Severe Obesity Associated with Pituitary Corticotroph Hyperplasia and Neoplasia:

OBJECTIVE

Obesity is associated with hypercortisolism. The incidence of corticotroph hyperplasia or lymphocyte infiltration in the pituitary of patients with obesity is unknown.

METHODS

Pituitary and adrenal glands from 161 adult autopsies performed between 2010 and 2019 at our institution were reviewed. Clinical history, body mass index, and cause of death were recorded Routine hematoxylin & eosin, reticulin and immunohistochemical stains for ACTH, CD3, and CD20 were done. Results were analyzed using Fisher and Chi-square statistics.Decedents were separated into 4 groups based on BMI (kg/m²): Lean (BMI <25.0), Overweight (BMI of 25.0 to 29.9), Obesity Class I (BMI of 30.0 to 34.9), and Obesity Class II-III (BMI > 34.9).

RESULTS

Corticotroph hyperplasia/neoplasia was identified in 44 of 161 pituitary glands. 4 of 53 (9.1%) lean patients had pituitary lesions whereas 27.3% (12) of overweight, 22.7% (10) of obesity class I and 40.9% (18) of obesity class II patients had hyperplasia (p < 0.0001). Small corticotroph tumors were identified in 15 patients; only one was a lean patient and the tumor was associated with Crooke's hyaline change of nontumorous corticotrophs. The presence of corticotroph hyperplasia and neoplasia was associated with adrenal cortical hyperplasia and lipid depletion. Microscopic foci of T lymphocytes and B lymphocytes were identified in pituitaries of patients within each weight category; no independent association between BMI and lymphocytic inflammation was found.

CONCLUSION

Our data indicate an association between corticotroph hyperplasia/neoplasia and obesity. It remains unclear whether obesity is the cause or effect of ACTH and cortisol excess.

Molecular Profiling of Pediatric and Adult Glioblastoma

OBJECTIVES

Although glioblastoma (GBM) is rare in the pediatric population, it is the most common cause of death among children with central nervous system neoplasms. Recent molecular profiling of these neoplasms has demonstrated distinct differences in comparison to their adult counterparts. Moreover, many pediatric GBMs occur within the context of cancer predisposition syndromes, such as constitutional mismatch repair deficiency syndrome (CMMRD). Children with CMMRD who develop GBM exhibit a high tumor mutational burden and may benefit from treatment with immune checkpoint inhibitors.

METHODS

We performed next-generation sequencing and immunohistochemistry for mismatch repair proteins in our cohort of pediatric and adult GBMs to further characterize the molecular profiles of these groups.

RESULTS

We examined a total of 11 pediatric and 11 adult GBMs. Pediatric patients had a higher number of alterations compared to their adult counterparts. They also had a higher frequency of alterations in the mismatch repair genes, which can be detected by immunohistochemistry (IHC). We also identified one pediatric patient with CMMRD syndrome.

CONCLUSIONS

Our study highlighted the distinct molecular differences between pediatric and adult GBM. We also demonstrated that pediatric patients have a higher frequency of alterations in the mismatch repair genes, which may render them susceptible to treatment with immune checkpoint inhibitors. These alterations can be detected using routine IHC and should be performed on all pediatric GBM.

Adult Diffuse Astrocytic and Oligodendroglial Tumors

Infiltrating gliomas comprise the most common group of primary intraparenchymal brain tumors and present a level of complexity which requires careful integration of histopathology and molecular diagnostics for optimal therapy. To this end, the fourth edition of the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) has been followed by a series of publications by cIMPACT-NOW (the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy) incorporating molecular signatures to propose updated diagnostic categories in anticipation of the upcoming fifth edition of CNS tumor classification. Integration of histopathology, immunophenotyping, and molecular findings is profoundly changing the practice of diagnostic surgical neuropathology and enabling a more personalized approach to treating patients with gliomas.

Proteins inform survival-based differences in patients with glioblastoma

BACKGROUND

Improving the care of patients with glioblastoma (GB) requires accurate and reliable predictors of patient prognosis. Unfortunately, while protein markers are an effective readout of cellular function, proteomics has been underutilized in GB prognostic marker discovery.

METHODS

For this study, GB patients were prospectively recruited and proteomics discovery using liquid chromatography-mass spectrometry analysis (LC-MS/MS) was performed for 27 patients including 13 short-term survivors (STS) (≤10 months) and 14 long-term survivors (LTS) (≥18 months).

RESULTS

Proteomics discovery identified 11 941 peptides in 2495 unique proteins, with 469 proteins exhibiting significant dysregulation when comparing STS to LTS. We verified the differential abundance of 67 out of these 469 proteins in a small previously published independent dataset. Proteins involved in axon guidance were upregulated in STS compared to LTS, while those involved in p53 signaling were upregulated in LTS. We also assessed the correlation between LS MS/MS data with RNAseq data from the same discovery patients and found a low correlation between protein abundance and mRNA expression. Finally, using LC-MS/MS on a set of 18 samples from 6 patients, we quantified the intratumoral heterogeneity of more than 2256 proteins in the multisample dataset.

CONCLUSIONS

These proteomic datasets and noted protein variations present a beneficial resource for better predicting patient outcome and investigating potential therapeutic targets.

Acceptable Weight Ranges for Research Tissue Procurement and Biorepositories, 2015-2017

Background: The Cooperative Human Tissue Network, Midwestern Division, is a National Cancer Institute-funded program that provides quality research biospecimens to qualified investigators. Consented human tissues are procured according to researcher specifications for weight (size) and preservation type; weights of samples in significant demand and limited supply are negotiated. Weights of procured tissues are entered into a dedicated biospecimen database. This study seeks to provide guidance for acceptable tissue weights for researchers.

Methods: Tissue weights by year and anatomic site were retrieved from the database for primary malignant tissues. The total number of tissues included was 5141. Statistical evaluation of data included the number of tissues for each year, anatomic site as well as minimum, maximum, average weights, standard deviation, and standard error. Anatomic sites with few tissues were excluded.

Results: “Stock price” type graphs were constructed to show an average as “volume” with both full weight ranges and range that accommodated 80% of tissues. Average weight and number of sample trends varied by anatomic site. Tissues fell into four weight groups; 10 and 90 percentile boundaries were calculated for each. Smallest average research tissue weights for middle 80% were recorded for prostate and oropharynx (140 mg). Second weight group included tonsil, thyroid, breast, oral cavity, larynx, pancreas, salivary gland, skin, tongue, lung, and parotid (265 mg). The third group included stomach, cervix, colon, esophagus, endometrium, bone, brain, bladder, small bowel, uterus, liver, kidney lymph node, adrenal, and ovary (513 mg). The fourth and heaviest weight group included soft tissue tumors and spleen (1201 mg).

Conclusions: Since tissue weights are not usually included in recommendations for research tissue procurement or for frozen tissues stored in biorepositories, we offer this data as a practical guide to researcher acceptable tissue weights for selected sites based on a 3-year researcher request and acceptance history.

Histologically Proven Radiation-Induced Brainstem Glioma 93 Months After External Beam Radiotherapy for Pituitary Macroadenoma: Radiation Treatment Dose and Volume Correlation

Patient is a 29-year-old with a history of recurrent growth hormone-secreting pituitary macroadenoma diagnosed 12 years prior to presentation. Eight years prior to current presentation, the patient underwent re-resection and received 50.4 Gy external beam radiotherapy (EBRT) in 28 fractions of 1.8 Gy each. Serial postradiation MRIs demonstrated regression in pituitary tumor size. Patient presented with new headaches 7.5 years after completing EBRT. Brain MRI demonstrated new FLAIR hyperintensity and contrast enhancement within the pons and medulla, corresponding to the 36 Gy isodose line of each radiation dose fraction. Differential diagnosis included radiation necrosis and radiation-induced glioma (RIG). The patient's neurologic exam worsened over the following 4 months. MRI showed progressive increase in mass effect, extent of FLAIR hyperintensity, and contrast enhancement in the brainstem. Stereotactic-assisted biopsy showed infiltrating astrocytoma with moderate atypia. A PubMed search showed this is the first case of histologically verified brainstem RIG correlated with 3-dimensional conformational radiation therapy dose and volume planning following EBRT for a pituitary adenoma. The rare occurrence of brainstem RIG after radiation therapy for pituitary tumor supports the need for long-term imaging monitoring of such patients.

Differences in mitochondrial function and antioxidant systems between regions of human glioma

Metabolic features and oxidative stress have been extensively studied in cancer cells. However, comparative studies between cancer cell populations that coexist in human neoplastic tissue are not frequently available. The aim of the present study was to characterize markers of oxidative status and mitochondrial function in center vs. periphery of human fresh glioma samples; therefore, antioxidant systems, oxidative stress and mitochondrial parameters were assessed in gross total resections of gliomas. Mitochondrial protein and mitochondrial DNA content, enzymatic activities of mitochondrial oxidative and phosphorylative system, antioxidant mechanisms, mitochondrial H(2)O(2) production, oxygen consumption and cellular oxidative damage were measured in human gliomas. Concentric regions of human glioma tissue showed similar mitochondrial structural markers; conversely, the functionality of their isolated mitochondria was significantly different. In this way, the tumor periphery exhibited higher respiratory rate and fewer antioxidant systems than tumor center. Our results have expanded previous investigations, which report the presence of cell populations with different oxidative susceptibility in human brain tumor samples. This is, to our knowledge, the first study to investigate metabolic differences in concentric regions of gross total resections of glioma. Interestingly, the cancer cell population that exhibits an increased antioxidant capacity within the tumor mass might be responsible for tumor resistance to chemotherapy and radiotherapy.

Critical assessment of the current guidelines for the management and treatment of morbidly obese patients

An interdisciplinary panel of specialists met in Mallorca in the first European Symposium on Morbid Obesity entitled; "Morbid Obesity, an Interdisciplinary Approach". During the two and half days of the meeting, the participants discussed several aspects related to pathogenesis, evaluation, and treatment of morbid obesity. The expert panel included basic research scientists, dietitians and nutritionists, exercise physiologists, endocrinologists, psychiatrists, cardiologists, pneumonologists, anesthesiologists, and bariatric surgeons with expertise in the different weight loss surgeries. The symposium was sponsored by the Balearic Islands Health Department; however, this statement is an independent report of the panel and is not a policy statement of any of the sponsors or endorsers of the Symposium. The prevalence of morbid obesity, the most severe state of the disease, has become epidemic. The current recommendations for the therapy of the morbidly obese comes as a result of a National Institutes of Health (NIH) Consensus Conference held in 1991 and subsequently reviewed in 2004 by the American Society for Bariatric Surgery. This document reviews the work-up evaluation of the morbidly obese patient, the current status of the indications for bariatric surgery and which type of procedure should be recommended; it also brings up for discussion some important real-life clinical practice issues, which should be taken into consideration when evaluating and treating morbidly obese patients. Finally, it also goes through current scientific evidence supporting the potential effectiveness of medical therapy as treatment of patients with morbid obesity.

Is ghrelin the culprit for weight loss after gastric bypass surgery? A negative answer

BACKGROUND

Ghrelin is a potent appetite stimulator, mainly synthesized in the stomach. Paradoxically, obese subjects have lower plasma ghrelin than lean subjects and increase their weight in spite of low ghrelin levels. The role of ghrelin in weight regulation after bariatric surgery is still controversial. The aim of this study was to evaluate whether rapid weight loss after laparoscopic Roux-en-Y gastric bypass surgery (LRYGBP), was associated with changes in plasma ghrelin levels. In addition, we determined the acute impact of LRYGBP on insulin resistance and adiponectin levels.

METHODS

49 morbidly obese subjects who underwent LRYGBP were studied. 19 subjects who underwent other laparoscopic gastrointestinal surgeries acted as the control group. Fasting plasma levels of ghrelin, insulin and adiponectin were determined preoperatively and 2 hours, 10 days and 6 months postoperatively.

RESULTS

At 2 hours after LRYGBP, there was a significant reduction in ghrelin and adiponectin levels, which coincided with elevated plasma glucose and insulin levels. Interestingly, once glucose and insulin levels normalized at 6 months after surgery, ghrelin also normalized. Adiponectin reached pre-surgical levels at 10 days after LRYGBP and continued to significantly rise until 6 months postoperatively.

CONCLUSION

Weight loss after LRYGBP occurs in spite of the absence of significant changes in plasma ghrelin levels. Improvement of insulin resistance occurred within 10 days after surgery, and could be related to the normalization of adiponectin levels. This data questions the role of peripheral ghrelin as a cause of weight loss in obese humans after LRYGBP.

Leptin increases proliferation of human steosarcoma cells through activation of PI(3)-K and MAPK pathways

BACKGROUND

Serum leptin levels are strongly and directly related to fat body mass (FBM). Bone mineral density (BMD) increases with FBM, and obesity has a protective effect against osteoporosis. We have previously demonstrated that leptin therapy has a significant effect in preventing ovariectomy-induced bone loss in rats and leptin also exerts direct osteogenic effects in vitro. To obtain a better understanding of the physiology and pharmacology of leptin in bone metabolism, we evaluated the leptin-induced signal transduction pathways and proliferative response in the human osteosarcoma cell line Saos-2.

MATERIAL/METHODS

Saos-2 cell lines were used. Leptin receptor common form (OB-Ra) and long form (OB-Rb) were detected by RT-PCR and immunocytochemistry. PI(3)-K activity was immunoprecipitated using antibodies directed against tyrosine-phosphorylated proteins and IRS-1. The activated form of p42/p44 MAPK was investigated in cytosolic extracts of confluent Saos-2 in response to leptin.

RESULTS

In this study, we tested the hypothesis that leptin might be a mediator linking obesity and bone cell proliferation. We found that Saos-2 cells expressed OB-Ra and OB-Rb. Leptin (10 nmol/L - 2 umol/L) caused a significant increase in the activation of PI (3)-K that was accompanied by an increase in cell proliferation dose dependently based on the [3H]-thymidine incorporation. The specific PI (3)-K inhibitors LY294002 and wortmannin blocked leptin-induced cell proliferation. Interestingly, leptin activated MAPK and the specific MAPK-inhibitor PD98059 blocked DNA synthesis induced by leptin.

CONCLUSIONS

Our data support the hypothesis that leptin may increase bone mass by stimulating osteoblast proliferation through activation of the P1 (3)-K and MAPK signaling pathways.

Potential role of hypothalamic ghrelin in the pathogenesis of human obesity

Ghrelin is a potent appetite stimulator, mainly synthesized in the stomach but also made in the brain. Paradoxically, obese subjects have lower plasma ghrelin than lean subjects and increase their weight in spite of low ghrelin levels. We hypothesize that central, and not peripheral ghrelin, is primarily responsible for overeating in humans. The aim of this study was to determine hypothalamic ghrelin levels in lean vs obese subjects. We collected anterior hypothalamus from lean and obese patients at the time of autopsy, and Western blots and semiquantitative RT-PCR for ghrelin and neuropeptide Y (NPY) were carried out. Our results showed that ghrelin expression was significantly higher in the hypothalamus of obese subjects compared to lean ones. This finding correlates with similar increases in NPY in the obese group. Ghrelin and NPY mRNA levels followed the same trend and were significantly higher in the hypothalamus in obese compared to lean subjects, suggesting a central origin for the increased protein content in the obese subjects. In conclusion, obesity in humans is associated with elevated central ghrelin. This data questions the significance of the role of peripheral ghrelin in the regulation of appetite in humans and suggests an important role for central ghrelin in the pathogenesis of obesity in humans.

Microdissection genotyping of gliomas: therapeutic and prognostic considerations

Molecular anatomic pathology represents the blend of traditional morphological methods and the multigene approach to determine cancer-related gene alterations for diagnostic and prognostic purposes. Microdissection genotyping was utilized to characterize 197 gliomas with targeted microdissection of 2-7 areas spanning the spectrum of histologic types and grades. The methodology described herein is complementary to the existing realities of pathology practice. The technique utilizes paraffin-embedded fixative-treated tissue of small sample size after the primary morphological examination by the pathologist. Molecular information derived from microdissection genotyping in combination with the traditional histological information, results in an enhanced understanding of glioma formation and biological progression leading to improvements in diagnosis and prediction of prognosis. In all, 100% or 32 of 32 cases with at least partial treatment response was observed in neoplasms possessing the 1p or 1p/19q loss. The 19q loss alone without coexisting 1p showed no improvement in treatment response. Gliomas lacking 1p loss with only allelic loss involving 3p, 5q, 9p, 10q and 17p showed unfavorable outcome of only 35%, or six of 17 cases with treatment response. In addition, the determination of fractional allelic loss (favorable/unfavorable), was a very good independent predictor of biological behavior. These findings emphasize the importance of determining the cumulative pattern of mutational damage on 16 distinct sites or more, especially in the presence of 1p loss which in isolation or in combination with 19q is a favorable prognostic factor for therapeutic response.

Gliosarcoma with epithelial differentiation: immunohistochemical and molecular characterization. A case report and review of the literature

Few reported cases of gliosarcomas or glioblastomas with epithelial-like areas exist. Most cases were originally diagnosed as metastatic carcinoma. Focal expression of glial fibrillary acidic protein has helped characterize these tumors as having a glial origin. We report a case of gliosarcoma with multifocal, extensive areas of well-differentiated carcinoma; demonstrating squamous and glandular differentiation. The expression of glial fibrillary acidic protein and epithelial phenotype were mutually exclusive. We performed extensive immunohistochemical analyses and comparative genotypic analysis using microdissection to secure representative glial and epithelial components. Loss of heterozygosity was analyzed with a panel of 12 polymorphic microsatellite markers designed to indicate allelic loss and situated in proximity to known tumor suppressor genes located on chromosomes 1p, 9p, 10q, 17p and 19q. We found comparable patterns of acquired allelic loss between the glial and carcinomatous components, strongly supporting the monoclonal origin of this neoplasm. This case represents an extreme form of phenotypic divergence in a malignant glioma, and constitutes a difficult diagnostic challenge. This heterogeneity reflects the potential for a range of phenotypic expression in malignant gliomas that needs to be recognized. We suggest microdissection genotyping as a molecular technique to better characterize these tumors.

Leptin access into the brain: a saturated transport mechanism in obesity

In spite of extensive research in the last few years, we still do not have a clear understanding of how does leptin access its targets in the brain, and whether there is postreceptor defect in the brain of obese individuals. Recent data have shown that leptin is produced in the pituitary, where its receptor is also present. A better understanding of how leptin reaches the brain and how it modulates the release of hypothalamic neuropeptides and pituitary hormones is needed. This information is crucial in order to better understand the role that leptin may play in the pathophysiology of diseases, such as obesity, delayed puberty, or growth defects.

Leptin and leptin receptor in anterior pituitary function

Leptin is a 16 kDa protein that exerts important effects on the regulation of food intake and energy expenditure by interacting with the leptin receptor in the brain and in many other tissues. Although leptin is produced mainly by white adipose tissue, several laboratories have shown low levels of leptin production by a growing number of tissues including the anterior pituitary gland. Many studies have implicated leptin in anterior pituitary function including the observation that homozygous mutations of the leptin receptor gene led to morbid obesity, lack of pubertal development and decreased GH and TSH secretion. In addition, leptin functions as a neuroendocrine hormone and regulates many metabolic activities. Leptin also interacts with and regulates the hypothalamic-pituitary-adrenal, the hypothalamic-pituitary-thyroid and the hypothalamic-pituitary-gonadal axes. All of the anterior pituitary cell types express the leptin receptor. However, leptin has been localized in specific subtypes of anterior pituitary cells indicating cell type-specific production of leptin in the anterior pituitary. Subcellular localization of leptin indicates co-storage with secretory granules and implicates hypothalamic releasing hormones in leptin secretion from anterior pituitary hormone cells. Leptin signal transduction in the anterior pituitary has been shown to involve the janus protein-tyrosine kinase (JAK)/signal transducer and activation of transcription (STAT) as well as suppressor of cytokine signalling (SOCS). These proteins are activated by tyrosine-phosphorylation in anterior pituitary cells. The various steps in pituitary leptin signal transduction remain to be elucidated.

Limited brain access for leptin in obesity

Obesity is a major health problem that contributes to the development of type 2 diabetes, hypertension, dyslipidemia, and cardiovascular disease. The current pharmacological therapies for obesity are limited and may have significant side effects. Leptin therapy was shown to effectively cause weight loss in obese rats, however its effectiveness in humans is still under investigation. Obese humans have significantly elevated plasma leptin concentrations compared with lean individuals. Plasma leptin concentrations strongly correlated with percentage of body fat. Leptin concentration in the cerebrospinal fluid (CSF) is correlated, in a nonlinear manner, with plasma leptin levels and body mass index (BMI). The ratio of CSF leptin levels to serum leptin levels was 4 times greater in lean individuals than in obese individuals. One interpretation of this finding is that human obesity could be secondary to a central resistance to leptin action, causing a relative leptin deficiency in the CNS. Six years after the discovery of leptin we still do not have a clear understanding of how leptin accesses its targets in the brain, or whether there is defect in this process in the brain of obese individuals. In this manuscript we will review the different leptin gateways to the brain and the potential sites where a defect in leptin action may be present, as well as some potential clinical implications of leptin. A better understanding of how leptin reaches the brain and how it modulates the release of hypothalamic neuropeptides will be important in understanding the role that leptin plays in the pathophysiology of obesity.

Ductal carcinoma in situ diagnosed with stereotactic core needle biopsy: can invasion be predicted?

PURPOSE

To determine whether mammographic or histologic features can be used to predict which cases diagnosed as ductal carcinoma in situ (DCIS) without invasion by means of stereotactic core needle biopsy (SCNB) will have invasive disease at surgery.

MATERIALS AND METHODS

From July 1992 to March 1999, DCIS without invasion was diagnosed by means of SCNB in 59 patients. Seventeen (29%) were found to have invasive disease after surgery. The underestimation rate for SCNB was compared with that obtained by means of open surgical biopsy. Mammographic and histologic features of cases with and those without invasion were compared.

RESULTS

All patients had calcifications on mammograms. There was no significant difference (P: =.26) between the underestimation rate for SCNB with the 11-gauge vacuum-assisted device and that for open surgical biopsy. No statistically significant differences between cases with and those without invasion were seen in patient age, mean number of core specimens, level of suspicion, size of lesion, distribution and morphology of the calcifications, presence of an associated mass or density, subtype of DCIS, nuclear grade, or presence of necrosis or desmoplasia.

CONCLUSION

Mammographic and histologic features cannot be used reliably to predict cases that are underestimated with SCNB. However, SCNB with the 11-gauge vacuum-assisted device was as reliable as open surgical biopsy for diagnosing DCIS without invasion.

Chordoid meningioma: a clinicopathologic study of 42 cases

The term chordoid meningiomas was first used by Kepes et al. in 1987 to describe a meningeal tumor in young patients associated with microcytic anemia and/of dysgammaglobulinemia. Such tumors were composed of spindle or epithelioid cells disposed in chordoma-like clusters and cords in a myxoid matrix and often featured a prominent lymphoplasmacellular infiltrate. Our study includes 42 chordoid meningiomas that represented 0.5% of all meningiomas operated at Mayo Clinic during the interval 1975 to 1997. The male to female ratio was 1:1 and the age range was 12 to 77 years (mean, 47.4 yrs). Only two (5.2%) occurred in children. The majority (88%) were large and supratentorial. No manifestation of systemic disease was noted. Chordoid elements comprised 10% to 100% of the tumors: 34 (81%) were more than 50% chordoid. Thirty-seven tumors (88%) were classified as typical and five as atypical. Lymphoplasmacytic infiltrates varied, being moderate in 10 cases (23.8%), mild in 15 (35.7%), and absent in 17 (40.5%). In 14 (42%) of the 33 cases with available follow up, one or more recurrences were noted. All but one recurrent tumor had been subtotally resected. In 86% of recurrent tumors, the primary lesion was more than 50% chordoid in pattern and contained little or no inflammatory infiltrate. In our experience, chordoid meningiomas are primarily tumors of adults, lack sex predilection, are unassociated with systemic manifestations, and uniformly recur when subtotally excised.

Obesity is associated with a decreased leptin transport across the blood-brain barrier in rats

Leptin exerts important effects on the regulation of food intake and energy expenditure by acting in the brain. Leptin is secreted by adipocytes into the bloodstream and must gain access to specific regions in the brain involved in regulating energy balance. Its action is mediated by interaction with a receptor that is mainly expressed in the hypothalamus but is also present in other cerebral areas. To reach these target areas, leptin most likely needs to cross the blood-brain barrier (BBB). In this study, we compared the permeability of leptin at the BBB in homozygous lean (FA/FA), high-fat diet-induced (HFD) obese rats (FA/FA rats on a highfat diet), and genetically obese fa/fa Zucker rats by quantifying the permeability coefficient surface area (PS) product after correction for the residual plasma volume (Vp) occupied by leptin in the vessel bed of different brain regions. The intravenous bolus injection technique was used in the cannulated brachial vein and artery using leptin radioiodinated with 2 isotopes of iodine (125I and 131I) to separately determine the PS and Vp values. The PS for leptin at the BBB in lean FA/FA rats ranged from 11.0 +/- 1.6 at the cortex to 14.8 +/- 1.4 x 10(-6) ml x g(-1) x ml(-1) at the posterior hypothalamus. The PS for leptin in HFD obese FA/FA and obese fa/fa rats ranged from 3.0- to 4.0-fold lower than in lean FA/FA rats. The Vp values were not significantly different among the 3 groups studied. SDS-PAGE analysis of the radioiodinated leptin after 60 min of uptake revealed intact protein in the 8 different brain regions. Plasma leptin levels were significantly higher in both obese rat groups compared with those in lean FA/FA rats. Leptin levels in cerebrospinal fluid were not significantly different among the 3 groups of rats. These findings strongly suggest that the leptin receptor (OB-R) in the BBB can be easily saturated. Saturation of the BBB OB-R in obese individuals would explain the defect in leptin transport into the brain described in this study.

The long form of the leptin receptor (OB-Rb) is widely expressed in the human brain

Leptin exerts important effects on the regulation of food intake and energy expenditure by acting in the brain. Leptin action is mediated by the interaction with a receptor that is alternatively spliced, resulting in at least five different isoforms. The long form (OB-Rb) has a long intracellular domain that is essential for intracellular signal transduction. The specific aim of this study was to further investigate the role that the brain may play in the pathogenesis of obesity in humans. We studied the expression of OB-R mRNA (both short or common and long isoforms) in the brains of obese, lean and diabetic subjects, by in situ hybridization, semiquantitative RT-PCR and Northern blots analysis. We used two alternative probes: one that recognizes all known splice variants (OB-Ra) and a second that recognizes only the long form, OB-Rb. Several brain regions, including hypothalamus, cerebellum, neocortex, entorrhinal cortex, amygdala, and rostral medulla, were evaluated. In situ hybridization studies revealed that both OB-Ra and OB-Rb mRNAs are widely distributed in the human brain. The specific hybridization signal with both probes was detected exclusively in the cytoplasm of the cell body, dendrites and proximal axons of neurons. Hypothalamic nuclei, Purkinje cells and dentate nuclei of the cerebellum, inferior olivary and cranial nerves nuclei in the medulla, amygdala and neurons from both neocortex and entorrhinal cortex demonstrated positive signals. The hybridization signal obtained in ependyma was lower than that in neurons and no specific hybridization was detected in glial cells. No significant differences were identified among the regions or among the three groups studied. These results match those previously obtained by us [Couce et al.: Neuroendocrinology 1997;66:145] in which the distribution of the OB-R protein in the human brain was first described. RT-PCR indicated that the OB-Rb was highly expressed in the hypothalamus and cerebellum. No significant differences of OB-Ra or OB-Rb mRNA expression were identified in lean or obese individuals in these two cerebral regions. The levels of OB-Rb were significantly higher in cerebellum compared to hypothalamus in lean and obese individuals. The original hypothesis that OB-Rb is present only in the hypothalamus needs to be reconsidered. This OB-Rb isoform seems to be widely expressed in the human brain with highest levels in the cerebellum. Obesity and hyperleptinemia appears not to be associated with down-regulation of the OB-Rb in the human brain.

Leptin and leptin receptor expression in rat and mouse pituitary cells

Leptin is a circulating hormone secreted mainly by adipose tissue. Recent studies have shown leptin production by other tissues, including the placenta, stomach, and mammary tissues. Various reports have suggested that the anterior pituitary may have a role in the regulatory effects of leptin. We recently localized leptin in the human anterior pituitary, but analysis of leptin in rodent pituitary has not been previously reported. In this study we examined rat and mouse pituitary tissues and various cell lines for leptin by RT-PCR, immunohistochemistry, and Western blotting. Leptin receptor messenger RNA was also examined in these tissues by RT-PCR. Leptin was present in a small percentage of rat (4.8 +/- 0.7%) and mouse (7 +/- 2%) pituitary cells. Colocalization studies with leptin and pituitary hormones showed leptin expression mainly in TSH cells (24 +/- 2% of TSH cells in the rat pituitary and 31 +/- 1% of TSH cells in the mouse pituitary). A folliculo-stellate (FS) cell line, TtT/GF, also expressed leptin. The long isoform of leptin receptor (OB-Rb) was present in normal pituitary and in various pituitary cell lines, including FS, GH3, and alphaT3-1 cells. Treatment of GH3 and FS cells with leptin (1 x 10(-8) M) inhibited cell proliferation assessed by [3H]thymidine incorporation in GH3, but not in FS, cells. These findings show for the first time that leptin is expressed in rat and mouse anterior pituitaries mainly by TSH cells and by a mouse FS cell line. The finding of leptin and of the long isoform of leptin receptor in normal rat and mouse pituitaries and in various cell lines implicates an autocrine/paracrine loop in the production and regulation of leptin and leptin receptor in the rodent pituitary.

Fibrous meningioma with tyrosine-rich crystals

A 58-year-old African-American woman presented with a 6-month history of headaches. A magnetic resonance imaging scan of the head revealed a 5-cm, enhancing dura-based mass in the left parietal region. The variably cellular tumor was composed of uniform spindle cells associated with intercellular collagen and numerous radially arranged "petal-shaped" clusters of eosinophilic crystals. The tumor was diagnosed by light microscopy as a fibrous meningioma. Ultrastructural examination disclosed cells with complex interdigitating processes connected by desmosome-like cell junctions, abundant intercellular collagen fibers, and prominent, densely osmiophilic crystals featuring radiating teardrop shaped petals emanating from a central core. A positive Millon reaction showed these crystals to consist at least in part of tyrosine. By morphology, histochemistry, and ultrastructure, the crystals resembled tyrosine-rich crystals occurring in salivary gland tumors. This is the first report of a fibrous meningioma containing tyrosine-rich crystals.

Leptin and leptin receptor expression in normal and neoplastic human pituitary: evidence of a regulatory role for leptin on pituitary cell proliferation

Leptin is a circulating hormone secreted by adipose and a few other tissues. The leptin receptor consists of a single transmembrane-spanning polypeptide that is present as a long physiologically important form as well as in several short isoforms. Recent studies have suggested that the anterior pituitary may have a role in the regulatory effects of leptin in animal models. To test this possibility in human pituitaries, we examined the expression of leptin and OB-R in normal and neoplastic pituitaries, and the possible functions of leptin in the pituitary were also analyzed. Leptin was present in 20-25% of anterior pituitary cells and was expressed in most normal anterior pituitary cells, including ACTH (70% of ACTH cells), GH (21%), FSH (33%), LH (29%), TSH (32%), and folliculo-stellate cells (64%), but was colocalized with very few PRL cells (3%), as detected by double labeling immunohistochemistry with two different antileptin antibodies. In addition, leptin expression was detected by RT-PCR in some pituitary tumors, including ACTH (three of four), GH (one of four), null cells (two of four), and gonadotroph (one of four) tumors as well as in normal pituitary. Immunohistochemical staining showed greater immunoreactivity for leptin in normal pituitaries compared to adenomas. Treatment of an immortalized cultured anterior pituitary cell line, HP75, with leptin stimulated pancreastatin secretion in vitro. Leptin also inhibited cell growth in the human HP75 and in the rat pituitary GH3 cell lines. Both long (OB-Rb) and common (OB-Ra) forms of the leptin receptor messenger ribonucleic acid and leptin receptor protein were expressed in normal and neoplastic anterior pituitary cells. These findings show for the first time that leptin is expressed by most human anterior pituitary cell types and that there is decreased leptin protein immunoreactivity in pituitary adenomas compared to that in normal pituitary tissues. We also show that OB-Rb is widely expressed by normal and neoplastic anterior pituitary cells, implicating an autocrine/paracrine loop in the production and regulation of leptin in the pituitary.

Analysis of K-ras, N-ras, H-ras, and p53 in lung neuroendocrine neoplasms

This study screened 11 samples of typical carcinoid (TC), 4 samples of atypical carcinoid (AC), 1 sample of large cell neuroendocrine carcinoma (LCNEC), and four metastases for point mutations in exons 5 to 8 of the p53 gene, and exons 1 and 2 of the K-ras. H-ras, and N-ras genes using polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) and direct sequencing and by immunohistochemistry for p53. Exon 1 of K-ras was mutated in two samples of low-grade AC and a metastasis from one of these tumors (GAT12 and AGT12, respectively). No mutations in N-ras or H-ras were found. Mutations in exons 5 and 8 of the p53 gene were identified in a high-grade AC and a LCNEC. Positive immunostaining for p53 was present in three samples, with only one genotypic mutation shown (LCNEC). In conclusion, point mutations of the p53 gene were infrequent in these pulmonary neuroendocrine tumors, did not correlate in all samples with immunostaining, and were associated with the higher-grade tumors. Second, the presence of K-ras mutations seems to be associated with the higher-grade carcinomas. Third, N-ras and H-ras mutations were not found with these pulmonary neuroendocrine tumors.

From slowly progressive amnesic syndrome to rapidly progressive Alzheimer disease

A 57-year-old woman had a neuropsychologically documented 5-year history of a slowly progressive amnesic syndrome followed by a 1-year history of rapidly progressive dementia. There was no family history of dementia. Magnetic resonance imaging failed to show a structural basis, electroencephalography failed to show changes of Creutzfeldt-Jakob disease, and cerebrospinal fluid examination was normal. A diagnosis of Alzheimer disease was confirmed by brain biopsy. The abrupt change in disease course was unique but suggested probable overlap between posited subtypes of Alzheimer disease.

Localization of leptin receptor in the human brain

Leptin (OB protein), the product of the adipose-specific ob gene, exerts important effects in the regulation of food intake and energy expenditure. Based upon results from animal studies, several groups have suggested that this action may be exerted in the brain, specifically in the hypothalamic region. However, to date, the localization of the OB-R in the human brain has not been described. One aim of this study was to contribute to a better understanding of the role that the central nervous system plays in the pathogenesis of obesity in humans. A first stage was to determine the OB-R expression in the human brain by means of immunohistochemistry and Western blotting. Several brain regions from 17 lean, 14 obese, and 4 diabetic (NIDDM) subjects, obtained from archival autopsy material, were sampled. Brain samples from neocortex, hypothalamus, medualla, limbic system, pineal and cerebellum were routinely processed in paraffin and analyzed with the avidin-biotin immunoperoxidase and diaminobenzidine detection method. Western blotting (WB) analysis was done on fresh brain tissue from an obese patient. Specific OB-R immunoreactivity was localized in the choroid plexus epithelium, ependymal lining, and neurons of the hypothalamic nuclei (arcuate, suprachiasmatic, mamillary, paraventricular, dorsomedial, supraoptic and posterior), nucleus basalis of Meynert, inferior olivary nuclei and cerebellar Purkinje cells. No differences in OB-R immunoreactivity were found among the three groups examined. WB analysis yielded 97- and 125-kD bands in the hypothalamus and cerebellum. In summary, this paper presents the first evidence to indicate the specific localization of the OB-R in the brain of lean, obese and NIDDM subjects.

Expression of insulin-like growth factor-II (IGF-II) and IGF-II/mannose-6-phosphate receptor in the rat hippocampus: an in situ hybridization and immunocytochemical study

After 3 or 4 weeks of age, insulin-like growth factor-II (IGF-II) gene expression in normal rats has been detected only in mesenchymal tissue associated with the central nervous system. In contrast, the IGF-II/mannose-6-phosphate receptor has been reported to be widely distributed in adult rat brain. This study was performed in order to clarify the cellular localization of IGF-II and IGF-II/mannose-6-phosphate receptor in rat brain by comparing an immunocytochemical map with the distribution of mRNAs by in situ hybridization. The highest levels of IGF-II mRNA were detected in the choroid plexus and meningeal membranes. In contrast, IGF-II receptor transcripts were mainly present in neuron-rich areas such as the hippocampus, with a lower signal present in the choroid plexus and meninges. Specific IGF-II receptor immunoreactivity was present in neurons throughout the forebrain, with the highest intensity in the pyramidal cell and polymorphic layers of the hippocampus and the granule cell layer of the dentate gyrus. This distribution was similar to that obtained with the in situ hybridization technique. No glial staining was detected. Although the role of IGF-II in the adult rat brain, acting through its specific receptor, is not clear; in vitro and in vivo data suggest a possible neurotropic and/or neuromodulatory action.

Protein kinase C subspecies distinguish major cell types in rat hippocampus: an immunocytochemical and in situ hybridization histochemical study

This study compares the distribution of protein kinase C (PKC) alpha and beta with the distribution of PKC epsilon in the hippocampal formation of rats by immunocytochemistry and in situ hybridization histochemistry. Alpha and PKC beta are members of the group A PKC genes that were first described; PKC epsilon is a member of the group B PKC genes that were more recently identified by molecular cloning. A combination of all three gene products and their mRNAs overlapped in their distributions in dentate granule cells and pyramidal and nonpyramidal neurons. However, each subspecies predominated in one of the major cell types. PKC alpha-immunoreactivity and mRNA were most intense in CA2-3 pyramidal cells and dendrites, whereas PKC beta-immunoreactivity and mRNA were most intense in CA1 pyramidal cells and dendrites. PKC epsilon-immunoreactivity and mRNA were concentrated in dentate granule cells and CA3 pyramidal cells. Furthermore, PKC epsilon-immunoreactivity was detectable in mossy fibers. Each subspecies labeled different kinds of interneurons that were particularly numerous in, but not restricted to, the hilus. These data support the contention that different subtypes of hippocampal neurons are distinguished by the expression of different combinations of PKC subspecies under resting conditions.