partial responders showed no residual cancer cells. One patient who did not undergo surgery received radiotherapy after the high-dose chemotherapy and the residual tumors disappeared. All five patients who had either a complete or partial response are still alive and without evidence of disease at 12, 27, 30, 37 and 40 months. One patient is alive with disease at 7 months and one died of progressive disease at 6 months. The hematologic recovery after high-dose chemotherapy was rapid and non-hematologic toxicities were usually mild and manageable.

CONCLUSIONS

High-dose chemotherapy followed by peripheral blood stem cell transplantation is safe and effective for use in patients with far-advanced testicular cancer, particularly when the high-dose chemotherapy is conducted as the initial treatment. Further larger and long-term follow-up studies are needed to define the role of high-dose chemotherapy on testicular cancer.

Spermatocyte-specific gene excision by targeted expression of Cre recombinase

Transgenic mice carrying the coding sequence of the Cre recombinase, whose expression was driven by the spermatocyte-specific Pgk-2 promoter, were generated. These mice were crossed with a reporter transgenic line, which produces beta-galactosidase depending on the occurrence of loxP-mediated DNA recombination. When DNA of the offspring was analyzed by PCR and Southern blotting, signals that appear after the recombination were detectable only in the testis. Histochemical analyses revealed that beta-galactosidase was present in spermatocytes and spermatogenic cells at later differentiation stages. However, the distribution of the protein was not uniform in all spermatocytes. Analyses of genomic DNA of the next generation indicated that recombination took place in about 70% of spermatogenic cells. From these results, we concluded that this transgenic line possessing Pgk-2-driven expression of the Cre recombinase should be useful for identifying spermatogenic genes that function at or after the spermatocyte stage.