Bone marrow stromal cell bioactivation and detoxification of the benzene metabolite hydroquinone: comparison of macrophages and fibroblastoid cells

Bone marrow stroma consists predominately of two cell types, macrophages and fibroblastoid stromal cells, which regulate the growth and differentiation of myelopoietic cells via the production of growth factors. We have previously shown that macrophages are more sensitive than fibroblastoid stromal cells (LTF cells) to the toxic effects of the benzene metabolite hydroquinone. In this study, the role of selective bioactivation and/or deactivation in the macrophage-selective effects of hydroquinone was examined. LTF and macrophage cultures were incubated with 10 microM [14C]hydroquinone to examine differential bioactivation. After 24 hr, the amount of 14C covalently bound to acid-insoluble macromolecules was determined. Macrophages had 16-fold higher levels of macromolecule-associated 14C than did LTF cells. Additional experiments revealed that hydroquinone bioactivation to covalent-binding species was hydrogen peroxide dependent in macrophage homogenates. Covalent binding in companion LTF homogenates was minimal, even in the presence of excess hydrogen peroxide. These data suggest that a peroxidative event was responsible for bioactivation in macrophages and, in agreement with this, macrophages contained detectable peroxidase activity whereas LTF cells did not. Bioactivation of [14C]hydroquinone to protein-binding species by peroxidase was confirmed utilizing purified human myeloperoxidase in the presence of hydrogen peroxide and ovalbumin as a protein source. High performance liquid chromatographic analysis of incubations containing purified myeloperoxidase, hydroquinone, and hydrogen peroxide showed that greater than 90% of hydroquinone was removed and could be detected stoichometrically as 1,4-benzoquinone. 1,4-Benzoquinone was confirmed as a reactive metabolite formed from hydroquinone in macrophage incubations using excess GSH and trapping the reactive quinone as its GSH conjugate, which was measured by high performance liquid chromatography with electrochemical detection. The activity of DT-diaphorase, a quinone reductase that has been invoked as a protective mechanism in quinone-induced toxicity, was 4-fold higher in LTF cells than macrophages. These data suggest that the macrophage-selective toxicity of hydroquinone results from higher levels of peroxidase-mediated bioactivation and/or lower levels of DT-diaphorase-mediated detoxification.     

Immune reactions in human filariasis.

Sera from cases of elephantiasis due to Wuchereria bancrofti infection promoted an intense adhesion of peripheral blood leukocytes to W. bancrofti microfilariae in vitro. A similar adhesion was also seen using sera from some normal persons living for several years in areas where filariasis is endemic. No such adhesion was evident with sera from microfilaria carriers or from normal subjects from nonendemic areas. The adhesion was complement independent and was associated with the immunoglobulin G fraction of serum. 51Cr release studies suggested the occurrence of cell-mediated cytotoxicity to W. bancrofti microfilariae in the presence of elephantiasis serum. Microfilariae of Litomosoides carinii could be isolated free of blood cells, from the blood of infected rats. In the presence of serum, or its immunoglobulin G fraction, from patients with elephantiasis, L. carinii microfilariae adhered to human peripheral blood leukocytes or rat spleen cells.     

Calcium pyrophosphate dihydrate deposition disease causing thoracic cord compression: case report

OBJECTIVE AND IMPORTANCE: Calcium pyrophosphate dihydrate (CPPD) deposition disease is being increasingly recognized. Spinal involvement in CPPD deposition disease is rare. When involved, the cervical and lumbar regions are commonly affected. We report a rare case of CPPD deposition disease that caused thoracic cord compression. CLINICAL PRESENTATION: A 45-year-old woman presented with clinical features suggestive of thoracic cord compression. Radiographic findings were consistent with calcification of the ligamenta flava in the lower thoracic levels causing cord compression. Calcification of the ligamentum flavum is commonly attributed to CPPD deposition disease. Evaluation for conditions that might be associated with CPPD deposition disease proved to be negative. INTERVENTION: Laminectomy with removal of the calcified ligamenta flava was performed. Histopathological examination of the excised ligaments revealed evidence of CPPD crystals. Postoperatively, the patient's spasticity decreased and sensations improved, with no significant improvement in motor power. CONCLUSION: Calcification of the ligamenta flava due to CPPD deposition disease is a rare cause of thoracic cord compression. CPPD deposition disease should be entertained in the differential diagnosis of thoracic cord compression.     

Do Trauma Patients Aged 55 and Older Benefit from Air Medical Transport?

Introduction: A recent analysis of the National Sample Project demonstrated that the mortality benefits of air medical transport do not extend to patients age 55 or older. The purpose of the current investigation was to evaluate mortality benefits of air transport in adult trauma patients ≥ 55 years of age. Methods: A retrospective analysis of all adult patients greater than age 55 years directly transported from a trauma scene to a Level I or II facility was conducted. The primary outcome variable was in-hospital mortality. Using the imputed dataset we then performed multivariable logistic regression with mortality as the dependent variable to determine if mode of transport had a significant impact on mortality for patients older than 55 years of age. Results: There were 7,739 (90.9%) patients transported by ground and 682 (9.1%) transported by air in our dataset. There were 3,556 between the ages of 55 to 69 years and an additional 4865 over the age of 69 years. In the multivariable model of all patients ≥ 55, air transport was associated with lower mortality (adjusted odds ratio [aOR] = 0.60; 95% confidence interval [CI] = 0.39--0.91; p = 0.017) when compared to those transported by ground. Conclusion: Our study was able to demonstrate a survival benefit for the cohort of patients age greater than 55 years of age.     

Exosomes expressing the self‐antigens myosin and vimentin play an important role in syngeneic cardiac transplant rejection induced by antibodies to cardiac myosin

Long‐term success of heart transplantation is hindered by humoral and cell‐mediated immune responses. We studied preexisting antibodies to cardiac self‐antigens, myosin and vimentin, and exosomes induced by antibodies to self‐antigens in eliciting immune responses to cardiac grafts. After syngeneic heterotopic murine heart transplantation, rabbit anti‐myosin or normal rabbit immunoglobulin was administered at day 0 or 7. Sera were collected after heartbeat cessation, cellular infiltration was analyzed, and exosomes were isolated from sera. Histopathologic examination of the controls' transplanted hearts demonstrated normal architecture, and their sera demonstrated neither antibodies to self‐antigens nor exosomes expressing self‐antigens. Administration of antibodies to cardiac myosin immediately posttransplantation (day 0) but not on day 7 triggered graft failure on day 7, and histopathologic examination revealed marked cellular infiltration with neutrophils and lymphocytes. Histopathologic examination of rejected hearts also demonstrated myocyte damage as sera had increased antibodies to myosin and vimentin and development of exosomes expressing self‐antigens. Administration of exosomes isolated from failed grafts containing self‐antigens induced graft dysfunction; exosomes isolated from stable mice did not induce graft failure. Antibodies to self‐antigens can induce exosomes containing self‐antigens, initiating an immune response and causing graft failure after cardiac transplantation.     

Glucose and fat metabolism in adipose tissue of acetyl-CoA carboxylase 2 knockout mice

Acc2-/- mutant mice, when fed a high-fat/high-carbohydrate (HF/HC) diet, were protected against diet-induced obesity and diabetes. To investigate the role of acetyl-CoA carboxylase 2 (ACC2) in the regulation of energy metabolism in adipose tissues, we studied fatty acid and glucose oxidation in primary cultures of adipocytes isolated from wild-type and Acc2-/- mutant mice fed either normal chow or a HF/HC diet. When fed normal chow, oxidation of [14C]palmitate in adipocytes of Acc2-/- mutant mice was approximately 80% higher than in adipocytes of WT mice, and it remained significantly higher in the presence of insulin. Interestingly, in addition to increased fatty acid oxidation, we also observed increased glucose oxidation in adipocytes of Acc2-/- mutant mice compared with that of WT mice. When fed a HF/HC diet for 4-5 months, adipocytes of Acc2-/- mutant mice maintained a 25% higher palmitate oxidation and a 2-fold higher glucose oxidation than WT mice. The mRNA level of glucose transporter 4 (GLUT4) decreased several fold in the adipose tissue of WT mice fed a HF/HC diet; however, in the adipose tissue of Acc2-/- mutant mice, it was 7-fold higher. Moreover, lipolysis activity was higher in adipocytes of Acc2-/- mutant mice compared with that in WT mice. These findings suggest that continuous fatty acid oxidation in the adipocytes of Acc2-/- mutant mice, combined with a higher level of glucose oxidation and a higher rate of lipolysis, are major factors leading to efficient maintenance of insulin sensitivity and leaner Acc2-/- mutant mice.     

Timely triggering of homeostatic mechanisms involved in the regulation of T-cell levels in SIVsm-infected sooty mangabeys

Sooty mangabeys, the natural host of simian immunodeficiency virus (SIVsm), generally avoid progressive depletion of CD4+ T cells and opportunistic infections associated with infection of humans (HIV) and macaques (SIVmac). The means by which the SIVsm-infected mangabeys maintain CD4+ T-cell levels despite high rates of viral replication is unknown. One cytokine that has a key role in the regulation of T-cell levels is interleukin-7 (IL-7). Here, the longitudinal assessment of 6 SIVsm-infected mangabeys identified an early increase in plasma IL-7 levels at weeks 1 to 5 after infection. This IL-7 increase correlated with an early decline in CD4+ T-cell levels (decline of 492-1171 cells/microL) accompanying acute viremia. Elevated IL-7 levels were followed by increased T-cell proliferation (Ki67) and maintenance of lower but stable (more than 500 cells/microL) CD4+ T-cell levels in each mangabey through 37 weeks of infection. These data contrast with our earlier studies in SIVmac-infected macaques, in which the IL-7 increase was delayed until 20 to 40 weeks after infection, just before the onset of simian AIDS. Taken together, these data suggest that timely triggering of IL-7 is important for stabilizing healthy T-cell levels in mangabeys and that timely administration of exogenous IL-7 may show benefit during pathogenic SIVmac and HIV infection.     

Growing skull fracture: two rare causes

Introduction

Growing skull fractures are rare complications of head injury in young children. Till date, growing skull fractures due to an underlying arrested hydrocephalus or subdural hygroma have not been reported. We are reporting two such rare cases.

Discussion

A 12-year-old male who was a known case of arrested hydrocephalus sustained a mild head injury and was found to have a linear fracture. One month after the initial injury, a soft swelling was noted in the parietal region. Investigations revealed the dilated ventricular system communicating through a growing skull fracture with a subgaleal CSF collection. The patient underwent a ventriculoperitoneal shunt using a high-pressure shunt system. The patient died suddenly 48 h after the surgery. An 8-month-old female child sustained a mild head injury with a linear fracture in the parieto-occipital region. Two months later, the child presented with seizures and a soft, fluctuant swelling in the parieto-occipital region. Imaging revealed a frontoparietal subdural hygroma with mass effect that was communicating through a growing skull fracture with a subgaleal CSF collection. The patient underwent a subduroperitoneal shunt. The shunt tube was removed 3 months later as it protruded through the abdominal wound. Follow-up imaging studies revealed complete resolution of the subdural hygroma with healing of the growing skull fracture.

Conclusions

Growing skull fractures can occur as complications of mild head injury sustained in the setting of either arrested hydrocephalus or subdural hygroma. Hence, close follow-up of patients with skull fracture and arrested hydrocephalus/subdural hygroma is necessary for early diagnosis of growing skull fractures.     

Accelerating bone defects healing in calvarial defect model using 3D cultured bone marrow‐derived mesenchymal stem cells on demineralized bone particle scaffold

Bone defects are usually difficult to be regenerated due to pathological states or the size of the injury. Researchers are focusing on tissue engineering approaches in order to drive the regenerative events, using stem cells to regenerate bone. The purpose of this study is to evaluate the osteogenic differentiation of bone marrow‐derived mesenchymal stem cells (BMSCs) on biologically derived Gallus gallus domesticus‐derived demineralized bone particle (GDD) sponge. The sponges were prepared by freeze‐drying method using 1, 2, and 3 wt% GDD and cross‐linked with glutaraldehyde. The GDD sponge was characterized using scanning electron microscopy, compressive strength, porosity, and Fourier transform infrared. The potential bioactivity of the sponge was evaluated by osteogenic differentiation of BMSCs using 3(4, dimethylthiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide assay and quantifying alkaline phosphatase (ALP) activity. in vivo experiments were evaluated through a micro‐computerized tomography (μ ‐CT) and histological assays. The analysis confirmed that an increase in the concentration of the GDD in the sponge leads to a higher bone formation and deposition in rat calvarial defects. Histological assay results were in line with μ ‐CT. The results reported in this study demonstrated the potential application of GDD sponges as osteoinductor in bone tissue engineering in pathological or nonunion bone defects.