Germline mutations detected in the von Hippel-Lindau disease tumor suppressor gene by Southern blot and direct genomic DNA sequencing.
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Amino Acid Substitution↗
Biomedical subjects
G Akerström
Publications and source records attributed to G Akerström.
Limited tumor involvement found at multiple endocrine neoplasia type I pancreatic exploration: can it be predicted by preoperative tumor localization?
Radiologically demonstrable pancreatic endocrine tumors are a frequent requirement for exploration in patients with multiple endocrine neoplasia type I (MEN-I). Such delayed intervention is accompanied by a 30% to 50% incidence of pancreatic endocrine metastases. This study explores biochemical tumor markers and operative findings in relation to preoperative pancreatic radiology in 25 MEN-I patients. They underwent pancreatic surgery with (n = 19) or without (n = 6) radiologic signs of primary tumor and absence of metastases upon conventional examination, including OctreoScan testing (n = 10). Biochemical diagnosis required an increasing elevation of at least two independent pancreatic tumor markers. Tumor diameters averaged 1.1 cm (0-5 cm) and 0.9 cm (0.2-1.5 cm) in the patients with and without positive preoperative radiology, respectively. These investigations never displayed more than one of the consistently multiple tumors, and the results were falsely positive in 26%. Preoperatively unidentified regional or hepatic metastases were found at surgical exploration in 26% of patients with radiologic localization and in none of the others. Limited pancreatic tumor involvement necessitated intraoperative absence of metastases and pancreatic lesions </= 1 cm in diameter on palpation, intraoperative ultrasonography, and microscopy. It occurred in 37% and 50% of the patients with and without radiologic tumor localization, respectively. The number of positive tumor markers was similar for patients with limited and major disease (2.3 vs. 2.7), whereas four or more such markers were found in all those with malignancies. The mean marker level was higher in patients with radiologically demonstrable tumors and lower in those with limited disease, but with a substantial overlap. OctreoScan testing was negative in all cases with limited disease and was the single most sensitive method (75%) in the others. Limited pancreatic disease could not be identified preoperatively, and the present means of biochemical pancreatic tumor identification invariably involved the presence of at least one lesion >/= 7 mm in diameter. Conventional pancreatic imaging is insensitive and nonspecific for recognizing even substantial pancreatic tumors associated with MEN-I.
Adult↗
Vitamin D receptor gene polymorphism and parathyroid calcium sensor protein (CAS/gp330) expression in primary hyperparathyroidism.
Calcitriol, via its receptor (VDR), inhibits parathyroid hormone (PTH) secretion and cell proliferation. Physically linked polymorphic VDR alleles denoted b,a, and T, comprise a novel risk factor for postmenopausal primary hyperparathyroidism (pHPT) by their presumed coupling to reduced VDR expression. This study examines VDR gene polymorphisms, parathyroid calcium-regulated cytoplasmic calcium concentrations ([Ca2+]i) and parathyroid expression of a calcium sensor protein (CAS/gp330). Genomic DNA was obtained from 66 postmenopausal women with pHPT and 66 age-matched female controls. Polymorphic VDR alleles were detected after polymerase chain reaction (PCR) and restriction digestion. Cryosections of pathologic parathyroid glands from 41 of the patients were immunostained with a monoclonal anti-CAS/gp330 antibody. Homozygosity for the VDR alleles b, a, and T was overrepresented in pHPT (p < 0.01-0.05) but did not couple to ED50 for calcium-regulated [Ca2+]i. The enlarged parathyroid glands possessed heterogeneous down-regulation of CAS/gp330. This down-regulation was the least conspicuous in the BBgenotype, and these few patients generally had larger parathyroid lesions (p < 0. 05). The VDR haplotype baTis a risk factor for pHPT possibly by hampering the regulatory actions of calcitriol. In contrast the BAt haplotype seems to be underrepresented in pHPT and to couple to larger parathyroid lesions as well as less deranged CAS/gp330 expression and parathyroid cell function. HPT in these individuals may relate to genetic events principally altering the regulation of cell proliferation, rather than calcium sensing of the parathyroid cells.
Aged↗
Double parathyroid adenoma, a clinically nondistinct entity of primary hyperparathyroidism.
Double parathyroid adenoma (DA) has been suggested to be a clinically distinct entity of primary hyperparathyroidism (HPT). Altogether 659 patients with sporadic primary HPT were analyzed retrospectively by evaluating consecutive primary operations for more than three decades. Patients with postoperatively persistent HPT and those with incomplete medical, operative, or histologic records were disregarded. The mean age (+/- SD) at surgery was 60.9 +/- 12.7 years; 78% of the patients were female; and the duration of postoperative follow-up averaged 7.8 +/- 7.2 years. DA, defined as two enlarged parathyroid glands, was found in 77 patients (12%). Enlargement of a single gland (SA) or three or more glands (MA) occurred in 80% and 8%, respectively. DAs were bilateral in 72% of patients, and the weight of the two glands differed by 317 +/- 407 mg. The three histologic subgroups of patients exhibited no significant discrepancy with respect to age, classic symptoms of HPT, proportion of overtly asymptomatic individuals, or parathyroid tissue weight. A lower female predominance and extent of hypercalcemia and higher preoperative serum creatinine level occurred with DA and MA compared to SA. SA and DA differed from MA with respect to variably strong trends to lower postoperative incidences of recurrent HPT and hypoparathyroidism. DA seems to comprise an underrated histologic cause of HPT, which is eligible for a conservative operative approach. Clinical characteristics consistent with a distinct entity of sporadic primary HPT were not seen.
Adenoma↗
A family with hereditary extra-adrenal paragangliomas without evidence for mutations in the von Hippel-Lindau disease or ret genes.
OBJECTIVES: To characterize a family with hereditary paraganglioma, and to search for germline mutations in the von Hippel-Lindau disease (VHL) tumour suppressor gene and the ret proto-oncogene. DESIGN: Patient records and histopathological reports were reviewed. Available tumour samples were reinvestigated using immunohistochemical techniques. The VHL gene was investigated by single strand conformational polymorphism analysis of PCR products amplified from exons 1, 2 and 3 and the 3' untranslated region. The ret gene was analysed by amplifying and sequencing exons 10, 11 and 16. PATIENTS: A family with paragangliomas in three consecutive generations was investigated. RESULTS: The affected individuals were found to have multiple extra-adrenal paragangliomas. All three affected individuals had retroperitoneal tumours, and two also had paraganglioma in the neck. No mutations of the VHL or ret genes were detected. CONCLUSIONS: The described family may represent a novel dominantly inherited neuroendocrine tumour syndrome.
Adolescent↗
Regulation of gp330/megalin expression by vitamins A and D.
BACKGROUND: A membrane-bound 550-kD Ca2+-binding glycoprotein belonging to the low-density lipoprotein (LDL) receptor superfamily has recently been identified as a putative calcium-sensing molecule. This molecule, known as gp330/megalin, is among several tissues present in the proximal tubule, parathyroid and placental cytotrophoblasts, in which a Ca2+-sensing function has been demonstrated. METHODS: Regulation of mRNA and protein expression of gp330/megalin were studied in a recently established cell line derived from rat kidney proximal tubule cells (IRPTCs), in human JEG-3 cells and in the mouse embryonal carcinoma cell line F9. RESULTS: In IRPTCs, quantification of mRNA and protein expression demonstrated two- to five-fold increases after addition of 10(-6) mol L(-1) all-trans-retinoic acid, 9-cis-retinoic acid or 1,25-dihydroxyvitamin D3, alone or in combination. Similarly, an increase in gp330/megalin mRNA expression was seen in JEG-3 cells cultured with vitamin D and retinoids, as well as when F9 cells were differentiated by incubation with retinoic acid and cAMP. The IRPTCs were immortalized by viral infection with the SV40 genome preceded by a temperature-sensitive promoter. Thus, by culture of the cells at 41 degrees C, SV40 genome transcription is inhibited and the IRPTC phenotype is reversed towards non-infected proximal tubule cells. At 41 degrees C, gp330/megalin mRNA expression was significantly increased compared with cells incubated at 34 degrees C. CONCLUSION: The results indicate a correlation between exposure to retinoic acid or vitamin D or induction of cell differentiation (by retinoic acid/cAMP in F9 cells or inhibition of SV40 transcription in IRPTCs) and an increase in gp330/megalin protein and mRNA expression.
Animals↗
Characterization of the human Megalin/LRP-2 promoter in vitro and in primary parathyroid cells.
The gp330/Megalin/LRP-2 protein belongs to the low-density lipoprotein receptor gene family and is believed to function as an endocytic receptor for the uptake of lipoproteins and many other ligands. Other functions of this protein may include a role in calcium sensing in the parathyroid glands and other tissues. In order to study the transcriptional regulation of the human LRP-2 gene, a clone containing the 5'-flanking region was isolated from a genomic DNA library, and a transient transfection protocol for primary bovine parathyroid cells was established. RNA mapping techniques located the transcriptional start site 136 bp upstream of the initiation codon. Transient expression in several cell types, including primary parathyroid cells, and in vitro transcription in HeLa cell nuclear extracts showed that sequences between -120 and -35 were important for activated transcription. This region contains consensus binding sites (GC boxes) for transcription factor Sp1. Mutation of the GC boxes abolished binding of Sp1 in vitro and resulted in reduced transcription in vitro and in transfected cells. Furthermore, Sp1 stimulated transcription when tethered to the LRP-2 core promoter through a heterologous DNA-binding domain. Through site-directed mutagenesis, we identified a novel atypical TATA element with the sequence TAGAAAA. Intriguingly, this sequence motif was shown previously not to mediate transcription in a systematic mutational analysis of the TATA motif. Possible roles of this novel TATA element in the regulation of transcription initiation are discussed. The isolation and characterization of the LRP-2 promoter and the 5'-flanking region and the establishment of a transient expression assay in primary parathyroid cells will facilitate studies on the regulatory mechanisms of the LRP-2 gene and of other genes expressed in the parathyroid glands.
Animals↗
Childhood Graves' disease--remission rate and risk factors.
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Child↗
Vitamin D receptor (VDR) and parathyroid hormone messenger ribonucleic acid levels correspond to polymorphic VDR alleles in human parathyroid tumors.
Calcitriol, via its receptor (VDR) is a main regulator of PTH secretion and parathyroid cell proliferation. Recently, marked overrepresentation of the polymorphic VDR alleles b, a, and T was found in patients with primary hyperparathyroidism (pHPT), which suggests pathogenic importance in the disease. Using the ribonuclease protection assay, relative VDR and PTH messenger ribonucleic acid (mRNA) levels of parathyroid adenomas from 42 patients with sporadic pHPT were related to these VDR polymorphisms. The tumors of patients homozygous for the b, a, or T alleles demonstrated significantly lower VDR and higher PTH mRNA levels than those exhibiting the BB, AA, or tt genotypes (P < 0.0001-0.02), whereas heterozygotes had intermediate values. A similar discrepancy was found when comparing the baT and non-baT haplotypes (0.042 +/- 0.005 vs. 0.064 +/- 0.004 for VDR; 34.4 +/- 3.7 vs. 21.6 +/- 2.2 for PTH; both P < 0.005). The lower VDR mRNA levels associated with the b, a, and T alleles may affect the calcitriol-mediated control of parathyroid function and thereby contribute to the development of sporadic pHPT.
Adenoma↗
Parathyroid MEN1 gene mutations in relation to clinical characteristics of nonfamilial primary hyperparathyroidism.
Biochemical signs and severity of symptoms of primary hyperparathyroidism (pHPT) differ among patients, and little is known of any coupling of clinical characteristics of nonfamilial pHPT to genetic abnormalities in the parathyroid tumors. Mutations in the recently identified MEN1 gene at chromosome 11q13 have been found in parathyroid tumors of nonfamilial pHPT. Using microsatellite analysis for loss of heterozygosity (LOH) at 11q13 and DNA sequencing of coding exons, the MEN1 gene was studied in 49 parathyroid lesions of patients with divergent symptoms, operative findings, histopathological diagnosis, and biochemical signs of nonfamilial pHPT. Allelic loss at 11q13 was detected in 13 tumors, and 6 of them demonstrated previously unrecognized somatic missense and frameshift deletion mutations of the MEN1 gene. Many of the detected mutations would most likely result in a nonfunctional menin protein, consistent with a tumor suppressor mechanism. Clinical and biochemical characteristics of HPT were apparently unrelated to the presence or absence of LOH and the MEN1 gene mutations. However, the demonstration of LOH at 11q13 and MEN1 gene mutations in small parathyroid adenomas of patients with slight hypercalcemia and normal serum PTH levels suggest that altered MEN1 gene function may also be important for the development of mild sporadic pHPT.
Adenoma↗
Major histocompatibility complex class II expression and parathyroid autoantibodies in primary hyperparathyroidism.
BACKGROUND: Autoimmune diseases are characterized by induced parenchymal expression of major histocompatibility complex (MHC) class II antigens and circulating autoantibodies directed toward surface structures on the target cells. MHC class II expressions can be modified by viral infections of potential pathogenic importance in autoimmune reactions. Primary hyperparathyroidism exhibits incompletely clarified cause. METHODS: With cryosections, human parathyroid glands were stained with monoclonal antibodies to MHC class II antigens according to a peroxidase-antiperoxidase technique. Human parathyroid adenoma tissue transplanted to nude mice and rat parathyroid glands was tested with serum from patients with hyperparathyroidism and control subjects. RESULTS: Induced MHC class II expression was demonstrated on parathyroid parenchymal cells in 13 of 54 adenomatous and eight of 23 hyperplastic glands of patients with primary hyperparathyroidism. This reactivity was absent in 12 normal glands, nine normal-sized glands associated with the adenomas, and 17 enlarged glands of patients with hyperparathyroidism caused by uremia. Staining of parathyroid tissue was found with serum from 27 of 38 patients with primary hyperparathyroidism, whereas this reactivity was absent on rat thyroid and pancreatic tissue, as well as with control sera. CONCLUSION: The concurrent induction of MHC class II antigen expression and c circulating antiparathyroid autoantibodies in 16 or 38 patients with primary hyperparathyroidism suggests hitherto unrecognized immunologic involvement in this disease.
Adenoma↗
Case-control study on symptoms and signs of "asymptomatic" primary hyperparathyroidism.
BACKGROUND: Symptoms, signs, and treatment of mild primary hyperparathyroidism (HPT) are controversial. METHODS: One hundred two patients with HPT and matched controls were recruited from 5202 females attending population-based mammography screening at age 55 to 75 years. Patients' total serum calcium averaged 10.40 +/- 0.564 mg/dL and intact serum parathyroid hormone 58 +/- 33 ng/L. All patients lacked knowledge of their disease. Questions revealed traditional symptoms of HPT in 24% of cases and 43% of controls (P = .01). All individuals underwent the same biochemical analyses, bone mass determination, and questionnaires on symptoms, illnesses, medications, and background variables. RESULTS: Patients with HPT had more psychic complaints (P = .03 to .007) of lassitude, fatigue, irritability, and lack of sexual and emotional interests. They had lower bone density in total body, spine, and hip (P = .008 to .0004) and higher serum alkaline phosphatase, cholesterol (very-low-density lipoprotein), triglycerides (total, very-low-density lipoprotein), glucose, urate, and hemoglobin values (P = .02 to .0001). Patients visited physicians more often (P = .008) and had more antihypertensive therapy (P = .02). CONCLUSIONS: Mild, "asymptomatic" HPT in patients unaware of their disorder displays significant psychic symptoms, bone loss, and risk factors of cardiovascular disease.
Aged↗
Primary and reoperative parathyroid operations in hyperparathyroidism of multiple endocrine neoplasia type 1.
BACKGROUND: Operation and reoperation for hyperparathyroidism in multiple endocrine neoplasia type 1 (MEN 1) is controversial regarding surgical strategy, preoperative localization, and biochemical indexes of recurrence. METHODS: Fifty patients with MEN 1 with hyperparathyroidism were followed up 2 to 27 years after subtotal (SPX; n = 35) or total parathyroidectomy with forearm autografiing (TPX; n = 15), including 24 who underwent 28 reoperations because of persistent or recurrent hyperparathyroidism. RESULTS: Persistent or recurrent hyperparathyroidism was seen in 66% and 20% of patients after SPX involving extirpation of at least 3 glands and TPX, respectively, and 100% after single-gland excision as a primary procedure. After reoperation, hypercalcemia was reversed in 33% of patients by SPX and 61% by intended TPX procedures. All patients received vitamin D substitution after TPX, but restricted thyroid function allowed withdrawal in all but 10 patients (36%). Intact serum parathyroid hormone levels in nongrafted and grafted arms rose with time, but only exceptional ratios localized graft recurrence. Localization of recurrent hyperparathyroidism was achieved with 11C-labeled methionine positron emission tomography. CONCLUSION: MEN 1 hyperparathyroidism has a high risk of recurrence, and operation may include primarily SPX of at least 3 glands or TPX, although the latter includes a higher risk of long-term hypoparathyroidism. Reoperation should involve TPX with recognition of the enhanced recurrence rate in individuals with postoperative hyperparathyroidism.
Adolescent↗
Intraoperative gamma detection reveals abdominal endocrine tumors more efficiently than somatostatin receptor scintigraphy.
BACKGROUND: [(111)In]-diethylenetriamine pentaacetic acid (DTPA)-D-[Phe1]-octreotide (OctreoScan, Mallinckrodt Medical, Petten, The Netherlands), combined with single photon emission computed tomography (SPECT), has limited possibilities to detect small abdominal endocrine tumors. This study explores the efficacy of OctreoScan and a newly developed handheld gamma detector probe (H-probe2) for the localization of neuroendocrine abdominal tumors. METHODS: Twenty-one patients with endocrine pancreatic or midgut carcinoid tumors were given 100-200 megabecquerels (MBq) [(111)In]-DTPA-D-[Phe1]-octreotide and underwent preoperative SPECT examination, after which time surgery was undertaken within 24-48 hours. Intraoperatively the radioactivity of tumors and normal tissues was measured with the H-probe2 connected to a portable personal computer. Resected intestinal specimens of ten patients with carcinoid tumors were examined by gamma camera ex vivo. Biopsies of all tumors subsequently were investigated in a wellcounter and by routine histopathology. RESULTS: Disregarding liver metastases, a total of 34 of 60 abdominal tumors were detected by SPECT; however, SPECT failed to visualize any tumor < 9 mm. The shielding of the manual probe allowed intraoperative examination despite the substantial radiation energy of (111)In. The H-probe2 detected 91% of the tumors investigated, and these included all those > 5 mm. In the wellcounter the H-probe2-detected tumors exhibited 4.7-157.7 times higher radionuclide uptake than the surrounding normal tissues. The gamma camera analysis detected 68% of tumors in the resected specimens. CONCLUSIONS: The intraoperative H-probe2 examination provided substantial improvement in the detection of small endocrine lesions accumulating [(111)In]-DTPA-D-[Phe1]-octreotide and all lesions with a size > 5 mm in greatest dimension could be identified.
Adult↗
A gamma detector probe with ex vivo detection of carcinoid tumors superior to intraoperative palpation.
BACKGROUND: Despite the generally successful scintigraphic detection of endocrine tumors with [(111)In]-DTPA-D-[Phe1]-octreotide (OctreoScan, Mallinckrodt Medical, Petten, The Netherlands), its intraoperative application awaits the development of suitable gamma detectors. This study describes a novel probe (H-probe2) and its ex vivo efficacy for the detection of midgut carcinoid tumors. METHODS: The probe measures 180 mm x 24 mm, and contains a bismuth germinate crystal connected to a photomultiplicator tube, a lead shield, and a tantalum collimator with an angled, 3-mm wide opening. It was characterized in a test bench utilizing solublilized (111)In and 99mTc, and 8 fresh operative specimens containing 26 histologically verified midgut carcinoid tumors (2-40 mm) from patients exposed to OctreoScan. Measurements were made at 2.5-mm intervals over the entire specimens and presented three dimensionally. RESULTS: The test bench analysis supported efficient shielding, and a total collimation of 27 degrees for (111)In and 20 degrees for 99mTc. In addition to 18 palpable tumors, 4 of 6 surgically occult tumors (2-3 mm in dimension) could be discovered with H-probe2. Small tumors in close apposition to a large tumor could not be separated. Wellcounter examination showed that tumors detected with the H-probe2 exhibited 1.7-84.1 times higher radionuclide uptake than the surrounding normal tissue. CONCLUSION: Ex vivo analysis of H-probe2 supported detection of tumors inaccessible to surgical palpation, but its clinical efficiency awaits intraoperative evaluation.
Carcinoid Tumor↗
Aberrantly expressed cytokeratin 1, a tumor-associated autoantigen in papillary thyroid carcinoma.
Papillary thyroid carcinoma (PTC) is a somewhat puzzling disease, combining a propensity to metastasize with an indolent clinical course. The often pronounced T cell-dominated inflammatory infiltrate seen in PTC tumors has prompted us to search for signs of a tumor-induced immune response. In previous studies, we have demonstrated large tumor-specific deposits of IgG and complement in PTC tissue and isolated a putative target antigen. This investigation examines the presence of autoantibodies to cytokeratin 1, a high m.w. cytokeratin normally expressed only in suprabasal keratinocytes, in the serum and tumor tissue of PTC patients. Using immunoprecipitation and Western blot, cytokeratin 1-reactive autoantibodies were demonstrated in 80% of the PTC sera tested, and tumor-derived antibodies were shown to precipitate cytokeratin 1. Using immunohistochemistry, cytokeratins 1 and 10 were found in a large proportion of PTC tumors (39/44) but were absent from normal thyrocytes of most PTC-bearing glands. Our results indicate that this protein is expressed aberrantly in neoplastic cells and is immunogenic in this context.
Autoantibodies↗
A complex nine base pair deletion in RET exon 11 common in sporadic medullary thyroid carcinoma.
Genetic alteration of the RET proto-oncogene is associated with multiple endocrine neoplasia type 2A and 2B (MEN 2A and MEN 2B), familial medullary thyroid carcinoma (FMTC) and Hirschprung's disease. Oncogenically activated RET has also been demonstrated in sporadic medullary thyroid tumors, which in some cases show somatic missense mutations. We have recently described a complex 9 bp deletion in RET exon 11 in a single case of sporadic MTC. In order to determine the prevalence of this mutation among sporadic MTC tumors, we have now analysed 15 cases and five normal controls by PCR-based nonradioactive single-strand conformational polymorphism analysis (PCR-SSCP) and fragment size analysis of exon 11. DNA was extracted from microdissected tumor tissue or normal cells and subjected to nested PCR prior to analysis. A markedly divergent SSCP pattern and a PCR fragment 9 bp shorter than normal were demonstrated in 14 of the 15 MTC tumors. Sequencing revealed the deletion of nine bases encompassing a key cysteine at codon 634, often altered in MEN 2A. Four lymphocyte controls and normal thyroid tissue from one patient failed to show the deletion. Several factors in the DNA sequence environment immediately surrounding the deletions, including an extended inverted repeat, several direct repeats and a so-called symmetric element suggest that the deletional events may be non-random.
Base Sequence↗
Vitamin D receptor alleles b, a, and T: risk factors for sporadic primary hyperparathyroidism (HPT) but not HPT of uremia or MEN 1.
Polymorphisms in the vitamin D receptor (VDR) gene have been hypothezised to interfere with VDR expression. VDR alleles (Bb, Aa and Tt) were examined in 254 Caucasian patients with sporadic primary hyperparathyroidism (spHPT, n = 206), HPT of multiple endocrine neoplasia type 1 (MEN-1; n = 17), and HPT of uremia (n = 31). In comparison to age- and sex-matched controls, the b, a and T alleles were overrepresented in 100 menopausal females with spHPT (p = 0.006-0.0004), equivalent to an odds ratio of 2.6-3.4 for spHPT in homozygotes for the b, a and, T alleles. The association between VDR genotypes and spHPT was restricted to female patients and those with parathyroid adenoma (p = 0.0006-0.0001), whereas HPT of MEN 1 and uremia seemed unrelated to the VDR polymorphisms (p = 0.26-0.96). The results suggest that the VDR alleles b, a, and T are novel risk factors in the essentially uncharacterized pathogenesis of spHPT.
Alleles↗