Cumulative priming effects of cortical stimulation on smoking cue-induced craving

Smoking cue-provoked craving is an intricate behavior associated with strong changes in neural networks. Craving is one of the main reasons subjects continue to smoke; therefore interventions that can modify activity in neural networks associated with craving can be useful tools in future research investigating novel treatments for smoking cessation. The goal of this study was to use a neuromodulatory technique associated with a powerful effect on spontaneous neuronal firing - transcranial direct current stimulation (tDCS) - to modify cue-provoked smoking craving. Based on preliminary data showing that craving can be modified after a single tDCS session, here we investigated the effects of repeated tDCS sessions on craving behavior. Twenty-seven subjects were randomized to receive sham or active tDCS (anodal tDCS of the left DLPFC). Our results show a significant cumulative effect of tDCS on modifying smoking cue-provoked craving. In fact, in the group of active stimulation, smoking cues had an opposite effect on craving after stimulation - it decreased craving - as compared to sham stimulation in which there was a small decrease or increase on craving. In addition, during these 5 days of stimulation there was a small but significant decrease in the number of cigarettes smoked in the active as compared to sham tDCS group. Our findings extend the results of our previous study as they confirm the notion that tDCS has a specific effect on craving behavior and that the effects of several sessions can increase the magnitude of its effect. These results open avenues for the exploration of this method as a therapeutic alternative for smoking cessation and also as a mean to change stimulus-induced behavior. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

The contrasting role of heterochromatin in the differentiation of sex chromosomes: an overview from Neotropical fishes

During the evolutionary process of the sex chromosomes, a general principle that arises is that cessation or a partial restriction of recombination between the sex chromosome pair is necessary. Data from phylogenetically distinct organisms reveal that this phenomenon is frequently associated with the accumulation of heterochromatin in the sex chromosomes. Fish species emerge as excellent models to study this phenomenon because they have much younger sex chromosomes compared to higher vertebrates and many other organisms making it possible to follow their steps of differentiation. In several Neotropical fish species, the heterochromatinization, accompanied by amplification of tandem repeats, represents an important step in the morphological differentiation of simple sex chromosome systems, especially in the ZZ/ZW sex systems. In contrast, multiple sex chromosome systems have no additional increase of heterochromatin in the chromosomes. Thus, the initial stage of differentiation of the multiple sex chromosome systems seems to be associated with proper chromosomal rearrangements, whereas the simple sex chromosome systems have an accumulation of heterochromatin. In this review, attention has been drawn to this contrasting role of heterochromatin in the differentiation of simple and multiple sex chromosomes of Neotropical fishes, highlighting their surprising evolutionary dynamism.

Effects of Gastric Bypass Surgery in Patients With Type 2 Diabetes and Only Mild Obesity

OBJECTIVE-Roux-en-Y gastric bypass (RYGB) ameliorates type 2 diabetes in severely obese patients through mechanisms beyond just weight loss, and it may benefit less obese diabetic patients. We determined the long-term impact of RYGB on patients with diabetes and only class 1 obesity. RESEARCH DESIGN AND METHODS-Sixty-six consecutively selected diabetic patients with BMI 30-35 kg/m(2) underwent RYGB in a tertiary-care hospital and were prospectively studied for up to 6 years (median 5 years [range 1-6]), with 100% follow-up. Main outcome measures were safety and the percentage of patients experiencing diabetes remission (HbA(1c) <6.5% without diabetes medication). RESULTS-Participants had severe, longstanding diabetes, with disease duration 12.5 +/- 7.4 years and HbA(1c) 9.7 +/- 1.5%, despite insulin and/or oral diabetes medication usage in everyone. For up to 6 years following RYGB, durable diabetes remission occurred in 88% of cases, with glycemic improvement in 11%. Mean HbA(1c) fell from 9.7 +/- 1.5 to 5.9 +/- 0.1% (P < 0.001), despite diabetes medication cessation in the majority. Weight loss failed to correlate with several measures of improved glucose homeostasis, consistent with weight-independent antidiabetes mechanisms of RYGB. C-peptide responses to glucose increased substantially, suggesting improved beta-cell function. There was no mortality, major surgical morbidity, or excessive weight loss. Hypertension and dyslipidemia also improved, yielding 50-84% reductions in predicted 10-year cardiovascular disease risks of fatal and nonfatal coronary heart disease and stroke. CONCLUSIONS-This is the largest, longest-term study examining RYGB for diabetic patients without severe obesity. RYGB safely and effectively ameliorated diabetes and associated comorbidities, reducing cardiovascular risk, in patients with a BMI of only 30-35 kg/m(2).

Duration of dual antiplatelet therapy and outcomes after coronary stenting with the genous (TM) bio-engineered R stent (TM) in patients from the e-healing registry

Objective: We investigated the relation between duration of dual antiplatelet therapy (DAPT) and clinical outcomes up to 12 months after Genous (TM) endothelial progenitor cell capturing R stent (TM) placement in patients from the e-HEALING registry. Background: Cessation of (DAPT) has been shown to be associated with the occurrence of stent thrombosis (ST). After Genous placement, 1 month of DAPT is recommended. Methods: Patients were analyzed according to continuation or discontinuation of DAPT at a 30-day and 6-month landmark, excluding patients with events before the landmark. Each landmark was a new baseline, and outcomes were followed up to 12 months after stenting. The main outcome for our current analysis was target vessel failure (TVF), defined as target vessel-related cardiac death or myocardial infarction and target vessel revascularization. Secondary outcomes included ST. (Un)adjusted hazard ratios (HR) for TVF were calculated with Cox regression. Results: No difference was observed in the incidence of TVF [HR: 1.03; 95% confidence intervals (CI): 0.651.65, P = 0.89] in patients continuing DAPT (n = 4,249) at 30 days versus patients stopped (n = 309), and HR: 0.82 (95% CI: 0.551.23, P = 0.34) in patients continuing DAPT (n = 2,654) at 6 months versus patients stopped [n = 1,408] DAPT). Furthermore, no differences were observed in ST. Even after addition of identified independent predictors for TVF, adjusted TVF hazards were comparable. Conclusions: In a post-hoc analysis of e-HEALING, duration of DAPT was not associated with the occurrence of the outcomes TVF or ST. The Genous stent may be an attractive treatment especially in patients at increased risk for (temporary) cessation of DAPT or bleeding. (C) 2011 Wiley Periodicals, Inc.

Factors associated with smoking in the elderly: a health survey in Sao Paulo (ISA-SP)

This article reports on smoking prevalence and associated factors in the elderly, based on a population-based cross-sectional study with multistage sampling including 1,954 individuals 60 years or older living in four areas of Sao Paulo State, Brazil. Overall smoking prevalence was 12.2%, and higher rates were associated with male gender, age 60-69 years, not belonging to an Evangelical church, lower income, low body weight, lack of leisure-time physical activity, depression/anxiety, and hypertension. There was a high prevalence of smokers among individuals with a history of stroke, cancer, and chronic obstructive pulmonary disease. The results point to the need for effective interventions in healthcare services to promote smoking cessation among the elderly, since many are unable to stop on their own, even when they have tobacco-related illnesses. Special attention should be paid to individuals that depend on the National Health System, since smoking prevalence is higher in underprivileged socioeconomic groups.

Exercise Performance and Dynamic Hyperinflation in Lymphangioleiomyomatosis

Rationale: Lymphangioleiomyomatosis (LAM) is characterized by exercise performance impairment. Although airflow limitation is common, no previous studies have evaluated the prevalence and impact of dynamic hyperinflation (DH) in LAM. Objectives: To investigate the dynamic responses during maximal exercise and the prevalence, predictors, and repercussions of DH in LAM. Methods: Forty-two patients with LAM performed symptom-limited incremental cycle exercise and pulmonary functions tests (PFTs) and were compared with 10 age-matched healthy women. Dyspnea intensity, inspiratory capacity, oxygen saturation, and cardiac, metabolic, and respiratory variables were assessed during exercise. Patients with LAM also performed a 6-minute walk test (6MWT). Measurements and Main Results: Patients with LAM had higher baseline dyspnea, poorer quality of life, obstructive pattern, air trapping, and reduced diffusing capacity of carbon monoxide in PFTs. Although they had the same level of regular physical activity, their maximal exercise performance was reduced and was associated with ventilatory limitation, greater desaturation, and dyspnea. The prevalence of DH was high in LAM (55%), even in patients with mild spirometric abnormalities, and was correlated with airflow obstruction, air trapping, and diffusing capacity of carbon monoxide. Compared with the non-DH subgroup, the patients who developed DH had a ventilatory limitation contributing to exercise cessation on cycling and higher desaturation and dyspnea intensity during the 6MWT. Conclusions: Ventilatory limitation and gas exchange impairment are important causes of exercise limitation in LAM. DH is frequent in LAM, even in patients with mild spirometric abnormalities. DH was associated with the severity of disease, higher dyspnea, and lower oxygen saturation. In the 6MWT, desaturation and dyspnea were greater in patients with DH.

THE NEGATIVE EFFECTS OF ALCOHOL HANGOVER ON HIGH-ANXIETY PHENOTYPE RATS ARE INFLUENCED BY THE GLUTAMATE RECEPTORS OF THE DORSAL MIDBRAIN

Alcoholism is a chronic disorder characterized by the appearance of a withdrawal syndrome following the abrupt cessation of alcohol intake that includes symptoms of physical and emotional disturbances, anxiety being the most prevalent symptom. In humans, it was shown that anxiety may increase the probability of relapse. In laboratory animals, however, the use of anxiety to predict alcohol preference has remained difficult. Excitatory amino acids as glutamate have been implicated in alcohol hangover and may be responsible for the seizures and anxiety observed during withdrawal. The dorsal periaqueductal gray (DPAG) is a midbrain region critical for the modulation/expression of anxiety- and fear-related behaviors and the propagation of seizures induced by alcohol withdrawal, the glutamate neurotransmission being one of the most affected. The present study was designed to evaluate whether low- (LA) and high-anxiety rats (HA), tested during the alcohol hangover phase, in which anxiety is the most prevalent symptom, are more sensitive to the reinforcing effects of alcohol when tested in a voluntary alcohol drinking procedure. Additionally, we were interested in investigating the main effects of reducing the excitatory tonus of the dorsal midbrain, after the blockade of the ionotropic glutamate receptors into the DPAG, on the voluntary alcohol intake of HA and LA motivated rats that were made previously experienced with the free operant response of alcohol drinking. For this purpose, we used local infusions of the N-metil D-Aspartato (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-kainate receptors antagonist DL-2-Amino-7-phosphonoheptanoic acid - DL-AP7 (10 nmol/0.2 mu l) and L-glutamic acid diethyl ester - GDEE (160 nmol/0.2 mu l) respectively. Alcohol intoxication was produced by 10 daily bolus intraperitonial (IP) injections of alcohol (2.0 g/kg). Peak-blood alcohol levels were determined by gas-chromatography analysis in order to assess blood-alcohol content. Unconditioned and conditioned anxiety-like behavior was assessed by the use of the fear-potentiated startle procedure (FPS). Data collected showed that anxiety and alcohol drinking in HA animals are positively correlated in animals that were made previously familiarized with the anxiolytic effects of alcohol. In addition, anxiety-like behavior induced during alcohol hangover seems to be an effect of changes in glutamatergic neurotransmission into DPAG possibly involving AMPA/kainate and NMDA receptors, among others. (C) 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Evaluation of Adrenal Reserve in Children with Acute Lymphocytic Leukemia Treated with Prednisone or Dexamethasone

Background/Aims: The purpose of this study was to compare adrenal gland reserve in acute lymphocytic leukemia (ALL) patients 8 weeks after treatment with either prednisone (PRED) or dexamethasone (DEX) during the induction phase of therapy. Methods: A double-blind comparative study of patients treated with PRED and DEX was performed. Sixteen patients received PRED (40 mg/m(2)/day) and 13 patients received DEX (6 mg/m(2)/day), both for 28 days. A low-dose adrenocorticotropic hormone test (1.0 mu g/m(2), IV) was performed before and weekly for 8 weeks after abrupt cessation of glucocorticoid therapy. Sixteen children without ALL were used as controls to determine the cutoff peak cortisol level (14.2 mu g/dl). Results: Both groups (PRED and DEX) displayed similar mean peak cortisol levels before treatment and during the 8 weeks of evaluation (p = 0.652). No relationship was observed between the incidence of infection/stress and peak cortisol level within each group, nor was there a difference in the frequency of infection/stress between groups (p = 0.359). Although the patients presented variations in peak cortisol during the study period, no signs or symptoms of adrenal insufficiency were observed. Conclusion: Patients who received PRED or DEX for 4 weeks showed similar adrenal reserves and infection rates for 8 weeks after abruptly stopping glucocorticoid therapy, suggesting that DEX, which is a better antileukemic drug than PRED, has similar adrenal suppression and recovery rates. Copyright (c) 2012 S. Karger AG, Basel

Smoking: What Has Been Addressed in Brazilian Journals

The topic of tobacco smoking, in its several aspects, has been receiving increasing attention among researchers over the past few years, which has been reflected in more data and more solid scientific literature on the subject in national journals. This article aims to review the studies that focused on smoking published between January 2010 and June 2012, in Arquivos Brasileiros de Cardiologia (Brazilian Archives of Cardiology), Brazilian Journal of Medical and Biological Research, Clinics (Sao Paulo), Jornal Brasileiro de Pneumologia (Brazilian Journal of Pulmonology), Revista da Associacao Medica Brasileira (Journal of the Brazilian Medical Association) and Revista Brasileira de Cirurgia Cardiovascular (Brazilian Journal of Cardiovascular Surgery). During the aforementioned period 58 articles were published, 52 of which were original ones, addressing several aspects of smoking, such as effects on health, epidemiology, cessation and experimental studies.

Behavioral characterization of the alarm reaction and anxiolytic-like effect of acute treatment with fluoxetine in piaucu fish

In Ostariophysan fish, the detection of the alarm substance liberated into the water as a consequence of an attack by a predator elicits an alarm reaction or anti-predatory behavior. In this study, experiments were performed to: (i) describe and quantitatively characterize the behavioral and ventilatory responses in piaucu fish (Leporinus macrocephalus), individually and as part of a school, to conspecific alarm substance (CAS) and; (ii) test the effect of acute fluoxetine treatment on alarm reaction. Histological analysis revealed the presence of club cells in the intermediate and superficial layers of the epidermis. The predominant behavioral response to CAS was freezing for fish held individually, characterized by the cessation of the swimming activity as the animal settles to a bottom corner of the aquarium. Fish exposed to CAS showed decrease in the mean ventilatory frequency (approximately 13%) relative to control. In schools, CAS elicited a biphasic response that was characterized by erratic movements followed by increased school cohesion and immobility, reflected as an increased school cohesion (65.5% vs. -5.8% for controls) and in the number of animals near the bottom of the aquarium (42.0% vs. 6.5% for controls). Animals treated with single i.p. injections of fluoxetine (10 mu g/g b.w.) did not exhibit alarm behavior following CAS stimulation. These results show that an alarm pheromone system is present in piaucu fish, evidenced by the presence of epidermal club cells and an alarm reaction induced by CAS and consequently of a chemosensory system to transmit the appropriate information to neural structures responsible for initiating anti-predator behavioral responses. In addition, fluoxetine treatment caused an anxiolytic-like effect following CAS exposure. Thus, the alarm reaction in piaucu can be a useful model for neuroethological and pharmacological studies of anxiety-related states. (C) 2011 Elsevier Inc. All rights reserved.

Um novo escore para dependência a nicotina e uma nova escala de conforto do paciente durante o tratamento do tabagismo

O tabagismo é considerado a maior causa evitável de morbidade e mortalidade. O manuseio farmacológico da síndrome de abstinência de nicotina possibilita melhores taxas de cessação. Desenvolvemos um sistema de coleta de dados em nosso programa de assistência ao fumante, que inclui dois instrumentos novos: um escore para dependência de nicotina em fumantes de < 10 cigarros/dia e uma escala de conforto do paciente durante o tratamento do tabagismo. Descrevemos aqui os dois instrumentos, que estão em processo de validação.

Revisione critica dei risultati e nuovi algoritmi decisionali sulla chirurgia dell'OSAS

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is the periodic reduction or cessation of airflow during sleep. The syndrome is associated whit loud snoring, disrupted sleep and observed apnoeas. Surgery aims to alleviate symptoms of daytime sleepiness, improve quality of life and reduce the signs of sleep apnoea recordered by polysomnography. Surgical intervention for snoring and OSAHS includes several procedures, each designed to increase the patency of the upper airway. Procedures addressing nasal obstruction include septoplasty, turbinectomy, and radiofrequency ablation (RF) of the turbinates. Surgical procedures to reduce soft palate redundancy include uvulopalatopharyngoplasty with or without tonsillectomy, uvulopalatal flap, laser-assisted uvulopalatoplasty, and RF of the soft palate. More significant, however, particularly in cases of severe OSA, is hypopharyngeal or retrolingual obstruction related to an enlarged tongue, or more commonly due to maxillomandibular deficiency. Surgeries in these cases are aimed at reducing the bulk of the tongue base or providing more space for the tongue in the oropharynx so as to limit posterior collapse during sleep. These procedures include tongue-base suspension, genioglossal advancement, hyoid suspension, lingualplasty, and maxillomandibular advancement. We reviewed 269 patients undergoing to osas surgery at the ENT Department of Forlì Hospital in the last decade. Surgery was considered a success if the postoperative apnea/hypopnea index (AHI) was less than 20/h. According to the results, we have developed surgical decisional algorithms with the aims to optimize the success of these procedures by identifying proper candidates for surgery and the most appropriate surgical techniques. Although not without risks and not as predictable as positive airway pressure therapy, surgery remains an important treatment option for patients with obstructive sleep apnea (OSA), particularly for those who have failed or cannot tolerate positive airway pressure therapy. Successful surgery depends on proper patient selection, proper procedure selection, and experience of the surgeon. The intended purpose of medical algorithms is to improve and standardize decisions made in the delivery of medical care, assist in standardizing selection and application of treatment regimens, to reduce potential introduction of errors. Nasal Continuous Positive Airway Pressure (nCPAP) is the recommended therapy for patients with moderate to severe OSAS. Unfortunately this treatment is not accepted by some patient, appears to be poorly tolerated in a not neglible number of subjects, and the compliance may be critical, especially in the long term if correctly evaluated with interview as well with CPAP smart cards analysis. Among the alternative options in Literature, surgery is a long time honoured solution. However until now no clear scientific evidence exists that surgery can be considered a really effective option in OSAHS management. We have design a randomized prospective study comparing MMA and a ventilatory device (Autotitrating Positive Airways Pressure – APAP) in order to understand the real effectiveness of surgery in the management of moderate to severe OSAS. Fifty consecutive previously full informed patients suffering from severe OSAHS were enrolled and randomised into a conservative (APAP) or surgical (MMA) arm. Demographic, biometric, PSG and ESS profiles of the two group were statistically not significantly different. One year after surgery or continuous APAP treatment both groups showed a remarkable improvement of mean AHI and ESS; the degree of improvement was not statistically different. Provided the relatively small sample of studied subjects and the relatively short time of follow up, MMA proved to be in our adult and severe OSAHS patients group a valuable alternative therapeutical tool with a success rate not inferior to APAP.

Mobilisation von Schwermetallen im Bereich rheinhessisches Hügelland als Folge anthropogen bedingten Nitrateintrages - Folgen für den Grundwasserschutz ?

Kurzfassung Zielsetzung der vorliegenden Arbeit war eine hydrogeologische Untersuchung zur Herkunftsbestimmung der Grundwässer im Raum Alzey/Rheinhessen. Ein erster Anlaß zu weiteren Untersuchungen war durch erhöhte Schwermetallgehalte in den Rohwässern gegeben. Im Alzeyer Raum können Kluftgrundwasserleiter (Rotliegendes und z.T. verkarstetes Kalktertiär) sowie Porengrundwasserleiter (Tertiäre Meeressande und Ablagerungen des Quartärs) unterschieden werden. Aufgrund der Lösungsinhalte ergibt sich eine Typisierung in erdalkalische Hydrogenkarbonatwässer bzw. Austauschwässer, bei denen Erdalkalien durch Alkalien ersetzt wurden. Mit verschiedenen Grundwassermodellierungen konnten mögliche 'Grundwasserneubildungs-Pfade' aufgezeigt werden. Die 1996 durchgeführte Herabsetzung des Arsengrenzwertes zwang viele Versorgungsunternehmen weitere Verfahrenstechniken zur Grundwasseraufbereitung anzuwenden. Es zeigten sich erhebliche Schwierigkeiten bei der Umsetzung der EU-Wasserrahmenrichtlinie bezogen auf das lokale Untersuchungsgebiet Alzey. Schwermetallmobilisationen im Untergrund können aufgrund anthropogen eingetragener Nitrate im sonst reduzierenden Milieu ermöglicht werden. Mittels Tritium- und FCKW-Analysen konnten Alter bzw. Verweilzeiten der Wässer bestimmt werden. Zusammen mit den Werten von Deuterium und Sauerstoff-18, Schwefel-34 und Sauerstoff-18 aus dem im Wasser gelösten Sulfat und Stickstoff-15 und Sauerstoff-18 aus dem im Wasser gelösten Nitrat, konnten Aussagen über Änderungen im Aquifermilieu getroffen werden. Es zeigte sich, daß selbst bei einem völligen Stop des Düngemitteleintrages, die Schwermetallmobilisationen in Grundwässern im Bereich Rheinhessisches Hügelland innerhalb der nächsten 30 Jahre nicht abnehmen werden.

Evoluzione Morfotettonica delle Aree Alpine "Sempione" e "Brennero" attraverso Studi Termocronologici di bassa temperatura

E’ mostrata l’analisi e la modellazione di dati termocronologici di bassa temperatura da due regioni Alpine: il Sempione ed il Brennero. Le faglie distensive presenti bordano settori crostali profondi appartenenti al dominio penninico: il duomo metamorfico Lepontino al Sempione e la finestra dei Tauri al Brennero. I dati utilizzati sono FT e (U-Th)/He su apatite. Per il Sempione i dati provengono dalla bibliografia; per il Brennero si è provveduto ad un nuovo campionamento, sia in superficie che in sotterraneo. Gli attuali lavori per la galleria di base del Brennero (BBT), hanno consentito, per la prima volta, di raccogliere dati di FT e (U-Th)/He in apatite in sottosuolo per la finestra dei Tauri occidentale. Le analisi sono state effettuate tramite un codice a elementi finiti, Pecube, risolvente l’equazione di diffusione del calore per una topografia evolvente nel tempo. Il codice è stato modificato per tener conto dei dati sotterranei. L’inversione dei dati è stata effettuata usando il Neighbourhood Algorithm (NA), per ottenere il più plausibile scenario di evoluzione morfotettonico. I risultati ottenuti per il Sempione mostrano: ipotetica evoluzione dello stile tettonico della faglia del Sempione da rolling hinge a low angle detachment a 6.5 Ma e la cessazione dell’attività a 3 Ma; costruzione del rilievo fino a 5.5 Ma, smantellamento da 5.5 Ma ad oggi, in coincidenza dei cambiamenti climatici Messiniani e relativi all’inizio delle maggiori glaciazioni; incremento dell’esumazione da 0–0.6 mm/anno a 0.6–1.2 mm/anno a 2.4 Ma nell’emisfero settentrionale. I risultati al Brennero mostrano: maggiore attività tettonica della faglia del Brennero (1.3 mm/anno), maggiore attività esumativa (1–2 mm/anno) prima dei 10 Ma; crollo dell’attività della faglia del Brennero fra 10 Ma e oggi (0.1 mm/anno) e dell’attività esumativa nello stesso periodo (0.1–0.3 mm/anno); nessun aumento del tasso esumativo o variazioni topografiche negli ultimi 5 Ma.

Deciphering petrological signatures of reactive melt stagnation and cooling in the oceanic mantle underneath ultraslow-spreading ridges

The global mid-ocean ridge system creates oceanic crust and lithosphere that covers more than two-thirds of the Earth. Basalts are volumetrically the most important rock type sampled at mid-ocean ridges. For this reason, our present understanding of upper mantle dynamics and the chemical evolution of the earth is strongly influenced by the study of mid-ocean ridge basalts (MORB). However, MORB are aggregates of polybarically generated small melt increments that can undergo a variety of physical and chemical processes during their ascent and consequently affect their derivative geochemical composition. Therefore, MORB do not represent “direct” windows to the underlying upper mantle. Abyssal peridotites, upper mantle rocks recovered from the ocean floor, are the residual complement to MORB melting and provide essential information on melt extraction from the upper mantle. In this study, abyssal peridotites are examined to address these overarching questions posed by previous studies of MORB: How are basaltic melts formed in the mantle, how are they extracted from the mantle and what physical and chemical processes control mantle melting? The number of studies on abyssal peridotites is small compared to those on basalts, in part because seafloor exposures of abyssal peridotites are relatively rare. For this reason, abyssal peridotite characteristics need to be considered in the context of subaerially exposed peridotites associated with ophiolites, orogenic peridotite bodies and basalt-hosted xenoliths. However, orogenic peridotite bodies are mainly associated with passive continental margins, most ophiolites are formed in supra-subduction zone settings, and peridotite xenoliths are often contaminated by their host magma. Therefore, studies of abyssal peridotites are essential to understanding the primary characteristics of the oceanic upper mantle free from the influence of continental rifting, subduction and tectonic emplacement processes. Nevertheless, numerous processes such as melt stagnation and cooling-induced, inter-mineral exchange can affect residual abyssal peridotite compositions after the cessation of melting. The aim of this study is to address these post-melting modifications of abyssal peridotites from a petrological-geochemical perspective. The samples in this study were dredged along the axis of the ultraslow-spreading Gakkel Ridge in the Arctic Ocean within the “Sparsely Magmatic Zone”, a 100 km ridge section where only mantle rocks are exposed. During two expeditions (ARK XVII-2 in 2001 and ARK XX-2 in 2004), exceptionally fresh peridotites were recovered. The boulders and cobbles collected cover a range of mantle rock compositions, with most characterized as plagioclase-free spinel peridotites or plagioclase- spinel peridotites. This thesis investigates melt stagnation and cooling processes in the upper mantle and is divided into two parts. The first part focuses on processes in the stability field of spinel peridotites (>10 kb) such as melt refertilization and cooling related trace element exchange, while the second part investigates processes in the stability field of plagioclase peridotites (< 10 kb) such as reactive melt migration and melt stagnation. The dissertation chapters are organized to follow the theoretical ascent of a mantle parcel upwelling beneath the location where the samples were collected.