Influence of SENSE on image properties in high-resolution single-shot echo-planar DTI.

Limited spatial resolution is a key obstacle to the study of brain white matter structure with diffusion tensor imaging (DTI). In its frequent implementation with single-excitation spin-echo echo-planar sequences, DTI's ability to resolve small structures is strongly restricted by T2 and T2* decay, B0 inhomogeneity, and limited signal-to-noise ratio (SNR). In this work the influence of sensitivity encoding (SENSE) on diffusion-weighted (DW) image properties is investigated. Computer simulations showed that the PSF becomes narrower with increasing SENSE reduction factors, R, enhancing the intrinsic resolution. After a brief theoretical discussion, we describe the estimation of SNR on a pixel-by-pixel basis as a function of R. The mean image SNR behavior is manifold: SENSE is capable of increasing SNR efficiency by reducing the echo time (TE). Each SNR(R) curve reveals a maximum that depends on the amount of partial Fourier encoding used. The overall best SNR efficiency for an eight-element head coil array and a b-factor of 1000 s/mm2 is achieved at R = 2.1 and partial Fourier encoding of 60%. In vivo tensor maps of volunteers and a patient, with an in-plane resolution of 0.78 x 0.78 mm2, are also presented to demonstrate the practical implementation of the parallel approach.     

Primary aspergillosis of the sphenoid sinus with pituitary invasion – a rare differential diagnosis of sellar lesions

Summary Aspergillosis belongs to the group of mycotic diseases of paranasal sinuses. The invasive forms, and particularly the fulminant forms, are potentially fatal. Isolated aspergillosis of the sphenoid sinus or the clivus is a difficult diagnosis, since the often misleading clinical manifestations of this rare disease develop late. These patients become apparent by neurological signs such as cavernous sinus syndrome, pseudotumor of the pituitary or the orbit. Diagnosis is often made intra-operatively or on histological examination. We report a case of invasive aspergillosis uniquely involving the sellar area revealed by clinical features suggesting a pseudotumor of the pituitary. Although such lesions are almost always seen in immune suppressed subjects, in our case, the patient was immune competent and had no past history of sinusitis. The question of whether, and when to perform limited or extensive surgery remains an issue for discussion, owing to the rarity of this disease honed by lack of experience. It depends on several factors: the kind of disease, the immunity, the subtype of invasive fungal sinusitis and the degree of tissue invasion.     

Central metabotropic glutamate receptors differentially participate in interleukin-1beta-induced mechanical allodynia in the orofacial area of conscious rats.

The present study investigated the role of central metabotropic glutamate receptors (mGluRs) in interleukin-1beta (IL-1beta)-induced mechanical allodynia and mirror-image mechanical allodynia in the orofacial area. Experiments were carried out on male Sprague-Dawley rats weighing 230 to 280 g. After administration of 0.01, 0.1, 1, or 10 pg of IL-1beta into a subcutaneous area of the vibrissa pad, we examined the withdrawal behavioral responses produced by 10 successive trials of an air-puff ramp pressure applied ipsilaterally or contralaterally to the IL-1beta injection site. Subcutaneous injection of IL-1beta produced mechanical allodynia and mirror-image mechanical allodynia in the orofacial area. Intracisternal administration of CPCCOEt, a mGluR1 antagonist, or MPEP, a mGluR5 antagonist, reduced IL-1beta-induced mechanical allodynia and mirror-image mechanical allodynia. Intracisternal administration of APDC, a group II mGluR agonist, or L-AP4, a group III mGluR agonist, reduced both IL-1beta-induced mechanical allodynia and mirror-image mechanical allodynia. The antiallodynic effect, induced by APDC or L-AP4, was blocked by intracisternal pretreatment with LY341495, a group II mGluR antagonist, or CPPG, a group III mGluR antagonist. These results suggest that groups I, II, and III mGluRs differentially modulated IL-1beta-induced mechanical allodynia, as well as mirror-image mechanical allodynia, in the orofacial area. PERSPECTIVE: Central group I mGluR antagonists and groups II and III mGluR agonists modulate IL-1beta-induced mechanical allodynia and mirror-image mechanical allodynia in the orofacial area. Therefore, the central application of group I mGluR antagonists or groups II and III mGluR agonists might be of therapeutic value in treating pain disorder.     

Obesity is Associated with Genetic Variants That Alter Dopamine Availability

Human and animal studies have implicated dopamine in appetite regulation, and family studies have shown that BMI has a strong genetic component. Dopamine availability is controlled largely by three enzymes: COMT, MAOA and MAOB, and by the dopamine transporter SLC6A3, and each gene has a well-characterized functional variant. Here we look at these four functional polymorphisms together, to investigate how heritable variation in dopamine levels influences the risk of obesity in a cohort of 1150, including 240 defined as obese (BMI ≥ 30). The COMT and SLC6A3 polymorphisms showed no association with either weight, BMI or obesity risk. We found, however, that both MAOA and MAOB show an excess of the low-activity genotypes in obese individuals ( MAOA: χ²= 15.45, p = 0.004; MAOB: χ²= 8.05, p = 0.018). Additionally, the MAOA genotype was significantly associated with both weight (p = 0.0005) and BMI (p = 0.001). When considered together, the 'at risk genotype' - low activity genotypes at both the MAOA and MAOB loci - shows a relative risk for obesity of 5.01. These results have not been replicated and, given the experience of complex trait genetics, warrant caution in interpretation. In implicating both the MAOA and MOAB variants, however, this study provides the first indication that dopamine availability (as opposed to other effects of MAOA) is involved in human obesity. It is therefore a priority to assess the associations in replication datasets.     

Chronic lymphocytic leukaemia and lymphoma in an Iranian fat-tailed sheep: a case report

A 5-year-old Iranian fat-tailed sheep was referred to the Veterinary Clinic of Shiraz University in September 2003 with a history of emaciation, fever, decreased appetite, lethargy and cough. Small cutaneous and subcutaneous nodules were palpable, especially under the ribs on both sides of the thorax. Discrete cutaneous plaques and large scabby lesions were also observed. Very large mammary gland lymph nodes were noticed on palpation. Haematological and serum biochemical values were estimated through standard haematological and biochemical techniques. In this case a normocytic–normochromic anaemia, leukocytosis and lymphocytosis were found. The concentrations of blood urea nitrogen (BUN), creatinine, cholesterol and the activities of aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) were higher than the values reported for sheep. Necropsy findings revealed that the lymph nodes were affected in most organs. Malignant lymphoma in the kidney, heart, spleen, mammary glands, liver and bone marrow was observed. The histopathological appearance of the affected tissues varied considerably, depending upon the degree of tumour infiltration. According to the history, clinical signs, laboratory findings, necropsy findings and histopathological examination the case was diagnosed as chronic lymphocytic leukaemia and lymphoma.     

Design of Case-controls Studies with Unscreened Controls

Traditionally in genetic case‐control studies controls have been screened to exclude subjects with a personal history of illness. This control group has the advantage of optimal power to detect loci involved in illness, but requires more work and may incur substantial cost in recruitment. An alternative approach to screening is to use unscreened controls sampled from the general population. Such controls are generally plentiful and inexpensive, but in general there is a risk that some may have the same disease as the cases, which will reduce power to detect associations. We have quantified the extent of this power loss, and produced mathematical formulae for the number of unscreened controls necessary to achieve the same power as a fixed sample of screened controls. The effect of using unscreened controls will also depend on the ratio of the number of screened controls to cases specified in the original study design, and this is also investigated. We have also investigated the cost‐benefits of the screened and unscreened approaches, according to variation in the relative costs of sampling screened and unscreened controls, together with genotyping costs. We have, thus, identified the range of situations in which using unscreened controls is a cost‐effective alternative to the screened control method and could be considered when designing a study. In many of the typical, real‐world situations in complex genetics, the use of unscreened controls is potentially cost‐effective and can, in general, be considered for disorders with population prevalence K_p < 0.2. With the steady reduction in genotyping costs and the availability of common sets of “population controls” this design is likely to become increasingly cost effective.     

Applications of biological control in resistant host-pathogen systems.

Insect pest species can have devastating effects on crops. Control of these insect pests is usually achieved by using chemical insecticides. However, there has been much cause for concern with their overuse. Consequently, research has been carried out into alternative forms of control, in particular biological control methods. Recent laboratory studies have indicated that these natural forms of control can induce resistant strains of insect pest. In this paper we present a discrete-time host-pathogen model to describe the interaction between a host (insect species) that can develop a resistant strain and a pathogen (biological control) that can be externally applied to the system. For this model we use a single-state variable for the host population. We show that the proportion of resistance in the population impacts on the viability of the host population. Moreover, when the host population does persist, we explore the interaction between host susceptibility and host population levels. The different scenarios which arise are explained ecologically in terms of trade-offs in intrinsic growth rates, disease susceptibility and intraspecific host competition for the resistant subclass.     

Radiolabelled monoclonal antibodies in oncology. III. Radioimmunotherapy

The requirements, problems and progress of radioimmunotherapy in the management of certain malignancies are described. The future prospects using a two- or three-stage approach are promising.     

Effects of halothane on spinal dorsal horn WDR(wide dynamic range) neuronal activity in cats

The effects of halothane (0.2%, 0.5%, and 1.0%) on the spinal dorsal horn wide dynamic range (WDR) neuronal activity was studied in either spinal cord intact or spinal transected cats. Extracellular activity was recorded in the dorsal horn from single WDR neurons responding to noxious and non-noxious stimuli applied to the cutaneous receptive fields on the left hind foot pads of intact or decerebrate, spinal cord transected (L 1-2) cats. When 10 micrograms of bradykinin was injected into the femoral artery ipsilateral to the recording site as the noxious test stimulus in the spinal cat, all of 7 WDR neurons gave excitatory responses which were not depressed by 0.2% and 0.5% halothane but were depressed significantly by 1.0%. On the other hand, when the injection of 10 micrograms of bradykinin into the femoral artery ipsilateral to the recording site was used in the intact cat, 7 of 14 WDR neurons (50%) gave excitatory responses, which were not depressed by 0.2% halothane but were significantly depressed by 0.5% and 1.0% halothane, and 7 of 14 WDR neurons (50%) gave inhibitory responses, which were significantly depressed by 0.2%, 0.5%, and 1.0% halothane. We have found that halothane reduces the excitation as well as the inhibition of dorsal horn WDR neuronal activity induced by bradykinin injection.