Simultaneous production of polyhydroxyalkanoates and rhamnolipids by Pseudomonas aeruginosa

The feasibility of the simultaneous production of polyhydroxyalkanoates (PHAs) and rhamnolipids, as a novel approach to reduce their production costs, was demonstrated by the cultivation of Pseudomonas aeruginosa IFO3924. Fairly large amounts of PHAs and rhamnolipids were obtained from the bacterial cells and the culture supernatant, respectively. Decanoate was a more suitable carbon source than ethanol and glucose for the simultaneous production, although glucose was suitable for cell growth without an induction period under pH control. The kind of carbon source affected PHA monomer composition markedly and PHA molecular weight slightly. Monorhamnolipids and dirhamnolipids were included in the rhamnolipids extracted from the culture supernatant using decanoate, glucose, or ethanol as the carbon source. Both PHAs and rhamnolipids were synthesized after the growth phase. PHA content in the cell reached a maximum when the carbon source was exhausted. After exhaustion of the carbon source, PHA content decreased rapidly, but rhamnolipid synthesis, which followed PHA synthesis, continued. This resulted in a time lag for the attainment of maximum levels of PHAs and rhamnolipids. The reusability of the cells used in rhamnolipid production was evaluated in the repeated batch culture of P. aeruginosa IFO3924 for the simultaneous production of PHAs and rhamnolipids. High concentrations of rhamnolipids in the culture supernatant were attained at the end of both the first and second batch cultures. High PHA content was achieved in the resting cells that were finally harvested after the second batch. Simultaneous production of PHAs and rhamnolipids will enhance the availability of valuable biocatalysts of bacterial cells, and dispel the common belief that the production cost of PHAs accumulated intracellularly is almost impossible to become lower than that of cells themselves.     

pH-imprinted lipase catalyzed synthesis of dextran fatty acid ester

The application of enzymatic catalysis for the synthesis of polysaccharide-based surfactants was investigated. The polysaccharide dextran, a neutral bacterial polysaccharide consisting of -1,6 linked glucose units, was chemically modified by the attachment of hydrophobic groups through a transesterification reaction with a vinyl decanoate. A screening of commercially available lipases and protease for the synthesis of amphiphilic polysaccharides in DMSO suggested that lipase AY from Candida rugosa modified dextran T-40 with vinyl decanoate at the highest conversion. A pH-adjustment in a phosphate buffer at pH 7.5 prior to use is crucial to make this enzyme active in DMSO. The effect of enzyme concentration and mole ratio of fatty ester to dextran T-40 on the conversion and the rate of reaction were studied. Finally, investigation of the kinetics and regioselectivity of lipase AY-catalyzed modification offer a possibility to regulate the position and the extent of hydrophobic group attached to dextran. These two properties are fundamental for controlling the physico-chemical properties of the final polymeric surfactants.     

Amphetamine-induced aggression is enhanced in rats pre-treated with the anabolic androgenic steroid nandrolone decanoate

Aggression is one of the most commonly reported psychiatric side effects among anabolic-androgenic steroids (AAS) users. Furthermore, anecdotal stories say the aggression is even more profound when a current, or former, AAS-user consumes other drugs of abuse such as amphetamine and alcohol. In the present study, we examined the effect of amphetamine on defensive reactivity and defensive aggression in Sprague-Dawley rats after chronic AAS treatment (daily intramuscular [i.m.] injections with 15 mg/kg nandrolone decanoate [ND] for 14 days). Defensive reactions in rodents occur in response to a real threat, but also to perceived provocation, for example, elicited by innocuous stimuli as reaction towards the experimenter. The defensive reactivity and aggression test employed in this study evaluates each rat's reaction towards four different stimuli (I: approach of a rod; II: startle to an air puff; III: poking with a rod at the flanks, and IV: capturing with a gloved hand) at two different occasions. Immediately following the ND treatment period, no change in the defensive response was found. Nevertheless, an amphetamine challenge given 3 weeks after the last ND or vehicle injection induced a marked increased defensive aggressive response in the ND, compared to vehicle-pre-treated rats. Both ND- and vehicle-pre-treated rats receiving amphetamine were found to be more aggressive than comparable groups receiving a saline injection. It can be concluded that pre-treatment with ND modulates the behavioral response to amphetamine and induces long lasting changes in the behavioral response.     

The impact of nandrolone decanoate administration on ovarian and uterine tissues in rat: Luteinizing hormone profile,histopathological and morphometric assessment

The study had been conducted to evaluate the effects of nandrolone decanoate (abused repeated doses) on female rat’s ovary and uterus during administration and withdrawal. The study included 18 rats that were divided into control group (n = 6) and treated group (n = 12). The treated group was injected intramuscular (IM) with nandrolone decanoate (7 mg/kg body weight) for three consecutive days, for two weeks. The study stated that nandrolone decanoate increases the weights of body, ovary, and uterus. Moreover, it has a tendency of bringing upon modifications in the biochemical, histopathological, and morphological makeup of the female reproductive aspects. In conclusion, nandrolone decanoate has been identified as deleterious element for the female rats, and it is suggested that keen observations must be made on the human abusers to control and manage the possible pathologies.     

Dose‐Dependent Effects and Reversibility of the Injuries Caused by Nandrolone Decanoate in Uterine Tissue and Fertility of Rats

This study is the first to investigate the effects of different doses of nandrolone decanoate (ND) upon uterine tissue and fertility, and if the reproductive alterations can be restored after cessation of the treatment. Wistar female rats were treated with ND at doses of 1.87, 3.75, 7.5, and 15 mg/kg body weight, diluted in vehicle (n = 30/group), or received only mineral oil (control group, n = 45). The animals were divided into three periods of study: ND‐treated receiving a daily subcutaneous injection for 15 consecutive days (1), and treatment with ND followed by 30‐day recovery (2), and 60‐day recovery (3). At the end of each period, five females per group were induced to death to histopathological analysis and the others were allowed to fertility evaluation (at 19th gestational day). Animals that received ND followed by 30‐day recovery exhibited persistent diestrous and marked suppression of reproductive capacity. Conversely, after 60‐day recovery, only lowest doses females (1.87 and 3.75 mg/kg) exhibited restoration of normal estrous cyclicity. Uterine weights were increased after ND treatment similarly to that of the controls after 60‐day recovery. The ND‐treated groups showed histopathological changes in the endometrium, myometrium, and perimetrium, and an increase in the thickness of both muscular and serous layers. Notably, the recovery of uterine tissue after ND treatment was dose‐ and period‐dependent. We reported that administration of ND promoted damage in uterine tissue and fertility of rats, and the recovery periods were insufficient to restore all of the side effects caused by ND under a dose‐dependent response     

Anabolic-androgenic steroid does not enhance compensatory muscle hypertrophy but significantly diminish muscle damages in the rat surgical ablation model

Cellular responses in the compensatory hypertrophied (plantaris) muscle induced by surgical ablation of synergistic muscles (soleus and gastrocnemius) were determined during 10-week anabolic androgenic steroid (AAS) treatment. Adult Wistar male rats were divided randomly into the Control and Steroid groups, and contralateral surgery was performed. Nandrolone decanoate was administered to the Steroid group. [³H]thymidine and [¹⁴C]leucine labeling were used to determine the serial changes in cellular mitotic activity and amino acid uptake. Myogenic cells and cellular responses in blood vessels and nerve fibers were analyzed by immunohistochemistry. Significantly lower cellular mitotic activity associated with lower volume of muscle fiber necrosis was observed in the Steroid group during the first week. However, amino acid uptake and final muscle wet weight gain did not differ between the groups. Marked activation/proliferation of muscular, vascular, and peripheral nerve-related cells was seen with the inflammatory responses in both groups. However, this activation was dependent on the volume of muscle fiber damage and was not preferentially accelerated by AAS loading. These results indicated that AAS loading significantly diminished muscle fiber damages, but they did not accelerate final muscle wet weight gain and activation of myogenic, vascular, and peripheral nerve related cells in the compensatory enlarged muscles.     

Nandrolone decanoate interferes with testosterone biosynthesis altering blood–testis barrier components

The aim of this study was to investigate whether nandrolone decanoate (ND) use affects testosterone production and testicular morphology in a model of trained and sedentary mice. A group of mice underwent endurance training while another set led a sedentary lifestyle and were freely mobile within cages. All experimental groups were treated with either ND or peanut oil at different doses for 6 weeks. Testosterone serum levels were measured via liquid chromatography–mass spectrometry. Western blot analysis and quantitative real‐time PCR were utilized to determine gene and protein expression levels of the primary enzymes implicated in testosterone biosynthesis and gene expression levels of the blood–testis barrier (BTB) components. Immunohistochemistry and immunofluorescence were conducted for testicular morphological evaluation. The study demonstrated that moderate to high doses of ND induced a diminished serum testosterone level and altered the expression level of the key steroidogenic enzymes involved in testosterone biosynthesis. At the morphological level, ND induced degradation of the BTB by targeting the tight junction protein‐1 (TJP1). ND stimulation deregulated metalloproteinase‐9, metalloproteinase‐2 (MMP‐2) and the tissue inhibitor of MMP‐2. Moreover, ND administration resulted in a mislocalization of mucin‐1. In conclusion, ND abuse induces a decline in testosterone production that is unable to regulate the internalization and redistribution of TJP1 and may induce the deregulation of other BTB constituents via the inhibition of MMP‐2. ND may well be considered as both a potential inducer of male infertility and a potential risk factor to a low endogenous bioavailable testosterone.     

Physical provocation potentiates aggression in male rats receiving anabolic androgenic steroids

Anabolic androgenic steroids (AAS) have been linked to indiscriminant and unprovoked aggression and violence. We employed a brief tail pinch to examine the effects of different AAS on intermale aggression in gonadally intact male rats in response to a mild physical provocation. Animals received 5 mg/kg testosterone propionate (TP), nandrolone (ND), or stanozolol (ST) 5 days/week. Controls received vehicle injections. After 12 weeks, rats were tested for aggression while treatments continued. Animals were paired with either gonadally intact or castrated opponents and were tested in the subject rat's home cage, the opponents's home cage, and a neutral cage. Aggression was tested during tail pinch of the subject rat and during tail pinch of the opponent rat. In TP-treated males, tail pinch significantly enhanced aggression in all social and environmental conditions compared to intact controls. TP treatment also significantly enhanced aggression when the opponents were tail pinched. Tail pinch did not increase aggression in ND-treated males, and aggression was significantly lower than controls in ST-treated males. As expected, cell nuclear androgen receptor binding was significantly elevated by the high dose of TP. Our results show that while AAS alone does not induce the indiscriminate and unprovoked aggression characteristic of 'roid rage, TP heightens the animals sensitivity to     

费氏中华根瘤菌合成羟基丁酸和羟基己酸共聚体的研究

进行了费氏中华根瘤菌(Sinorhizobium fredii)合成羟基丁酸和羟基己酸共聚体[P(HB-HH)]的研究,通过摇瓶正交试验优化了培养基成分、培养条件和癸酸盐调控条件,采用发酵罐分批发酵和两阶段补料分批发酵方式及两步加盐法研究了P(HB-HH)的高密度发酵技术参数。经55h发酵,P(HB-HH)产量可以达到17.55g/L,其中HH单体含量占共聚体的20.6%,该共聚体的分子量约为1.4×105D。结果表明S.fredii的生产性状优良,有可能通过该菌株的高密度发酵与代谢调控实现P(HB-HH)的工业化生产。