Effects of gonadal steroids on reward circuitry function and anhedonia in women with a history of postpartum depression.

BACKGROUND: Reward system dysfunction is evident across neuropsychiatric conditions. Here we present data from a double-blinded pharmaco-fMRI study investigating the triggering of anhedonia and reward circuit activity in women. METHODS: The hormonal states of pregnancy and parturition were simulated in euthymic women with a history of postpartum depression (PPD+; n = 15) and those without such a history (PPD-; n = 15) by inducing hypogonadism, adding back estradiol and progesterone for 8 weeks ("addback"), and then withdrawing both steroids ("withdrawal"). Anhedonia was assessed using the Inventory of Depression and Anxiety Symptoms (IDAS) during each hormone phase. Those who reported a 30 % or greater increase in IDAS anhedonia, dysphoria, or ill temper during addback or withdrawal, compared with pre-treatment, were identified as hormone sensitive (HS+) and all others were identified as non-hormone sensitive (HS-). The monetary incentive delay (MID) task was administered during fMRI sessions at pre-treatment and during hormone withdrawal to assess brain activation during reward anticipation and feedback. RESULTS: On average, anhedonia increased during addback and withdrawal in PPD+ but not PPD-. During reward feedback, both HS+ (n = 10) and HS- (n = 18) showed decreased activation in clusters in the right putamen (p < .031, FWE-corrected) and left postcentral and supramarginal gyri (p < .014, FWE-corrected) at the withdrawal scans, relative to pre-treatment scans. LIMITATIONS: A modest sample size, stringent exclusion criteria, and relative lack of diversity in study participants limit the generalizability of results. CONCLUSION: Although results do not explain differential hormone sensitivity in depression, they demonstrate significant effects of reproductive hormones on reward-related brain function in women.

Unilateral electronegative ERG of non-vascular aetiology.

BACKGROUND: Full field and pattern electroretinograms (ERG, PERG) are performed to assess generalised retinal function and macular function, respectively. An (electro) negative full field ERG usually describes an ISCEV standard maximal response in which the b-wave is smaller than a normal or minimally reduced a-wave and indicates dysfunction that is post-phototransduction. The most common cause of a unilateral negative ERG is central retinal artery occlusion (CRAO) or birdshot chorioretinopathy (BCR). This study examines the clinical and electrophysiological features of patients with unilateral negative ERG who do not have CRAO or BCR. METHODS: 12 patients were ascertained with a unilateral negative ERG in whom a vascular aetiology and BCR were excluded. Most presented with symptoms of central retinal dysfunction. In 11 of the 12 patients additional long duration photopic stimuli were used to test cone system ON and OFF responses. RESULTS: All 12 patients had unilateral electronegative bright flash full field ERGs indicating total or relative preservation of rod photoreceptor function, but dysfunction post-phototransduction. Seven of these patients had non-specific inflammatory changes in the eye with the negative ERG. Six patients, including five with inflammatory signs, had involvement of the cone ON response with complete preservation of cone OFF responses. A further three patients showed evidence of cone ON response abnormality with less severe OFF response involvement. CONCLUSION: The ERGs in this heterogeneous group of patients predominantly showed post-phototransduction involvement of the ON pathways. Sparing of the cone OFF response was often observed. The majority of patients had signs of previous inflammation and it is speculated that these highly unusual unilateral changes may be mediated via an autoimmune mechanism.

Genetic and phenotypic variance and covariance components for feed intake, feed efficiency, and other postweaning traits in Angus cattle.

Records on 1,180 young Angus bulls and heifers involved in performance tests were used to estimate genetic and phenotypic parameters for feed intake, feed efficiency, and other postweaning traits. The mean age was 268 d at the start of the performance test, which comprised 21-d adjustment and 70-d test periods. Traits studied included 200-d weight, 400-d weight, scrotal circumference, ultrasonic measurements of rib and rump fat depths and longissimus muscle area, ADG, metabolic weight, daily feed intake, feed conversion ratio, and residual feed intake. For all traits except the last five, additional data from the Angus Society ofAustralia pedigree and performance database were included, which increased the number of animals to 27,229. Genetic (co)variances were estimated by REML using animal models. Direct heritability estimates for 200-d weight, 400-d weight, rib fat depth, ADG, feed conversion,and residual feed intake were 0.17 +/- 0.03, 0.27 +/- 0.03, 0.35 +/- 0.04, 0.28 +/- 0.04, 0.29 +/- 0.04, and 0.39 +/- 0.03, respectively. Feed conversion ratio was genetically (r(g) = 0.66 ) and phenotypically (r(p) = 0.53) correlated with residual feed intake. Feed conversion ratio was correlated (r(g) = -0.62, r(p) = -0.74) with ADG, whereas residual feed intake was not (rg = -0.04, r(p) = -0.06). Genetically, both residual feed intake and feed conversion ratio were negatively correlated with direct effects of 200-d weight (r(g) = -0.45 and -0.21) and 400-d weight (r(g) = -0.26 and -0.09). The correlations between the remaining traits and the feed efficiency traits were near zero, except between feed intake and feed conversion ratio (r(g) = 0.31, r(p) = 0.23), feed intake and residual feed intake (r(g) = 0.69, r(p) = 0.72), and rib fat depth and residual feed intake (r(g) = 0.17, r(p) = 0.14). These results indicate that genetic improvement in feed efficiency can be achieved through selection and, in general, correlated responses in growth and the other postweaning traits will be minimal.

Primary vitrectomy for rhegmatogenous retinal detachment: an analysis of failure.

PURPOSE: To find the cause of failure in primary vitrectomy for rhegmatogenous retinal detachment. METHODS: Retrospective review of 171 consecutive cases of RRD treated by primary pars plana vitrectomy (PPV) from a tertiary referral centre to identify the 25 cases in which surgery had failed. Detachments with giant or macula breaks at initial presentation, with proliferative diabetic retinopathy or with PVR greater than grade B were excluded. RESULTS: The failure rate after the first operation was 14.6% and the commonest cause of failure was missed retinal breaks, accounting for 64.3% of failures. CONCLUSION: Missed retinal breaks are the commonest cause of failure of primary PPV for RRD although proliferative vitreoretinopathy may contribute to surgical failure. This re-emphasises the importance of assiduous peroperative retinal examination.

Is hyaluronidase helpful for peribulbar anaesthesia?

A prospective, randomised controlled study was performed to investigate whether hyaluronidase improved the efficacy of peribulbar anaesthesia. Ninety-two patients undergoing peribulbar anaesthesia for intraocular surgery all received 10 ml of an anaesthetic solution consisting of a 50:50 mixture of 2% lignocaine with 1 in 200,000 adrenaline and 0.5% bupivacaine. Patients were randomised to a hyaluronidase group which received 150 IU/ml hyaluronidase in this anaesthetic solution (a higher concentration than previous studies) or a control group which received no hyaluronidase. There were 44 patients in the hyaluronidase group and 48 patients in the control group. All anaesthetic injections were administered by an experienced ophthalmologist and no supplementary injections were required in any case. The mean time interval between administration of the block and commencement of surgery was 22 minutes. No statistically significant difference was found between the two groups for pre-operative akinesia (p = 0.16), intraoperative akinesia (p = 0.25), eyelid paralysis (p = 0.72), objective analgesia (p = 0.23) or subjective analgesia (p = 0.60). The majority of patients in both groups achieved excellent akinesia, eyelid paralysis and analgesia. The reasons for these findings in the light of previously conflicting reports on the value of hyaluronidase in peribulbar anaesthesia are discussed.

Studies on the topography of the catalytic site of acetylcholinesterase using polyclonal and monoclonal antibodies.

Polyclonal and monoclonal antibodies were generated against a synthetic peptide (25 amino acid residues) corresponding to the amino acid sequence surrounding the active site serine of Torpedo californica acetylcholinesterase (AChE). Prior to immunization, the peptide was either coupled to bovine serum albumin or encapsulated into liposomes containing lipid A as an adjuvant. To determine whether this region of AChE is located on the surface of the enzyme and thus accessible for binding to antibodies, or located in a pocket and thus not accessible to antibodies, the immunoreactivity of the antibodies was determined using enzyme-linked immunosorbent assay (ELISA), immunoprecipitation, Western blots, and competition ELISA. The polyclonal antibody and several of the monoclonal antibodies failed to react with either Torpedo or fetal bovine serum AChE in their native conformations, but showed significant cross-reactivity with the denatured enzymes. Human serum butyrylcholinesterase, which has a high degree of amino acid sequence homology with these AChEs, failed to react with the same antibodies in either native form or denatured form. Chymotrypsin also failed to react with the monoclonal antibodies in either form. Eighteen octapeptides spanning the entire sequence of this region were synthesized on polyethylene pins, and epitopes of representative monoclonal antibodies were determined by ELISA. The reactivity of peptides suggest that a portion of the 25 mer peptide in AChE containing the active site serine is the primary epitope. It is not exposed on the surface of the enzyme and is most likely sequestered in a pocket-like conformation in the native enzyme.

Radioprotective effects of lipid A, liposomes, and liposomes containing lipid A in mice.

Lipid A from Gram-negative bacterial lipopolysaccharide (endotoxin) was incorporated into liposomal membranes and examined as a prophylactic radioprotectant compound in lethally irradiated mice. Splenic hematopoietic activity, resulting in increased numbers of spleen cell colonies, was induced both by lipid A alone or more strongly by liposomal lipid A. Increased survival of lethally irradiated animals was induced to a slight extent by liposomes alone, to a greater extent by lipid A, and at the highest level by liposomes containing lipid A. Under conditions where 100% of untreated or saline-treated animals died of acute radiation syndrome after 20 days, more than 90% of the animals pretreated with liposomal lipid A were still alive 30 days after irradiation. We conclude that lipid A had substantial radioprotectant activity by itself, and the activity was enhanced by incorporation into liposomes. Liposomes alone also exhibited mild radioprotectant effects.

Specific binding of concanavalin A to free inositol and liposomes containing phosphatidylinositol.

We previously reported that concanavalin A could bind specifically to liposomes containing phospholipids and lacking glycoconjugates (Biochem. Biophys. Res. Comm. 74, 208, 1977). In the present study we show that the binding of concanavalin A to the liposomes was greatly increased (up to 5 fold) by the presence of phosphatidylinositol in the liposomes. Furthermore, the binding of concanavalin A to phosphatidylinositol-liposomes was specific and could be inhibited by either alpha-methyl mannoside or by myo-inositol. We also found that concanavalin A-induced lymphocyte mitogenesis could be inhibited either by alpha-methyl mannoside or by myo-inositol. Simultaneous addition of both inhibitors to concanavalin A and liposomes showed that inhibition was non-competitive: alpha-methyl mannoside was more inhibitory to liposomes lacking phosphatidylinositol, and myo-inositol was more inhibitory to liposomes containing phosphatidylinositol. This suggests that the binding site for inositol might be different than that for mannose. Equilibrium dialysis and Scatchard plots revealed 4 binding sites each for inositol and mannose at neutral pH. The binding constants of concanavalin A were 0.13 X 10(4) and 0.25 X 10(4) liters/mole respectively for inositol and mannose. We conclude that concanavalin A binds specifically to the inositol portion of phosphatidylinositol.

Mitogenic activities of lipid A and liposome-associated lipid A: effects of epitope density.

Among eight purified lipid A fractions, there was heterogeneity of mitogenic activity, but the relative activity could not be predicted by limulus amebocyte lysate assay. Analysis of mitogenic activity after the incorporation of lipid A into liposomes demonstrated that epitope density of lipid A was a crucial factor that strongly modulated expression of lipid A. The results suggest that lipid A hydrophobic groups are responsible for mitogenic activity and that the surface accessibility of lipid A hydrophobic groups in membranes may be influenced by epitope density. The data are compared with previous results derived from parallel studies on limulus amebocytes. Both approaches lead to the conclusion that the activities of purified lipid A fractions are heterogeneous and that epitope density is critically important for the expression of biologic activity of membrane-associated lipid A.

Mitogenic response of lymphocytes from C3H/HeJ mice in the presence of lipid A and lipid A fractions.

Purified lipid A and eight fractions of lipid A were examined for the ability to elicit a mitogenic response in spleen lymphocytes of endotoxin-resistant C3H/HeJ mice. The pattern of results obtained with different lipid A fractions was similar to that observed with spleen cells from the endotoxin-responsive C57Bl/6J mouse. Although the absolute mitogenic response of C3H/HeJ lymphocytes to lipid A was diminished, the cells apparently were completely normal with respect to the pattern of relative mitogenic responses induced by purified fractions of lipid A.

Enhancement by lipid A of mucosal immunogenicity of liposome-associated cholera toxin.

Two methods that might enhance the mucosal immunogenicity of a protein antigen, cholera toxin (CT), were studied in rats: association of CT with liposomes, and coadministration of CT with lipid A. Enteric priming by CT was not enhanced when the antigen was trapped within liposomes or bound to their surface via GM1 ganglioside, nor was it improved when CT was mixed with lipid A or with liposomes containing lipid A. However, lipid A did enhance priming by liposome-associated CT when the lipid A was incorporated into CT-bearing liposomes. It is concluded that lipid A can act as an adjuvant for a local IgA response to a mucosally applied antigen, at least when lipid A and the antigen are associated on a liposome carrier.

Suppression of phagocytic function and phospholipid metabolism in macrophages by phosphatidylinositol liposomes.

Increased phagocytosis of complement-opsonized vesicles was accompanied by increased phosphatidylinositol (PtdIns) turnover in murine macrophages. However when PtdIns was also present as one of the lipids in the opsonized liposomes, it reduced both phagocytosis and stimulation of endogenous PtdIns turnover. These suppressive effects did not occur with liposomes containing PtdIns phosphate (PtdIns-P). When a monoclonal IgM "anti-PtdIns-P" antibody that bound to inositol phosphate was substituted for antigalactosyl ceramide antibodies for activating complement in the opsonizing process, enhanced phagocytosis occurred normally but increased cellular PtdIns turnover did not occur. Therefore the data show that, although PtdIns-P cannot replace PtdIns for suppressing PtdIns turnover, PtdIns-P can be induced to be suppressive after specific binding to an antibody that recognizes inositol phosphate. We conclude that ingestion of complement-opsonized liposomes by macrophages and complement-induced turnover of cellular PtdIns are separate but related phenomena that can be independently modulated by the polar group of liposomal PtdIns.

Effects of negatively charged lipids on phagocytosis of liposomes opsonized by complement.

Ingestion of liposomes opsonized by specific antibody plus complement was investigated in vitro. Although the antibodies alone (IgM) did not have an opsonizing effect, in the presence of such antibodies uptake and ingestion of liposomes by mouse peritoneal macrophages was enhanced 5- to 10-fold by addition of complement. Phagocytosis of complement-opsonized liposomes was strongly dependent on the charge of the liposomal lipids. The presence of a negatively charged (i.e., acidic) lipid profoundly suppressed the uptake of the liposomes. Each of three acidic liposomal lipids, phosphatidylserine, phosphatidylinositol and dicetyl phosphate, suppressed liposome uptake. We conclude that opsonization of liposomes with complement greatly stimulates ingestion of liposomes by murine macrophages. However, most of the opsonic enhancement conferred by complement can be prevented by the presence of negatively charged membrane lipids.

Interactions of lipid a and liposome-associated lipid A with Limulus polyphemus amoebocytes.

Lipid A or lipid A fractions and liposomes containing lipid A were tested for the ability to gel Limulus amoebocyte lysates and for effects on intact Limulus amoebocytes. Liposomes having a relatively low concentration of lipid A did not produce coagulation of lysate and were designated as Limulus-negative, but liposomes having a high concentration of lipid A were Limulus-positive. Limulus-negative liposomes had no effect on intact amoebocytes. Limulus-positive liposomes caused a striking transformation in the appearance of amoebocytes in that the cells sent out long filamentous extensions that formed a tangled network of processes between cells. The filamentous projections were similar to those that have been previously observed in the presence of gram-negative bacteria. We conclude that amoebocytes have the ability to recognize Limulus-positive liposomes, but the lack of activation of Limulus lysate or the absence of amoebocyte recognition does not prove the absence of liposomal lipid A. We also found that individual lipid A fractions were heterogeneous in their ability to gel lysate. Of eight fractions tested, one (fraction 1) had no detectable activity above the background, and the seven others had activity that ranged from 10-fold to 10,000-fold above the background. The heterogeneity of lipid A fractions detected in assays with amoebocyte lysate was consistent with the finding of heterogeneity in other functional assays of lipid A fractions.