Absence of anti-rabphilin-3A antibodies in children and young adults with idiopathic central diabetes insipidus: a potential clue to elucidating a tumor etiology.

BACKGROUND: Central diabetes insipidus (CDI) is a rare condition caused by various underlying diseases, including neoplasms, autoimmune diseases, and infiltrative diseases. Differentiating between CDI etiologies is difficult. What has initially been classified as "idiopathic" central diabetes insipidus might in fact underlie various pathogenic mechanisms that are less understood to date and/or are not obvious at initial presentation. Therefore, even if idiopathic CDI is diagnosed at the time of onset, it is common for tumors such as germinoma to develop during surveillance. Crucially, a delayed diagnosis of germinoma may be associated with a worse prognosis. Recently, the presence of anti-rabphilin-3A antibodies has been found to be a highly sensitive and specific marker of lymphocytic infundibuloneurohypophysitis, an autoimmune-mediated CDI. CASE PRESENTATION: We herein present two cases, namely, a 13-year-old boy (patient 1) and a 19-year-old young man (patient 2) who were diagnosed with idiopathic CDI. In both patients, panhypopituitarism developed. Magnetic resonance imaging revealed pituitary stalk thickening and pituitary swelling approximately 1 1/2 years after the onset of CDI. Western blotting did not reveal the presence of anti-rabphilin-3A antibodies in serum in either patient, suggesting that autoimmune mechanisms might not be involved. Both patients were subsequently diagnosed with germinoma on pathological examination. They received chemotherapy, followed by radiation therapy. Notably, testosterone and insulin-like growth factor-1 levels normalized, and libido and beard growth recovered after chemoradiotherapy in patient 2. CONCLUSION: Our data suggest that the absence of anti-rabphilin-3A antibodies in young patients clinically diagnosed with idiopathic CDI may increase the probability of the development of non-lymphocytic lesions, including germinoma. We thus recommend a more attentive approach at the onset of these diseases.

Pituitary Stalk Thickening: Causes and Consequences. The Children's Memorial Health Institute Experience and Literature Review.

Background: Pituitary stalk thickening (PST) is a rare abnormality in the pediatric population. Its etiology is heterogeneous. The aim of the study was to identify important clinical, radiological and endocrinological manifestations of patients with PST and follow the course of the disease. Materials and Methods: It is a study conducted in 23 patients (13 boys) with PST with/without central diabetes insipidus (CDI) diagnosed between 1990 and 2020 at Children's Memorial Health Institute (CMHI) in Warsaw, Poland. We analyzed demographic data, clinical signs and symptoms, radiological findings, tumor markers, hormonal results, treatment protocols and outcomes. Results: The median age at the diagnosis of PST was 9.68 years (IQR: 7.21-12.33). The median time from the onset of the symptoms to the diagnosis was 2.17 years (IQR: 1.12-3.54). The most common initially reported manifestations were polydipsia, polyuria and nocturia (82.6%); most of the patients (56.5%) also presented decreased growth velocity. Hormonal evaluation at the onset of PST revealed: CDI (91.3%), growth hormone deficiency (GHD) (56.5%), hyperprolactinemia (39%), central hypothyroidism (34.8%), adrenal insufficiency (9%), precocious puberty (8.7%). The majority of the patients were diagnosed with germinoma (seventeen patients - 73.9%, one of them with teratoma and germinoma). Langerhans cell histiocytosis (LCH) was identified in three patients (multisystem LCH in two patients, and unifocal LCH in one patient). A single case of atypical teratoid rhabdoid tumor, suspected low-grade glioma (LGG) and lymphocytic infundibuloneurohypophysitis (LINH). The overall survival rate during the observational period was 87.0%. Conclusions: The pituitary infundibulum presents a diagnostic imaging challenge because of its small size and protean spectrum of disease processes. Germinoma should be suspected in all children with PST, especially with CDI, even when neurological and ophthalmological symptoms are absent.

Central Diabetes Insipidus Caused by Arginine Vasopressin Gene Mutation: Report of a Novel Mutation and Review of Literature.

Familial neurohypophyseal diabetes insipidus (FNDI) is an autosomal dominant hereditary disorder characterized by severe polydipsia and polyuria that usually presents in early childhood. In this study, we describe a new arginine vasopressin (AVP) gene mutation in an ethnic German family with FNDI and provide an overview of disease-associated AVP-gene mutations that are already described in literature. Three members of a German family with neurohypophyseal diabetes insipidus were studied. Isolated DNA from peripheral blood samples was used for mutation analysis by sequencing the whole coding region of AVP-NPII gene. Furthermore, we searched the electronic databases MEDLINE (Pubmed) as well as HGMD, LOVD-ClinVar, db-SNP and genomAD in order to compare our cases to that of other patients with FNDI. Genetic analysis of the patients revealed a novel heterozygote missense mutation in exon 2 of the AVP gene (c.274T>G), which has not yet been described in literature. We identified reports of more than 90 disease-associated mutations in the AVP gene in literature. The novel mutation of the AVP gene seems to cause FNDI in the presented German family. Similar to our newly detected mutation, most mutations causing FNDI are found in exon 2 of the AVP gene coding for neurophysin II. Clinically, it is important to think of FNDI in young children presenting with polydipsia and polyuria.

Central diabetes insipidus and pituitary stalk thickening in adults: distinction of neoplastic from non-neoplastic lesions.

CONTEXT: Association of central diabetes insipidus (CDI) and pituitary stalk thickening (PST) may have several etiologies (including malignancies) and differential diagnosis remains often difficult. OBJECTIVE: The purpose of this study was to identify which clinical, biochemical or radiological features could help clinicians to make an etiological diagnosis, especially distinguishing neoplastic from non-neoplastic pituitary stalk lesions. DESIGNS AND METHODS: We retrospectively analyzed clinical, biochemical, radiological and histological data of 38 adult patients diagnosed with CDI and PST of proven etiology. RESULTS: Of the 38 pituitary stalk lesions included, 11 (29%) were neoplastic. A histopathological diagnosis was obtained in 22/38 (58%) patients. The three most frequently observed etiologies of PST were neuroinfundibulitis (34%), germinoma (21%) and histiocytosis (18%). Pituitary stalk thickness was larger for neoplastic lesions, particularly germinomas. Male gender and a very young age were statistically associated with a risk of germinoma. At least one anterior pituitary deficit was observed in nearly 60% of patients. Patients with neoplastic PST were more affected by multiple anterior pituitary dysfunction than patients with benign PST. A high serum prolactin level was individually the best predictor of a neoplastic origin (90% sensitivity and 60% specificity for a serum prolactin level 1.27-fold above the normal upper limit (ULN)). CONCLUSION: We confirm a relatively high risk of malignancy in adult patients presenting with the association of CDI and PST. Young age, male gender, a very large thickening of the stalk, multiple anterior pituitary deficits and prolactin above 1.3× ULN increase the likelihood of a neoplastic origin.

A homozygote frameshift mutation in OCLN gene result in Pseudo-TORCH syndrome type I: A case report extending the phenotype with central diabetes insipidus and renal dysfunction.

Intrauterine infections with the pathogens, including toxoplasmosis, other (syphilis, varicella, mumps, parvovirus, and HIV), rubella, cytomegalovirus, and herpes simplex (TORCH) in susceptible individuals during pregnancy, result in microcephaly, white matter disease, cerebral atrophy, and calcifications in the fetus. Pseudo-TORCH syndrome is an umbrella term, consisting of several syndromes, resultant from different genetic alterations and pathogenetic mechanisms. Band-like calcification with simplified gyration and polymicrogyria (BLC-PMG) is one of these conditions, resultant from biallelic mutations in the OCLN gene, located in the chromosome 5q13.2. OCLN gene encodes occludin, a tight junction protein, which is expressed in the endothelia. The absence of occludin in the developing brain subsequently results in abnormal blood-brain barrier, thus immune-cell mediated tissue damage and cortical malformation. Herein, we present a pediatric patient who had progressive microcephaly, spasticity, multi-drug resistant epilepsy, PMG and intracranial band-type calcifications, accompanied by central diabetes insipidus and renal dysfunction. Whole exome sequencing revealed a homozygote W58Ffs*10 (c.173_194del) frameshift mutation in the OCLN gene. Of 34 BLC-PMG cases with demonstrable OCLN mutations, only three had renal manifestations, which is responsible for the majority of the demises. This is the first case diagnosed as having central diabetes insipidus and responded to desmopressin treatment to the best of our knowledge, however, this clinical improvement could not prevent the patient from renal dysfunction. The patient deceased at four years of age from sepsis, therefore early diagnosis, optimal follow-up for renal involvement and infection prevention measures are necessary for the patients with BLC-PMG.

Clinical Characteristics of Pediatric Patients With Sellar and Suprasellar Lesions Who Initially Present With Central Diabetes Insipidus: A Retrospective Study of 55 Cases From a Large Pituitary Center in China.

Purpose: To increase knowledge for the early differential diagnosis and accurate therapeutic strategies for pediatric patients with sellar or suprasellar region (SSR) lesions who initially present with central diabetes insipidus (CDI). Methods: This is a retrospective review of 55 pediatric patients (≤14 years old) with identified lesions in the SSR who initially presented with CDI at a large pituitary center between 2012 and 2018. The following data were summarized: demographic, clinical, endocrine, and neuroimaging data, intraoperative findings, histopathological findings, treatments, and prognosis. Results: In our group, the etiologies of the SSR lesions included germ cell tumors (GCTs, 74.5%), Langerhans cell histiocytosis (LCH, 18.2%), and craniopharyngioma (CP, 7.3%). Almost all patients (50/55, 90.9%) showed anterior pituitary dysfunction [multiple axes dysfunction (38), and isolated axis dysfunction (14)], while the GH/IGF-I axis was the most affected. Most GCT patients presented with various clinical manifestations besides CDI and had elevated ß-HCG, whereas LCH and CP patients mostly presented few non-specific symptoms besides CDI and most had normal level tumor markers. Sellar MRI demonstrated that posterior pituitary bright spot disappearance occurred in all patients, and pituitary stalk thickening was observed in 96.7% of patients. Treatment varied due to the different etiologies of the SSR lesions. After follow-up for 35.4 ± 20.2 months, the proportions of patients who needed AVP (arginine vasopressin) for GCT, LCH, and CP were 86.5, 100, and 75%, respectively, and the proportions of patients who needed HRT were 89.2, 50, and 75%, respectively. Conclusion: For pediatric SSR lesions that first manifest as CDI, we should comprehensively consider clinical characteristics and imaging features to aid in their early differential diagnosis. Tumor markers and surgical histopathology are also great complements for the differential diagnosis. Additionally, various treatment strategies should be adopted according to different causes to improve the child's prognosis and quality of life.

Forty-One Individuals With Mutations in the AVP-NPII Gene Associated With Familial Neurohypophyseal Diabetes Insipidus.

CONTEXT: Familial neurohypophyseal diabetes insipidus is a rare disease produced by a deficiency in the secretion of antidiuretic hormone and is caused by mutations in the arginine vasopressin gene. OBJECTIVE: Clinical, biochemical, and genetic characterization of a group of patients clinically diagnosed with familial neurohypophyseal diabetes insipidus, 1 of the largest cohorts of patients with protein neurophysin II (AVP-NPII) gene alterations studied so far. DESIGN: The AVP-NPII gene was screened for mutations by PCR followed by direct Sanger sequencing in 15 different unrelated families from Spain. RESULTS: The 15 probands presented with polyuria and polydipsia as the most important symptoms at the time of diagnosis. In these patients, the disease was diagnosed at a median of 6 years of age. We observed 11 likely pathogenic variants. Importantly, 4 of the AVP-NPII variants were novel (p.(Tyr21Cys), p.(Gly45Ser), p.(Cys75Tyr), p.(Gly88Cys)). CONCLUSIONS: Cytotoxicity seems to be due to consequences common to all the variants found in our cohort, which are not able to fold correctly and pass the quality control of the ER. In concordance, we found autosomal dominant familial neurohypophyseal diabetes insipidus in the 15 families studied.

Role of protein aggregation and degradation in autosomal dominant neurohypophyseal diabetes insipidus.

This review focuses on the cellular and molecular aspects underlying familial neurohypophyseal diabetes insipidus (DI), a rare disorder that is usually transmitted in an autosomal-dominant fashion. The disease, manifesting in infancy or early childhood and gradually progressing in severity, is caused by fully penetrant heterozygous mutations in the gene encoding prepro-vasopressin-neurophysin II, the precursor of the antidiuretic hormone arginine vasopressin (AVP). Post mortem studies in affected adults have shown cell degeneration in vasopressinergic hypothalamic nuclei. Studies in cells expressing pathogenic mutants and knock-in rodent models have shown that the mutant precursors are folding incompetent and fail to exit the endoplasmic reticulum (ER), as occurs normally with proteins that have entered the regulated secretory pathway. A portion of these mutants is eliminated via ER-associated degradation (ERAD) by proteasomes after retrotranslocation to the cytosol. Another portion forms large disulfide-linked fibrillar aggregates within the ER, in which wild-type precursor is trapped. Aggregation capacity is independently conferred by two domains of the prohormone, namely the AVP moiety and the C-terminal glycopeptide (copeptin). The same domains are also required for packaging into dense-core secretory granules and regulated secretion, suggesting a disturbed balance between the physiological self-aggregation at the trans-Golgi network and avoiding premature aggregate formation at the ER in the disease. The critical role of ERAD in maintaining physiological water balance has been underscored by experiments in mice expressing wild-type AVP but lacking critical components of the ERAD machinery. These animals also develop DI and show amyloid-like aggregates in the ER lumen. Thus, the capacity of the ERAD is exceeded in autosomal dominant DI, which can be viewed as a neurodegenerative disorder associated with the formation of amyloid ER aggregates. While DI symptoms develop prior to detectable cell death in transgenic DI mice, the eventual loss of vasopressinergic neurons is accompanied by autophagy, but the mechanism leading to cell degeneration in autosomal dominant neurohypophyseal DI still remains unknown.

Isolated Langerhans cell histiocytosis in the hypothalamic-pituitary region: a case report.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a rare disease that mainly affects children, but this disease is significantly rarer in patients who are older than 15 years. In this disease, any organ can be involved. The skeleton, skin and lung are commonly affected, and isolated hypothalamic-pituitary (HP) involvement is relatively rare. Here we report a 17-year-old adolescent with isolated HP-LCH of enlarged pituitary stalk presented with central diabetes insipidus (CDI). CASE PRESENTATION: A 17-year-old male adolescent with polydipsia and polyuria accompanied with elevated serum sodium level and low urine osmolality for 3 weeks was referred to our hospital. After admission, hormonal evaluation showed that his growth hormone (GH) was slightly elevated, and serum osmolality and glucose were normal. The fluid deprivation-vasopressin test demonstrated CDI. Imaging examination showed an obvious thickening of the pituitary stalk. Lymphocytic hypophysitis, sarcoidosis and granulation tissue lesions were suspected. After oral 1-deamino-8-Darginine vasopressin (DDAVP) and prednisone were administered for 2 months, symptoms were relieved, and he discontinued taking the drugs by himself. On reexamination, imaging revealed changes in the size and shape of the pituitary stalk, with thickened nodules. Then, a diagnostic biopsy of the pituitary stalk lesion was performed. Immunohistochemistry confirmed the definitive diagnosis of LCH. The clinical symptoms subsided with oral hormone replacements. CONCLUSION: CDI is a rare symptom in children and adolescents. Most of the causes are idiopathic, while others are caused by central nervous system (CNS) disorders. Meanwhile, lymphocytic hypophysitis, germinoma, LCH and other CNS disorders can all present as thickening of the pituitary stalk, diffuse enlargement of the pituitary gland, and weakening of high signal intensity in the neurohypophysis on magnetic resonance imaging (MRI). The differential diagnosis among these diseases depends on immunohistochemistry evidence.

Magnetic resonance imaging and symptoms in patients with neurosarcoidosis and central diabetes insipidus.

INTRODUCTION: In the clinical setting, the diagnosis of neurosarcoidosis in patients with central diabetes insipidus (CDI) is typically based both on symptoms (i.e. polydipsia or polyuria) and brain magnetic resonance imaging (MRI) findings (e.g. pituitary abnormality). However, inconsistent changes in the patient's symptoms and brain MRI findings may occur during the clinical course of the disease. This review was performed to summarise the relationship between symptoms and brain MRI findings in previously reported cases of neurosarcoidosis with CDI. MATERIAL AND METHODS: Case studies of patients diagnosed with neurosarcoidosis with CDI were collected via a PubMed search of studies published through 30 June 2018. RESULTS: Thirteen eligible studies were reviewed (20 patients; 12 men, 8 women; mean age 33 years). Polydipsia or polyuria was the first symptom in 13 patients. The mean duration from disease onset to diagnosis was 3.4 months. Brain MRIs showed abnormal findings in the hypothalamus and pituitary for 17 patients. Immunosuppressive drugs were used in 17 patients. For 14 patients, MRI findings improved, while symptoms did not. CONCLUSION: Patients with both neurosarcoidosis and CDI symptoms often do not improve, despite the fact that brain MRI findings often improve following treatment. More studies involving detailed pathological analyses and longer follow-up periods are necessary.

A novel mechanism of autophagy-associated cell death of vasopressin neurons in familial neurohypophysial diabetes insipidus.

Familial neurohypophysial diabetes insipidus (FNDI), characterized by delayed-onset progressive polyuria and loss of arginine vasopressin (AVP) neuron, is an autosomal dominant disorder caused by AVP gene mutations. We previously generated a knock-in mouse model for FNDI, which recapitulated the phenotype of human FNDI. To address the mechanisms underlying AVP neuron loss, we subjected FNDI mice to intermittent water deprivation, which accelerated the phenotype and induced AVP neuron loss within a relative short period. Electron microscopic analyses revealed that aggregates were confined to a sub-compartment of the endoplasmic reticulum (ER), ER-associated compartment (ERAC), in AVP neurons of FNDI mice under normal conditions. In contrast, aggregates scattered throughout the dilated ER lumen, and phagophores, autophagosome precursors, emerged and surrounded the ER containing scattered aggregates in FNDI mice subjected to water deprivation for 4 weeks, suggesting that failure of ERAC formation leads to autophagy induction for degradation of aggregates. Furthermore, the cytoplasm was entirely occupied with large vacuoles in AVP neurons of FNDI mice subjected to water deprivation for 12 weeks, at which stage 30-40% of AVP neurons were lost. Our data demonstrated that although autophagy should primarily be a protective mechanism, continuous autophagy leads to gradual loss of organelles including ER, resulting in autophagy-associated cell death of AVP neurons in FNDI mice.

Functional ectopic neural lobe increases GAP-43 expression via PI3K/AKT pathways to alleviate central diabetes insipidus after pituitary stalk lesion in rats.

Central diabetes insipidus can occur after hypothalamic-hypophyseal tract injury. This injury is linked with a deficit in circulating vasopressin and oxytocin, which are produced in the supraoptic nuclei and the hypothalamic paraventricular nuclei. Previous studies indicate that an ectopic neural lobe forms after pituitary stalk lesion in rats, and while the relationship between an ectopic neural lobe and CDI outcomes is unclear, the underlying mechanisms are also unknown. Here, we report that two different CDI characteristics are shown in rats that underwent pituitary stalk electric lesion and are defined by two different groups classified as the recovery group and the no-recovery group. Rats showed an enlarged functional ectopic neural lobe at the lesion site with a low CDI index. Moreover, growth associated protein-43, p-PI3K and p-AKT were up-regulated in the unmyelinated fibers of the ectopic neural lobe. Our findings suggest that the enlarged structure formed a functional ectopic neural lobe after the pituitary stalk lesion, and its regeneration might influence the CDI outcome. This regeneration might be due to an increase in GAP-43 expression through the PI3K/AKT pathway.

Induced pluripotent stem cells derived from a patient with autosomal dominant familial neurohypophyseal diabetes insipidus caused by a variant in the AVP gene.

Autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI) is caused by variants in the arginine vasopressin (AVP) gene. Here we report the generation of induced pluripotent stem cells (iPSCs) from a 42-year-old man carrying an adFNDI causing variant in exon 1 of the AVP gene using lentivirus-mediated nuclear reprogramming. The iPSCs carried the expected variant in the AVP gene. Furthermore, the iPSCs expressed pluripotency markers; displayed in vitro differentiation potential to the three germ layers and had a normal karyotype consistent with the original fibroblasts. This iPSC line is useful in future studies focusing on the pathogenesis of adFNDI.

Clinical presentation and outcome of children with central diabetes insipidus associated with a self-limited or transient pituitary stalk thickening, diagnosed as infundibuloneurohypophysitis.

OBJECTIVE: Despite lymphocytic or autoimmune infundibuloneurohypophysitis (INH) is an increasingly recognized aetiology in children with central diabetes insipidus (CDI); clinical data on epidemiology (clinical evolution, predisposing factors, complications), diagnosis and management of this entity are limited and mostly based on published case reports. The aim of this study was to gain a broader insight in the natural history of this disease by analysing the clinical presentation, radiological pituitary stalk changes, associated autoimmunity and hormonal deficiencies in children with CDI and a self-limiting or transient stalk thickening (ST), diagnosed as autoimmune infundibuloneurohypophysitis, during the last 15 years in four Belgian university hospitals. DESIGN AND PATIENTS: The medical files of nine CDI patients with a ST at initial presentation and no signs of Langerhans cell histiocytosis or germinoma at presentation and/or during follow-up of more than 1.5 years were reviewed. RESULTS: Age at presentation ranged from 3 to 14 years. Two patients had a positive family history of autoimmunity. Three children presented with associated growth failure, two with nausea and one with long-standing headache. Median maximal diameter of the stalk was 4.6 mm (2.7-10 mm). Four patients had extra-pituitary brain anomalies, such as cysts. One patient had central hypothyroidism, and another had a partial growth hormone deficiency at diagnosis. Within a mean follow-up of 5.4 (1.5-15) years, stalk thickening remained unchanged in two patients, regressed in one and normalized in six children. CDI remained in all, while additional pituitary hormone deficiencies developed in only one patient. CONCLUSIONS: In this series of children INH with CDI as initial presentation, CDI was permanent and infrequently associated with anterior pituitary hormone deficiencies, despite a frequent association with nonstalk cerebral lesions.

CENTRAL DIABETES INSIPIDUS: CLINICAL CHARACTERISTICS AND LONG-TERM COURSE IN A LARGE COHORT OF ADULTS.

OBJECTIVE: Central diabetes insipidus (CDI) is a rare heterogeneous condition with various underlying causes. This study sought to increase the still-limited data on the clinical characteristics and long-term course in adults diagnosed with CDI. METHODS: Data on demographics, presentation, imaging findings, affected pituitary axes, treatment, and complications were collected retrospectively from the files of 70 adult patients with CDI followed at a referral endocrine clinic. RESULTS: Forty women and 30 men were included. Mean age was 46.8 ± 15 years at the time of this study and 29.3 ± 20 years at CDI diagnosis. Twenty-eight patients were diagnosed in childhood. Forty patients (57%) acquired CDI following surgery. Main sellar pathologies were: craniopharyngioma, 17 patients (11 diagnosed in childhood); Langerhans histiocytosis, 10 patients (5 diagnosed in childhood); 7 patients (all diagnosed as adults) had a growth hormone-secreting adenoma; 12 patients (17%; 6 diagnosed in childhood) had idiopathic CDI. At least one anterior pituitary axis was affected in 73% of the cohort: 59% had growth hormone deficiency, 56% hypogonadism, 55% central hypothyroidism, 44% adrenocorticotropic hormone-cortisol deficiency. Patients with postoperative/trauma CDI (n = 44) tended to have multiple anterior pituitary axes deficits compared to the nonsurgical group of patients. All patients were treated with vasopressin preparations, mostly nasal spray. Hyponatremia developed in 32 patients, more in women, and was severe (<125 mEq/L) in 10 patients. Hypernatremia (>150 mEq/L) was noticed in 5 patients. Overall, the calculated complication rate was 22 in 1,250 treatment-years. CONCLUSION: Most adult patients with CDI have anterior pituitary dysfunction. Stability is usually achieved with long-term treatment. Women were more susceptible to desmopressin complications, albeit with an overall relatively low complication rate. ABBREVIATIONS: ACTH = adrenocorticotropic hormone CDI = central diabetes insipidus GH = growth hormone MRI = magnetic resonance imaging.

Suprasellar Epidermoid Cyst with Atypical Imaging Findings.

A 65-year-old female presented with progressive unilateral vision loss leading to blindness and features of central diabetes insipidus (DI) for 3 months' duration. Imaging showed a well-circumscribed, lobulated, rim-enhancing suprasellar lesion with inhomogeneous diffusion restriction. Through a pterional trans-sylvian approach, subtotal resection was performed and histopathology revealed features of an epidermoid cyst. At 5 months' follow-up, she had improvement of her diabetes insipidus but no visual improvement. This paper presents a case of suprasellar epidermoid with atypical imaging findings.

Electron Microscopic Study of the Inner Medulla in Rat Kidneys under Conditions of Vasopressin Treatment Combined with Prostaglandin Synthesis Blockade.

Ultrastructural changes in cells of the renal inner medulla involved in the realization of the antidiuretic effect of vasopressin under conditions of prostaglandin synthesis blockade were studied in the kidneys of Wistar rats and endogenous vasopressin-deficient homozygous Brattleboro rats. The results indicated uniform trend to an increase in the number of clathrincoated vesicles under conditions of hormone treatment combined with prostaglandin synthesis blockade in animals with different neurohypophyseal status. These changes reflected translocation of aquaporins and an increase in the permeability of the collecting tubular epithelium for water. Brattleboro rats, but not Wistar rats, exhibited ultrastructural signs of synthesis activation in the epithelium and widening of the intercellular gaps, which could indicate more intense paracellular water transport.

Genetic forms of neurohypophyseal diabetes insipidus.

Neurohypophyseal diabetes insipidus is characterized by polyuria and polydipsia owing to partial or complete deficiency of the antidiuretic hormone, arginine vasopressin (AVP). Although in most patients non-hereditary causes underlie the disorder, genetic forms have long been recognized and studied both in vivo and in vitro. In most affected families, the disease is transmitted in an autosomal dominant manner, whereas autosomal recessive forms are much less frequent. Both phenotypes can be caused by mutations in the vasopressin-neurophysin II (AVP) gene. In transfected cells expressing dominant mutations, the mutated hormone precursor is retained in the endoplasmic reticulum, where it forms fibrillar aggregates. Autopsy studies in humans and a murine knock-in model suggest that the dominant phenotype results from toxicity to vasopressinergic neurons, but the mechanisms leading to cell death remain unclear. Recessive transmission results from AVP with reduced biologic activity or the deletion of the locus. Genetic neurohypophyseal diabetes insipidus occurring in the context of diabetes mellitus, optic atrophy, and deafness is termed DIDMOAD or Wolfram syndrome, a genetically and phenotypically heterogeneous autosomal recessive disorder caused by mutations in the wolframin (WFS 1) gene.