Loss of fibroblast growth factor receptors is necessary for terminal differentiation of embryonic limb muscle

Early in embryogenesis, precursors of the limb musculature are generated in the somite, migrate to the limb buds and undergo terminal differentiation. Although myogenic differentiation in culture is affected by several growth factors including fibroblast growth factor (FGF), it remains uncertain whether migration and differentiation of myogenic cells in vivo are directly regulated by such growth factors. To investigate the roles of FGF signaling in the regulation of myogenesis both in the somite and the limb bud, mosaic chicken embryos were generated that consist of somitic cells carrying transgenes expressing one of the following: FGF1, FGF4, the FGF receptor type-1 (FGFR1) or its dominant negative mutant (delta FGFR1). Cells infected with virus producing FGF ligand migrated into the somatopleure without differentiating into myotomal muscle, but differentiated into muscle fibers when they arrived in the limb bud. In contrast, cells overexpressing FGFR1 migrated into the limb muscle mass but remained as undifferentiated myoblasts. Cells infected with the delta FGFR1-producing virus failed to migrate to the somatopleure but were capable of differentiating into myotomal muscle within the somites. These results suggest that the FGFR-mediated FGF signaling (1) blocks terminal differentiation of myogenic cells within the somite and (2) sustains myoblast migration to limb buds from the somite, and that (3) down-regulation of FGFRs or FGFR signaling is involved in mechanisms triggering terminal differentiation of the limb muscle mass during avian embryogenesis.

Polymerase chain reaction for the detection of Chlamydia psittaci in the feces of budgerigars

The polymerase chain reaction (PCR) targeting the ompA gene of Chlamydia psittaci was evaluated for its ability to detect chlamydiae in fecal specimens of budgerigars as compared with isolation procedures using cell culture and embryonated egg inoculations. Several procedures for PCR template DNA preparation were compared so as to determine their detection levels for chlamydiae propagated in cell culture in the presence of fecal materials. Tween-20 and proteinase K treatments followed by centrifugation of the template DNA were found to be an appropriate procedure for DNA preparation for primary PCR. Subsequent nested PCR was shown to detect 4.8 IFU/ml or 84 particles/ml of chlamydiae. Chlamydiae in 50 fecal specimens from apparently healthy budgerigars were examined by nested PCR and several other methods. Nested PCR detected chlamydiae at a higher rate (12/50, 24%) than the isolation procedure in embryonated eggs (6/50, 12%). Primary PCR combined with the isolation procedure in cell culture gave a detection rate (5/50, 10%) similar to that of isolation from embryonated eggs. Detection rates by primary PCR (1/50, 2%) and in cell culture (0%) were inferior to the other procedures.

Influence of hypertensive vascular changes in intratesticular arteries on spermatogenesis in SHRSP

1. The process of the spermatogenetic damage induced by hypertensive vascular changes was studied with stroke-prone spontaneously hypertensive rats (SHRSP). 2. In SHRSP, hypertensive changes in intratesticular arterioles developed from 19 weeks of age. 3. At 23 weeks of age, a severe reduction in the number of mature and immature spermatids was observed. 4. The transferrin concentration in testicular cytosol was decreased at 23 weeks of age, suggesting that Sertoli cell function in SHRSP had regressed. 5. In conclusion, it was suggested that the decline in Sertoli cell function as a result of hypertensive vascular changes is part of the mechanism whereby spermatogenic damage occurs in SHRSP.

Protective effects of manidipine on spermatogenesis in stroke-prone spontaneously hypertensive rats

1. We evaluated the protective effects of manidipine on spermatogenic damage induced by the hypertensive vascular changes in stroke-prone spontaneously hypertensive rats (SHRSP). 2. Blood pressure reached more than 250 mmHg in SHRSP at 15 weeks of age, and thereafter the hypertensive changes in testicular arterioles developed. Manidipine reduced both the blood pressure and the hypertensive vascular changes. 3. Although immature and mature spermatids greatly diminished in SHRSP at 23 weeks of age, manidipine could preserve almost normal spermatogenesis even at 23 weeks of age. Transferrin concentration in testicular cytosol, which was considered to be indicative of the Sertoli cell function, in SHRSP with manidipine administration was significantly higher than that in SHRSP with no treatment at 23 weeks of age. 4. In conclusion, manidipine could prevent the development of the hypertensive changes in intratesticular arterioles and maintain normal Sertoli cell function. As a result, manidipine protected spermatogenic damage in SHRSP.

A long-term receptor stimulation is requisite for angiotensin II-dependent DNA synthesis in vascular smooth muscle cells from spontaneously hypertensive rats

Angiotensin II stimulates DNA synthesis in aortic smooth muscle cells prepared from spontaneously hypertensive rats, with maximal levels detected 20 h after stimulation. Angiotensin II receptor antagonists inhibited the angiotensin II-induced DNA synthesis. In particular, the noncompetitive antagonist 2-ethoxy-1-[[2'(1 H-tetrazol-5-yl) biphenyl-4-yl]methyl]-1 H-benzimidazole-7-carboxylic acid (CV11974) was more effective than expected from its affinity for the angiotensin II receptor and its potency for inhibiting angiotensin II-induced increase in cytosolic free Ca2+ concentration 2-n-Butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1 H-tetrazol-5-yl)biphenyl-4-yl) methyl]imidazole, potassium salt (losartan), one of the antagonists, inhibited angiotensin II-induced DNA synthesis by 92% and 79%, even when added 2 and 4 h after angiotensin II stimulation, respectively. Angiotensin II also increases the mRNA of platelet-derived growth factor-A chain and basic fibroblast growth factor. The increase was observed within 4 h after angiotensin II stimulation. In this case, the addition of losartan at 4 h after angiotensin II stimulation hardly influenced the time course of the mRNA level of growth factors. Also, conditioned media of cells stimulated with angiotensin II did not influence DNA synthesis in the presence of CV11974. These results suggest that sustained receptor stimulation with angiotensin II is required for DNA synthesis in addition to the early intracellular signaling following phospholipase C activation in a manner independent of the induction of growth factors such as platelet-derived growth factor-AA and basic fibroblast growth factor.

Hinokitiol induces differentiation of teratocarcinoma F9 cells

Hinokitiol, a constituent of the wood of Chamaecyparis taiwanensis, was found to induce differentiation of teratocarcinoma F9 cells. When examined by the agar-overlay method, in which expression of plasminogen activator as a differentiation marker protein was detected, this compound exhibited a dose- and time-dependent induction. Induction of differentiation by hinokitiol occurred irreversibly and required its addition for more than 12h. Among its structure-related compounds tested, tropolone and two colchicine-related compounds exerted potent activities comparable to that of hinokitiol. These findings indicate that free tropolone structure in the molecules plays an essential role in inducing differentiation of F9 cells. Hinokitiol showed a strong inhibitory effect of DNA synthesis in very early stages of culture, suggesting that this effect may be responsible for triggering differentiation of F9 cells.

Induction of differentiation of embryonal carcinoma F9 cells by iron chelators

The effects of several chelators, including hinokitiol, on embryonal carcinoma F9 cell differentiation were assessed by assaying the production of plasminogen activator (PA) as a differentiation marker protein. Hinokitiol and tropolone which were potent differentiation inducers lost their activity following preincubation with Fe2+ and Fe3+ ions. Other metal ions had no or little effect on the hinokitiol-induced differentiation. Of several chelators examined, dithizone induced differentiation as effectively as did hinokitiol and tropolone. Dithizone-induced differentiation was also inhibited by preincubation with Fe3+ ions. It was concluded that some potent iron chelators could trigger the teratocarcinoma F9 cells to differentiate through the chelation with intracellular iron ions.

Mitochondrial DNA mutations in pancreatic biopsy specimens from IDDM patients

We investigated the contribution of mitochondrial DNA mutations to the pathogenesis of IDDM by analyzing mitochondrial DNA in pancreatic biopsy specimens and peripheral blood cells from 18 patients with newly-diagnosed IDDM. All patients presented with typical abrupt onset of diabetes and ketosis on initial examination. Point mutations at nucleotides 3243, 3271 and 8344 were assayed by polymerase chain reaction and restriction fragment length polymorphism analysis or by mismatch-primer analysis. A common large deletion from nucleotides 8483-13459 was analyzed by a primer shift method. All of these mutations are known to be pathogenic mutations. However, none of the mitochondrial DNA mutations were detected in any of 18 IDDM patients. Several types of mitochondrial DNA mutation have been identified in the peripheral blood cells in some patients with non-insulin-dependent diabetes mellitus as well as in some with IDDM, however, our results suggest that abrupt-onset IDDM does not correlate with any of the known mitochondrial DNA mutations.

Prophylaxis of genetically determined diabetes by diazoxide: a study in a rat model of naturally occurring obese diabetes

The study was carried out using a new rat model of naturally occurring obese, nonketotic diabetes, Otsuka Long-Evans Tokushima Fatty rat (Kawano et al., Diabetes 41: 1422-1428, 1992), which closely resembles obese noninsulin-dependent diabetes in human. At the age of 3.5 wk, body weight, glucose tolerance and plasma insulin level after glucose load were normal in Otsuka Long-Evans Tokushima Fatty rats, indicating the animals are at nonobese, prediabetic phase. At this age, however, glucose-stimulated insulin release by pancreatic islets in vitro was abnormally exaggerated whereas the islet insulin content and glucose metabolism by the islet cells were normal. Administration of diazoxide (0.2% in diet), an inhibitor of insulin secretion, to Otsuka Long-Evans Tokushima Fatty rats from the age of 4 to 12 wk completely prevented the development of obesity and insulin resistance, which was accompanied by marked improvement of glucose tolerance and disappearance of exaggerated B cell response to glucose in vitro. This is the first report of successful pharmacological prevention of genetically determined obese diabetes.

Studies on the activation mechanisms of guanylyl cyclase by serotonin, probably through a novel subtype of serotonin receptor (5-HTGC)

Characterization of the serotonin-induced increase in guanosine 3',5'-cyclic monophosphate (cyclic GMP) was investigated and compared with that induced by atrial natriuretic peptide (ANP) in NG108-15 cells. The cyclic GMP formed by serotonin or ANP was transported in a similar manner to the extracellular medium, although the cyclic GMP formed by bradykinin was not. Serotonin and ANP raised cyclic GMP additively. Serotonin-induced cyclic GMP formation was completely inhibited by pretreatment with 100 nM 12-o-tetradecanoylphorbol 13-acetate (TPA), although that induced by ANP was only partially inhibited and the effects were blocked by pretreatment with staurosporin. In membrane preparations, ANP stimulated cyclic GMP formation in the presence of ATP, but serotonin did not. Serotonin-stimulated cyclic GMP formation was found to occur in neuroblastoma N18TG-2, but not in glioma C6Bu-1. These results suggest that a novel subtype of serotonin receptors (5-HTGC) which stimulates membrane-bound guanylyl cyclase, different from that stimulated by natriuretic peptide, may exist especially in neurons.

Enhancement of gamma-actin protein during liver regeneration: its accumulation in a region adjacent to the hepatocyte plasma membrane

We identified a protein with a molecular weight of about 44 kDa in an extract of rat regenerating liver. This protein was undetectable in normal, sham-operated, and completely regenerated liver. We also purified this 44-kDa protein from an extract of rat liver remnant after partial hepatectomy. The partial amino acid sequences of the purified protein were identical to those of gamma-actin in non-muscle cells. In addition, anti-pan actin antibody recognized the purified 44-kDa protein, whereas anti-muscle actin and anti-beta-actin antibodies did not. Thus, we concluded that the 44-kDa protein was non-muscle gamma-actin. An immunohistochemical study revealed that the non-muscle gamma-actin accumulated next to the plasma membrane of liver parenchymal cells during regeneration. Moreover, the gamma-actin level was augmented in primary cultured rat hepatocytes prior to DNA synthesis. Intracellular gamma-actin in cultured hepatocytes was distributed across the entire basal plane after stimulation with hepatocyte mitogens. This change in the distribution of gamma-actin correlated with the cell spreading that occurred during the G1/S phase transition. These findings indicated that gamma-actin plays specific roles in the growth of liver parenchymal cells during liver regeneration.

Inhibitory effects of medroxyprogesterone acetate on mouse endometrial carcinogenesis

The present study was undertaken to examine the effects of cyclic administration of low-dose progestogen on endometrial carcinogenesis in mice. A total of 115 female ICR mice, 10 weeks of age, were divided into four experimental and control groups. Mice in groups 1-3 received laparotomy and were injected with N-methyl-N-nitrosourea (MNU) solution at a dose of 1 mg/100 g body weight to the left uterine tube and with normal saline to the right uterine tube. From one week after the MNU exposure, groups 1 and 2 were given 5 ppm 17 beta-estradiol (E2)-containing diet throughout the experiment. Mice in group 1 received 5 s.c. injections of medroxyprogesterone acetate (MPA) (2 mg/mouse) at intervals of 4 weeks from week 7. Group 3 was treated with MNU/normal saline alone. Group 4 consisted of mice treated with MPA alone. At the termination of the experiment (week 30), all animals were killed and autopsied for pathological examinations. It was found that adenocarcinomas and preneoplastic lesions developed in the bilateral uterine corpora in mice of groups 1-3. MPA treatment significantly decreased the weight of the uterine corpus (P < 0.05) and the incidences of endometrial adenocarcinoma and atypical or adenomatous (P < 0.001) but not cystic glandular hyperplasias in the MNU/E2-treated groups. Additionally, MPA treatment tended to decrease the proliferating cell nuclear antigen-labeling index in endometrial glandular cells. These data indicate that MPA, even at low dose, has an inhibitory effect on mouse endometrial carcinogenesis induced by MNU and E2.

Transient expression of FGF receptor-4 mRNA in the rat cerebellum during postnatal development

The fibroblast growth factor (FGF) receptor-4 mRNA in the adult rat brain is expressed preferentially in the medial habenular nucleus. In this paper, we examined the expression of FGFR-4 mRNA in the brain during postnatal development. Interestingly, in addition to the persistent expression of FGFR-4 mRNA in the medial habenular nucleus, FGFR-4 mRNA was transiently expressed in the proliferative zone of the external granule layer of the developing cerebellum. The localization and transient expression of FGFR-4 mRNA in the developing cerebellum suggest that FGFR-4 mRNA was expressed by proliferative granule cells. The present findings indicate that FGFR-4 in the brain has an important role in the postnatal development of the cerebellar cortex.

Frontal intermittent rhythmic delta activity (FIRDA) in pituitary adenoma

We report a case of FIRDA in the EEG of a patient diagnosed as major depression with pituitary adenoma and hyponatremic encephalopathy. The pituitary adenoma appeared to be a major factor responsible for FIRDA in this case. Although other factors associated with this case, i.e., diffuse encephalopathy and administration of antipsychotic drugs, have been reported to be causative, FIRDA remained in the EEG after these other factors diminished. Although size of the pituitary adenoma that might be associated with FIRDA in the EEG recording was not identified in this study, FIRDA may be associated with a small pituitary adenoma less than 10 mm in diameter. We think a diligent search for additional pathology is recommended if FIRDA is seen in the EEG of an otherwise normal patient.

Rare occurrence of p53 and ras gene mutations in preneoplastic and neoplastic mouse endometrial lesions induced by N-methyl-N-nitrosourea and 17 beta-estradiol

To examine K-, H-, or N-ras and p53 gene mutations in mouse endometrial carcinogenesis induced by N-methyl-N-nitrosourea and 17 beta-estradiol, we performed polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) in 13 adenocarcinomas and 11 other preneoplastic lesions. A significant shifted band in exon 5 of p53 using PCR-SSCP was detected in one of 13 adenocarcinomas. Direct sequencing showed that the mutation was TCA-to-TGA (Ser-to-End) transition. These results suggest that ras gene mutations were not related to carcinogenesis and inactivation of p53 may occur with low frequency during the mouse endometrial carcinogenesis in this model.

[Clinical studies of spermatogenic damage in patients with testicular cancer]

We investigated the spermatogenic function of patients with testicular cancer, and the influences of anti-cancer chemotherapy on testicular function in these patients. Fifty-one patients with testicular cancer were selected for evaluation of their testicular function, including spermatogenesis and endocrinological function, before and after chemotherapy with anti-cancer agents. Before chemotherapy with anti-cancer agents, 22 of 49 patients (44.8%) had a sperm concentration of less than 20 x 10(6)/ml, and 8 patients (16.3%) showed azoospermia. The mean sperm concentration of the patients with testicular cancer was 29.0 x 10(6)/ml before therapeutic chemotherapy with anti-cancer agents, but within 3 months after chemotherapy, it decreased to 3.86 x 10(6)/ml (p < 0.01). Fifteen of 19 patients (73.7%) were revealed to have azoospermia. Damage to spermatogenesis became more severe with the number of chemotherapy treatment. No patients had a detectable sperm count at the completion of 3 or more courses of chemotherapy. But some patients who received 3 courses or more of chemotherapy showed recovered sperm counts after 2 or more years. Thus, a lack of sperm after chemotherapy for cancer did not necessarily indicate inability to recover spermatogenesis over 2 years after chemotherapy. Serum FSH levels of the patients were 5.62 +/- 3.43 mIU/ml before chemotherapy, and 19. 70 +/- 17.06 mIU/ml (p < 0.05) at the time of its completion. Serum FSH levels could reflect damage to spermatogenesis in these cases. Cases in which spermatogenesis did not recover may have higher serum FSH levels than those with recovery of spermatogenesis.

Localization of fibroblast growth factor-9 mRNA in the rat brain

We examined the localization of fibroblast growth factor-9 (FGF-9) mRNA in the rat brain by in situ hybridization. FGF-9 mRNA was moderately or weakly expressed in widespread regions including the olfactory bulb, caudate putamen, cerebral cortex, hippocampus, thalamus, hypothalamus, midbrain, brainstem and cerebellum. However, FGF-9 mRNA was also strongly expressed in several specific nuclei including the red nucleus and oculomotor nucleus in the midbrain, the vestibular nucleus and facial nucleus in the brainstem and the medial cerebellar nucleus, interposed cerebellar nucleus and lateral cerebellar nucleus in the cerebellum. The cellular localization of FGF-9 mRNA indicated that the mRNA in the rat brain was expressed preferentially in neurons, although FGF-9 was originally isolated from human glioma cells. The localization profile of FGF-9 mRNA is different from those of aFGF, bFGF and FGF-5 mRNAs reported previously. The present findings indicate that FGF-9 has a unique role in the brain.

No detectable cytomegalovirus and Epstein-Barr virus genomes in the pancreas of recent-onset IDDM patients

Viral infection is assumed to trigger or exacerbate autoimmune responses against pancreatic beta cells leading to the development of insulin-dependent diabetes mellitus (IDDM). We therefore examined by polymerase chain reaction the presence of two candidate viruses, cytomegalovirus and Epstein-Barr virus, in IDDM pancreases. Pancreas tissues were obtained by biopsy under laparoscopy from 16 recent-onset IDDM patients: age 17-53 years; disease duration 0-7 months; six had flu-like symptoms before onset. Frozen sections were made and subjected to DNA amplification. DNA samples were prepared from the frozen sections and polymerase chain reaction was performed using primers specific to cytomegalovirus, Epstein-Barr virus and control gene for HLA-DP. Cytomegalovirus- and Epstein-Barr virus-infected cells were used for positive control. Southern blot analysis could detect cytomegalovirus DNA from as few as 2 x 10(-1) cytomegalovirus-infected cells and Epstein-Barr virus DNA from two Epstein-Barr virus-infected cells. This highly sensitive analysis, however, could not detect cytomegalovirus or Epstein-Barr virus genomes in pancreases of recent-onset IDDM. A single copy human gene (HLA-DP) was amplified from all IDDM pancreases indicating that DNA amplification was performed without inhibition. We conclude that cytomegalovirus or Epstein-Barr virus genomes are unlikely to exist in pancreas biopsy specimens of recent-onset IDDM patients.