Phenylketonuria: reduced tyrosine brain influx relates to reduced cerebral protein synthesis.

Background: In phenylketonuria (PKU), elevated blood phenylalanine (Phe) concentrations are considered to impair transport of large neutral amino acids (LNAAs) from blood to brain. This impairment is believed to underlie cognitive deficits in PKU via different mechanisms, including reduced cerebral protein synthesis. In this study, we investigated the hypothesis that impaired LNAA influx relates to reduced cerebral protein synthesis.

Absolute quantitative total-body small-animal SPECT with focusing pinholes.

Purpose: In pinhole SPECT, attenuation of the photon flux on trajectories between source and pinholes affects quantitative accuracy of reconstructed images. Previously we introduced iterative methods that compensate for image degrading effects of detector and pinhole blurring, pinhole sensitivity and scatter for multi-pinhole SPECT. The aim of this paper is (1) to investigate the accuracy of the Chang algorithm in rodents and (2) to present a practical Chang-based method using body outline contours obtained with optical cameras.

Left ventricular volume assessment by planar radionuclide ventriculography evaluated by MRI.

Background: Assessment of left ventricular (LV) ejection fraction (LVEF) and LV volume are essential for the evaluation of prognosis in cardiac disease. LVEF and LV volumes can be measured with several imaging modalities, such as magnetic resonance imaging (MRI) or computed tomography; however, these are relatively expensive and time consuming. In contrast, planar radionuclide ventriculography (PRV) for LVEF assessment is a cost-effective, fast, and reliable technique, but PRV for LV volumes calculation is less common.

Phenylketonuria: High plasma phenylalanine decreases cerebral protein synthesis.

Left untreated, phenylketonuria biochemically results in high phenylalanine concentrations in blood and tissues, and clinically especially in severe mental retardation. Treatment consists of severe dietary restriction of phenylalanine with more or less normal intellectual outcome as result when started early enough. It is unclear whether treatment for life is necessary.

The diagnostic value of 124I-PET in patients with differentiated thyroid cancer.

Background: The purpose of this prospective study was to evaluate the clinical diagnostic value of iodine-124 (124I)-positron emission tomography (PET) in patients with advanced differentiated thyroid carcinoma (DTC) and to compare the 124I-PET imaging results with the 131I whole-body scan (WBS).

Materials And Methods: Twenty patients with histologically proven advanced DTC (including T4, extra-nodal tumour growth, or distant metastases) underwent diagnostic 131I-WBS, 124I-PET scan, and post-treatment 131I-WBS 4 months after ablation. The findings on the 124I-PET were compared with the findings on the diagnostic and post-therapeutic 131I-WBS and were also correlated with radiologic and/or cytological investigations.

Brain activation during human male ejaculation revisited.

In a prior [O]-H2O positron emission tomographic study we reported brain regions involved in human male ejaculation. Here, we used another, more recently acquired data set to evaluate the methodological approach of this previous study, and discovered that part of the reported activation pattern was not related to ejaculation. With a new analysis of these ejaculation data, we now demonstrate ejaculation-related activations in the deep cerebellar nuclei (dentate nucleus), anterior vermis, pons, and ventrolateral thalamus, and, most importantly, ejaculation-related deactivations throughout the prefrontal cortex.

Methylphenidate-induced activation of the anterior cingulate but not the striatum: a [15O]H2O PET study in healthy volunteers.

The dopaminergic system has been implicated in the pathogenesis and treatment of a variety of neuropsychiatric disorders, such as schizophrenia, depression, and addiction. (Dys)function of the dopaminergic system may be studied by combining [15O]H2O PET with a dopaminergic drug challenge. In this pilot study we investigated the suitability of the dopamine reuptake blocker methylphenidate (MP) as a dopaminergic probe.

Psychobiological characteristics of dissociative identity disorder: a symptom provocation study.

Background: Dissociative identity disorder (DID) patients function as two or more identities or dissociative identity states (DIS), categorized as 'neutral identity states' (NIS) and 'traumatic identity states' (TIS). NIS inhibit access to traumatic memories thereby enabling daily life functioning. TIS have access and responses to these memories.

Activations of "motor" and other non-language structures during sentence comprehension.

In this paper we report the results of an experiment in which subjects read syntactically unambiguous and ambiguous sentences which were disambiguated after several words to the less likely possibility. Understanding such sentences involves building an initial structure, inhibiting the non-preferred structure, detecting that later input is incompatible with the initial structure, and reactivating the alternative structure. The ambiguous sentences activated four areas more than the unambiguous sentences.

Brain activation during human male ejaculation.

Brain mechanisms that control human sexual behavior in general, and ejaculation in particular, are poorly understood. We used positron emission tomography to measure increases in regional cerebral blood flow (rCBF) during ejaculation compared with sexual stimulation in heterosexual male volunteers. Manual penile stimulation was performed by the volunteer's female partner.

Positron emission tomography: the conceptual idea using a multidisciplinary approach.

Positron emission tomography (PET) is a method for quantitatively measuring biochemical and physiological processes in vivo by using radiopharmaceuticals labeled with positron-emitting radionuclides such as 11C, 13N, 15O, and 18F and by measuring the annihilation radiation using a coincidence technique. This technique is also used for measurement of the pharmacokinetics of labeled drugs and measurement of the effects of drugs on metabolism. Deviations from normal metabolism can be measured and insight into biological processes responsible for diseases can be obtained.

rCBF differences between panic disorder patients and control subjects during anticipatory anxiety and rest.

Background: Our goal was to identify brain structures involved in anticipatory anxiety in panic disorder (PD) patients compared to control subjects.

Methods: Seventeen PD patients and 21 healthy control subjects were studied with H(2)(15)O positron emission tomography scan, before and after a pentagastrin challenge.

Results: During anticipatory anxiety we found hypoactivity in the precentral gyrus, the inferior frontal gyrus, the right amygdala, and the anterior insula in PD patients compared to control subjects.