Neurosecretory endings in the rat neurohypophysis are en passant

A combination of Golgi, Phaseolus vulgaris leucoagglutinin, and transmission electron microscopic (EM) techniques was used to investigate the morphology of neurosecretory axons and their endings in the neurohypophysis of the rat. Light microscopy indicated that the neurosecretory processes are very tortuous, varicose, and branched, often running in close association with blood vessels. EM, as well as reconstruction from serial thin sections, demonstrated that the combination of synaptoid membrane specializations, dense core vesicles, and accumulations of microvesicles, thought to indicate areas of preferential hormone release, can occur anywhere that the axons contact the basal lamina (BL) lining the perivascular space. Usually, but not always, this was accompanied by some degree of axonal dilation. Individual neurosecretory axons frequently entwined around, or ran adjacent to, blood vessels, a short length of axon forming multiple "endings." Thin glial (pituicyte) processes were interposed between these endings. Axonal processes were also seen to end blindly as end-bulbs suspended in the perivascular space where they were often surrounded by pituicyte processes. The morphology observed suggests that reductions in the contact length of individual nerve terminals could be mediated through increased pituicyte coverage along BL. Conversely, a reduction of pituicyte coverage along the BL could lead to more areas of axonal contact with the BL inducing or allowing the formation of more endings, such as has been reported to occur during lactation or prolonged elevation of plasma testosterone levels.     

Implication of biofilm formation in the persistence of urinary tract infection caused by uropathogenic Escherichia coli

Escherichia coli is the most frequent microorganism involved in urinary tract infection (UTI). Acute UTI caused by uropathogenic E. coli (UPEC) can lead to recurrent infection, which can be defined as either re-infection or relapse. E. coli strains causing relapse (n = 27) and re-infection (n = 53) were analysed. In-vitro production of biofilm, yersiniabactin and aerobactin was significantly more frequent among strains causing relapse. Biofilm assays may be helpful in selecting patients who require a therapeutic approach to eradicate persistent biofilm-forming E. coli strains and prevent subsequent relapses.     

Dye-coupled magnocellular peptidergic neurons of the rat paraventricular nucleus show homotypic immunoreactivity

Magnocellular neurons in rat hypothalamic slices are known to exhibit dye coupling: the transfer of the fluorescent dye, Lucifer Yellow, from an intracellularly-injected neuron to one or more nearby neurons. The question of the hormonal identity of coupled cells and the possibility of dye coupling as an artefact led us to determine the immunoreactivity of dye-coupled magnocellular neurons in the paraventricular nucleus of the rat hypothalamus using antisera to oxytocin- and vasopressin-associated neurophysins. In 23 pairs, one triplet, and one quadruplet, immunoreactivity to one or the other antiserum was always exclusive, and dye coupling was always homotypic, that is, coupled neurons in each instance were reactive to the same antiserum. The quadruplet, triplet and 17 pairs were immunoreactive to vasopressin-associated neurophysin, and oxytoxin-associated neurophysin immunoreactivity was observed in the remaining pairs. Immunoreactivity to each antiserum was found for somasomatic and non somasomatic modes of coupling and for coupled neurons in the three magnocellular areas of the nucleus. A relationship between mode of coupling and hormone content was not detected. The data support the hypothesis that coupling is a real, functionally significant mechanism for coordinating neuronal activity in this nucleus, particularly under conditions of high hormone demand. They do not support the idea that coupling is artefact. The possibility of a relationship between hormone content and mode of coupling, and the projection pathway(s) of the coupled neurons of each type require further study.     

The Royal Army Dental Corps Museum archive ( circa 1917-1920)

This is the fourth in a series of historical articles, edited by David J. Smithson, which explores surviving clinical photographic archives from the 19th and 20th centuries.     

The mucopolysaccaridoses

The mucopolysaccaridoses are a collection of rare genetic conditions where there is a defect in lysosomal storage causing an accumulation of glycosaminoglycans. There are seven different forms of mucopolysaccaridosis (MPS), each with a different enzymatic mutation and thus each form has similar but separate clinical features. There are multiple effects of glycosaminoglycan deposition including musculoskeletal manifestations such as joint problems and growth arrests. Common treatments of the orthopaedic complications include hip arthroplasty, cervical spine surgery and epiphyseal stapling to correct genu valgum. Presently, the only curative treatment for MPS is haematopoietic stem cell transplantation. Enzyme replacement therapy is a future target for all forms of MPS and a range of therapies are currently in development.     

Are Quadrilateral Surface Buttress Plates Comparable to Traditional Forms of Transverse Acetabular Fracture Fixation?

Background

Several construct options exist for transverse acetabular fracture fixation. Accepted techniques use a combination of column plates and lag screws. Quadrilateral surface buttress plates have been introduced as potential fixation options, but as a result of their novelty, biomechanical data regarding their stabilizing effects are nonexistent. Therefore, we aimed to determine if this fixation method confers similar stability to traditional forms of fixation.

Questions/purposes

We biomechanically compared two acetabular fixation plates with quadrilateral surface buttressing with traditional forms of fixation using lag screws and column plates.

Methods

Thirty-five synthetic hemipelves with a transverse transtectal acetabular fracture were allocated to one of five groups: anterior column plate + posterior column lag screw, posterior column plate + anterior column lag screw, anterior and posterior column lag screws only, infrapectineal plate + anterior column plate, and suprapectineal plate alone. Specimens were loaded for 1500 cycles up to 2.5x body weight and stiffness was calculated. Thereafter, constructs were destructively loaded and failure loads were recorded.

Results

After 1500 cycles, final stiffness was not different with the numbers available between the infrapectineal (568 ± 43 N/mm) and suprapectineal groups (602 ± 87 N/mm, p = 0.988). Both quadrilateral plates were significantly stiffer than the posterior column buttress plate with supplemental lag screw fixation group (311 ± 99 N/mm, p < 0.006). No difference in stiffness was identified with the numbers available between the quadrilateral surface plating groups and the lag screw group (423 ± 219 N/mm, p > 0.223). The infrapectineal group failed at the highest loads (5.4 ± 0.6 kN) and this was significant relative to the suprapectineal (4.4 ± 0.3 kN; p = 0.023), lag screw (2.9 ± 0.8 kN; p < 0.001), and anterior buttress plate with posterior column lag screw (4.0 ± 0.6 kN; p = 0.001) groups.

Conclusions

Quadrilateral surface buttress plates spanning the posterior and anterior columns are biomechanically comparable and, in some cases, superior to traditional forms of fixation in this synthetic hemipelvis model.

Clinical Relevance

Quadrilateral surface buttress plates may present a viable alternative for the treatment of transtectal transverse acetabular fractures. Clinical studies are required to fully define the use of this new form of fixation for such fractures when accessed through the anterior intrapelvic approach.     

Asplenia in two father-son Pairs

We report on two father-son pairs with isolated nonsyndromal asplenia. This may represent autosomal dominant inheritance of a mutation in a gene involved with spleen development and determination of laterality. The incidence of hereditary isolated asplenia is unknown; therefore, screening for asplenia in first degree relatives of individuals with (poly)asplenia should be considered. © 1995 Wiley-Liss, Inc.