Intracellular mechanisms governing the acute phase of β-endorphin secretion from the corticotrope in vitro

It is not certain which protein kinase (A, C or both) is involved in the acute phase of β-endorphin (β-EP) release stimulated in the corticotrope by vasopressin (VP) and corticotropin-releasing factor (CRF). We have employed an isolated ovine anterior pituitary cell superfusion system to determine the dynamic effects of forskolin, a protein kinase A (PKA) stimulator, and phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator. Both secretagogues stimulated β-EP release within 5 min and therefore both PKA and PKC are potential mediators of the acute phase of hormonal stimulation of the corticotrope. Pretreatment with PMA specifically desensitized the pituitary cell columns to subsequent PMA exposure while not significantly altering sensitivity to forskolin or 50 mM KCl.     

Intergenic suppression of amber polynucleotide ligase mutation in bacteriophage T4. II

An intergenic suppressor (m) of the amber ligase mutation (amH39x) was isolated and a number of possible mechanisms of suppression were investigated. The intergenic suppressor does not appear to involve suppression of the amber codon. Biological tests and enzyme assays indicated that the intergenic suppressor mutation m is not associated with a nuclease defect. Complementation studies revealed incomplete dominance of both alleles (m or m⁺) of the suppressor gene, suggesting a noncatalytic function for the wild-type suppressor gene (m⁺). In a mixed infection of E. coli B with an amber ligase mutant and the intergenic suppressed strain the former was preferentially excluded. The m mutants are rapid lysis mutants but they differ from the rII mutants in a number of properties.     

Functional evidence of decreased tumorigenicity associated with monochromosome transfer of chromosome 14 in esophageal cancer and the mapping of tumor-suppressive regions to 14q32

Despite the abundant evidence of high allelic loss of chromosome arm 14q in human cancers, tumor-suppressor genes mapped to this chromosome have yet to be identified. To narrow the search for candidate genes, we performed monochromosome transfer of chromosome 14 into an esophageal carcinoma cell line, SLMT-1 S1. Statistically significant suppression of the tumorigenic potential of microcell hybrids containing the transferred chromosome 14 provided functional evidence that tumor-suppressive regions of chromosome 14 are essential for esophageal cancer. Tumor segregants emerging in nude mice during the tumorigenicity assay were analyzed by detailed PCR-microsatellite typing to identify critical nonrandomly eliminated regions (CRs). A 680-kb CR mapped to 14q32.13 and an approximately 2.2-Mb CR mapped to 14q32.33 were delineated. Dual-color BAC FISH analysis of microcell hybrids and tumor segregants verified the selective loss of the 14q32.13 region. In contrast, similar transfers of an intact chromosome 11 into SLMT-1 S1 did not significantly suppress tumor formation. These functional complementation studies showing the correlation of tumorigenic potential with critical regions of chromosome 14 validated the importance of the 14q32 region in tumor suppression in esophageal cancer. The present study also paved the path for further identification of novel tumor-suppressor genes that are relevant to the molecular pathogenesis of esophageal cancer.     

Selective decline in protein F1 phosphorylation in hippocampus of senescent rats

Certain forms of neuronal plasticity have been found to be expressed through alterations in brain protein phosphorylation, and its regulation by protein kinase activity. Of interest in this regard is the possibility that the decline in neuronal plasticity and cognitive function that occurs in advanced age may result in part from altered phosphorylation of specific proteins. As a first attempt to identify age-related changes in phosphoproteins, we assayed in vitro phosphorylation of proteins in hippocampus, cerebellum, entorhinal cortex, and frontal cortex from Fischer-344 rats of 5 months, 11 months, and 25 months of age. Compared to the middle-aged animals, the aged rats showed a selective 46% decline in phosphorylation of the 47 kDa protein (F1) in hippocampus, with no change in the phosphorylation of other proteins measured in this structure. Aged animals also showed decreased phosphorylation relative to young animals. No age-related change was observed in any protein band for the other brain areas examined. Since protein F1 is phosphorylated by protein kinase C (PKC), the cytosolic and membrane distribution of this enzyme was compared across age groups. The activity of PKC in hippocampus did not change across age. The explanation of this age-related decline in protein F1 phosphorylation is likely to be a decline in the substrate protein itself. The results are discussed in terms of protein F1's possible role in age-related decline of hippocampal synaptic plasticity.     

Enhancement of S-antigen and its mRNA in the irides of uveitic patients

S-antigen (S-Ag) and its mRNA were analysed by immunohistochemistry and in situ hybridization in 32 iridectomy specimens from 29 uveitic patients and 10 non-uveitic patients. S-Ag was detected in one iris and its mRNA was detected in 12 uveitic patients. Neither S-Ag nor its mRNA was found in the controls (P < 0.003). Ten of the 12 patients who had detectable S-Ag mRNA, while only four of the 17 patients who did not, had received corticosteroids for more than 3 years (P = 0.006). We also demonstrated S-Ag and its mRNA in bovine iris by immunoprecipitation and polymerase chain reaction. These results indicate that S-Ag and its mRNA accumulate in the irides of some uveitic patients. This accumulation may be the result of local immunoregulatory factors and an effect of corticosteroid treatment, and may modulate ocular inflammation.     

A retrospective review of visual outcome and complications in the treatment of retinoblastoma

The aim of this study was to look at the visual outcome and treatment complications of children diagnosed with Retinoblastoma during the years 1985-2003 inclusive. A retrospective review of all patients records was performed. Patient characteristics, treatment methods and complications were recorded. Twenty eight children presented to Temple street Hospital between 1985-2003. Six of these infants had bilateral tumours. The mean age at presentation was 23.7 months. Sixty-nine percent presented with Leucocoria, of these 33% also had a squint. The mean duration of symptoms was only known in 58% and this figure was approximately 19.8 months. Enucleation was performed in 24 eyes of 24 patients. Three patients required adjuvant chemotherapy post enucleation. Two eyes was treated with external beam radiation and one eye with plaque radiotherapy. One eye (second eye) was treated with systemic chemotherapy and radiation. Five eyes of three patients were treated with systemic chemotherapy followed by adjuvant Argon laser, cryotherapy and diode laser to each eye.The complications of each treatment group was recorded. The visual outcome in the salvaged eyes was favourable. There were no deaths recorded. Though chemotherapy with adjuvant local treatments provide adequate treatment for early tumours, enucleation still plays a major role in the treatment of Retinoblastoma. The total eye salvage rate in this study was 29% with an enucleation rate of 90% in unilateral cases and 33% in bilateral cases. Sixty-six percent of bilateral eyes affected were salvaged. Seventy-one percent of tumours were diagnosed after a parent noticed a gross abnormality of the eye. This highlights the possible need for screening for retinoblastoma in the infant population.     

Radioimmunoassay of detirelix ([ N-Ac-D-Nal(2)1,D-p-Cl-Phe2,D-Trp3, D-hArg(Et)6(2),D-Ala10]-luteinizing hormone-releasing hormone) in plasma or serum

A procedure for the radioimmunoassay (RIA) of detirelix in plasma or serum at concentrations as low as 0.15 ng/ml is described. Antiserum was produced by deacetylation of the N-terminus amino groups of detirelix and coupling this analog to bovine serum albumin with a carbodiimide and immunizing rabbits with the resultant conjugate. For RIA, 125I-labeled detirelix was used as the tracer and a double antibody procedure was used to separate the free and bound fractions. No purification of samples was required prior to RIA. Accuracy of the method was assessed by adding known quantities of detirelix to detirelix-free plasma and determining the ratio of measured to added analyte. Linear regression analysis for the concentration range 0.15-150.0 ng/ml yielded a regression equation of y = 0.88 X +1.46 and a correlation coefficient of 0.996. Additional validation was obtained from an in vivo study in which [14C]detirelix was administered to monkeys and plasma clearance profiles were determined by RIA and an HPLC-radiochemical method. The RIA results were in good agreement with those obtained by the HPLC method.     

Comparison of haemoglobin H inclusion bodies with embryonic zeta globin in screening for alpha thalassaemia.

AIMS--To compare the haemoglobin (Hb) H inclusion test with immunocytochemical detection of embryonic zeta chains in screening for alpha thalassaemia. METHODS--Blood samples from 115 patients with relevant clinical history and hypochromic microcytic indexes were screened using the HbH inclusion test and the Variant Hemoglobin Testing System (BioRad, Hercules, CA, USA). RESULTS--The HbH inclusion test was positive in 61 of 115 cases, three of whom had HbH disease confirmed by electrophoresis. The remaining 58 had alpha thalassaemia 1. All three HbH cases and 56 of 58 cases of alpha thalassaemia 1 expressed embryonic zeta chains, giving a specificity of 96.7%. Fifty four of 115 cases had a negative HbH inclusion test, of whom 50 had beta thalassaemia trait and three had iron deficiency. No diagnosis was reached for the remaining patient. CONCLUSION--The immunocytochemical test is as sensitive as the HbH inclusion test in screening for alpha thalassaemia. The presence of zeta chains is highly specific for alpha thalassaemia 1 incorporating the (--/SEA) deletion. The specificity and simplicity of the immunocytochemical test make it the test of choice in screening for alpha thalassaemia.     

Image reconstruction of anisotropic conductivity tensor distribution in MREIT: computer simulation study

We describe a novel method of reconstructing images of an anisotropic conductivity tensor distribution inside an electrically conducting subject in magnetic resonance electrical impedance tomography (MREIT). MREIT is a recent medical imaging technique combining electrical impedance tomography (EIT) and magnetic resonance imaging (MRI) to produce conductivity images with improved spatial resolution and accuracy. In MREIT, we inject electrical current into the subject through surface electrodes and measure the z-component Bz of the induced magnetic flux density using an MRI scanner. Here, we assume that z is the direction of the main magnetic field of the MRI scanner. Considering the fact that most biological tissues are known to have anisotropic conductivity values, the primary goal of MREIT should be the imaging of an anisotropic conductivity tensor distribution. However, up to now, all MREIT techniques have assumed an isotropic conductivity distribution in the image reconstruction problem to simplify the underlying mathematical theory. In this paper, we firstly formulate a new image reconstruction method of an anisotropic conductivity tensor distribution. We use the relationship between multiple injection currents and the corresponding induced Bz data. Simulation results show that the algorithm can successfully reconstruct images of anisotropic conductivity tensor distributions. While the results show the feasibility of the method, they also suggest a more careful design of data collection methods and data processing techniques compared with isotropic conductivity imaging.     

Rapid detection of Epstein-Barr virus DNA in clinical samples of oral hairy leukoplakia with HRP-labeled DNA probes and in situ hybridization.

An in situ hybridization technique, using horseradish peroxidase (HRP)-labeled DNA probes containing a portion of the Epstein-Barr virus (EBV) genome, was used to detect EBV DNA in tongue sections and smears from patients with oral lesions resembling the clinical features of oral hairy leukoplakia (HL). Eleven biopsy specimens (six consistent with HL, four normal tongue controls, and one leukoplakia) and 11 tongue smears were evaluated for the presence of EBV, cytomegalovirus (CMV), herpes simplex virus (HSV), and human papillomavirus (HPV) type 16. Following hybridization, six biopsy specimens and 10 tongue smears were found positive for EBV. All biopsy cases were negative for CMV, HSV, HPV-16 and the negative control probe. The specificity of the in situ hybridization assay was 100%. These results suggest that in situ hybridization using HRP-labeled DNA probes may be useful as a rapid diagnostic method for the detection of EBV in tongue sections or smears from patients diagnosed with HL.