EPO-producing gastric carcinoma in a hemodialysis patient

Idiopathic erythrocytosis in a patient on chronic hemodialysis

A 78-year-old man on hemodialysis presented to our hospital with erythrocytosis. He had started hemodialysis 4 years previously, with a hemoglobin level of 9.8 g/dL, and was administered erythropoiesis stimulating agents and ferrous sulfate. Two years previously, his hemoglobin level increased to 14.5 g/dL and the treatment for anemia was discontinued. He continued hemodialysis thrice weekly; however, the hemoglobin level had increased to 17.0 g/dL at the time of presenting to our hospital. His serum erythropoietin level was 31.4 mIU/mL (range, 3.7–31.5 mIU/mL), carboxyhemoglobin level was 0.6% (range, 0–1.5%), and oxygen saturation in ambient air was 95.4%. The JAK2 V617F mutation was not observed and other bone marrow abnormalities were not identified. The patient was diagnosed with bladder cancer and a transurethral resection was performed. Eight months after the treatment of bladder cancer, his hemoglobin level was 15.1 g/dL, and he was diagnosed with idiopathic erythrocytosis.

Thiazide-sensitive Na+-Cl- cotransporter: genetic polymorphisms and human diseases

The thiazide-sensitive Na(+)-Cl(-) cotransporter (TSC) is responsible for the major sodium chloride reabsorption pathway, which is located in the apical membrane of the epithelial cells of the distal convoluted tubule. TSC is involved in several physiological activities including transepithelial ion absorption and secretion, cell volume regulation, and setting intracellular Cl(-) concentration below or above its electrochemical potential equilibrium. In addition, TSC serves as the target of thiazide-type diuretics that are the first line of therapy for the treatment of hypertension in the clinic, and its mutants are also reported to be associated with the hereditary disease, Gitelman's syndrome. This review aims to summarize the publications with regard to the TSC by focusing on the association between TSC mutants and human hypertension as well as Gitelman's syndrome.

Erythropoietin-producing tubercle granuloma in a hemodialysis patient

Background

We describe a case of a fever of unknown etiology that was caused by a caseating tubercle granuloma which produced erythropoietin. To our knowledge, this is the first report of an erythropoietin- producing granuloma.

Case presentation

A 48-year-old Japanese man with a 5-year history of maintenance hemodialysis for diabetic nephropathy presented with an intermittent fever over a few months. During febrile periods he developed erythema nodosum on his legs. Computed tomography showed axillary lymph node enlargement and this was further corroborated by a gallium scan that revealed high gallium uptake in these nodes. A Mantoux test was positive and an interferongamma release assay for tuberculosis diagnosis was also positive. Lymph node tuberculosis was suspected and the patient underwent lymphadenectomy. Histological analysis of the lymph nodes revealed a caseating granuloma that showed positive results on an acid-fast bacteria stain and a Mycobacterium tuberculosis polymerase chain reaction test. After lymphadenectomy, however, the patient’s hemoglobin levels rapidly decreased from 144 to 105 g/L, and this was further compounded by a decrease in serum erythropoietin from 223 mIU/mL to 10.7 mIU/mL by postoperative day 21. We suspected the tubercle to be a source of the erythropoietin and this was further confirmed by in situ hybridization.

Conclusions

We report for the first time ectopic erythropoietin production by a tuberculous lymph node. Our observations are substantiated by a postoperative decline in his erythropoietin level and a clinical requirement for erythropoietin treatment.

Idiopathic erythrocytosis in dialysis patients: a case report and literature review

Anemia is a common complication in end-stage renal disease (ESRD) patients. On the other hand, idiopathic erythrocytosis is extremely rare, with only a few cases reported in the literature. We present a case of erythrocytosis that developed after initiating hemodialysis. A 68-year-old male with a history of ESRD secondary to diabetes presented with erythrocytosis that started a few months after initiating dialysis in the absence of having received erythropoietin-stimulating agents or iron supplements. His erythropoietin level was elevated, with a negative JAK2 mutation. Blood gases showed normal oxygen and CO(2), with slightly elevated carboxyhemoglobin. Tiny foci in both kidneys were noted, representing vascular calcifications or renolithiasis. There was no radiological evidence of neoplasms or cysts. After excluding secondary causes, a diagnosis of idiopathic erythrocytosis was made. The patient underwent intermittent phlebotomies during dialysis, and his hemoglobin went from 18.5 to 14 mg/dl. Erythrocytosis in ESRD patients is very rare. So far, there is no complete understanding of the underlying pathophysiology; however, there seem to be multiple possible reasons for an increased erythropoietin level. Phlebotomy is a successful and easy way to control erythrocytosis in such patients. Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, currently being used in posttransplant erythrocytosis, might also be considered.

Polycythemia due to obstructive sleep apnea in a patient on hemodialysis

Both anemia and sleep disordered breathing are common in patients with dialysis-dependent stage 5 chronic kidney disease. Erythrocytosis resulting from obstructive sleep apnea (OSA) is rare in the general population and has never been described in the hemodialysis population. We present a case of asymptomatic isolated erythrocytosis and elevated serum erythropoietin level in an otherwise well and previously erythropoietin-dependent chronic hemodialysis patient with chronic kidney disease secondary to ischemic nephropathy. There was no history or symptoms of cardio-pulmonary or hepatic diseases nor any relevant family history. Screening work-up for malignancies was negative. The clinical history was highly suggestive of OSA and severe OSA (respiratory disturbance index of 59) was confirmed by polysomnographic studies. Successful treatment of the OSA with continuous positive airway pressure resulted in permanent stabilization of the hemoglobin to levels below 13 g/dL without the need for repeated phlebotomies and in dramatic lowering of serum erythropoietin levels. To our knowledge, this is the first case of OSA mediated erythrocytosis in a dialysis patient documented in the literature.

Erythropoietin and erythropoiesis

Although the concept of a humoral regulator of erythropoiesis was introduced more than 100 years ago, its existence was first firmly established a little more than 50 years ago. This review briefly describes the historical development of information about erythropoietin. It then describes our current understanding of where erythropoietin is produced; the factors that regulate its rate of production; how erythropoietin acts at the cellular level to stimulate erythropoiesis; and its role in the regulation of the rate of erythropoiesis. Finally, it discusses the clinical uses of erythropoietin in the diagnosis and therapy of hematopoietic diseases.

Erythropoietin gene expression in renal carcinoma is considerably more frequent than paraneoplastic polycythemia

Signalling by erythropoietin (EPO) is increasingly recognised as a relevant mechanism in tumour biology, potentially leading to enhanced proliferation, angiogenesis and therapy resistance. Paraneoplastic polycythemia by cancerous overproduction of EPO is a rare event, but most frequently seen in patients with renal cell carcinoma (RCC). The majority of clear cell RCC displays a strong activation of the transcription factor regulating EPO, the Hypoxia-inducible Factor (HIF). Therefore, it is unclear why only a small minority of patients develop polycythemia. We studied 70 RCC for EPO gene and HIFalpha isoform expression. 34% of all RCC showed expression of EPO mRNA in RNase protection assays, which were almost exclusively of the clear cell type. Only 1 patient presented with polycythemia. In situ hybridisation revealed that expression of EPO was in the tumour cells. Expression of EPO mRNA was always associated with activation of HIF, which could involve HIF-1alpha and/or HIF-2alpha. The frequency of EPO gene expression in RCC is therefore much higher than the prevalence of polycythemia. Furthermore, activation of HIF appears necessary for EPO gene expression in RCC, but is clearly not the only determinant. Further to the reported expression of EPO receptors in tumour tissues, the finding of widespread expression of EPO in RCC supports the recent notion of an involvement of this system in paracrine or autocrine effects of tumour cells.

Insulin but Not Phlorizin Treatment Induces a Transient Increase in GLUT2 Gene Expression in the Kidney of Diabetic Rats

BACKGROUND/AIMS

Increases in the renal glucose transporter gene expression are involved in renal tubule-glomerular diseases. Here we investigate the GLUT2 gene expression changes in the kidney of diabetic rats, by using insulin or phlorizin treatment.

METHODS

Rats were rendered diabetic and studied 20 days later: 4-12 h after one single injection of insulin or phlorizin, and 1-6 days after insulin or phlorizin injection twice a day, comparing with diabetic rats injected with placebo. GLUT2 was investigated by Northern and Western analysis.

RESULTS

In 20-day diabetic rats, acute treatment with insulin lowered the plasma glucose and increased the GLUT2 mRNA ( approximately 100%, p < 0.001) without changes in the protein content, while phlorizin lowered the plasma glucose, but changed neither the GLUT2 mRNA nor the protein expression. Twenty-four hours of insulin treatment increased both GLUT2 mRNA ( approximately 100%, p < 0.001) and protein ( approximately 50%, p < 0.01), but no effects of phlorizin were observed. After 6 days, insulin and phlorizin similarly reduced glycemia, with opposite effects upon plasma insulin and urinary glucose, and both treatments decreased GLUT2 mRNA and protein (p < 0.05).

CONCLUSION

In kidney of diabetic rats, an initial and transient upregulation of GLUT2 was induced specifically by insulin only. The 6-day normalization of GLUT2, however, was induced by both insulin and phlorizin treatment, which seems to be related to the plasma glucose lowering.

A cross-sectional immunosurveillance study of anti-EPO antibody levels in CRF patients receiving epoetin alfa in 5 Ontario Renal Centers

BACKGROUND

Epoetin alfa (Eprex*; Johnson & Johnson, Manati, PR) has been used successfully to correct the anemia of chronic renal failure for more than 12 years. Anti-erythropoietin (anti-EPO) antibodies have been reported in a small number of patients, resulting in a blood disorder, pure red cell aplasia (PRCA). To evaluate the utility of a large-scale anti-EPO antibody screening program in patients with chronic kidney disease (CKD) administered epoetin alfa, a study involving 5 large renal centers in southern Ontario, Canada, was conducted.

METHODS

More than 1,500 hemodialysis, peritoneal dialysis, and predialysis patients were screened for the prevalence of anti-EPO antibodies by means of a radioimmunoprecipitation (RIP) assay. Serum samples were drawn and shipped to PPD Development (Richmond, VA) for the immunoprecipitation assay. Serum EPO levels also were measured. All samples that tested positive or borderline for antibodies were sent to MDS Pharma Services (Montreal, Canada) for the neutralization assay.

RESULTS

Of 1,531 samples tested, 1 patient tested low-positive and 3 borderline results were detected by means of RIP. PRCA previously was diagnosed in the patient with the low-positive antibody level; the patient was treated with cyclosporine and currently is being administered epoetin alfa with good response. The 3 patients with borderline antibody results manifested no clinical signs of PRCA. Neutralization assays performed on all 4 serum samples were negative for anti-EPO antibodies.

CONCLUSION

Results from this surveillance study show that the prevalence of antibody to EPO in patients with CKD administered epoetin alfa in 5 Canadian renal centers is low, and the value of a large-scale antibody screening program for PRCA cannot be justified.

Influence of Na2SeO3 and gastric endocrine cells on MNNG induced gastric carcinogenesis in rats

AIM: To investigate influence of Na₂SeO₃ and gastric endocrine cells on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) induced gastric carcinogenesis in rats and its mechanism.

METHODS: Weaning male Wistar rats were divided randomly into four groups: The normal control group, experiment control group, low selenium (2 mg/L) group and high selenium group (4 mg/L). The Wistar rat gastric cancer was induced by MNNG (20 mg/kg) gavage daily for 10 days. Na₂SeO₃ was given by piped drinking before one week of MNNG (20 mg/kg) gavage. The Wistar rats were killed at the 43th week. The surface characters of gastric mucosa were observed with nude eyes. Histopathologic changes were observed by HE stain and AB-PAS methods. Changes of gastric endocrine cells were detected by immunohistochemical S-P method. The immunohistochemical results were quantitatively analyzed by the image analyzer. Statistical analysis was taken by SPSS.

RESULTS: Dietary Na₂SeO₃ (2 mg/L, 4 mg/L) aggravated gastric erosion and hemorrhage and promoted intestinal metaplasia of gastric mucosa (45.5%, 66.7%, 92.9%; 92.9% vs 45.5%, P < 0.05). Leiomyoma formed in the process of induced rats gastric carcinoma. Dietary Na₂SeO₃ (2 mg/L, 4 mg/L) increased incidence rate of leiomyoma. The numeric density of area (N_A) of SP immunohistochemical positive cells was significantly increased in low selenium group than those of normal control group (9.909±5.665 vs 4.455±2.583, P < 0.05). Absorbance mean (Amean) of gastrin immunohistochemical positive cells was significantly decreased in experimental control group, low selenium than that of normal control group (0.187±0.033, 0.119±0.024 vs 0.306±0.011, P < 0.01), and low selenium group than experiment control group (0.119±0.024 vs 0.187±0.033, P < 0.01). N_A and Amean of somatostation cells (SOM) were not significantly different in each group.

CONCLUSION: These findings suggested that dietary Na₂SeO₃ by piped drinking might not decrease incidence of Wistar rat gastric caner induced by MNNG. The mechanism may be involved in that selenium promoted SP cells proliferation and decreased secretion of gastrin cells in gastric mucosa.