Direct visualisation of B1 inhomogeneity by flip angle dependency

The toxicity of mercury ion, on Chlorella vulgaris, is largely influenced by amino acids. Five amino acids, namely alanine, asparagine, glutamic acid, cysteine and histidine, were added separately to the medium containing static dose of mercury. Survival (%) of the alga was reduced with the increasing concentrations of mercury. Of these five amino acids, cysteine was found to be the most effective while alanine and glutamic acid were the least effective on reducing the toxic effect of mercury on the alga measured in terms of growth, chlorophyll and protein content. The order of detoxification was Alanine < Glutamate < Asparargine < Histidine < Cysteine. Amino acids from ligands with Hg2+ making it less toxic to the alga and produce an additional source of energy for growth and development.     

Optimization of contrast delivery for pulmonary CT angiography

OBJECTIVE: The aim of this study was to evaluate the feasibility and reproducibility of a novel image-scoring method of first-trimester nuchal translucency measurement as an objective tool of ongoing audit and training. DESIGN: This was an independent evaluation of nuchal translucency images by three separate reviewers unaware of the examiner. SUBJECTS: There were 105 consecutive singleton pregnancies undergoing first-trimester screening. METHODS: Each image was scored according to the following criteria: section (oblique, 0; mid-sagittal, 2), caliper placing (misplaced, 0; proper, 2), skin line (nuchal only, 0; nuchal and back, 2), image size (unsatisfactory, 0; satisfactory, 1), amnion (not visualized, 0; visualized, 1) and head position (flexion/hyperextension, 0; straight, 1). The final score was categorized into one of four quality groups: excellent (8-9), reasonable (4-7), intermediate (2-3), unacceptable (0-1). RESULTS: The distributions of the four quality groups were similar between the three reviewers: 11.4% were classified as excellent, 57.1% as reasonable, 25.7% as intermediate and 5.7% as unacceptable. Inter-reviewer agreement showed identical classification, by each pair of reviewers, from 65.7% to 74.3%, and partial agreement to neighboring quality groups from 25.7% to 34.3% of the cases. In none of the cases did the reviewers differ in categorizing cases to remarkably different quality groups. Application of the auditing method to the examiners showed similar distribution to the various quality groups and similar mean final score of 4.69 (0.39, SE), 4.54 (0.15, SE) and 4.65 (0.15, SE). CONCLUSIONS: The described image-scoring method represents a new approach towards the evaluation of ultrasound performance as a whole and nuchal translucency measurement in particular. It may be employed by every center in an independent manner with minimal resources and regardless of the method of risk assessment. More studies will be needed to determine the standards required from the examiners and to elucidate the contribution of the proposed auditing method to the examination's quality and the process of training.     

T1a and T1b breast cancer: a twelve-year experience

To understand the prevalence of axillary node metastasis and survival of patients with T1a and T1b breast cancers, we reviewed the experience at a large community hospital. All patients in the William Beaumont Hospital tumor registry with breast cancer treated between January 1983 and November 1995 were evaluated for tumor size, age, cell type, and the presence or absence of axillary node disease. Long-term survival was evaluated in patients treated between 1983 and 1992. The patients were defined as premenopausal or postmenopausal based on age (49 years or less, premenopausal; 50 years or greater, postmenopausal). Of the 4590 patients treated for breast cancer from 1983 to 1995, 915 had tumors 1.0 cm or less in size. Of 181 patients who had T1a cancer, 27 were premenopausal, and 154 were postmenopausal. Twenty-three premenopausal patients had axillary lymph nodes examined, two (8.7%) had histologically positive lymph nodes. Of 118 postmenopausal patients who had axillary nodes examined, six (5.1%) had positive lymph nodes. In those with T1b tumors, 130 patients were premenopausal; 604 patients were postmenopausal. Of these, 119 premenopausal patients had axillary nodes examined, and 29 (24.4%) had positive lymph nodes. Of 464 postmenopausal patients who had axillary nodes examined, 66 (14.2%) had positive nodes. The overall, disease-free, and tumor-specific survival rates for patients with T1a tumors were 93.8, 87.5, and 93.8 per cent (premenopausal) and 86.2, 95.4, and 95.4 per cent (postmenopausal), respectively. These survival rates for patients with T1b tumors were 87.8, 87.8, and 91.1 per cent (premenopausal) and 82.9, 88.5, and 92.9 per cent (postmenopausal), respectively. Premenopausal T1b patients had a higher rate of nodal involvement than postmenopausal T1b patients (P = 0.011). Postmenopausal T1b patients had a higher nodal metastasis rate than postmenopausal T1a patients (P = 0.01). T1b patients had a higher rate of axillary involvement than did T1a patients (P = 0.0018). Based on the rate of axillary lymph node metastasis and survival statistics, there may be a role for axillary node dissection in select patients with tumors less than 1.0 cm. in size.     

Sezary cell leukaemia: a distinct T cell disorder or a variant form of T prolymphocytic leukaemia?

The binding of the 2 cyclic lactam MSH (4-10) analogues (MTII, SHU9119), and 5 cyclic [Cys4, Cys10] alpha-MSH analogues were tested on cells transiently expressing the human MC1, MC3, MC4 and MC5 receptors. The results indicate a differential importance of the C-terminal (Lys-Pro-Val) and N-terminal (Ser-Tyr-Ser) of cyclic [Cys4, Cys10] alpha-MSH analogues in binding to the MC receptor subtypes. Substitution of D-Phe7 by D-Nal(2')7 in both the cyclic lactam MSH (4-10) and the cyclic disulphide MSH (4-10) analogues resulted in a shift in favour of selectivity for the MC4 receptor; the disulphide analogue, [Cys4, D-Nal(2')7 Cys10] alpha-MSH (4-10) (HS9510), showing the highest selectivity for the MC4 receptor among all the substances tested. However, the cyclic lactams displayed an over all higher affinity for the MC receptors, than any of the cyclic disulphide MSH (4-10) analogues.     

Dual contrast enhancement of both T1- and T2-weighted sequences using ultrasmall superparamagnetic iron oxide

BMS 180549 (previously AMI-227), an ultrasmall superparamagnetic iron particulate agent, was investigated to determine its utility as a contrast agent on T1-weighted, as well as T2-weighted sequences, as a function of route of administration, (intravenous versus selective arterial) and concentration. Twelve farm pigs were divided into three groups of four each by route of administration (intravenous, selective superior mesenteric, or selective hepatic arterial injection). 10 mumol/kg and 20 mumol/kg dosages were given and evaluated both immediately after and 20-24 hr after contrast infusion, using both spin-echo and gradient-echo T1 and T2-weighted sequences. Significant postcontrast liver and spleen enhancement was noted at both concentrations, regardless of route of administration on both T1- and T2-weighted sequences. The earliest postcontrast T1-weighted sequence obtained during the 1-3 min interval following IV administration of high dose (20 mumol/kg) contrast demonstrated an average of +42.8% liver and +249.0% spleen enhancement; 24 hr later this decreased to 0 and 7.2%, respectively. The earliest postcontrast T2-weighted sequence obtained during the 8-17 min interval post high-dose IV contrast showed an average of -75.8% decrease in liver and -28.7% decrease in spleen signal intensity; 24 hr later the magnitude of these changes diminished to -33.1% and +2.5%, respectively. No significant difference was noted in liver or spleen enhancement, regardless of route of contrast administration (intravenous versus intraarterial).     

Exact solution of the unidimensional Poisson-Boltzmann equation for a 1:2 (2:1) electrolyte

An endo-beta-N-acetyl glucosaminidase of rabbit serum has been characterized after purification by affinity chromatography. The specificity was determined by fluorimetric monitoring of the hydrolysis of 4-methylumbelliferyl-beta-glycosides and by thin layer chromatography identification of the hydrolysis products of fluoresceinyl-beta-glycosides. This enzyme acts on the following oligosaccharides GlcNac-beta-1-4 leads to GlcNAc-beta-O-R giving free di-N-acetyl chitobiose and R-OH as hydrolytic products.     

Murine leishmaniosis: a paradigm for the importance of T helper 1 and T helper 2 cells

The murine model of leishmaniosis is a prototypic example for the critical role played by T helper cells in immunity to pathogens. Cytokines, such as interleukin-12 and interleukin-4, are the major regulatory factors for differentiation of naive T helper cells into T helper 1 and T helper 2 cells, respectively. T helper 1 cells, which are cellular immune mechanisms involving gamma interferon production, are associated with protection against murine leishmaniosis. Loss of T helper 1 activity (i.e., reduced gamma interferon production and lack of macrophage activation) leads to a fatal progressive course of murine leishmaniosis. Knowledge of the murine model of leishmaniosis is now contributing to studies of infectious diseases in humans, livestock and companion animals. Greater insight into the pathogenesis, diagnosis and therapy of infectious diseases will be gained from the analysis of cytokine-dependent regulation of T helper responses during infection. In particular, the development of prophylactic and therapeutic vaccines will benefit significantly from these studies.     

Conversion of the major birch pollen allergen, Bet v 1, into two nonanaphylactic T cell epitope-containing fragments: candidates for a novel form of specific immunotherapy

A novel approach to reduce the anaphylactic activity of allergens is suggested. The strategy makes use of the presence of conformational immunoglobulin E (IgE) epitopes on one of the most common allergens. The three dimensional structure of the major birch pollen allergen, Bet v 1, was disrupted by expressing two parts of the Bet v 1 cDNA representing amino acids 1-74 and 75-160 in Escherichia coli. In contrast to the complete recombinant Bet v 1, the fragments showed almost no allergenicity and exhibited random coil conformation as analyzed by circular dichroism. Both nonanaphylactic fragments induced proliferation of human Bet v 1-specific T cell clones, indicating that they harbored all dominant T cell epitopes and therefore may be considered as a basis for the development of a safe and specific T cell immunotherapy.     

Evolution of the epidemic process as a form of solution to its internal contradictions

The author formulated the main contradition of the epidemic process consisting of contradiction between the interaction of the motive forces of the epidemic process, since this contradiction at the same time served as the imperative condition of the origination and as the cause of the subsequent arrest of the spread of infection. The main contradiction of the epidemic process is expressed in reduction of the number and limited activity of the sources of infection, attenuation or arrest of the mechanism of transmission of the causative agents, formation of immunity in the population, the appearance of hereditary resistance in the hosts to the causative agent of the infection. The action of the principal internal contradiction of the epidemic process in the course of evolution conditions genetic variability of the causative agents of the infectious diseases, intensification of the mechanisms of excretion of the parasites from the host organism, and increase of their resistance in the external environment, formation of latent forms of infection.     

一类散度型椭圆方程弱解的最大模估计

研究了散度型椭圆方程的弱解的性质。利用De Giorgi迭代技术做出了比Poisson方程稍一般的方程的弱解的最大模估计。     

Activated T helper 1 and T helper 2 cells differentially express the beta-2-adrenergic receptor: a mechanism for selective modulation of T helper 1 cell cytokine production

We recently reported that resting clones of murine Th1 cells, but not resting Th2 cells, expressed a detectable level of the beta-2-adrenergic receptor (beta 2AR). In the present study, we proposed that the level of beta 2AR expression on anti-CD3 mAb-activated CD4+ effector Th cells may differ from the level on resting cells, and that a change in receptor expression may alter the functional responsiveness of these cells to either the beta 2AR-selective ligand terbutaline or the sympathetic neurotransmitter norepinephrine. Following anti-CD3 activation, the beta 2AR was expressed on Th1 cells, but not Th2 cells. The number of binding sites on Th1 cells was maintained, with no change in affinity, over a 24-h activation period. When Th clones were exposed to terbutaline following anti-CD3 activation, Th1 cell, but not Th2 cell, cytokine production was modulated. IL-2 production by Th1 cells was decreased, while IFN-gamma production was not significantly altered. The decrease in IL-2 production was concentration dependent and was blocked by an antagonist. In comparison with control supernatants, the lower level of IL-2 present in terbutaline-exposed culture supernatants supported the proliferation of an IL-2-dependent Th1 clone to a lesser degree. Additionally, norepinephrine down-modulates IL-2, but not IFN-gamma, production by binding specifically to the beta-adrenergic receptor. Thus, a detectable level of the beta 2AR is expressed on activated Th1 cells, but not activated Th2 cells, thereby providing a mechanism by which IL-2 production is preferentially modulated by an endogenous and therapeutic ligand following Th1 cell activation.     

Improving MR quantification of regional blood volume with intravascular T1 contrast agents: accuracy, precision, and water exchange

The goal of this work was to develop a comprehensive understanding of the relationship between vascular proton exchange rates and the accuracy and precision of tissue blood volume estimates using intravascular T1 contrast agents. Using computer simulations, the effects of vascular proton exchange and experimental pulse sequence parameters on measurement accuracy were quantified. T1 and signal measurements made in a rat model implanted with R3230 mammary adenocarcinoma tumors demonstrated that the theoretical findings are biologically relevant; data demonstrated that over-simplified exchange models may result in measures of tumor, muscle, and liver blood volume fractions that depend on experimental parameters such as the vascular contrast concentration. As a solution to the measurement of blood volume in tissues with exchange that is unknown, methods that minimize exchange rate dependence were examined. Simulations that estimated both the accuracy and precision of such methods indicated that both the inversion recovery and the transverse-spoiled gradient echo methods using a "no-exchange" model provide the best trade-off between accuracy and precision.     

Metatarsophalangeal and intermetatarsal angle: different values and interpretation of postoperative results dependent on the technique of measurement

For measurement of the first metatarsophalangeal angle and intermetatarsal angle I-II, five different methods for drawing the axis of the first metatarsal have been published. This study aimed to evaluate differences in the resulting angles that depend on the method of drawing this axis. Using pre- and postoperative radiographs of 20 patients who had surgery on the hallux (chevron procedure), highly significant differences were found: mean values for the preoperative metatarsophalangeal angle ranged from 27.3 degrees to 31.9 degrees; the mean postoperative values were calculated at 8.6 degrees to 20.3 degrees. The preoperative mean of intermetatarsal angle I-II showed values from 13.0 degrees to 17.6 degrees; the postoperative mean ranged from 5.2 degrees to 16.7 degrees. These differences--especially in the postoperative evaluation--resulted in a postoperative improvement between 11.6 degrees and 20.8 degrees for the metatarsophalangeal angle and between 0.9 degrees and 10.0 degrees for the intermetatarsal angle. These wide differences seem to be unacceptable for angles as a criterion of success in surgery on the hallux. The reason for these discrepancies can be found in the different relations of the points of reference to the anatomical outline of the metatarsal and the site of osteotomy. As a consequence of this study, defining the axis of the first metatarsal as a line connecting the center of the articular surface of the metatarsal head and the center of the proximal articulation can be recommended as the most appropriate method. The resulting angles are independent of the type of surgery performed on the hallux.     

Use of an intravascular T1 contrast agent to improve MR cine myocardial-blood pool definition in man

The feasibility of improving myocardial/blood pool contrast in MR cine images through use of an intravascular contrast agent (Ferumoxtran, Advanced Magnetics, Inc., Cambridge, MA) was tested in four subjects. The contrast-to-noise ratio (CNR) demonstrated a trend toward improvement in the short axis and improved significantly in the long axis cine by an average of 128% (P < .05). Image intensity gradients at the myocardial/blood pool interface increased significantly in both the short and long axis (P < .01). It is expected that larger image intensity gradients at the endocardial border should improve the capabilities of automated segmentation algorithms, reducing the uncertainty and need for manual editing.