Transgenic rescue from embryonic lethality and renal carcinogenesis in the Eker rat model by introduction of a wild-type Tsc2 gene

We recently reported that a germ-line insertion in the rat homologue of the human tuberous sclerosis gene (TSC2) gives rise to dominantly inherited cancer in the Eker rat model. In this study, we constructed transgenic Eker rats with introduction of a wild-type Tsc2 gene to ascertain whether suppression of the Eker phenotype is possible. Rescue from embryonic lethality of mutant homozygotes (Eker/Eker) and suppression of N-ethyl-N-nitrosourea-induced renal carcinogenesis in heterozygotes (Eker/+) were both observed, defining the germ-line Tsc2 mutation in the Eker rat as embryonal lethal and tumor predisposing mutation. To the best of our knowledge, this is the first report of rescue from a naturally occurring dominantly inherited cancer. This transgenic rescue system will be useful to analyze Tsc2 gene function, its relation to tumorigenesis in vivo, and genetic-environmental interactions in carcinogenesis.

Viability of transgenic rat embryos after freezing and thawing

In-vivo viability of frozen-thawed embryos derived from transgenic rats, as well as the transmission and the expression of transgenes in the resultant newborn rats, was investigated. Three strains of transgenic rats, carrying human growth hormone gene connected downstream to the promoter region of the bovine alpha-lactalbumin gene (alpha LA/hGH), bovine beta-casein gene (beta CN/hGH) or bovine alpha-S1 casein gene (alpha S1CN/hGH), were used. Two-cell stage embryos (non-transgenic Wistar female x heterozygous transgenic male) were placed in 10% (v/v) dimethylsulfoxide (DMSO) solution and cooled from -7 to -30 degrees C at -0.5 degree C/min before being plunged into liquid nitrogen. After 2 to 4 years storage, the embryos were thawed by rapid warming. The intact embryos were transferred into the oviducts of Day 1 pseudopregnant recipients. The postthaw survival rate of frozen embryos was high in all 3 transgenic strains (88 to 92%), which was similar to that of control (non-transgenic) frozen embryos (95%). Development to newborn rats following transfer of embryos derived from the 3 strains (64 to 68%) was also similar to that of control embryos (60%). These transgenes (alpha LA/hGH, beta CN/hGH and alpha S1CN/hGH) were detected in the DNA extracts from tail tissue of the newborn rats, but the transmission rates (41, 23 and 32%, respectively) were lower than 50% which is expected in the Mendelian fashion. In a transgenic line carrying alpha S1CN/hGH, hGH levels of secretion into the milk of transgenic newborn rats derived from frozen-thawed embryos and her transgenic offspring were the same mg/ml-level as that of their founder rat. Two-step freezing of embryos derived from transgenic rats was therefore an effective method for the long-term cryopreservation of transgene.

Overexpression of c-myc induces apoptosis at the prophase of meiosis of rat primary spermatocytes

Transgenic rats expressing the rat c-myc gene under the control of the human metallothionein II A promoter were produced. We found that the female transgenic rats were fertile, but that the male transgenic rats were sterile. Atrophy of the seminiferous tubules and depletion of sperm were observed in the sterile male testes. The expression of differential stage-specific mRNAs, including those of the c-kit receptor proto-oncogene, meiotic heat-shock protein 70 gene, acrosin gene, and transition protein 1 gene, was analyzed by the reverse transcriptase-polymerase chain reaction during spermatogenesis. The results suggested that spermatogenesis in these sterile rats were arrested at the prophase of meiosis in the primary spermatocytes. We found that apoptotic DNA fragmentation occurred in primary spermatocytes of the sterile transgenic rats. These results suggest that overexpression of the c-myc gene induces apoptosis at the prophase meiosis of the primary spermatocytes thereby causing male sterility in the c-myc transgenic rats.

Transgene expression in mammary glands of newborn rats

Transgene expression in the mammary glands of newborn rats was studied to establish an early selection system for transgenic animals producing exogenous proteins in their milk during lactation. A fusion gene composed of the bovine alpha S1 casein gene promoter and the human growth hormone gene was microinjected into rat embryos. Transgenic lines that produced human growth hormone in their milk were established and used in this study. Immediately after birth, and without any hormone treatment, human growth hormone was found in the extracts of mammary glands from both male and female rats derived from the line secreting human growth hormone in their milk. The expression of the transgene in mammary glands of newborn rats was also detected by the presence of human growth hormone mRNA. Nontransgenic newborn rats did not express the human growth hormone gene in their mammary glands, while the mRNA for rat alpha casein, an endogenous milk protein, was found in all mammary glands from both transgenic and nontransgenic neonates. These results show that analyzing the expression of transgenes in the mammary glands of neonates is a valuable tool to select the desired transgenic animals and to shorten the selection schedules establishing the transgenic animals.

Activation of glutathione transferase P gene by lead requires glutathione transferase P enhancer I

Glutathione transferase P (GST-P) is specifically induced in rat liver and kidney by lead cation. The increase of GST-P mRNA after lead administration is blocked by actinomycin D, suggesting that GST-P production by lead is regulated at the transcriptional level. To further determine which part of the flanking region of the GST-P gene has the lead-responsive cis-element in vivo, we utilized transgenic rats with five different constructs having GST-P and/or chloramphenicol acetyl-transferase coding sequence. We studied the effect of lead on these transgenic rats and on transfected NRK (normal rat kidney) cells and found that GST-P induction by lead is indeed regulated at the transcriptional level and that the GST-P enhancer I (GPEI) enhancer is an essential cis-element required for the activation of the GST-P gene by lead. GPEI consists of two AP-1 (c-Jun/c-Fos heterodimer) site-like sequences that are palindromically arranged and can bind AP-1, c-jun mRNA in the liver increased after lead administration and GST-P, and c-Jun had patchy expression in the same hepatocytes 24 h after lead exposure. These results suggest that activation of the GST-P gene by lead is mediated in major part by enhancer GPEI and that AP-1 may be involved at least partially. GPEI has been shown to have essential sequence information for the trans-activation of the GST-P gene during chemical hepatocarcinogenesis of the rat (Morimura, S., Suzuki, T., Hochi, S., Yuki, A., Nomura, K., Kitagawa, T., Nagatsu, I., Imagawa, M., and Muramatsu, M. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 2065-2068; Suzuki, T., Imagawa, M., Hirabayashi, M., Yuki, A., Hisatake, K., Nomura, K., Kitagawa, T., and Muramatsu, M. (1995) Cancer Res. 55, 2651-2655). The present study establishes that the same enhancer element does operate in the activation of the GST-P gene by lead regardless of the trans-activators involved.

Tissue-specific activation of tumor marker glutathione transferase P transgenes in transgenic rats

By means of transgenic rats, we have recently shown that the GPEI enhancer of the glutathione transferase P (GST-P) gene, which has two one-base-missmatched AP-1 sites locating palindromically with three-base spacing in between, is sufficient for conferring tumor-specific activation of the gene in vivo. It is noted that there is another consensus AP-1 site near the promoter of this gene. By using seven independent transgenic rats, bearing distinct areas of the GST-P gene that are connected to the chloramphenicol acetyltransferase (CAT) coding sequence, we analyzed CAT expression in various tissues (brain, lung, liver, kidney, spleen) in these transgenic rats. We found that the ECAT gene, which has sufficient of the upstream regulatory region (approx. 2.9 kb) of the gene containing GPEI, is trans-activated in the kidney and lung of transgenic rats in a similar manner to endogenous GST-P. When either the GPEI core sequence or the AP-1 site near the promoter is deleted, CAT expression decreases to almost background level. Substitution of the GPEI core or the AP-1 site near the promoter to this silent construct (5CATGPEIcore) reconstituted CAT expression in the transgenic rats. In these rats, CAT was expressed in the brain and lung rather than in the kidney, showing a somewhat different pattern from the endogenous GST-P. In the brain tissue of the 5CATGPEIcore transgenic rat, CAT was demonstrated in the glia cells, which is consistent with endogenous GST-P expression. These results suggest that a relatively long upstream region (approx. 2.9 kb) is required for tissue-specific expression of the GST-P gene and that GST-P expression in the brain may be regulated differently from its expression in other organs.

Identification of an enhancer responsible for tumor marker gene expression by means of transgenic rats

The glutathione transferase P (GST-P) gene is known for its specific expression during chemical hepatocarcinogenesis of the rat and is used as a tumor marker for hepatocellular carcinoma. We have shown recently that the upstream 2.9-kb region of the GST-P gene is sufficient for conferring tumor-specific expression of the gene in vivo (S. Morimura et al., Proc. Natl. Acad. Sci. USA, 90: 2065-2068, 1993). To further identify crucial sequence elements regulating the unique expression of this gene, we have established six independent lines of transgenic rats bearing distinct areas of the GST-P gene that are connected to the chloramphenicol acetyltransferase coding region and analyzed changes of the chloramphenicol acetyltransferase activity during the course of chemical hepatocarcinogenesis. We demonstrate here that the enhancer, glutathione transferase P enhancer I, that is located 2.5 kb upstream of the GST-P gene is required and sufficient for its tumor-specific expression of the gene among other controlling elements. This approach to transgene expression could be used to define other enhancers, the activity of which is dependent on cellular changes such as carcinogenesis, development, and differentiation.

Functions of milk protein gene 5' flanking regions on human growth hormone gene

Fragments containing 5' flanking regions of four bovine milk protein genes--alpha lactalbumin (b alpha LA), alpha S1 casein (b alpha S1CN), beta casein (b beta CN), kappa casein (b kappa CN)--and mouse whey acidic protein (mWAP) gene were prepared by PCR and ligated to human growth hormone (hGH) gene. These recombinant DNAs were microinjected into rat embryos to produce transgenic rats, and the functions of the 5' regions to direct secretion of hGH in the milk were tested. Although milk was obtained only in 5 of 19 mWAP/hGH rat lines, more than two-thirds of the rats carrying the other four DNAs produced milk. More than 80% of the lactated rats carrying b alpha LA/, b beta CN/, and mWAP/hGH, and 33% of the lactated b alpha S1CN/hGH rats secreted detectable amounts of hGH (> 0.05 microgram/ml) in the milk. In some rats, the hGH concentrations in the milk were comparable to or more than that of the corresponding milk protein in bovine milk. The ranges of hGH concentrations in the milk of b alpha LA/, b beta CN/, b alpha S1CN/, and mWAP/hGH rats were 1.13-4,360 micrograms/ml, 0.11-10,900 micrograms/ml, 86.8-6,480 micrograms/ml, and 6.87-151 micrograms/ml, respectively. HGH was also detected in the sera of these rats, and some abnormalities of growth and reproduction were observed. All but one virgin mWAP/hGH rat secreted up to 0.0722 microgram/ml of hGH in the serum, and more than half of them showed abnormal fat accumulations at their abdomen.(ABSTRACT TRUNCATED AT 250 WORDS)

[Treatment of unresectable non-small cell lung cancer (NSCLC) with carboplatin and chronic daily administration of oral etoposide]

CBDCA has only modest activity against NSCLC, but it is less toxic than cisplatin (CDDP). And CB DCA has a proven synergistic effect with etoposide. On the other hand, etoposide is schedule dependent and when give daily peros has activity against several tumors. So we conducted a trial to evaluate the efficacy of a combination of CBDCA and chronic daily administration of oral etoposide for previously untreated unresectable NSCLC. The treatment schedule consisted of CBDCA 400 mg/m2 on day 1 and chronic daily administration of oral etoposide of 50 mg/day/body for 21 consecutive days every 28 days. Twenty-nine of 36 enrolled patients were eligible. The response rate was 27.6% (95% confidence interval: 11.1-43.9%). The median survival time was 405 days. The primary toxicity was myelosuppression: leukopenia, neutropenia, anemia and thrombocytopenia of Grade 3 or 4 were 14.7%, 29.4%, 26.5%, and 5.9%, respectively. No bleeding episodes or toxic death were observed. Nonhematologic toxicity was slight, and there was no severe gastrointestinal toxicity. This combination was effective against NSCLC with tolerable toxicity and an "easily tolerated outpatient regimen".

Effect of chlorpromazine on mouse ambulatory activity sensitization caused by (+)-amphetamine

The development of sensitization to the ambulation-increasing effect of (+)-amphetamine (2.5 mg kg-1) was found to be dose-dependently inhibited when 1 or 2 mg kg-1 chlorpromazine was administered concomitantly, and the sensitization to (+)-amphetamine was almost completely suppressed when co-administered with 4 mg kg-1 chlorpromazine. Following a challenge dose of 2.5 mg kg-1 (+)-amphetamine, mice pretreated with (+)-amphetamine alone or with (+)-amphetamine plus 1 or 2 mg kg-1 chlorpromazine showed similar marked enhancement of the sensitization. However, mice that had been given (+)-amphetamine plus 4 mg kg-1 chlorpromazine displayed only slight enhancement of the effect compared with the activity level in saline-pretreated mice.

[Malignant lymphoma following operation and chemotherapy of small cell lung carcinoma]

A 57-year-old man was admitted with systemic lymphadenopathy. He had undergone resection for small cell lung carcinoma and received chemotherapy 6 years previously. A specimen of swollen lymph nodes showed malignant lymphoma. Surface marker analysis revealed the lymphoma to have the same characteristics as lymphoblastic lymphoma (LBL). He received combination chemotherapy, but marked resistance was recognized. His condition deteriorated rapidly and died. Having the characteristics of LBL on lymphoma at an older age and severe drug-resistance suggests that this lymphoma might have been a second malignancy due to preceding chemotherapy.

[Pharmacodynamics and therapeutic usage of recombinant human erythropoietin (SNB-5001) in animal models]

In mice, SNB-5001 released reticulocytes dose-dependently. In rats, rabbits and dogs given the same doses of SNB-5001, each dose-response curve of hemopoiesis almost showed parallelism. SNB-5001 induced nearly the same extent of hemopoiesis in these animals. After the hemopoiesis caused by SNB-5001, reticulocytes decreased within a week in both rats and dogs, but numbers of red blood cells (RBC) were higher than each control group for over 2 weeks in rats and for over 3 weeks in dogs. In polycythemic rats given excessive doses (200-5000 U/kg) of SNB-5001, blood volume increased, but blood pressure did not change. In the renal anemic rats produced by partial nephrectomy, dose-related and cumulative hemopoiesis were observed in both groups given SNB-5001 with different administration schedules (once a day for a week or once a week for 3 weeks). In the phrebotomized rats, SNB-5001 accelerated the recovery from the anemia induced by phrebotomy when given in a large quantity (6 ml/rat) and prevented the progressive anemia induced by intermittent phlebotomies when given in a small quantity (1 ml/rat x 3). SNB-5001 also improved the anemia caused by chronic inflammation in rats. However, increases of hemoglobin and hematocrit were smaller than that of RBC. Those results were caused by impaired release of iron from the reticuloendothelial system.

Serum calcium increases the incidence of arrhythmias during acetate hemodialysis

We investigated the occurrence of arrhythmias during maintenance acetate hemodialysis (HD) using a 24-hour continuous electrocardiogram recording system. Three of 22 patients showed augmented increases in both ventricular premature beats and supraventricular premature beats during HD. When we changed the dialysate from one with a Ca2+ concentration of 1.75 mmol/L (3.5 mEq/L), to one with a Ca2+ concentration of 1.25 mmol/L (2.5 mEq/L), the elevation of serum Ca2+ concentration during HD was abolished and the increases in both ventricular premature beats and supraventricular premature beats were significantly decreased. The elevation of serum Ca2+ concentration during HD might induce either extracellular or intracellular increase in Ca2+ concentration in the heart and elicit either reentry- or triggered-activity types of arrhythmias during HD. The present results indicate that the dialysate with a lower Ca2+ concentration is advisable to use in patients with underlying cardiac diseases.

Sensitization to ambulation-increasing effects of cocaine after repeated administration in mice--roles of dose and interval of administration as well as experimental environments

Effects of 5 subcutaneous injections of cocaine (COC) at 10, 20 or 40 mg/kg at intervals of 1 to 7 days were investigated by placing mice individually into tilting activity cages (20cm in diameter and 18 cm height). A progressive enhancement of the ambulation-increasing effect was noted for 3 to 4 hrs after each administration, showing marked sensitization (reverse tolerance). The enhancement of the effect progressed rapidly and the maximum sensitization was observed after the 3rd to 4th administration of 10 to 20 mg/kg at intervals of 3 to 7 days. The peak effect of the enhancement was of short duration. Sensitization lasted for at least one month. However, 40 mg/kg of COC produced stereotyped behaviors concurrent with preconvulsive signs which were also enhanced by serial administration. In contrast, pretreatment with COC in a narrow environment (glass jar, 5.5 cm in diameter and 15 cm height) did not cause the enhancement to the ambulation-increasing effect of the drug. Cross-sensitization was observed from COC to methamphetamine.

[Evaluation of chemotherapy of unresectable non-small cell lung cancer]

For this evaluation, a comparison was made of survival of 34 patients with non-small cell lung cancer who had undergone chemotherapy (Group B) with that of 38 patients without this chemotherapy (Group A). Group B had received neither radiotherapy for primary lesions nor bronchial artery infusion of anticancer drugs, and the chemotherapeutic regimen was CDDP + VDS or CDDP + VDS + MMC chemotherapy. MST of this group was significantly longer than that of Group A (4.5 months vs 7.3 months. P less than 0.01), but the PS features of the two groups differed significantly. A comparison was thus made of survival for PS 1-2 cases in both groups (Group A: 17 cases, Group B: 27 cases). MST of group A and B were 6.8 and 9.8 months, respectively (P less than 0.05). The efficacy of the treatment for prolonging survival in terms of age, sex, PS, histology, T factor, N factor and M factor was evaluated by multivariate analysis using the proportional hazard model of Cox. The results obtained indicated the chemotherapy significantly prolonged survival.

Comparison of sensitization to ambulation-increasing effects of cocaine and methamphetamine after repeated administration in mice

The effects of repeated (5 times) subcutaneous administration of cocaine (10, 20 or 40 mg kg-1) and methamphetamine (1, 2 or 4 mg kg-1) at 3-4 day intervals have been compared in mice placed individually into tilting activity cages. A progressive enhancement of the ambulation-increasing effect was noted for 3-4 h after each administration, indicating that sensitization occurred. This occurrence and the existence of an optimal dose producing sensitization were similar for both drugs. However, enhancement of the effect after cocaine progressed rapidly and maximum sensitization was observed earlier than after methamphetamine administration. Moreover, the higher doses of cocaine (40 mg kg-1) caused stereotypies concurrent with preconvulsive signs of short duration that were enhanced by serial administration. In contrast, methamphetamine caused a more progressive enhancement, but stereotypies with no preconvulsive signs were produced by the higher dose (4 mg kg-1). The respectively, effective doses for the development of enhancement suggested that cocaine was less potent than methamphetamine in producing sensitization. Cross-sensitization occurred between both drugs. Thus, sensitization to cocaine was distinct from that to methamphetamine due to differences in its rapidity, intensity, and the presence or absence of preconvulsive changes.

[Mitral flow dynamics in patients with hemodialysis: assessment with pulsed Doppler echocardiography]

We investigated transmitral flow dynamics before (B) and after (A) hemodialysis (HD). Pulsed Doppler echocardiography was performed in 15 patients (10 males and 6 females, with a mean age of 51) with neither valvular disease nor heart failure. After HD, systolic and diastolic pressure declined significantly to [156 +/- 27----135 +/- 24mmHg (p less than 0.01) and 84 +/- 16----75 +/- 15mmHg (p less than 0.02)] respectively. However, heart rate did not change. Doppler derived indexes were peak early filling velocity (E), peak filling during atrial contribution (A), early filling time velocity integral (IE), atrial time velocity integral (IA), and percent atrial contribution [IA/(IE + IA) x 100] (%A) There was a positive correlation between E and peak systolic stress (r = 0.437, p less than 0.05). Conclusion; In HD, early diastolic filling is dependent on preload. It is necessary to consider preload when diastolic function is assessed.

Renal anemia in polycystic kidney disease mouse

DBA/2FG-pcy mice developed the chronic renal failure by the progressive polycystic formation at five months old. Their bilaterally enlarged kidneys occupied about 15% of the body weight. It was about 9 times larger than the normal kidney of DBA/2N mice. A large number of various-sized cysts appeared in cortex and medulla of bilateral light-yellow kidneys of sponge-like shape. Blood urea nitrogen and creatinine increased. Red blood cells (746 +/- 39 x 10(4)/mm3), hemoglobin (8.8 +/- 0.4 g/dl) and hematocrits (31.1 +/- 1.5%) were lower than those of normal control mice. Serum erythropoietin level and reticulocytes did not increase. In addition, the treatment with exogenous erythropoietin improved the anemia in DBA/2FG-pcy mice. It was suggested that the anemia in DBA/2FG-pcy mice was due to the disorder of erythropoietin production caused by the progressive polycystic formation in kidneys.