Cellular basis of the immunohematologic defects observed in short-term semiallogeneic B6C3F1 -- C3H chimeras: evidence for host-versus-graft reaction initiated by radioresistant T cells

Lethally irradiated C3Hf mice reconstituted with a relatively low dose (2 × 10⁶) of B6C3F₁ bone marrow cells (B6C3F₁ → C3Hf chimeras) frequently manifest immunohematologic deficiencies during the first month following injection of bone marrow cells. They show slow recovery of antibody-forming potential to sheep red blood cells (SRBC) as compared to that observed in syngeneic (C3Hf → C3Hf or B6C3F₁ → B6C3F₁) chimeras. They also show a deficiency of B-cell activity as assessed by antibody response to SRBC following further reconstitution with B6C3F₁-derived thymus cells 1 week after injection of bone marrow cells. A significant fraction of B6C3F₁ → C3Hf chimeras was shown to manifest a sudden loss of cellularity of spleens during the second week following injection of bone marrow cells even though cellularity was restored to the normal level within 1 week. The splenic mononuclear cells recovered from such chimeras almost invariably showed strong cytotoxicity against target cells expressing donor-type specific H-2 antigens (H-2^b) when assessed by ⁵¹Cr-release assay in vitro. The effector cells responsible for the observed anti-donor specific cytotoxicity were shown to be residual host-derived T cells. These results indicate strongly that residual host T cells could develop anti-donor specific cytotoxicity even after exposure to a supralethal dose (1050 R) of radiation and that the immunohematologic disturbances observed in short-term F₁ to parent bone marrow chimeras (B6C3F₁ → C3Hf) were due to host-versus-graft reaction (HVGR) initiated by residual host T cells. The implication of these findings on the radiobiological nature of the residual T cells and the persistence of potentially anti-donor reactive T-cell clones in long-surviving allogeneic bone marrow chimeras was discussed.     

Caffeine biosynthesis in Camellia sinensis

The metabolism of adenine and guanine, relating to the biosynthesis of caffeine, in excised shoot tips of tea was studied with micromolar amounts of adenine-[8-¹⁴C] or guanine-[8-¹⁴C]. Among the presumed precursors of caffeine biosynthesis, adenine was the most effective, whereas guanine was the least effective. After administration of a ‘pulse’ of adenine-[8-¹⁴C], almost all of the adenine-[¹⁴C] supplied disappeared by 30 hr, and ¹⁴C-labelled caffeine and RNA purine nucleotide (AMP and GMP) synthesis increased throughout the experimental period, whereas the radioactivities of free purine nucleotides, 7-methylxanthine and theobromine increased during the first 10 hr incubation period, followed by a steady decrease. By contrast, more than 45% of the guanine-[8-¹⁴C] supplied remained unchanged even after a 120 hr period. The main products of guanine-[8-¹⁴C] metabolism in tea shoot tips were guanine nucleotides, theobromine, caffeine and the GMP of RNA. The results support the hypothesis that the purine nucleotides are synthesized from adenine and guanine via the pathway of purine salvage. Adenylate is readily converted into other purine nucleotides, whereas the conversion rate of guanylate into other purine nucleotides is very low.The results also support the view that 7-methylxanthine and theobromine are precursors of caffeine. For the origin of the purine ring in caffeine, purine nucleotides in the nucleotide pool rather than in nucleic acids are suggested.     

A new amine,stizolamine, from Stizolobium hassjoo

A new pyrazine derivative, stizolamine (1-methyl-3-guanidino-6-hydroxymethylpyrazin-2-one), has been isolated from seeds of Stizolobium hassjoo. This amine, which has a blue fluorescence, gives guanidine, N-methyl-alanine, oxalic acid, alanine and glycine on treatment with 6 N HCl. The permanganate oxidation product of stizolamine is 4-amino-6-methylcarbamoyl-1,3,5-triazine-2-carboxylic acid.     

Synthesis of methyl α- and β-maltotriosides and aryl β-maltotriosides

Reaction of β-maltotriose hendecaacetate with phosphorus pentachloride gave 2′,2″,3,3′,3″,4″,6,6′,6″,-nona-O-acetyl-(2)-O-trichloroacetyl-β-maltotriosyl chloride (2) which was isomerized into the corresponding α anomer (8). Selective ammonolysis of 2 and 8 afforded the 2-hydroxy derivatives 3 and 9, respectively; 3 was isomerized into the α anomer 9. Methanolysis of 2 and 3 in the presence of pyridine and silver nitrate and subsequent deacetylation gave methyl α-maltotrioside. Likewise, methanolysis and O-deacetylation of 9 gave methyl β-maltotrioside which was identical with the compound prepared by the Koenigs—Knorr reaction of 2,2′,2″,3,3′,3″,4″,6,6′,6″-deca-O-acetyl-α-maltotriosyl bromide (12) with methanol followed by O-deacetylation. Several substituted phenyl β-glycosides of maltotriose were also obtained by condensation of phenols with 12 in an alkaline medium. Alkaline degradation of the o-chlorophenyl β-glycoside decaacetate readily gave a high yield of 1,6-anhydro-β-maltotriose.     

The effect of alpha2-macroglobulin from bovine serum on bovine alpha-chymotrypsin.

Bovine alpha2-globulin contains a protein which increases the activity of bovine alpha-chymotrypsin against synthetic substrates. The active protein fraction migrates slowly on polyacrylamide gel electrophoresis, so it was named slow alpha2-globulin (Salpha2). The fraction was isolated from bovine serum and purified. Its sedimentation constant S20 was 18.5 S. It was thus identified with the alpha2-macroglobulin (alpha2M). By kinetic studies, the dissociation constant of the alpha-chymotrypsin-alpha2 M complex was calculated to be of the order of 10(-7) l/mol. The purified alpha2 M was shown to bind alpha-chymotrypsin at a definite rate. If the binding ratio was assumed to be 1:2, the molecular weight was calculated to be about 8 X 10(5).     

Effect of anti-beta2-microglobulin on antigen and allogeneic lymphocyte-induced proliferation of human lymphocytes.

The effect of anti-beta2-microglobulin (beta2m) on the mixed lymphocyte reaction (MLR), and an antigen-induced proliferative response was studied. Anti-beta2m IgG and Fab' fragments completely inhibited the MLR. Preincubation of stimulator or responder cells with anti-beta2m suggested that the major effect of anti-beta2m may be on the responder cell population. A clear-cut effect on responder cells was demonstrated by showing that anti-beta2m completely inhibited a MLR in which the stimulator population was a beta2m negative lymphoblastoid cell line. Anti-beta2m also inhibited PPD-induced proliferation of sensitized lymphocytes. The kinetics of this inhibition indicated that anti-beta2m added within the first 18 hr of stimulation was effective in inhibiting the proliferative response. These data are discussed in light of the hypothesis that beta2m may be a subunit of an antigen receptor on T cells.     

Synthesis of 6-Sulfur Analogues of Oxanosine and Closely Related Derivatives Thereof

Abstract

Novel β-D-ribofuranosides having a 5-substituted imidazo [4,5-d] [1,3]thiazine ring, including the S⁶-congener 3 of oxanosine 2, were synthesized for screening their anticancer and antiviral activities.     

Production of Antibacterial Compounds Analogous to Chloramphenicol by a n-Paraffin-grown Bacterium

Corynebacterium sp. KY 4339, when grown on n-paraffin (a mixture of C–12 to C–14 fractions) as the sole carbon source, produced three kinds of antibacterial compounds which were tentatively named Corynecins. These compounds were isolated by the extraction from the culture broth with ethyl acetate and by the chromatographies on silicic acid and alumina columns. Each component demonstrated some similarity to chloramphenicol on thin-layer chromatogram. Although their biological activities were not so remarkably as that of chloramphenicol, the patterns of antibacterial spectra against gram-positive and gram-negative bacteria resembled to it.

For the production of corynecins, n-paraffin was a preferable carbon source. By controlling the pH of the medium in the neutral range and keeping the aeration at a high level during the fermentation, approximately 3 g of corynecins per liter of the medium were produced after 72-hr incubation.     

Mouse genetics identifies unique and overlapping functions of fibroblast growth factor receptors in keratinocytes

Fibroblast growth factors (FGFs) are key regulators of tissue development, homeostasis and repair, and abnormal FGF signalling is associated with various human diseases. In human and murine epidermis, FGF receptor 3 (FGFR3) activation causes benign skin tumours, but the consequences of FGFR3 deficiency in this tissue have not been determined. Here, we show that FGFR3 in keratinocytes is dispensable for mouse skin development, homeostasis and wound repair. However, the defect in the epidermal barrier and the resulting inflammatory skin disease that develops in mice lacking FGFR1 and FGFR2 in keratinocytes were further aggravated upon additional loss of FGFR3. This caused fibroblast activation and fibrosis in the FGFR1/FGFR2 double‐knockout mice and even more in mice lacking all three FGFRs, revealing functional redundancy of FGFR3 with FGFR1 and FGFR2 for maintaining the epidermal barrier. Taken together, our study demonstrates that FGFR1, FGFR2 and FGFR3 act together to maintain epidermal integrity and cutaneous homeostasis, with FGFR2 being the dominant receptor.