OSTEOCLASTS: ORGANIZATION IN CHICK EMBRYO BONE

A multinucleated endosteum was observed in the long bones of chick embryos aged 14 to 17 days. The endosteum appears to be responsible for extensive bone resorption; the bulk of the diaphyseal bone is almost completely replaced during this particular 3-day interval. Eventually, the endosteum appears to be transformed into numerous individual osteoclasts. Both the endosteum and the osteoclasts are found almost entirely on the medial surfaces of the innermost bone spicules and they seem to destroy collagen by extracellular proteolysis.     

Seroprevalence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in Danish horses

Background

Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum are able to infect horses. However, the extend to which Danish horses are infected and seroconvert due to these two bacteria is unknown. The aim of the present study was to evaluate the seroprevalence of B. burgdorferi sensu lato and A. phagocytophilum in Danish horses.

Methods

A total of 390 blood samples collected from all major regions of Denmark and with a geographical distribution corresponding to the density of the Danish horse population were analyzed. All samples were examined for the presence of antibodies against B. burgdorferi sensu lato and A. phagocytophilum by the use of the SNAP^®4DX ^® ELISA test.

Results

Overall, 29.0% of the horses were seropositive for B. burgdorferi sensu lato whereas 22.3% were seropositive for A. phagocytophilum.

Conclusions

Antibodies against B burgdorferi sensu lato and A. phagocytophilum are commonly found among Danish horses thus showing that Danish horses are frequently infected by these organisms.     

Isolation, culture and ultrastructure of a xylem-limited bacterium associated with Sumatra disease of cloves

A xylem-limited bacterium (XLB) previously shown to be associated with Sumatra disease of clove trees was consistently isolated from diseased but not from healthy trees. Isolation of the XLB was most successful using freshly expressed bacterial ooze obtained from root and branch tissues with low to moderate levels of xylem vessel invasion in trees at early stages of disease. XLB were commonly isolated from trees with the rapid form of disease but infrequently from those with slow decline. Bacterial colonies grew slowly on nutrient agar, reaching a maximum diameter of 1 mm in 5-7 days at 28^oC. Cells of the bacterium were 0.5-0.6 μm in width and 1.0-1.5 μm in length and did not possess flagella. The bacterial envelope was strongly rippled and Gram negative.     

Association of a xylem-limited bacterium with Sumatra disease of cloves in Indonesia

Sumatra disease is highly destructive in most clove-growing areas of Sumatra and in western parts of Java. Symptoms of leaf-fall and twig die-back, starting in the upper branches, and often associated with wilting, lead to tree death in 6–18 months. Normally, only seedlings and young trees survive. Symptoms are usually more severe and disease spread is more rapid at higher elevations. Patterns of jump-spread suggest that the disease agent is carried via an airborne pathway, possibly by insect vectors. Small, Gram-negative, non-motile, rod-shaped bacteria are consistently associated with the disease. Initial attempts to culture the bacteria in vitro did not succeed. The bacteria are confined within xylem vessels and are found throughout diseased trees. Greyish-brown streaks are present in wood of heavily infected tissues which release a bacterial ooze from cut surfaces; in such tissues many of the vessels are occluded by bacteria embedded in a gelatinous matrix. At the time of first above-ground symptoms, bacteria are already well established in roots and the trunk base, from where they appear to spread upwards in newly formed wood into the crown of the tree. Symptoms are thought to result from root dysfunction and mechanical blockage of the vascular system. All known clove varieties appear equally susceptible.     

Sumatra disease in cloves induced by a xylem-limited bacterium following mechanical inoculation

Suspensions of a Gram negative, non motile nutritionally fastidious bacterium, cultured from clove trees affected by Sumatra disease and inoculated by needle puncture into the xylem of seedling cloves and young trees, caused the death of over 60% of the plants withing 2 year. Bacteria, confined to zylem vesssels, occurred throughout the vascular systems of dying plants and were also still active in some of the plants which survived for 3 years after inoculation. Bactria resembling those used as inoculum were readily reisolated form dying plants but not from any water-treated controls. Symptoms in experimental plants and the appearance and distribution of vessels occluded by bacteria were indistinguishable from those resulting from natural infection. All clove types tested were susceptible, including progeny from trees which had survived past disease attack. Result suggest the importance of using vigorously growing plants and providing protection against full sunlight during incubation for the successful establishment of beacterial infection in juvenile clove plants follwing mechanical inoculation.     

Skin Fold Advancement Flaps for Closing Large Sternal and Inguinal Wounds in Cats and Dogs

Skin fold advancement flaps can be created from the elbow and flank folds to close large wounds in the pectoral and inguinal regions of cats and dogs, respectively. The attachments of the laterally facing (outer) and medially facing (inner) layers of the skin fold to the adjacent limb are divided to produce a U-shaped pedicle graft attached to the trunk. This mobilizes skin that can be advanced over large wounds involving the ventral chest or abdomen, or both. The use of skin fold advancement flaps enables direct closure of large skin defects without undue tension and without compromising the mobility of the adjacent limb.     

Towards Ethically Improved Animal Experimentation in the Study of Animal Reproduction

The ethics of animal-based research is a continuing area of debate, but ethical research protocols do not prevent scientific progress. In this paper, we argue that our current knowledge of the factors that affect reproductive processes provides researchers with a solid foundation upon which they can conduct more ethical research and simultaneously produce data of higher quality. We support this argument by showing how a deep understanding of the genetics, nutrition and temperament of our experimental animals can improve compliance with two of the '3 Rs', reduction and refinement, simply by offering better control over the variance in our experimental model. The outcome is a better experimental design, on both ethical and scientific grounds.