Standard clinical computed tomography fails to precisely visualise presence, course and branching points of deep cerebral perforators.

BACKGROUND: Standard computed tomography (CT) images have earned a well-established position in neuroimaging. Despite that, CT is somehow limited by its resolution, which does not enable to distinctively visualise structures smaller than 300 µm in diameter. Perforating arteries, most of which measure 100-400 µm in diameter, supply important subcortical structures (thalamus, basal ganglia, internal capsule). Consequently, pathologies affecting these vessels (e.g. lacunar strokes) can have a devastating clinical outcome. The aim of our study was to assess standard CT's ability to visualise perforators and compare it with microscopic and micro-CT pictures. MATERIALS AND METHODS: We have obtained 6 brainstem and 17 basal ganglia specimens. We infused them with barium sulphate contrast medium administered into either vertebral or internal cerebral artery. After that, the specimens were fixed in formalin and subsequently a series of CT, micro-CT and microscopic examinations were performed. RESULTS: The median number of visualised perforators in brainstem and basal ganglia specimens was 8 and 3, respectively for CT and 18 and 7 for micro-CT (p < 0.05). Standard CT failed to clearly visualise branching points and vessels smaller than 0.25-0.5 mm (1-2 voxels) in diameter. Parallel vessels, like lenticulostriate arteries could not be differentiated in standard CT due to their proximity being smaller that the resolution. CONCLUSIONS: Basing on our results, we infer that CT is a poor modality for imaging of the perforators, presenting both quantitative and qualitative flaws in contrast with micro-CT.

Dental services market in Poland and its impact on the health decisions of patients and doctors.

AIM: The aim of the paper is to verify the impact of the current dental services market in Poland on the society decisions regarding dental treatment as well as to assess the differences in the valuation of commercial and public dental services. METHODS: Study Design: In the first step 1,444 subjects including children, adults and elderly were subjected to a questionnaire survey to characterise them in terms of sex, age, place of residence and level of education, type of dental treatment used including services privately funded and reimbursed by the National Health Fund and the reasons of his/her decisions. In the second step we compared the results of the survey to the average price of commercial and reimbursed procedures to verified a possible correlations between them. The research tool was a questionnaire survey by the author. The questionnaires were distributed among randomly selected kindergartens, schools, workplaces, senior clubs, social care homes and random passers-by in the streets. Average prices of dental procedures were based on price lists of 12 commercial offices and National Health Fund's contract conditions for the reimbursed services. CONCLUSION: Regardless of the age, Poles are far more likely to use private dental care. The level of education affects the form of financing of the dental treatment of children. There is a large disproportion between the revenues of private and public dental offices providing the same dental services.

Delta radiomics analysis of Magnetic Resonance guided radiotherapy imaging data can enable treatment response prediction in pancreatic cancer.

BACKGROUND: Magnetic Resonance Image guided Stereotactic body radiotherapy (MRgRT) is an emerging technology that is increasingly used in treatment of visceral cancers, such as pancreatic adenocarcinoma (PDAC). Given the variable response rates and short progression times of PDAC, there is an unmet clinical need for a method to assess early RT response that may allow better prescription personalization. We hypothesize that quantitative image feature analysis (radiomics) of the longitudinal MR scans acquired before and during MRgRT may be used to extract information related to early treatment response. METHODS: Histogram and texture radiomic features (n = 73) were extracted from the Gross Tumor Volume (GTV) in 0.35T MRgRT scans of 26 locally advanced and borderline resectable PDAC patients treated with 50 Gy RT in 5 fractions. Feature ratios between first (F1) and last (F5) fraction scan were correlated with progression free survival (PFS). Feature stability was assessed through region of interest (ROI) perturbation. RESULTS: Linear normalization of image intensity to median kidney value showed improved reproducibility of feature quantification. Histogram skewness change during treatment showed significant association with PFS (p = 0.005, HR = 2.75), offering a potential predictive biomarker of RT response. Stability analyses revealed a wide distribution of feature sensitivities to ROI delineation and was able to identify features that were robust to variability in contouring. CONCLUSIONS: This study presents a proof-of-concept for the use of quantitative image analysis in MRgRT for treatment response prediction and providing an analysis pipeline that can be utilized in future MRgRT radiomic studies.

Unusual formation of the musculocutaneous and median nerves: a case report refined by intraneural dissection and literature review.

This report presents a detailed anatomical investigation of an upper limb specimen showing an atypical formation of the musculocutaneous nerve (MCN) and median nerve (MN). The study was refined by intraneural dissection, which supplements earlier descriptions of similar anatomical variations and allows for revision of the accepted classification. The case described in this report was an incidental finding during routine dissection of a fixed isolated upper limb. Intraneural dissection revealed partial fusion between the MCN and aberrant bundles of the MN. Those aberrant bundles joined the main steam of the MN at the level at which the MCN branched off as an independent nerve. The procedure allowed the aberrant fibres of the MN to be differentiated from the MCN. The presence of separate bundles in a territory corresponding to the MCN was confirmed, although those bundles and the aberrant MN bundles were covered by a common epineurium. The aberrant MN bundles running within the MCN did not contribute to innervation of the forearm muscles. They rejoined the main nerve trunk in the arm. A comprehensive understanding of the diverse anatomical variations of the upper limb nerves could be crucial for the safety and success of surgical procedures, especially procedures for reconstructing the brachial plexus or its branches.

The possibility of modification and improvement of dental services in Poland for children and adolescents with special emphasis on orthodontic service.

AIM: World Dental Federation reveals that dental caries is one of the most common diseases in the world, and as much as 90% of the population is facing oral cavity problems. About 28% of teenagers aged 10 and 15 absolutely needs orthodontic treatment and about another third of this age group represents very serious cases. The aim of this study is to verify the authorial model which modifies and facilitates the system of dental services in Poland with a special emphasis on orthodontic service. MATERIAL AND METHODS: The research was carried out with the method of diagnostic survey through a survey questionnaire. For this study, 1159 people were questioned for the research. In order to check the reliance between the variables Pearson chi-square test and the test of the Highest Reliability were used. Average market prices and the "prices expected" by the Greater Poland Voivodship Department of National Healthcare System were used to price dental services. RESULTS: The research revealed that the highest percentage of people who used only private dental services is between 19 and 64 years of age and the lowest percentage is represented by the elderly, i.e. subjects over 65 years of age. As for the dental services offered by the National Health Fund, the highest percentage of patients are children and adolescents under 18 and the lowest percentage of patients is represented by people in the working age. The tendency towards private healthcare is in direct proportion to parents' increase in the level of education. The main reason why parents take their children to a private dentist is the long waiting time for the visit offered by the National Health Fund as well as better materials and equipment offered by private dentists. The costs connected with extending the basket of guaranteed services for children and youngsters are combined with the increase in National Health Fund expenditure reaching EUR 7,014,151. The lack of refunding dental services for patients aged 19-64 will generate savings reaching about EUR 34,756,765. CONCLUSION: The reduction of public funds allocated for dental treatment of patients aged 19-64 will generate savings which will satisfy the needs connected with the increase in the range of refunded orthodontic treatment with the use of orthodontic permanent braces for patients under 18 years of age. The solution suggested will only slightly affect people in the working age as they reveal a strong tendency for treatment financed with their private funds.

Determinants of day-night difference in blood pressure, a comparison with determinants of daytime and night-time blood pressure.

Blunted day-night difference in blood pressure (BP) is an independent cardiovascular risk factor, although there is limited information on determinants of diurnal variation in BP. We investigated determinants of day-night difference in systolic (SBP) and diastolic (DBP) BP and how these compared with determinants of daytime and night-time SBP and DBP. We analysed the association of mean daytime, mean night-time and mean day-night difference (defined as (mean daytime-mean night-time)/mean daytime) in SBP and DBP with clinical, lifestyle and biochemical parameters from 1562 adult individuals (mean age 38.6) from 509 nuclear families recruited in the GRAPHIC Study. We estimated the heritability of the various BP phenotypes. In multivariate analysis, there were significant associations of age, sex, markers of adiposity (body mass index and waist-hip ratio), plasma lipids (total and low-density lipoprotein cholesterol and triglycerides), serum uric acid, alcohol intake and current smoking status on daytime or night-time SBP and/or DBP. Of these, only age (P=4.7 × 10-5), total cholesterol (P=0.002), plasma triglycerides (P=0.006) and current smoking (P=3.8 × 10-9) associated with day-night difference in SBP, and age (P=0.001), plasma triglyceride (P=2.2 × 10-5) and current smoking (3.8 × 10-4) associated with day-night difference in DBP. 24-h, daytime and night-time SBP and DBP showed substantial heritability (ranging from 18-43%). In contrast day-night difference in SBP showed a lower heritability (13%) while heritability of day-night difference in DBP was not significant. These data suggest that specific clinical, lifestyle and biochemical factors contribute to inter-individual variation in daytime, night-time and day-night differences in SBP and DBP. Variation in day-night differences in BP is largely non-genetic.

Screening for non-adherence to antihypertensive treatment as a part of the diagnostic pathway to renal denervation.

Renal denervation is a potential therapeutic option for resistant hypertension. A thorough clinical assessment to exclude reversible/spurious causes of resistance to antihypertensive therapy is required prior to this procedure. The extent to which non-adherence to antihypertensive treatment contributes to apparent resistance to antihypertensive therapy in patients considered for renal denervation is not known. Patients (n=34) referred for renal denervation entered the evaluation pathway that included screening for adherence to antihypertensive treatment by high-performance liquid chromatography-tandem mass spectrometry-based urine analysis. Biochemical non-adherence to antihypertensive treatment was the most common cause of non-eligibility for renal denervation-23.5% of patients were either partially or completely non-adherent to prescribed antihypertensive treatment. About 5.9% of those referred for renal denervation had admitted non-adherence prior to performing the screening test. Suboptimal pharmacological treatment of hypertension and 'white-coat effect' accounted for apparently resistant hypertension in a further 17.7 and 5.9% of patients, respectively. Taken together, these three causes of pseudo-resistant hypertension accounted for 52.9% of patients referred for renal denervation. Only 14.7% of referred patients were ultimately deemed eligible for renal denervation. Without biochemical screening for therapeutic non-adherence, the eligibility rate for renal denervation would have been 38.2%. Non-adherence to antihypertensive treatment and other forms of therapeutic pseudo-resistance are by far the most common reason of 'resistant hypertension' in patients referred for renal denervation. We suggest that inclusion of biochemical screening for non-adherence to antihypertensive treatment may be helpful in evaluation of patients with 'resistant hypertension' prior to consideration of renal denervation.

Fatty foci within the heart and the accompanying changes in the coronary arteries diagnosed in electrocardiogram-gated multislice computed tomography of the heart.

BACKGROUND: The purpose of our study was to analyse the relationship between fatty foci within the heart and the accompanying changes in the coronary arteries supplying the relevant heart chambers in a large group of patients referred to multi-slice computed tomography with electrocardiogram-gating examinations (ECG-MSCT) for various clinical reasons. MATERIALS AND METHODS: The ECG-MSCT examinations of 1,830 consecutive patients were analysed. The examinations were performed using 8-row (1,015 patients) and 64-row (815 patients) MSCT, in pre- and postcontrast scanning. In the group of patients with fatty foci within the heart the concomitant changes in the coronary arteries were assessed. It was analysed: the type of changes in the arteries; the relationship between the locations of the fatty deposits and the occurrence and type of changes in the coronary arteries. RESULTS: In 200 (10.9%) subjects fatty foci within the heart (112 men; 88 women; mean age 57.8) were detected. The distribution of the fat was as follows: right ventricle (RV) - 32.5%, left ventricle (LV) - 22.0%, biventricular - 45.5%. One hundred and seventy-two patients had concomitant changes in the coronary arteries. In patients with normal coronary arteries, significantly more often fatty deposits were localised within RV. Fat was primarily located subendocardially in the LV in patients with atherosclerosis in the left anterior descending artery (p < 0.001), in the right coronary artery (RCA) (p = 0.003), and in the left circumflex artery (LCX) (p < 0.001). Subpericardial locations of fatty deposits in RV significantly correlated with RCA bridging (p < 0.02); the subpericardial location of fat in LV significantly correlated with LCX bridging (p = 0.001). CONCLUSIONS: Fatty replacement of the myocardium is common, occurring in up to 10% of diagnosed patients and the majority of this group had concomitant changes in the coronary arteries. However, in the group of patients without changes in the coronary arteries, the fatty deposits locate themselves significantly more frequently within the RV.

Relationship between BDNF expression in major striatal afferents, striatum morphology and motor behavior in the R6/2 mouse model of Huntington's disease.

Patients with Huntington's disease (HD) and transgenic mouse models of HD show neuronal loss in the striatum as a major feature, which contributes to cognitive and motor manifestations. Reduced expression of the neurotrophin brain-derived neurotrophic factor (BDNF) in striatal afferents may play a role in neuronal loss. How progressive loss of BDNF expression in different cortical or subcortical afferents contributes to striatal atrophy and behavioral dysfunction in HD is not known, and may best be determined in animal models. We compared age-dependent alterations of BDNF mRNA expression in major striatal afferents from the cerebral cortex, thalamus and midbrain in the R6/2 transgenic mouse model of HD. Corresponding changes in striatal morphology were quantified using unbiased stereology. Changes in motor behavior were measured using an open field, grip strength monitor, limb clasping and a rotarod apparatus. BDNF expression in cortical limbic and midbrain striatal afferents is reduced by age 4 weeks, prior to onset of motor abnormalities. BDNF expression in motor cortex and thalamic afferents is reduced by 6 weeks, coinciding with early motor dysfunction and reduced striatum volume. BDNF loss in afferents progresses until death at 13-15 weeks, correlating with progressive striatal neuronal loss and motor abnormalities. Mutant huntingtin protein expression in R6/2 mice results in progressive loss of BDNF in both cortical and subcortical striatal afferents. BDNF loss in limbic and dopaminergic striatal inputs may contribute to cognitive/psychiatric dysfunction in HD. Subsequent BDNF loss in cortical motor and thalamic afferents may accelerate striatal degeneration, resulting in progressive involuntary movements.

Association between anthropometric obesity measures and coronary artery disease: a cross-sectional survey of 16,657 subjects from 444 Polish cities.

BACKGROUND: Excessive body weight is known to cluster with cardiovascular (CV) risk factors, but it is not clear which anthropometric obesity measure provides best independent predictive value of coronary artery disease (CAD). METHODS AND RESULTS: We explored associations between CAD and four different obesity measures (body mass index (BMI), waist circumference, waist/height and waist/height(2)) in a cohort of 16 657 subjects (40.4% men; 20.8% CAD patients), recruited by 700 primary care physicians in 444 Polish cities. 42.8% of subjects were classified as overweight, 31.7% as obese and 39.8% had abdominal obesity. In univariate analyses all obesity measures correlated with CAD (p>0.001), but waist/height(2) was the strongest discriminator between CAD patients and controls. Age-adjusted and sex-adjusted analyses confirmed a graded increase in CAD risk across distributions of all four obesity measures-1 standard deviation (SD) increase in BMI, waist, waist/height and waist/height(2) increased the odds of CAD by 1.23, 1.24, 1.26 and 1.27, respectively (all p<0.001). In models fully adjusted for CV risk factors, waist/height(2) remained the strongest obesity correlate of CAD, being the only independent associate of CAD in men. In a fully adjusted BMI-waist circumference stratified model, sarcopenic obesity (waist > median, BMI < median) and simple obesity (waist and BMI > median) were the strongest independent associates of CAD in men (p = 0.008) and women (p>0.001), respectively. CONCLUSION: This cross-sectional study showed that waist/height(2) may potentially offer a slightly higher predictive value of CAD than BMI or waist circumference and revealed an apparent sexual dimorphism in correlations between obesity measures and CAD.

The pressure of finding human hypertension genes: new tools, old dilemmas.

Researchers in hypertension genetics feel like they are left behind again. It always seems that the 'other' complex diseases are ahead in the race. Evolving new technologies in the form of genome-wide arrays and 'omics' technologies mean that investigators can now potentially identify many novel disease factors in one large-scale experiment. Hypertension research now faces the challenge of where to go next after the first genome-wide association experiments failed to provide robust candidates. In this review, we contemplate the old dilemma of whether such genes may ever be found; however, we believe advancing technologies and plummeting costs of large-scale experiments will contribute to the identification of novel molecules that underlie essential hypertension.

Angle-corrected imaging transcranial doppler sonography versus imaging and nonimaging transcranial doppler sonography in children with sickle cell disease.

BACKGROUND AND PURPOSE: Nonimaging transcranial Doppler sonography (TCD) and imaging TCD (TCDI) are used for determination of the risk of stroke in children with sickle cell disease (SCD). The purpose was to compare angle-corrected, uncorrected TCDI, and TCD blood flow velocities in children with SCD. MATERIALS AND METHODS: A total of 37 children (mean age, 7.8 +/- 3.0 years) without intracranial arterial narrowing determined with MR angiography, were studied with use of TCD and TCDI at the same session. Depth of insonation and TCDI mean velocities with and without correction for the angle of insonation in the terminal internal carotid artery (ICA) and middle (MCA), anterior (ACA), and posterior (PCA) cerebral arteries were compared with TCD velocities with use of a paired t test. RESULTS: Two arteries were not found on TCDI compared with 15 not found on TCD. Average angle of insonation in the MCA, ACA, ICA, and PCA was 31 degrees , 44 degrees , 25 degrees , and 29 degrees , respectively. TCDI and TCD mean depth of insonation for all arteries did not differ significantly; however, individual differences varied substantially. TCDI velocities were significantly lower than TCD velocities, respectively, for the right and left sides (mean +/- SD): MCA, 106 +/- 22 cm/s and 111 +/- 33 cm/s versus 130 +/- 19 cm/s and 134 +/- 26 cm/s; ICA, 90 +/- 14 cm/s and 98 +/- 27 cm/s versus 117 +/- 18 cm/s and 119 +/- 23 cm/s; ACA, 74 +/- 24 cm/s and 88 +/- 25 cm/s versus 105 +/- 23 cm/s and 105 +/- 31 cm/s; and PCA, 84 +/- 27 cm/s and 82 +/- 21 cm/s versus 95 +/- 23 cm/s and 94 +/- 20 cm/s. TCD and angle-corrected TCDI velocities were not statistically different except for higher angle-corrected TCDI values in the left ACA and right PCA. CONCLUSION: TCD velocities are significantly higher than TCDI velocities but are not different from the angle-corrected TCDI velocities. TCDI identifies the major intracranial arteries more effectively than TCD.

Glomerular hyperfiltration: a new marker of metabolic risk.

Chronic kidney disease coexists with metabolic syndrome and this relationship may be apparent before overt manifestations of cardiovascular disease. To investigate early stages of the natural history of associations between renal function and metabolic syndrome, we phenotyped 1572 young (mean age=18.4 years), apparently healthy men for metabolic risk factors and estimated their creatinine clearance based on the Cockcroft-Gault equation. High metabolic risk (clustering of at least three metabolic risk factors) was revealed in 8.7% (137) of the subjects and was associated with a 6.9-fold increase in the odds of glomerular hyperfiltration (95% confidence interval (CI): 3.9-11.5) when compared to reference (from none to two metabolic risk factors). Overweight, elevated blood pressure, and low high-density lipoprotein (HDL) cholesterol increased the multivariate-adjusted odds ratio of glomerular hyperfiltration to 6.6 (95% CI: 3.8-11.6), 1.8 (95% CI: 1.0-3.0), and 2.5 (95% CI: 1.5-4.3), respectively. Systolic and diastolic blood pressures clustered together with leptin in the factor analysis and this blood pressure-adiposity component correlated with estimated creatinine clearance (r=0.329, P<0.0001) and explained on its own 10.2% of the variance in the estimated renal function. Our data reveal the silent epidemics of metabolic risk among young, apparently healthy men. Furthermore, the results indicate that high metabolic risk is associated with glomerular hyperfiltration before overt manifestations of cardiovascular disease.

The impact of cooling ponds in North Central Texas on dairy farm performance.

The objective of this study was to determine whether measurable differences existed between farms with and without cooling ponds. Data from Dairy Herd Improvement records for 1999 through 2002 were obtained on 42 herds located in North Central Texas. Nineteen herds had installed cooling ponds, whereas 23 herds had not. Monthly somatic cell counts for each herd were obtained from the Federal Milk Market Administrator. Data were analyzed using the PROC MIXED regression model of SAS. Within and across herd groups, milk production from June to October was significantly lower compared with milk production for the rest of the year. Although there was numerically higher average milk production per cow per day throughout the year for herds that used cooling ponds, differences between herd groups that used or did not use cooling ponds were significant only for August production. Herds without a cooling pond had 4.8 kg/d per cow lower production in August than in the cool-season months of November to May (26.4 +/- 0.6 vs. 31.2 +/- 0.5 kg/d), whereas the difference in August production was only 2.9 kg/d per cow in herds that used cooling ponds (29.0 +/- 0.7 vs. 31.9 +/- 0.6 kg/d). Differences caused by seasonal use of a cooling pond in culling, days to first service, days open, percentage of estruses observed, and somatic cell counts were not significant. Bulk tank milk samples cultured for 10 different bacteria showed no difference between cooling pond and noncooling pond herds in 2002. Also, there was no difference in incidence of violations from the Texas Department of Health for herds that used or did not use cooling ponds. However, herds with cooling ponds did have a lower percentage of successful breedings, fewer days dry, and a higher percentage of cows in milk compared with dairy herds that used other forms of cooling. Such differences may or may not be attributed to seasonal use of a cooling pond. Therefore, cooling ponds may provide relief from heat stress without adversely affecting most important measures of herd performance.

Assessment of variability of renal blood flow Doppler parameters during the menstrual cycle in women.

OBJECTIVE: To estimate variability of renal flow Doppler parameters during the menstrual cycle in young women, and to explore whether the parameters oscillate substantially throughout the cycle. METHODS: The peak systolic, mean, and end-diastolic velocities, pulsatility (PI) and resistance (RI) indices, acceleration time (AT) and index (AI) of the right renal artery were measured nine times during the cycle with duplex sonography in 14 healthy women (age range, 23-25 years), and correlated with plasma concentrations of 17beta-estradiol and progesterone. Coefficient of variation (CV), interclass correlation (rho), and repeatability coefficients (RC) were used to measure the variability. RESULTS: The measures of the variability for AI and AT were: CV = 45.4% and 37.3%; rho = 0.25 and 0.15; RC = 10.1 and 99.5, respectively. The CV for flow velocities varied from 24.1% to 25.5%, rho from 0.49 to 0.50, RC from 22.7 for end-diastolic to 63.3 for peak systolic velocity. The respective figures for PI and RI were: CV = 17% and 8.3%; rho = 0.21 and 0.29; RC = 0.53 and 0.15. Fluctuations of the flow parameters, hematocrit, hemoglobin, heart rate, and systolic blood pressure during the menstrual cycle were insignificant, while the diastolic blood pressure decreased by about 7 mmHg (P < 0.01) in the luteal phase. CONCLUSION: The variability of renal flow Doppler parameters during the menstrual cycle in young healthy women is substantial. However, fluctuations of the values of the parameters throughout the cycle were non-significant.

Renal affection in patients with diabetes mellitus is not always caused by diabetic nephropathy.

Accumulated clinical data suggest that non-diabetic nephropathy complicating type 1 diabetes mellitus is rare, accounting for 2-3% of unselected diabetic patients with proteinuria. In contrast, non-diabetic kidney disease is a common finding in patients with type 2 diabetes mellitus. Joint analysis of available data on prevalence of non-diabetic kidney disease among type 2 diabetic patients revealed that non-diabetic nephropathy was evident on kidney biopsy approximately in 22% of European and 26.7% of Asian patients with type 2 diabetes mellitus. Therefore, kidney biopsy may become a useful diagnostic option among proteinuric patients with type 2 diabetes mellitus. However, it is generally agreed that renal biopsy cannot be used as a routine diagnostic test in all type 2 diabetic patients with proteinuria. Diabetic subjects that may benefit form kidney biopsy should be rather identified on a case-by-case basis. Absence of diabetic retinopathy, particularly used in combination with acanthocyturia, may come useful in decisions about kidney biopsy in type 2 diabetic patients.

Testosterone undecanoate: a useful tool for testosterone administration in rats.

A major obstacle of testosterone (T) treatment in experimental animals is the difficulty of maintaining long-term physiologic/anabolic steady serum levels after exogenous T administration. In two complementary studies we investigated the pharmacokinetic properties of different T formulations in male rats. Study I. Mature male Wistar rats (> 380 g, n = 4 - 7/group) were divided into four treatment groups: (1) sham-operated non orchiectomised (non-ORX) and placebo; (2) orchiectomised (ORX) and subcutaneous testosterone pellets (TP) (15, 25, 75 mg/60 days release or placebo pellets); (3) ORX and a single injection of testosterone undecanoate (TUD) (31, 62.5 or 125 mg/kg body weight subcutaneously (s.c.) or vehicle; (4) ORX and testosterone propionate (Tprop) (10, 20, 40 mg/month) or vehicle as a single injection s.c. Serum T was measured at baseline and in weekly intervals for 4 weeks. Study II. Mature male Wistar rats (180 - 200 g) were randomly assigned to one of 5 experimental groups (n = 5 - 6/group): (1) normal untreated rats (controls); (2) ORX untreated rats, and non-ORX rats receiving one of three treatment options; (3) 250 mg/kg body weight TUD i.m. (TUD 250); (4) 500 mg/kg body weight TUD i.m. (TUD 500); (5) 100-mg testosterone pellet/90 days release s.c. (TP 100). Serum T was measured at baseline and in intervals for 6 weeks after T administration. In both studies, the kinetic profile of TUD showed favourable continuous steady state levels over several weeks. In contrast, testosterone release by subcutaneous pellets resulted in a shorter than expected duration of elevated serum T levels with high inter-individual variability. Tprop administration led to only a short-lasting serum T increase with low serum T levels already 14 days after injection. In conclusion, a single injection of TUD (100 mg/kg body weight s.c.) is effective in inducing physiological testosterone levels in ORX rats for a minimum of four weeks. High dose TUD (500 mg/kg body weight i.m.) given as a single injection results in supraphysiological anabolic testosterone concentrations for up to six weeks in non-ORX rats. TUD was superior to other T release preparations and represents a convenient and effective tool for T administration in experimental animals.