The early host and material response of hydroxyapatite/β-tricalciumphosphate porous ceramics after implantation into the femur of rats

The early responses of host and hydroxyapatite/-tricalciumphosphate (HA-TCP) porous ceramic implants were studied using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) at 3, 7, 14, 21, and 28 days after implantation into the femur of rats. Micropores (<5 m) and macropores of the implant surface provided effective structures for anchoring of various tissue components. Mineralization started directly on the implant surface and was observed in macropores and micropores, suggesting bone-bonding by epitaxis. Bone-bonding was observed with and without an amorphous intervening interface layer. The composition of this layer and the mechanisms guiding its production are not yet fully understood. Extracellular matrix filled up the clefts between HA-TCP crystal grain clusters. These processes contributed to the mechanical stabilization of the interface. Slight changes of implant grain surface morphology were observed which were explained by leaching of impurities, such as TCP and/or by dissolution acting on single grains. Diameters of pores and HA-TCP grains did not change in a period up to 28 days, which seems to be related to the relatively short periods of insertion and the material properties. Leaching and degradation were observed and loose particles of implant origin were phagocytosed by macrophages and multinuclear giant cells which dominated at non-bonding interfaces.     

L-thiocitrulline. A stereospecific, heme-binding inhibitor of nitric-oxide synthases

Nitric-oxide synthase (NOS) catalyzes the oxidation of L-arginine to citrulline and nitric oxide (NO). The enzyme is inhibited by a variety of N omega-monosubstituted L-arginine analogs, and some of these compounds are useful in reversing pathologies associated with the overproduction of NO (e.g. the hypotension of septic shock). We report here that L-thiocitrulline (gamma-thioureido-L-norvaline) is a potent, stereospecific inhibitor of the constitutive brain and endothelial isoforms of NOS as well as the isoform induced in vascular smooth muscle cells by lipopolysaccharide and interferon-gamma. Steady state kinetic studies show L-thiocitrulline inhibition is competitive with L-arginine (Ki approximately 4-20% of KArgm), indicating that initial binding is as a substrate/product analog. In contrast to L-arginine and N omega-methyl-L-arginine, the prototypic NOS inhibitor, L-thiocitrulline binding elicits a "Type II" difference spectrum, indicating a high spin to low spin transition of the iron in the heme cofactor. This finding suggests that L-thiocitrulline is contributing the sixth ligand to heme iron, probably through the thioureido sulfur. Such interaction with heme iron neither stimulates nor inhibits the direct flavin-mediated cytochrome c reduction activity of the enzyme, but it does inhibit heme-dependent superoxide formation. In vivo, L-thiocitrulline is a potent pressor agent in both normal and endotoxemic rats, the latter finding suggesting utility in treating the hypotension of septic shock.     

Viral interleukin 10 (IL-10), the human herpes virus 4 cellular IL-10 homologue, induces local anergy to allogeneic and syngeneic tumors

After the cloning of murine cytokine synthesis inhibitory factor, it was recognized that a homologous open reading frame was encoded within the Epstein-Barr virus (human herpes virus 4). This viral protein has now been termed viral interleukin 10 (vIL-10) to reflect its protein sequence homology to "cellular" IL-10 (cIL-10, either murine or human IL-10). It is now widely accepted that vIL-10 shares many functions with cIL-10, principally, the ability to enhance survival of newly infected B cells and to diminish the production of IFN-gamma and IL-2 during ongoing immune reactions. The immunomodulatory effect of locally secreted vIL-10 and murine IL-10 (mIL-10) was examined in tumor models using CL8-1 (a BL6 melanoma cell line transfected with the H-2Kb class I gene) in syngeneic animals. Although parental BL6 tumor cells grow in immunocompetent syngeneic hosts, CL8-1 are rejected. To achieve local secretion of vIL-10, we generated vIL-10 retroviral vectors. While nontransduced CL8-1 cells (1 x 10(4)) failed to grow when injected intradermally in C57BL/6 mice, CL8-1 cells (1 x 10(4)) transduced with vIL-10 formed palpable tumors and eventually killed 80% of injected animals. Suppression of tumor rejection was also noted when CL8-1 tumors with or without vIL-10 transfection were admixed with syngeneic vIL-10-transfected fibroblasts and inoculated. Since the in vitro proliferation of the tumor was not altered after transduction with the vIL-10 gene and injection of vIL-10-transduced CL8-1 does not affect the rejection of nontransduced CL8-1 inoculated at a distant site, local vIL-10 secretion appears to suppress the process of immune rejection of the target cells in a dose-dependent manner. Similar results were observed for the H-2b MCA105 sarcoma tumor model in allogeneic BALB/c mice (H-2d). Although all animals that received nontransfected MCA105 rapidly rejected these tumors, MCA105 sarcomas transfected with vIL-10 remained palpable for up to 37 d. The local immunosuppressive effect of gene-delivered vIL-10 could be neutralized by anti-human IL-10 monoclonal antibody or could be reversed by the systemic administration of IL-2 or IL-12. In marked contrast, mIL-10 transfection of CL8-1 significantly suppressed tumor growth and frequently led to the rejection of tumor. Similar results were obtained for the murine tumor cell lines MCA102.(ABSTRACT TRUNCATED AT 400 WORDS)     

Evolution of the cranial computed tomography scan in child abuse

Computed tomography (CT) scans obtained at the time of clinical presentation have occasionally been reported to be normal in children with history and findings of significant abusive head injury. We have retrospectively observed abnormalities in "normal" scans of some similar children. We have also seen abnormalities develop on serial scanning. To determine how frequently these situations occur, we reviewed charts of 34 children with a final diagnosis of child abuse who also had cranial CT scans performed. Their CT scans were retrospectively reviewed by a pediatric radiologist. Eleven (11/34) CT scans had initially been interpreted as normal. Four (4/11) of these had been reinterpreted during the hospitalization as abnormal, affecting medical (1) and legal (3) outcome. Repeat scanning in three of the remaining seven resulted in surgical drainage of a subdural effusion (1) and affected legal outcome (2). Four of the seven initial scans felt normal throughout the hospitalizations were judged abnormal on retrospective review. This evaluation was confirmed in the two rescanned. Initial CT interpretation most often failed to appreciate changes in parenchymal density and small amounts of falcine or cortical subdural blood. Subsequent scans also showed evolving effusions and infarcts. Changes were noted in 1 1/2 to 5 days. The CT scan frequently shows subtle changes in the immediate posttrauma period. If the child does not recover promptly, subsequent scans frequently result in significant changes in clinical and legal management.     

Localization of atrial natriuretic peptide receptors in the rat tongue and hard palate

The effect of a naturally occurring plant phenolic constituent (the acylphloroglucinol derivative, jensenone, derived from Eucalyptus jensenii) on the food intake of two folivorous marsupials, the common ringtail (Pseudocheirus peregrinus) and the common brushtail possum (Trichosurus vulpecula) was studied. When fed diets containing varying concentrations of jensenone, both species regulated their intake of jensenone so as not to exceed a ceiling intake. This ceiling was about twice as high for common ringtails as for common brushtails from northern Australia. Southern populations of common ringtails showed greatly reduced capacities to tolerate jensenone. When common brushtails were injected (0.5 mg.kg-0.75 body mass) with ondansetron (a selective antagonist of serotonin 5HT3 receptors), they ate significantly more jensenone than animals injected with physiological saline. The same pattern was observed when common ringtails were fed diets containing both jensenone and ondansetron (0.0035 mg.g-1 wet mass of diet). Ondansetron injection had no effect on food intake when the food did not contain jensenone while the addition of higher doses of ondansetron to diets of common ringtails very slightly reduced food intakes of a non-jensenone diet. When common brushtails were given 50 mg of jensenone by gastric lavage, their average subsequent intake of dietary jensenone matched the difference between the daily threshold and the dose given, although the response of individuals was highly variable. Lavage with water alone had no effect on subsequent jensenone intake compared with the pre-dose period. We interpret these results as evidence that the antifeedant effects of jensenone and related compounds are partly mediated by serotonin action on 5HT3 receptors most likely via "nausea" to condition a food aversion.     

Conformations and folding of lysozyme ions in vacuo

Proton transfer reactivity of isolated charge states of the protein hen egg-white lysozyme shows that multiple distinct conformations of this protein are stable in the gas phase. The reactivities of the 9+ and 10+ charge state ions, formed by electrospray ionization of "native" (disulfide-intact) and "denatured" (disulfide-reduced) solutions, are consistent with values calculated for ions in their crystal structure and fully denatured conformations, respectively. Charge states below 8+ of both forms, formed by proton stripping, have similar or indistinguishable reactivities, indicating that the disulfide-reduced ions fold in the gas phase to a more compact conformation.     

Sleep-induced breathing instability. University of Wisconsin-Madison Sleep and respiration Research Group

We present a view of the neuromechanical regulation of breathing and causes of breathing instability during sleep. First, we would expect transient increases in upper airway resistance to be a major cause of transient hypopnea. This occurs in sleep because a hypotonic upper airway is more susceptible to narrowing and because the immediate excitatory increase in respiratory motor output in response to increased loads is absent in non-REM sleep. Secondly, sleep predisposes to an increased occurrence of ventilatory "overshoots", in part because abruptly changing sleep states cause transient changes in upper airway resistance and in the gain of the respiratory controller. Following these ventilatory overshoots, breathing stability will be maintained if excitatory short-term potentiation is the prevailing influence. On the other hand, apnea and hypopnea will occur if inhibitory mechanisms dominate following the ventilatory overshoot. These inhibitory mechanisms include: a) hypocapnia-if transient, will inhibit carotid chemoreceptors and cause hypopnea, but if prolonged will inhibit medullary chemoreceptors and cause apnea; b) a persistent inhibitory effect from lung stretch; c) baroreceptor stimulation, from a transient rise in systemic blood pressure immediately following termination of apnea or hypopnea may partially suppress the accompanying hyperpnea; d) depression of central respiratory motor output via prolonged brain hypoxia. Once apneas are initiated, reinitiation of inspiration is delayed even though excitatory stimuli have risen well above their apneic thresholds, and these prolonged apneas are commonly accompanied by tonic EMG activation of expiratory muscles of the chest wall and upper airway.     

Urinary proteomic analysis of chronic allograft nephropathy

The pathogenesis of progressive renal allograft injury, which is termed chronic allograft nephropathy (CAN), remains obscure and is currently defined by histology. Prospective protocol-biopsy trials have demonstrated that clinical and standard laboratory tests are insufficiently sensitive indicators of the development and progression of CAN. The study aim was to determine if CAN could be characterized by urinary proteomic data and identify the proteins associated with disease. The urinary proteome of 75 renal transplant recipients and 20 healthy volunteers was analyzed using surface enhanced laser desorption and ionization MS. Patients could be classified into subgroups with normal histology and Banff CAN grades 2-3 with a sensitivity of 86% and a specificity of 92% by applying the classification algorithm Adaboost to urinary proteomic data. Several urinary proteins associated with advanced CAN were identified including α1-microglobulin, β2-microglobulin, prealbumin, and endorepellin, the antiangiogenic C-terminal fragment of perlecan. Increased urinary endorepellin was confirmed by ELISA and increased tissue expression of the endorepellin/perlecan ratio by immunofluoresence analysis of renal biopsies. In conclusion, analysis of urinary proteomic data has further characterized the more severe CAN grades and identified urinary endorepellin, as a potential biomarker of advanced CAN.