Microplastic and natural sediment in bed load saltation: Material does not dictate the fate.

Microplastic (MP) pollution is a well document threat to our aquatic and terrestrial ecosystems, however, the mechanisms by which MPs are transported in river flows are still unknown. The transport of MPs and natural sediment in aquatic flows could be somewhat comparable, as particles are similar in size. However, it is unknown how the lower density of MPs, their shape and their different material properties impact transport dynamics. To answer this, novel laboratory experiments on bed load saltation dynamics in an open-channel flow, using high-speed camera imaging and the detection of 11,035 individual saltation events were used to identify the similarities and differences between spherical MPs and spherical natural sediments transport. The tested MPs and sediment varied in terms of size and material properties (density and elasticity). Our analysis shows that the Rouse number accurately describes saltation length, height, transport velocity and collision angles equally well for both MPs and natural sediments. Through statistical inference, the distribution functions of saltation trajectory characteristics for MPs were analogous to natural sediment with only one sediment experiment (1.4% of cases) differing from all other plastic experiments. Similarly, only nine experiments (9.3% of cases) showed that collision angles for MPs differed from those of natural sediment experiments. Differences observed in terms of restitution become negligible in overall transport dynamics as turbulence overcomes the kinetic energy lost at particle-bed impact, which keeps particle motion independent from impact. Overall, spherical MP particles behave similarly to spherical natural sediments in aquatic environments under the examined experimental conditions. This is significant because there is an established body of knowledge for sediment transport that can serve as a foundation for the study of MP transport.

Microplastics in the riverine environment: Meta-analysis and quality criteria for developing robust field sampling procedures.

Current sampling approaches for quantifying microplastics (MP) in the riverine water column and riverbed are unstandardised and fail to document key river properties that impact on the hydrodynamic and transport processes of MP particles, hindering our understanding of MP behaviour in riverine systems. Using ten criteria based on the reportage of the catchment area, river characteristics of sampling sites and approach, we reviewed the sampling procedures employed in 36 field-based river studies that quantify MP presence in the water column and benthic sediment. Our results showed that a limited number of studies conducted reliable sampling procedures in accordance with the proposed quality criteria, with 35 of the 36 studies receiving a score of zero for at least one criterion, indicating the omission of critical information relating to the study's sample size and the physical and hydraulic characteristics of the sampled river. On the other hand, a good number of studies adequately documented the spatial information of the sampling sites, the vertical location of sample collection, and sampling equipment used. An idealised MP sampling approach is presented to ensure that future studies are harmonised and variables underpinning MP transport in rivers are reported. In addition, a meta-analysis on MP particle characteristics from these studies found that concentrations in the riverine water column and benthic sediment are highly variable, varying by five and seven orders of magnitude respectively, and are heavily dependent on the sampling equipment used. Polypropylene (PP), polyethene, (PE), polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) were the most frequently reported MP polymers, while irregular-shaped particles, fibres, spheres, and films were the most commonly reported shapes in the river studies. These results highlight the urgent need to standardise sampling procedures and include key contextual information to improve our understanding of MP behaviour and transport in the freshwater environment.

Microplastics removal from a primary settler tank in a wastewater treatment plant and estimations of contamination onto European agricultural land via sewage sludge recycling.

Wastewater treatment plants (WwTPs) remove microplastics (MPs) from municipal sewage flow, with the resulting bulk of MPs being concentrated within generated sewage sludge which is frequently recycled back onto agricultural land as accepted practice in many European countries as a sustainable fertiliser resource. This circular process means that MPs successfully removed from WwTPs are deposited into the soil and able to return into the natural watercourse by means of run-off or infiltration to groundwater. This study quantifies the removal efficiency of MPs with size ranging between 1000 and 5000 µm in a primary settlement tank (PST) at a WwTP serving a population equivalent of 300,000 and provides MP concentrations in the generated sewage sludge. Our study revealed that the proportion of MPs partitioning in a PST to settled sludge, floating scum and effluent was 96%, 4% and 0% respectively, implying 100% removal of MPs of 1000-5000 µm in size. The generated sewage sludge was estimated to contain concentrations of approximately 0.01 g of MPs or 24.7 MP particles per g of dry sewage sludge solid, equivalent to ∼1% of the sewage sludge weight. Using these figures and data from the European Commission and Eurostat, the potential yearly MP contamination onto soils throughout European nations is estimated to be equivalent to a mass of MPs ranging between 31,000 and 42,000 tonnes (considering MPs 1000-5000 µm in size) or 8.6×1013-7.1×1014 MP particles (considering MPs 25-5000 µm in size). An estimated maximum application rate of 4.8 g of MP/m2/yr or 11,489 MP particles/m2/yr, suggests that the practice of spreading sludge on agricultural land could potentially make them one of the largest global reservoirs of MP pollution. Hence, recycling raw sewage sludge onto agricultural soils should be reviewed to avoid introducing extreme MP pollution into the environment.

Temperature surpasses the effects of velocity and turbulence on swimming performance of two invasive non-native fish species.

Global climate change continues to impact fish habitat quality and biodiversity, especially in regard to the dynamics of invasive non-native species. Using individual aquaria and an open channel flume, this study evaluated the effects of water temperature, flow velocity and turbulence interactions on swimming performance of two lentic, invasive non-native fish in the UK, pumpkinseed (Lepomis gibbosus) and topmouth gudgeon (Pseudorasbora parva). Burst and sustained swimming tests were conducted at 15, 20 and 25°C. Acoustic Doppler velocimetry was used to measure the flume hydrodynamic flow characteristics. Both L. gibbosus and P. parva occupied the near-bed regions of the flume, conserving energy and seeking refuge in the low mean velocities flow areas despite the relatively elevated turbulent fluctuations, a behaviour which depended on temperature. Burst swimming performance and sustained swimming increased by up to 53% as temperature increased from 15 to 20°C and 71% between 15 and 25°C. Furthermore, fish test area occupancy was dependent on thermal conditions, as well as on time-averaged velocities and turbulent fluctuations. This study suggests that invasive species can benefit from the raised temperatures predicted under climate change forecasts by improving swimming performance in flowing water potentially facilitating their further dispersal and subsequent establishment in lotic environments.

Challenges and opportunities of the COVID-19 pandemic for perinatal mental health care: a mixed-methods study of mental health care staff.

The aim of this study was to explore staff perceptions of the impact of the COVID-19 pandemic on mental health service delivery and outcomes for women who were pregnant or in the first year after birth ('perinatal' women). Secondary analysis was undertaken of an online mixed-methods survey open to all mental health care staff in the UK involving 363 staff working with women in the perinatal period. Staff perceived the mental health of perinatal women to be particularly vulnerable to the impact of stressors associated with the pandemic such as social isolation (rated by 79.3% as relevant or extremely relevant; 288/363) and domestic violence and abuse (53.3%; 192/360). As a result of changes to mental health and other health and social care services, staff reported feeling less able to assess women, particularly their relationship with their baby (43.3%; 90/208), and to mobilise safeguarding procedures (29.4%; 62/211). While 42% of staff reported that some women engaged poorly with virtual appointments, they also found flexible remote consulting to be beneficial for some women and helped time management due to reductions in travel time. Delivery of perinatal care needs to be tailored to women's needs; virtual appointments are perceived not to be appropriate for assessments but may be helpful for some women in subsequent interactions. Safeguarding and other risk assessment procedures must remain robust in spite of modifications made to service delivery during pandemics.

Data for semi-permanent cationic coating for protein separations.

Protein separations and analyses are fundamental to fields of study that include biochemistry, biology, physiology, drug discovery, pharmaceuticals, as well as agricultural and food based industries. Here, we provide the data from a novel phospholipid-cetyltrimethylammonium bromide coating capable of separating cationic and anionic proteins with high efficiency. Capillary electrophoresis separations of protein standards were utilized to characterize the performance of the novel coating. Using capillary electrophoresis with UV absorbance detection a working pH range of 4-9 was identified, with reproducibility in time ≤1% relative standard deviation, and plate counts for proteins as high as 480,000 plates (lysozyme, pH 7). Further details and results from these data are available in the work reported by Crihfield et al. and can be accessed at https://doi.org/10.1016/j.chroma.2019.460397 [1].

Is there an increased risk of perinatal mental disorder in women with gestational diabetes? A systematic review and meta-analysis.

AIM: Gestational diabetes (GDM) and mental disorder are common perinatal morbidities and are associated with adverse maternal and child outcomes. While there is a relationship between type 2 diabetes and mental disorder, the relationship between GDM and mental disorder has been less studied. We conducted a systematic review and meta-analysis of the prevalence of mental disorders in women with GDM and their risk for mental disorders compared with women without GDM. METHODS: Published, peer-reviewed literature measuring prevalence and/or odds of GDM and perinatal mental disorders was reviewed systematically. Risk of bias was assessed using a checklist. Two independent reviewers were involved. Analyses were grouped by stage of peripartum, i.e. antepartum at the time of GDM diagnosis and after diagnosis, and in the postpartum. RESULTS: Sixty-two studies were included. There was an increased risk of depressive symptoms in the antenatal period around the time of diagnosis of GDM [odds ratio (OR) 2.08; 95% confidence interval (CI) 1.42, 3.05] and in the postnatal period (OR 1.59; 95% CI 1.26, 2.00). CONCLUSIONS: Given the potential relationship between GDM and perinatal mental disorders, integration of physical and mental healthcare in women experiencing GDM and mental disorders could improve short- and long-term outcomes for women and their children.

The cost of infection: Argulus foliaceus and its impact on the swimming performance of the three-spined stickleback (Gasterosteus aculeatus).

For fish, there can be multiple consequences of parasitic infections, including the physical impacts on swimming and the pathological costs of infection. This study used the three-spined stickleback (Gasterosteus aculeatus) and the ectoparasitic fish louse, Argulus foliaceus, to assess both physical (including form drag and mass) and pathological effects of infection. Both sustained (prolonged swimming within an open channel flume) and burst (C-start) swimming performance were measured on individual fish before (trials 1-2) and after infection (trials 3-5). Experimental infection occurred shortly before the third trial, when the physical impacts of infection could be separated from any subsequent pathology as transmission of adult parasites causes instantaneous drag effects prior to observable pathology. Despite the relatively large size of the parasite and corresponding increase in hydrodynamic drag for the host, there were no observable physical effects of infection on either sustained or burst host swimming. By contrast, parasite-induced pathology is the most probable explanation for reduced swimming performance across both tests. All sticklebacks displayed a preference for flow refugia, swimming in low-velocity regions of the flume, and this preference increased with both flow rate and infection time. This study suggests that even with large, physically demanding parasites their induced pathology is of greater concern than direct physical impact.

Etiology of Corpus Callosum Lesions with Restricted Diffusion.

PURPOSE: Infarction of the corpus callosum is rare, and other conditions can cause magnetic resonance imaging (MRI) restricted diffusion in the callosum, leading to diagnostic uncertainty. We sought to characterize the etiology of lesions with diffusion restriction in the corpus callosum. METHODS: Callosal lesions with restricted diffusion were identified at our institution between January 2000 and December 2010. Radiographic and clinical data were reviewed to determine whether the lesion was vascular and if so, to identify the underlying mechanism. RESULTS: A total of 174 cases were reviewed in depth; 47 % were vascular and 53 % were nonvascular. Among vascular cases, atypical mechanisms of stroke (e.g., vasculitis/vasculopathy, hypercoagulable state) were most common (37 %), followed by cardioembolism (28 %). Vascular splenial lesions in particular were likely due to atypical causes of stroke. The most common nonvascular etiologies were trauma (44 %), tumor (22 %), and demyelination (15 %). Vascular lesions were more common in older, non-Caucasian patients with vascular risk factors. Nonvascular lesions were more likely to be found in association with T2-hyperintense cortical lesions, focal intraparenchymal enhancement, or edema/mass effect on MRI. CONCLUSIONS: More than half of lesions with diffusion restriction in the corpus callosum are due to a nonvascular cause. Clinical and radiographic characteristics can help distinguish vascular from nonvascular lesions in the corpus callosum. Nonvascular lesions are more likely to be seen in younger patients without vascular risk factors and are more often accompanied by enhancement and edema. Vascular lesions are most commonly due to atypical stroke etiologies, and these patients may require additional diagnostic testing.

Printed three-dimensional airway model assists planning of single-lung ventilation in a small child.

BACKGROUND: Single-lung ventilation in infants and small children is challenging because suitable sizes of double-lumen cuffed tracheal tubes are not available. A 6-yr-old child required pulmonary saline washout for primary alveolar proteinosis, and therefore needed sequential single-lung ventilation in order to achieve safe oxygenation. Before undertaking this potentially hazardous procedure, we practised bronchial intubation on an anatomical model of her airway constructed from computed tomography (CT) data. METHODS: We created a full-scale, anatomically accurate, transparent plastic model of the trachea and main bronchi on a three-dimensional printer using data from a CT scan. We then performed several different airway approaches to identify those likely to be most suitable, ex vivo, before the clinical procedure was carried out on the patient. RESULTS: The model helped us to choose the type and size of bronchial tubes and to practise their insertion beforehand. Subsequently, during anaesthesia, the chosen technique was successful. CONCLUSIONS: Three-dimensional printing of a model of the airway of a small child aided planning of bronchial intubation and single-lung ventilation. Three-dimensional printing of airway structures may have wider application in anaesthesia practice.

Combined effects of flow condition and parasitism on shoaling behaviour of female guppies Poecilia reticulata.

Group living in fish can provide benefits of protection from predators and some parasites, more efficient foraging for food, increased mating opportunities and enhanced energetic benefit when swimming. For riverine species, shoaling behaviour can be influenced by various environmental stressors, yet little is known how flow rate might influence the shoaling of diseased fish shoals. In view of the increasingly unpredictable flow rates in streams and rivers, this study aimed to assess the combined effect of flow condition and parasitism on the shoaling behaviour of a model fish species. Shoal size, shoal cohesion and time spent shoaling of female guppies Poecilia reticulata were compared when infected with the directly transmitted ectoparasite Gyrodactylus turnbulli under flow and static conditions. Flow condition was an important factor in influencing shoaling behaviour of guppies with the fish forming larger shoals in the absence of flow. When a shoal member was infected with G. turnbulli, shoal cohesion was reduced, but the magnitude of this effect was dependent on flow condition. In both flow and static conditions, bigger fish formed larger shoals than smaller counterparts. Future changes to stream hydrology with more frequent flooding and drought events will affect the shoaling tendency of fish. During high-flow events, diseased fish may not be able to keep up with shoal mates and therefore have a higher risk of predation. Additionally, these findings may be important for aquaria and farmed species where an increase in flow rate may reduce aggregation in fish.

Fish responses to flow velocity and turbulence in relation to size, sex and parasite load.

Riverine fish are subjected to heterogeneous flow velocities and turbulence and may use this to their advantage by selecting regions that balance energy expenditure for station holding while maximizing energy gain through feeding opportunities. This study investigated microhabitat selection by guppies Poecilia reticulata in terms of flow characteristics generated by hemisphere boulders in an open channel flume. Velocity and turbulence influenced the variation in swimming behaviour with respect to size, sex and parasite intensity. With increasing body length, fish swam further and more frequently between boulder regions. Larger guppies spent more time in the areas of high-velocity and low-turbulence regions beside the boulders, whereas smaller guppies frequented the low-velocity and high-turbulence regions directly behind the boulders. Male guppies selected the regions of low velocity, indicating possible reduced swimming ability owing to hydrodynamic drag imposed by their fins. With increasing Gyrodactylus turnbulli burden, fish spent more time in regions with moderate velocity and lowest turbulent kinetic energy which were the most spatially and temporally homogeneous in terms of velocity and turbulence. These findings highlight the importance of heterogeneous flow conditions in river channel design owing to the behavioural variability within a species in response to velocity and turbulence.

Digitial endochondroma.

A patient with Ollier disease presenting with onycholysis and nail dystrophy related to a subungual enchondroma is presented.

Variable prenatal stress results in impairments of sustained attention and inhibitory response control in a 5-choice serial reaction time task in rats.

Rats repeatedly exposed to variable prenatal stress (PNS) exhibit schizophrenia-like behavioral signs such as social withdrawal, elevations in amphetamine-induced locomotor activity, deficits in sensory-motor gating, as well as impairments in memory-related task performance. However, to date there have been no studies designed to test the hypothesis that variable PNS would lead to disruptions in sustained attention and inhibitory response control (i.e., symptoms also commonly observed in schizophrenia and other neuropsychiatric disorders such as attention-deficit hyperactivity disorder). In the current study, the effects of variable PNS in rats were evaluated in fixed and variable stimulus duration (VSD) as well as variable intertrial interval (VITI) versions of a 5-choice serial reaction time task (5C-SRTT). In a separate series of experiments, the glutamate (N-methyl-d-aspartate [NMDA]) antagonist, MK-801 (0.025-0.05 mg/kg), and the norepinephrine reuptake inhibitor, atomoxetine (0.30-3.0mg/kg), were administered acutely to assess the sensitivity of PNS subjects to glutamatergic and noradrenergic manipulations. The results indicated that exposure to variable PNS significantly impaired accuracy in the VSD version of the 5C-SRTT and increased premature and timeout responses in the VITI version. In addition, both doses of MK-801 impaired accuracy, increased premature and timeout responses in PNS, but not control subjects. In contrast, atomoxetine decreased premature and timeout responses in both PNS and control subjects in the VITI version of the task and improved accuracy in the PNS subjects. The results suggest that exposure to variable PNS in rats results in impairments of sustained attention and inhibitory response control and that these deficits can be exacerbated by NMDA antagonism and improved by a norepinephrine uptake inhibitor. Collectively, these data further support the premise that variable PNS in rats is a valid model system for the study of neuropsychiatric disorders and their treatment.

The effect of thermal hydrolysis pretreatment on the anaerobic degradation of nonylphenol and short-chain nonylphenol ethoxylates in digested biosolids.

The presence of micropollutants can be a concern for land application of biosolids. Of particular interest are nonylphenol diethoxylate (NP(2)EO), nonylphenol monoethoxylate (NP(1)EO), and nonylphenol (NP), collectively referred to as NPE, which accumulate in anaerobically digested biosolids and are subject to regulation based on the environmental risks associated with them. Because biosolids are a valuable nutrient resource, it is essential that we understand how various treatment processes impact the fate of NPE in biosolids. Thermal hydrolysis (TH) coupled with mesophilic anaerobic digestion (MAD) is an advanced digestion process that destroys pathogens in biosolids and increases methane yields and volatile solids destruction. We investigated the impact of thermal hydrolysis pretreatment on the subsequent biodegradation of NPE in digested biosolids. Biosolids were treated with TH, anaerobic digestion, and aerobic digestion in laboratory-scale reactors, and NPE were analyzed in the influent and effluent of the digesters. NP(2)EO and NP(1)EO have been observed to degrade to the more estrogenic NP under anaerobic conditions; therefore, changes in the ratio of NP:NPE were of interest. The increase in NP:NPE following MAD was 56%; the average increase of this ratio in four sets of TH-MAD samples, however, was only 24.6 ± 3.1%. In addition, TH experiments performed in pure water verified that, during TH, the high temperature and pressure alone did not directly destroy NPE; TH experiments with NP added to sludge also showed that NP was not destroyed by the high temperature and pressure of TH when in a more complex sludge matrix. The post-aerobic digestion phases removed NPE, regardless of whether TH pretreatment occurred. This research indicates that changes in biosolids processing can have impacts beyond just gas production and solids destruction.

Alogliptin as a third oral antidiabetic drug in patients with type 2 diabetes and inadequate glycaemic control on metformin and pioglitazone: a 52-week, randomized, double-blind, active-controlled, parallel-group study.

AIM: To assess the efficacy and safety of adding alogliptin versus uptitrating pioglitazone in patients with type 2 diabetes and inadequate glycaemic control on metformin and pioglitazone. METHODS: In this randomized, double-blind, active-controlled, parallel-group study, patients with type 2 diabetes and A1c ≥7.0 and ≤10.0% on metformin (≥1500 mg or maximum tolerated dose; Met) and pioglitazone 30 mg (Pio30) received alogliptin 25 mg (Alo25; n = 404) or pioglitazone 15 mg (n = 399) added to Met+Pio30 for 52 weeks. The primary endpoint was change from baseline (CFB) in A1c at weeks 26 and 52, with sequential testing for non-inferiority of Met+Pio30+Alo25 at weeks 26 and 52 and then for superiority at week 52. RESULTS: Met+Pio30+Alo25 showed superior glycaemic control versus Met+Pio45 at week 52 [least squares (LS) mean CFB in A1c, -0.70 vs. -0.29%; p < 0.001]. At week 52, Met+Pio30+Alo25 resulted in greater CFB in A1c regardless of baseline A1c (p < 0.001); higher proportions of patients achieving A1c ≤7.0 (33.2 vs. 21.3%) and ≤6.5% (8.7 vs. 4.3%; p < 0.001); greater CFB in fasting plasma glucose (FPG; LS mean CFB, -0.8 vs. -0.2 mmol/L; p < 0.001); and greater improvements in measures of ß-cell function (p < 0.001). Hypoglycaemia incidence was low (Met+Pio30+Alo25, 4.5%; Met+Pio45, 1.5%), mostly mild to moderate, but with two severe events in the Met+Pio30+Alo25 group. No meaningful differences in incidences of individual adverse events were observed between treatments. CONCLUSIONS: Adding alogliptin to an existing metformin-pioglitazone regimen provided superior glycaemic control and potentially improved ß-cell function versus uptitrating pioglitazone in patients with type 2 diabetes, with no clinically important differences in safety.

Injury to recreational and professional cricket players: circumstances, type and potential for intervention.

This paper describes injury (circumstances and type) experienced by sub-populations at all levels of cricket and, where possible, the type of protective equipment used. The sample differs to that generally examined in the literature in that it is not restricted to evaluation of elite and professional players only. Over a 6-year period (2000-2005), 498 cases were identified. The average age of injury was 27 years and 86% of those injured were male. The population incidence rate was 2.3 per 100,000 per year, and participation incidence rate 39 per 100,000 per year. Over all age groups upper limb (36%) and lower limb (31%) were most commonly injured. Fracture was the main type of injury. Differences among age groups were identified. Children (<10 years) most commonly suffered head injury (contact with the bat); 10-19 year olds, head, upper and lower limb injury (in similar proportions) generally from contact with bat/ball; those over 20 years mainly had upper and lower limb injuries. Contact with the bat/ball was the dominant mechanism of injury for those under 50 years of age while overexertion, strenuous or repetitive movements, slips and falls were the mechanisms for those over 50. The large number of head injuries to children is of concern and both these, and the substantial number of injuries to the hand/phalanges (63% of all upper limb injuries), are important targets for injury prevention. The difference in injury patterns between children and adults is indicative of a need to develop, and use, different types of PPE at different skill/age levels.

Alogliptin added to insulin therapy in patients with type 2 diabetes reduces HbA(1C) without causing weight gain or increased hypoglycaemia.

AIMS: To assess the efficacy and safety of alogliptin added to insulin in patients with type 2 diabetes inadequately controlled with insulin alone or combined with metformin. METHODS: In this 26-week, double-blind, placebo-controlled study, 390 patients were randomized to receive alogliptin 12.5 mg (n = 131), alogliptin 25 mg (n = 129) or placebo (n = 130) once daily, as add-on to stable insulin therapy with or without metformin. The primary endpoint was change in haemoglobin A(1C) (HbA(1C)) at week 26. RESULTS: At week 26, mean HbA(1C) changes from the mean baseline value of 9.3% were significantly greater for alogliptin 12.5 mg (-0.63 +/- 0.08%) and alogliptin 25 mg (-0.71 +/- 0.08%) than placebo (-0.13 +/- 0.08%; p < 0.001). Significantly greater proportions of patients receiving alogliptin 12.5 or 25 mg than placebo had HbA(1C) decreases of > or =0.5, > or =1.0 and > or =1.5%. Insulin doses remained unchanged, and there were no differences in the proportions of patients experiencing hypoglycaemia among placebo (24%), alogliptin 12.5 mg (27%) and alogliptin 25 mg (27%). Mean weight increases from baseline at week 26 were similar for placebo (0.6 +/- 0.2 kg), alogliptin 12.5 mg (0.7 +/- 0.2 kg) and alogliptin 25 mg (0.6 +/- 0.2 kg). Incidences of overall adverse events, and of gastrointestinal, dermatological and infection-related events, were similar among groups. CONCLUSIONS: Adding alogliptin to previous insulin therapy (with or without metformin) significantly improved glycaemic control in patients with type 2 diabetes inadequately controlled on insulin, without causing weight gain or increasing the incidence of hypoglycaemia. Further studies are warranted to explore the role of alogliptin added to optimized basal insulin regimens.

The anti-dopaminergic agent, haloperidol, antagonises the feminising effect of neonatal serotonin on sexually dimorphic hypothalamic nuclei and tyrosine hydroxylase immunoreactive neurones.

There is a transient fall in hypothalamic serotonin (5-hydroxytryptamine; 5-HT) activity in the second week post partum in male but not female rats. When this fall is masked by administration of the 5-HT(2) agonist (-) 2,5-dimethoxy-4-iodophenyl]-2-aminopropane hydrochloride [(-)DOI], over days 8-16 post partum, males are feminised in adulthood. To investigate whether the effect of 5-HT is mediated by dopamine and whether testosterone exerts its masculinising effect by reducing 5-HT and dopamine activity, male pups were treated with (-)DOI alone or together with the dopamine antagonist, haloperidol, over days 8-16 post partum, whereas females were treated with testosterone propionate on day 2 post partum. In adulthood, the volumes of the anteroventral periventricular nucleus (AVPV), sexually dimorphic nucleus of the preoptic area (SDN-POA) and arcuate nucleus (ARC) were determined, together with the number of tyrosine hydroxylase-immunoreactive (TH-ir) cells and fibres within them. The concentrations of 5-HT, dopamine and their metabolites were also measured. (-)DOI treatment increased the volume of the AVPV, decreased that of the SDN-POA and increased the number of TH-ir cells in the AVPV. These feminising effects were antagonised by concurrent haloperidol treatment. Neonatal testosterone propionate masculinised the volumes of the female AVPV and SDN-POA and reduced the number of TH-ir cells in the AVPV. Dopamine and 5-HT turnover in the AVPV was greater in female compared to male rats and neonatal testosterone propionate reduced dopamine concentration in the female AVPV. Neonatal (-)DOI had no effect on dopamine and 5-HT activity in the AVPV but increased both in the ARC. The findings that TH-ir neurone number and dopamine activity are greater in the female AVPV; the feminising effect of 5-HT is prevented by a haloperidol; and the masculinising effect of testosterone propionate is accompanied by a decrease in TH-ir neurone number and dopamine concentration in the female AVPV, suggest that dopamine is involved in hypothalamic sexual differentiation and may mediate the effect of 5-HT.