An adaptive view of caste differentiation in the neotropical wasp Polybia (Trichothorax) sericea Olivier (Hymenoptera: Vespidae)

The tribe Epiponini comprehends the swarm-founding Neotropical wasps, with several species endemic to Brazil, which are extremely important in studies of social evolution of wasps. The Epiponini diverge in several ways from the definitions of high eusociality, since caste syndromes range from species without morphological caste differentiation to those with complete caste dimorphism, and all species are polygynous. Frequently, indirect studies based on morphometry and physiology are the only solutions to collect data regarding the natural history and caste system in this tribe, since most species are extremely aggressive and build enveloped nests, usually in places of difficult access. We analyzed morphological parameters in seven colonies of the Epiponini species Polybia (Trichothorax) sericea Olivier in different phases of colonial development. Nine body variables were taken and females were classified according to their ovary development and spermathecal contents. The results showed that caste differences in this species are based on a contrast among variables: queens have larger mesosoma and abdomen, but are smaller in head width and wing length. These results suggest that morphological caste differentiation in this species is based mainly on body shape. We considered this combination of characters as being adaptive. We also showed that caste differences varied according to the colony cycle, with more conspicuous differences when queen number is reduced.

A novel tetracycline labeling schedule for longitudinal evaluation of the short-term effects of anabolic therapy with a single iliac crest bone biopsy: early actions of teriparatide

We describe a quadruple tetracycline labeling method that allows longitudinal assessment of short-term changes in bone formation in a single biopsy. We show that 1 month of hPTH(1-34) treatment extends the bone-forming surface, increases mineral apposition rate, and initiates modeling-based formation.

INTRODUCTION

Iliac crest biopsy, with histomorphometric evaluation, provides important information about cellular activity in bone. However, to obtain longitudinal information, repeat biopsies must be performed. In this study, we show the capability to obtain short-term longitudinal information on bone formation in a single biopsy using a novel, quadruple labeling technique.

MATERIALS AND METHODS

Two tetracycline labels were administered using a standard 3 days on, 12 days off, 3 days on format. Four weeks later, the tetracycline labeling was repeated using the same schedule but with a different tetracycline that can be distinguished from the first by its color under fluorescent light. Iliac crest biopsies were performed 1 week later and prepared undecalcified for histomorphometry. Indices of bone formation 1 month apart were measured and calculated using the two sets of labels. We used this method to investigate the early effects of teriparatide [hPTH(1-34)] treatment on bone formation. The results were compared with those from a group of control subjects who were quadruple-labeled, but did not receive hPTH(1-34).

RESULTS

Treatment with hPTH(1-34) dramatically stimulated bone formation on cancellous and endocortical surfaces. This was achieved by both an increase in the linear rate of matrix apposition and extension of the bone-forming surface. New bone was deposited on previously quiescent surfaces (i.e., modeling-based formation), but a proportion of this could occur by encroachment from adjacent resorption cavities.

CONCLUSIONS

A single transiliac crest bone biopsy, after sequential administration of two sets of tetracycline labels is a useful approach to study the short-term effects of anabolic agents on human bone. One month of hPTH(1-34) treatment extends the bone-forming surface, increases mineral apposition rate, and initiates modeling-based formation.

Short-term effects of estrogen, tamoxifen and raloxifene on hemostasis: a randomized-controlled study and review of the literature

INTRODUCTION

Estrogen therapy (ET), tamoxifen and raloxifene are associated with a two- to three-fold increased risk of venous thrombosis (VT); however, the mechanisms by which each drug increases venous thrombosis propensity are not fully understood. The objectives of this investigation were to compare the effects of these three treatments on hemostasis in a head to head randomized placebo-controlled trial.

PATIENTS/METHODS

Ninety-four postmenopausal women were assigned to receive oral estrogen (conjugated equine estrogen [CEE] 0.625 mg, n=23), tamoxifen 20 mg (n=24), raloxifene 60 mg (n=24) or placebo (n=23) daily for 6 months. Blood samples were analyzed for procoagulant factors (prothrombin, factors VII [fVII], VIII [fVIII], IX [fIX] and XI [fXI], D-dimer and von Willebrand factor [vWf]), anticoagulant factors (antithrombin [AT], total and free protein S, protein C and activated protein C [APC] resistance) and fibrinolytic factors (thrombin activatable fibrinolysis inhibitor [TAFI] and plasminogen activator inhibitor-1 [PAI-1]), at baseline and at 6 months of treatment.

RESULTS

Estrogen increased factor VII and D-dimer, and decreased antithrombin, total and free protein S and PAI-1. Changes with tamoxifen were distinct from estrogen with increases in factors VIII, IX, vWf and free protein S, and decreases in AT, total protein S, protein C and plasminogen activator inhibitor-1. Raloxifene produced similar effects as tamoxifen, but did not increase factor IX or decrease protein C.

CONCLUSIONS

Estrogen, tamoxifen and raloxifene affected hemostasis favoring procoagulation and impairing anticoagulation. The biochemical effects of the selective estrogen receptor modulators (SERMs) were distinct from those of estrogen and differed only subtly from each other.

Cellular and functional defects in a mouse model of heart failure

Heart failure and dilated cardiomyopathy develop in mice that lack the muscle LIM protein (MLP) gene (MLP(-/-)). The character and extent of the heart failure that occurs in MLP(-/-) mice were investigated using echocardiography and in vivo pressure-volume (P-V) loop measurements. P-V loop data were obtained with a new method for mice (sonomicrometry) using two pairs of orthogonal piezoelectric crystals implanted in the endocardial wall. Sonomicrometry revealed right-shifted P-V loops in MLP(-/-) mice, depressed systolic contractility, and additional evidence of heart failure. Cellular changes in MLP(-/-) mice were examined in isolated single cells using patch-clamp and confocal Ca(2+) concentration ([Ca(2+)]) imaging techniques. This cellular investigation revealed unchanged Ca(2+) currents and Ca(2+) spark characteristics but decreased intracellular [Ca(2+)] transients and contractile responses and a defect in excitation-contraction coupling. Normal cellular and whole heart function was restored in MLP(-/-) mice that express a cardiac-targeted transgene, which blocks the function of beta-adrenergic receptor (beta-AR) kinase-1 (betaARK1). These data suggest that, despite the persistent stimulus to develop heart failure in MLP(-/-) mice (i.e., loss of the structural protein MLP), downregulation and desensitization of the beta-ARs may play a pivotal role in the pathogenesis. Furthermore, this work suggests that the inhibition of betaARK1 action may prove an effective therapy for heart failure.

PhTx4, a new class of toxins from Phoneutria nigriventer spider venom, inhibits the glutamate uptake in rat brain synaptosomes

We report the characterization of a new class of glutamate uptake inhibitors isolated from Phoneutria nigriventer venom. Glutamate transport activity was assayed in rat cerebrocortical synaptosomes by using [(3)H]-L-glutamate. PhTx4 inhibited glutamate uptake in a dose dependent manner. The IC(50) value obtained was 2.35+/-0.9 microg/ml which is in the observed range reported for glutamate uptake blockers. Tx4-7, one of PhTx4 toxins, showed the strongest inhibitory activity (50.3+/-0.69%, n=3).