Age of menopause and impact of climacteric symptoms by geographical region

OBJECTIVE

To describe differences in the age of onset of menopause and in the prevalence of climacteric symptoms in different geographical areas.

DESIGN

Systematic review of published data on onset of menopause and symptoms in Europe, North America, Latin America and Asia.

METHODS

We identified publications by searching electronic databases, including MEDLINE (1966-October 2009) and EMBASE (1975-October 2009). Primary search criteria were age of menopause and climacteric symptoms. A sensitive analysis that excluded papers without full data was performed.

RESULTS

The median age at menopause in Europe ranges from 50.1 to 52.8 years, in North America from 50.5 to 51.4 years, in Latin America from 43.8 to 53 years, and in Asia from 42.1 to 49.5 years. The frequency of vasomotor symptoms varies widely depending on the geographical region, selection of criteria, and method of symptom identification. The prevalence of such symptoms ranges from 74% of women in Europe, 36-50% in North America, 45-69% in Latin America and 22-63% in Asia, as reported in different, large, epidemiological studies.

CONCLUSION

There are wide geographical differences in the prevalence of menopausal symptomatology and some differences in the age of onset of menopause. Both in Asia and Latin America, women of poorer socioeconomic status have significantly earlier onset of menopause. Within a geographical region, there are ethnic differences in menopause symptoms. Given differences in study methodologies, firm conclusions are not possible. However, regional differences in age at menopause and in climacteric symptoms are important to acknowledge and lay the foundation for an informed approach to the management of menopause and an understanding of its impact on women's health in the different regions of the world.

Both physiological and pharmacological levels of melatonin reduce DNA adduct formation induced by the carcinogen safrole

Hepatic DNA adduct formation induced by the chemical carcinogen, safrole, was suppressed by both endogenous pineal melatonin release and by the exogenous administration of melatonin to rats. DNA damage after administration of of melatonin to rats. DNA damage after administration of 100 mg/kg safrole (i.p.) was measured by the P1 enhanced 32P-postlabeling analysis method. The RAL (relative adduct labeling) x 10(7) of carcinogen modified DNA in the liver of untreated controls and in safrole treated animals killed during the day, at night, after pinealectomy and pinealectomy plus melatonin injection (0.15 mg/kg x 4 or a total of 0.6 mg/kg) was 0, 12.6 +/- 0.75, 10.9 +/- 0.72, 13.6 +/- 1.12 and 5.7 +/- 0.53 respectively. For the same groups of animals, circulating melatonin levels at the termination of the study were 31 +/- 3, 29 +/- 2, 276 +/- 31, 24 +/- 1 and 13,950 +/- 1016 pg/ml serum respectively. The higher the melatonin concentration in the serum the lower was DNA adduct formation in the rat liver. Thus, high nocturnal levels of melatonin were protective against safrole-induced DNA damage. These findings indicate that the functional pineal gland plays an important role in oncostatic actions of carcinogens such as safrole. At physiological levels, melatonin seemed to prevent especially the formation of what was referred to as the N1 DNA adduct. Melatonin's ability to suppress DNA adduct formation may relate to its inhibitory effect on a mixed function oxidase, cytochrome p-450, and on the recently identified hydroxyl radical scavenging capacity of the indole. The oncostatic action of melatonin is also suggested by its nuclear accumulation and DNA stabilization characteristics. At pharmacological levels melatonin is extremely potent in preventing DNA modification induced by the chemical carcinogen, safrole.

High physiological levels of melatonin in the bile of mammals

Bile is an important physiological bodily fluid which functions in the regulation of cholesterol metabolism, promotes the absorption of lipid and fat-soluble vitamins by the gut and serves in the excretion of toxic substances from the liver. Conversely, due to autooxidative processes bile is highly toxic to the hepatocyte and gastrointestinal epithelium. In this investigation, extremely high day time physiological levels of the endogenous antioxidant, melatonin, were measured in the bile of several mammals including rat, guinea pig, rabbit, pig, monkey and humans. Melatonin concentrations in the bile samples ranged from 2,000 to 11,000 pg/ml when measured by radioimmunoassay (RIA). These melatonin levels in bile are 2 to 3 orders of magnitude higher than those in day time serum. The presence of melatonin in bile was confirmed by HPLC with an electrochemical detector. This method, like the RIA, also documented very high levels of melatonin in bile. The presence of high levels of melatonin in bile may be essential to prevent oxidative damage to biliary and small intestinal epithelium induced by bile acids and oxidized cholesterol derivatives.

Pterygium: prevalence, demography and risk factors

Pterygium is not just a degenerative disease, but may be a proliferative disorder of the ocular surface. The etiology of pterygia has intrigued researchers for centuries. Several surveys have consistently shown that countries nearer the equator have higher rates of pterygia. A possible reason for this geographic variation is that (ultraviolet) UV B light may be a risk factor for the development of pterygia. UV B radiation may induce cellular changes in the medial limbus of the cornea. Several case-control and cross-sectional studies have attempted to accurately quantify UV light exposure and document its relationship with pterygia. Genetic attributes and other lifestyle behaviors may also contribute to the development of pterygia. However, further research efforts are needed to enable us to better understand the relative contribution of the different risk factors and how each risk factor may be linked to pterygium formation. In addition, the underlying mechanism of the effects of UV radiation needs to be further evaluated. By readdressing these unresolved issues in a newly proposed epidemiological study, new measures might be taken to reduce incidences and improve clinical managements of diseases, in addition to preventing UV exposure by eliminating other contributory factors. Meanwhile, preventive measures such as protection of the eyes by the wearing of sunglasses with UV B protective lenses and brimmed hats outdoors are recommended.

Epithelial-mesenchymal transition (EMT) and activated extracellular signal-regulated kinase (p-Erk) in surgically resected pancreatic cancer

BACKGROUND

EMT or transformation to the mesenchymal phenotype plays an important role in tumor invasion and metastasis. In vitro data suggest that mesenchymal transformation may correlate with the activation of PI3 kinase and Ras/Erk pathways. We investigated the expression of EMT markers (low E-cadherin, high fibronectin, and vimentin) and their association with p-Erk in resected pancreatic cancer.

METHODS

Clinical data/surgical specimens from 34 consecutive pancreatic cancer patients (pts) who underwent pancreatectomy were included. Immunohistochemical staining was performed on formalin-fixed paraffin-embedded tissues using monoclonal antibodies against vimentin, fibronectin, E-cadherin, and p-Erk. The results were correlated with clinicopathological parameters and survival. Survival analysis (log-rank test, Cox proportional hazard model), categorical data analysis (Pearson's chi-square, Fisher's exact test) and Kendall's tau were performed at a significance level of 0.05.

RESULTS

The patient population was formed from 13 males and 21 females, with a median age of 66 years (range 38-84 years); American Joint Committee on Cancer (AJCC) stage 1 (n = 2), 2 (n = 27), 3 (n = 5); histological grade 1 (n = 4), 2 (n = 13), 3 (n = 16), 4 (n = 1). Median survival was 15 months (95% CI: 11-24 months). Fibronectin overexpression correlated with the presence of vimentin (p = 0.0048) and activated Erk (p = 0.0264). There was a borderline association of fibronectin with worsening grade (p = 0.06). A negative association between vimentin and E-cadherin was noted (p = 0.0024). Increased fibronectin or vimentin and decreased E-cadherin correlated with poor survival.

CONCLUSION

EMT is associated with poor survival in surgically resected pancreatic adenocarcinoma. A correlation between activated Erk and fibronectin was identified that may open avenues for targeted therapy for this subgroup.

Augmentation of indices of oxidative damage in life-long melatonin-deficient rats

The chief pineal secretory product, melatonin, is an efficient free radical scavenger and antioxidant. The current study tested whether the life-long reduction of endogenous melatonin levels due to pinealectomy would influence the accumulation of oxidatively damaged products as the animals aged. Rats were either pinealectomized or sham operated when they were 2-months-old. At 25 months of age these animals were killed along with 2-month-old controls. Aging in the pineal-intact animals was associated with increased levels of lipid peroxidation products (malondialdehyde and 4-hydroxyalkenals in the lung, kidney and skin), rises in an oxidatively damaged DNA product (8-hydroxy-deoxyguanosine in liver, kidney and pancreas), and in the levels of protein carbonyls (in the liver). Likewise, advanced age was associated with a significant decrease in membrane fluidity (increased membrane rigidity) of hepatic microsomes in pineal-intact rats. For all of these parameters and in a number of organs, pinealectomy caused further increases in the indices of oxidative damage. Consistent with previous suggestions, the implications of these findings is that aging is associated with the augmented accumulation of oxidatively damaged macromolecules and that these increases are exaggerated when a relative melatonin deficiency is induced by pinealectomy. The findings are consistent with the idea that the accelerated accumulation of oxidatively damaged products after pinealectomy was due to reduction in melatonin since it functions as a free radical scavenger and antioxidant. On the other hand, other pineal secretory products that were reduced as a consequence of pineal removal may have also been responsible for some of the observed changes.

Typing and subtyping of influenza viruses in clinical samples by PCR

Type A and B influenza viruses can cause a wide spectrum of illness, and these viruses are responsible for considerable mortality and morbidity. Rapid typing of isolates is desirable when amantadine treatment or prophylaxis of contacts of type A influenza virus carriers is considered, but the available rapid techniques lack sensitivity and standard diagnostic methods require expansion of virus in tissue culture or embryonated hens' eggs. We developed a series of oligonucleotide primers able to detect, type, and subtype type A influenza viruses in a single reverse transcription-PCR. RNA was isolated from clinical specimens, and cDNA was generated with random primers. PCR was carried out with a mixture of primers specific for influenza viruses of types B, A/H1 and A/H3, and subtyping of the neuraminidase was carried out on the same cDNA template under identical conditions. Amplified products were detected by ethidium bromide staining of amplified products after agarose gel electrophoresis. When it was used to test 98 clinical specimens, this method was comparable to standard culture techniques in the detection, typing, and subtyping of influenza viruses.

Geographic distribution, virologic and clinical characteristics of hepatitis B virus genotypes in China

The significance of hepatitis B virus (HBV) genotypes for the heterogeneity of chronic HBV infection and severity of liver disease is not well understood. The aim of this study was to determine the distribution and virologic characteristics of HBV genotypes in China and possible association with the diversity of liver disease. The study includes 1096 chronic HBV carriers from nine provinces in China. We collected clinical and laboratory data and analysed the HBV strains in sera by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and nucleotide sequencing techniques. The most common HBV genotypes were B (41%) and C (53%), while genotypes A and D were also found. A North-South divide was identified in genotype B and C distribution - genotype C was predominant in northern China, while genotype B was more prevalent in southern provinces. Patients with genotype B were younger than those with genotype C, and had a lower prevalence of HBeAg - 65%vs 72%, respectively (P = 0.03). However, the severity of liver disease did not differ significantly between patients infected with genotype B or C - neither when comparing liver function tests (1024 patients), nor hepatic inflammation and fibrosis (264 patients). Amongst 47 patients with genotype D (by PCR-RFLP), 37 (79%) were infected with a new subtype (designated Dc), having a recombination fragment from genotype C precore/core region. This is the first large-scale HBV genotype study from China and convincing documentation of the North-to-South gradient of genotypes C vs B in this country. HBV DNA recombination over the surface and precore/core genes increases the diversity of HBV strains and may have diagnostic and clinical implications.

Hepatitis C in asymptomatic blood donors

Among 248 asymptomatic blood donors positive for antibody to hepatitis C virus (anti-HCV) enrolled in a long-term prospective study, 86% had chronic HCV infection and 14% appeared to have recovered as assessed by serial determinations of serum alanine aminotransferase (ALT) levels and HCV RNA by polymerase chain reaction. Established parenteral risk factors for HCV transmission were identified in 75% of donors. In addition, there was a strong independent association between HCV positivity and cocaine snorting, suggesting that shared snorting devices may be a covert route of parenteral transmission. Ear piercing in males was also significantly associated with transmission. There was no evidence for sexual spread. Although the majority of HCV carriers had both biochemical and histological evidence of chronic viral hepatitis, the extent of liver injury was generally mild. Among a larger population of 280 HCV RNA-positive donors, 17% had repeatedly normal ALT levels, 45% had levels that did not exceed twice, and only 22% had levels that exceeded five times the upper limit of the normal range. Among 81 patients who underwent liver biopsy, only 13% had evidence of severe hepatitis (8%) or cirrhosis (5%), despite a duration of infection that generally exceeded 15 years. No severe histological lesions were observed in blood donors with chronic HCV infection who had repeatedly normal ALT levels. In both donors and blood recipients, the frequency of severe morbidity or mortality related to HCV infection was less than 10% during the first two decades of infection. Further long-term studies are required to see if the progression to severe outcomes continues to accrue at this slow pace or whether it accelerates during subsequent decades.

Meta-analysis: underutilisation and disparities of treatment among patients with hepatocellular carcinoma in the United States

BACKGROUND

Despite wide availability of treatment options for hepatocellular carcinoma (HCC), several studies have suggested underutilisation in clinical practice.

AIMS

To quantify utilisation rates for HCC treatment among patients with HCC in the United States, and to summarise patterns of association between utilisation rates and patient socio-demographic characteristics.

METHODS

We performed a systematic literature review using the Medline database from January 1989 to March 2013. Two investigators independently extracted data on patient populations, study methods and results using standardised forms. Pooled treatment rates for any treatment and curative treatment, with 95% confidence intervals, were calculated. Prespecified subgroup analysis was performed to identify patient-level correlates of treatment utilisation.

RESULTS

We identified 24 studies that met inclusion criteria. The pooled rates of any treatment and curative treatment were 52.8% (95% CI 52.2-53.4%) and 21.8% (95% CI 21.4-22.1%) respectively. Among patients diagnosed at an early stage, the pooled curative treatment rate was 59.0% (95% CI 58.1-59.9%). Elderly, non-Caucasians and patients of low socioeconomic status had lower treatment rates than their counterparts.

CONCLUSIONS

Rates of HCC treatment in the United States, including curative treatment rates among patients detected at an early stage, are disappointingly low. Future efforts should focus on identifying appropriate intervention targets to increase treatment rates and reduce socio-demographic disparities.

Dietary palmitic and oleic acids exert similar effects on serum cholesterol and lipoprotein profiles in normocholesterolemic men and women

To compare the effects of dietary palmitic acid (16:0) vs oleic acid (18:1) on serum lipids, lipoproteins, and plasma eicosanoids, 33 normocholesterolemic subjects (20 males, 13 females; ages 22-41 years) were challenged with a coconut oil-rich diet for 4 weeks. Subsequently they were assigned to either a palm olein-rich or olive oil-rich diet followed by a dietary crossover during two consecutive 6-week periods. Each test oil served as the sole cooking oil and contributed 23% of dietary energy or two-thirds of the total daily fat intake. Dietary myristic acid (14:0) and lauric acid (12:0) from coconut oil significantly raised all the serum lipid and lipoprotein parameters measured. Subsequent one-to-one exchange of 7% energy between 16:0 (palm olein diet) and 18:1 (olive oil diet) resulted in identical serum total cholesterol (192, 193 mg/dl), low-density lipoprotein cholesterol (LDL-C) (130, 131 mg/dl), high-density lipoprotein cholesterol (HDL-C) (41, 42 mg/dl), and triglyceride (TG) (108, 106 mg/dl) concentrations. Effects attributed to gender included higher HDL in females and higher TG in males associated with the tendency for higher LDL and LDL/HDL ratios in men. However, both sexes were equally responsive to changes in dietary fat saturation. The results indicate that in healthy, normocholesterolemic humans, dietary 16:0 can be exchanged for 18:1 within the range of these fatty acids normally present in typical diets without affecting the serum lipoprotein cholesterol concentration or distribution. In addition, replacement of 12:0 + 14:0 by 16:0 + 18:1, but especially 16:0 or some component of palm olein, appeared to have a beneficial impact on an important index of thrombogenesis, i.e., the thromboxane/prostacyclin ratio in plasma.

Vascular endothelial growth factor is elevated in ocular fluids of eyes harbouring uveal melanoma: identification of a potential therapeutic window

BACKGROUND

Improved local treatment of uveal melanoma makes it possible for many patients to retain the affected eye, but a proportion will develop secondary complications such as neovascularisation of the iris (NVI) and require enucleation. Although vascular endothelial growth factor A (VEGF-A) is known to correlate with NVI and can cause NVI in experimental models, this pro-angiogenic cytokine is consistently reported to be absent in uveal melanoma. Novel anti-VEGF therapies are now in clinical trial, and the authors therefore wished to determine whether VEGF-A was indeed elevated in melanoma bearing eyes.

METHODS

VEGF-A concentrations were measured in aqueous and vitreous from 19 and 30 enucleated eyes respectively.

RESULTS

Elevated VEGF-A concentrations (up to 21.6 ng/ml) were found in melanoma bearing eyes compared with samples from patients undergoing routine cataract extraction (all had values below 0.96 ng/ml). Immunohistochemistry showed VEGF-A protein in the iris and/or ciliary body of 54% and basic fibroblast growth factor (bFGF) in 82% of the eyes examined. VEGF was found to a limited extent and at very low levels in only 9% of these tumours. Aqueous or vitreous VEGF levels showed no apparent correlation with retinal detachment, tumour size, vascularity, or immunohistochemistry. Though limited in number, the highest VEGF levels correlated with previous radiation therapy, and with the presence neovascularisation of the iris or optic nerve head. bFGF was not significantly elevated in ocular fluids: it is known to be a pro-angiogenic agent and was detected in the majority of primary uveal melanomas.

CONCLUSION

Based on this study, though the source of VEGF within eyes harbouring uveal melanoma is not clear, these data suggest that anti-VEGF therapy might prove useful in the management of some patients with NVI secondary to uveal melanoma.

Proteomic Analysis of Human Tears: Defensin Expression after Ocular Surface Surgery

Human tear protein profiles were monitored by surface enhanced laser desorption/ionization-time-of-flight mass spectrometry ProteinChip technology (SELDI-TOF ProteinChip) and liquid chromatography-mass spectrometry (LC-MS). Tears were collected from 21 patients scheduled for surgery to remove an ocular surface neoplasm prior to surgery (day 0) and on days 1, 3, and 30 postoperatively. Using this proteomic approach, we verified that three human alpha-defensins (HNP-1, HNP-2, and HNP-3) were significantly up-regulated in their expression after surgery and that their levels decreased to approximately normal by day 30 by which time healing was complete. Further confirmation of the identity of the alpha-defensins in human tears was made by LC purification, trypsin digestion, and ESI-MS/MS analysis of their tryptic digests. The concentrations of HNP-1 and HNP-2 were determined and shown to be markedly increased after ocular surface surgery. The results of the study suggest that human alpha-defensins HNP-1, HNP-2, and HNP-3 are up-regulated after surgery, and may in addition to their antimicrobial properties have an important role in wound healing.

Is downregulation of MHC class I antigen expression in human non-small cell lung cancer associated with prolonged survival?

PURPOSE

To characterize HLA class I antigen expression in non-small cell lung cancer (NSCLC) lesions, and to assess the clinical significance of these molecules' downregulation.

METHODS

One hundred and ninety primary formalin fixed, paraffin embedded NSCLC lesions were stained with HLA class I heavy chain-specific mAb HC-10. Results were scored as percentage of stained tumor cells and categorized into three groups: 0-24% (negative), 25-75% (heterogeneous) and >75% (positive). HLA class I antigen expression was correlated with clinical and pathologic predictors of time to progression and survival and analyzed using the chi-square test. Association between HLA class I antigen expression and survival was assessed using Cox regression models, while controlling for confounders.

RESULTS

HLA class I antigen expression was negative, heterogeneous and positive in 153, 25 and 12 primary NSCLC lesions, respectively. Independent variables significantly associated with survival included tumor stage, PS and weight loss. The median survival times were 40.6, 44.0 and 17.9 months for patients with a HLA class I antigen expression scored as negative, heterogeneous and positive, respectively.

CONCLUSION

HLA class I antigen defects were found with high frequency (93.6%) in NSCLC lesions. HLA class I antigen downregulation was associated with improved survival, although this association was not statistically significant. These results, which parallel similar findings in uveal melanoma and in breast carcinoma, raise the possibility that NK cells may play a role in the control of NSCLC tumors.

Near-work activity and myopia in rural and urban schoolchildren in China

PURPOSE

To examine the prevalence of myopia in rural and urban schoolchildren in Xiamen, China, and to assess the impact of environmental factors on rates of myopia.

METHODS

Second-grade children attending either a city (n=119) or rural (n=91) school in Xiamen, China, were examined using cycloplegic autorefraction and biometry. Detailed questions on socioeconomic status, near-work activity, reading and writing habits, and family histories of myopia were asked in a face-to-face interview using a standard questionnaire.

RESULTS

The prevalence of myopia was 19.3% (95% confidence interval [CI], 12.3, 29) in the city and 6.6% (95% CI, 2.4, 14.3) in the countryside. The average hours per day children spent reading and writing outside of school was 2.2 hours in the city compared with 1.6 hours in the countryside (P<.0001). In both schools, the odds ratio for total reading and writing, adjusted for parental history of myopia, was 2.2 (95% CI, 1.1, 4).

CONCLUSION

These data suggest the prevalence of myopia is higher in the city than in the countryside. One possible explanation for these different rates could be that schoolchildren in the city spend more time reading and writing outside of school compared with children in the countryside. Myopic children in both the city and the countryside spent more time reading and writing compared with nonmyopic children. This increased near-work activity may contribute to the prevalence of myopia.

Role of endothelium-related mechanisms in the pathophysiology of renal ischemia/reperfusion in normal rabbits

The present study addressed the effect of interventions aimed to increase NO in the setting of acute renal ischemia/reperfusion (I/R) in uninephrectomized rabbits. In the 60-minute post-I/R period, L-arginine+superoxide (O2.-) dismutase (SOD) synergistically improved the renal functional (69.4% versus 10.4% of the pre-I/R glomerular filtration rate with or without L-arginine+SOD, respectively; p < .01) and histological parameters (82.9% decrease of medullary congestion in L-arginine+SOD, P < .01 versus vehicle) and blocked the I/R-dependent neutrophil accumulation (89.3% reduction). In spite of these results over the short term, a second set of experiments disclosed that the protection by L-arginine+SOD was no longer present at 24 and 48 hours (plasma creatinine in vehicle-treated versus L-arginine+SOD-treated animals [mg/100 mL]: 24 hours after I/R, 9.4 +/- 1.9 versus 8.07 +/- 0.65; 48 hours after I/R, 11.6 +/- 3.6 versus 9.7 +/- 0.9; P = NS in all the cases). Additional experiments were conducted using a milder 30-minute ischemic model, which showed no significant functional or histological protection by using L-arginine+SOD. In conclusion, our experiments disclosed the following: (1) the critical importance of the interaction between NO and O2.- in the acute protective effect of L-arginine (this effect not only improved renal function and histology but also reduced neutrophil accumulation) and (2) the discordance existing between the immediate protection afforded by L-arginine+SOD and the lack of protection observed at 24 and 48 hours. This finding suggests that a punctual intervention on the NO system at the time of I/R is not sufficient to reduce renal damage over the long term.

Microsporidial keratoconjunctivitis in a healthy contact lens wearer without human immunodeficiency virus infection

PURPOSE

To present a rare case of microsporidial keratoconjunctivitis in an otherwise healthy contact lens wearer without human immunodeficiency virus infection who responded to treatment with systemic albendazole and topical fumagillin.

DESIGN

Interventional case report.

METHOD

A cornea epithelial scraping from a man with unilateral keratoconjunctivitis previously treated with topical steroids was evaluated by modified trichome staining.

MAIN OUTCOME MEASURES

The patient was evaluated for his symptoms, visual acuity, clinical observations, and pathologic examination of corneal scrapes.

RESULTS

Modified trichome staining of an epithelial corneal scraping revealed pinkish to red organisms characteristic of microsporidia. Results of a human immunodeficiency virus (HIV) enzyme-linked immunosorbent assay test were negative. The symptoms of ocular discomfort and clinical signs of keratoconjunctivitis resolved after 2 months of treatment with albendazole and topical fumagillin.

CONCLUSIONS

Ocular infection with microsporidia, although classically occurring in patients with HIV infection, may occur rarely in healthy individuals, especially if previously treated with systemic immune suppression or topical steroids. Microsporidial keratoconjunctivitis should be considered in the differential diagnosis of a contact lens wearer with atypical multifocal diffuse epithelial keratitis.

Role of vascular endothelial growth factor on erythropoietin-related endothelial cell proliferation

The vascular actions of recombinant human erythropoietin (rhEPO) are of particular relevance for fully understanding rhEPO effects. This study examines the mechanisms of action of rhEPO on endothelial cells from bovine aorta (BAEC). First, the studies demonstrated that rhEPO acts on BAEC proliferation as a comitogenic growth factor in the presence of fetal calf serum (FCS). The main experimental findings disclosed that an interaction between rhEPO and vascular endothelial growth factor (VEGF) is instrumental for the growth-promoting action of rhEPO, as shown by the blockade (92.8+/-2.2% inhibition, P < 0.01) of the rhEPO-induced BAEC proliferation by a specific anti-VEGF antibody and by the capability of VEGF for substituting FCS in the induction of rhEPO-related BAEC proliferation (increase in BAEC number in the absence of FCS: 20 U/ml rhEPO alone, 0.3+/-2.8%; 5 x 10(-11) M VEGF alone, 52.9+/-3.1%; 20 U/ml rhEPO + 5 X 10(-11) M VEGF, 117.8+/-6.9%, P < 0.01 between the two agents combined with respect to each agent alone). The existence of a positive interaction between rhEPO and VEGF was further demonstrated by observing an increased cytosolic Ca2+ ([Ca2+]i) mobilization response to VEGF (10(-11)M) in BAEC pretreated or not with 20 U/ml rhEPO (delta[Ca2+]i = 704+/-111 versus 246+/-36 nM, respectively, P < 0.01). To further examine the mechanism of the potentiation of VEGF effect by rhEPO, we analyzed the mRNA expression of the VEGF receptors KDR/flk-1 and flt-1. The results disclosed that BAEC pretreatment with rhEPO upregulated the expression of both KDR/flk-1 and flt-1, therefore providing a structural basis for the aforementioned positive interactions between VEGF and rhEPO. Furthermore, inhibition by genistein suggests that tyrosine phosphorylation was involved in the VEGF receptor upregulation. The mechanisms identified in the present study disclose an interaction at the level of mRNA expression and functional effects between a hormone with predominantly hemopoietic effects, namely, erythropoietin, and an angiogenic factor, namely, VEGF. This relationship between rhEPO and VEGF might be of particular importance in neovascularization processes and in patients receiving rhEPO as a treatment.