On the Morphology of the Synaptic Vesicles of the Axospine Synapses in the Rat Visual Cortex

An electron-microscopoical Observationof the shape and form of the synapticvesicles in the axospine synapses of therat visual cortex fixed with glutaralde-hyde and postfixed with osmium tetro-xide is reported.Each axospine synapse in the visualcortex consists of a presynaptic boutonwith a dendritic spine from which it is     

Charming the mosquito: do malaria symptoms increase the attractiveness of the host for the vector?

The two week period that stretches between the absorption of gametocytes from a malaria patient by a mosquito and the subsequent injection of sporozoites in another human host is a most fragile segment of the malaria cycle. There is non-randomness in the blood meal choice of anopheline vectors. Manipulations of the host by the parasite to satisfy the preferences of the vector might have contributed to the robustness of the malaria cycle. Indeed, although gametocytes do not directly cause symptoms, the acute and chronic clinical manifestations caused by asexual forms seem to be organized around their transmission: fever patterns and behavior modification, anemia and thrombocytopenia converge towards making malarious individuals a preferred and safer source of blood for the vector than non-malarious individuals. Malaria symptoms offer the vector its favorite cues: increased skin temperature, increased lactates, sweating, and CO(2) expiration. In addition, this tempting menu seems easier to absorb because of thrombocytopenia and reduced blood viscosity during anemia, and because behavior modification reduces mosquito avoidance and the risk of dying. The attractive cues may be characteristic symptoms of malaria but also slight infraclinical changes that mostly go unnoticed by the doctor but not by the vector. The manifestations of malaria are often seen as adaptive for the host, this article argues that on average they may also be adaptive for malaria parasites. Examining malaria as the extended phenotype of Plasmodium leads to new research questions.     

Should the position of the patellar component replicate the vertical median ridge of the native patella?

Background

In total knee arthroplasty (TKA), the position of the patellar component can affect patellar tracking. However, the patellar component cannot always replicate the original high point of the patella because of anatomical variance. This study investigated whether altering the highest point of the patella can affect outcomes of primary TKA, especially in patients having a patella with a far-medialized median ridge.

Can the sex of the second child be predicted by the birth-weight of the first child?

The reproduction costs to a human mother are different if she has a son as opposed to a daughter. According to the Trivers-Willard hypothesis, evolution should promote those females who, having the ability to invest in the more expensive sex, are also able to adjust the sex of their offspring accordingly. It is therefore possible that a mother's biological condition (which is also connected with her reproductive potential), as measured by the neonatal weight of her first child, can be a good predictor of the second child's sex. From data for 227 healthy mothers from Wroclaw (Poland) we show that the probability of giving birth to a boy in the second pregnancy is higher after a relatively heavier first-born child (ANOVA, F(1,225)=3.79, P<0.053). This relationship, however, is only significant after a first-born daughter (F(1,117)=9.66, P<0.002) and not after a first-born boy. Some possible explanations of the fact that only the birth-weight of a first-born daughter--and not a son--can be a good predictor of the secondary sex ratio are also discussed.     

Centrosomes in the DNA damage response—the hub outside the centre

Here, we review how DNA damage affects the centrosome and how centrosomes communicate with the DNA damage response (DDR) apparatus. We discuss how several proteins of the DDR are found at centrosomes, including the ATM, ATR, CHK1 and CHK2 kinases, the BRCA1 ubiquitin ligase complex and several members of the poly(ADP-ribose) polymerase family. Stereotypical centrosome organisation, in which two centriole barrels are orthogonally arranged in a roughly toroidal pericentriolar material (PCM), is strongly affected by exposure to DNA-damaging agents. We describe the genetic dependencies and mechanisms for how the centrioles lose their close association, and the PCM both expands and distorts after DNA damage. Another consequence of genotoxic stress is that centrosomes undergo duplication outside the normal cell cycle stage, meaning that centrosome amplification is commonly seen after DNA damage. We discuss several potential mechanisms for how centrosome numbers become dysregulated after DNA damage and explore the links between the DDR and the PLK1- and separase-dependent mechanisms that drive centriole separation and reduplication. We also describe how centrosome components, such as centrin2, are directly involved in responding to DNA damage. This review outlines current questions on the involvement of centrosomes in the DDR.     

Does the motor branch of the long head of the triceps brachii arise from the radial nerve?

Anatomy textbooks say that the motor branch of the long head of the triceps brachii (LHT) arises from the radial nerve. Some clinical observations of traumatic injuries of the axillary nerve with associated paralysis of the LHT have suggested that the motor branch of the LHT may arise from the axillary nerve. This anatomic study was performed, using both cadaver anatomical dissections and a surgical study, to determine the exact origin of the motor branch of the LHT. From the adult cadaver specimens (group I), 20 posterior cords were dissected from 10 subjects (eight embalmed, two fresh) using 3.5× magnification. The axillary nerve was followed from its onset to the posteromedial part of the surgical neck of the humerus and the radial nerve. We looked for the origin of the proximal branch of the LHT by a meticulous double anterior and posterior dissection. From the surgical group (group II), 15 posterior cords were dissected from 15 patients suffering from a C5-C6 injured paralysis, without paralysis of the LHT. During the surgical procedure, we looked for the origins of the motor branch of the LHT with a nerve stimulator. In group I, the motor branch of the LHT arose in 13 cases from the axillary nerve near its origin, in five cases from the terminal division of the posterior cord itself, and in two cases from the posterior cord 10 mm before its terminal division into the radial and axillary nerves. In no case did we find the motor branch of the LHT arising from the radial nerve. In eight cases, we found some accessory branches that arose near the principal branch. In group II, the motor branch of the LHT arose in 11 cases from the axillary nerve near its origin and in four cases from the terminal division of the posterior cord itself. The motor branch of the LHT never originated from the radial nerve. In four cases, we found some accessory branches that arose near the principal branch of the LHT. These results reveal that the motor branch of the LHT seems to originate most often from the axillary nerve. This contribution could be relevant for surgical treatment of traumatic nerve injuries.     

Can the Nerve Growth Factor promote the reinnervation of the transplanted heart?

The activity of the heart is widely regulated by the autonomous nervous system. This important mechanism of control may be impaired in chronic diseases such as heart failure or lost in those patients who undergo heart transplantation, owing to the surgical interruption of cardiac nerves in the transplanted heart. It has been demonstrated that spontaneous reinnervation can occur in transplanted hearts and is associated with an improvement in cardiac function. However, this process may require many years and the restoration of a proper cardiac innervation and functioning during exercise is never complete. In this perspective, the Nerve Growth Factor (NGF) and other neurotrophic hormones might ameliorate cardiac innervation in the transplanted heart and should be tried in animal models. Endothelial cells engineered with a viral vector to overexpress the NGF might be engrafted in the heart and integrate into cardiac small vessels, thus providing a source of neurotrophic factors which might promote and direct regrowth and axonal sprouting of cardiac nerves.     

The decidua—the maternal bed embracing the embryo—maintains the pregnancy

The decidua has been known as maternal uterine tissue, which plays essential roles in protecting the embryo from being attacked by maternal immune cells and provides nutritional support for the developing embryo prior to placenta formation. However, there are questions that still remain to be answered: (1) How does the decidua supply nutrition and provide a physical scaffold for the growing embryo, before placental vascular connection is established? (2) How is the balance between preventing an anti-embryo immune response and protecting both embryo and mother from infections established? To understand basic personas in decidual tissues, we review the structure of the decidua composed of terminally differentiated uterine stromal cells, blood vessels, and a number of repertoire of uterine local immune cells, including the well-known uterine natural killer (uNK) cells and recently discovered innate lymphoid cells (ILCs). Decidual macrophages and uterine dendritic cells (DCs) are supposed to modulate adaptive immunity via balancing cytokines and promoting generation of regulatory T (T_reg) cells. During decidualization, vascular and tissue remodeling in the uterus provide nutritional and physical support for the developing embryo. Secretion of various cytokines and chemokines from both the embryo and the decidual cells activates multiple signaling network between the mother and the embryo upon implantation. Defects in the decidual development during early pregnancy result in loss of pregnancy or complications in later gestational stage.     

Does the development of the perigeniculate nucleus support the notion of a hierarchical progression within the visual pathway?

The development of the visual pathway has been extensively studied. However, despite of the importance of the perigeniculate nucleus within this pathway, there is a lack of information concerning its development. The present study examined the dendritic development of perigeniculate nucleus cells using single cell injections in 400-500 microm thick fixed brain slices from kittens of different ages between postnatal day 0 and postnatal day 125. A total of 189 perigeniculate nucleus cells were reconstructed from serial sections for qualitative and quantitative analysis. Cells during the first month were characterized by an abundance of branch points and appendages. There was a significant (P>0.05), albeit variable, increase in the number of branch points and appendages up to about postnatal day 12 after which the numbers were rapidly reduced over the next two weeks. Similarly, appendage numbers significantly increased over the first two weeks until postnatal day 17 and then fell to near adult levels by postnatal day 34. The majority of branch points and appendages occur within 100-200 microm of the soma (10-30% of the dendritic diameter). The data indicate that perigeniculate nucleus dendritic maturation lags shortly behind that of the retina but may precede that of its dorsal thalamic target, the lateral geniculate nucleus. Thus, it may be that the earlier maturation of the perigeniculate nucleus and its inhibitory input is a necessary requirement for the proper development of retinogeniculate and corticothalamic topographic maps within the dorsal lateral geniculate nucleus and perigeniculate nucleus.     

What are the factors responsible for the deviation in stepping on the spot?

Without vision, keeping a straight-ahead direction while stepping on the spot is almost impossible, everybody deviates more or less. Several explanations for this, such as laterality, vestibulo-spinal influence, dopamine system, have been proposed. The aims of the experiment presented here were (1) to quantify the lateral deviation when stepping using a modified Fukuda test apparatus, and (2) to determine the factors potentially underlying such deviation. Twenty-five young adults, blindfolded, performed the experiment which consisted in stepping while holding a rotating vertical roll bar fixed on the wall. Four experimental conditions (i.e., normal, with an imposed pace, dual-task, or with the neck bent) were tested. All participants deviated towards one side or the other in all conditions. Adding an attentional load or imposing a particular pace did not change the amount of deviation. For three conditions (normal, with an imposed pace and dual-task), the deviation towards one side was not significantly larger than towards the other side at the group level. In the bent-neck condition, the deviation was significantly larger than in the other conditions. Furthermore, in this condition the deviation towards the left was significantly larger than the deviation towards the right at the group level. We discussed the results regarding the role of vestibular information and proprioceptive feedback from neck muscles in correcting a spontaneous deviation. Our results, however, go against the idea that sensorimotor lateral preferences are among the factors underlying such deviations, since we found no relationship between lateral preferences (hand, foot, and eye) and the side of deviation.