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PubMed1988

Sequences of the VH and VL regions of murine monoclonal antibodies against 3-fucosyllactosamine.

Many mAb that bind the carbohydrate antigenic determinant 3-fucosyl-lactosamine (3-FL), Gal beta 1-4[Fuc alpha-3]GlcNAc-R have been raised in BALB/c mice, and we are studying the structure and regulation of these antibodies. In this report, we present the first information about their amino acid sequences and the Ig gene segments used to encode them. V regions of the H and L chains of three anti-3-FL antibodies, PMN6, PMN29, and PM81, were sequenced by a combination of mRNA and amino acid sequencing. The L chain sequences of PMN6 and PM81 antibodies indicate that their VK and JK regions are encoded by VK24B and JK1 germ-line genes, respectively. The nucleotide and amino acid sequences of the H chains suggest that the three anti-3-FL antibodies are encoded by the VH441 gene segment of the X24 VH family, and this conclusion was supported by Southern filter hybridization with VH441 and JH3-JH4 probes. PMN29 has at least 11 amino acid substitutions, which is an unusually large amount of somatic mutation for an IgM antibody. Previous analyses of BALB/c genomic libraries with VHX24 and VH441 probes make it unlikely that this VH family contains additional germ-line genes, but this possibility cannot be excluded. All three antibodies use the DQ52 and JH4 gene segments. The single VH and VL gene segments used to encode the anti-3-FL antibodies is in contrast to the multiple VH and VL segments used by antibodies against other carbohydrate Ag such as alpha 1-6 dextran and group A streptococcal carbohydrate. VH441 also encodes the VH regions of antibodies against galactan and levan (beta 2-6 fructosan). The similarities among VH segments of antibodies against 3-FL, levan, and galactan, and the striking differences in their CDR3 sequences, suggest that CDR3 plays an important role in the formation of the Ag binding site. The use of a single VH segment from the smallest VH gene family by antibodies against at least three different carbohydrate determinants is noteworthy. It raises the possibility that the amino acid sequence encoded by VH441 has some general structural features that make it particularly well adapted for binding to carbohydrate sequences.

Amino Acid Sequence↗
PubMedDate not supplied

Bone marrow and peripheral blood modifications in C57BL mice administered with cyclophosphamide and levan.

The effects of cyclophosphamide (CY) and levan at low (0.1 mg) and high (10 mg) doses (previously found to inhibit and stimulate, respectively, B16 melanoma growth) were studied. in single and combined administration, on the blood and bone marrow of C57BL mice. Very marked changes in the cellular composition of blood and bone marrow were induced by the various treatments. CY caused a sharp depletion of leukocytes in blood and bone marrow followed by a restoration of granulocytes while lymphocytes remained low. Levan caused a sharp dose-dependent depletion in bone marrow lymphocytes. Blood lymphocytes were not affected, however, by the polysaccharide. With the high levan dose, after a temporary granulocytopenia and monocytopenia, prominent granulocytosis was observed. While CY affected equally the different types of cells, levan decreased the number of lymphocytes and erythroblasts to a greater degree than the number of granulocytes. In the combined CY-levan treatments, the low levan dose generally attenuated the suppressive effect of CY, while the high concentration aggravated it.

Animals↗
PubMed1986

[Glomerular filtration and tubular reabsorption of glucose in insulin-dependent diabetes in children].

Although glycosuria is important in the control of diabetes in children, few studies clearly show its significance as compared to glycemia. The aim of the present study was therefore to determine the two parameters that control glucose presence in urine, i.e. glucose glomerular filtration rate (GFR) and tubular reabsorption (JrG). GFR was measured by using a 110 min polyfructosan perfusion in 96 diabetic children and adolescents. The results are as follows: 1) In this population there is a significant correlation (p less than 0.01) between the quantity of glucose in urine and mean glycemia during the test; 2) polyfructosan clearance that reflects GFR in diabetic children without renal complication is 2.11 +/- 0.04 ml/s 1.73 m2, or 126 +/- 2.4 ml/min 1.73 m2 (mean +/- SEM); it is higher than in the reference values already published; 3) JrG is correlated with glucose filtered load (p less than 0.01), GFR (p less than 0.01) and sodium reabsorption (p less than 0.01). The ratio JrG/GFR could be substituted for the classical concept of "renal threshold", as it can be easily measured and may help in interpreting glycosuria in some diabetic children. To conclude, in IDD children, the parameters controlling glycosuria may be studied by a simple method. The clinical value of such renal exploration has still to be determined.

Absorption↗
PubMed1979

Immune response to levan. II. T independence of suppression of cross-reactive idiotypes by anti-idiotype antibodies.

Pretreatment of BALB/c mice with antisera to a cross-reactive idiotype (E109IdX) expressed on many anti-bacterial levan (BL) and anti-inulin (Inu) antibodies leads to a prolonged suppression in production of IdX-bearing molecules in response to BL immunization. There is a comparable suppression in numbers of plaque-forming cells secreting IdX-bearing anti-BL and anti-Inu molecules. Furthermore, spleen cells from anti-E109IdX pretreated mice are unable to transfer to irradiated recipients the ability to produce IdX-bearing anti-BL and anti-Inu antibodies. These results indicate that the suppressive effect is at the precursor level and not simply a clearance of antibodies bearing the IdX. Suppression of IdX production can be achieved by pretreating nu/nu BALB/c mice with anti-E109IdX antibodies. Furthermore, spleen cells from pretreated mice do not inhibit the capacity of spleen cells from normal mice transferred to irradiated recipients to produce E109IdX in response to BL. This indicates that the suppression of IdX production in the anti-BL system is T independent and probably represents direct inhibition of precursors by anti-IdX.

Animals↗
PubMed1986

Different effects of the polysaccharide levan on the oncogenicity of cells of two variants of Lewis lung carcinoma.

A marked difference in sensitivity to the direct effect of the polysaccharide levan on tumour cells was observed between two variants of malignancy of Lewis lung carcinoma: cells of the more malignant variant (3LL-M) were much more sensitive to the drug than those of the less malignant tumour (3LL). A gradual decrease in tumorigenicity following preincubation with increasing levan concentrations was observed with both variants, but statistically significant inhibition was observed at lower levan concentrations with 3LL-M than with 3LL.

Animals↗
PubMed1985

Levan-induced glomerulitis in rabbits: a possible role for direct complement activation in situ.

Since high-molecular-weight levan is known to reduce capillary permeability to large molecules, an experiment was designed to investigate whether this agent may attenuate the glomerulonephritis associated with acute serum sickness in rabbits. The study, in fact, demonstrated an enhancing effect of levan, which caused increased glomerular proliferative changes and leucocyte infiltration and, possibly, increased IgG deposition in this experimental model. In addition, rabbits injected only with levan also demonstrated mild glomerulitis and C3 deposition. In one of four rabbits examined, this was accompanied by a marked fall in the serum level of total haemolysing complement. Levan was demonstrated to cause activation of complement when incubated with normal rabbit serum in vitro. We believe that these findings are best explained on the basis of complement activation in situ by levan in the glomeruli, probably via the alternative pathway, with the resulting inflammatory response. In the case of BSA-injected rabbits, this response is believed to be additive to that of the classical immune complex-mediated complement activation.

Animals↗
PubMedDate not supplied

Efficiency of high permeable membranes in hemodiafiltration in children: an optimal method of purification.

Hemodiafiltration (HDF) combines hemodialysis (HD) and hemofiltration (HF) and so allows an optimal purification by combining diffusive process (low molecular weight compounds) with convective mass transport (middle molecular weight compounds). A high permeable membrane is analysed (clearance, extraction coefficient, sieving coefficient) at 30 min and 150 min session time in HD, HF and HDF conditions. There is not a better elimination of urea in HDF versus HD while HDF allows an optimal elimination of uremic toxins in the range of low and middle molecular weight compounds. A high (optimal?) filtrate flow, with a minimal risk, is given by the formula: QUF = 1/3 QB. Sieving coefficient in HF condition of the other membranes generally employed in pediatric HDF demonstrated a great variability for the cut off.

Blood Flow Velocity↗
PubMed1977

Effects of prolonged administration of high molecular levan on hematological parameters in rabbits.

Rabbits were injected intraperitoneally with 100 mg of high molecular levan, daily for 4--6 weeks. Study of various hematological parameters revealed that the treatment resulted in the following changes: 1. Marked elevation in fibrinogen levels and in the number of platelets. 2. Insignificant changes in the intrinsic and extrinsic clotting mechanisms and in platelet aggregation. 3. Some reduction in the number of circulating RBCs. The findings indicate that levan treatment has no obvious effect on hematologic functions, except for the increase in fibrinogen and platelets and the slight decrease in circulating RBCs.

Animals↗