FLT3-targeted therapy restores GATA1 pathway function in NPM1/FLT3-ITD mutated acute myeloid leukaemia.

One-third of newly diagnosed adult acute myeloid leukaemia (AML) carry FLT3 mutations, which frequently occur together with nucleophosmin (NPM1) mutations and are associated with worse prognosis. FLT3 inhibitors are widely used in clinics with limitations due to drug resistance. AML cells carrying FLT3 mutations in both mouse models and patients present low expression of GATA1, a gene involved in haematopoietic changes preceding AML. Here, we show that FLT3 inhibition induces cellular responses and restores the GATA1 pathway and functions in NPM1/FLT3-ITD mutated AML, thus providing a new mechanism of action for this drug.

Subgroup comparison according to clinical phenotype and serostatus in autoimmune encephalitis: a multicenter retrospective study.

BACKGROUND AND PURPOSE: Autoimmune encephalitides (AE) include a spectrum of neurological disorders whose diagnosis revolves around the detection of neuronal antibodies (Abs). Consensus-based diagnostic criteria (AE-DC) allow clinic-serological subgrouping of AE, with unclear prognostic implications. The impact of AE-DC on patients' management was studied, focusing on the subgroup of Ab-negative-AE. METHODS: This was a retrospective multicenter study on patients fulfilling AE-DC. All patients underwent Ab testing with commercial cell-based assays (CBAs) and, when available, in-house assays (immunohistochemistry, live/fixed CBAs, neuronal cultures) that contributed to defining final categories. Patients were classified as Ab-positive-AE [N-methyl-d-aspartate-receptor encephalitis (NMDAR-E), Ab-positive limbic encephalitis (LE), definite-AE] or Ab-negative-AE (Ab-negative-LE, probable-AE, possible-AE). RESULTS: Commercial CBAs detected neuronal Abs in 70/118 (59.3%) patients. Testing 37/48 Ab-negative cases, in-house assays identified Abs in 11 patients (29.7%). A hundred and eighteen patients fulfilled the AE-DC, 81 (68.6%) with Ab-positive-AE (Ab-positive-LE, 40; NMDAR-E, 32; definite-AE, nine) and 37 (31.4%) with Ab-negative-AE (Ab-negative-LE, 17; probable/possible-AE, 20). Clinical phenotypes were similar in Ab-positive-LE versus Ab-negative-LE. Twenty-four/118 (20.3%) patients had tumors, and 19/118 (16.1%) relapsed, regardless of being Ab-positive or Ab-negative. Ab-positive-AE patients were treated earlier than Ab-negative-AE patients (P = 0.045), responded more frequently to treatments (92.3% vs. 65.6%, P < 0.001) and received second-line therapies more often (33.3% vs. 10.8%, P = 0.01). Delays in first-line therapy initiation were associated with poor response (P = 0.022; odds ratio 1.02; confidence interval 1.00-1.04). CONCLUSIONS: In-house diagnostics improved Ab detection allowing better patient management but was available in a patient subgroup only, implying possible Ab-positive-AE underestimation. Notwithstanding this limitation, our findings suggest that Ab-negative-AE and Ab-positive-AE patients share similar oncological profiles, warranting appropriate tumor screening. Ab-negative-AE patients risk worse responses due to delayed and less aggressive treatments.

Reproducibility of rectal tumor volume delineation using diffusion-weighted MRI: Agreement on volumes between observers.

PURPOSE: To retrospectively evaluate the inter-observer agreement between a radiologist and a radiation oncologist and volume differences, in T2 and diffusion-weighted (DWI) MRI of gross tumor volume (GTV) delineation, in rectal cancer patients. MATERIALS AND METHODS: Two observers, a radiologist and a radiation oncologist, delineated GTVs of 50 patients on T2-weighted MRI (T2GTV) and echo planar DWI (DWIGTV). Observers agreement was assessed using DICE index, Bland-Altman analysis and intra-class correlation coefficient (ICC). Student's t-test was used for GTV comparison. RESULTS: Median T2GTV and DWIGTV were 17.09±14.12 cm3 (1.92-62.03) and 12.79±12.31 cm3 (1.23-62.25) for radiologist, and 16.82±13.66 cm3 (1.78-65.9) and 13.72±12.77 cm3 (1.29-69.75) for radiation oncologist. T2GTV were significantly larger compared to DWIGTV (P<0.001 and P<0.001, for both observers). Mean DICE index for T2GTV and DWIGTV were 0.80±0.07 and 0.77±0.06. The mean difference between the two observers were 0.26cm3 (95% CI: -5.36 to 5.88) and -1.13cm3 (95% CI: -5.70 to 3.44) for T2 and DWI volumes. The ICC for T2 volumes was 0.989 (95% CI: 0.981-0.994) (P<0.001) and 0.992 (95% CI: 0.986-0.996) (P<0.001) for DWI volumes. CONCLUSION: DWI resulted in smaller volumes delineation compared to T2-weighted MRI. Substantial and almost perfect agreements were reported for DWIGTV and T2GTV between radiologist and radiation oncologist. Due to the fact that DWI could be considered a simple technique for volume delineation for radiation oncologist, DWI could be used to improve quality in radiation planning for an accurate boost volume delineation when a dose escalation is investigated.

The role of oral hygiene in head and neck cancer: results from International Head and Neck Cancer Epidemiology (INHANCE) consortium.

BACKGROUND: Poor oral hygiene has been proposed to contribute to head and neck cancer (HNC) risk, although causality and independency of some indicators are uncertain. This study investigates the relationship of five oral hygiene indicators with incident HNCs. METHODS: In a pooled analysis of 8925 HNC cases and 12 527 controls from 13 studies participating in the International Head and Neck Cancer Epidemiology Consortium, comparable data on good oral hygiene indicators were harmonized. These included: no denture wear, no gum disease (or bleeding), <5 missing teeth, tooth brushing at least daily, and visiting a dentist ≥once a year. Logistic regression was used to estimate the effects of each oral hygiene indicator and cumulative score on HNC risk, adjusting for tobacco smoking and alcohol consumption. RESULTS: Inverse associations with any HNC, in the hypothesized direction, were observed for <5 missing teeth [odds ratio (OR) = 0.78; 95% confidence interval (CI) 0.74, 0.82], annual dentist visit (OR = 0.82; 95% CI 0.78, 0.87), daily tooth brushing (OR = 0.83, 95% CI 0.79, 0.88), and no gum disease (OR = 0.94; 95% CI 0.89, 0.99), and no association was observed for wearing dentures. These associations were relatively consistent across specific cancer sites, especially for tooth brushing and dentist visits. The population attributable fraction for ≤ 2 out of 5 good oral hygiene indicators was 8.9% (95% CI 3.3%, 14%) for oral cavity cancer. CONCLUSION: Good oral hygiene, as characterized by few missing teeth, annual dentist visits, and daily tooth brushing, may modestly reduce the risk of HNC.

Comparative evaluation of novel biodegradable nanoparticles for the drug targeting to breast cancer cells.

Nanomedicine formulations such as biodegradable nanoparticles (nps) and liposomes offer several advantages over traditional routes of administration: due to their small size, nanocarriers are able to selectively accumulate inside tumours or inflammatory tissues, resulting in improved drug efficacy and reduced side effects. To further augment targeting ability of nanoparticles towards tumour cells, specific ligands or antibodies that selectively recognise biomarkers over-expressed on cancer cells, can be attached to the surface either by chemical bond or by hydrophilic/hydrophobic interactions. In the present work, Herceptin (HER), a monoclonal antibody (mAb) able to selectively recognise HER-2 over-expressing tumour cells (such as breast and ovarian cancer cells), was absorbed on the surface of nanoparticles through hydrophilic/hydrophobic interactions. Nps were prepared by a modified single emulsion solvent evaporation method with five different polymers: three commercial polyesters (poly(ε-caprolactone) (PCL), poly (D,L-lactide) (PLA) and poly (D,L-lactide-co-.glycolide) (PLGA)) and two novel biodegradable polyesterurethanes (PURs) based on Poly(ε-caprolactone) blocks, synthesised with different chain extenders (1,4-cyclohexane dimethanol (CDM) and N-Boc-serinol). Polyurethanes were introduced as matrix-forming materials for nanoparticles due to their high chemical versatility, which allows tailoring of the materials final properties by properly selecting the reagents. All nps exhibited a small size and negative surface charge, suitable for surface functionalisation with mAb through hydrophilic/hydrophobic interactions. The extent of cellular internalisation was tested on two different cell lines: MCF-7 and SK-BR-3 breast cancer cells showing a normal and a high expression of the HER-2 receptor, respectively. Paclitaxel, a model anti-neoplastic drug, was encapsulated inside all nps, and release profiles and cytotoxicity on SK-BR-3 cells were also assessed. Interestingly, PUR nps were superior to commercial polyester-based nps in terms of higher cellular internalisation and cytotoxic activity on the tested cell lines. Results obtained warrants further investigation on the application of these PUR nps for controlled drug delivery and targeting.

Platelet function normalization after a prasugrel loading-dose: time-dependent effect of platelet supplementation.

BACKGROUND: Hemostatic benefits of platelet transfusions in thienopyridine-treated acute coronary syndrome (ACS) patients may be compromised by residual metabolite in circulation. OBJECTIVES: To estimate the earliest time after a prasugrel loading-dose when added platelets are no longer inhibited by prasugrel's active metabolite. METHODS: Baseline platelet reactivity of healthy subjects (n=25, 30 ± 5 years, 68% male) on ASA 325 mg was tested using maximum platelet aggregation (MPA, ADP 20 µm) and VerifyNow(®) P2Y12 and was followed by a 60 mg prasugrel loading-dose. At 2, 6, 12 and 24 h post-dose, fresh concentrated platelets from untreated donors were added ex-vivo to subjects' blood, raising platelet counts by 0% (control), 40%, 60% and 80%. To estimate the earliest time when prasugrel's active metabolite's inhibitory effect on the added platelets ceases, platelet function in supplemented samples was compared across time-points to identify the time when effect of supplementation on platelet function stabilized (i.e. the increase in platelet reactivity was statistically similar to that at the next time-point). RESULTS: Supplemented samples showed concentration-dependent increases in platelet reactivity vs. respective controls by both MPA and VerifyNow(®) at all assessment time-points. For each supplementation level, platelet reactivity showed a sharp increase from 2 to 6 h but was stable (P=NS) between 6 and 12 h. CONCLUSIONS: The earliest measured time when supplemented platelets were not inhibited by circulating active metabolite of prasugrel was 6 h after a prasugrel loading-dose. These findings may have important implications for prasugrel-treated ACS patients requiring platelet transfusions during surgery.

Magnesium deficiency induces anxiety and HPA axis dysregulation: modulation by therapeutic drug treatment.

Preclinical and some clinical studies suggest a relationship between perturbation in magnesium (Mg(2+)) homeostasis and pathological anxiety, although the underlying mechanisms remain largely unknown. Since there is evidence that Mg(2+) modulates the hypothalamic-pituitary adrenal (HPA) axis, we tested whether enhanced anxiety-like behaviour can be reliably elicited by dietary Mg(2+) deficiency and whether Mg(2+) deficiency is associated with altered HPA axis function. Compared with controls, Mg(2+) deficient mice did indeed display enhanced anxiety-related behaviour in a battery of established anxiety tests. The enhanced anxiety-related behaviour of Mg(2+) deficient mice was sensitive to chronic desipramine treatment in the hyponeophagia test and to acute diazepam treatment in the open arm exposure test. Mg(2+) deficiency caused an increase in the transcription of the corticotropin releasing hormone in the paraventricular hypothalamic nucleus (PVN), and elevated ACTH plasma levels, pointing to an enhanced set-point of the HPA axis. Chronic treatment with desipramine reversed the identified abnormalities of the stress axis. Functional mapping of neuronal activity using c-Fos revealed hyper-excitability in the PVN of anxious Mg(2+) deficient mice and its normalisation through diazepam treatment. Overall, the present findings demonstrate the robustness and validity of the Mg(2+) deficiency model as a mouse model of enhanced anxiety, showing sensitivity to treatment with anxiolytics and antidepressants. It is further suggested that dysregulations in the HPA axis may contribute to the hyper-emotionality in response to dietary induced hypomagnesaemia. This article is part of a Special Issue entitled 'Anxiety and Depression'.

Norovirus gastroenteritis and seizures: an atypical case with neuroradiological abnormalities.

We describe an 8-year-old boy admitted because of prolonged seizures during norovirus gastroenteritis without any signs of encephalopathy. Blood tests were normal and cerebrospinal fluid examination resulted negative for both bacteria and viruses. A reverse transcriptase polymerase chain reaction revealed norovirus RNA in a stool sample. A cerebral computed tomography turned out to be normal whereas subsequent cerebral magnetic resonance imaging showed transitory signal abnormalities consistent with vasogenic edema. The post-ictal electroencephalogram revealed normal background activity with sporadic left posterior delta waves. The child was discharged after 10 days with an unremarkable physical examination. A cerebral magnetic resonance imaging and an electroencephalogram after 1 month were both negative. We report a new case of benign infantile convulsions due to norovirus gastroenteritis with neuroradiological abnormalities to the pertinent literature in order to improve knowledge about this disorder and increase the possibility of clarifying its pathogenesis.

Altered GABA transmission in a mouse model of increased trait anxiety.

Anxiety disorders are the most prevalent central nervous system diseases imposing a high social burden to our society. Emotional processing is particularly controlled by GABA-ergic transmission in the amygdala. Using in situ hybridization and immunohistochemistry we now investigated changes in the expression of GABA synthesizing enzymes (GAD65 and GAD67), GABA(A) (α1-5, ß1-3, γ1-2) and GABA(B) receptor subunits (GBBR1, GBBR2) in amygdaloid nuclei of high anxiety-related behavior (HAB) mice in comparison to mice selected for normal anxiety-related behavior (NAB). Levels of GAD65 and GAD67 mRNAs and protein, as well as those of GABA were increased in the amygdala of HAB mice. Relative to NAB controls, mRNA expression of the GABA(A) receptor subunits ß1, ß2 and γ2 was specifically increased in the basolateral amygdala of HAB mice while transcription of α5 and γ1 subunits was reduced in the central and medial amygdala. On the protein level, increases in ß2 and γ2 subunit immunoreactivities were evident in the basolateral amygdala of HAB mice. No change in GABA(B) receptor expression was observed. These findings point towards an imbalanced GABA-ergic neurotransmission in the amygdala of HAB mice. On the other hand, FosB, a marker for neuronal activity, was increased in principal neurons of the basolateral amygdala in HAB mice, reflecting activation of excitatory neurons, possibly as a consequence of reduced GABA-ergic tonic inhibition through α5 and γ1 containing receptors. Ultimately these mechanisms may lead to the compensatory activation of GABA transmission, as indicated by the increased expression of GAD65/67 in HAB mice.

Percutaneous ultrasonography-guided core needle biopsy of gastrointestinal lesions: what's its actual role in clinical practice? A retrospective study for safety and effectiveness.

PURPOSE: Endoscopic biopsy is commonly performed to obtain a pathological diagnosis of gastrointestinal (GI) lesions. When the lesions are submucosal, subserosal, or exophytic, endoscopic biopsy is often unsuccessful, and endoscopic ultrasound (EUS)-guided biopsy is considered the procedure of choice in these cases. Nevertheless, in some patients both endoscopic and EUS-guided biopsy are not indicated, or yield inconclusive cyto-histological results. The aim of this study was to assess the efficacy and safety of percutaneous ultrasonography (US)-guided biopsy of GI wall lesions, and to define its actual role in clinical practice. MATERIALS AND METHODS: A retrospective study was conducted on 45 consecutive US-guided biopsies of GI lesions. All biopsies were performed in patients unsuitable for endoscopic or EUS-guided biopsy, or with lesions inaccessible to endoscopic techniques, or with inconclusive results from endoscopic or EUS-guided biopsy. Biopsies were performed with an 18 or 20-gauge Tru-cut needle under US guidance. Biopsy results were compared with the final diagnosis that was based on surgical pathological findings or clinical instrumental follow-up of at least 20 months. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), overall accuracy, and complication rate of the procedure were calculated. RESULTS: One biopsy specimen (2.2 %) was inadequate for cyto-histologic examination. In the remaining 44 cases, US-guided biopsy correctly identified 39 / 40 (97.5 %) malignant lesions, and 4 / 4 (100 %) benign lesions. One case resulted in a false negative (2.2 %). The sensitivity, specificity, PPV, NPV, and overall diagnostic accuracy were 97.5 %, 100 %, 100 %, 80 % and 97.7 %, respectively. Including also the inadequate specimen into the analysis, they were 95.1 %, 100 %, 100 %, 66.7 % and 95.6 %, respectively. No procedure-related complications were observed. In ten cases (22.2 %), US-guided biopsy results made it possible to avoid unnecessary surgical exploration. CONCLUSION: Percutaneous US-guided core biopsy of GI wall lesions is an accurate and safe technique that makes it possible in select cases to obtain a correct pathological diagnosis and prevent unnecessary surgical exploration. Although it has been replaced by EUS-guided biopsy as the procedure of choice to sample submucosal or subserosal GI lesions, US-guided biopsy can still play a useful role in the diagnostic workup of GI lesions when endoscopy or EUS is unsuccessful for various reasons or yields inconclusive cyto-histological results.

Transthoracic ultrasonography-guided core needle biopsy of pleural-based lung lesions: prospective randomized comparison between a Tru-cut-type needle and a modified Menghini-type needle.

PURPOSE: The diagnostic yield of the different types of cutting needles used to perform transthoracic biopsy is scarcely investigated. Aim of the study was to compare a Tru-cut-type (TCT) needle and a modified Menghini-type needle (MMT) in ultrasonography (US)-guided biopsy of pulmonary lesions. MATERIALS AND METHODS: 307 subjects (191 males and 116 females, mean age 58 years) with peripheral lung lesions selected to undergo US-guided biopsy were randomized to undergo biopsy by using an 18-gauge TCT or MMT needle. The specimens were imprinted on two to three slides for cytology and then put into a formalin solution for histology. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy were calculated. Fisher's exact test was used to compare histology recovery rate (HRR), diagnostic accuracy, and diagnostic yield of the combination of cytology and histology in comparison with cytology alone and histology alone. RESULTS: 155 biopsies were performed using the MMT needle, 152 using the TCT needle. HRR was 112 / 155 (72.3 %) and 144 / 152 (94.7 %), respectively (p < 0.0001). Sensitivity, specificity, PPV, and NPV were 81.6 %, 100 %, 100 %, and 62 % for the former, respectively, and 93.6 %, 100 %, 100 %, and 86 % for the latter. A correct diagnosis was achieved in 133 / 155 biopsies (85.8 %) performed with the MMT needle, and in 145 / 152 biopsies (95.4 %) performed with the TCT needle (p = 0.0041). The combination of cytology and histology had a higher diagnostic yield than cytology alone (p < 0.001) and histology alone (p < 0.001). CONCLUSION: The TCT needle performs better than the MMT needle, and improves the diagnostic accuracy of US-guided transthoracic biopsy of superficial lung lesions.

Clinical features of sarcomatoid renal cell carcinoma causing bilateral urinary tract obstruction.

We report on a 52-year-old female patient hospitalized because of uremia due to bilateral urinary tract obstruction caused by bilateral sarcomatoid renal cell carcinoma (SRCC). Abdominal computed tomography with contrast showed a large mass on the left side, infiltrating the left kidney, while the right kidney was described as enlarged. The latter was investigated with sonographic angiography using contrast and selective arteriography of the renal arteries, demonstrating a pseudonodular area at the inferior pole of the right kidney. The patient underwent bilateral nephrectomy and chronic hemodialysis treatment; unfortunately, after one month she died from cachexia. To the best of our knowledge this is the first case to be reported on bilateral SRCC causing bilateral urinary tract obstruction.

Germinoma with synchronous involvement of midline and off-midline structures associated with progressive hemiparesis and hemiatrophy in a young adult.

INTRODUCTION: Cerebral germinomas, the most common and least malignant intracranial germ cell tumors, usually arise in the pineal or suprasellar region and have characteristic clinical and radiological features. Germinomas more rarely occur in the thalamus, basal ganglia, and internal capsule, causing sometimes cerebral hemiatrophy and hemiparesis. More rarely, other clinical features can be fever of unknown origin, visual disturbance, and neuropsychiatric symptoms. Cerebral hemiatrophy can precede the imaging depiction of the off-midline mass. CASE: The authors present the first case of cerebral germinoma with synchronous involvement of the midline and off-midline structures, with unusual clinical and radiological presentation. DISCUSSION: The literature is reviewed, and the pathogenesis, the clinical findings, the imaging, and the therapy are discussed.

Role of B-type natriuretic peptide in cardiovascular state monitoring in a hemodialysis patient with primary amyloidosis.

BACKGROUND: Cardiac involvement occurs in up to 50% of patients with primary or A amyloidosis (ALA) and is associated with very poor prognosis. B-type natriuretic peptide (BNP) has been proposed as a guide for treatment of heart failure patients and as an index of myocardial dysfunction in patients with ALA. Data about BNP dosage for cardiovascular monitoring of patients with ALA on renal replacement therapy are lacking. CASE: A 64 year old Caucasian man was admitted because of nephrotic syndrome in July 2003. Renal diagnosis was ALA. Melphalan and prednisolone were given but renal function worsened and in April 2004 standard bicarbonate hemodialysis was started. In March 2004 thalidomide was added to his therapy. During the follow-up ejection fraction was stable and was 65% on the contrary E/A ratio gradually increased and overtook 1. BNP plasma levels were increased and the values recorded during the follow-up were: 2505 pg/mL in October 2003 (normal reference values<100), 1827 in April 2004, 4006 in June 2004, 5000 in September 2004, 3750 in January 2005 and 1920 in April 2005. In September 2005 BNP was 3380 pg/mL. The patient was still alive after a follow-up longer than two years. CONCLUSION: In ALA patients a powerful prognostic role of BNP has been reported whose expression is increased in ventricular myocytes of patients with cardiac involvement. BNP level monitoring does not appear to be superior to standard echocardiography in evaluating cardiovascular status of uremic patients with ALA.

Efficacy of two different platinum- or anthracycline-containing chemotherapy regimens for the treatment of small cell lung cancer.

The records of 190 consecutive patients referred to our department to be treated for small cell lung cancer were retrospectively evaluated, and the outcomes were compared on the basis of their first-line treatment. 113 patients were treated with 4-6 courses of cyclophosphamide, epidoxorubicin and etoposide (CEVP16), 77 with 4-6 courses of carboplatin and etoposide (CBE). 72 patients had limited disease and 118 extensive disease. Response rates were 58.4% for CEVP16 and 28.6% for CBE (p=0.0001), with no significant difference in the time to progression (255 vs 246 days, p=0.21). Overall survival was 334 days and 212 days, and the 1-year survival rate was 46% and 22.1%, respectively (p=0.0018). In patients with limited disease, overall survival was 434 days and 249 days (p=0.08) in both treatment group respectively and 281 and 208 days in those with extensive disease, respectively (p=0.02). No difference in side effects was observed between the two groups of patients. Our data suggest a role for anthracycline-containing regimens as first-line treatment of small cell lung cancer.

Evaluation of a new rapid immunoassay for the detection of Helicobacter pylori in faeces: a prospective pilot study.

BACKGROUND: Detection of Helicobacter pylori antigen in faeces is a valid method to diagnose H. pylori infection. Presently available stool tests are performed in the laboratory, and diagnostic report is delayed. AIM: To evaluate a new rapid stool test in a pre-treatment setting and to compare it with a validated laboratory stool test. METHODS: A total of 105 patients underwent gastroscopy with brush cytology, and biopsies for histology and rapid urease test, to assess H. pylori presence. Helicobacter pylori-status was considered positive if at least two tests were positive; negative if all tests were negative; indeterminate if one test was positive and two negative. Stool specimens were tested using either a rapid immunoassay kit (ImmunoCard STAT) or a laboratory enzyme immunoassay kit (Hp StAR). RESULTS: Sixty patients were infected with H. pylori, 44 non-infected, one indeterminate. The sensitivity and specificity of ImmunoCard STAT were 85 and 93%; those of Hp StAR were 88 and 100% (not significant). CONCLUSIONS: ImmunoCard STAT seems a reliable method for detecting H. pylori in untreated patients. It could replace laboratory stool tests, as it is easy and can be performed quickly. These characteristics might be a breakthrough for diagnosing H. pylori in the doctor's office.

Genetic functional inactivation of neuronal nitric oxide synthase affects stress-related Fos expression in specific brain regions.

To identify neuronal substrates involved in NO/stress interactions we used Fos expression as a marker and examined the pattern of neuronal activation in response to swim stress in nNOS knock-out (nNOS-/-) and wild-type (WT) mice. Forced swimming enhanced Fos expression in WT and nNOS-/- mice in several brain regions, including cortical, limbic and hypothalamic regions. Differences in the Fos response between the two groups were observed in a limited set (6 out of 42) of these brain areas only: nNOS-/- mice displayed increased stressor-induced Fos expression in the medial amygdala, periventricular hypothalamic nucleus, supraoptic nucleus, CA1 field of the hippocampus, dentate gyrus and infralimbic cortex. No differences were observed in regions including the septum, central amygdala, periaqueductal grey and locus coeruleus. During forced swimming, nNOS-/- mice displayed reduced immobility duration, while no differences in general locomotor activity were observed between the groups in the home cage and during the open field test. The findings indicate that deletion of nNOS alters stress-coping ability during forced swimming and leads to an altered pattern of neuronal activation in response to this stressor in specific parts of the limbic system, hypothalamus and the medial prefrontal cortex.