Intrinsic regulation of hemangioma involution by platelet-derived growth factor.

Infantile hemangioma is a vascular tumor that exhibits a unique natural cycle of rapid growth followed by involution. Previously, we have shown that hemangiomas arise from CD133+ stem cells that differentiate into endothelial cells when implanted in immunodeficient mice. The same clonally expanded stem cells also produced adipocytes, thus recapitulating the involuting phase of hemangioma. In the present study, we have elucidated the intrinsic mechanisms of adipocyte differentiation using hemangioma-derived stem cells (hemSCs). We found that platelet-derived growth factor (PDGF) is elevated during the proliferating phase and may inhibit adipocyte differentiation. hemSCs expressed high levels of PDGF-B and showed sustained tyrosine phosphorylation of PDGF receptors under basal (unstimulated) conditions. Inhibition of PDGF receptor signaling caused enhanced adipogenesis in hemSCs. Furthermore, exposure of hemSCs to exogenous PDGF-BB reduced the fat content and the expression of adipocyte-specific transcription factors. We also show that these autogenous inhibitory effects are mediated by PDGF receptor-ß signaling. In summary, this study identifies PDGF signaling as an intrinsic negative regulator of hemangioma involution and highlights the therapeutic potential of disrupting PDGF signaling for the treatment of hemangiomas.

Catastrophic microangiopathy induced by high-titre factor VIII inhibitors after liver transplantation for haemophilia A with cirrhosis.

Liver transplantation may induce immune tolerance to factor VIII inhibitors but de novo development of inhibitors after transplantation may cause intractable haemorrhage. We report a patient with mild haemophilia A and high-titre FVIII inhibitors who received an orthotopic liver transplantation for complications of hepatitis C virus cirrhosis. Recombinant activated FVII was used in addition to routine haemostatic agents. Conventional immunosuppression was supplemented with antithymocyte globulin and cyclophosphamide. FVIII inhibitors disappeared from the circulation with liver transplantation but they were found to have bound to the graft endothelium, which became activated and induced catastrophic microangiopathy. A subsequent anamnestic response resulted in FVIII inhibitor titres of 1000 Bethesda Units. Uncontrollable haemorrhage persisted until the recipient's death. In patients with high-titre FVIII inhibitors resilient desensitization is required before liver transplantation.

Pulmonary sclerosing hemangioma with lymph node metastases.

Pulmonary sclerosing hemangioma is an unusual benign tumour of uncertain histogenesis. In the past 50 years, hundreds of cases have been described. A case of sclerosing hemangioma with some unusual features, including a false-positive fine needle aspiration biopsy and histological evidence of lymph node metastases, is described.

Handling individual mammalian embryos using microfluidics.

We have designed, built, and tested microfluidic systems capable of transporting individual, preimplantation mouse embryos (100-microm to 150-microm diameter) through a network of channels. Typical channels are 160 to 200 microm deep, 250 to 400 microm wide at the top, and narrower at the bottom (0 to 250 microm wide) due to the fabrication process. In these channels, a pressure gradient of 1 Pa/mm causes the medium to flow on the order of 10(-10) m3/s (100 nl/s), with an average speed of 1 to 2 mm/s. Under these flow conditions the embryos roll along the bottoms of the channels, traveling at 1/2 the speed of the fluid. By manipulating the pressure at the wells connected to the ends of the channels, the embryos can be transported to (and retained at) specific locations including culture compartments and retrieval wells.

Effect of respiratory syncytial virus on subsequent allergic sensitization to ovalbumin in guinea-pigs.

Children with acute respiratory syncytial virus (RSV) bronchiolitis often develop recurrent wheezing, asthma and allergic sensitization, but the role of RSV in the pathogenesis of these sequelae is unclear. This study examined whether RSV infection potentiates subsequent allergic sensitization, airway hyperresponsiveness (AHR) and airway inflammation induced by repeated exposures to aerosolized ovalbumin (OA) in guinea-pigs. Guinea-pigs received either RSV or sham inoculum, followed by exposures to OA- or saline-containing aerosols to form the following groups: 1) noninfected, nonsensitized controls (sham/saline group); 2) RSV-infected, nonsensitized animals (RSV/ saline group); 3) noninfected, OA-sensitized animals (sham/OA group); 4) RSV infection and first OA exposure on the same day (RSV/OA group), and 5) RSV infection six days prior to first OA exposure (RSV6/OA group). Three days after the final aerosol exposure, circulating OA-specific immunoglobulin (Ig)G1 antibody titres and AHR to inhalation acetylcholine challenge were measured and morphometry performed to evaluate allergic inflammation of the airways. OA-exposed animals developed OA-specific IgG1 antibodies, AHR and airway eosinophilia (sham/OA, RSV/OA and RSV6/OA groups. RSV infection alone induced significant AHR and airway eosinophilia (RSV/saline group). RSV infection, and concomitant exposure to OA (RSV/OA group) enhanced OA-specific IgG1 antibodies, but not airway eosinophilia or AHR. Such increases were not observed in the RSV6/OA group. In conclusion, respiratory syncytial virus potentiates the production of ovalbumin-specific immunoglobulin G1 antibodies in guinea-pigs, but circulating titres of these antibodies do not reflect the extent of airway hyperresponsiveness or airway inflammation. In addition, respiratory syncytial virus infection alone can produce slight increases in airway hyperresponsiveness that are associated with increased numbers of eosinophils in the airways.

Usefulness of bronchoalveolar lavage for diagnosis of acute and persistent respiratory syncytial virus lung infections in guinea pigs.

To investigate whether bronchoalveolar lavage (BAL) fluid specimens can be used to diagnose acute and persistent respiratory syncytial virus (RSV) lung infections in guinea pigs, we tested BAL fluid and lung tissue specimens for evidence of viral infection, and compared BAL cytology between infected and uninfected animals. RSV-inoculated guinea pigs were studied during acute bronchiolitis (days 3 and 7 postinoculation), convalescence (Day 14 postinoculation), and persistent infection (Days 28 and 60 postinoculation), and were compared to the sham-infected control animals. BAL and lung tissue specimens were cultured for virus and tested by immunocytochemistry for viral protein. A reverse transcription-polymerase chain reaction (RT-PCR) method was used to test for viral nucleic acid. Total and differential BAL cell counts were compared between RSV-inoculated and control animals on each study day. In BAL specimens, replicating RSV was isolated by culture in one out of four of the animals on Day 3 postinoculation; immunocytochemistry for RSV antigens was positive in all virus-exposed animals from Days 3-14 postinoculation, and viral nucleic acid was detected by RT-PCR in one-fourth of the animals on Day 3 postinoculation. In contrast, replicating virus, viral antigens, and viral nucleic acid were documented in lung tissues obtained from the same RSV-infected animals on all study days. BAL specimens of RSV-inoculated animals contained more eosinophils on all study days (two-tailed P value < 0.01) compared to the controls. The results of this animal study demonstrate that BAL fluid is not useful for diagnosis of persistent RSV infection. However, BAL fluid may be helpful for the documentation of acute RSV lung infection when immunocytochemistry may provide a more accurate test for virus detection than RT-PCR or viral culture.

Artemisinin, Related Sesquiterpenes, and Essential Oil in Artemisia annua During a Vegetation Period in Vietnam.

The active principle of ARTEMISIA ANNUA L., artemisinin, is currently being developed to a registered antimalarial drug. For production purposes, plants with a high artemisinin content are required. We followed the development of the artemisinin content and of the biosynthetically related sesquiterpenes artemisinic acid, arteannuin B, and artemisitene in A. ANNUA plants, during a vegetation period in Vietnam, where this species is indigenous. In addition, the essential oil content and composition were studied. Samples of leaves, buds, flowers, or post-bloom flowers and fruits were taken at different stages: vegetative (5, 6, and 8 months old), at mass formation of buds (9 months), at full bloom (10 months), and post-bloom (10S months). The highest artemisinin content (0.86% dry wt) was present in the leaves of 5 months-old plants. At this stage also the highest leaf yield was found. Subsequently, the artemisinin content gradually dropped. At the age of 5 months the highest artemisinic acid and arteannuin B contents, 0.16 and 0.08% dry wt, respectively, were found as well. Artemisitene was present at all stages of development, ranging from 0.002 to 0.09% dry wt. With 1.9% v/w, the essential oil content was maximal just before flowering and was composed of 55% monoterpenes and 45% sesquiterpenes. At all other stages (0.4 - 1.0% v/w oil) this ratio was ca. 30%/70%. The main components of the oil were camphor and germacrene-D.