Quadrupolar ordering in LaMnO3 revealed from scattering data and geometric modeling

Many strongly correlated materials display quadrupolar (Jahn-Teller) distortion of the local octahedral structural units. It is common for these distortions to be observed by probes of local structure but absent in the crystallographic average structure. The ordering of these quadrupoles is important in determining the properties of manganites and cuprates, and the nature of the disorder in these structures has been an unsolved problem. We combine high resolution scattering data and novel geometrical modeling techniques to obtain a detailed picture of the local atomic structure, and also to extract the quadrupolar order parameter associated with the distorted octahedra. We show that in LaMnO3, quadrupoles undergo a strong first-order phase transition at 730 K, but with nonzero order parameter remaining in the high-temperature phase.

Geometric simulation of perovskite frameworks with Jahn-Teller distortions: applications to the cubic manganites

A new approach is presented for modeling perovskite frameworks with disordered Jahn-Teller (JT) distortions and has been applied to study the elastic response of the LaMnO3 structure to defects in the JT ordering. Surprisingly, antiphase domain boundary defects in the pattern of ordered JT octahedra, along the [110] and [110] bonding directions, are found to produce 1D stripe patterns rotated 45 degrees along a* directions, similar to stripe structures observed in these systems. Geometric simulation is shown to be an efficient and powerful approach for finding relaxed atomic structures in the presence of disorder in networks of corner-shared JT-distorted octahedra such as the perovskites. Geometric modeling rapidly relaxes large supercells (thousands of octahedra) while preserving the local coordination chemistry, and shows great promise for studying these complex systems.

The future of surgical research: the role of the American College of Surgeons Oncology Group

The American College of Surgeons Oncology Group (ACOSOG) was established in 1997; it is funded by the National Cancer Institute (NCI) and American College of Surgeons (ACS) for the purpose of conducting multicenter phases II and III clinical trials in the field of surgical oncology. After eight years, ACOSOG has successfully completed seven trials and has five studies currently open to accrual for patients with brain, breast, gastrointestinal, head and neck, and lung cancers. The history of randomized controlled trials in surgery and the structure and function of ACOSOG are discussed. ACOSOG is establishing an extensive specimen bank for current and future correlative science studies, providing unique educational opportunities for surgeons in clinical research, and pursuing collaborative relationships in order to conduct trials with private industries. Also, ACOSOG has expanded its membership to include international sites, which contribute to the success of ACOSOG studies and enhance the portfolio of future protocols. The participation of general surgeons and surgical oncologists in clinical trials is essential to the improvement of treatment options for cancer patients.

Guidelines for diagnosis and therapy of MEN type 1 and type 2

This is a consensus statement from an international group, mostly of clinical endocrinologists. MEN1 and MEN2 are hereditary cancer syndromes. The commonest tumors secrete PTH or gastrin in MEN1, and calcitonin or catecholamines in MEN2. Management strategies improved after the discoveries of their genes. MEN1 has no clear syndromic variants. Tumor monitoring in MEN1 carriers includes biochemical tests yearly and imaging tests less often. Neck surgery includes subtotal or total parathyroidectomy, parathyroid cryopreservation, and thymectomy. Proton pump inhibitors or somatostatin analogs are the main management for oversecretion of entero-pancreatic hormones, except insulin. The roles for surgery of most entero-pancreatic tumors present several controversies: exclusion of most operations on gastrinomas and indications for surgery on other tumors. Each MEN1 family probably has an inactivating MEN1 germline mutation. Testing for a germline MEN1 mutation gives useful information, but rarely mandates an intervention. The most distinctive MEN2 variants are MEN2A, MEN2B, and familial medullary thyroid cancer (MTC). They vary in aggressiveness of MTC and spectrum of disturbed organs. Mortality in MEN2 is greater from MTC than from pheochromocytoma. Thyroidectomy, during childhood if possible, is the goal in all MEN2 carriers to prevent or cure MTC. Each MEN2 index case probably has an activating germline RET mutation. RET testing has replaced calcitonin testing to diagnose the MEN2 carrier state. The specific RET codon mutation correlates with the MEN2 syndromic variant, the age of onset of MTC, and the aggressiveness of MTC; consequently, that mutation should guide major management decisions, such as whether and when to perform thyroidectomy.

Prophylactic thyroidectomy, based on direct genetic testing, in patients at risk for the multiple endocrine neoplasia type 2 syndromes

Since the discovery that germ-line mutations in the RET protooncogene are responsible for the multiple endocrine neoplasia (MEN) syndromes types 2A and 2B, prophylactic thyroidectomy has been recommended for MEN patients to prevent medullary thyroid carcinoma (MTC). In this report, we present the medium-term follow up results on the earliest group of 18 patients having prophylactic thyroidectomy for MEN 2A. There were no operative complications. Microscopic or grossly evident MTC was present in 14 (78%) of the resected patients. None of the patients had metastasis of their MTC to regional lymph nodes. At three years' follow up, there is no evidence of residual or recurrent MTC, based on biochemical testing. We conclude that prophylactic thyroidectomy, based on direct DNA testing for RET gene mutations, is an effective and safe way to manage MTC in patients with MEN 2A.

Medullary carcinoma of the thyroid gland

Medullary thyroid carcinoma (MTC) is an uncommon thyroid tumor that has attracted a great deal of interest because of its frequent presentation as a familial tumor and its primary involvement in the type II multiple endocrine neoplasia (MEN) syndromes MEN-IIA and MEN-IIB and familial medullary thyroid carcinoma (FMTC). The MTC tumor cells secrete the polypeptide hormone calcitonin, which serves as an excellent tumor marker, useful for defining the presence of disease, preoperatively or following thyroidectomy. The discovery that mutations in the RET proto-oncogene are associated with MEN-II syndromes was highly significant in that it demonstrated a clear correlation between genotype and phenotype; and most importantly it provided a mechanism whereby family members at risk could be identified by direct DNA analysis. Virtually all patients with MEN-IIA, MEN-IIB, and FMTC develop MTC; therefore there is a clear rationale for performing thyroidectomy as soon as a RET mutation has been identified. Because MTC appears to be much more aggressive in patients with MEN-IIB, thyroidectomy is performed during the first year of life in this setting, whereas in patients with MEN-IIA, where the tumor appears to be more indolent, the procedure can be safety delayed until age 5 years. Reoperative neck exploration in patients with evidence of persistent or recurrent MTC has been effective in a significant number of patients, although the success of the operation requires careful patient selection and preoperative assessment. MTC, as expressed in the MEN-II syndromes, is an excellent model to evaluate the usefulness of interventional therapy in patients demonstrated to have a genetic predisposition for cancer.

Four new mutations in the DNA mismatch repair gene MLH1 in colorectal cancers with microsatellite instability. Mutations in brief no. 157. Online

Hereditary nonpolyposis colorectal cancer (HNPCC) is frequently associated with inherited mutation in one of four DNA mismatch repair genes. Somatic mutations in the same genes are also found in a subset of sporadic colorectal cancers. A defect in DNA mismatch repair results in a RER (replication error) tumor phenotype. We screened 110 archival and 11 prospectively acquired colorectal cancers for the RER phenotype. A total of 22 cancers were RER-positive. RER-positive tumors were investigated for mutations in the DNA mismatch repair gene MLH1 using single-strand-conformation-polymorphism (SSCP) analysis. We identified four previously undescribed mutations in four different samples. Three mutations were exonic: a point mutation at codon 69 (AGG-->AAG(arg-->lys]); a single base pair deletion at codon 42/43 (GCAAAATCC-->GCAAATCC) leading to a new stop codon downstream; and a point mutation at codon 757 (TAA-->TAT [termination-->tyr] which extend the MLH1 peptide by 36 ammino acids. The fourth mutation was a 1 base pair insertion six base pairs 5' to the start of exon 14 (tttgtttt-->tttggtttt). The mutations were not seen in the patients' constitutional DNA. The somatic MLHI mutations identified appear to be causally associated with the RER phenotype.

Germline mutations in the multiple endocrine neoplasia type 1 gene: evidence for frequent splicing defects

Multiple endocrine neoplasia type 1 (MEN 1) is a familial cancer syndrome characterized by parathyroid hyperplasia, pituitary adenomas, and neuroendocrine tumors of the pancreas and duodenum. In 1997, the MEN1 tumor suppressor gene was identified, and numerous germline mutations have been reported to be distributed throughout the gene. We used single strand conformational variant (SSCV) analysis to search for germline mutations in the members of 33 kindreds with a confirmed diagnosis of MEN 1. SSCV analysis revealed 25 conformational variants representing germline mutations that are predicted to result in loss of normal menin function. Twenty different disease-associated mutations were identified: five resulting in potential abnormal RNA splicing, two missense mutations, seven nonsense mutations, and six frameshift mutations. The aberrant splice products were identified and confirmed by RT-PCR and direct sequence analysis for two of the five splice mutations. Sixteen of the 20 (80%) mutations identified have not been previously reported. Mutations were not identified in eight kindreds with signs and symptoms consistent with MEN 1. The SSCV analysis revealed mutations in 76% (25 of 33) of the kindreds investigated, thus showing SSCV analysis to be a reliable mutation detection strategy. One-fifth of the mutations identified in this study involve intron sequences, therefore, highlighting the importance of including intron sequences in the search for germline mutations in the MEN1 gene. The need to investigate the entire gene when characterizing new MEN 1 families presents challenges in the translation of genetic studies to efficient clinical diagnostic tests.

The importance of molecular biology to cancer surgery

Over the last two decades there have been striking advances in molecular biology, which now have, and will continue to have, great impact on the diagnosis and treatment of patients with either benign or malignant diseases. The translation of these new findings from the laboratory to the clinic has just begun and promises to revolutionize the care of patients with certain neoplastic diseases. The most significant advances relate to molecular genetics, particularly the identification of inherited germline mutations that can be identified in kindred members by direct DNA testing. The surgical oncologist is in a pivotal position to define prophylactic interventional strategies for patients who are destined to develop certain solid tumor malignancies. The most immediate opportunities will be in the patients with hereditary disorders, such as breast cancer, large bowel cancer, and the endocrine neoplasia syndromes.

A specific CpG methylation pattern of the MGMT promoter region associated with reduced MGMT expression in primary colorectal cancers

The enzyme O6-methylguanine-DNA methyltransferase (MGMT) protects cells from the cytotoxic and mutagenic effects of alkylating agents. Approximately 20% of tumor cell lines lack MGMT activity and are highly sensitive to alkylating agents. In established cancer cell lines, MGMT expression appears to be correlated with methylation of residues in both the promoter and the body of the gene. The effect of methylation of the MGMT promoter on gene expression and carcinogenesis in primary tumors is unknown. We investigated methylation of the MGMT promoter region in primary colorectal cancers and normal colonic mucosa. We used five methylation-sensitive restriction enzymes (BssHII, SacII, Eagl, Nael, and Smal) and Southern blot analysis to assess methylation in 46 cancers and 22 controls. Methylation of Eagl and Nael sites was seen in 12 tumors but in none of the 22 normal colorectal mucosa specimens. This difference was statistically significant (P<0.01). Methylation-sensitive single-nucleotide primer extension analysis of four additional cytosine residues confirmed methylation of the promoter region in the tumors identified by Eagl and Nael digestions and served to further quantitate the extent of methylation. Western blot analysis of 21 tumors revealed statistically significant lower MGMT expression in the eight tumors with methylation of the Eagl and Nael sites and nt -128 than in the 13 tumors lacking the methylation pattern (P<0.05). MGMT activity was lower in tumors with methylation than in tumors that were not methylated. The difference was not, however, statistically significant. We conclude that a subset of colorectal tumors is characterized by a specific methylation pattern in the MGMT promoter associated with reduced MGMT expression.

The health beliefs, values, and practices of gay adolescents

Barriers to optimal health in the gay adolescent population include a lack of recognition or acceptance by healthcare providers, homophobic attitudes, and an absence of awareness regarding the healthcare needs of this vulnerable population. The literature suggests that gay youths experience such problems as lack of self-esteem, school truancy and dropout, runaway behavior and subsequent homelessness, drug and alcohol abuse, prostitution and sexually transmitted diseases, depression, and suicide. Advanced practice nurses have the opportunity to improve the health of gay youths through recognition, education, outreach, and advocacy.

Compartment-mediated dissection for papillary thyroid cancer

There is considerable controversy surrounding the appropriate treatment of papillary thyroid carcinoma (PTC), most of which centers around the extent of thyroidectomy. Despite the advocation of less than total thyroidectomy by many surgeons, there is a renewed interest by others, mainly in Europe and Japan, in the performance of routine total thyroidectomy and extensive lymph-node dissection for PTC. This has been shown to be an effective strategy for medullary thyroid carcinoma, which is not responsive to thyroid suppression or radioactive iodine treatment. PTC, however, is well treated by these adjuvant modalities and, in general, has an excellent prognosis. The benefit of extensive operations for routine cases of PTC has not been proven, and this practice is not employed by most surgeons in the United States. Node dissection is reserved for those patients with palpable adenopathy.

A specific CpG methylation pattern of the MGMT promoter region associated with reduced MGMT expression in primary colorectal cancers

The enzyme O6-methylguanine-DNA methyltransferase (MGMT) protects cells from the cytotoxic and mutagenic effects of alkylating agents. Approximately 20% of tumor cell lines lack MGMT activity and are highly sensitive to alkylating agents. In established cancer cell lines, MGMT expression appears to be correlated with methylation of residues in both the promoter and the body of the gene. The effect of methylation of the MGMT promoter on gene expression and carcinogenesis in primary tumors is unknown. We investigated methylation of the MGMT promoter region in primary colorectal cancers and normal colonic mucosa. We used five methylation-sensitive restriction enzymes (BssHII, SacII, Eagl, Nael, and Smal) and Southern blot analysis to assess methylation in 46 cancers and 22 controls. Methylation of Eagl and Nael sites was seen in 12 tumors but in none of the 22 normal colorectal mucosa specimens. This difference was statistically significant (P<0.01). Methylation-sensitive single-nucleotide primer extension analysis of four additional cytosine residues confirmed methylation of the promoter region in the tumors identified by Eagl and Nael digestions and served to further quantitate the extent of methylation. Western blot analysis of 21 tumors revealed statistically significant lower MGMT expression in the eight tumors with methylation of the Eagl and Nael sites and nt -128 than in the 13 tumors lacking the methylation pattern (P<0.05). MGMT activity was lower in tumors with methylation than in tumors that were not methylated. The difference was not, however, statistically significant. We conclude that a subset of colorectal tumors is characterized by a specific methylation pattern in the MGMT promoter associated with reduced MGMT expression.

Lethality of multiple endocrine neoplasia type I

The lethality of the endocrine tumors associated with multiple endocrine neoplasia type I (MEN-I), particularly the pancreatic islet cell tumors, has been controversial. We evaluated the cause and age of death in MEN-I kindreds. Our database contains 34 distinct kindreds with 1838 members. Reliable death data are available for 103 people (excluding accidents and age < 18 years). We compared survival curves of MEN-I patients who died from causes related to MEN-I with those from MEN-I carriers who died from a nonendocrine cause and unaffected kindred members. We also compared ages of death between affected and unaffected members of MEN-I kindreds. Of 59 MEN-I-affected patients, 27 died directly of MEN-I-specific illness and 32 of non-MEN-I causes. The MEN-I-specific deaths occurred at a younger age (median 47 years) than either MEN-I patients whose death was from some nonendocrine cause (median 60 years, p < 0.02) or than all kindred members who did not die of MEN-I disease (median 55 years, p < 0.05). The causes of death of the MEN-I patients included islet cell tumor (n = 12), ulcer disease (n = 6), hypercalcemia/uremia (n = 3), carcinoid tumor (n = 6), and nonendocrine malignancies (n = 9). There was no difference in survival between MEN-I carriers and unaffected kindred members. Of our MEN-I patients, 46% died from causes related to their endocrine tumors after a median age of 47 years, which was younger than family members who did not die from these tumors. Pancreatic islet cell tumors were the most common cause of death of MEN-I patients. Management of kindreds with MEN-I should include an aggressive screening program with early therapeutic intervention when a tumor is identified.

Surgical management of patients with persistent or recurrent medullary thyroid cancer

Residual or recurrent medullary thyroid carcinoma (MTC), manifested by elevated calcitonin levels, occurs commonly following primary treatment of MTC. Re-operation in appropriately selected patients is the only treatment modality which consistently and reliably reduces stimulated calcitonin levels, and results in excellent local disease control. We report improved results of surgical management of recurrent MTC in two consecutive series of patients. In our most recent series (1992-96), 38% of patients (17 out of 45) had normal postoperative stimulated calcitonin levels, compared to 28% (nine of 32) in our first series (1990-92). In the most recent series, only 13% (six of 45) of patients had no decrease in calcitonin levels following re-operation, compared to 31% (10 of 32) in our first series (P = 0.07, Fisher's exact test). This improvement has mainly occurred through better preoperative selection of patients, and the institution of routine laparoscopic liver examination preoperatively, which identified metastases in 10 patients, nine of whom had normal CT or MRI imaging.

Presidential Address. Transitions

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Pancreatic polypeptide is a useful plasma marker for radiographically evident pancreatic islet cell tumors in patients with multiple endocrine neoplasia type 1

BACKGROUND

The usefulness of human pancreatic polypeptide (hPP) as a plasma marker for islet cell neoplasms is controversial. We sought to determine the relation between fasting plasma hPP levels and radiographically detectable pancreatic islet cell tumors in patients with multiple endocrine neoplasia type 1 (MEN 1).

METHODS

Fasting plasma hPP levels were measured prospectively in 202 individuals from 31 independent kindreds with MEN 1. Plasma levels greater than 3.0 times the normal age-specific values were defined as elevated. Patients with elevated plasma hPP levels were evaluated with computed tomographic scanning and magnetic resonance imaging, octreotide scanning, or selective angiography.

RESULTS

Twenty-two patients had elevated fasting plasma hPP levels, and 20 of these patients were evaluated radiographically. Pancreatic lesions were detected in 19 patients. A group of eight patients with normal basal fasting plasma hPP levels were evaluated with computed tomography, magnetic resonance imaging, octreotide scanning, or selective angiography based on clinical presentation. One patient in this group had an imaging study that was positive for a pancreatic lesion.

CONCLUSIONS

The presence of a markedly elevated fasting plasma hPP level in patients with MEN 1 is 95% sensitive and 88% specific for the presence of radiographically detectable pancreatic islet cell tumors.

Medullary carcinoma of the thyroid gland and the MEN 2 syndromes

Medullary thyroid carcinoma (MTC) is an uncommon neoplasm in children that usually is associated with the multiple endocrine neoplasia (MEN) syndrome types 2A and 2B and with familial medullary thyroid carcinoma (FMTC). Recently, germline mutations in the RET proto-oncogene have been found in patients with these syndromes. Thus, with direct DNA testing, kindred members with MEN 2A, MEN 2B, or FMTC can be identified before clinical of biochemical evidence of MTC develops. It has been hypothesized that prophylactic thyroidectomy early in childhood, based on a positive genetic test, produces a better clinical outcome than thyroidectomy at the time MTC is diagnosed either clinically or biochemically. In the present report, the Washington University experience with MTC in children with MEN 2A and 2B is reviewed. Sixteen patients with MEN 2A who had thyroidectomy based on the biochemical diagnosis of MTC are compared with 14 children with MEN 2A who underwent prophylactic thyroidectomy based on direct genetic testing. In addition, the clinical results of 11 patients with MEN 2B treated for MTC are reviewed. After 3 years of follow-up there has been no biochemical or clinical evidence of MTC among the 14 children who had prophylactic thyroidectomy. Among the 16 children with MEN 2A who had thyroidectomy because of elevated basal of stimulated calcitonin levels, four (25%) have persistent of recurrent MTC after a mean follow-up period of 7.6 years. Of the 11 patients with MEN 2B who underwent thyroidectomy during childhood, one has died and seven (70%) of the remaining patients have recurrent MTC after a mean follow-up period of 11 years. The authors conclude that a significant number of children with MEN 2A or MEN 2B, who have clinical of biochemical evidence of MTC before thyroidectomy, have persistent or recurrent disease after long-term clinical follow-up. The diagnosis by direct DNA testing in patients with these syndromes allows prophylactic thyroidectomy before the development of extensive local or metastatic MTC.

"Cold" single-strand conformational variants for mutation analysis of the RET protooncogene

BACKGROUND

RET protooncogene mutation analysis is a routinely performed predictive DNA test in kindreds affected by multiple endocrine neoplasia (MEN) types 2A and 2B and familial medullary thyroid carcinoma (FMTC), and is a valuable diagnostic tool in newly diagnosed cases of medullary thyroid carcinoma (MTC).

METHODS

We tested the suitability of the recently introduced "cold" single-strand conformational variant (SSCV) technique, which promises rapid, simple, nonradioactive detection of sequence variants in the identification of germline and somatic RET mutations. A total of 11 different mutations in exon 10 (codons 609, 611, 618, and 620) and 6 mutations in exon 11 (codon 634) were studied.

RESULTS

Conditions were optimized so that conformational variants were demonstrated for all mutations examined in a single setting for exons 10 and 11. A novel six base pair (bp) inframe deletion between cysteines 630 and 634 was detected in a sporadic MTC. This adds to the evidence that not only cysteine deletions and substitutions but also changes in the spacing between cysteine residues have a pathogenic effect.

CONCLUSIONS

Our results indicate that the cold SSCV method offers the advantages of simplicity, time savings, and nonradioactive detection for screening for RET sequence variants in hereditary and sporadic MTCs.

Novel germline RET proto-oncogene mutations associated with medullary thyroid carcinoma (MTC): mutation analysis in Japanese patients with MTC

Germ-like and somatic mutations in the RET proto-oncogene are associated with inherited and sporadic medullary thyroid carcinoma (MTC). The majority of patients with multiple endocrine neoplasia type 2A (MEN2A) and familial medullary thyroid carcinoma (FMTC) carry germ-line point mutations that result in the substitution of one of five cysteine residues. We investigated exons 10, 11, 13, 14 and 16 of the RET proto-oncogene in 33 unrelated Japanese patients with MTC. Eleven of the 33 cases (33%) were found to have germ-line mutations. Three previously unreported mutations in exon 10 and 11 were identified: one in codon 620, (TGC-->GGC), resulting in a cysteine to glycine substitution, and two in codon 630, (TGC-->TCC) and (TGC-->TAC), resulting in cysteine to serine and cysteine to tyrosine changes, respectively. The new mutations were present in the germ-line DNA of four unrelated patients for whom a family history of MTC had not been documented. Because the new RET alleles described here involve cysteine residues in a region of protein previously associated with FMTC and MEN2A, it is very likely that they represent mutations that predispose to the development of MTC.

Allelotype of follicular thyroid carcinomas reveals genetic instability consistent with frequent nondisjunctional chromosomal loss

Numerous studies aimed at the identification of chromosomal regions that are frequently deleted in specific tumor types have pointed to the location and involvement of specific tumor suppressor genes. Previous studies of loss of heterozygosity (LOH) among thyroid tumors have revealed frequent allelic deletions at a few chromosomal regions. A systematic genome-wide examination of LOH in a substantial number of follicular carcinomas, however, has not been performed previously. We assessed LOH at polymorphic markers from each nonacrocentric autosomal arm in a panel of 28 follicular thyroid carcinoma tumor and normal pairs. In contrast to the results of previous allelotype studies, we found high rates of LOH at multiple chromosomal regions. The highest rate of loss in our study was at 2p (50.0%), and 2q (50.0%), and the mean rate of LOH was 20.4%. Marked genetic instability in a subset of tumors was demonstrated by high fractional allelic loss, which accounted for more than 80% of observed LOH in this study. High fractional allelic loss was significantly associated with oxyphilic features and poor differentiation of these tumors. Our data provide evidence of a prevalent phenotype of nondisjunctional whole chromosomal loss in follicular thyroid carcinomas.

Differential display in primary and metastatic medullary thyroid carcinoma

Despite recent advances in the understanding of the role of the RET proto-oncogene in the development of familial and approximately 30% of sporadic medullary thyroid carcinomas (MTC), little is known about other genetic events that modify the course and outcome of the disease. We compared the expression of genes in intrathyroidal MTCs to autologous local lymph node metastases by means of mRNA differential display (DDRT-PCR). This is the first report of differential display using surgical specimens of a primary cancer and its metastases. Total RNA was extracted from tumor tissue of two patients with MTC associated with multiple endocrine neoplasia (MEN 2B) and sporadic MTC, respectively. Following reverse transcription (RT), the products were PCR-amplified and separated on a denaturating polyacrylamide gel. RT-PCR products demonstrating differential expression were reamplified and used as probes for Northern blot analysis. Six fragments for which differential expression was confirmed were cloned and sequenced. Resultant sequences were tested for homology to sequences in public data bases, and two novel MTC-derived fragments (MDF-1, MDF-2) were identified. Sensitivity of the method was confirmed by identification of a sequence encoding the calcitonin precursor flanking peptide which is expressed almost exclusively in MTC and normal thyroid C cells. Overexpression of the ribosomal genes S3a and P0 was found in the metastases. Recent reports suggest that components of the translational apparatus act as regulatory mediators of growth, proliferation, and neoplastic change. The altered expression of ribosomal proteins and gene products encoded by MDF-1 or MDF-2 may play an important role in the progression and metastatic spread of MTC.

Parathyroid glands and the multiple endocrine neoplasia syndromes and familial hypocalciuric hypercalcemia

Hypercalcemia is a variable feature of inherited endocrine disorders. In the multiple endocrine neoplasia (MEN) syndromes, generalized hyperparathyroidism is a common feature. It occurs much more frequently in patients with MEN type 1 as compared to patients with MEN type 2A. Unlike the MEN syndromes, patients with familial hypocalciuric hypercalcemia (FHH) have only hypercalcemia with no associated endocrinopathies. The hyperparathyroidism in patients with either of the MEN syndromes is managed by parathyroidectomy, whereas patients with FHH are managed nonoperatively. The specific genetic defects associated with MEN type 2 syndromes and FHH have been identified. They explain, in part, the clinical and pathophysiologic features of these diseases. The genetic defect causative of MEN type 1 will doubtless soon be found and thereby provide further insights into the molecular basis of calcium homeostasis. We will review the clinical presentation and the management of patients with these disorders. We will also review the recent molecular discoveries in MEN 2A, MEN 2B, and FHH, and define how they have altered the management of patients who have these syndromes.

Heterotopic autotransplantation of parathyroid tissue in children undergoing total thyroidectomy

AIM

The purpose of this study was to examine the efficacy of parathyroid autotransplantation in children undergoing total thyroidectomy.

METHODS

We have prospectively evaluated 32 cases of total thyroidectomy in children. The ages ranged from 1 year to 15.7 years, and the mean was 8.9 years. In 31 cases, the indication for surgery was a diagnosis of MEN2A or 2B based on direct DNA testing. One child had suspected sporadic medullary thyroid carcinoma. All of the patients underwent heterotopic autotransplantation of parathyroid gland tissue. In 26 cases, the parathyroid tissue was placed in the nondominant forearm, while in 6 children it was autotransplanted into the sternocleidomastoid muscle.

RESULTS

In 31 of 32 children (97%), the serum calcium level transiently decreased in the immediate postoperative period. All of the patients were placed on oral calcium carbonate and vitamin D supplementation, and the serum calcium levels became normal within several days. The supplemental medications were then weaned as tolerated. Within 3 months of their procedure, 30 patients (94%) had adequate parathyroid tissue engraftment, and the calcium and vitamin D medications were discontinued. One child required 9 months of calcium and vitamin D medications before she could be weaned from the medications. One child has been treated more recently, and is currently being weaned from supplemental calcium and vitamin D. Serum PTH levels in 22 patients who had placement of the tissue into their forearms were measured, and in each there was increased PTH in the grafted arm compared with the nongrafted arm. In five children who had parathyroid tissue grafted into the sternocleidomastoid muscle, the peripheral serum PTH levels were in the normal range.

CONCLUSION

The heterotopic autotransplantation of resected parathyroid tissue is safe and effective in preventing permanent hypoparathyroidism.

Mutations in MLH1 are more frequent than in MSH2 in sporadic colorectal cancers with microsatellite instability

The microsatellite instability that is a feature of tumors in patients with hereditary nonpolyposis colorectal cancer (HNPCC) is a consequence of defective DNA mismatch repair. Mutations in the DNA mismatch repair genes MSH2 and MLH1 may account for up to 90% of HNPCC kindreds. Microsatellite instability is also seen in 10-16% of sporadic colorectal cancers. A limited number of MSH2 and MLH1 mutations have been described for sporadic colorectal cancers. In this study, we screened 12 primary sporadic colorectal cancers with microsatellite instability for mutations in MSH2 and MLH1 by using reverse transcription-polymerase chain reaction (RT-PCR) and single-strand-conformation-variant (SSCV) analysis. Eight mutations were identified in six tumors. One mutation in MLH1 was found to be present in the patient's germline DNA. Four tumors had somatic mutations in MLH1, and, in two of these tumors, two different mutations were identified. A single tumor had a somatic MSH2 mutation. Our observations suggest that MLH1 is mutated more frequently than MSH2 in sporadic colorectal cancers with microsatellite instability.

Surgical management of hyperparathyroidism in patients with multiple endocrine neoplasia type 2A

BACKGROUND

The surgical management of hyperparathyroidism in patients with multiple endocrine neoplasia type 2A (MEN 2A) is controversial. We report the long-term follow-up, mutational analysis, and surgical outcome in a large group of patients with MEN 2A and hyperparathyroidism.

METHODS

Clinical and genetic data for MEN 2A patients with biochemically and pathologically confirmed hyperparathyroidism and a minimum of 5 years of follow-up were analyzed retrospectively, and outcomes after surgical management were compared.

RESULTS

Thirty-five (29%) of 119 patients from 14 MEN 2A kindreds had biochemical and pathologic evidence of hyperparathyroidism, with a mean follow-up of 14.7 years. The phenotypic expression of hyperparathyroidism was associated with germline mutations of the RET protooncogene at codons 634 and 618. At initial operation, 21 (62%) patients had a selective resection, eight (24%) had a subtotal resection, five (14%) had total parathyroidectomy with autotransplantation, and one had an inadvertent total parathyroidectomy. Twenty-seven (77%) patients were cured by the first operation. Persistent hyperparathyroidism occurred in three (8.6%) patients, and recurrent hyperparathyroidism occurred in five (14.3%) patients; both occurred only in patients treated with selective or subtotal resection. Permanent postoperative hypoparathyroidism occurred in six (21%) of 29 patients after selective or subtotal resection, in the one patient with inadvertent total parathyroidectomy, and in one (20%) of 5 patients treated with total parathyroidectomy and autotransplantation.

CONCLUSIONS

Recurrent or persistent hyperparathyroidism occurs after selective or subtotal parathyroidectomy, as a result of either missed glands or interval development of neoplasia in previously normal parathyroid glands left in situ. Therefore we advocate total parathyroidectomy and heterotopic autotransplantation for patients with hyperparathyroidism and MEN 2A.

Parathyroid adenomas in the aortopulmonary window

PURPOSE

To describe localization studies in nine patients with ectopic parathyroid adenomas in the aortopulmonary window.

MATERIALS AND METHODS

Nine patients with ectopic parathyroid tissue (eight adenomas, one hyperplastic gland) in the aortopulmonary window were examined with ultrasound (US), computed tomography (CT), magnetic resonance (MR) imaging, and scintigraphy. Diagnostic arteriography (n = 4) and venous sampling (n = 3) were performed in the first four patients; arteriography for the purpose of staining was attempted in the last five patients.

RESULTS

The results of CT and MR imaging studies were positive in eight of nine patients (89%) and five of eight patients (63%), respectively. The results of thallium/technetium scintigraphy were negative in three patients scanned (0%), but the results of a repeat study in one patient were positive (33%). Sestamibi scans were positive in six of six patients (100%). Single photon emission CT was performed in all six patients and enabled distinction between adenomas in the aortopulmonary window and those in the thymus.

CONCLUSION

Ectopic parathyroid glands in the aortopulmonary window are usually detected at sestamibi scintigraphy, and SPECT is helpful in distinguishing these adenomas from more common adenomas in the anterior mediastinum. CT and MR imaging studies can also enable this distinction, but imaging must extend below the aortic arch.

Genetic testing and early thyroidectomy for inherited medullary thyroid carcinoma

The recent identification of mutations in the RET proto-oncogene that are associated with multiple endocrine neoplasia type 2 (MEN 2) syndromes has allowed therapeutic intervention in affected individuals on the basis of direct genetic testing. The principal endocrine neoplasm that occurs in patients with the MEN 2 syndromes is medullary thyroid carcinoma. This thyroid neoplasm is the only consistently malignant feature of the MEN 2 syndromes and it is the most common cause of death in affected patients. Kindred members at risk for one of the MEN 2 syndromes can be studied by direct DNA analysis to determine whether they have inherited a RET mutation. Those with a positive test can be treated by early thyroidectomy and cured when the disease is microscopic and localized to the thyroid gland. Total thyroidectomy is performed as early as 5 years of age and is associated with minimal morbidity and virtually no mortality. Residual or persistent medullary thyroid carcinoma following thyroidectomy can best be determined by detecting increased levels of calcitonin following the administration of intravenous calcium gluconate and pentagastrin.

The surgical scientist

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Parathyroid autotransplantation during thyroidectomy. Results of long-term follow-up

SUMMARY BACKGROUND DATA

Permanent hypoparathyroidism is a recognized complication of thyroidectomy. Operative strategies to prevent this complication include preservation of parathyroid glands in situ and autotransplantation of parathyroid glands resected or devascularized during thyroidectomy.

METHODS

An analysis of 194 patients having thyroidectomy and simultaneous parathyroid autotransplantation at Barnes Hospital from 1990 to 1994 was performed. Data were collected regarding patient demographics, indication for thyroidectomy, operative procedure, pathologic diagnoses, and postoperative course, including biochemical assessment of parathyroid autograft function.

RESULTS

Of 194 patients having either total, subtotal, or completion thyroidectomy, 104 (54%) experienced a [Ca(+2)]nadir less than or equal to 8.0 mg/dL and had symptoms and signs of hypocalcemia. Parathyroid autotransplantation was successful in 103 (99%) of these 104 cases and resulted in a 1.0% incidence of hypoparathyroidism in this series.

CONCLUSIONS

Although preservation of parathyroid glands in situ is desirable, routine parathyroid autotransplantation during thyroidectomy virtually eliminates postoperative hypoparathyroidism. Normal parathyroid glands resected or devascularized during thyroidectomy for well-differentiated thyroid carcinoma or benign disease should be transplanted in the sternocleidomastoid muscle. Patients with Multiple Endocrine Neoplasia type 2A should have parathyroid glands resected at the time of thyroidectomy for medullary thyroid carcinoma and transplanted in the nondominant forearm. Postoperative management in most patients after thyroidectomy and parathyroid autotransplantation involves temporary calcium and vitamin D replacement and close biochemical evaluation. This precautionary measure of parathyroid autotransplantation markedly reduces the incidence of permanent postoperative hypoparathyroidism.

Mxi1 tumor suppressor gene is not mutated in primary pancreatic adenocarcinoma

Amplification of the c-myc oncogene occurs in a variety of solid tumors, including pancreatic adenocarcinomas. The MXI1 gene, located at 10q24-q25, may serve to negatively regulate c-myc oncogene activity, and potentially has tumor suppressor function. As such, altered MXI1 function might contribute to tumorigenesis. We examined 40 primary human pancreatic adenocarcinomas for MXI1 mutations. Single-strand conformation variant analysis and direct sequencing of the variants revealed a MXI1 polymorphism in 1 of 40 tumors. No MXI1 mutations were identified. Southern blot analyses did not reveal any gross rearrangements of MXI1. These results suggest that MXI1 is unlikely to play a role in human pancreatic adenocarcinoma tumorigenesis.

Infrequent CDKN2 mutation in human differentiated thyroid cancers

We examined the frequency of cyclin-dependent kinase (CDK) N2 alterations in differentiated and anaplastic thyroid cancers to assess the involvement of CDKN2 in the development of these cancers. The CDKN2 gene, which encodes the cell-cycle regulator p16, was recently shown to be mutated or deleted in many tumor cell lines. Its role in the genesis of primary tumors is uncertain, however. Tumor and corresponding normal DNAs were prepared by microdissection of paraffin-embedded tissue blocks or from frozen surgical specimens of 15 papillary, 15 follicular, and five anaplastic thyroid carcinomas. The entire CDKN2 coding region was screened by single-strand conformational variant analysis and direct sequencing of variants. The presence of homozygous deletions was evaluated by multiplex polymerase chain reaction (PCR) analysis. Loss of heterozygosity (LOH) in the CDKN2 region was assessed by using flanking polymorphic markers. Two somatic missense mutations were found among the 35 thyroid cancers, one in a follicular tumor and one in an anaplastic tumor. Multiplex PCR suggested the presence of homozygous deletion in one anaplastic tumor and hemizygous deletions in four tumors. LOH studies revealed loss of 9p sequences in four follicular (27%) and two anaplastic (50%) cancers. Our data suggest that alterations in CDKN2 played a role in a minority of thyroid cancers (three of 35). LOH in the region of CDKN2 is seen in a significant proportion of follicular and anaplastic but not papillary cancers. Loss of 9p sequences suggests a role for a tumor suppressor gene in the development of follicular and anaplastic thyroid cancers.

Medullary thyroid carcinoma in children with multiple endocrine neoplasia types 2A and 2B

Recently it has become possible to identify persons who have multiple endocrine neoplasia (MEN) syndrome types 2A and 2B based on the presence of missense mutations in the RET protooncogene. Kindred members who have inherited these syndromes can be identified before clinical or biochemical evidence of medullary thyroid carcinoma (MTC) develops, the malignancy that occurs in all affected patients. It is not known whether prophylactic removal of the thyroid gland early in childhood, based on a positive genetic test result, has a better clinical outcome than that associated with thyroidectomy after MTC is diagnosed clinically or biochemically. The authors' goal was to determine the long-term outcome for patients with MEN 2A and 2B who had thyroidectomy for MTC during childhood. These results were compared with those of patients who had prophylactic removal of the thyroid gland after the genetic diagnosis of MEN 2A was established. The hospital records of 49 children with MEN 2A or 2B were reviewed. Each patient had thyroidectomy for MTC before 16 years of age. The mean age at the time of operation was 10 years, and the mean follow-up period for those who had surgery before the availability of direct DNA genetic testing was 9.8 years. The indications for surgery included an elevated basal or stimulated plasma calcitonin level, a positive genetic test result, a thyroid mass, family history of MTC, or a phenotype diagnostic of MEN 2B. All children for whom the diagnosis of MEN 2A was established by direct genetic testing had thyroidectomy within the last 2 years. Of the 11 patients with MEN 2B who underwent thyroidectomy during childhood, 10 had MTC, and only 3 (27%) remain free of disease after the mean follow-up period of 11 years. One patient died, and seven are alive with persistent MTC. Among the 24 patients with MEN 2A who had their thyroid glands removed because of a family history of MTC or because of biochemical evidence of the disease, 5 (21%) have persistent or recurrent MTC after the mean follow-up period of 9.3 years. In four of these, the MTC was confined to the thyroid gland at the time of thyroidectomy. Of the 14 children who had thyroidectomy based on direct DNA testing, MTC was present in 11. Only four had elevated levels of stimulated plasma calcitonin before surgery. None had lymph node metastasis or surgical complications. The authors conclude that a significant number of patients with MEN 2A or 2B who undergo thyroidectomy in childhood for MTC have persistent or recurrent disease long-term. The genetic diagnosis of patients with these syndromes may allow for prophylactic surgery before the development of biochemical or clinical evidence of MTC. This approach is safe, but longer clinical follow-up will be necessary to confirm that MTC has been cured.

Progression of postoperative residual medullary thyroid carcinoma as monitored by plasma calcitonin levels

BACKGROUND

Patients operated on for medullary thyroid carcinoma (MTC) frequently have persistent elevated plasma calcitonin concentrations after operation, indicating remaining tumor. The plasma calcitonin concentration in a patient with MTC roughly reflects the endogenous tumor burden. The only effective treatment for MTC is surgical. The decision about whether a patient with persistent MTC should have a repeat operation would be influenced by knowledge of the natural course of the disease.

METHODS

Forty patients with persistently elevated peak plasma calcitonin concentrations after thyroidectomy for MTC were monitored for a mean of 6 years. Serial determinations of plasma calcitonin levels were obtained before and after intravenous injection of calcium and pentagastrin.

RESULTS

At the first postoperative test 63% of the patients had undetectable basal calcitonin values, although their stimulated plasma calcitonin concentrations were elevated. The mean annual increase in stimulated plasma calcitonin concentrations was 117%, but plasma calcitonin concentrations were stable in three patients and decreased in one patient. Five patients are known to have experienced distant metastases.

CONCLUSIONS

MTC is a progressive disease in most patients with persistent hypercalcitoninemia after thyroidectomy. Stimulated peak plasma calcitonin levels are more meaningful than basal levels in the serial postoperative evaluation of patients with persistent hypercalcitoninemia after thyroidectomy for MTC.

Creating a culturally competent workforce

Culturally sensitive health care professionals will have a distinct advantage in the 21st century. As the United States continues to grow as a multicultural society, practitioners will require access to cultural diversity training tailored to the needs of health care providers. The American Occupational Therapy Association offers an array of such educational resources through its Multicultural Affairs Program.

Frequent mutations of CDKN2 in primary pancreatic adenocarcinomas

The gene encoding the cell-cycle regulatory protein p16, CDKN2, is localized on chromosome band 9p21. CDKN2 is frequently deleted or mutated in a variety of tumor cell lines, including pancreatic cancer cell lines and xenografts, as well as in some primary tumors. We examined 32 primary pancreatic adenocarcinomas for CDKN2 mutations and for loss of heterozygosity of 9p21 sequences to assess the role of CDKN2 in pancreatic carcinogenesis. Single-strand conformation variant analysis (SSCV) and direct sequencing of the variants revealed somatic CDKN2 mutations in 11 of 32 tumors (five frame-shift mutations, five nonsense mutations, and one missense mutation). One tumor appeared to be characterized by homozygous deletion of CDKN2. These results suggest that CDKN2 plays an important role during tumorigenesis or tumor progression in a significant proportion of pancreatic adenocarcinomas.

RET gene and its implications for cancer

The RET proto-oncogene encodes a protein receptor tyrosine kinase. RET mutations are associated with the dominantly inherited cancer syndromes multiple endocrine neoplasia (MEN) types 2A and 2B and familial medullary thyroid carcinoma (FMTC). In MEN 2A, MEN 2B, and FMTC, direct detection of RET mutations can be used to identify disease allele carriers prior to the development of clinically evident neoplasms. RET mutations are also associated with sporadic thyroid carcinomas. The effects of RET mutation on protein function have been investigated both in vivo and in vitro, and the study of RET has served to provide insights into the mechanisms of tumorigenesis in general.

Mapping eight new polymorphisms in 11q13 in the vicinity of multiple endocrine neoplasia type 1: identification of a new distal recombinant

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant disorder that predisposes affected individuals to neoplasms of the parathyroid glands, endocrine pancreas, anterior pituitary, and carcinoids. The MEN1 locus has been localized by family studies to 11q13, flanked by markers PGA and D11S97. Eight new polymorphisms located in three separate radiation-reduced somatic cell hybrid segregation groups were developed. The order of the new markers, within the context of previously described loci, was determined by linkage analysis on the Venezuelan reference pedigree. Four independent MEN1 families, consisting of 57 affected individuals, and 70 individuals at-risk for the disease were genotyped. Sixteen people inherited a chromosome that shows recombination between a linked marker and the disease. The nearest proximal and distal markers that show recombination with the disease are D11S822 and GSTP1, respectively, thereby narrowing the candidate region for MEN1 by 50% on the distal side. Using these loci in haplotype analysis, an accurate presymptomatic molecular diagnostic test has been developed. These new markers in 11q13 linked to MEN1 also facilitate the genetic and physical characterization of this very gene-rich region.