The effects of antiserum to human chorionic gonadotropin (HCG) on growth and endocrine function of human choriocarcinoma serially transplanted in the cheek pouch of the hamster and maintained in tissue culture were examined. Anti-HCG serum given in amounts sufficient to neutralize the biological effect of the HCG secreted by the tumor significantly reduced tumor size. Since tumor growth was not enhanced by HCG administration or by ovariectomy, the antitumor effect could not be attributed to neutralization of the hormonal effects of the HCG. Anti-HCG serum had no effect on the growth of choriocarcinoma cells in vitro , suggesting that a host factor was required for the in vivo effect of the antiserum on tumor growth.
Plasma TSH levels were measured in goitrous young males living in an area of moderate iodide deficiency in the Egyptian desert (New Valley). Nongoitrous young males living in an area of the same desert where water iodide concentrations were higher (Siwa oases) and a group of normal American subjects served as controls. Plasma TSH levels were higher in the New Valley males than in either control group. Serum PBI values and urinary iodide excretions were lower in the goitrous New Valley subjects than in the Siwa controls. These data support the hypothesis that, at least in some instances, an increase in circulating TSH is a contributing factor to endemic goiter formation in subjects living in areas of mild to moderate iodide deficiency.
The possibility that a complete complement system might be necessary for response to long-acting thyroid stimulator (LATS) in mice has been tested. DBA/2 mice which have a total absence of the fifth component of complement (C′5) were injected with decomplemented plasma known to contain LATS. The presence of a complete complement system was not necessary for LATS activity and the response was not increased by passive transfer of a complete complement source. (Endocrinology81: 671, 1967)
The variant-specific surface proteins (VSPs) of the ancient protist Giardia duodenalis(syn.: Giardia intestinalis, Giardia lamblia) are cysteine- and threonine-rich polypeptides that can vary considerably in sequence and size. In the present study, we have purified a VSP (VSP4A1, formerly called CRISP-90) from a cloned Giardiaisolate, derived from a sheep, by Triton X-114 phase partitioning and anion-exchange chromatography. Analysis of the purified VSP4A1 showed that this protein is post-translationally modified with both glycans and lipid. The glycans of VSP4A1 were detected and partially characterized by (1) compositional analysis, which indicated the presence of GlcNAc and Glc (0.5 and 1.0 mol/mol of protein respectively), and (2) the specific labelling of VSP4A1 with galactosyltransferase/UDP-[3H]Gal. The glycans were released by β-elimination, suggesting that they are O-linked to the protein. Bio-Gel P4 chromatography of the released galactosylated glycans and further compositional analysis suggested that the major glycan on the VSP is a trisaccharide with Glc at the reducing terminus. These and other results indicate the absence of any N-linked glycans on the VSP and suggest instead that it is elaborated with a novel type of short O-linked glycan. Compositional analysis and radiolabelling experiments also indicated that VSP4A1 is modified with covalently linked palmitate (1 mol/mol of protein). Hydroxylamine treatment at neutral pH of [3H]palmitate-labelled VSP4A1 indicated that the acyl chain may be attached by a thioester linkage. A likely location for the lipid modification appears to be in the region of the C-terminal domain where it may facilitate association of the protein with the plasma membrane.
