Anomalies in hepatobiliary excretion of technetium-99m-MAG3 preparations

Technetium-99m-MAG3 is accepted as a renal tubular function agent. However, sporadic liver and gall bladder visualisation during its clinical use is clearly a disadvantage. HPLC-purified 99mTc-MAG3 samples exhibited appreciable hepatobiliary uptake (7%), and an elevated level of such uptake was observed in unpurified kit preparations, which was stated to be associated with the excretory property of the radiolabeled kit impurities. To verify this we attempted to quantitate the hepatobiliary uptake of the kit preparations with that of its radiolabeled components. The contribution of each component toward hepatobiliary uptake of the sample was calculated from their abundance in the chelate mixture and the individual biodistribution of the isolated components. However, the anticipated hepatobiliary uptake of different preparations of 99mTc-MAG3 calculated in this way was always lower than that of the experimental value determined directly. Further work is needed to explain the anomaly.     

Long-term effect of alkaline, organic acid, or hot water washes on the microbial profile of refrigerated beef contaminated with bacterial pathogens after washing

One hundred consecutive patients (81 male and 19 female) with unstable angina pectoris undergoing coronary angiography were divided according to Braunwald's clinical classification. Seventeen (17%) patients had new onset angina (class I), 68 (68%) sub-acute angina (class II) and 15 (15%) had acute rest angina (class III). Twenty-seven (27%) patients had secondary unstable angina pectoris (class A), 49 (49%) primary unstable angina (class B) and 24 (24%) had post-infarction unstable angina (class C). ST-T wave changes on ECG were present in 54 (54%) while absent in 46 (46%) patients. On coronary angiography, 26 (26%) patients had single vessel disease, 30 (30%) double vessel disease and 39 (39%) patients had triple vessel disease. Five (5%) patients were found to have normal coronaries. Classification of patients according to Braunwald's clinical classification showed single vessel disease to be higher in class I as compared to class II (47% vs 22%; p = 0.04) and classes III (47% vs 20%; p<0.01). Single vessel disease was found to be higher in class C as compared to class B (41.7% vs 16.4; p = 0.01). Double vessel disease was higher in class B as compared to class A (40.8% vs 18.5%, p = 0.04). Triple vessel disease incidence was not found to be significantly different among different clinical classes. Morphology of coronary artery lesions was classified according to Ambrose's classification. Out of the total of 248 lesions in the whole study group, there were 68 (27.42%) concentric lesions, 55 (22.18%) eccentric type I lesions, 23 (9.27%) eccentric type II lesions, 42 (16.94%) multiple irregularity lesions and 60 (24.19%) totally occluded lesions. Concentric lesions were found to be higher in class C as compared to class B (40% vs 19.8%; p = 0.014). Statistically significant difference was not present in the distribution of other morphological type of lesions among different clinical classes. In the whole study group, intra-luminal thrombus was found to be present in 17 (17%) of patients. Distribution of intra-luminal thrombus according to Braunwald's classification showed that none of the patients in class I had intra-luminal thrombus, while 13 (19.1%) patients in class II and 4(26.7%) in class III had intra-luminal thrombus. The difference in the occurrence of intra-luminal thrombus between class I and class II (p = 0.004) and class I and class III (p = 0 .03 was found to be significant. Thus, majority of patients undergoing coronary angiography had primary sub-acute rest angina. Single vessel disease was higher in new onset angina. Patients with unstable angina pectoris and ST-T changes on ECG had higher number of lesions per patient and higher eccentric type I lesions. Intra-luminal thrombus was more frequently encountered with acute rest angina. However, the distribution of different morphological type of lesions on coronary angiography did not differ significantly in different clinical classes of unstable angina pectoris divided according to Braunwald's classification.     

Organophosphorus hydrolase is a remarkably stable enzyme that unfolds through a homodimeric intermediate

Organophosphorus hydrolase (OPH, EC 8.1.3.1) is a homodimeric enzyme that catalyzes the hydrolysis of organophosphorus pesticides and nerve agents. We have analyzed the urea- and guanidinium chloride-induced equilibrium unfolding of OPH as monitored by far-ultraviolet circular dichroism and intrinsic tryptophan fluorescence. These spectral methods, which monitor primarily the disruption of protein secondary structure and tertiary structure, respectively, reveal biphasic unfolding transitions with evidence for an intermediate form of OPH. By investigating the protein concentration dependence of the unfolding curves, it is clear that the second transition involves dissociation of the monomeric polypeptide chains and that the intermediate is clearly dimeric. The dimeric intermediate form of OPH is devoid of enzymatic activity, yet clearly behaves as a partially folded, dimeric protein by gel filtration. Therefore, we propose an unfolding mechanism in which the native dimer converts to an inactive, well-populated dimeric intermediate which finally dissociates and completely unfolds to individual monomeric polypeptides. The denaturant-induced unfolding data are described well by a three-state mechanism with delta G for the interconversion between the native homodimer (N2) and the inactive dimeric intermediate (I2) of 4.3 kcal/mol while the overall standard state stability of the native homodimer relative to the unfolded monomers (2U) is more than 40 kcal/mol. Thus, OPH is a remarkably stable protein that folds through an inactive, dimeric intermediate and will serve as a good model system for investigating the energetics of protein association and folding in a system where we can clearly resolve these two steps.     

Effect of ICV infusion of CRF on blood pressure and adrenal steroids in rabbits

The effect of prolonged, 22 h long, intracerebroventricular (i.c.v.) infusion of corticotropin-releasing hormone (CRF) on plasma cortisol, corticosterone and electrolyte concentrations, mean arterial blood pressure (MAP) and heart rate (HR) were investigated in conscious rabbits. During i.c.v. infusion of CRF, 1 and 3 micrograms/h, at a rate of 17 microliters/h, plasma cortisol and corticosterone concentrations rose to the level noted after ACTH stimulation in rabbits. Plasma [Na] did not change, but plasma [K] was reduced and plasma osmolality increased during the infusion of CRF, 3 micrograms/h. MAP and HR, recorded continuously during i.c.v. infusion of CRF, changed only with the higher dose of CRF: MAP was elevated during the first 5 h of infusion, and then returned to the control level. HR was lower than control at the end of the first hour of infusion and again between 9 and 15 h of infusion. The prolonged rise of CRF concentration in the brain induced a sustained rise in circulating adrenal steroid hormones. MAP did not increase to the level noted after bolus i.c.v. injection of CRF and the rise in MAP was not sustained.     

Direct cardiac and vascular actions of adrenomedullin in conscious sheep

OBJECTIVE: Patients with Kawasaki disease mount an immune response directed to their abnormally stimulated vascular endothelium, that is associated with vascular inflammation and injury and a predisposition to arterial aneurysm formation. This suggests that specific pro-inflammatory cytokines may mediate these hyperreactive responses. The selective chemoattractant and activation effects of chemokines on lymphocytes identifies them as potential candidates in mediating selective inflammatory processes in Kawasaki disease. We examined peripheral blood from patients with Kawasaki disease for chemokine gene expression. METHODS: Consecutive samples from 14 patients during the acute, subacute, and convalescent phases of their illness were collected and elaborated for RANTES, macrophage inflammatory protein-1 beta (MIP-1 beta) and monocyte chemotactic protein-1 (MCP-1) expression. RESULTS: RANTES and MCP-1 gene expression levels were significantly elevated in 12 of the 14 patients, and MIP-1 beta gene expression was elevated in 13 of the 14 patients. There was no obvious correlation between clinical phase of the disease and chemokine expression level, yet elevated expression levels were detected in all phases, including the convalescent phase, when laboratory evidence of lymphocyte activation has been shown to return to normal. Serial samples showed persistence or increased expression of chemokine genes into the convalescent phase in patients with coronary artery lesions. CONCLUSION: Chemokine mediated inflammatory events may persist in the convalescent phase of Kawasaki disease and may contribute to further risk of vascular endothelial cell injury, specifically coronary aneurysm formation.     

Isolation of the PufX protein from Rhodobacter capsulatus and Rhodobacter sphaeroides: evidence for its interaction with the alpha-polypeptide of the core light-harvesting complex

Using mutant strains of Rhodobacter capsulatus and Rhodobacter sphaeroides in which the pufX gene had been deleted, it was possible to identify by HPLC membrane protein components present in pufX+ cells but absent in pufX- cells. In parallel preparations, membrane proteins soluble in chloroform/methanol containing ammonium acetate were first extracted from lyophilized membrane fractions of the pufX+ cells and separated from pigments and larger protein material by gel-filtration chromatography. Protein-containing fractions were examined by HPLC, and several peaks were collected from pufX+ material that were not present in pufX- material. From N-terminal amino acid sequencing, the PufX protein of Rb. capsulatus was identified, and from positive interaction with a PufX protein antibody, the Rb. sphaeroides PufX protein was identified. Although overall yields were very small, sufficient quantities of these proteins were isolated to evaluate their effect on the reconstitution of the core light-havesting antenna (LH1) and its subunit complex. From the behavior of the PufX protein and the alpha-polypeptide of LH1 on HPLC, qualitative evidence was obtained that the two proteins have a high affinity for each other. In reconstitution assays with bacteriochlorophyll (Bchl) and the LH1 alpha- and beta-polypeptides of Rb. capsulatus, the PufX protein of Rb. capsulatus was inhibitory to LH1 formation at low concentration. A similar inhibition was exhibited by Rb. sphaeroides PufX protein for reconstitution of LH1 with Bchl and the LH1 alpha- and beta-polypeptides of Rb. sphaeroides. In both cases, the ratios of concentrations of the PufX protein to the alpha-polypeptide causing 50% inhibition were approximately 0.5. Formation of the heterologous (alpha beta) subunit-type complex formed with Bchl and the alpha- and beta-polypeptides of LH1 of Rb. capsulatus was also inhibited by low concentrations of the Rb. capsulatus PufX protein (approximately 50% inhibition at PufX:alpha-polypeptide ratios = 0.5). However, neither PufX protein inhibited formation of a homologous (beta beta) subunit-type complex, which indicates that the PufX proteins do not interact with the beta-polypeptides.     

Prostate-specific antigen concentrations in serum in acute illnesses

In light of recent studies showing that prostate-specific antigen (PSA) complexes with certain blood proteins, we studied the effects of acute-phase reactants and alpha 2-macroglobulin (A2MG) on serum concentrations of PSA. Serum samples were obtained from 419 men admitted to an acute-care facility. Various acute-phase reactants-including C-reactive protein, alpha 1-acid glycoprotein, alpha 1-antitrypsin, and alpha 1-antichymotrypsin-and A2MG were measured with a Beckman Array analyzer in parallel with determinations of PSA concentrations by two methods, the Hybritech Tandem RIA and the Abbott PSA IMx. Evaluation by Spearman rank correlation revealed a significant negative correlation of A2MG with PSA values (P < 0.01) and (as expected) a positive correlation of age with PSA values (P < 0.001). The former correlation suggests the possibility that patients with high serum concentrations of A2MG may give falsely decreased results for PSA concentrations in serum.     

Bacterial profile of ground beef made from carcass tissue experimentally contaminated with pathogenic and spoilage bacteria before being washed with hot water, alkaline solution, or organic acid and then stored at 4 or 12 degrees C

The genes of the myc/max/mad family play an important role in controlling cell proliferation and differentiation. We have identified the first homologues of the mad and max genes in the nematode C. elegans, which we have named mdl-1 and mxl-1 respectively. Like the vertebrate MAD proteins, MDL-1 binds an E-box DNA sequence (CACGTG) when dimerized with MXL-1. However, unlike vertebrate MAX, MXL-1 can not form homodimers and bind to DNA alone. Promoter fusions to a GFP reporter suggest that these genes are coexpressed in posterior intestinal and post-mitotic neuronal cells during larval development. The coexpression in the posterior intestinal cells occurs before their final division at the end of the L1 stage and persists afterwards, demonstrating that mad and max expression can be correlated directly to the cell cycle state of an individual cell type. These data also show that mxl-1 is an obligate partner for mdl-1 in vivo and in vitro and indicate that these genes may play an important role in post-embryonic development. Finally, MDL-1 can suppress activated c-MYC/RAS-induced focus formation in a rat embryo fibroblast transformation assay. Like the vertebrate MAD protein, MDL-1 activity in suppressing transformation is dependent on a functional SIN3 interaction domain.