Primary hypomagnesemia caused by isolated magnesium malabsorption: atypical case in adult

Isolated magnesium malabsorption is a rare disorder, which bas been described in no more than 30 patients worldwide. Patients with this disorder typically present with convulsion and diarrhea in early infancy. Hypomagnesemia and hypocalcemia were found in a 35-year-old man with muscle cramps, who bad been diagnosed as primary hypoparathyroidism. Oral magnesium therapy corrected the low serum calcium, magnesium and parathyroid hormone levels. We report an atypical case of isolated magnesium malabsorption in an adult.

p73 at chromosome 1p36.3 is lost in advanced stage neuroblastoma but its mutation is infrequent

p73, a novel p53 family member, is a recently identified candidate neuroblastoma (NBL) suppressor gene mapped at chromosome 1p36.33 and was found to inhibit growth and induce apoptosis in cell lines. To test the hypothesis that p73 is a NBL suppressor gene, we analysed the p73 gene in primary human NBLs. Loss of heterozygosity (LOH) for p73 was observed in 19% (28/151) of informative cases which included 92 mass-screening (MS) tumors. The high frequency of p73 LOH was significantly associated with sporadic NBLs (9% vs 34%, P<0.001), N-myc amplification (10% vs 71%, P<0.001), and advanced stage (14% vs 28%, P<0.05). Both p73alpha and p73beta transcripts were detectable in only 46 of 134 (34%) NBLs at low levels by RT-PCR methods, while they were easily detectable in most breast cancers and colorectal cancers under the same conditions. They found no correlation between p73 LOH and its expression levels (P>0.1). We found two mutations out of 140 NBLs, one somatic and one germline, which result in amino acid substitutions in the C-terminal region of p73 which may affect transactivation functions, though, in the same tumor samples, no mutation of the p53 gene was observed as reported previously. These results suggest that allelic loss of the p73 gene may be a later event in NBL tumorigenesis. However, p73 is infrequently mutated in primary NBLs and may hardly function as a tumor suppressor in a classic Knudson's manner.

[A case of psoriatic arthritis associated with ankylosing spondylitis treated with bilateral total hip arthroplasty]

We report a case of a 40-year-old male with psoriatic arthritis associated with ankylosing spondylitis. At the age of 34, the patient suffered pain in his hips, knees, ankles, neck and low back 3 years after the onset of psoriasis vulgaris. The hip pain gradually became severe despite the medical treatment and physical therapy. On admission, the skin lesion of diffuse erythematous plaques with scales was observed on the trunk and extremities. Motion of the spine was markedly limited. We also noted limitation of motion in the bilateral hips and remarkable gait disturbance. In laboratory findings, rheumatoid factor and HLA-B 27 antigen were negative. Radiographs of the cervical spine showed typical bamboo spine as seen in ankylosing spondylitis. Obliteration of the sacroiliac joints and joint space narrowing in the hips with reactive sclerosis were revealed on the pelvic film. Bilateral cementless total hip arthroplasty with adductor tenotomy resulted in complete pain relief and a marked improvement in gait function 18 months after surgery. The appropriate reconstructive surgery was extremely helpful to increase daily activities of the patient in this case.

Characterization of an ascidian maternal T-box gene, As-mT

The T-box genes encode a novel family of transcriptional factors that seem to play crucial roles in various processes of animal development, in particular, mesoderm formation of chordate embryos. The ascidian egg has been regarded as a typical mosaic egg, in which several types of embryonic cells are specified autonomously dependent on prelocalized maternal factors or determinants. In the present study, we investigated a possible role of a maternal T-box gene (As-mT) of the ascidian Halocynthia roretzi. A cDNA clone we obtained predicted As-mT protein of 891 amino acids with a distinct T-domain, which was divergent from those of other T-box genes. Expression of As-mT was exclusively maternal. Although the transcript became barely detectable by the gastrula stage, no zygotic expression was evident during embryogenesis. The maternal transcript was distributed rather evenly within eggs and early embryos without any special localization. Injection of synthetic As-mT mRNA into fertilized eggs induced retardation of embryogenesis. Although cleavage occurred normally, the initiation of gastrulation was delayed, and delay in the morphogenesis resulted in dumpy larvae. Expression of a muscle-specific actin gene, a notochord-specific Brachyury gene, and an epidermis-specific gene was not detected at the early gastrula stage, all of the three genes being expressed in normal embryos at that stage. However, the expression of these genes as well as a mesenchyme-specific gene and histochemical activity of endoderm-specific alkaline phosphatase were evident by the mid-tailbud stage.

Mutational analysis of the p73 gene localized at chromosome 1p36.3 in colorectal carcinomas

Genetic alteration of p53, which monitors DNA damage and operates cellular checkpoints, is a major factor in the development of human colorectal carcinoma (CRC). Recently, p73, a novel family member of p53, has been identified and found, like p53, to activate p21Waf1/Cip1 and to induce apoptosis. The p73 gene was mapped at chromosome 1p36.3 which is a region frequently deleted in CRCs and other cancers including neuroblastoma. To assess whether or not p73 is a tumor suppressor gene of CRC, we performed mutational analysis of p73 in 82 colorectal tumor tissues paired with constitutional DNA. Using a microsatellite marker for p73, the loss of heterozygosity (LOH) study was performed and allelic loss of p73 was found in 17% of the CRCs. RT-PCR single strand conformation polymorphism analysis showed no mutation except three polymorphisms in the p73 coding region. In addition, p73 was expressed at higher levels in the CRC tissues than in the normal mucosa or neuroblastoma tissues, though the transcripts were detectable only by the RT-PCR method. Our results suggest that, in CRCs, p73 may not play a role as a tumor suppressor, at least not in a classic Knudson manner.

Lyme disease Borrelia species in northeastern China resemble those isolated from far eastern Russia and Japan

Fifty-nine Borrelia burgdorferi sensu lato culture isolates collected from northeastern China were characterized by 5S-23S rRNA intergenic spacer restriction fragment length polymorphism (RFLP) analysis and reactivity with monoclonal antibodies (MAbs). Among 59 culture isolates, 30 (50.8%) were Borrelia garinii and 17 (28.8%) were Borrelia afzelii, 2 were mixtures composed of B. garinii with RFLP pattern B and B. garinii with pattern C, and 9 were mixtures composed of B. garinii and B. afzelii. One isolate, ChY13p, produced a unique pattern and was identified as B. garinii based on analyses of 16S rRNA gene sequence, flagellin PCR-RFLP typing, and MAb reactivities. No Borrelia burgdorferi sensu stricto or Borrelia japonica isolates were detected. The results indicate that Lyme disease Borrelia species in northeastern China resemble those of Borrelia isolates from far eastern Russia and Japan.

Lyme disease spirochetes in ticks from northeastern China

During May 1996, field surveys on Lyme disease spirochetes were conducted in Beijing, Shenyang, Fushun, and Inner Mongolia in northeastern China. The ticks collected consisted of 3 genera and 12 species. Of these, Ixodes persulcatus was dominant in sun-exposed vegetation in forests in Inner Mongolia; 57 Borrelia strains (55/123 unfed adults and 2/5 immature stages fed on a rodent) were obtained from this tick by BSK culture. Additionally, 2/2 Apodemus peninsulae were positive. Ixodes nipponensis, Ixodes pavlovskyi, Haemaphysalis douglasi, and Haemaphysalis megaspinosa, newly recorded in China, and other Haemaphysalis spp. were all negative for Borrelia. Based on a polymerase chain reaction restriction fragment length polymorphism analysis of the 45 strains successfully subcultured, these were classified as 29 Borrelia garinii and 16 Borrelia afelii. These strains seemed to be more closely related to Japanese strains in genetic features than to those from Europe. The result of sodium dodecyl sulfate-polyacrylamide gel electrophoresis suggested more diversity in both genospecies, but Borrelia burgdorferi sensu stricto was not found.

Cancer prevention by organosulfur compounds from garlic and onion

Environmental compounds are known to be involved in both the generation and prevention of many human cancers. It is important to discover naturally occurring or synthetic compounds which can block the process of carcinogenesis. We have focused attention on several organosulfur compounds (OSCs) in garlic and onion, and analyzed their potential for chemoprevention in the post-initiation stage in a liver medium-term bioassay (Ito test) and a multi-organ carcinogenesis bioassay. In the ITO test, rats were given diethylnitrosamine (DEN), 200 mg/kg b.w., i.p.; starting 2 weeks later they were treated with test chemicals for 6 weeks and then killed. All rats were subjected to 2/3 hepatectomy 1 week after the start of test chemical treatment. Inhibitory effects of a number of compounds could be identified in terms of reduced numbers and areas of liver glutathione S-transferase placental (GST-P) positive foci. In the multi-organ carcinogenesis bioassay, rats were given DEN, N-methyl-N-nitrosourea, N-butyl-N-(4-hydroxybutyl)nitrosamine, N,N'-dimethylhydrazine, and dihydroxy-dipropylnitrosamine during the first 4 weeks, followed by test chemicals for 24 weeks. Various organs were examined. As a result, oil-soluble OSCs such as methyl propyl disulfide and propylene sulfide demonstrated inhibitory effects on the development of GST-P positive foci. Moreover, water-soluble OSCs such as S-methylcysteine and cysteine similarly decreased GST-P focus formation. In contrast, OSCs such as diallyl sulfide, diallyl trisulfide, and allyl methyl trisulfide enhanced formation of such altered hepatocellular foci. Inhibitory potential for colon and renal carcinogenesis was observed in rats treated with diallyl disulfide. Thus, the results indicate that some OSCs exert chemopreventive effects on chemical carcinogenesis. It must, however, be borne in mind that they may also demonstrate promotion potential, depending on the organ examined.

Molecular cloning and functional characterization of a novel receptor-activated TRP Ca2+ channel from mouse brain

Characterization of mammalian homologues of Drosophila TRP proteins, which induce light-activated Ca2+ conductance in photoreceptors, has been an important clue to understand molecular mechanisms underlying receptor-activated Ca2+ influx in vertebrate cells. We have here isolated cDNA that encodes a novel TRP homologue, TRP5, predominantly expressed in the brain. Recombinant expression of the TRP5 cDNA in human embryonic kidney cells dramatically potentiated extracellular Ca2+-dependent rises of intracellular Ca2+ concentration ([Ca2+]i) evoked by ATP. These [Ca2+]i transients were inhibited by SK&F96365, a blocker of receptor-activated Ca2+ entry, and by La3+. Expression of the TRP5 cDNA, however, did not significantly affect [Ca2+]i transients induced by thapsigargin, an inhibitor of endoplasmic reticulum Ca2+-ATPases. ATP stimulation of TRP5-transfected cells pretreated with thapsigargin to deplete internal Ca2+ stores caused intact extracellular Ca2+-dependent [Ca2+]i transients, whereas ATP suppressed [Ca2+]i in thapsigargin-pretreated control cells. Furthermore, in ATP-stimulated, TRP5-expressing cells, there was no significant correlation between Ca2+ release from the internal Ca2+ store and influx of extracellular Ca2+. Whole-cell mode of patch-clamp recording from TRP5-expressing cells demonstrated that ATP application induced a large inward current in the presence of extracellular Ca2+. Omission of Ca2+ from intrapipette solution abolished the current in TRP5-expressing cells, whereas 10 nM intrapipette Ca2+ was sufficient to support TRP5 activity triggered by ATP receptor stimulation. Permeability ratios estimated from the zero-current potentials of this current were PCa:PNa:PCs = 14.3:1. 5:1. Our findings suggest that TRP5 directs the formation of a Ca2+-selective ion channel activated by receptor stimulation through a pathway that involves Ca2+ but not depletion of Ca2+ store in mammalian cells.

Expression and localization of ornithine decarboxylase in reversible papillomatosis induced by uracil in rat bladder

Direct mechanical irritation by uracil calculi formed following feeding of 3% uracil in the diet to male rats produces severe papillary hyperplasia (papillomatosis, which is reversible) of bladder epithelium. To evaluate the mechanism of the appearance of uracil-induced papillomatosis, we examined the changes of the enzyme activity and the localization of ornithine decarboxylase (ODC), as well as polyamine biosynthesis, and epithelial proliferation, that accompany the sequential bladder epithelial changes following administration and withdrawal of uracil. Moreover, expression of ODC mRNA was investigated using northern blotting and localization of ODC mRNA was demonstrated using in situ hybridization. ODC activity during uracil administration was maintained at a high level compared to that in normal epithelium, but sharply decreased after cessation of uracil treatment. The accumulation of ODC protein was observed in the proliferating bladder epithelium by immunohistochemical examination and western blotting analysis, and even after cessation of treatment, the protein binding to anti-ODC antibody remained mildly elevated. Sequential changes of proliferating cell nuclear antigen (PCNA)-positive cells in the epithelium during the development and disappearance of papillomatosis correlated with ODC activity. ODC mRNA was expressed strongly in the proliferating epithelium in rats treated with uracil and weakly in normal epithelium, in accordance with the location of ODC protein. Consequently, our data demonstrate that cell proliferation in the development of papillomatosis is closely associated with polyamine metabolism, and moreover suggest that ODC activity is up-regulated at a post-translational step.

Differential distribution of TRP Ca2+ channel isoforms in mouse brain

Mammalian homologues of the Drosophila TRP proteins, which are essential for light-activated, phosphatidyl-inositide (PI)-dependent Ca2+ conductance in Drosophila photoreceptors, were molecularly identified, to investigate receptor-activated Ca2+ influx in the mammalian nervous system. Two cloned mouse TRP homologues, TRP3 and TRP4, structurally related to the voltage-dependent Na+ channel, were expressed predominantly in the brain, where a sharp contrast in the distribution of the RNA transcripts for TRP isoforms was demonstrated by in situ hybridization analysis. TRP3 mRNA was concentrated in cerebellar Purkinje cells and sparsely localized in the cerebellar granule layer, pontine nuclei, and thalamus, whereas TRP4 mRNA was abundantly expressed in hippocampal CA1 pyramidal neurons, dentate gyrus granule cells, and cerebral cortical neurons, and in the septal nuclei and the mitral layer of olfactory bulb. The distinct spatial patterns of TRP isoforms implicate that neurons are highly heterogeneous in receptor-activated Ca2+ influx responsible for the second phase of PI-mediated rise in intracellular Ca2+.

Increased levels of macrophage colony-stimulating factor, gamma interferon, and tumor necrosis factor alpha in sera of patients with Orientia tsutsugamushi infection

Levels of macrophage colony-stimulating factor (nine of nine patients) and gamma interferon (six of nine patients) in serum were elevated above the range of normal in the acute phase of tsutsugamushi disease. Significant increases in levels of tumor necrosis factor alpha were observed during the convalescent phase in five patients, and they exceeded the levels observed during the acute phase. Hypercytokinemia appeared to be responsible for the emergence of the symptoms of tsutsugamushi disease.

[Thoracoscopic enucleation of esophageal leiomyoma]

We treated four cases of thoracoscopic enucleation of esophageal leiomyoma. All four cases were asymptomatic, but either barium swallow or esophagofiberscopic examination revealed esophageal submucosal tumor. The locations of the tumors were middle and lower in one case and middle in the other three cases. All patients were intubated with a double lumen endotracheal tube under general anesthesia. Two patients required thoracotomy due to the tumor surrounding the esophageal wall in one case and severe adhesion to the esophageal mucosa in the other. The mini-thoracotomy was used in three cases. In the other two cases, we used four and three trocars, respectively. The balloon catheter, which had been inserted into the esophageal lumen, was useful for removing the tumor. The tumor was pulled up using the traction suture and dissected from the mucosa and muscular layer. After enucleation of the leiomyoma, the split muscular layer was sutured. The postoperative course was uneventful. These two patients were discharged on the 12th and 15th postoperative days, respectively. We conclude that the thoracoscopic enucleation of the esophageal leiomyoma is useful for reduction of surgical stress and is a more feasible approach for the treatment of esophageal leiomyoma.

Localization of insulin receptor-related receptor in the rat kidney

Insulin receptor-related receptor (IRR), a member of the insulin receptor family, is most abundantly expressed in the kidney. However, its endogenous ligand and physiological roles are still unknown. To elucidate the physiological role of IRR, an orphan receptor, in the kidney, we examined the localization of IRR mRNA and its immunoreactivity in the rat kidney by in situ hybridization and immunohistochemistry, respectively. IRR mRNA was found to be exclusively localized in the cortical collecting duct. The localization of IRR immunoreactivity was consistent with that of IRR mRNA. Furthermore, IRR immunoreactivity was found to be localized on the basolateral plasma membrane of the epithelial cells that were a minor cell subpopulation (20 to 30%) of the duct. The present findings indicated that IRR in the kidney was exclusively localized on the basolateral plasma membrane of type B intercalated cells of the cortical collecting duct.

Carcinogenicity of methylurea or morpholine in combination with sodium nitrite in rat multi-organ carcinogenesis bioassay

For carcinogenic risk assessment of combinations of N-nitroso precursors in man, the effects of feeding methylurea (MU) or morpholine (Mor) plus sodium nitrite (NaNO2) were investigated using a multi-organ carcinogenesis model. In experiment 1, to initiate multiple organs, groups of 10 or 20 male F344 rats were treated with 6 carcinogens targeting different organs. Starting a week after completion of this initiation phase, animals were given 0.1% MU or 0.5% Mor in their food and/or 0.15% NaNO2 in their drinking water for 23 weeks. The induction of tumors and/or preneoplastic lesions in the forestomach and esophagus was significantly increased in the group receiving MU plus NaNO2. The numbers and areas of liver glutathione S-transferase placental form (GST-P)-positive foci were significantly elevated with MU or Mor plus NaNO2. Experiment 2 was conducted to assess formation of N-nitroso compounds in the stomach, and to detect DNA adduct generation in target organs by immunohistochemical staining. Groups of 5 or 14 animals were starved overnight, then given 0.4% MU or 2.0% Mor in the diet, or basal diet alone for 1 h. Then NaNO2 or distilled water was given intragastrically. The mean gastric N-methyl-N-nitrosourea yield in the MU plus NaNO2 group was 7700 micrograms at 2 h after combined administration. The mean N-nitrosomorpholine yield in the group given Mor plus NaNO2 was 6720 micrograms. Immunohistochemically, N7-methyldeoxyguanosine-positive nuclei were evident in the forestomach epithelium at 8 h after the combination treatment with MU plus NaNO2.

[Pulmonary actinomycosis resembling an anterior mediastinal tumor]

A 25-year-old, previously healthy man was referred to us because of fever, left-sided chest pain, and an abnormal mass shadow at the left pulmonary hilum on chest X-ray films. Laboratory tests and fiberoptic bronchoscopy revealed no abnormality. Thoracotomy was done because a mediastinal tumor was suspected. Surgery revealed that the left lingula was atelectatic and that the mass was in the left S4, not in the mediastinum. Pathological examination of tissue from the partially resected lung showed sulfur granules, and a diagnosis of pulmonary actinomycosis was made. At least 80 cases of pulmonary actinomycosis were reported in Japan between 1963 and 1995. Pulmonary actinomycosis is most common among men in the fifth and sixth decades of life, and almost all patients have oral disease. Pulmonary actinomycosis is often difficult to distinguish from lung cancer, because both appear as mass shadows on X-ray films, and almost all cases of pulmonary actinomycosis are diagnosed by thoracotomy.

Reversibility and apoptosis in rat urinary bladder papillomatosis induced by uracil

Apoptosis is a morphologically and biochemically distinct form of cell death which determines specific patterns of tissue size and shape and balances cell proliferation. In the present study, the sequence of cellular proliferative alterations in urinary bladder epithelium associated with uracil-induced reversible urinary calculi was investigated in male F344 rats. Group 1 consisted of 45 rats, 6 weeks old at commencement of the experiment, which were given a diet containing 3% uracil for 8 weeks and were then returned to basal diet until week 20. Five rats were killed at each of weeks 2, 4, 8, 9, 10, 11, 12, 14 and 20. Group 2 consisted of 15 rats which were given basal diet for 20 weeks. Five rats were killed at each of weeks 0, 8 and 20. Microscopic, reversible papillomatosis, which showed papillary projections of epithelial proliferation, was seen in the urinary bladder of all rats in group 1 through week 8. No epithelial lesions were apparent in any of rats in group 2. Anti-Le(y)(BM-1/JIMRO)-positive areas of the urinary bladder epithelia were immunohistochemically seen in all rats of group 1 at weeks 2-12. At week 9 the percentage of anti-Le(y)-positive areas reached a maximum. Nick-end labeling stained nuclei of cells in the urinary bladder epithelium were observed in all rats of group 1 at weeks 4-14. At week 10 the labeling index was at a maximum. Proliferating cell nuclear antigen (PCNA)- and cyclin D1-positive cells of the urinary bladder epithelium were observed in group 1 at weeks 2, 4 and 8, however, at week 9 there were no PCNA- and cyclin D1-positive cells. In urinary bladder papillomatosis the simultaneous existence of apoptotic cells and proliferating cells was shown by double staining with anti-Le(y) (BM-1/JIMRO) and for PCNA. At week 10 apoptosis, stained by BM-1 and nick-end labeling, occurred extensively in regressing urinary bladder papillomatosis. Agarose gel electrophoresis of DNA in regressing papillomatosis at week 9 showed DNA fragmentation. Thus, these results indicate that apoptosis occurs in the process of papilloma regression following withdrawal of uracil treatment.

A comparative review of the immunobiology of murine neuroblastoma and human neuroblastoma

BACKGROUND

The prognosis for children with neuroblastoma (NB) remains dismal, in part because of extent of disease at diagnosis as well as resistance of tumors to conventional therapies. However, human NB exhibits many favorable traits, including the capability to mature into a more benign form or to regress spontaneously. A murine model of disease that could permit eventual genetic manipulation, so that such beneficial traits could be identified or even augmented, would be most useful.

METHODS

This report details an analysis of the contemporary study of the tumor growth, metastases, immunogenicity, and immunotherapy of murine NB and compares it with known patterns of clinical NB.

RESULTS

Striking similarities exist in the local tumor growth and metastatic behaviors of murine and human NB, behaviors that in part may be related to a host-tumor immunologic response. The naturally low expression of class I antigen in NB, the ability to augment that expression with cytokines, and the phenotype of the cellular and humoral immune response to NB are strikingly similar in human and murine hosts. Comparable immunotherapeutic potential exists. There have been rare and sporadic observations of spontaneous regression of an existing murine NB, unlike the more predictable regression of Evans Stage IV-S clinical NB.

CONCLUSIONS

The many similar biologic, physiologic, and immunologic characteristics of human and murine NB make the murine model a valuable adjunctive aid in furthering our understanding of human disease.

S-methylcysteine and cysteine are inhibitors of induction of glutathione S-transferase placental form-positive foci during initiation and promotion phases of rat hepatocarcinogenesis

S-Methylcysteine (SMC) occurs in a variety of plants, including Allium sativum, Phaseolus vulgaris, and Cruciferae. In this study, we synthesized five organosulfur compounds (OSCs), SMC and four analogs, and examined their modifying effects on diethylnitrosamine-induced neoplasia of the liver in male F344 rats, using the medium-term bioassay system of Ito (Ito test) based on the two-step model of hepatocarcinogenesis. In addition, we investigated the modifying effects of SMC and cysteine on the initiation stage of rat hepatocarcinogenesis. Carcinogenic potential was scored by comparing the numbers and areas of induced glutathione S-transferase placental form (GST-P)-positive hepatocellular focl. All OSCs examined had a tendency to decrease the number of GST-P-positive foci when given in the promotion stage of the Ito test, and in particular SMC and cysteine exerted significant inhibitory effects. When given during the initiation stage, these two OSCs also significantly inhibited focus formation. Regarding the mechanism underlying the inhibitory effects of SMC and cysteine, measurement of ornithine decarboxylase in SMC- and cysteine-treated liver tissues after partial hepatectomy (PH) revealed a significantly reduced activity, and the proportion of hepatocytes positive for proliferating cell nuclear antigen was significantly decreased by SMC or cysteine administration. Moreover, examination of the expression of the early response proto-oncogenes, c-fos, c-jun, and c-myc, after PH demonstrated down-regulated induction of c-jun mRNA transcripts by SMC, sustained for an eight-hour period. Our results support the view that SMC and cysteine are chemopreventive agents for rat hepatocarcinogenesis and that their intake may be importance for cancer prevention.

Overexpression of cyclin D1 in rat esophageal carcinogenesis model

Overexpression of cyclin D1 in human esophageal carcinomas has been well documented. The aim of the present study was to assess the expression of cyclin D1 in different types of esophageal epithelial lesions induced by N-nitrosomethylbenzylamine (NMBA) in rats. A total of 30 rats received s.c.-injections, five times/week, of 1.0 mg/kg NMBA for a period of 5 weeks followed by the same dose once per week for another 10 weeks. An additional 15 rats were given saline and used as controls to provide normal epithelium. The tumor incidence was 100% at the termination point of 21 weeks. Seventeen rats (57%) showed nuclear staining for cyclin D1, with a great variation in the intensity, as demonstrated by using an immunohistochemical technique. The cyclin D1 positive indices were in the range of 0% to 60% of the individual cells. Negligible staining was observed for normal esophageal epithelium, with a minimal increase in hyperplastic and dysplastic lesions. A significant elevation of cyclin D1 levels was observed in tumors. However, no significant differences were found between papillomas and carcinomas. The immunohistochemical results were confirmed by western blotting analysis. Tumors, papillomas and carcinomas overexpressing cyclin D1 had elevated proliferating cell nuclear antigen (PCNA) indices (P < 0.05). The correlation coefficient of overexpressions of PCNA and cyclin D1 was r = 0.7 for papillomas, but only r=0.3 for carcinomas. The study thus provides strong evidence of relatively early overexpression of cyclin D1 during tumorigenesis in the present rat esophageal model. Cyclin D1 expression is not simply a direct consequence of increase cell proliferation.