Evaluation of bone height and bone density after tooth extraction: an experimental study in minipigs.

OBJECTIVE: The objective of this study was to radiographically quantify bone density and bone height preservation in tooth extraction alveolus filled with xenograft. STUDY DESIGN: The maxillary and mandibular fourth deciduous molars and fourth premolars of 6 minipigs were removed. Randomly, in 3 animals the right side was used as the test side and in the other 3 animals the left side was the test side. Intraoral radiographs were performed to compare the condition at the initial time and 3 months later. Measurements of bone height and bone density were performed using KS300 (Zeiss) software. RESULTS: After 3 months, there was a statistically significant smaller bone height loss for the test group. The test group presented a statistically greater bone density immediately after tooth extraction. However, after 3 months there was no statistically significant difference between the groups. CONCLUSIONS: The results suggest that treatment of postextraction alveolus with xenograft can preserve bone height initially but differences in bone density compared to when no xenograft is used are not sustained.     

The infeasibility of using ten-ring irradiated grafts for tracheal allotransplantation even with omentopexy

In our previous study, we demonstrated that high-dose ⁶⁰Co irradiation was able to prevent rejection of canine tracheal allografts. To determine the maximum possible length of these grafts, in the present study we attempted to transplant five-ring and ten-ring tracheal allografts in two groups of five dogs each. Either five or ten rings were excised from donor tracheas and irradiated with 100,000 cGy of ⁶⁰Co. The irradiated tracheal grafts were transplanted to replace either five- or ten-ring sections of the mediastinal tracheas removed from the recipient dogs. The grafts were covered with omental pedicles and no immunosuppressants were used. Graft incorporation was achieved in four of the five dogs in the five-ring group, and three of these dogs survived for more than 700 days. However, four of the five animals in the ten-ring group died from tracheostenosis accompanied by ischemia within 3 weeks. These findings demonstrate the impossibility of performing ten-ring tracheal allotransplantation using irradiated grafts, even with omentopexy.     

The effect of a mixture of tegafur with uracil (UFT) on hepatocarcinogenesis in rats induced by 3'-methyl-4-dimethylaminoazobenzene. I. The influence on production of alpha-fetoprotein

We studied the effect of UFT (a mixture of Tegafur and uracil at a ratio of 1:4) on hepatocarcinogenesis and alpha-fetoprotein (AFP) production induced by 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) in rats. By feeding rats with 3'-MeDAB diet, serum AFP started to appear from week 2-3 and increased until week 5-7, then declined until week 10-11. This phenomenon of a transient appearance of serum AFP is called "primary reaction". After week 11 hepatoma started to develop accompanied with an enormous elevation of serum AFP level until animals die, generally before week 25. Male Donryu strain rats fed a diet containing 0.06% 3'-MeDAB for 10 weeks, and then fed the normal diet. UFT was given by a stomach tube once a day for five days a week. Blood was collected from the tail vein every other week and serum AFP was measured by Rocket electrophoresis technique. When the administration of UFT (10 mg or 20 mg/kg/day) was started simultaneously with feeding 3'-MeDAB diet, the primary reaction was somewhat suppressed, and after week 11 development of hepatoma and elevation of AFP were markedly inhibited. The administration of UFT of a high dose (40 mg/kg/day) caused the death of animals in 7 weeks probably because of its toxicity. When the administration of UFT (10 mg or 20 mg/kg/day) was started after finish of feeding 3'-MeDAB diet for 10 weeks, the drug was not effective. These results show that if the administration of UFT was commenced at the same time with feeding 3'-MeDAB diet, the hepatocarcinogenesis and AFP production are strongly inhibited.     

Fine structure of the mouse portal vein in relation to its peristaltic movement

The hepatic portal vein has been known to make a spontaneous peristaltic movement in some mammals, including the mouse and rat. To investigate the fine structure of the portal vein in relation to its physiological characteristics, we observed the mouse portal vein by using various histological techniques including conventional light microscopy, videomicroscopy, transmission and scanning electron microscopy, and real-time confocal laser scanning microscopy. The mouse hepatic portal vein was provided with a spiral fold which was produced by the inner layer, i.e. the endothelium and smooth muscles of the wall protruding into the lumen. Longitudinal smooth muscle cells spanned the interval of the fold, like a spirally arranged palisade around the vessel wall. The longitudinal muscle fibers ended at the spiral fold, being partly connected with a network of irregularly shaped smooth muscle cells. This network, hitherto unknown, was recognized to be restricted to the fold in distribution and characterized by numerous gap junctions connecting the muscle cells. Real-time confocal laser scanning microscopy using a Ca2+ sensitive fluorescent dye revealed that a transient and periodic increase in Ca2+ concentration occurred in the longitudinal smooth muscle cells and was transmitted spirally from the intestinal to the hepatic side. These findings indicate that, during the peristaltic movement, the contraction of smooth muscle cells is transmitted along the longitudinal smooth muscles of the portal vein wall toward the liver, presumably controlled by the network of the irregularly-shaped smooth muscle cells in the fold of the portal vein. Light microscopic observation in some specimens indicated an occurrence of cardiac muscle cells outside the smooth muscle layer. Restricted to the site of the porta hepatis in distribution, their involvement in the peristaltic contraction of the portal vein seemed unlikely.     

Bcl11b is required for differentiation and survival of alphabeta T lymphocytes

The gene Bcl11b, which encodes zinc finger proteins, and its paralog, Bcl11a, are associated with immune-system malignancies. We have generated Bcl11b-deficient mice that show a block at the CD4-CD8- double-negative stage of thymocyte development without any impairment in cells of B- or gammadelta T cell lineages. The Bcl11b-/- thymocytes showed unsuccessful recombination of V(beta) to D(beta) and lacked the pre-T cell receptor (TCR) complex on the cell surface, owing to the absence of Tcrb mRNA expression. In addition, we saw profound apoptosis in the thymus of neonatal Bcl11b-/- mice. These results suggest that Bcl11b is a key regulator of both differentiation and survival during thymocyte development.     

Molecular assembly of RNA polymerase II from the fission yeast Schizosaccharomyces pombe: subunit–subunit contact network involving Rpb5

Background: Eukaryotic RNA polymerase II is composed of more than 10 polypeptide chains. The minimum and essential subunits for RNA synthesis have not yet been identified. Toward this ultimate goal, we analysed the topological arrangement of the putative subunits. Here we report a subunit–subunit contact network involving subunit 5 of the fission yeast Schizosaccharomyces pombe RNA polymerase II.
Results: The rpb5 ⁺ gene encoding subunit 5 of RNA polymerase II was cloned from the fission yeast Schizosaccharomyces pombe . The polypeptide predicted from DNA sequence of the rpb5 ⁺ gene consists of  210 amino acids with a calculated molecular weight of 23 914. The homology of the amino acid sequence is 55% and 43% with Saccharomyces cerevisiae RPB5 and human hRPB25, respectively. Far-Western blot analysis of S. pombe RNA polymerase II using ³²P-labelled recombinant Rpb5 fused to glutathione S-transferase (GST) as a probe, indicated that Rpb5 binds strongly to membrane-immobilized Rpb1, Rpb2 and Rpb3 and weakly to Rpb5 and a 15-kDa subunit (Rpb8 or Rpb11). In agreement with this result, the ³²P-labelled Rpb3 probe showed a strong binding signal against Rpb5 in addition to Rpb1 and Rpb2. The existence of Rpb5–Rpb3 contact was supported by detection of complexes formed between these two proteins synthesized in vitro using protein-immobilized beads.
Conclusion: Rpb3 and Rpb5, the putative subunits of RNA polymerase II, associate each other to form binary complexes. These two subunits also bind to the two large subunits, Rpb1 and Rpb2, independently.     

Fate redirection of hippocampal astrocytes toward neuronal lineage by aggregate culture

Mammalian cells that have been committed to a certain cell lineage cannot be directed to other lineages. However, some astrocytes in the mammalian brains have been reported to represent plasticity to redirect to other cell lineages. We found that mouse hippocampal astrocytes cultured in aggregate forms of "astrosphere", redirected to MAP2-positive immature neurons. In astrospheres, basic HLH factors positively regulating neuronal differentiation were up-regulated and Id3 inhibiting basic HLH factors was down-regulated. Ectopic Id3 induction repressed redirection of astrocytes to a neuronal lineage, suggesting that astrosphere formation induced plasticity of astrocytes by changing the gene expression patterns.     

Interaction of Arc with CaM kinase II and stimulation of neurite extension by Arc in neuroblastoma cells expressing CaM kinase II

We investigated the relationship between Arc (activity-regulated cytoskeleton-associated protein) and Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase II). Arc and CaM kinase II were concentrated in the postsynaptic density. These proteins were accumulated after electroconvulsive treatment. Arc increased about 2.5-fold within 30 min and was maintained at this level for 8h after the stimulation. CaM kinase II also increased within 30 min and remained at this level for at least 24h. The interaction of Arc with CaM kinase II was demonstrated using GST-Arc fusion protein, and confirmed in neuroblastoma cells by immunoprecipitation. We examined the function of Arc by introducing Arc cDNA into neuroblastoma cells expressing CaM kinase II. The cells expressing both Arc and CaM kinase II had longer neurites than those expressing CaM kinase II alone. Arc itself did not promote neurite outgrowth. The growth of neurites by Arc was completely blocked by treatment with KN62, an inhibitor of CaM kinases. These results indicated that Arc potentiated the action of CaM kinase II for neurite extension.     

Chorioamnionitis caused by Serratia marcescens in a non-immunocompromised host

A 26 year old pregnant woman with antithrombin III deficiency developed recurrent septicaemia with Serratia marcescens. In spite of the administration of antibiotics, high grade fever persisted. She subsequently manifested lower abdominal pain, and spontaneous abortion occurred. After the abortion, she became completely afebrile. The amnion was turbid, and microscopic examination of the placenta showed haemorrhage and massive infiltration of neutrophils, suggestive of infectious chorioamnionitis. Pulsed field gel electrophoresis showed that isolates from the blood, urine, and vaginal discharge were genetically identical. Intravenous pyelography revealed that she had a bilateral completed double ureter. It was thought that a urinary tract anomaly caused infection with S marcescens, and the pathogen spread to the chorioamnion via the bloodstream. This is the first report of chorioamnionitis caused by S marcescens in a non-immunocompromised host. In addition, these findings indicate that the chorioamnion can serve as a site for persistent infection in normal pregnancies.