Effects of Panax ginseng on the nerve growth factor expression in testosterone induced benign prostatic hyperplasia

The prostatic hyperplasia in benign prostatic hyperplasia (BPH) leads to obstructive micturition symptoms. Previous studies showed that pontine micturition center (PMC), ventrolateral periaqueductal gray (vlPAG), and medial preopticnucleus (MPA) regions in the brain have been known to regulate the urinary bladder function. The present study shows the influences of Panax ginseng on nerve growth factor (NGF) expressions in PMC, vlPAG, and MPA regions in the brain. Wistar rats were used for the present study. The rats split into four groups; 4 groups (n = 6) in control group, BPH-induced group, BPH-induced and P. ginseng-treated group, and BPH-induced and finasteride-treated group. BPH in rats was induced by testosterone and the animals were evaluated for NGF expression in PMC, vlPAG, and MPA regions in the brain. The NGF expression was identified using immunohistochemistry (IHC). The NGF expression by IHC showed spots with dark brown color. In our results, NGF expressions in PMC, vlPAG, and MPA regions in the brainstem of the BPH-induced group showed increase than the control animal. These increased NGF expressions in three regions were decreased using treatment with P. ginseng (200 mg/kg). These results suggest that P. ginseng has therapeutic effects on the symptoms of BPH and is associated with the regulation of NGF expression in the brain. In conclusion, the administration of P. ginseng helps nerve growth factor activation.     

The anti-inflammatory properties of the methanolic extract of Cucumis melo Linn. against prostate enlargement in Wistar rats

In different parts of the world, Cucumis melo Linn. (C melo) is used for its medicinal properties. The present study examined the effects of a methanolic extract of C melo Linn. (F1 hybrid, MECM) on benign prostatic hyperplasia in adult male Wistar rats and evaluated its anti-inflammatory activity in vivo. MECM treatment reduced prostate weight mildly. Histopathological studies showed that the extract produced a strong protective effect against the development of BPH by testosterone. The MECM also showed protection from testosterone-induced benign prostatic hyperplasia (BPH). MECM was tested against carrageenan-induced inflammation in rats' paws to determine its anti-inflammatory activity. It was shown that MECM had a pronounced effect on the inflammatory response in the late phase, i.e., one hour after carrageenan injection. Prostaglandins and nitric oxide are primarily responsible for this phase indicating that MECM can modify the production and release of prostaglandin and nitric oxide. A novel formulation containing C melo may be able to treat the conditions mentioned above.     

A phytosterol enriched refined extract of Brassica campestris L. pollen significantly improves benign prostatic hyperplasia (BPH) in a rat model as compared to the classical TCM pollen preparation Qianlie Kang Pule’an Tablets

In Qinghai Province, the Brassica campestris L. pollen preparation Qianlie Kang Pule’an Tablet (QKPT) is traditionally used for BPH therapy. However, in QKPT the content of supposedly active phytosterols is relatively low at 2.59%, necessitating high doses for successful therapy. Therefore, a phytosterol enriched (4.54%) refined extract of B. campestris pollen (PE) was developed and compared with QKPT in a BPH rat model. Six groups of rats (n = 8 each), namely sham-operated distilled water control, castrated distilled water control, castrated QKPT 2.0 g/kg, castrated PE 0.1 g/kg, castrated PE 0.2 g/kg, and castrated PE 0.4 g/kg, were intragastrically treated with the respective daily doses. Testosterone propionate (0.3 mg/day) was administered to all castrated rats, while the sham-operated group received placebo injections. After 30 days, the animals were sacrificed and prostates as well as seminal vesicles excised and weighted in order to calculate prostate volume index (PVI) as well as prostate index (PI) and seminal vesicle index (SVI), defined as organ weight in g per 100 g body weight. Compared with sham-operated controls, PI (p < 0.01), PVI (p < 0.01), and SVI (p < 0.01) were all significantly increased in all castrated, testosterone treated rats. After treatment with PE at 0.4 and 0.2 g/kg or QKPT at 2.0 g/kg per day, both indices were significantly reduced (p < 0.01) as compared to the castrated distilled water control. For PE at 0.1 g/kg per day only PI was significantly reduced (p < 0.05). At the highest PE concentration of 0.4 g/kg per day both PI and SVI were also significantly reduced when compared to the QKPT group (p < 0.05). Both PE and QKPT demonstrated curative effects against BPH in the applied animal model. In its highest dose at 0.4 g/kg per day, PE was clearly superior to QKPT.     

Use of selenium–silymarin mix reduces lower urinary tract symptoms and prostate specific antigen in men

The aim of this double-blind, placebo controlled clinical trial was to assess the effects of a combination of selenium and silymarin in men with lower urinary tract symptoms, benign prostatic hyperplasia and a prostate specific antigen (PSA) ≤2.5 ng/ml. The volunteers were randomized to two groups: the first one (n = 26) received 240 μg selenium (in the form of yeast l-selenomethionine) plus 570 mg silymarin daily for 6 months and the second (n = 29) received placebo. Outcome measures were changes in the International Prostate Symptom Score (IPSS), bladder volume (V), urinary flow rate, ultrasound estimated postvoid residual urine volume (RV), serum PSA, testosterone and selenium levels, safety clinical biochemistry, hematology and oxidative stress parameters at baseline and on day 180. The results showed statistically significant differences (p < 0.05) between treatment and control groups for the following parameters: IPSS score, urodynamic parameters: maximal rate of urine flow (Q_max), average flow (Q_ave), V and RV, total PSA value and serum selenium levels. There was a significant reduction in PSA in the selenium–silymarin group but no effect on blood testosterone level. Overall the treatment was well-tolerated with no adverse effects.     

Isolation,identification of sludge-lysing strain and its utilization in thermophilic aerobic digestion for waste activated sludge

A strain of sludge-lysing bacteria was isolated from waste activated sludge (WAS) in this study. The result of 16S rRNA gene analysis demonstrated that it was a species of new genus Brevibacillus (named Brevibacillus sp. KH3). The strain could release the protease with molecule weight of about 40 kDa which could enhance the efficiency of sludge thermophilic aerobic digestion. During the sterilized sludge digestion experiment inoculated with Brevibacillus sp. KH3, the maximum protease activity was 0.41 U/ml at pH 8 and 50 °C, and maximum TSS removal ratio achieved 32.8% after 120 h digestion at pH 8 and 50 °C. In the case of un-sterilized sludge digestion inoculated with Brevibacillus sp. KH3, TSS removal ratio in inoculated-group was 54.8%, increasing at 11.86% compared with un-inoculation (46.2%). The result demonstrated that inoculation of Brevibacillus sp. KH3 could help to degrade the EPS and promote the collapse of cells and inhibit the growth of certain kinds of microorganisms. It indicated that Brevibacillus sp. KH3 strain had a high potential to enhance WAS-degradation efficiency in thermophilic aerobic digestion.     

Prenatal androgen exposure and children's aggressive behavior and activity level

Some human behaviors, including aggression and activity level, differ on average for males and females. Here we report findings from two studies investigating possible relations between prenatal androgen and children's aggression and activity level. For study 1, aggression and activity level scores for 43 girls and 38 boys, aged 4 to 11 years, with congenital adrenal hyperplasia (CAH, a genetic condition causing increased adrenal androgen production beginning prenatally) were compared to those of similarly-aged, unaffected relatives (41 girls, 31 boys). Girls with CAH scored higher on aggression than unaffected girls, d = 0.69, and unaffected boys scored higher on activity level than unaffected girls, d = 0.50. No other group differences were significant. For study 2, the relationship of amniotic fluid testosterone to aggression and activity level was investigated in typically-developing children (48 girls, 44 boys), aged 3 to 5 years. Boys scored higher than girls on aggression, d = 0.41, and activity level, d = 0.50. However, amniotic fluid testosterone was not a significant predictor of aggression or activity level for either sex. The results of the two studies provide some support for an influence of prenatal androgen exposure on children's aggressive behavior, but not activity level. The within-sex variation in amniotic fluid testosterone may not be sufficient to allow reliable assessment of relations to aggression or activity level.     

MGMT Ile143Val polymorphism,dietary factors and the risk of breast,colorectal and prostate cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk study

O⁶-Methylguanine-DNA methyltransferase (MGMT) repairs DNA damage caused by alkylating agents including N-nitroso compounds from diet. MGMT Ile143Val polymorphism may lead to less DNA damage repair and increased cancer risk depending on the environmental exposures. We investigated interactions between dietary factors and the MGMT Ile143Val polymorphism in relation to breast, colorectal and prostate cancer risk. There were 276/1498, 273/2984 and 312/1486 cases/controls for the breast, colorectal and prostate cancer studies respectively; all nested within the EPIC-Norfolk study, a prospective cohort of approximately 25,000 men and women aged 40–79. Baseline 7-day food diary data were collected for dietary assessment. MGMT Ile143Val polymorphism was not overall associated with breast, colorectal and prostate cancer risk. There was a significant interaction between this polymorphism and intake of red and processed meat on colorectal cancer risk (P_interaction = 0.04) suggesting an increased risk among carriers of the variant genotype compared to the MGMT Ile143Ile common genotype. A lower colorectal cancer risk was seen with higher intake of vitamin E and carotene among the variant genotype group but not in the common genotype group (P_interaction = 0.009 and P_interaction = 0.005 for vitamin E and carotene, respectively). A higher prostate cancer risk was seen with higher alcohol intake among the variant genotype (OR = 2.08, 95% CI = 1.21–3.57, P_interaction = 0.0009) compared to the common genotype with lower alcohol intake. In this UK population, the MGMT Ile143Val polymorphism was not overall associated with breast, colorectal and prostate cancer risk. There was evidence for this polymorphism playing a role in modulating the risk of prostate cancer in presence of alcohol. For colorectal cancer, the MGMT Ile143Val polymorphism may confer increased or decreased risk depending on the dietary exposure.     

Male infertility: Decreased levels of selenium,zinc and antioxidants

In this study, we aimed to compare the level of zinc, selenium, glutathione peroxidase activity and antioxidant status in following populations of men: severe inflammation in prostate (>10⁶ white blood cells in prostate secretion; n = 29), severe leukocytospermia, (>10⁶ white blood cells in semen; n = 31), mild inflammation, (0.2–1 M white blood cells in semen or prostate secretion; n = 24), non-inflammatory oligozoospermia (n = 32) and healthy controls (n = 27). Male partners of infertile couples had reduced level of antioxidative activity, selenium and zinc in their seminal plasma. Most importantly, reduced selenium levels were evident in all patient groups regardless of inflammation status. Therefore, these patients might gain some benefit from selenium supplementation.     

Sexual performance of Awassi ram lambs reared in different sex composition groups

The objective of this study was to evaluate the effect of sex composition of the group of lambs before puberty on later sexual performance in Awassi ram lambs. Thirteen Awassi ram lambs of the same age were raised in either all-male group (n = 7) or in a group mixed with females (n = 6) from weaning to puberty. Blood samples, body weights (BW) and scrotal circumferences (SC) of ram lambs were recorded between eight and 10 months of age. Sexual performance testing was performed at 9 months of age by individually exposing ram lambs to oestrous females on five occasions. Body weight and SC were greater (P < 0.01) in the all-male compared with the mixed group. Plasma testosterone concentrations were not influenced (P > 0.05) by treatment. Plasma testosterone concentrations were significantly correlated (P ≤ 0.05) with BW (r = 0.3) and SC (r = 0.4). No treatment effects were detected regarding bouts of leg-kicking. Bouts of anogenital sniffing, the frequency of mount attempts and mounting frequency were greater (P < 0.05) in the all-male group. Even though the frequency of raising the fat tail of females was similar between the two treatments, the mixed group tended to be (P = 0.08) more efficient in doing so than the all-male group (higher tail raising/mount). Results of the current study indicate that mixing groups of ram and ewe lambs before puberty may be insufficient to improve later sexual performance of ram lambs.     

Comparative research of chemical constituents,antifungal and antitumor properties of ether extracts of Panax ginseng and its endophytic fungus

The chemical compositions and bioactivities of ether extracts of an endophytic fungus Paecilomyces sp. isolated from Panax ginseng were reported, and the comparative analysis of the constituents, antifungal and antitumor properties of the ether extracts from this fungus and its host ginseng were also conducted. By means of GC/MS technique, 51 compounds of Panax ginseng and 38 compounds of Paecilomyce sp. were determined. It is attractive that the extracts derived from Paecilomyce sp. and ginseng samples contained the same compound falcarinol, a natural pesticide and anti-cancer agent. The ether extracts of Paecilomyce sp., tested at 7.8 μg/ml, completely inhibited the visible growth of Pyricularia oryzae. Furthermore, both extracts were tested against four human pathogenic fungi and showed the IC₈₀ of Paecilomyce sp. was 4 μg/ml against Trichophyton rubrum, equally to the control. Finally, the in vitro antitumor experience showed that the most of the IC₅₀ values were all being below 20 μg/ml.     

The role of androst-5-ene-3β,17β-diol (androstenediol) in cell proliferation in endometrium of women with polycystic ovary syndrome

Women with polycystic ovary syndrome (PCOS) show high prevalence of endometrial hyperplasia and adenocarcinoma. Endometrial proliferation is increased, evaluated by high levels of Ki67 (cell cycle marker) and low levels of p27 (negative regulator of cell cycle). Nevertheless, endometrial changes in cyclin D1 (positive regulator of cell cycle) in PCOS-women are not described. Androst-5-ene-3β,17β-diol (androstenediol), steroid with estrogenic activity present in endometria, could be related to increased endometrial cell proliferation. The objective of this study was to determine protein content of cyclin D1 and androstenediol levels in endometria from PCOS and control-women and to evaluate the possible mechanism favoring cell proliferation associated with hormonal characteristics of patients. Therefore, cyclin D1 protein content in PCOS-women and control-endometrial tissue were assessed by western blot and immunohistochemistry. The androstenediol levels were evaluated by ELISA. To further analyze the effect of steroids (androstenediol, 17β-estradiol, testosterone) in cell proliferation, levels of proteins cyclin D1, p27 and Ki67 were evaluated in an in vitro model of stromal endometrial cells T-HESC and St-T1b. An increase in cyclin D1 and androstenediol was observed in tissues from PCOS-women relative to control group (p < 0.05). In the in vitro model, androstenediol exerted increase in cyclin D1 (p < 0.05) and a decrease in p27 protein level (p < 0.05), while Ki67 in St-T1b cells increased under this stimulus (p < 0.05). Testosterone produces opposite effects in the levels of the above markers (p < 0.05). Therefore, the hormonal imbalance associated with this syndrome could alter endometrial tissue homeostasis, promoting cell proliferation. Androstenediol is a molecule that could be involved by stimulating proliferation, whereas testosterone elicits a role of cell cycle repressor.     

Pathogenic role of HIF-1α in prostate hyperplasia in the presence of chronic inflammation

Benign prostatic hyperplasia (BPH) commonly occurs in older men with chronic prostatitis. Although BPH is frequently accompanied by inflammation, it is unclear whether inflammation underlies prostate enlargement. Recently, we reported that hypoxia‐inducible factor 1α (HIF-1α), which is known to be induced by proinflammatory cytokines, is involved in testosterone-induced prostate hyperplasia. Therefore, we hypothesized that cytokines secreted from infiltrated macrophages under inflammatory conditions stimulate prostate enlargement by up‐regulating HIF-1α. In the present study, we injected lipopolysaccharide (LPS) into rat prostates to mimic prostatitis and evaluated prostate hyperplasia 14 days later. Epithelial cells of LPS-treated prostates were found to be highly proliferative and HIF-1α levels in prostate tissues to be elevated. When prostate epithelial cells were incubated in conditioned medium from macrophages activated with LPS, they robustly expressed HIF-1α, and under these conditions IL-1β, IL-6, and TNF-α cytokines were found to mediate HIF-1α induction. In addition, HIF-1α was found to enhance the expression of Twist, which initiates epithelial–mesenchymal transition (EMT). Furthermore, profound EMT features were observed in LPS-treated rat prostates, and the natural HIF-1α inhibitors ascorbate and curcumin were found to attenuate EMT and prostate hyperplasia both in vivo and in vitro. Based on these results, we propose that HIF-1α mediates prostate enlargement under inflammatory conditions, and we suggest that HIF-1α be viewed as a promising target for blocking the transition from prostatitis to BPH.     

A higher prediagnostic insulin level is a prospective risk factor for incident prostate cancer

A higher insulin level has been linked to the risk of prostate cancer promotion. However, several reports claim that there is no association between a higher insulin level and the risk of incident prostate cancer. In the present report, the insulin hypothesis was tested once more prospectively in men with a benign prostatic disorder. Three hundred and eighty-nine consecutive patients referred with lower urinary tract symptoms without clinical prostate cancer were included during 1994–2002. Follow-up was performed in 2006. Data were obtained from the Swedish National Cancer Register and the Regional Cancer Register, Oncological Centre, Göteborg, Sweden. At this follow-up, 44 of the patients included had developed prostate cancer. Men with prostate cancer diagnosis had a higher systolic (P < 0.001) and diastolic blood pressure (P < 0.000), were more obese as measured by BMI (P = 0.010), waist (P = 0.007) and hip measurements (P = 0.041) than men who did not have prostate cancer diagnosis at follow-up. These men also had a higher uric acid level (P = 0.040), and a higher fasting serum insulin level (P = 0.023) than men who did not have prostate cancer diagnosis at follow-up. Following exclusion of T1a/b prostate cancer cases, the difference of the fasting serum insulin level between the groups was still significant (P = 0.038). Our data support the hypothesis that a higher insulin level is a promoter of prostate cancer. Moreover, our data suggest that the insulin level could be used as a marker of the risk of developing prostate cancer. The present findings also seem to confirm that prostate cancer is a component of the metabolic syndrome. Finally, our data generate the hypothesis that the metabolic syndrome conceals early prostate cancer.     

Effects of competition outcome on testosterone concentrations in humans: An updated meta-analysis

A contribution to a special issue on Hormones and Human Competition.Since Archer's (2006) influential meta-analysis, there has been a major increase in the number of studies investigating the effect of competition outcome on testosterone reactivity patterns in humans. Despite this increased research output, there remains debate as to whether competition outcome modulates testosterone concentrations. The present paper examines this question using a meta-analytic approach including papers published over the last 35 years. Moreover, it provides the first meta-analytic estimate of the effect of competition outcome on testosterone concentrations in women. Results from a meta-analysis involving 60 effect sizes and > 2500 participants indicated that winners of a competition demonstrated a larger increase in testosterone concentrations relative to losers (D = 0.20)—an effect that was highly heterogeneous. This ‘winner-loser’ effect was most robust in studies conducted outside the lab (e.g., in sport venues) (D = 0.43); for studies conducted in the lab, the effect of competition outcome on testosterone reactivity patterns was relatively weak (D = 0.08), and only found in studies of men (D = 0.15; in women: D = − 0.04). Further, the 'winner-loser' effect was stronger among studies in which pre-competition testosterone was sampled earlier than (D = 0.38, after trim and fill correction) rather than within (D = 0.09) 10 min of the start of the competition. Therefore, these results also provide important insight regarding study design and methodology, and will be a valuable resource for researchers conducting subsequent studies on the 'winner loser' effect.     

Relationship of Prostate -Specific Antigen to Age and Testosterone in Men With Type 2 Diabetes Mellitus

ObjectiveTo determine whether prostate-specific antigen (PSA) concentrations in type 2 diabetic men with hypogonadotrophic hypogonadism are lower than those in eugonadal men with type 2 diabetes and whether PSA concentrations are related to plasma testosterone concentrations.MethodsIn this cross-sectional study, we measured serum total testosterone, sex hormone–binding globulin, free testosterone, PSA, hematocrit, and hemoglobin A_1c in consecutive type 2 diabetic men who presented to 2 endocrinology referral centers between January 2006 and January 2007. We collected other clinical and demographic data including age, height, weight, and ethnicity.ResultsOf 400 eligible patients, 280 men met inclusion criteria. Plasma PSA concentrations were lower in type 2 diabetic men with low free testosterone concentrations than in those with normal free testosterone concentrations (25.65 ± 2.02 ng/dL vs 31.70 ± 2.31 ng/dL, P = .011). PSA concentrations were positively related to age (r = 0.34, P < .001), total testosterone (r = 0.29, P < .001), free testosterone (r = 0.17, P = .02), and sex hormone– binding globulin (r = 0.22, P < .001) and negatively related to body mass index (r = –0.28, P < .001). In stepwise backward regression analysis, PSA concentration was predicted by age (P < .001) and free testosterone (P < .001), but not by body mass index or sex hormone–binding globulin.ConclusionsPlasma PSA concentrations are lower in type 2 diabetic men with hypogonadism than in eugonadal men with type 2 diabetes, and plasma PSA is related to age, plasma total testosterone concentrations, and free testosterone concentrations in patients with type 2 diabetes. (Endocr Pract. 2008;14:1000-1005)     

Age-independent increases in male salivary testosterone during horticultural activity among Tsimane forager-farmers

Testosterone plays an important role in mediating male reproductive trade-offs in many vertebrate species, augmenting muscle and influencing behavior necessary for male–male competition and mating-effort. Among humans, testosterone may also play a key role in facilitating male provisioning of offspring as muscular and neuromuscular performance is deeply influenced by acute changes in testosterone. This study examines acute changes in salivary testosterone among 63 Tsimane men ranging in age from 16 to 80 (mean 38.2) years during one-hour bouts of tree-chopping while clearing horticultural plots. The Tsimane forager-horticulturalists living in the Bolivian Amazon experience high energy expenditure associated with food production, have high levels of parasites and pathogens, and display significantly lower baseline salivary testosterone than age-matched US males. Mixed-effects models controlling for BMI and time of specimen collection reveal increased salivary testosterone (p < 0.001) equivalent to a 48.6% rise, after one hour of tree chopping. Age had no effect on baseline (p = 0.656) or change in testosterone (p = 0.530); self-reported illness did not modify testosterone change (p = 0.488). A comparison of these results to the relative change in testosterone during a competitive soccer tournament in the same population reveals larger relative changes in testosterone following resource production (tree chopping), compared to competition (soccer). These findings highlight the importance of moving beyond a unidimensional focus on changes in testosterone and male–male aggression to investigate the importance of testosterone–behavior interactions across additional male fitness-related activities. Acutely increased testosterone during muscularly intensive horticultural food production may facilitate male productivity and provisioning.     

Combined effect of probiotics and specific immunoglobulin Y directed against Escherichia coli on growth performance,diarrhea incidence,and immune system in calves

Enterotoxigenic Escherichia coli (ETEC) K99 is one of the major pathogens associated with calf diarrhea. The induction of passive immunity in animals by immunoglobulin Y and using probiotics are inexpensive alternatives to antibiotics for the prevention and treatment of a number of bacterial infections, including diarrhea. Hence, the aim of this research was to evaluate the impact of dietary probiotics and ETEC K99-specific egg yolk antibody supplements, alone and in combination with each other, on health and growth parameters, diarrhea incidence and immune stimulation in newborn Holstein calves. One hundred and twenty neonatal calves were allocated randomly into 4 dietary groups (n = 30 per group) received colostrum/milk without any additives (control group), or supplemented with egg yolk powder contained E. coli K99-specific antibody (Ab group; 1 g/day), a commercial probiotic, Hypro-calves (Pro group; 3 g/day), and their combination (Ab + Pro group), from day (d) 1 to d28 of age. Analyses of the growth parameters, feed efficiency, fecal score, and microbiota and immune function were carried out on d0, 14, 21, and 28 of the experiment. Calves in Ab or Ab + Pro group had higher (P < 0.05) average daily gain compared to control and Pro groups during 0–14d. Feed efficiency of calves in Ab and Ab + Pro groups was significantly higher than that in control group during the period of 0–14d; however, no significant differences were observed in 0–28d period. Diarrhea prevalence and fecal score in Ab + Pro group were lower than control group (P < 0.05). Calves in Ab + Pro group had the lowest number of fecal E. coli in comparison to other groups on d28 (P < 0.05). Feeding Ab + Pro supplement increased (P < 0.05) concentrations of blood IgA and serum CD4 compared to the control group. Likewise, calves in Pro group had higher CD4 levels as compared to the control calves (P < 0.05). Serum concentration of interferon-gamma in control group was lower than other groups (P < 0.05). Overall, these data suggest that feeding a combination of probiotic and specific antibody against ETEC to neonate Holstein calves enhances feed efficiency, boosts immunity, and reduces diarrhea prevalence.     

Mixotrophy in the newly described dinoflagellate Yihiella yeosuensis: A small,fast dinoflagellate predator that grows mixotrophically,but not autotrophically

To investigate tropical roles of the newly described Yihiella yeosuensis (ca. 8 μm in cell size), one of the smallest phototrophic dinoflagellates in marine ecosystems, its trophic mode and the types of prey species that Y. yeosuensis can feed upon were explored. Growth and ingestion rates of Y. yeosuensis on its optimal prey, Pyramimonas sp. (Prasinophyceae), as a function of prey concentration were measured. Additionally, growth and ingestion rates of Y. yeosuensis on the other edible prey, Teleaulax sp. (Cryptophyceae), were also determined for a single prey concentration at which both these rates of Y. yeosuensis on Pyramimonas sp. were saturated. Among bacteria and diverse algal prey tested, Y. yeosuensis fed only on small Pyramimonas sp. and Teleaulax sp. (both cell sizes = 5.6 μm). With increasing mean prey concentrations, both specific growth and ingestion rates of Y. yeosuensis increased rapidly before saturating at a mean Pyramimonas concentration of 109 ng C mL⁻¹ (2725 cells mL⁻¹). The maximum growth rate (mixotrophic growth) of Y. yeosuensis fed with Pyramimonas sp. at 20 °C under a 14:10-h light-dark cycle of 20 μE m⁻² s⁻¹ was 1.32 d⁻¹, whereas the growth rate of Y. yeosuensis without added prey was 0.026 d⁻¹. The maximum ingestion rate of Y. yeosuensis fed with Pyramimonas sp. was 0.37 ng C predator⁻¹ d⁻¹ (9.3 cells predator⁻¹ d⁻¹). At a Teleaulax concentration of 1130 ng C mL⁻¹ (66,240 cells mL⁻¹), growth and ingestion rates of Y. yeosuensis fed with Teleaulax sp. were 1.285 d⁻¹ and 0.38 ng C predator⁻¹ d⁻¹ (22.4 cells predator⁻¹ d⁻¹), respectively. Thus, Y. yeosuensis rarely grows without mixotrophy, and mixotrophy supports high growth rates in Y. yeosuensis. Y. yeosuensis has the highest maximum mixotrophic growth rate with the exception of Ansanella graniferaamong engulfment feeding mixotrophic dinoflagellates. However, the high swimming speed of Y. yeosuensis (1572 μm s⁻¹), almost the highest among phototrophic dinoflagellates, may prevent autotrophic growth. This evidence suggests that Y. yeosuensis may be an effective mixotrophic dinoflagellate predator on Pyramimonas and Teleaulax, and occurs abundantly during or after blooms of these two prey species.     

Early testosterone replacement attenuates intracellular calcium dyshomeostasis in the heart of testosterone-deprived male rats

BackgroundTestosterone deficiency in elderly men increases the risk of cardiovascular disease. In bilateral orchiectomized (ORX) animals, impaired cardiac Ca²⁺ regulation was observed, and this impairment could be improved by testosterone replacement, indicating the important role of testosterone in cardiac Ca²⁺ regulation. However, the temporal changes of Ca²⁺ dyshomeostasis in testosterone-deprived conditions are unclear. Moreover, the effects of early vs. late testosterone replacement are unknown. We hypothesized that the longer the deprivation of testosterone, the greater the impairment of cardiac Ca²⁺ homeostasis, and that early testosterone replacement can effectively reduce this adverse effect.MethodsMale Wistar rats were randomly divided into twelve groups, four sets of three. The first set were ORX for 2, 4 and 8 weeks, the second set were sham-operated groups of the same periods, the third set were ORX for 8 weeks coupled with a subcutaneous injection of vehicle (control), testosterone during weeks 1–8 (early replacement) or testosterone during weeks 5–8 (late replacement), and finally the 12-week sham-operated, ORX and ORX treated with testosterone groups. Cardiac Ca²⁺ transients (n = 4-5/group), L-type calcium current (I_Ca-L) (n = 4/group), Ca²⁺ regulatory proteins (n = 6/group) and cardiac function (n = 5/group) were determined.ResultsIn the ORX rats, impaired cardiac Ca²⁺ transients and reduced I_Ca-L were observed initially 4 weeks after ORX as shown by decreased Ca²⁺ transient amplitude, rising rate and maximum and average decay rates. No alteration of Ca²⁺ regulatory proteins such as the L-type Ca²⁺ channels, ryanodine receptor type 2, Na⁺-Ca²⁺ exchangers and SERCA2a were observed. Early testosterone replacement markedly improved cardiac Ca²⁺ transients, whereas late testosterone replacement did not. The cardiac contractility was also improved after early testosterone replacement.ConclusionsImpaired cardiac Ca²⁺ homeostasis is time-dependent after testosterone deprivation. Early testosterone replacement improves cardiac Ca²⁺ transient regulation and contractility, suggesting the necessity of early intervention in conditions of testosterone-deprivation.