Succinate Dehydrogenase Complex: An Updated Review.

Succinate dehydrogenase (SDH) is uniquely tasked with a dual role in the essential energy-producing processes of a cell. Although SDH subunits and assembly factors form part of the same enzyme complex, mutations in their respective genes lead to significantly different clinical phenotypes. Remarkable discoveries in the last 17 years have led to the delineation of the SDH complex deficiency syndrome and its multiple pathogenic branches. Here we provide an updated overview of SDH deficiency in order to raise awareness of its multiple connotations including nonneoplastic associations and pertinent features of the continually growing list of SDH-mutant tumors so as to better direct genetic counseling and predict prognosis.

Encapsulated follicular variant of papillary thyroid carcinoma/noninvasive follicular thyroid neoplasm with papillary-like nuclear features with Spindle Cell Metaplasia: Case report and review of literature.

Spindle cell lesions of the thyroid are rare overall, and span a wide clinical spectrum that ranges from spindle cell metaplasia (SCM1) to anaplastic carcinoma. Their differentiation is only seldom straightforward, and usually requires the integration of the clinical, histological and immunohistochemical data. Only a handful of publications have described cases of SCM in the thyroid and we add to that literature by reporting a unique case of encapsulated follicular variant of papillary thyroid carcinoma/noninvasive follicular thyroid neoplasm with papillary-like nuclear features with SCM. In addition, we review the literature on the relationship between SCM and different thyroid lesions, summarizing the morphological and immunohistochemical features that aid in its differentiation from more aggressive spindle cell proliferations.

Fine-needle aspiration diagnosis of primary hydatid disease of the thyroid; first reported case in the USA.

Echinococcosis or hydatid disease (HD) is a parasitic disease caused by species of the Echinococcus genus. Since the incidence of HD in the USA is very low and the primary HD of the thyroid is extremely rare even in endemic regions, the occurrence of primary thyroid HD is exceptional in the USA. Thyroid HD is rarely diagnosed by fine-needle aspiration (FNA). Our literature review revealed less than ten cases of primary HD of thyroid diagnosed by FNA worldwide. Hereby, we report the first case of a primary thyroid HD diagnosed by fine-needle aspiration in the USA.

Renal Angiomyolipoma With Sarcoid Granulomas: Report of a Unique Case.

Angiomyolipoma is a mesenchymal neoplasm characterized by the coexpression of melanocytic and smooth muscle markers. Sarcoidosis is a multisystem disorder of unknown etiology, which presents with characteristic nonnecrotizing granulomas and rarely involves the kidney. The coexistence of renal sarcoidosis with renal neoplasms is exceedingly rare and was reported only with renal cell carcinoma. Renal sarcoidosis associated with a nonepithelial renal neoplasm, such as an angiomyolipoma has never been reported. We present the first reported case of sarcoid granulomas in a renal angiomyolipoma, including morphologic and immunohistochemical features.

Tracheal Diverticulum: A Unique Case with Intraoperative Morphologic Assessment.

There are rare case reports of tracheal diverticula or paratracheal air cysts. These cases, however, were reported mostly as incidental sonographic or radiologic findings without histologic confirmation. Furthermore, the handful of studies that describe this entity histopathologically report only cases in patients with prior respiratory symptoms. Here, we report a rare case of an asymptomatic 60-year-old female with no significant past medical history who presented with primary hyperparathyroidism. She was found to have an incidental right paraesophageal air-filled diverticulum with multiple thin septations on her imaging studies. She was taken to surgery and the histologic examination of the specimen revealed multiloculated cystic cavity lined by respiratory-type columnar epithelium with lymphocytic infiltrate and minor salivary glands within the surrounding stroma, rendering the diagnosis of tracheal diverticula.

Schwannoma including epithelial elements mimicking pleomorphic adenoma of the submandibular gland on fine-needle cytology: The first case report.

Although most salivary gland tumors can be diagnosed accurately on fine-needle aspiration, cytological evaluation of spindle cell lesions, including schwannomas, still poses a challenge. In salivary gland aspirates, the most important mimickers of schwannomas are the common pleomorphic adenomas/mixed tumors since these may yield abundant spindle-shaped myoepithelial cells and only scant epithelial cells. Therefore, in spindle cell-rich aspirates from the head and neck, diligent search for epithelial cells is recommended. Their presence traditionally favors pleomorphic adenoma and argues against a schwannoma. Herein, however, we report, for the first time, a schwannoma with epithelial elements (glandular schwannoma) in the submandibular gland, demonstrating that the presence of epithelial cells in a spindle cell-rich aspirate may not always exclude a schwannoma.

Long-term adaptation of the human lung tumor cell line A549 to increasing concentrations of hydrogen peroxide.

Previously, we demonstrated that A549, a human lung cancer cell line, could be adapted to the free radical nitric oxide (NO●). NO● is known to be over expressed in human tumors. The original cell line, A549 (parent), and the newly adapted A549-HNO (which has a more aggressive phenotype) serve as a useful model system to study the biology of NO●. To see if tumor cells can similarly be adapted to any free radical with the same outcome, herein we successfully adapted A549 cells to high levels of hydrogen peroxide (HHP). A549-HHP, the resulting cell line, was more resistant and grew better then the parent cell line, and showed the following characteristics: (1) resistance to hydrogen peroxide, (2) resistance to NO●, (3) growth with and without hydrogen peroxide, and (4) resistance to doxorubicin. Gene chip analysis was used to determine the global gene expression changes between A549-parent and A549-HHP and revealed significant changes in the expression of over 1,700 genes. This gene profile was markedly different from that obtained from the A549-HNO cell line. The mitochondrial DNA content of the A549-HHP line determined by quantitative PCR favored a change for a more anaerobic metabolic profile. Our findings suggest that any free radical can induce resistance to other free radicals; this is especially important given that radiation therapy and many chemotherapeutic agents exert their effect via free radicals. Utilizing this model system to better understand the role of free radicals in tumor biology will help to develop new therapeutic approaches to treat lung cancer.

Part I. Development of a model system for studying nitric oxide in tumors: high nitric oxide-adapted head and neck squamous cell carcinoma cell lines.

The free radical nitric oxide (NO) is over-expressed in many tumors, including head and neck squamous cell carcinomas (HNSCC); however, the role NO plays in tumor pathophysiology is still not well understood. We, herein, report the development of an in vitro model system which can be used to probe the role of NO in the carcinogenesis of HNSCC. Five HNSCC cell lines were adapted to a high NO (HNO) environment by gradually introducing increasing concentrations of DETA-NONOate, a nitrogen-based NO donor, to cell media. The adaptation process was carried out until a sufficiently high enough donor concentration was reached which enabled the HNO cells to survive and grow, but which was lethal to the original, unadapted ("parent") cells. The adapted HNO cells exhibited analogous morphology to the parent cells, but grew better than their corresponding parent cells in normal media, on soft agar, and in the presence of hydrogen peroxide, an oxygen-based free radical donor. These results indicate that the HNO cell lines are unique and possess biologically different properties than the parent cell lines from which they originated. The HNO/parent cell lines developed herein may be used as a model system to better understand the role NO plays in HNSCC carcinogenesis.

Part II. Initial molecular and cellular characterization of high nitric oxide-adapted human tongue squamous cell carcinoma cell lines.

It is not understood why some head and neck squamous cell carcinomas, despite having identical morphology, demonstrate different tumor aggressiveness, including radioresistance. High levels of the free radical nitric oxide (NO) and increased expression of the NO-producing enzyme nitric oxide synthase (NOS) have been implicated in tumor progression. We previously adapted three human tongue cancer cell lines to high NO (HNO) levels by gradually exposing them to increasing concentrations of an NO donor; the HNO cells grew faster than their corresponding untreated ("parent") cells, despite being morphologically identical. Herein we initially characterize the HNO cells and compare the biological properties of the HNO and parent cells. HNO/parent cell line pairs were analyzed for cell cycle distribution, DNA damage, X-ray and ultraviolet radiation response, and expression of key cellular enzymes, including NOS, p53, glutathione S-transferase-pi (GST-pi), apurinic/apyrimidinic endonuclease-1 (APE1), and checkpoint kinases (Chk1, Chk2). While some of these properties were cell line-specific, the HNO cells typically exhibited properties associated with a more aggressive behavior profile than the parent cells (greater S-phase percentage, radioresistance, and elevated expression of GST-pi/APE1/Chk1/Chk2). To correlate these findings with conditions in primary tumors, we examined the NOS, GST-pi, and APE1 expression in human tongue squamous cell carcinomas. A majority of the clinical samples exhibited elevated expression levels of these enzymes. Together, the results herein suggest cancer cells exposed to HNO levels can develop resistance to free radicals by upregulating protective mechanisms, such as GST-pi and APE1. These upregulated defense mechanisms may contribute to their aggressive expression profile.

Long-term adaptation of breast tumor cell lines to high concentrations of nitric oxide.

Nitric oxide (NO), a free radical, has been implicated in the biology of human cancers, including breast cancer, yet it is still unclear how NO affects tumor development and propagation. We herein gradually adapted four human breast adenocarcinoma cell lines (BT-20, Hs578T, T-47D, and MCF-7) to increasing concentrations of the NO donor DETA-NONOate up to 600 muM. The resulting model system consisted of a set of fully adapted high nitric oxide ("HNO") cell lines that are biologically different from the "parent" cell lines from which they originated. Although each of the four parent and HNO cell lines had identical morphologic appearance, the HNO cells grew faster than their corresponding parent cells and were resistant to both nitrogen- and oxygen-based free radicals. These cell lines serve as a novel tool to study the role of NO in breast cancer progression and potentially can be used to predict the therapeutic response leading to more efficient therapeutic regimens.

Gastroesophageal reflux disease (GERD): is there more to the story?

Gastroesophageal reflux disease (GERD) affects both men and women worldwide, with the most common symptom of GERD being frequent heartburn. If left untreated, more serious diseases including esophagitis and/or esophageal cancer may result. GERD has been commonly held to be the result of gastric acid refluxing into the esophagus. Recent work, however, has shown that there are acid-producing cells in the upper aerodigestive tract. In addition, acid-producing bacteria located within the upper gastrointestinal tract and oral cavity may also be a contributing factor in the onset of GERD. Proton pump inhibitors (PPIs) are commonly prescribed for treating GERD; these drugs are designed to stop the production of gastric acid by shutting down the H(+)/K(+)-ATPase enzyme located in parietal cells. PPI treatment is systemic and therefore significantly different than traditional antacids. Although a popular treatment choice, PPIs exhibit substantial interpatient variability and commonly fail to provide a complete cure to the disease. Recent studies have shown that H(+)/K(+)-ATPases are expressed in tissues outside the stomach, and the effects of PPIs in these nongastric tissues have not been fully explored. Likewise, acid-producing bacteria containing proton pumps are present in both the oral cavity and esophagus, and PPI use may also adversely affect these bacteria. The use of PPI therapy is further complicated by the two philosophical approaches to treating this disease: to treat only symptoms or to treat continuously. The latter approach frequently results in unwanted side effects which may be due to the PPIs acting on nongastric tissues or the microbes which colonize the upper aerodigestive tract.

Human lung mucous glands manifest evidence of the H+/K+-ATPase proton pump.

OBJECTIVES: The H+/K+-ATPase proton pump has been demonstrated in human laryngeal submucosal glands, and is not solely present in the parietal cells of the stomach. Although proton secretion is present in the lung, a variety of mechanisms have been elucidated. The hypothesis of this study is that the H+/K+-ATPase proton pump is one additional pathway of proton secretion in the human lung. METHODS: Fourteen surgical lung specimens from 10 subjects were retrospectively obtained after approval from our Human Subjects Committee. Banked human stomach tissue was used for comparative positive and negative controls. Sections were immunostained with 2 monoclonal antibodies selectively reactive with alpha or beta subunits of the H+/K+-ATPase proton pump. RESULTS: In the human lung, consistent staining for both subunits was present in the mucous gland cells and ducts in all specimens in which mucous glands were present (6 specimens from 5 subjects). Overall, weak to strong staining was present in focal areas within the multicellular mucous glands. There was only scant focal staining in the respiratory epithelium in 4 specimens. Stomach parietal cells exhibited strongly positive staining for both subunits of the proton pump. There was no staining in stomach cells that were not morphologically consistent with parietal cells. CONCLUSIONS: The H+/K+-ATPase proton pump is present in mucous cells and ducts in the human lung, with some variable expression noted. Proton pump inhibitor pharmacotherapy may have a site of action in the human lung, explaining some of the controversies otherwise attributable to interrelatedness of aerodigestive tract disease.

Significance of extensive hyperkeratosis on cervical/vaginal smears.

OBJECTIVE: To assess the significance of reporting hyperkeratosis on cervical/vaginal (CV) smears. STUDY DESIGN: Cases diagnosed with extensive hyperkeratosis (E-HK) and without prior or concurrent history of neoplasia, squamous intraepithelial lesion or atypical squamous cells of undetermined significance (ASCUS) were retrieved from our files for the period January 1994-August 2001. E-HK is defined in our practice as patches of anucleated squames with irregular, angulated edges present in at least 5 low-power (10 x eyepiece and 10 x objective) fields on a conventional CV smear. On liquid-based preparations, we use 3 low-power fields. Only cases with a follow-up CV smear and/or cervical biopsy (CB) were selected. RESULTS: Among 328 cases of E-HK, 138 patients met the study selection criteria. Eighty-one cases had negative CV smears and/or CB, 17 (12.3%) patients had persistent E-HK, and a subsequent diagnosis of ASCUS or higher was made in 40 patients (28.9%). Among the 40 cases with subsequent abnormalities, 13 (9.4%) were diagnosed with ASCUS, 24 (17.4%) with HPV or dysplasia, and 3 (2.1%) with malignancy. CONCLUSION: While isolated, anucleate squames may have no clinical importance in patient management, E-HK can be a significant marker of underlying neoplastic disease. This should be kept in mind as one decides how to report CV cytology based on 2001 Bethesda System recommendations.