PET imaging of serotonin 1A receptor binding in depression

BACKGROUND

The serotonin-1A (5HT1A) receptor system has been implicated in the pathophysiology of major depression by postmortem studies of suicide victims and depressed subjects dying of natural causes. This literature is in disagreement, however, regarding the brain regions where 5HT1A receptor binding differs between depressives and controls and the direction of such differences relative to the normal baseline, possibly reflecting the diagnostic heterogeneity inherent within suicide samples. PET imaging using the 5HT1A receptor radioligand, [11C]WAY-100635, may clarify the clinical conditions under which 5HT1A receptor binding potential (BP) is abnormal in depression.

METHODS

Regional 5HT1A receptor BP values were compared between 12 unmedicated depressives with primary, recurrent, familial mood disorders and 8 healthy controls using PET and [carbonyl-11C]WAY-100635. Regions-of-interest (ROI) assessed were the mesiotemporal cortex (hippocampus-amygdala) and midbrain raphe, where previous postmortem studies suggested 5HT1A receptor binding is abnormal in depression.

RESULTS

The mean 5HT1A receptor BP was reduced 41.5% in the raphe (p < .02) and 26.8% in the mesiotemporal cortex (p < .025) in the depressives relative to the controls. Post hoc comparisons showed the abnormal reduction in 5HT1A receptor BP was not limited to these regions, but extended to control ROI in the occipital cortex and postcentral gyrus as well. The magnitude of these abnormalities was most prominent in bipolar depressives (n = 4) and unipolar depressives with bipolar relatives (n = 4).

CONCLUSIONS

Serotonin-1A receptor BP is abnormally decreased in the depressed phase of familial mood disorders in multiple brain regions. Of the regions tested, the magnitude of this reduction was most prominent in the midbrain raphe. Converging evidence from postmortem studies of mood disorders suggests these reductions of 5HT1A receptor BP may be associated with histopathological changes involving the raphe.

Quantitative detection of protein expression in single cells using droplet microfluidics

We demonstrate that single cells can be controllably compartmentalized within aqueous microdroplets; using such an approach we perform high-throughput screening by detecting the expression of a fluorescent protein in individual cells with simultaneous measurement of droplet size and cell occupancy.

Genetic epidemiology of Sarcoptes scabiei (Acari: Sarcoptidae) in northern Australia

Utilising three hypervariable microsatellite markers we have previously shown that scabies mites on people are genetically distinct from those on dogs in sympatric populations in northern Australia. This had important ramifications on the formulation of public health control policies. In contrast phylogenetic analyses using mitochondrial markers on scabies mites infecting multiple animal hosts elsewhere in the world could not differentiate any genetic variation between mite haplotype and host species. Here we further analyse the intra-specific relationship of Sarcoptes scabiei var. hominis with S. scabiei var. canis by using both mitochondrial DNA and an expanded nuclear microsatellite marker system. Phylogenetic studies using sequences from the mitochondrial genes coding for 16S rRNA and Cytochrome Oxidase subunit I demonstrated significant relationships between S. scabiei MtDNA haplotypes, host species and geographical location. Multi-locus genotyping using 15 microsatellite markers substantiated previous data that gene flow between scabies mite populations on human and dog hosts is extremely rare in northern Australia. These data clearly support our previous contention that control programs for human scabies in endemic areas with sympatric S. scabiei var. hominis and var. canis populations must focus on human-to-human transmission. The genetic division of dog and human derived scabies mites also has important implications in vaccine and diagnostic test development as well as the emergence and monitoring of drug resistance in S. scabiei in northern Australia.

Plasma concentrations of lignocaine during fibreoptic bronchoscopy

Peak plasma concentrations of lignocaine were recorded in 41 patients receiving topically applied lignocaine for fiberoptic bronchoscopy. Adequate anaesthesia was achieved in all patients with an average dose per unit weight of 9.3 +/- 0.5 mg/kg (SEM) giving a mean peak plasma concentration of 2.9 +/- 0.5 mg/l-1 (SEM) (+/- SEM 0.5). The plasma concentration exceeded toxic levels of 5.0 mg/l-1 in only two patients, and no complications were observed. Peak concentrations were influenced only by dose per unit weight administered and not by factors considered likely to influence mucosal absorption from the bronchial tree, such as sputum production, airflow obstruction, or cigarette smoking. A major proportion of the total dose of lignocaine was required to anaesthetise the nose, pharynx, and larynx, only a small proportion being needed for the bronchial tree. Lignocaine gel (2% w/v) was preferred by patients, and in a study of 10 volunteers, produced lower plasma concentrations when used as a topical anaesthetic than did lignocaine aerosol (10% w/v) or lignocaine solution (4% w/v).

PET measures of amphetamine-induced dopamine release in ventral versus dorsal striatum

Regional differences in dextroamphetamine (AMPH)-induced dopamine (DA) release in the baboon striatum were assessed using positron emission tomographic (PET) measures of [11C]raclopride specific binding to DA D2/D3 receptors acquired before and after AMPH administration. The magnitude of the reduction in [11C]raclopride binding, following AMPH administration, was two-fold greater in the anteroventral striatum (comprised of ventral caudate, anteroventral putamen, and nucleus accumbens) than the dorsal striatum (dorsal caudate). A simulation study demonstrated that any potential biases due to resolution (partial volume) and alignment effects were significantly smaller than the magnitude of the observed results. These regional differences in the sensitivity of AMPH are compatible with microdialysis evidence in rats indicating that the magnitude of DA release in response to AMPH concentrations in the range tested is greater in ventral than dorsal striatal regions. Post hoc tests involving measures in other striatal regions showed that the baseline DA D2/D3 binding was highest and the correlation between AMPH dose and change in [11C]raclopride binding most significant in the putamen.

Are those in need taking dietary supplements? A survey of 21 923 adults

Many people take dietary supplements, but information on characteristics associated with their use is lacking. The relationship between lifestyle behaviours, morbidity and use of dietary supplements has not been examined and earlier studies have limited applicability to a general population. These issues were addressed in the current study. Information was obtained by postal questionnaire sent to a sample of the general population. The questionnaire was completed by 70.5 % of the sample (15 465 from a total sample of 21 923), with at least one-third (35.5 %) taking dietary supplements. In adjusted analyses, supplement users were more likely to be women, white, home-owners, non-smokers and physically active. Use of vitamin, mineral and/or antioxidant supplements was associated with eating more fruits and vegetables, and taking fish-oil supplements was associated with eating oil-rich fish. A history of CVD or risk factors for CVD reduced the risk of taking vitamins, minerals and/or antioxidants or fish-oil supplements. Those reporting musculoskeletal disorders such as arthritis were more likely to take fish-oil supplements For the first time, we have shown that dietary supplement use is related to different types of morbidity. In particular, people at risk of primary or secondary CVD seem less likely to use dietary supplements, despite possible benefits shown in clinical trials. Public health organisations need to develop guidelines for the public and health professionals regarding the uncontrolled use of dietary supplements in the community.

Sperm swim-up techniques and DNA fragmentation

BACKGROUND

Swim-up techniques for sperm separation may have detrimental effects on sperm DNA. We wished to determine whether the normal swim-up method with centrifugation used in our laboratory, which involves a centrifugation step, was harmful to sperm compared with swim-up without centrifugation.

METHODS

Semen samples were obtained from patients undergoing IVF or andrology assessment. An aliquot was removed for fixation and subsequent DNA fragmentation determination. The remaining sample was divided into two equal parts, which were subjected to swim-up either with (normal swim-up) or without (direct-swim-up) centrifugation. Semen analysis was performed both before and after swim-up. DNA fragmentation, in spermatozoa previously fixed in 4% paraformaldehyde, was assessed by the terminal transferase-mediated DNA end-labelling procedure (TUNEL). The percentage of spermatozoa with DNA damage after each swim-up technique was compared with that in the original semen sample.

RESULTS

DNA damage was <5% in most samples. No significant change in DNA fragmentation was observed between the two swim-up procedures, although the 'normal' swim-up sample had significantly less DNA fragmentation than the pre-swim-up sample.

CONCLUSIONS

We conclude that our normal swim-up technique caused no more DNA damage to spermatozoa from normal semen samples than a direct swim-up technique that involved no centrifugation step.

Gender-specific aging effects on the serotonin 1A receptor

The effects of age on serotonergic function have been hypothesized to underlie age-related changes in mood and behaviors such as sleep and eating. Of particular interest is the serotonin type-1A (5-HT1A) receptor, due to its putative role in mediating the therapeutic efficacy of antidepressant treatment. Using positron emission tomography (PET) and [11C--carbonyl] WAY100635, we assessed 5-HT1A receptor binding in 21 healthy subjects (10 men, 11 women) ranging in age from 21 to 80 years. Regional binding potential values were generated using a reference tissue model and corrected for partial volume effects. We observed an inverse relationship between age and binding of [11C--carbonyl] WAY100635 to the 5-HT1A receptor in men, but not women. This finding is in accord with observations reported in the postmortem literature. Gender-specific effects of age on central serotonergic function may relate to differences between men and women in behavior, mood, and susceptibility to neuropsychiatric disease across the adult lifespan.

Long term outcome of neonatal meningitis

OBJECTIVES

To quantify long term impairment after neonatal meningitis.

DESIGN

Longitudinal case-control study over 9-10 years.

SUBJECTS AND METHODS

A total of 111 children who had suffered neonatal meningitis were seen and compared with 113 matched controls from their birth hospital and 49 controls from general practices. Assessments included the WISC III(UK), movement assessment battery for children (mABC), audiometry, vision testing, and social and medical data. Statistical analysis was by multiple regression, analysis of variance, and chi(2) tests.

RESULTS

Some 10.8% of cases had a severe and 9% a moderate overall outcome compared with 0% and 1.8% for the hospital controls. The mean intelligence quotient (IQ) of the cases (88.8) was significantly less than that of the hospital controls (99.4) or the GP controls (99.6). The mABC score was significantly worse for the cases (7.08) than the hospital (5) or GP (4) controls. Some 3.6% of cases had sensorineural hearing loss, 2.7% had persisting hydrocephalus; no controls did. Some 5.4% of cases and 1.7% of hospital controls had treatment for seizures.

CONCLUSIONS

Severe neurodisability and milder motor and psychometric impairment result from neonatal meningitis. Both clinical follow up and comprehensive developmental assessment are needed after this disease.

Vasopressin and oxytocin secretion in response to the consumption of ecstasy in a clubbing population

Despite the common use of MDMA (ecstasy) in the UK, the mechanism underlying associated potentially fatal cerebral oedema is unclear. We used a new experimental approach working directly with clubbers to perform a study on 30 (17 male) experienced clubbers (mean 6.6 years of clubbing). Pre- and post-clubbing measurements were performed to compare plasma levels of pituitary hormones (vasopressin, oxytocin), plasma and urine osmolality, urinary pH, and plasma sodium and urea. Ecstasy consumption was confirmed by using urinary drug screening pre- and post-clubbing. MDMA was detected in the urine samples of 17 subjects, three of which tested positive during pre-clubbing tests. Mean plasma vasopressin concentration increased in the MDMA group (1.28 +/- 0.29 to 1.43 +/- 0.41 pmol/l), but fell in other participants (1.23 +/- 0.42 to 1.16 +/- 0.0.34 pmol/l). Similarly, mean plasma oxytocin concentrations increased after ingestion of MDMA (2.02 +/- 0.29 to 2.43 +/- 0.24 pmol/l), but fell in the group that did not use MDMA (2.17 +/- 0.36 pmol/l to 1.89 +/- 0.37 pmol/l). There was a significant group by time interaction for plasma osmolality and plasma sodium (p = 0.001 and p = 0.003, respectively) and between change in urinary osmolality (p < 0.001) and MDMA use, with the pattern of change being consistent with the induction of inappropriate vasopressin secretion (also known as SIADH) by MDMA. This report demonstrates SIADH in ecstasy-using "clubbers", which has important clinical implications.

Raised endothelin 1 levels in patients with colorectal liver metastases

BACKGROUND

Endothelin 1 (ET-1), a vasoconstrictor peptide, has been implicated as a tumour growth stimulator and an angiogenesis factor.

METHODS

To assess the involvement of ET-1 in colorectal cancer, immunoelectron microscopy for ET-1 was performed in colorectal liver metastases and normal liver (n = 6). ET-1 plasma levels were measured by radioimmunoassay in patients with colorectal cancer, with (n = 18) and without (n = 12) liver metastases, and in controls (n = 22).

RESULTS

In normal liver, ET-1 was present in endothelial cells; in tumour, it was observed in endothelial cells, tumour cells and myofibroblasts. Mean(s.d.) plasma ET-1 levels were 2.75 (1.37) pg/ml in controls, 4.53(1.61) pg/ml in patients with colorectal liver metastases (P = 0.001) and 3.92(1.32) pg/ml in patients without metastases (P = 0.02).

CONCLUSION

ET-1 was present in various cell types within colorectal liver metastases and raised levels were found in the plasma of patients with colorectal cancer. ET-1 may not only modulate tumour vascular tone but also act on tumour growth and angiogenesis, both locally and systemically.

Transient reactive papulotranslucent acrokeratoderma associated with cystic fibrosis

A 20-year-old female with cystic fibrosis presented with a white marginal palmar eruption after exposure to water. There was no family history of keratoderma. A biopsy showed hyperkeratosis around dilated eccrine ostia. These features are similar to a recently described condition, transient reactive papulotranslucent acrokeratoderma. This is thought to be a variant of hereditary papulotranslucent acrokeratoderma, one of the punctate keratodermas. Association with cystic fibrosis has not been described previously.

The teratogenicity of methoxyacetic acid in the rat

Intraperitoneal (i.p.) administration of methoxyacetic acid (MAA) to rats on Day 8, 10, 12 or 14 of pregnancy was embryolethal and teratogenic. Skeletal anomalies, hydrocephalus and dilatation of the kidney pelvis were the most common malformations. Embryonic response to MAA varied with gestational age and with dosage (0.1 to 2.5 mmol/kg). These actions are similar to those previously reported for 2-methoxyethanol (ME) and dimethoxyethyl phthalate (DMEP). Embryos were also examined on Day 12, 48 h following i.p. administration of 2.5 mmol/kg MAA. Abnormalities were comparable to those previously observed following MAA treatment of rat conceptuses in culture. These data support the conclusion that MAA is the proximal teratogenic metabolite of ME and DMEP.

Quantitative two dimensional echocardiography during bicycle exercise in normal subjects

A quantitative two dimensional echocardiographic study was conducted in 10 normal subjects performing bicycle exercise in a supine position. Standardized two dimensional echocardiographic short axis and apical views of the left ventricle were analyzed to derive left ventricular sectional areas and length. Over a range of exercise heart rates from 108 to 152 beats/min, satisfactory two dimensional echocardiographic views and measurements were obtained for quantitative assessment of sectional and global left ventricular function. Variability of left ventricular short axis area measurements ranged from 2.9 to 8.3 percent. Left ventricular volume reconstruction employed a simplified formula (volume = 5/6 area X length) with a single papillary muscle level short axis area and left ventricular length. Changes in left ventricular function from rest to exercise quantitated by two dimensional echocardiography indicated a significant reduction in end-systolic volume (from 28.1 +/- 5.6 to 20.8 +/- 4.3 cc/m2, p less than 0.001) and increased left ventricular ejection fraction (from 63.4 +/- 6.3 to 72.1 +/- 5.7 percent, p less than 0.001). The change in end-diastolic volume was not significant. It is concluded that standardized two dimensional echocardiographic study during supine bicycle exercise in normal subjects provides good reproducibility of measurement of sectional and global left ventricular function. Quantitative two dimensional echocardiographic exercise study of global as well as segmental left ventricular performance in patients may be feasible using standardized procedure and analysis.

BDNF, relative preference, and reward circuitry responses to emotional communication

Brain derived neurotrophic factor (BDNF) regulates neural development and synaptic transmission. We have tested the hypothesis that functional variation in the BDNF gene (Val66Met polymorphism, rs6265) affects brain reward circuitry encoding human judgment and decision-making regarding relative preference. We quantified relative preference among faces with emotional expressions (angry, fearful, sad, neutral, and happy) by a keypress procedure performed offline to measure effort traded for viewing time. Keypress-based relative preferences across the ensemble of faces were mirrored significantly by fMRI signal in the orbitofrontal cortex, amygdala, and hippocampus when passively viewing these faces. For these three brain regions, there was also a statistically significant group difference by BDNF genotype in the fMRI responses to the emotional expressions. In comparison with Val/Met heterozygotes, Val/Val individuals preferentially sought exposure to positive emotions (e.g., happy faces) and had stronger regional fMRI activation to aversive stimuli (e.g., angry, fearful, and sad faces). BDNF genotype accounted for approximately 30% of the variance in fMRI signal that mirrors keypress responses to these stimuli. This study demonstrates that functional allelic variation in BDNF modulates human brain circuits processing reward/aversion information and relative preference transactions.

High-resolution melt analysis for the detection of a mutation associated with permethrin resistance in a population of scabies mites

Permethrin as a topical acaricide cream is widely used to treat scabies. The neuronal voltage-sensitive sodium channel (Vssc), necessary for the generation of action potentials in excitable cells, is the target of pyrethroid acaricides such as permethrin. Pyrethroid resistance has been linked to specific mutations in the Vssc gene. Following the partial sequencing of the Vssc gene in the scabies mite Sarcoptes scabiei (L.) (Astigmata: Sarcoptidae), we compared Vssc gene sequences from permethrin-sensitive and -tolerant S. scabiei var. canis Gerlach mites, and identified a G to A single nucleotide polymorphism (SNP) in permethrin-tolerant mites resulting in an amino acid change from glycine to aspartic acid in domain III S6. The mutation is in a region of the gene where mutations have been identified in a range of pyrethroid-resistant arthropods. Results of in vitro permethrin exposure assays showed that survival rates for mites bearing the mutation were similar to those previously reported for mites from human subjects where clinical tolerance to permethrin had been observed. A real-time polymerase chain reaction-high-resolution melt (PCR-HRM) assay was developed to detect this SNP. This assay provides a useful methodology for screening for this and other mutations associated with permethrin resistance in scabies mite populations and thus facilitates surveillance for acaricide resistance.

Test-retest variability of serotonin 5-HT2A receptor binding measured with positron emission tomography and [18F]altanserin in the human brain

The role of serotonin in CNS function and in many neuropsychiatric diseases (e.g., schizophrenia, affective disorders, degenerative dementias) support the development of a reliable measure of serotonin receptor binding in vivo in human subjects. To this end, the regional distribution and intrasubject test-retest variability of the binding of [18F]altanserin were measured as important steps in the further development of [18F]altanserin as a radiotracer for positron emission tomography (PET) studies of the serotonin 5-HT2A receptor. Two high specific activity [18F]altanserin PET studies were performed in normal control subjects (n = 8) on two separate days (2-16 days apart). Regional specific binding was assessed by distribution volume (DV), estimates that were derived using a conventional four compartment (4C) model, and the Logan graphical analysis method. For both analysis methods, levels of [18F]altanserin binding were highest in cortical areas, lower in the striatum and thalamus, and lowest in the cerebellum. Similar average differences of 13% or less were observed for the 4C model DV determined in regions with high receptor concentrations with greater variability in regions with low concentrations (16-20%). For all regions, the absolute value of the test-retest differences in the Logan DV values averaged 12% or less. The test-retest differences in the DV ratios (regional DV values normalized to the cerebellar DV) determined by both data analysis methods averaged less than 10%. The regional [18F]altanserin DV values using both of these methods were significantly correlated with literature-based values of the regional concentrations of 5-HT2A receptors determined by postmortem autoradiographic studies (r2 = 0.95, P < 0.001 for the 4C model and r2 = 0.96, P < 0.001 for the Logan method). Brain uptake studies in rats demonstrated that two different radiolabeled metabolites of [18F]altanserin (present at levels of 3-25% of the total radioactivity in human plasma 10-120 min postinjection) were able to penetrate the blood-brain barrier. However, neither of these radiolabeled metabolites bound specifically to the 5-HT2A receptor and did not interfere with the interpretation of regional [18F]altanserin-specific binding parameters obtained using either a conventional 4C model or the Logan graphical analysis method. In summary, these results demonstrate that the test-retest variability of [18F]altanserin-specific binding is comparable to that of other PET radiotracers and that the regional specific binding of [18F]altanserin in human brain was correlated with the known regional distribution of 5-HT2A receptors. These findings support the usefulness of [18F]altanserin as a radioligand for PET studies of 5-HT2A receptors.

Differential plasma endothelin levels in subgroups of patients with angina and angiographically normal coronary arteries. Coronary Artery Disease Research Group

BACKGROUND

Raised plasma endothelin concentrations have previously been reported in patients with cardiac syndrome X, but it is not known whether these levels vary between clinically distinct subgroups in this heterogeneous condition.

METHODS AND RESULTS

We compared plasma immunoreactive endothelin levels in 54 patients with angina pectoris and normal coronary angiograms and 21 healthy control subjects. The patient group was divided into 4 clinically distinct subgroups: 7 with left bundle branch block (group A); 7 with previous myocardial infarction (group B); 24 with positive exercise electrocardiography (group C); and 16 with negative exercise electrocardiography (group D). The plasma endothelin concentration was significantly higher in patients compared with control subjects (3.7 [2.9 to 4.3] vs 2.96 [2.4 to 3.4] pg/mL, respectively, median [interquartile range]; P=0.002). Endothelin concentrations were most significantly elevated in group A and group B (4.5 [3.6 to 5.2] pg/mL; P=0.005 and 4.1 [3.9 to 4.5] pg/mL; P=0.001, respectively). Plasma endothelin concentrations were also significantly elevated in group C (3.7 [2.8 to 4.1] pg/mL; P=0.02) but not in group D (3.0 [2.5 to 3.8] pg/mL; P=0.3).

CONCLUSIONS

Plasma endothelin concentration is elevated in patients with angina pectoris and angiographically normal coronary arteries, particularly those with left bundle branch block or previous myocardial infarction.