Short-term effects of escitalopram on regional brain function in first-episode drug-naive patients with major depressive disorder assessed by resting-state functional magnetic resonance imaging

BACKGROUND

Most knowledge regarding the effects of antidepressant drugs is at the receptor level, distal from the nervous system effects that mediate their clinical efficacy. Using functional magnetic resonance imaging (fMRI), this study investigated the effects of escitalopram, a selective serotonin reuptake inhibitor (SSRI), on resting-state brain function in patients with major depressive disorder (MDD).

METHOD

Fourteen first-episode drug-naive MDD patients completed two fMRI scans before and after 8 weeks of escitalopram therapy. Scans were also acquired in 14 matched healthy subjects. Data were analyzed using the regional homogeneity (ReHo) approach.

RESULTS

Compared to controls, MDD patients before treatment demonstrated decreased ReHo in the frontal (right superior frontal gyrus), temporal (left middle and right inferior temporal gyri), parietal (right precuneus) and occipital (left superior occipital gyrus and right cuneus) cortices, and increased ReHo in the left dorsal medial prefrontal gyrus and left anterior lobe of the cerebellum. Compared to the unmedicated state, ReHo in the patients after treatment was decreased in the left dorsal medial prefrontal gyrus, the right insula and the bilateral thalamus, and increased in the right superior frontal gyrus. Compared to controls, patients after treatment displayed a ReHo decrease in the right precuneus and a ReHo increase in the left anterior lobe of the cerebellum.

CONCLUSIONS

Successful treatment with escitalopram may be associated with modulation of resting-state brain activity in regions within the fronto-limbic circuit. This study provides new insight into the effects of antidepressants on functional brain systems in MDD.

γ-Aminobutyric acid (GABA) signalling in human pancreatic islets is altered in type 2 diabetes

AIMS/HYPOTHESIS

γ-Aminobutyric acid (GABA) is a signalling molecule in the interstitial space in pancreatic islets. We examined the expression and function of the GABA signalling system components in human pancreatic islets from normoglycaemic and type 2 diabetic individuals.

METHODS

Expression of GABA signalling system components was studied by microarray, quantitative PCR analysis, immunohistochemistry and patch-clamp experiments on cells in intact islets. Hormone release was measured from intact islets.

RESULTS

The GABA signalling system was compromised in islets from type 2 diabetic individuals, where the expression of the genes encoding the α1, α2, β2 and β3 GABA(A) channel subunits was downregulated. GABA originating within the islets evoked tonic currents in the cells. The currents were enhanced by pentobarbital and inhibited by the GABA(A) receptor antagonist, SR95531. The effects of SR95531 on hormone release revealed that activation of GABA(A) channels (GABA(A) receptors) decreased both insulin and glucagon secretion. The GABA(B) receptor antagonist, CPG55845, increased insulin release in islets (16.7 mmol/l glucose) from normoglycaemic and type 2 diabetic individuals.

CONCLUSIONS/INTERPRETATION

Interstitial GABA activates GABA(A) channels and GABA(B) receptors and effectively modulates hormone release in islets from type 2 diabetic and normoglycaemic individuals.

Extractive fermentation for enhanced propionic acid production from lactose by Propionibacterium acidipropionici

An extractive fermentation process using an amine extractant and a hollow-fiber membrane extractor to selectively remove propionic acid from the fermentation broth was developed to produce propionate from lactose. Compared to the conventional batch fermentation, the extractive fermentation had a much higher productivity ( approximately 1 g/(L.h) or 5-fold increase), higher propionate yield (up to 0.66 g/g or more than 20% increase), higher final product concentration (75 g/L or higher), and higher product purity ( approximately 90%). Meanwhile, acetate and succinate productions in the extractive fermentation were significantly reduced. The improved fermentation performance can be attributed to the reduced product inhibition and a possible metabolic pathway shift to favor more propionic but less acetic and succinic acid production. The process was stable and gave consistent long-term performance over the 1. 5-month period studied. The effects of propionate concentration, pH, and amine content in the solvent on the extractive fermentation were also studied and are discussed in this paper.

Development of computational wear simulation of metal-on-metal hip resurfacing replacements

As one of the alternatives to traditional metal-on-polyethylene total hip replacements, metal-on-metal hip resurfacing prostheses demonstrating lower wear have been introduced for younger and more active patients during the past decade. However, in vitro hip simulator testing for the predicted increased lifetime of these surface replacements is time-consuming and costly. Computational wear modelling based on the Archard wear equation and finite element contact analysis was developed in this study for artificial hip joints and particularly applied to metal-on-metal resurfacing bearings under simulator testing conditions to address this issue. Wear factors associated with the Archard wear equation were experimentally determined and based on the short-term hip simulator wear results. The computational wear simulation was further extended to a long-term evaluation up to 50 million cycles assuming that the wear rate stays constant. The prediction from the computational model shows good agreement with the corresponding simulator study in terms of volumetric wear and the wear geometry. The simulation shows the progression of linear wear penetrations, and the complexity of contact stress distribution on the worn bearing surfaces. After 50 million cycles, the maximum linear wear was predicted to be approximately 6 and 8 microm for the cup and head, respectively, and no edge contact was found.

Striatal neuronal loss or dysfunction and choline rise in children with attention-deficit hyperactivity disorder: a 1H-magnetic resonance spectroscopy study

Twelve previously untreated boys suffering from attention-deficit hyperactivity disorder (ADHD) were investigated by using proton magnetic resonance spectroscopy (1H MRS) before and after one dose (10 mg) of methylphenidate. Pre- and post-methylphenidate spectra were acquired bilaterally in the globus pallidus. Peaks of N-acetylaspartate (NAA), choline (Cho), myo-inositol, glutamate and creatine (Cr) were measured and the ratios of the peaks were calculated and compared with data from ten matched controls. In children having ADHD, NAA/Cr ratio decreased significantly in the bilateral striatum while Cho/Cr ratio showed a mild unilateral increase. One oral dose of methylphenidate did not affect the ratios significantly. These findings suggest that the striatum was bilaterally involved in pediatric ADHD patients. Approximately 20-25% of neurons may have died or may be severely dysfunctional. There seems to be a mild hyperactivity of the cholinergic system.

BACH1 is a DNA repair protein supporting BRCA1 damage response

The link between defects in BRCA1 and breast cancer development may be best understood by deciphering the role of associated proteins. BRCA1 associated C-terminal helicase (BACH1) interacts directly with the BRCA1 C-terminal BRCT repeats, which are important for BRCA1 DNA repair and are mutated in the majority of BRCA1 familial cancers. Thus, BACH1 is a likely candidate for mediating BRCA1 DNA repair and tumor suppression functions. Although previous evidence using overexpression of a dominant negative BACH1 has suggested that BACH1 is involved in BRCA1-DNA repair function, our results using BACH1 deficient cells provide direct evidence for involvement of BACH1 in DNA repair as well as for localizing BRCA1. Following DNA damage BACH1 is modified by phosphorylation, displays a BRCA1-like nuclear foci pattern and colocalizes with gamma-H2AX. Given that the BACH1/BRCA1 complex is unaltered by DNA damage and the intensity of BRCA1 foci is diminished in BACH1 deficient cells, BACH1 may serve to not only facilitate DNA repair, but also maintain BRCA1 in DNA damage foci.

Hypermethylation of the nel-like 1 gene is a common and early event and is associated with poor prognosis in early-stage esophageal adenocarcinoma

The nel-like1 (NELL1) gene maps to chromosome 11p15, which frequently undergoes loss of heterozygosity in esophageal adenocarcinoma (EAC). NELL1 promoter hypermethylation was examined by real-time methylation-specific polymerase chain reaction in 259 human esophageal tissues. Hypermethylation of this promoter showed highly discriminative receiver-operator characteristic curve profiles, clearly distinguishing esophageal squamous cell carcinoma (ESCC) and EAC from normal esophagus (NE) (P<0.001). NELL1 normalized methylation values were significantly higher in Barrett's metaplasia (BE), dysplastic Barrett's (D) and EAC than in NE (P<0.0000001). NELL1 hypermethylation frequency was zero in NE but increased early during neoplastic progression, to 41.7% in BE from patients with Barrett's alone, 52.5% in D and 47.8% in EAC. There was a significant correlation between NELL1 hypermethylation and BE segment length. Three (11.5%) of 26 ESCCs exhibited NELL1 hypermethylation. Survival correlated inversely with NELL1 hypermethylation in patients with stages I-II (P=0.0264) but not in stages III-IV (P=0.68) EAC. Treatment of KYSE220 ESCC and BIC EAC cells with 5-aza-2'-deoxycytidine reduced NELL1 methylation and increased NELL1 mRNA expression. NELL1 mRNA levels in EACs with an unmethylated NELL1 promoter were significantly higher than those in EACs with a methylated promoter (P=0.02). Promoter hypermethylation of NELL1 is a common, tissue-specific event in human EAC, occurs early during Barrett's-associated esophageal neoplastic progression, and is a potential biomarker of poor prognosis in early-stage EAC.

A narrow repertoire of transcriptional modules responsive to pyogenic bacteria is impaired in patients carrying loss-of-function mutations in MYD88 or IRAK4

Loss of function of the kinase IRAK4 or the adaptor MyD88 in humans interrupts a pathway critical for pathogen sensing and ignition of inflammation. However, patients with loss-of-function mutations in the genes encoding these factors are, unexpectedly, susceptible to only a limited range of pathogens. We employed a systems approach to investigate transcriptome responses following in vitro exposure of patients' blood to agonists of Toll-like receptors (TLRs) and receptors for interleukin 1 (IL-1Rs) and to whole pathogens. Responses to purified agonists were globally abolished, but variable residual responses were present following exposure to whole pathogens. Further delineation of the latter responses identified a narrow repertoire of transcriptional programs affected by loss of MyD88 function or IRAK4 function. Our work introduces the use of a systems approach for the global assessment of innate immune responses and the characterization of human primary immunodeficiencies.

Molecular characterization of a novel, developmentally regulated small embryonic chaperone from Caenorhabditis elegans

Low molecular weight chaperones inhibit protein aggregation and facilitate refolding of partially denatured polypeptides in cells subjected to physical and chemical stresses. The nematode Caenorhabditis elegans provides a system amenable for investigations on roles for chaperone proteins in normal homeostasis and development. We characterized a C. elegans gene and cDNAs that encode a novel, small embryonic chaperone-like protein (SEC-1) that is composed of 159 amino acids. The central core of SEC-1 (residues 45-126) is approximately 40% identical with a corresponding segment of mammalian Hsp27 and alphaB crystallin. Expression of SEC-1 in Escherichia coli confers thermotolerance on the bacterium. SEC-1 mRNA is evident only in C. elegans oocytes and developing embryos. Translation and accumulation of SEC-1 protein is temporally coupled with a prolonged burst of intense protein synthesis and rapid mitogenesis during early embryogenesis. As the rate of protein synthesis decreases during late embryogenesis, levels of SEC-1 and its cognate mRNA decline precipitously. Induction/deinduction of SEC-1 is precisely regulated by intrinsic developmental factors rather than extrinsic stresses. In vivo injection of C. elegans oocytes with antisense oligonucleotides that complement the 5'-end of SEC-1 mRNA arrests nematode development at an early stage after fertilization. Thus, SEC-1 appears to be adapted to perform essential functions in early embryogenesis.

Hip resurfacing arthroplasty: the evolution of contemporary designs

Metal-on-metal hip resurfacing is considered by many as the most significant recent development in hip arthroplasty. It preserves proximal femoral bone stock, optimizes stress transfer to the proximal femur, and offers inherent stability and optimal range of movement. The early results of hip resurfacing in the 1970s and 1980s were poor and the procedure was largely abandoned by the mid-1980s. The expectation that these prostheses would be easy to revise was not often fulfilled. The large diameter of the articulation combined with thin polyethylene cups or liners resulted in accelerated wear and the production of large volumes of biologically active particulate debris, leading to bone loss and implant loosening. Failure has been attributed to other factors, mainly avascular necrosis of the femoral head. However, this concern has not been confirmed by retrieval studies. The failure of early hip resurfacings was essentially a consequence of the use of inappropriate materials, poor implant design, inadequate instrumentation, and crude surgical technique. It was not an inherent problem with the procedure itself. The renaissance of metal-on-metal articulations for total hip arthroplasty enabled the introduction of new hip resurfacings and most of the major implant manufacturers have already introduced such systems. Early results are encouraging and complications commonly seen in the 1970s and 1980s, such as early implant loosening and femoral neck fracture, now appear to be rare. Whilst early results should be regarded with caution, modern metal-on-metal hip resurfacing potentially offers the ultimate bone preservation and restoration of function in appropriately selected young patients.

Neuroanatomical substrates of late-life minor depression. A quantitative magnetic resonance imaging study

OBJECTIVE

To examine the neuroanatomical correlates of late-life minor depression using magnetic resonance imaging.

DESIGN

Cross-sectional quantitative magnetic resonance imaging study of elderly patients with minor depression and age-matched controls.

SETTING

Patients and controls were recruited from the community through advertisements to the Section of Geriatric Psychiatry, University of Pennsylvania, Philadelphia.

PARTICIPANTS

Our sample included 18 subjects diagnosed as having minor depression using the modified Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, research criteria and 31 controls without depression. Patients were free of other central nervous system disease and both groups had comparable degrees of medical comorbidity.

MAIN OUTCOME MEASURES

All images were acquired on a 1.5-T scanner and absolute and normalized quantitative measures of global and focal brain and cerebrospinal fluid volumes were compared between groups.

RESULTS

Prefrontal lobe volume was significantly smaller in the group with minor depression (P = .002) compared with controls after controlling for age, sex, and age by sex interactions. More global measures of brain and cerebrospinal fluid volumes were comparable in both groups.

CONCLUSIONS

These data suggest that focal prefrontal atrophy may provide an important neuroanatomical substrate in late-life minor depression.

Radiative transfer in nonuniformly refracting layered media: atmosphere-ocean system

We have applied the discrete-ordinate method to solve the radiative-transfer problem pertaining to a system consisting of two strata with different indices of refraction. The refraction and reflection at the interface are taken into account. The relevant changes (as compared with the standard problem with a constant index of refraction throughout the medium) in formulation and solution of the radiative-transfer equation, including the proper application of interface and boundary conditions, are described. Appropriate quadrature points (streams) and weights are chosen for the interface-continuity relations. Examples of radiative transfer in the coupled atmosphere-ocean system are provided. To take into account the region of total reflection in the ocean, additional angular quadrature points are required, compared with those used in the atmosphere and in the refractive region of the ocean that communicates directly with the atmosphere. To verify the model we have tested for energy conservation. We also discuss the effect of the number of streams assigned to the refractive region and the total reflecting region on the convergence. Our results show that the change in the index of refraction between the two strata significantly affects the radiation field. The radiative-transfer model we present is designed for application to the atmosphere-ocean system, but it can be applied to other systems that need to consider the change in the index of refraction between two strata.

Combining tumor deposits with the number of lymph node metastases to improve the prognostic accuracy in stage III colon cancer: a post hoc analysis of the CALGB/SWOG 80702 phase III study (Alliance)☆

BACKGROUND

In colon cancer, tumor deposits (TD) are considered in assigning prognosis and staging only in the absence of lymph node metastasis (i.e. stage III pN1c tumors). We aimed to evaluate the prognostic value of the presence and the number of TD in patients with stage III, node-positive colon cancer.

PATIENTS AND METHODS

All participants from the CALGB/SWOG 80702 phase III trial were included in this post hoc analysis. Pathology reports were reviewed for the presence and the number of TD, lymphovascular and perineural invasion. Associations with disease-free survival (DFS) and overall survival (OS) were evaluated by multivariable Cox models adjusting for sex, treatment arm, T-stage, N-stage, lymphovascular invasion, perineural invasion and lymph node ratio.

RESULTS

Overall, 2028 patients were included with 524 (26%) TD-positive and 1504 (74%) TD-negative tumors. Of the TD-positive patients, 80 (15.4%) were node negative (i.e. pN1c), 239 (46.1%) were pN1a/b (<4 positive lymph nodes) and 200 (38.5%) were pN2 (≥4 positive lymph nodes). The presence of TD was associated with poorer DFS [adjusted hazard ratio (aHR) = 1.63, 95% CI 1.33-1.98] and OS (aHR = 1.59, 95% CI 1.24-2.04). The negative effect of TD was observed for both pN1a/b and pN2 groups. Among TD-positive patients, the number of TD had a linear negative effect on DFS and OS. Combining TD and the number of lymph node metastases, 104 of 1470 (7.1%) pN1 patients were re-staged as pN2, with worse outcomes than patients confirmed as pN1 (3-year DFS rate: 65.4% versus 80.5%, P = 0.0003; 5-year OS rate: 87.9% versus 69.1%, P = <0.0001). DFS was not different between patients re-staged as pN2 and those initially staged as pN2 (3-year DFS rate: 65.4% versus 62.3%, P = 0.4895).

CONCLUSION

Combining the number of TD and the number of lymph node metastases improved the prognostication accuracy of tumor-node-metastasis (TNM) staging.

A New Formulation for the Prediction of Polyethylene Wear in Artificial Hip Joints

Artificial joints employing ultra-high molecular weight polyethylene (UHMWPE) are widely used to treat joint diseases and trauma. Wear of the polymer bearing surface largely limits the use of these joints in younger and more active patients. Previous studies have shown the wear factor used in Archard's law for the conventional polyethylene to be highly dependent on contact pressure and this has produced variability in experimental data and has constrained the reliability and applicability of previous computational predictions. A new wear law is proposed, based on wear volume being dependent on, and proportional to, the product of the sliding distance and contact area. The dimensionless proportional constant, wear coefficient, which was independent of contact pressure, was determined from a multi-directional pin on plate study. This was used in computational predictions of the wear of the conventional UHMWPE hip joints. The wear of the polyethylene cup was independently experimentally determined in physiological full hip joint simulator studies. The predicted wear rate from the new computational model was generally increased, with an improved agreement with the experimental measurement compared with the previous computational model. It was shown that wear in the UHMWPE hip joints increased as head size and contact area increased. This resulted in a much larger increase in the wear rate as the head size increased, compared with the previous computational model, and is consistent with clinical observations. This new understanding of the wear mechanism in artificial joints using the UHMWPE bearing surfaces, and the improved ability to predict wear independently and to address previously described discrepancies offer new opportunities to optimize design parameters.

A low-power, atmospheric pressure, pulsed plasma source for molecular emission spectrometry

A low-power, plasma source-based, portable molecular emission detector is described in this paper. The detector employs a pulsed-plasma source operated at atmospheric pressure for molecular fragmentation and excitation. The plasma was generated with a home-built high-voltage pulsed power supply. The average operational power of the detector was less than 0.2 W. The effects of operational parameters such as plasma gas, voltage, and plasma gas flow rate were investigated. Molecular emission spectra of a variety of organic compounds were studied. The features of the emission spectra obtained with the pulsed plasma source were significantly different from those obtained with direct current (dc) discharge at a power higher than 10 W. The spectra obtained in this work showed strong CH emission at 431.2 nm; however, the typical CN emission observed with a conventional dc plasma source at 383-388 nm was very weak in most cases. The strong CN emission was only obtained for compounds containing nitrogen, such as aniline. Dimethyl sulfoxide can be detected at a limit of 200 ppb using helium plasma by observing the emission band of the CH radical. The detector was very stable and did not experience electrode fouling even with the introduction of organic vapors. Such a detector is very promising for organic vapor detection.

The initial stability and contact mechanics of a press-fit resurfacing arthroplasty of the hip

Finite element analysis was used to examine the initial stability after hip resurfacing and the effect of the procedure on the contact mechanics at the articulating surfaces. Models were created with the components positioned anatomically and loaded physiologically through major muscle forces. Total micromovement of less than 10 μm was predicted for the press-fit acetabular components models, much below the 50 μm limit required to encourage osseointegration. Relatively high compressive acetabular and contact stresses were observed in these models. The press-fit procedure showed a moderate influence on the contact mechanics at the bearing surfaces, but produced marked deformation of the acetabular components. No edge contact was predicted for the acetabular components studied.

It is concluded that the frictional compressive stresses generated by the 1 mm to 2 mm interference-fit acetabular components, together with the minimal micromovement, would provide adequate stability for the implant, at least in the immediate post-operative situation.

The role of the surface amorphous layer of articular cartilage in joint lubrication

Articular cartilage is a complex soft tissue that performs multiple functions in the joint. In particular, the amorphous layer that covers the surface of articular cartilage is thought to play some role in lubrication. This study aimed to characterize the surface amorphous layer (SAL) using a variety of techniques, including environmental scanning electron microscopy, transmission electron microscopy, white light interferometry, and biochemical analysis of its composition. Friction tests were conducted to investigate the role of the SAL in lubrication. A protocol to remove successfully the SAL without damaging the underlying cartilage was developed and the material removed from healthy cartilage was found to contain approximately equal quantities of glycosaminoglycan (GAG), protein, and lipid. Cartilage-on-cartilage friction tests were conducted on fresh, healthy cartilage with and without the SAL, under both dynamic and static operating conditions. Removal of the SAL was not found to change the friction coefficient. However, subsequent staining of specimens indicated that the SAL had replenished during the test following loading. The replenished SAL was characterized and found to contain lipids and sulphated GAGs with undetectable protein. This study revealed experimental evidence of surface layer replenishment in articular cartilage. It was postulated that the surface layer regeneration mechanism was purely mechanical and associated with movement of GAGs and lipids through the cartilage matrix during deformation, since the experimental set-up did not contain any means of biochemical activation.

Effects of lysine intake during late gestation and lactation on blood metabolites, hormones, milk composition and reproductive performance in primiparous and multiparous sows

Modern genotype primiparous and multiparous sows (Yorkshire x Landrace, n=48) were used to evaluate effects of dietary lysine intake during late gestation and lactation, and their interaction on reproductive performance. Sows were randomly allotted to two gestation lysine (G, 0.6% or 0.8% lysine) treatments based on parity in a 2 x 2 factorial arrangement, and each treatment had 12 replicates comprising 1 sow. Then all the sows were assigned to two lactation lysine (L, 1.0% or 1.3% lysine) treatments within parity and gestation treatments in a 2 x 2 x 2 factorial design, and each treatment comprised six replicates with 1 sow/replicate during lactation. Feeding higher lysine level during gestation increased sow body weight and backfat thickness (P=0.001) and body condition was better (P=0.001) in multiparous than that of primiparous sows. Both of the lysine levels during lactation and parity influenced sow body condition and reproductive performance (P<0.05). Higher lysine intake during lactation increased the concentrations of total solids (P=0.024), protein (P=0.001) and solids not-fat (P=0.042) in colostrum and total solids (P=0.001), protein (P=0.001), fat (P=0.001) and solids not-fat (P=0.005) in milk. Protein concentration of milk was greater (P=0.001) in multiparous sows than that of primiparous sows. Feeding of high lysine diets resulted in an increment of plasma urea N (P=0.010; P=0.047) and a decrease of creatinine (P=0.045; P=0.002) on the day of postfarrowing and weaning, respectively. Furthermore, as lysine intake increased, the secretions of insulin, FSH, and LH were increased (P<0.05) and multiparous sows showed higher (P<0.05) concentrations of FSH and LH pulses on the day of postfarrowing and weaning, respectively. These results indicated that higher lysine intake than that recommended by NRC [NRC, 1998. Nutrient Requirements of Swine, 10th ed. National Academy Press, 458 Washington, DC] could improve sow performance during late gestation and lactation. Furthermore primiparous sows need higher lysine intake than multiparous sows. Moreover, nutritional impacts on reproduction may be mediated in part through associated effects on circulating LH concentration.