Pseudotumor cerebri and hypothyroidism

A 38-year-old obese woman with concurrent hypothyroidism and pseudotumor cerebri was monitored with serial thyroid function tests and CSF pressure determinations during levothyroxine sodium replacement therapy. Following normalization of the patient's thyroid status, assessed by both clinical and chemical indexes (serum thyroxine level, 1.5 to 11.0 micrograms/dL; serum thyrotropin level, 128 to 1.5 micro units/mL), intracranial hypertension persisted for more than four months. After weight loss, acetazolamide therapy, and intermittent CSF drainage failed to produce remission, glucocorticoid therapy was associated with prompt, sustained resolution of the pseudotumor cerebri. Contrary to previous reports, this patient's clinical course suggests that thyroid hormone deficiency and pseudotumor cerebri are not causally related.     

Isolation and characterization of rabbit single chain antibodies to human Reg Ialpha protein

To investigate the role of Reg Ialpha in human inflammatory bowel disease (IBD), we made two phage-displayed single chain variable fragment (scFv) libraries from rabbits immunized with recombinant or native human Reg Ialpha. After one to three rounds of panning, we were able to isolate phage-displaying scFvs, which bound to human Reg Ialpha. Anti-Reg Ialpha scFvs from both libraries showed similar immunoreactivity to different processed forms of the protein. Despite several DNA fingerprint patterns among these clones, their deduced amino acid sequences are highly homologous with 100% identity in the complementarity-determining regions (CDRs) of the variable segment of heavy chain (VH) region and a small variation in the CDR1 of the variable segment of light chain (VL) region. We also expressed and purified soluble myc-tagged or glutathione S-transferase (GST) fusion scFv proteins from bacteria. Immunohistochemical studies using one of our anti-Reg Ialpha scFv antibodies showed prominent staining in the metaplastic Paneth cell population and light staining in the lamina propria. This scFv antibody is now being used for studies of the role of Reg Ialpha in human IBD.     

Methylation of the thyroid-stimulating hormone receptor gene in epithelial thyroid tumors: a marker of malignancy and a cause of gene silencing

Thyroid-stimulating hormone receptor (TSHR) expression is frequently silenced in epithelial thyroid cancers associated with decreased or absent TSH-promoted iodine uptake. To study the underlying molecular mechanism of decreased TSHR expression, we examined the methylation status of the TSHR gene promoter by sequencing bisulfite-treated DNA from thyroid tumors. After identification of methylated sites by sequencing bisulfite-treated DNA, we used methylation-specific polymerase chain reaction and found frequent CpG methylation in papillary thyroid cancer (23 of 39 patients; 59%) and follicular thyroid cancers (7 of 15 patients; 47%). In contrast, we saw no methylation in normal thyroid tissues and benign adenomas (0 of 8 patients; 0%). In human thyroid tumor cell lines, we observed that TSHR was normally expressed at the protein and mRNA level in cells where the TSHR gene was unmethylated, whereas it was silenced in cell lines where the TSHR promoter was hypermethylated. Treatment of the latter cells with a demethylating agent partially restored TSHR expression. We thus demonstrate aberrant methylation of human TSHR as a likely molecular pathway responsible for the silencing of this gene in thyroid cancers. We propose that methylation of TSHR may provide a novel diagnostic marker of malignancy and a basis for potential use of demethylating agents in conjunction with TSH-promoted radioiodine therapy for epithelial thyroid cancers.     

BRAF mutation in papillary thyroid carcinoma

The BRAF gene has been found to be activated by mutation in human cancers, predominantly in malignant melanoma. We tested 476 primary tumors, including 214 lung, 126 head and neck, 54 thyroid, 27 bladder, 38 cervical, and 17 prostate cancers, for the BRAF T1796A mutation by polymerase chain reaction (PCR)-restriction enzyme analysis of BRAF exon 15. In 24 (69%) of the 35 papillary thyroid carcinomas examined, we found a missense thymine (T)-->adenine (A) transversion at nucleotide 1796 in the BRAF gene (T1796A). The T1796A mutation was detected in four lung cancers and in six head and neck cancers but not in bladder, cervical, or prostate cancers. Our data suggest that activating BRAF mutations may be an important event in the development of papillary thyroid cancer.     

The role of positron emission tomography/computed tomography in the management of recurrent papillary thyroid carcinoma

OBJECTIVES/HYPOTHESIS: The aim of the study was to evaluate the role of combined positron emission tomography/computed tomography (PET/CT) fusion imaging in the detection and management of recurrent papillary thyroid cancer. STUDY DESIGN: A retrospective analysis of 33 patients with suspected recurrent papillary thyroid carcinoma who had undergone PET/CT was performed. PET/CT was compared with standard imaging techniques in each patient to determine whether PET/CT contributed to the therapeutic management plan. Histopathological findings were correlated to PET/CT in patients who underwent surgery. METHODS: The senior author reviewed the charts of 33 patients with recurrent papillary thyroid carcinoma to determine the impact PET/CT had on management. PET/CT was compared with conventional imaging results. In surgical patients, PET/CT was compared with histopathological findings to determine its sensitivity, specificity, accuracy, positive predictive value, and negative predictive value. RESULTS: In 67% of the cases (22 of 33), PET/CT supplied additional information that altered or confirmed the management plan. Twenty of 33 patients underwent surgery with 36 sites assessed by histopathological analysis. PET/CT correlated with histopathological findings in 25 of 36 distinct anatomical sites, with an accuracy of 70%. The sensitivity of PET/CT in identifying recurrence was found to be 66%, with a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 27%. CONCLUSION: Combined PET/CT fusion scanning was most useful in the detection and management of recurrent papillary thyroid cancer in patients who had average thyroglobulin levels greater than 10 ng/mL and when the tumor no longer concentrated radioactive iodine. In 100% of the cases in which PET/CT localized a region suspicious for malignancy, histopathological analysis confirmed the results. When PET/CT is positive, it is a powerful tool for predicting exact locations of recurrent papillary thyroid cancer, thus making it a reliable guide for surgical planning. PET/CT is a supplement to conventional imaging and fine-needle aspiration in the workup of recurrent papillary thyroid cancer. A negative finding on PET/CT is not sufficiently reliable to preclude further investigation and treatment.     

When to treat mild hypothyroidism.

The availability and wide acceptance of TSH assays for primary assessment of thyroid function has led to the recognition that mild thyroid hormone deficiency is characterized by elevation of the serum TSH concentration despite a normal free thyroxine level. Other conditions can also cause isolated serum TSH elevation, and these conditions can be distinguished from mild thyroid failure usually based-on clinical and circumstantial observations alone. Thyroxine treatment of patients with mild hypothyroidism has been shown in most, but not all, clinical trials to lower atherogenic lipid levels and relieve certain somatic and neuropsychiatric symptoms. Such treatment also prevents the progression to overt hypothyroidism, which is particularly likely in patients who are older, who have circulating thyroid autoantibodies, or who have a serum TSH greater than 10 mU/L. After the optimal thyroxine dose has been defined, long-term monitoring of patients with an annual clinical evaluation and serum TSH measurement is appropriate. The high prevalence of mild hypothyroidism, particularly in older women, and its subtle clinical presentation have led some authorities to recommend a low threshold for case-finding or routine population screening for the disorder.     

Production and characterization of a monoclonal antibody reactive with a specific neoantigenic determinant (comprising B beta 54-118) in degradation products of fibrin and of fibrinogen

Balb/c mice were immunized with a mixture of fibrin degradation products (XDPs) prepared by complete lysis of a human blood clot by tissue-type plasminogen activator and purified by immunoaffinity chromatography. Spleen cells of the mice were fused with P3 X 63 Ag 8653 myeloma cells. A clone (FDP 14) was selected that produces monoclonal antibodies (MoAbs) of the IgG1 kappa type that react with a neoantigenic determinant exposed in these XDPs, but not in intact fibrinogen or in fibrin monomers. Furthermore, the MoAb is reactive with some pure, individual degradation products of fibrinogen (fragments X, Y, E, and the N-terminal disulphide knot) and with the fibrinogen B beta-chain but not with A alpha- and gamma-chains or with fragments D, FCB-2 and FCB-3. Comparison of the known primary structures of these fibrinogen fragments indicates that the stretch B beta 54-118 comprises at least an important part of the epitope recognized by FDP-14. Apparently, this stretch contributes importantly to a neoantigenic determinant that is not functional in intact fibrinogen and fibrin monomer and that can be made functional by reduction of fibrinogen, or by digestion with plasmin or CNBr.