A thermodynamic model of bone remodelling: the influence of dynamic loading together with biochemical control.

Understanding of the bone remodelling process has considerably increased during the last 20 years. Since the ability to simulate (and predict) the effects of bone remodelling offers substantial insights, several models have been proposed to describe this phenomenon. The strength of the presented model is that it includes biochemical control factors (e.g., the necessity of cell-to-cell contact, which is mediated by the RANKL-RANK-OPG chain during osteoclastogenesis) and mechanical stimulation, the governing equations are derived from interaction kinetics (e.g., mass is preserved in running reactions), and the parameters are measurable. Behaviour of the model is in accordance with experimental and clinical observations, such as the role of dynamic loading, the inhibitory effect of dynamic loading on osteoclastogenesis, the observation that polykaryon osteoclasts are activated and formed by a direct cell-to-cell contact, and the correct concentrations of osteoblasts, osteoclasts, and osteocytes. The model does not yet describe the bone remodelling process in complete detail, but the implemented simplifications describe the key features and further details of control mechanisms may be added.

Aeromonas hydrophila colitis in a child.

A 5-year-old girl presented with chronic bloody diarrhea. Evaluation including sigmoidoscopy, rectal biopsy, and barium enema was consistent with the diagnosis of ulcerative colitis. Culture of the stool grew Aeromonas hydrophila. A. hydrophila colitis may be more common than presently realized.

Cerebral blastomycosis: an immunodiagnostic study.

Cerebral blastomycosis may simulate a brain tumor. Its diagnosis is sometimes very difficult. The morphologic identification of the fungus may be misleading because it shares some common features with many other dimorphic fungi. Culturing and conversion of the organism from mycelial phase to yeast phase are not always successful. Immunofluorescent staining of the biopsy tissue is useful in confirming the diagnosis. However, a combination of double immunodiffusion (DID) test and complement fixation (CF) test makes the diagnosis more accurate and reliable. The direct role of macrophages in defending the host against blastomycosis is illustrated by electron microscopy.

Comparison of a rapid micromedia method to cystine trypticase agar (CTA) and fluorescent methods for the identification of pathogenic Neisseria.

A four-hour micromedia method which detects enzymes formed by bacteria for the degradion of carbohydrates was compared to the utilization of carbohydrates was compared to the utilization of carbohydrates in cystine tyrpticase agar (CTA) for the identification of Neisseria gonorrhoeae and Neisseria meningitidis. This rapid micromedia method (RMM) correlated 100% with the utilization of carbohydrates in CTA. Identification of N. gonorrhoeae by RMM was compared to the identification achieved by a commercially available coagglutination method and a fluorescent antibody (FA) technique. Of 144 isolates identified as N. gonorrhoeae by RMM, 122 (84.7%) were identified by coagglutination and 141 (97.9%) were identified by FA as N. gonorrhoeae. Five (13%) of 40 isolates identified as N. meningitidis by RMM were identified as N. gonorrhoeae by coagglutination while eleven (28%) were identified as N. gonorrhoeae by the FA technique. One (14%) and four (57%) of seven isolates identified as Neisseria species were identified as N. gonorrhoeae by coagglutination and the FA technique respectively. The rapid micromedia method was found to be a quick, sensitive, specific and economic way of identifying N. gonorrhoeae and N. meningitidis.