Effects of antibodies against chicken riboflavin carrier protein on fetal hepatic cell ultrastructure

Pancreatic endocrine tumor with signet ring cell features: a case report with novel ultrastructural observations

The case of a malignant pancreatic endocrine neoplasm with an unusual signet ring cell appearance is reported. The tumor was resected from a 30-year-old man with a 4.0-cm tumor in the body of the pancreas diagnosed by computerized tomographic (CT) scan. The resected tumor had a unique morphology characterized by numerous mucin-negative, signet ring cells, which were argyrophilic and immunoreactive for cytokeratin (CAM 5.2), chromogranin, synaptophysin, neuron specific enolase, and gastrin. Dense-core neurosecretory-type granules and numerous cytoplasmic lamellar inclusions were identified by electron microscopy. These inclusion bodies consisted of multilayered concentric osmiophilic lamellae (myelin figures), which most likely represent an abnormal accumulation of degenerating organelles. Two years later, the patient developed an abdominal recurrence of the tumor, confirming its malignant behavior. This case expands the spectrum of pancreatic endocrine tumors to include an aggressive signet ring cell tumor with a novel ultrastructural basis.

Termination of pregnancy in mice following administration of antibodies to the pentadecapeptide 10-24 of chicken riboflavin carrier protein: identification of a bioneutralizing epitope of chicken riboflavin carrier protein

Our studies have shown that the administration of antibodies to chicken riboflavin carrier protein (cRCP) or disulfide-reduced carboxymethylated cRCP (RCM-RCP) leads to termination of pregnancy in mice. In an attempt to delineate the bioneutralizing epitopes, a combination of chemical modification and predictive methods was used. The results led to the identification of the region 10-24 of cRCP as a potential candidate. A single injection of antipeptide antibodies to pregnant mice on day 11 resulted in 100% pregnancy termination. This was accompanied by a drastic reduction in circulatory progesterone as early as 24 h after the antibody administration. These results thus demonstrate that the amino acid sequence 10-24 of cRCP harbours a bioneutralizing epitope of cRCP.

Studies on the delineation of the antigenic determinants of chicken riboflavin carrier protein (cRCP). Identification of a determinant in the region 10-24 of the protein

As riboflavin carrier proteins play a critical role in the maintenance of pregnancy, studies on the immunology of these proteins have become very relevant. This paper describes our attempts to identify the sequential antigenic determinants of chicken riboflavin carrier protein (cRCP). Potential surface oriented regions of cRCP were identified by constructing acrophilicity and hydrophilicity profiles of the protein. Of the three regions identified, the pentadecapeptide 10-24 of cRCP forms the subject of the present study. The pentadecapeptide amide was synthesized by solid phase synthesis using Fmoc chemistry. Immunization of rabbits with the peptide-diphtheria toxoid conjugate elicited high titres of the antipeptide antibodies, revealing the high immunogenicity of the peptide. The antipeptide antibodies bound to both cRCP and reduced carboxymethylated RCP (RCM-RCP). Antisera to RCM-RCP showed significant binding to the peptide showing thereby that the region 10-24 of cRCP is perhaps one of the major epitopes of RCM-RCP. Thus, the studies have resulted in the identification of the region 10-24 as an antigenic determinant of cRCP.