[Study on the prognostic value of preoperative anti hepatitis B virus therapy in patients with hepatocellular carcinoma complicated with microvascular tumor thrombus and establishment of survival prediction model].

Objective: To explored the effect of preoperative antiviral therapy on the prognosis of microvascular tumor thrombi patients, and to established a prognostic prediction model for these patients after radical resection of liver cancer. Methods: The clinicopathological and survival data of hepatocellular carcinoma patients with microvascular tumor thrombus who underwent radical resection in the Third Affiliated Hospital of Sun Yat-sen University from January 1, 2013 to December 31, 2015 were retrospectively collected. Kaplan-Meier method was used to calculate the survival curve, and log-rank test was used to compare the prognosis of patients with and without antiviral treatment before operation. Univariate and multivariate Cox proportional hazard regression model was used to screen predictive factors. R software was used to make predictive nomogram, and discrimination and calibration degree were used to evaluate the prediction model. Results: Among all 153 patients, 22 were female and 131 were male, aged (51.3±11.7) years. The preoperative antiviral therapy significantly improved overall survival and recurrence-free survival (χ2=41.423, 54.389; both P<0.001). According to the results of multivariate and regression analysis, preoperative antiviral therapy (HR=0.301,95%CI:0.171-0.532,P<0.001), alpha fetoprotein (HR=1.226,95%CI:1.157-1.776,P=0.032) and tumor size (HR=1.008,95%CI:1.001-1.016,P=0.02) were important prognostic factors for overall survival. The area under curve value of 3-year survival prediction model was 0.749(95%CI: 0.712-0.782), and that of 5-year survival prediction model was 0.755(95%CI: 0.724-0.793), with good calibration. Conclusions: Preoperative anti hepatitis B virus(HBV) therapy can significantly improve the prognosis of patients with hepatocellular carcinoma complicated with microvascular tumor thrombus, we develope the prediction models of 3-year and 5-year survival rate that can improve the reference for clinical work and benefit patients.

[Relationship of operation manner and postoperative recurrence of hepatocellular carcinoma].

Hepatocellular carcinoma (HCC) owns the high morbidity and mortality rates. Surgical resection is still the major pathway for the longer survival of HCC patients. Postoperative recurrence and metastasis have become the key impairment of prognosis of HCC patients. The relationship between tumor recurrence and surgical manner underwent by HCC patients is complicated and multiple factors are included. When the liver tumor was pressured during operation, tumor cells could be squeezed into blood flow via the broken vessels, which resulted in tumor metastasis. Besides, ischemia-reperfusion injury induced by Pringle maneuver during the liver blood blockade resulted in the immune destruction of liver and induced tumor recurrence.The destruction of physical barriers consisted of interstitial cells and normal liver cells was also a key factor for tumor recurrence. This paper summarizes the possible relationship between postoperative recurrence and surgical manner in HCC patients to provide the preventive suggestions for the postoperative recurrence of HCC patients.

[Angiopoietin-2 regulates vessels encapsulated by tumor clusters positive hepatocellular carcinoma nest-type metastasis via integrin α5ß1].

Objective: To investigate the molecular mechanism of nest metastasis in blood vessels encapsulated by tumor clusters (VETC) positive hepatocellular carcinoma (HCC). Methods: A total of 72 paraffin embedded HCC tissue samples were collected. Immunohistochemistry staining with CD34 (vascular endothelial cell marker protein) was used to observe the morphological manifestations of VETC cancer nests in primary tumors, bile duct cancerous thrombi and portal vein cancerous thrombi, and to study the characteristics of hematogenous metastasis of VETC cancer nests. Bioinformatics was used to predict the key proteins closely related to VETC cancer nest formation. Immunohistochemistry was used to detect the expression of angiogenin-2 (Ang-2), integrin α5, Integrin ß1, and cyclooxygenase-2 (COX-2) proteins in HCC. Transwell cell migration assay was used to detect the effect of Ang-2/integrin α5ß1 protein on the migration ability of endothelial cells and HCC cells. Western blotting was used to detect the effect of Ang-2/integrin α5ß1 protein on the activity of focal adhesion kinase (FAK) protein. Results: Of the collected HCC specimens, 27 cases (27/72) were VETC (+), including 3 cases with biliary duct cancerous thrombus, 5 cases with portal vein cancerous thrombus, and 3 cases with both biliary duct cancerous thrombus and portal vein cancerous thrombus. VETC (+) HCC could metastasize to portal vein, bile duct, and liver in the form of cancer nest, and the nests retain their intact structure. Ang-2, integrin α5 and integrin ß1 were overexpressed in tumor cells and endothelial cells of VETC (+) HCC nests, while COX-2 was only overexpressed in tumor cells of VETC (+) HCC nest. Ang-2 could promote the migration of HCC cell [(121±12) vs (186±11), P<0.01] and endothelial cells [(81±7) vs (163±14), P<0.01]. Integrin α5ß1 activation antagonist ATN-161 could significantly block the ability of Ang-2 to promote the migration of HCC cells [(185±10) vs (135±9), P<0.05] and endothelial cells [(156±14) vs (103±6), P<0.05]. ATN-161 could significantly block the phosphorylation of FAK in HCC and endothelial cells induced by Ang-2. Conclusions: VETC (+) HCC could metastasize as a whole in a nested form, and possesses a specific regulatory protein. Ang-2/α5ß1/FAK might be potential protein targets in the treatment of VETC (+) HCC nest-type metastasis.

Using real-time sound touch elastography to monitor changes in transplant kidney elasticity.

AIM: To use sound touch elastography (STE) to assess the changes of renal cortex among different complications following renal transplantation. MATERIALS AND METHODS: A total of 31 patients with renal dysfunction after renal transplantation underwent an ultrasound-guided biopsy for pathological examination with conventional and STE ultrasound. The maximum elastic modulus (Emax) was determined, and the biopsy specimen was evaluated for evidence of significant differences among four different complications: drug-induced renal damage, acute rejection, chronic allograft nephropathy (CAN), and BK virus (BKV) nephropathy. Receiver operator characteristics were used to compare the diagnostic efficacy of STE ultrasound according to the pathological results. RESULTS: The quantitative index Emax of the STE technique was statistically significant among the four different complications (p<0.05). The distribution of the magnitude of Emax in the renal cortex was BKV nephropathy > CAN > acute rejection > drug induced renal damage. The renal cortex Emax was statistically different for the severity of renal fibrosis and tubular atrophy (p<0.05). CONCLUSION: Each of the four different complications of transplantation influenced the Emax of the renal cortex differently. Emax can be used to assess the severity of renal fibrosis and tubular atrophy.

[Research progress in the Hepatobiliary Surgery operation of hepatic hilar plate system].

An estimate of about 50% of new liver cancer cases worldwide occur in China every year.Surgical resection is still the major treatment choice for longer survival of patients with hepatocellular carcinoma. Blocking hepatic blood flow and reducing intraoperative bleeding ensure the success of the operation. Anatomic separation of hepatic hilar region is the precondition of hepatic inflow occlusion. The hepatic hilar plate system involves a thick layer of connective tissue covering the hepatic inflow ducts of hepatic hilar region. The descending part of hilar plate assists in reducing the anatomical difficulty of the hepatic hilar region. The "forth porta hepatis" that is hidden in the hepatic hilar plate system involves the accumulation area of "short hepatic portal veins" .The communicating branch vessels between the hepatic inflow vessels form the anatomical basis in reducing the indocyanine green fluorescence stain effect.The relatively fixed position of the hepatic portal plate is considered as a positioning marker for accurate liver resection. The intrahepatic Glisson sheath is connected with thick connective tissue of the hepatic portal panel system, and is regarded as the physical barrier in limiting the proliferation and hypertrophy of hepatocytes and continuation of hepatic portal panel system in the liver.This paper summarizes the anatomy and application of hepatic hilar plate system during hepatobiliary surgery.

Higher liver stiffness scores are associated with early kidney dysfunction in patients with histologically proven non-cirrhotic NAFLD.

AIM: The association between Liver fibrosis (LF), as assessed by either histology or Liver stiffness measurement (LSM), and the presence of Early kidney dysfunction (EKD) was investigated in this study, as was also the diagnostic performance of LSM for identifying the presence of EKD in patients with Non-alcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS: A total of 214 adults with non-cirrhotic biopsy-proven NAFLD were recruited from two independent medical centres. Their histological stage of LF was quantified using Brunt's criteria. Vibration-controlled Transient elastography (TE), using M-probe (FibroScan®) ultrasound, was performed in 154 patients and defined as significant when LSM was≥8.0kPa. EKD was defined as the presence of microalbuminuria with an estimated glomerular filtration rate≥60mL/min/1.73 m2. Logistic regression modelling was used to estimate the likelihood of having EKD with NAFLD (LSM-EKD model). RESULTS: The prevalence of EKD was higher in patients with vs without LF on histology (22.14% vs 4.82%, respectively; P<0.001) and, similarly, EKD prevalence was higher in patients with LSM≥8.0kPa vs LSM<8.0kPa (23.81% vs 6.59%, respectively; P<0.05). The area under the ROC curve of the LSM-EKD model for identifying EKD was 0.80 (95% CI: 0.72-0.89). LF detected by either method was associated with EKD independently of established renal risk factors and potential confounders. CONCLUSION: LF was independently associated with EKD in patients with biopsy-proven NAFLD. Thus, TE-measured LSM, a widely used technique for quantifying LF, can accurately identify those patients with NAFLD who are at risk of having EKD.

LncRNA HAND2-AS1 inhibits proliferation and promotes apoptosis of chronic myeloid leukemia cells by sponging with micRNA-1275.

OBJECTIVE: The long noncoding RNA (lnc) HAND2-AS1 is down-regulated and microRNA-1275 (miR-1275) is up-regulated in many types of cancers. However, their expressions and the relationship between HAND2-AS1 and miR-1275 in chronic myeloid leukemia (CML) remain unknown and to be further investigated. PATIENTS AND METHODS: Bone marrow samples from 30 CML patients and 10 healthy donors were collected; HAND2-AS1 and miR-1275 were detected by RT-PCR. The correlation between HAND2-AS1 and miR-1275 was analyzed. After lentiviral (LV) HAND2-AS1 and miR-1275 inhibitors were respectively transfected into KCL22 and K562 cells, the expressions of HAND2-AS1 and miR-1275 were detected by RT-PCR. MTT assay was performed to evaluate cell viability and mRNA and proteins levels of Bcl-2, Caspase-3, MMP-2, MMP-9 were detected by RT-PCR and Western blot (WB). Luciferase reporter assay was performed to explore the binding site of HAND2-AS1 and miR-1275. RESULTS: Results showed that HAND2-AS1 was significantly downregulated than healthy control (p<0.05), and HAND2-AS1 expressions on stages of AP and BP were much lower than that of CP (p<0.05). The miR-1275 expression was significantly upregulated than healthy control (p<0.05), and the expressions in stages of accelerated phase (AP) and blast phase (BP) were much higher than that in the stage of chronic phase (CP) in CML (p<0.05). Furthermore, HAND2-AS1 was negatively correlated with miR-1275 in CML, but not in healthy control (p<0.05). After lentiviral HAND2-AS1 transfection, the HAND2-AS1 expression was significantly up-regulated while miR-1275 was significantly down-regulated (p<0.05). Then, the cell proliferation was inhibited after 72 h. Furthermore, the mRNA and protein levels of Bcl-2, MMP-2 and MMP-9 were significantly down-regulated (p<0.05), while the expression of Caspase-3 was significantly up-regulated (p<0.05). Luciferase reporter assay showed that HAND2-AS1 was a target gene of miR-1275. And after treating with miR-1275 inhibitor, HAND2-AS1 was significantly upregulated (p<0.01) and cell proliferation was inhibited (p<0.01). Furthermore, the expressions of Bcl-2, MMP-2, and MMP-9 were significantly decreased, while Caspase-3 was significantly increased (p<0.01). CONCLUSIONS: HAND2-AS1 was downregulated and miR-1275 was upregulated in CML, and HAND2-AS1 inhibited proliferation and promoted apoptosis of CML cells by sponging with microRNA-1275, which might be a novel therapeutic target for CML.

[Proton nuclear magnetic resonance spectroscopy recognition of metabolic patterns in fecal extracts for early diagnosis of colorectal cancer].

Objective: To characterize the metabolic " fingerprint" of fecal extracts for diagnosis of early-stage colorectal cancer(CRC)using proton nuclear magnetic resonance spectroscopy(1H-NMR)-based metabolomics coupled with pattern recognition. Methods: From January 2014 to December 2014, we collected fecal samples at the Second Affiliated Hospital of Shantou University Medical College, from 25 patients with colorectal adenomas(CR-Ad), 20 with stage Ⅰ/Ⅱ CRC, and 32 healthy controls(HCs). The patients were diagnosed by histopathology. No subjects had any complicating diseases. HCs showed no abnormalities from blood tests, endoscopic examination, diagnostic imaging, and/or medical interviews. We excluded participants who used antibiotics, NSAIDS, statins, or probiotics within two months of study participation, and any patients who underwent chemotherapy or radiation treatments prior to surgery. We used orthogonal partial least-squares-discriminant analysis(OPLS-DA)for pattern recognition(dimension reduction)on 1H-NMR processed data(1H frequency of 400.13 MHz), to find metabolic differences among CR-Ad, carcinoma and HC fecal samples; and receiver operating characteristic(ROC)analysis to determine the diagnostic value of the fecal metabolic biomarkers. Results: Fecal samples were collected from 20 patients with Stage Ⅰ/Ⅱ CRC(11 M, 9 F, median age(52±13)years), 25 with CR-Ad(14 M, 11 F, median age(53 ± 11)years)and 32 HCs(15 M, 17 F, median age(53 ± 14)years). OPLS-DA clearly distinguished CR-Ad and stage Ⅰ/Ⅱ CRC from HC samples, based on their metabolomic profiles. Relative signal intensities in HCs were significantly lower than in the cancer patients for butyrate(HC: 23.0±6.0; CR-Ad: 18.0±5.0; CRC: 14.0±6.0; Z=-2.07, P=0.008), acetate(HC: 45.0±11.0; CR-Ad: 31.0±11.0; CRC: 24.0±8.0; Z=- 2.32, P=0.011), propionate(HC: 26.0 ± 7.0; CR-Ad: 22.0 ± 6.0; CRC: 19.0 ± 5.0; Z=- 2.43, P=0.032), glucose(HC: 37.0±7.0; CR-Ad: 31.0±7.0; CRC: 26.0±8.0; Z=-2.07, P=0.044)and glutamine(HC: 4.5±2.0; CR-Ad: 4.9 ± 1.0; CRC: 5.4 ± 1.0; Z=2.21, P=0.044). However, relative signal intensities in HCs were significantly higher than in patients for lactate(HC: 4.8±1.0; CR-Ad: 6.9±2.0; CRC: 4.8± 1.0; Z=2.02, P= 0.038), glutamate(HC: 3.2 ± 2.0; CR-Ad: 4.9 ± 1.0; CRC: 3.2 ± 2.0; Z=2.21, P=0.044)and succinate(HC: 12.0±2.0; CR-Ad: 15.0±3.0; CRC: 12.0± 2.0; Z=2.25, P=0.011). Among the potential biomarkers, acetate at 1.92 ppm, and succinate at 2.41 ppm displayed relatively high area under ROC, with sensitivity and specificity both >90%, to distinguish early-stage CRC patients from HCs. Conclusion: Fecal metabolic profiles distinguish of HCs from patients with CRC patients, even in the early stages(stage Ⅰ/Ⅱ), highlighting the potential of NMR-based fecal metabolomic fingerprinting as tools for early CRC diagnosis.

Initial experiences with laparoscopy and flexible ureteroscopy combination pyeloplasty in management of ectopic pelvic kidney with stone and ureter-pelvic junction obstruction.

To demonstrate the safety and efficacy of combine laparoscopy and flexible ureteroscopy to treat ectopic pelvic kidneys with ureteropelvic junction obstruction (UPJO) and stones. 16 patients of ectopic pelvic kidneys with ureteropelvic junction obstruction and stones were treated with laparoscopy and flexible ureteroscopy (FURS). The operative time, required dose of tramadol, visual analog pain scale (VAPS), postoperative day, stone-free rates (SFRs), perioperative complications, and serum creatinine were evaluated. The SFRs were evaluated with noncontrasted renal computed tomography (CT). Intravenous pyelography (IVP) and CT scan were used to evaluate the UPJO. Stone-free status was defined as absence of stone fragments in kidney or the size of that is less than 3 mm. Operation time from 118 to 225 min, average time (171 ± 28) min; lithotomy time from 16 to 45 min, average time (32 ± 6) min. Average tramadol required at the first day postoperation was (118 ± 49.6) mg; at the second day was (78 ± 24.8) mg. VAPS score at 24 h (5.0 ± 0.7), VAPS score at 48 h (2.5 ± 0.8). Postoperative day (3.9 ± 0.6) days. Stone-free rate was 100%. Average serum creatinine was (88.7 ± 24.3) mol/L before surgery and (92.8 ± 21.6) mol/L after surgery. No major complication. No stone and obstruction recurrence in the follow-up of average 29.3 months. Combined FUR and LC is a good option for patient of ectopic pelvic kidney with renal stone and UPJO. From our initial experience, the SFRs and the effect of pyeloplasty are satisfactory and without major complication, the operative time is acceptable.

A new subtype of crossed fused ectopia of the kidneys.

Crossed fused renal ectopia is a rare congenital anomaly; here, we report a new subtype of crossed fused renal ectopia associated with the retroiliac megaureter and thoracic scoliosis deformity. It is beyond the traditional classification of crossed fused renal ectopia. There are 2 kidneys in the left and hydronephrosis of the upper kidney, the right kidney crossed over and fused with the lower kidney of the left. It is never seen in previous reports. Recurrent infection was cured by resecting the hydronephrosis of the upper kidney and retroiliac megaureter.

Triptolide inhibits the multidrug resistance in prostate cancer cells via the downregulation of MDR1 expression.

Triptolide (TPL) is a diterpenoid triepoxide derived from the Chinese herb Tripterygium wilfordii and possesses anti-tumor activity against a range of cancer cells. However, the effect of TPL on prostate cancer cells and its potential to overcome multidrug resistance (MDR) have not been explored. Therefore, in this study we used prostate cancer cell line DU145 as the experimental model and established DU145/ADM cell line resistant to adriamycin (ADM). Our results showed that TPL inhibited the proliferation and induced the cell cycle arrest and apoptosis of DU145 cells in a dose and time dependent manner. TPL decreased the levels of Cyclin D1 and anti-apoptotic protein Bcl-2, and increased the levels of pro-apoptotic proteins Fas and Bax. Furthermore, we found that TPL restored the sensitivity DU145/ADM cells to ADM in a dose dependent manner, and this was accompanied by the inhibition of MDR1 expression at both mRNA and protein levels. Taken together, these results provide strong evidence that TPL overcomes MDR in prostate cancer cells by downregulating MDR1 expression, and suggest that TPL is a promising agent for prostate cancer therapy, especially for chemoresistant prostate cancer.

Genitourinary toxicity of ketamine.

Ketamine is a relatively new recreational drug used by youngsters in recent decades. Its toxic effects on the genitourinary system were first reported in 2007, and now attract extensive attention from urologists, pharmacologists, and toxicologists all over the world. As many front-line health professionals and medical social workers are still unaware of this new clinical entity and an increasing number of the drug users seek help for urological symptoms, this mini-review aimed to summarise the clinical features and possible mechanisms of ketamine-induced genitourinary toxicity. By raising public awareness of these toxic effects, the authors hope that the contents of this review will be widely disseminated not only to medical professionals, but also to relevant government departments and the general public.

Prostaglandin-D synthetase induces transcription of the LH beta subunit in the primary culture of chicken anterior pituitary cells via the PPAR signaling pathway.

Downstream effects of prostaglandin-D synthetase (PGDS) in a primary culture of chicken (Gallus gallus) anterior pituitary cells were investigated to study how PGDS regulated laying in hens. Either PGDS downstream metabolite, PGD(2) or PGJ(2), elevated LHB mRNA and LHB protein levels in dose- and time-dependent manners, and treatment with arachidonic acid (1 microM) alone upregulated 15-deoxy-Delta(12,14)-PGJ(2) (15-d-PGJ(2); derived from PGJ(2))/PGJ(2), LHB mRNA, and LHB protein levels (P<0.05) in the primary culture of chicken pituitary anterior cells. Transfection of the plasmid Enhanced Green Fluorescent Protein-PGDS plasmid into these cells in medium containing 1 microM arachidonic acid additionally increased 15-d-PGJ(2)/PGJ(2), LHB mRNA, and LHB protein levels (P<0.05). In the hypothalamus/pituitary gland of laying hens, there was a high correlation (r=0.64; P<0.05) between PGDS and the peroxisome proliferator-activated receptor A (PPARA) mRNA level in a high egg production strain, the L2 Taiwan country chickens. In commercial Single-Comb White Leghorn layers, there were high correlation coefficients between PGDS and PPARA (r=0.65; P<0.05) and between PGDS and PPARG (r=0.67; P<0.01) mRNA levels. A broad-range PPARs agonist, GW9578 (5 to 500 nM), enhanced LHB mRNA and LHB protein levels (P<0.05). The PPARA-specific (GW6471) and PPARG-specific (T0070907) antagonists suppressed endogenous LHB mRNA and LHB protein levels (P<0.05); in addition, both antagonists attenuated arachidonic acid-induced LHB mRNA levels (P<0.05) and PGDS-induced (in the presence of 1 microM arachidonic acid) LHB mRNA and LHB protein (P<0.05) levels in the primary culture of chicken anterior pituitary cells. Higher LHB mRNA/LHB protein ratios in PGD(2)-, PGJ(2)-, arachidonic acid-, PGDS-, and GW9578-induced as well as GW6471- and T0070907-suppressed anterior pituitary cells suggested that LHB transcription occurred before translation. In conclusion, PGDS induced LHB transcription and subsequent translation via the PPAR signaling pathway.

Ginseng flowers stimulate progesterone production from bovine luteal cells.

Our previous report first showed evidence that polysaccharides isolated from ginseng leaves obtained from Jilin, China possess luteotropic activities. In this study, we made further investigations on the root and flowers of Korean ginseng by means of the same bioassay system described briefly as follows. Frozen-thawed bovine luteal cells (1 x 10(5) cells/ml/well) in M199 were incubated in 24-well culture plates at 37 degrees C in a 5 % CO2 incubator. Ten microl of tested drugs with 1, 10 and 100 microg/ml were added into each well. After 4- and 24-hr incubation, the media were harvested and assayed for progesterone by an enzyme immunoassay. The production of progesterone from cells is the indicator for evaluating the action of tested drugs. Results showed that hot water extracts ofginseng flowers (GF-1) with 10 to 100 microg/ml significantly increased progesterone production, whereas those from ginseng root (GR-1) could not. Crude polysaccharides (GF-2) isolated from GF-1 is the active component and the small molecules (mw < 10,000 dalton) are excluded, indicating that the ginseng root has no luteotropic activities, but the polysaccharides of ginseng flowers have.

Early and late long-term effects of vasectomy on serum testosterone, dihydrotestosterone, luteinizing hormone and follicle-stimulating hormone levels.

PURPOSE: We investigated whether the association between vasectomy and prostate cancer has a hormonal basis. MATERIALS AND METHODS: We examined serum testosterone, dihydrotestosterone, luteinizing hormone and follicle-stimulating hormone levels by radioimmunoassay on 91 pairs of men who did and did not undergo vasectomy. RESULTS: Men who underwent vasectomy 10 to 19 years previously had higher dihydrotestosterone levels than age matched controls. In men who underwent vasectomy 20 years or more ago testosterone was higher than in corresponding controls. No statistically significant difference in luteinizing hormone and follicle-stimulating hormone levels was noted between the men who had had vasectomy and controls. CONCLUSIONS: Our results indirectly support the hypothesis that there is an elevated risk of prostate cancer among men who underwent vasectomy 20 or more years previously.

PIP: Researchers compared data on 91 men who had undergone vasectomy at least 10 years earlier with data on 91 healthy men matched for age, weight, height, and neighborhood who had not undergone vasectomy to examine whether the link between vasectomy and prostate cancer is based on changes in serum hormone levels. All the men lived in suburban Xiangtan in Hunan Province, China. Cases had a higher mean serum dihydrotestosterone level than controls (1.18 vs. 1.05 nmol/l; p 0.05). Yet men who had undergone vasectomy less than 20 years earlier not only had a higher dihydrotestosterone level than age-matched controls (1.46 vs. 1.22 nmol/l; p 0.01) but had a lower testosterone/dihydrotestosterone ratio (14.5 vs. 20.1; p 0.005). On the other hand, men who had undergone vasectomy more than 20 years earlier had a higher testosterone level than age-matched controls (27.2 vs. 23.9 nmol/l; p 0.05). Men who had undergone vasectomy when they were less than 35 years old had a higher FSH level and those who were 35-39 years old at vasectomy had a higher dihydrotestosterone level than age-matched controls (19.5 vs. 14.8 mIU/ml and 1.31 vs. 1.09 nmol/l) (p 0.05). Even though men who were at least 40 years old at vasectomy had a higher dihydrotestosterone level than matching controls (1.24 vs. 1.09 nmol/l), the difference was not statistically significant. These findings suggest that vasectomy may cause a reduction in testosterone levels by minimizing the conversion from testosterone to dihydrotestosterone in the long term. Thus, they support the hypothesis that a long-term effect of vasectomy may be an elevated risk of prostate cancer. More research is needed to confirm or refute this hypothesis.