Chemical and biological properties of a peptidoglycan isolated from Treponema pallidum kazan.

A peptidoglycan layer of Treponema pallidum kazan was isolated by solubilization of whole cells with 1% warm sodium dodecyl sulfate and subsequent digestion of an insoluble residue with proteases. Electron microscopy revealed that the peptidoglycan was isolated as a single-layered sacculus of less than 5 nm in thickness, freed from axial filaments and an envelope sheath. An isolated peptidoglycan fraction was mainly composed of glucosamine, muramic acid, alanine, glutamic acid, ornithine, and glycine in molar ratios of 0.65:0.68:1.63:1.00:0.75:1.03. Amino (N)- and carboxyl (C)-terminal amino acid analyses suggested the involvement of at least a part of the glycine residue in cross-linking between the amino group of ornithine residue at one strand of the stem peptide subunit and the carboxyl group of alanine of the neighboring strand. The treponemal peptidoglycan lacked the immunoadjuvant activity both to stimulate antibody production and to induce delayed-type hypersensitivity against ovalbumin, as well as the properties necessary to stimulate guinea pig and mouse splenocytes and guinea pigs peritoneal macrophages, unlike the cell walls or peptidoglycans (group A type of Schleifer and Kandler's classification, Bacteriol. Rev. 36:407-477, 1972) isolated from many bacterial species parasitic to the mammal. However, the peptidoglycan activated the human complement system through the alternative pathway, as well as the classical one, and caused a liberation of 5-hydroxytryptamine in rabbit blood platelets in a similar manner to the cell wall peptidoglycans of both group A and B types.     

Determination of the depth of 50% of maximum ionization, I50, for electron beams by the divided difference method

A new characterization of depth-ionization parameters for electron beams is empirically deduced from our data analysis based on the divided difference method (the DD method), which employs the numerical differential of an ionization curve. The important feature of the present method is that it does not necessarily require normalized percent depth-ionization (NPDI) data. The depth of 50% of maximum ionization, I50, which is an important parameter for electron beam dosimetry, can be deduced from the analysis of an unnormalized (or partial) depth-ionization (UDI) curve obtained over a short interval of depth. The values of I50 determined by the DD method are in agreement to within 0.1 mm for energies of 4, 6, and 9 MeV, compared with the ones determined by the TG-51 protocol method (or the conventional method), and the difference was 0.9 mm for 12 and 15 MeV. The dose at the reference depth, dref, calculated from I50 by the DD method, is found to be in agreement with TG-51 to within 0.1%. The field size dependence of the DD method using UDI data was studied for three field sizes: 6 x 6, 10 x 10, and 20 x 20 cm2. For all energies, the discrepancies of I50 as determined by both methods were 0.9 mm on average for the 6 x 6 cm2 fields and 0.6 mm for the other two field sizes. This dependence was remarkable for 6 x 6 cm2 fields for 12 and 15 MeV, and the discrepancies shown by the DD method were 1.2 mm for 12 MeV and 1.8 mm for 15 MeV, respectively. Since the reference field size in clinical dosimetry is usually 10 x 10 cm2, this dependence will not affect clinical dosimetry. The DD method could be an alternative option for checking beam quality in dose calibration.     

The role of γδ T cells in priming macrophages to produce tumor necrosis factor-α

The secretion of tumor necrosis factor (TNF)-α from macrophages is regulated by both priming and triggering signals. We found that macrophages from mice lacking γδ T cells [T cell receptor (TCR) δ^?/- mice], which lack the gene encoding the δ chain, produced only small amounts of TNF-α in response to lipopolysaccharide (LPS) and showed a reduced level of expression of CD14. Pre-incubation of macrophages from TCR δ-/- mice with γδ T cells from their TCR δ^+/- littermates restored their capacity to produce TNF-α in response to LPS. The priming activity of γδ T cells was in part inhibited by neutralizing anti-interferon (IFN)-γ monoclonal antibodies. Collectively, these results suggest that γδ T cells play a role in priming macrophages to a steady state of activation via IFN-γ secretion, which allows them to produce TNF-α when exposed to LPS.     

Osteosarcoma occurring in osteogenesis imperfecta

We describe a case history of a 24-year-old male with osteogenesis imperfecta (OI) who developed osteosarcoma of the left thigh. High-dose ifosfamide therapy caused marked tumor regression of multiple lung metastases. Immunohistochemically, the tumor cells were diffusely positive for the p53 protein. Mutation of the p53 gene was not detected by direct genomic sequencing of exons 4–8. The radiographic characteristics, including irregularly distributed osteolytic lesions and cortical discontinuity, should not be confused with hyperplastic callus formation, a benign process. A biopsy is critical to establish the differential diagnosis between osteosarcoma and common hyperplastic callus formation in OI; however, it must be applied with great care.     

Determination of diquat in biological materials by electron spin resonance spectroscopy

Summary An electron spin resonance (ESR) method already in use for the quantitative analysis of paraquat was applied to the analysis of diquat in blood, serum, urine, tissue homogenates and several drinks without purification of the samples. The diquat radical produced with ascorbic acid at alkaline pH was much more stable than that produced with the commonly used sodium dithionite. Radical decay in solutions covered with n-hexane was less than 5% after 60 min over a wide range of ascorbic acid concentrations. In 0.2N NaOH solution 85% of the radicals was present even after 24h. The limit of detection was 0.3 g/ml and the required amount of sample was 0.1 ml. When both diquat and paraquat were present in a sample the diquat was first extracted with 1-butanol prior to the ESR measurement, because both species were converted to the radicals.     

Is the site of action of ketamine anesthesia the N-methyl-D-aspartate receptor?

Synaptic mechanisms underlying ketamine anesthesia were studied using in vitro preparations of the lamprey CNS. Although lampreys are one of the most primitive vertebrates, the synaptic physiology and pharmacology are similar to those in the higher vertebrates. Axonal conduction, transmitter release from the presynaptic terminal, postsynaptic response to the putative neurotransmitters, and resting and activated membrane properties were studied in the absence and the presence of various concentrations of ketamine. Ketamine markedly reduced N-methyl-D-aspartate (NMDA)-activated responses, such as depolarizations to bath-applied NMDA and bursting rhythm during "fictive locomotion." The 50% block of the responses took place in the presence of 10-20 microM ketamine, whereas those induced by kainate and quisqualate (the other two subclasses of L-glutamate/L-aspartate agonists) were spared at concentrations higher than 600-800 microM. None of the other neuronal events tested were suppressed in the presence of still higher concentrations of ketamine. The results support the hypothesis that ketamine might exert its anesthetic effect by a pharmacologically specific interaction with the NMDA receptor.     

Reduction of cell proliferative activities of gastric stump adenomatous hyperplasias after bile reflux diversion in rats

Previously we reported the majority of lesions induced by bilereflux, in the absence of chemical carcinogens, in the rat remnantstomach to consist primarily of gastric type and secondarilyof intestinal type cells, and that they are reversible afterdiversion of bile reflux. The present study was designed toevaluate changes in proliferative activities in cells of eachtype under these conditions. The frequency of adenomatous hyperplasia(AH) induced in the gastric stump mucosa by duodenal contentreflux after Billroth II partial gastrectomy (BII) increaseduntil the 54th week of the experiment. Roux-en-Y (RY) surgicalprocedure which prevents duodenal reflux performed at the 24thor 36th week after BII led to a decrease in AH. Cell contentof the lesions was analyzed using routine H&E staining,immunohistochemical staining for pepsinogen isoenzyme 1 andhistochemical procedures for mucins (paradoxical concanavalinA, galactose oxidase Schiff and sialidase galactose oxidaseSchiff reactions) and proliferation in each compartment evaluatedby an immunohistochemical method using bromodeoxyuridine (BrdU)and a monoclonal antibody against BrdU. At the 54th week thenumber of BrdU-labeled cells per normal pyloric column was significantly(P < 0.05) increased to 10.63/pit after the BII operation,while it diminished to 5.23/pit after RY diversion, this beingthe same level as with the RY procedure alone. AH maintaineda high rate of BrdU incorporation at 12.7% after BII operation,which was also significantly reduced (P < 0.01) to 7.0% bythe RY surgery. The intestinal type cell showed highest (22.2%),the surface mucous type cell showed the next (16.5%) and thepyloric gland type cell showed lowest (5.2%) BrdU labeling indicesafter BII operation. All the cell types in AH showed similarproportional decreases in BrdU incorporation after RY diversion.Thus surgical intervention reverses the cell proliferation causedby bile reflux in the gastric stump.     

Assessment of high-energy phosphorus compounds in the rat kidney by in situ31P nuclear magnetic resonance spectroscopy: effect of ischemia and furosemide

Summary ³¹P nuclear magnetic resonance (NMR) spectroscopy of the in situ rat kidney was performed by a surface coil method, and the effects of ischemia and furosemide infusion were assessed.³¹P NMR spectra of the kidney subjected to 30 min of ischemia returned completely to the pre-ischemic level after 60 min of reperfusion. But the³¹P NMR spectra after 60 min of ischemia did not recover, even after 120 min of reperfusion. Levels of -ATP and inorganic phosphate (Pi) decreased and the chemical shift of Pi increased after intravenous infusion of furosemide. This increase in chemical shift might signal an alkalotic change in intracellular pH. Furosemide infusion prior to ischemia is thought to protect the kidney from injury induced by 60 min of warm ischemia. The chemical shift of Pi returned to the pre-ischemic level earlier than -ATP and Pi. In conclusion, according to the findings of³¹P NMR spectroscopy, furosemide infusion prior to ischemia may be effective in protecting the kidney against ischemic injury. But the change in Pi peak and the causes of the dissociation of Pi and -ATP should be examined further.     

Natural killer activity and serum immunosuppressive acidic protein levels in esophageal and gastric cancers

The natural killer (NK) activity of peripheral blood mononuclear cells and serum immunosuppressive acidic protein (IAP) levels were examined in patients with esophageal or gastric cancer, before and after surgery. Patients with stage IV esophageal or stage IV gastric cancer had significantly lower NK activity (39.5±14.8% and 37±11.6%, respectively), and also higher serum IAP levels (778±264 g/mL and 633±156 g/mL, respectively), than the corresponding control values (50±5.6% and 375±26 g/mL, respectively). Patients with esophageal or gastric cancer who underwent curative resection had high NK activity (54.8±11.6% and 54.8±8.0%, respectively), and low IAP levels (471±116 g/mL and 490±42 g/mL, respectively), compared with those who underwent non-curative resection. Patients who underwent non-curative resection had lower NK activity and higher serum IAP levels than those who underwent curative resection, even 1 month after surgery. Mononuclear cells in the regional lymph nodes and tumor specimens showed significantly lower NK activity than those in the peripheral blood and spleen. Thus, NK activity and the IAP level reflected the immunocompetence, clinical course, and surgical curability of those patients. NK cells appeared not to have any significant antitumor activity in the regional lymph nodes or in the tumor itself, although they were still active in the peripheral blood.