Initial clinical experience of patient-specific QA of treatment delivery in online adaptive radiotherapy using a 1.5 T MR-Linac.

Purpose. This study aims to evaluate the performance of a commercial 1.5 T MR-Linac by analyzing its patient-specific quality assurance (QA) data collected during one full year of clinical operation.Methods and Materials. The patient-specific QA system consisted of offline delivery QA (DQA) and online calculation-based QA. Offline DQA was based on ArcCHECK-MR combined with an ionization chamber. Online QA was performed using RadCalc that calculated and compared the point dose calculation with the treatment planning system (TPS). A total of 24 patients with 189 treatment fractions were enrolled in this study. Gamma analysis was performed and the threshold that encompassed 95% of QA results (T95) was reported. The plan complexity metric was calculated for each plan and compared with the dose measurements to determine whether any correlation existed.Results. All point dose measurements were within 5% deviation. The mean gamma passing rates of the group data were found to be 96.8 ± 4.0% and 99.6 ± 0.7% with criteria of 2%/2mm and 3%/3mm, respectively. T95 of 87.4% and 98.2% was reported for the overall group with the two passing criteria, respectively. No statistically significant difference was found between adaptive treatments with adapt-to-position (ATP) and adapt-to-shape (ATS), whilst the category of pelvis data showed a better passing rate than other sites. Online QA gave a mean deviation of 0.2 ± 2.2%. The plan complexity metric was positively correlated with the mean dose difference whilst the complexity of the ATS cohort had larger variations than the ATP cohort.Conclusions. A patient-specific QA system based on ArcCHECK-MR, solid phantom and ionization chamber has been well established and implemented for validation of treatment delivery of a 1.5 T MR-Linac. Our QA data obtained over one year confirms that good agreement between TPS calculation and treatment delivery was achieved.

The effects of Biodentine/polycaprolactone three-dimensional-scaffold with odontogenesis properties on human dental pulp cells.

AIM: To determine the feasibility of using three-dimensional printed Biodentine/polycaprolactone composite scaffolds for orthopaedic and dental applications. The physicochemical properties and the odontogenic differentiation of human dental pulp cells (hDPCs) were investigated. METHODOLOGY: Biodentine was well-suspended in ethanol and dropped slowly into molten polycaprolactone with vigorous stirring. The Biodentine/polycaprolactone composite scaffolds were then fabricated into controlled macropore sizes and structures using an extrusion-based three-dimensional (3D) printer. The mechanical properties, bioactivity, and the proliferation and odontogenic differentiation of human dental pulp cells (hDPCs) cultured on the scaffolds were evaluated. RESULTS: Biodentine/polycaprolactone scaffolds had uniform macropores 550 µm in size with established interconnections and a compressive strength of 6.5 MPa. In addition, the composite scaffolds exhibited a good apatite-forming ability and were capable of supporting the proliferation and differentiation of hDPCs. CONCLUSION: The composite scaffolds fabricated by an extrusion-based 3D printing technique had similar characteristics to Biodentine cement, including bioactivity and the ability to promote the differentiation of hDPCs. These results indicate that the composite scaffold would be a candidate for dental and bone regeneration.

Increased risk of erectile dysfunction among patients with sleep disorders: a nationwide population-based cohort study.

AIMS: Few studies have investigated the relationship between sleep disorders (SD) and erectile dysfunction (ED). Therefore, this study explored whether patients with SD in an Asian population are at an increased risk of developing ED. METHODS: This longitudinal nationwide population-based cohort study investigated the incidence and risk of developing ED in 34,548 men newly diagnosed with SD between 2002 and 2008 from the National Health Insurance Research Database. A total of 138,192 controls without SD were randomly recruited from the general population and frequency matched according to age and sex. The follow-up period began from the date of entering the study cohort until the date of an ED event, censoring, or 31 December 2010. We conducted Cox proportional hazard regression analyses to estimate the effects of SD on the risk of ED. RESULTS: The SD cohort had a 2.11-fold adjusted hazard ratio (HR) of subsequent ED development compared with the non-SD cohort [95% confidence interval (CI) = 1.89-2.37]. The incidence of ED increased with age for both cohorts and was higher for the patients in the SD cohort. Compared with the participants without SD or comorbidities, the patients without SD with any comorbidity exhibited a 1.79-fold risk of developing ED (95% CI = 1.54-2.09); the highest risk was for those with both SD and any comorbidity (HR = 3.34, 95% CI = 2.82-3.95). Furthermore, SD patients who had a particular number of comorbidities showed the dose-response effect of developing ED. CONCLUSION: This nationwide cohort study determined that ED risk evidently increased in SD patients compared with the general population.

A consensus on men's health status and policy in Asia: a Delphi survey.

OBJECTIVE: There is currently no documentation on the availability and implementation of policies related to men's health in Asia. This Delphi study aimed to achieve an Asian consensus on men's health policy based on the opinions and recommendations from men's health key opinion leaders. STUDY DESIGN: A two-phase Delphi online survey was used to gather information from men's health stakeholders across Asian countries. METHODS: All stakeholders were invited to participate in the survey through men's health conferences, personal contacts, recommendations from international men's health organizations and snowballing method. Stakeholders were asked about their concerns on 17 men's health key issues as well as their opinion on the availability and recommendations on men's health policies and programmes in their countries. RESULTS: There were a total of 128 stakeholders (policy makers, clinicians, researchers and consumers), from 28 Asian countries, who responded in the survey. Up to 85% of stakeholders were concerned about various men's health issues in Asia and in their respective country, particularly in smoking, ischaemic heart disease and high blood pressure. There is a lack of men's health policies and programmes in Asia (availability = 11.6-43.5%) and up to 92.9% of stakeholders recommended that these should be developed. CONCLUSIONS: These findings call for policy change and development, and more importantly a concerted effort to elevate men's health status in Asia.

Urinary bladder characteristics via ultrasound as predictors of acute urinary retention in men with benign prostatic hyperplasia.

OBJECTIVE: To determine the clinical utility of urinary bladder and prostate characteristics measured by ultrasound scan in predicting acute urinary retention (AUR) for men with bladder outlet obstruction with an underlying benign prostate hyperplasia (BPH). MATERIALS AND METHODS: Consecutive men aged ≥50 years presenting with lower urinary tract symptoms (LUTS) or AUR were prospectively recruited in this cross-sectional study. International prostatic symptom score (IPSS) and serum prostate-specific antigen (PSA) were recorded. High-resolution ultrasound was used to measure bladder detrusor thickness (DT, mm), prostatic volume (PV, cm3), intravesical prostatic protrusion (IPP, mm), bladder wall thickness (BWT,mm), intravesical volume and bladder radius. The latter two parameters were used to estimate bladder weight (UEBW, g), assuming a spherical bladder. RESULTS: Among selected patients, thirty had AUR while 32 men presented with LUTS only. There were significant differences between those with and without AUR in their age (70.5 vs 66.0, p=0.017), IPSS (24.0 vs 18.5, p=0.009), serum PSA (6.18 vs 1.77, p=0.002), PV (56.7 vs 32.4, p=0.006), BWT (5.0 vs 4.4, p=0.034) and UEBW (39.1 vs 25.0, p=0.0003). Multivariate analysis revealed high IPSS and UEBW to be predictors for AUR. UEBW was the strongest predictor of AUR: area under ROC curve was 0.767, with sensitivity and specificity of 63.3% and 87.5%, respectively, at cut-off point of 35 g. The likelihood ratio for AUR was also best with UEBW≥35 g. CONCLUSIONS: Combined with IPSS, ultrasound determined bladder characteristic, particularly UEBW, is a useful tool in predicting AUR in men with BPH.

Scrotal lump: do not forget tuberculosis!

Scrotal tuberculosis (TB) is rare. Lack of awareness may lead to a misdiagnosis and/or delayed diagnosis of scrotal TB. Clinicians should have a high suspicion index for scrotal TB when facing a patient with a chronic scrotal lump. Since scrotal TB can be medically cured, biopsy of the scrotal lump for pathology study and/or urine polymerase chain reaction (PCR) analysis for M. tuberculosis should be performed first for rapid diagnostic purposes, and therefore unnecessary surgery may thereby be circumvented.

Nurses compliance to hand hygiene practice and knowledge at Klang Valley hospital.

BACKGROUND AND AIMS: Hand hygiene is the most important measure in the prevention of healthcare-associated infections (HCAI). Adherence to hand hygiene protocols in hospital by nurses enables in prevention and control the HCAI. The main aim of the present study was to assess nurses' compliance to hand hygiene practice and knowledge in a hospital. MATERIALS AND METHODS: A descriptive cross-sectional study was conducted in the intensive care units of a hospital in Kuala Lumpur. A total of 84 registered nurses from the intensive care were recruited for this study. A self-administered questionnaire was deployed to measure knowledge and compliance about hand hygiene. RESULTS: The findings showed the total mean and standard deviation of knowledge (60.65±4.213) and compliance (84.65±7.024) to be high among the respondents. There were no significant differences with the knowledge and compliance to hand hygiene with respondents' age groups with a p value >0.05. However, there were significant differences between respondents' years of service with the knowledge and compliance with p values <0.05. The results showed significant differences between respondents' with post basic course with compliance to hand hygiene with a p value <0.05 actual p value added (p = 0.001). There were no significant differences between the respondents' post basic course with knowledge to hand hygiene with p values >0.05 actual p value added (p=0.072). CONCLUSION: Nurses compliance to hand hygiene practice and knowledge was good. Nurses' years of service have great implications on compliance to hand hygiene practice. The study opines that constant reinforcement and motivation are required by the hospital infection control team to impart hand hygiene practice.

SNP array technology: an array of hope in breast cancer research.

Breast cancer is the most common malignancy in women worldwide. The incidence of breast cancer in Malaysia is lower compared to international statistics, with peak occurrence in the age group between 50 to 59 years of age and mortality rates of 18.6%. Despite current diagnostic and prognostic methods, the outcome for individual subjects remain poor. This is in part due to breast cancers' wide genetic heterogeneity. Various platforms for genetics studies are now employed to determine the identity of these genetic abnormalities, including microarray methods like high density single-nucleotide-polymorphism (SNP) oligonucleotide arrays which combine the power of chromosomal comparative genomic hybridization (cCGH) and loss of heterozygosity (LOH) in the offering of higher-resolution mappings. These platforms and their applications in highlighting the genomic alteration frameworks manifested in breast carcinoma will be discussed.

A study of knowledge and attitudes of registered nurses towards pain management in an urban hospital.

BACKGROUND AND AIMS: Nurses play a pivotal role in pain management. Unrelieved pain significantly interferes with patient's quality of life and is of great concern to nurses. The aim of this study was to determine the knowledge level and attitudes of nurses related to pain management. MATERIALS AND METHODS: This descriptive study was conducted in an urban hospital. A total of 84 registered nurses were recruited using a modified version of questionnaire of Knowledge and Attitudes Survey Regarding Pain. RESULTS: The findings showed that respondents possessed good knowledge (99.12±14.810) and attitude (66.00 ±10.415) towards pain management. Fifty five respondents (66%) responded as positive to cultural beliefs affecting their pain management and 65 respondents (77%) viewed that their personal experiences had influenced their practice in pain management. Another 45 respondents (54%) reported they have attended pain course. There was no significant difference in pain management between respondents' year of service, cultural belief and personal experiences (p=>0.05). In terms of knowledge towards to pain management, respondents' age groups of more than 40 years were noted to possess better knowledge (p=0.046), unmarried respondents (p=0.018), and attended pain course (p=0.001) were significant. Attitude towards to pain management was not significant (p≤0.05). CONCLUSION: Nurses' knowledge and attitudes scores were impressive but there is room for further improvement to pain management. Continuing education organized by the hospital had significant impact on the nurses. However, this education course has to be reinforced from time to time in order to improve patients' pain experiences.

An unusual cause of a penetrating injury to the anterior urethra: a thorny situation.

Concurrent penetrating injury to the male external genitalia and the anterior urethra is uncommon. This case illustrates an unusual cause of such an injury, and its subsequent management and outcome. A 69-year-old man had his scrotum and anterior urethra pierced by a long thorn when he fell in his farm. He presented with urine leakage from the scrotal wound each time he micturated. Cystoscopic examination confirmed the cause and extent of the injury, and also facilitated the extraction of the thorn. The injury was allowed time to heal by urinary diversion with a urinary catheter. There were no stricture or fistula formations and the patient remained symptom-free at 3 months follow-up. Careful cystoscopic examination was both diagnostic and therapeutic in this case. A conservative approach is a feasible option in the management of selected cases of penetrating anterior urethral injury.

Testicular mass: do not forget filariasis.

Parasite infestation of the testicular tunica and spermatic cord by filariae are rarely reported and may present with few clinical signs, depending upon the stage. Occasionally, it may mimic a testicular tumor. We present a case of a 29-year-old man who presented with left testicular swelling and discomfort for 4 months. Clinical examination and imaging suggested an intrascrotal cystic lesion with a normal left testis. However, the intraoperative findings revealed a tumor-like mass; hence, a left orchidectomy was performed. However, histopathology reported a diagnosis of a cystic testicular tunica and spermatic cord with parasite infection. Here, we review the literature of scrotal and testicular parasite disease and discuss the course of the appropriate management involved.

Perception of quality of life amongst end stage renal failure patients undergoing haemodialysis.

AIMS: The objective of the study was to examine the quality of life amongst the end stage renal disease (ESRD) haemodialysis patients in Malaysia. MATERIALS AND METHODS: A cross sectional descriptive study was conducted on 72 ESRD patients at a Dialysis Centre in Malaysia. The modified KDQOL-SF™ subscales, kidney disease-targeted scale and 36 item health survey scale questionnaires were used. RESULTS: The overall health rating was 66.73 ± 11.670 indicating good quality of life. There was no significant difference between quality of life for the different domains according to gender (p >0.05). However, there were significant differences between quality of life in the domain of burden of kidney disease. Physical functioning deteriorated significantly with age (p=0.012) while social functioning was lowest in the 50-65 years age group (p=0.037). Those who had no morbidities had significantly better scores on the effects of kidney (p=0.036), burden of kidney disease (p=0.011) and physical functioning (p=0.025). CONCLUSIONS: Patients undergoing haemodialysis have been found to have good quality of life despite having ESRD. It is therefore of paramount importance to constantly monitor the standard of care for these patients to enable them to live their life to the fullest.

Evaluation of power Doppler ultrasonography for prostate biopsy in men with elevated serum prostate specific antigen levels.

OBJECTIVES: To evaluate power doppler ultrasonography (PDU)-directed prostate biopsy in patients with elevated serum prostate specific antigen (PSA) levels. MATERIALS AND METHODS: Men with serum total PSA levels of more than 4 ng/ml undergoing biopsy for the first time were included. Grey-scale transrectal ultrasound (TRUS) and PDU were performed. PDU signal on vascularity accumulation and perfusion characteristics were recorded and graded as normal or abnormal in the peripheral zone of the prostate. Abnormalities were defined on transverse image as radial or arc hypervascularities. A biopsy regime based on Vienna-normogram was performed in all patients. RESULTS: Overall, prostate adenocarcinoma detection rate was 21.4% and abnormal accumulation on PDU signal was identified in 96.7% of those patients (p = 0.01). PDU directed prostate biopsies were positive in 66.7% of the patients with prostate cancer. The sensitivity, specificity, positive predictive value and negative predictive value of PDU signal alone for prostate cancer detection was 96.7%, 24.5% and 96.4% respectively, and PDU guided biopsies were 66.7%, 24.5%, 19.4% and 73% respectively. CONCLUSIONS: The high sensitivity and negative predictive value of PDU makes it useful as an aid for TRUS biopsy in selected patient with previous negative biopsies at risk of harbouring prostate cancer.

Ureteric stone in the presence of existing backache: lessons to learn.

Incidence of urolithiasis is on the rise due to climatic changes especially global warming.The pain due to presence of ureteric stone is a well known identity but many times it may be asymptomatic or even masked by concurrent presence of backache. In the present article, we describe the case of a 43-year-old male who came to the clinic for treatment of backache persisting for more than two years. The patient complained of backache two years back for which he was treated with analgesics and physiotherapy which relieved his pain. No X-ray was taken earlier because the attending clinician thought the backache to be musculo-skeletal in origin. Recently, one day a sudden episode of backache in the midst of night compelled him to seek medical treatment. However, this time a X-ray was performed and it showed the presence of calculi in the right upper pelvis of ureter which measured 1.9 cm vertically. An ultrasound confirmed the diagnosis. The patient was treated with two episodes of shock wave therapy which failed to crush the stone. A Double-J stent was inserted under general anaesthesia. The stone was crushed using a ureteroscope guided laser. The present case report describes how backache in professionals cannot be lightly attended. Even the characteristic groin to loin pain may be absent. All cases of backache should be properly investigated with an X-ray to rule out renal or ureteric calculi.

Capsaicin mediates apoptosis in human nasopharyngeal carcinoma NPC-TW 039 cells through mitochondrial depolarization and endoplasmic reticulum stress.

Capsaicin, a pungent compound found in hot chili peppers, has been reported to have antitumor activities in many human cancer cell lines, but the induction of precise apoptosis signaling pathway in human nasopharyngeal carcinoma (NPC) cells is unclear. Here, we investigated the molecular mechanisms of capsaicin-induced apoptosis in human NPC, NPC-TW 039, cells. Effects of capsaicin involved endoplasmic reticulum (ER) stress, caspase-3 activation and mitochondrial depolarization. Capsaicin-induced cytotoxic effects (cell death) through G0/G1 phase arrest and induction of apoptosis of NPC-TW 039 cells in a dose-dependent manner. Capsaicin treatment triggered ER stress by promoting the production of reactive oxygen species (ROS), increasing levels of inositol-requiring 1 enzyme (IRE1), growth arrest and DNA-damage-inducible 153 (GADD153) and glucose-regulated protein 78 (GRP78). Other effects included an increase in cytosolic Ca(2+), loss of the mitochondrial transmembrane potential (ΔΨ(m)), releases of cytochrome c and apoptosis-inducing factor (AIF), and activation of caspase-9 and -3. Furthermore, capsaicin induced increases in the ratio of Bax/Bcl-2 and abundance of apoptosis-related protein levels. These results suggest that ER stress- and mitochondria-mediated cell death is involved in capsaicin-induced apoptosis in NPC-TW 039 cells.

Diagnostic value of procalcitonin in pleural effusions.

This study was to determine the diagnostic value of procalcitonin (PCT) in the differentiation of infectious and non-infectious causes of pleural effusion. From January 2005 to April 2005, we measured the PCT levels of pleural effusion from 76 patients using an immunoluminometric assay. The types of pleural infusions studied were para-pneumonic effusion (n = 26), empyema (n = 7), tuberculous pleurisy (n = 8), malignant pleural effusion (n = 25) and transudative pleural effusion (n = 8). The PCT levels were low in transudative pleural effusions (0.188 ± 0.077 ng/mL) and tuberculous pleurisy (0.130 ± 0.069 ng/mL), but high in empyema (5.147 ± 3.056 ng/mL), para-pneumonic effusion (1.091 ± 0.355 ng/mL), and malignant pleural effusion (0.241 ± 0.071 ng/mL). The receiver-operating characteristic curve analysis for an optimal discrimination between empyema and para-pneumonic effusion from non-para-pneumonic effusion could be performed at a cut-off point of 0.18 ng/mL with area under the curve of 0.776 (sensitivity: 69.7%, specificity: 72.1%). The correlation was found between pleural effusion PCT and serum PCT levels in 16 patients (r² = 0.967, p < 0.001). In conclusion, a high pleural effusion PCT level suggests the presence of empyema and para-pneumonic effusion.

Clinicopathological features and survival of testicular tumours in a Southeast Asian university hospital: a ten-year review.

INTRODUCTION: Testicular cancer mainly affects young men worldwide. There is lack of published data on patients with this malignant condition from the Southeast Asian region. The aim of this study was therefore to determine the clinicopathologic features of testicular cancer patients treated in a Southeast Asian university hospital and their overall survival rate. MATERIALS AND METHODS: This was a retrospective study of testicular cancer patients treated between January 2001 and February 2011. Their epidemiological data, clinical presentation, pathologic diagnosis, stage of disease and treatment were gathered and the overall survival rate of this cohort was analyzed. RESULTS: Thirty-one patients were included in this study. The majority of them were of Malay ethnicity. The average age at presentation was 33.7 years. The commonest testicular cancer was non-seminomatous germ cell tumour, followed by seminoma, lymphoma and rhabdomyosarcoma. More than half of all testicular germ cell tumour (GCT) patients had some form of metastasis at diagnosis. All the patients were treated with radical orchidectomy. Adjuvant chemotherapy was given to those with metastatic disease. Four seminoma patients received radiotherapy to the para-aortic lymph nodes. The 5-year survival rate for all testicular cancers in this cohort was 83.9%. The survival rate was 88.9% in 5 years when GCT were analyzed separately. CONCLUSION: GCT affects patients in their third and fourth decades of life while lymphoma patients are generally older. Most of the patients treated for GCT are of Malay ethnicity. The majority have late presentation for treatment. The survival rate of GCT patients treated here is comparable to other published series in other parts of the world.

Retrograde intrarenal surgery for renal stones smaller than 2 cm.

INTRODUCTION: Extracorporeal shock wave lithotripsy (ESWL) is accepted as the gold standard treatment for renal stones that are smaller than 2 cm. Recently, retrograde intrarenal surgery (RIRS) has been introduced as another form of treatment. We report our experience in dealing with renal stones smaller than 2 cm using RIRS as the primary treatment and following failed ESWL. METHODS: A retrospective analysis was conducted over a five-year period on patients with stone(s) measuring less than 2 cm each and who had undergone RIRS. The patients were divided into two groups: RIRS as the primary procedure and RIRS post-ESWL. RESULTS: A total of 46 patients underwent RIRS in our institute. The total stone clearance rate was 61 percent. The clearance rate was better for RIRS as the primary procedure when compared to RIRS as an adjunct procedure (70 percent versus 52 percent; p-value is 0.23). Patients with mid-pole stones achieved an 80 percent stone clearance rate as compared to 60 percent for those with lower pole stones. The clearance rate for upper pole stones was only 29 percent. When RIRS was the primary procedure for lower pole stones, the success rate was 75 percent, compared to 56 percent when it was used as an adjunct procedure post-ESWL. CONCLUSION: For renal stones measuring less than 2 cm, the stone clearance rate for RIRS was as good as that for EWSL as a primary procedure and achieved a good clearance rate following the failure of ESWL.

Reproductive performance of seven strains of the tomato red spider mite Tetranychus evansi (Acari: Tetranychidae) at five temperatures.

The tomato red spider mite Tetranychus evansi Baker et Pritchard occurs on solanaceous plants, and causes serious damage to a variety of crops in Africa and Europe. In 2001 this species was also found in Japan, on nightshade (Solanum nigrum L.), and its invasion to solanaceous of agricultural importance is feasible. To evaluate its potential severity as a pest, the present study assessed the life-history parameters, such as the rate of development and the intrinsic rate of natural increase (r(m)), on S. nigrum for T. evansi collected on seven sites worldwide. Increasing temperatures between 15 and 32.5°C significantly increased the developmental rate of the seven strains while immature developmental duration was about the same at 32.5-40°C. The rate of egg-to-adult development [(% hatch) × (% survival)] exceeded 88% at temperatures between 15 and 37.5°C. The lower thermal thresholds (LT) were 11.9-12.5°C for both egg-to-adult and egg-to-egg development. The optimum developmental temperatures ranged from 36.7 to 43.8°C and the upper developmental threshold (UT) ranged from 45.2 to 59.4°C. The r (m)-values became higher with temperature increasing from 15 to 35°C. The r (m)-values at 25°C ranged from 0.265 to 0.277 which are relatively high for species of the genus Tetranychus. These results indicate that T. evansi after invasion into Japan has the potential to become a serious pest on solanaceous crops, just the same as in Africa and Europe.

Androgen decreases dopamine neurone survival in rat midbrain.

Clinical studies show that men are more likely to develop disorders affecting midbrain dopaminergic pathways, such as drug addiction and Parkinson's disease (PD). Although a great deal of focus has been given to the role of oestrogen in the maintenance of midbrain dopaminergic pathways, little is known about how testosterone influences these pathways. In the present study, we used stereological analysis of tyrosine hydroxylase-immunoreactive (TH-IR) cell bodies to determine how testosterone influences the dopaminergic cell bodies of the substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA). Rats and mice were castrated at postnatal day (PN) 60, and these midbrain cell populations were counted on PN 90. One month after castration, TH-IR cell number had increased in the SNpc and VTA of rats and mice. Replacement with testosterone or the non-aromatisable analogue dihydrotestosterone (DHT) in castrated animals reduced TH-IR cell number in the SNpc and VTA in rats. In mice, the decrease of TH-IR cell number with testosterone or DHT replacement was observed only in the SNpc. The apparent increase in TH-IR neurone number after castration is not explained by an increase in TH expression because the number of nondopaminergic cells (TH-immunonegative, TH-IN) did not decrease proportionally after castration. TH-IN cell number did not change after castration or hormone replacement in rat or mouse SNpc or VTA. These findings suggest that testosterone may play a suppressive role in midbrain dopaminergic pathways.