Characterisation of the enzymatic 4-O-acetylation of sialic acids in microsomes from equine submandibular glands

Microsomes prepared from equine submandibular glands and incubated with tritium-labelled AcCoA incorporated acid-insoluble radioactivity in a manner dependent on time, protein, membrane integrity and AcCoA concentration, with incorporation being optimal at 37 degrees C and pH 6.6. Under the experimental conditions used a K(M) of 32.1 microM for AcCoA and a V(max) of 1.2 pmol/mg protein x min was obtained. The incorporation of acid-insoluble radioactivity was also inhibited by CoA in a competitive manner (K(i)=240 microM), as well as by para-chloromercuribenzoate, 3'-dephospho-CoA, 5'-IDP, 5'-ADP, beta-NAD and 4,4'-diisothiocyanatostilbene-2,2'-disulfonate. We demonstrate here that this incorporation of radioactivity into endogenous sialic acid is due to the action of an AcCoA:sialate-4-O-acetyltransferase [EC 2.3.1.44]. Radio thin-layer chromatography analyses of propionic acid-released sialic acids showed that the incorporation of radioactivity correlated with the formation of a radiolabelled species that co-migrated with authentic Neu4,5Ac2. Saponification experiments using NaOH, mouse hepatitis virus strain S and Influenza C/JJ/50 virus also showed that the transfer of [3H]acetyl groups from [3H]AcCoA to endogenous sialic acid acceptors was occurring exclusively at carbon 4 of the pyranose ring.

Pure primary choriocarcinoma of the urinary bladder with long-term survival

Choriocarcinoma was diagnosed in a 77-year-old woman with an acute massive, painless hematuria. One year after anterior pelvic exenteration and ileal conduit, the beta-human chorionic gonadotropin level increased to 934 mIU/mL without any sign of tumor progression. After six courses of chemotherapy (vincristine, actinomycin, and cyclophosphamide), the beta-human chorionic gonadotropin levels returned to normal. To our knowledge, this is the fourth case of pure choriocarcinoma in the bladder, with the longest survival time of 33 months so far.

Degradation mechanism and stability of 5-aminolevulinic acid

The physiological substance and precursor of the heme synthesis 5-aminolevulinic acid (ALA) is a promising prodrug for photodiagnosis and photodynamic therapy of epithelial tumors, particularly in urological and gynecological tissues. For the clinical use of this substance, a chemically stable and sterile drug formulation is required. In the present study, degradation mechanism of ALA in aqueous solution and possibilities to improve its stability were examined. A capillary electrophoretic method was developed that was suitable for the quantification of ALA and of two degradation products. The intermediate degradation product was 2, 5-dicarboxyethyl-3,6-dihydropyrazine, which was further oxidized to 2,5-dicarboxyethylpyrazine. The structures of the degradation products were proven by (1)H and (13)C nuclear magnetic resonance spectroscopy. ALA degradation was very efficiently inhibited by adjusting the pH of the aqueous solution to a value <5 and by purging with nitrogen. Additives such as antioxidants did not improve the ALA stability. These results demonstrated that low pH ALA aqueous solution may be one possible dosage form to be considered for market introduction.

[Accidental morbidity in adolescence: a retrospective study in 12 to 15 year-old school children in Switzerland]

Mortality and morbidity from injuries in the adolescent population is substantial in Switzerland as all over the world. The estimation of morbidity from injuries is difficult and depends on the design of the study. Little information is available on morbidity between ages 12 and 15. The Health Behaviour in School-Aged Children (HBSC) study is an international survey based on a self-administered questionnaire for which the Swiss Institute for Prevention of Alcohol and Drug Problems (SIPA) is responsible in Switzerland. 7196 schoolchildren aged 12 to 15 participated in the 1998 survey. Questions covered subjects such as health and health behaviour. A few questions covered injuries, with reference to frequency, context and consequences. 45.3% of adolescents have been treated at least once by a nurse or a doctor for an injury during the past 12 months. It can be deduced that nearly 149,000 adolescents aged between 12 and 15 are injured in more than 260,000 accidents in Switzerland. The rate of injury is 793 per 1000 adolescents per year. Furthermore, one adolescent out of ten injures himself three times or more per year. In conclusion, morbidity due to injuries in adolescents aged 12 to 15 in Switzerland is therefore considerable. This study demonstrates the high prevalence of repeated injuries in adolescents.

Validation of a capillary electrophoresis method for determination of 5-aminolevulinic acid and degradation products

A capillary electrophoresis method was developed for simultaneous quantification of 5-aminolevulinic acid (ALA) and its degradation products 2,5-dicarboxyethyl-3,6-dihydropyrazine and 2,5-dicarboxyethylpyrazine in aqueous solution within a total analysis time of 9 min. The optimized method was validated with respect to specificity, precision, linearity, limits of detection and quantitation, and robustness. The degradation products were quantified with respect to the ALA peak. A related micellar electrokinetic chromatography method, involving the addition of sodium dodecylsulfate to the running buffer solution, was applied for direct injection of an oil-in-water emulsion containing ALA, i.e. without sample pretreatment.

Incidentally discovered papillary carcinoma of the thyroid: value of ultrasonographic follow-up. A case-report

Incidentalomas of the thyroid are common small nodules found occasionally during imaging procedures. Their pathological nature is generally benign, but about 4% may harbour malignant tissue. Most current studies only suggest clinical follow-up, but there are no data about the natural history of malignant incidentalomas. The authors describe a patient with multiple incidentaloma of the thyroid submitted to fine-needle aspiration biopsy because his larger nodule grew 50% in 3 months at ultrasonographic follow-up. The cytological examination suggested thyroid malignancy in this nodule and surgical pathology showed multicentric papillary carcinoma. This case suggests that the larger diameter of a malignant incidentaloma may change rapidly. If more time had been spent before repeating the ultrasonography, the volume could have changed even more and the prognosis could have been changed as indicated by most prognostic score indexes.

A method for the chemical generation of N-terminal peptide sequence tags for rapid protein identification

We describe a method for generating multiple small sequences from the N terminal of peptides in unseparated protein digests by stepwise thioacetylation and acid cleavage. The mass differences between a series of N-terminally degraded peptides give short sequences of defined length. Such short "sequence tags" together with the mass of the parent peptide can be used to identify the protein in a database. The sequence ladders are generated without the use of chain terminators or sample aliquoting and the degradation reagents are water soluble so that the chemistry can be carried out on peptides immobilized on C-18 reversed-phase supports without any peptide loss due to washing with organic solvents as occurs in Edman type sequencing. The entire procedure can be automated, and we describe a prototype device for the parallel analysis of multiple samples. We demonstrate the effectiveness of this chemical tagging method in a comparison with Edman sequencing, peptide mass fingerprinting, and MS/MS analysis of crude protein fractions obtained from an HPLC separation of the Escherichia coli ribosome complex which consists of 57 proteins. We show that chemical tagging is a viable first-pass high-throughput identification method to be used prior to an in depth MS/MS analysis.

Localization of S-adenosylhomocysteine hydrolase in the rat kidney

S-adenosylhomocysteine (SAH) hydrolase is a cytosolic enzyme present in the kidney. Enzyme activities of SAH hydrolase were measured in the kidney in isolated glomeruli and tubules. SAH hydrolase activity was 0.62 +/- 0.02 mU/mg in the kidney, 0.32 +/- 0.03 mU/mg in the glomeruli, and 0.50 +/- 0.02 mU/mg in isolated tubules. Using immunohistochemical methods, we describe the localization of the enzyme SAH hydrolase in rat kidney with a highly specific antibody raised in rabbits against purified SAH hydrolase from bovine kidney. This antibody crossreacts to almost the same extent with the SAH hydrolase from different species such as rat, pig, and human. Using light microscopy, SAH hydrolase was visualized by the biotin-streptavidin-alkaline phosphatase immunohistochemical procedure. SAH hydrolase immunostaining was observed in glomeruli and in the epithelium of the proximal and distal tubules. The collecting ducts of the cortex and medulla were homogeneously stained. By using double immunofluorescence staining and two-channel immunofluorescence confocal laser scanning microscopy, we differentiated the glomerular cells (endothelium, mesangium, podocytes) and found intensive staining of podocytes. Our results show that the enzyme SAH hydrolase is found ubiquitously in the rat kidney. The prominent staining of SAH hydrolase in the podocytes may reflect high rates of transmethylation. (J Histochem Cytochem 48:211-218, 2000)

Hormonal therapy of prostate cancer: is there any news?

Androgen ablative therapy was introduced in the early 1940s and, even today, has remained the golden standard for the treatment of advanced prostate cancer. During the past decades, a variety of improvements have been achieved which, however, primarily aimed at a better tolerance or improved acceptance of androgen deprivation. However, after almost six decades of hormonal therapy it is appropriate to ask whether progress was also made in terms of efficacy, particularly as far as prolongation of survival or quality of life is concerned. During the last few years, two therapeutic strategies, maximal androgen blockade and intermittent androgen suppression, have been considered true conceptual advances. However, despite tremendous efforts and a huge number of studies so far, these concepts appear to produce more questions rather than answers. Therefore, it seems appropriate to raise some critical issues of maximal androgen blockade and intermittent androgen suppression.

Operative therapy in disease progression and local recurrence of renal cell carcinoma

When local recurrence or distant metastasis occurs, the question arises as to which therapeutic concept should be applied. In contrast to the data on systemic immunotherapy, there are no systematic studies on surgical management of metastasis. Local recurrence (a rare condition) is frequently resected, whereby a prolongation of life can be achieved in individual cases. The complete surgical resection of pulmonary metastases has been shown, in a number of studies, to achieve a survival rate of 5 years in up to 44% of the cases. There are only few data regarding resection of osseous metastases; although in this respect some studies have reported an average survival rate of 34 months, the indication for this condition has, up to now, usually been seen as palliative. The prognosis of liver or brain metastasis is unfavorable; the survival rates achieved with the help of surgical procedures are scarcely higher than those resulting from the spontaneous progression of metastatic renal carcinoma (12 months). Thus, there is an urgent need for further studies in order to define the indication for the surgical management of metastasis.

Diagnosis and staging of prostatic carcinoma: what is really necessary?

Diagnosis and staging of prostatic carcinoma should be considered in men in whom treatment with curative intent is possible. The primary tools for detection of cancer are digital rectal examination (DRE) and serum prostate-specific antigen (PSA), whereas transrectal ultrasonography is best used to guide the needle for biopsy. Staging should be based on the TNM system. The most reliable staging methods include a combination of DRE, PSA and systematic biopsies for local tumor extension, pelvic lymphadenectomy for regional lymph nodes, and PSA and bone scintigraphy for distant metastases. Computed tomography and magnetic resonance imaging are not necessary in most cases.

Serine/threonine phosphorylation of calmodulin modulates its interaction with the binding domains of target enzymes

The interaction of serine/threonine-phosphorylated calmodulin with synthetic peptides corresponding to the calmodulin-binding domains of six enzymes has been studied by fluorescence spectroscopy. For five peptides, the dissociation constant of the calmodulin-peptide complex (K(d)) increased when calmodulin was phosphorylated. An increase of more than one order of magnitude was observed with peptides derived from smooth-muscle myosin light-chain kinase and cAMP phosphodiesterase. In contrast, only a slight increase in K(d) was noted with two peptides derived from the plasma membrane Ca(2+)-ATPase and for the peptide derived from nitric oxide synthase. No significant change in affinity was detected with the peptide derived from calcineurin. In contrast, a decrease in the dissociation constant was observed with the peptide derived from the Ca(2+)-calmodulin dependent kinase II. Phosphorylation also affected the peptide-calmodulin binding stoichiometry: a decrease from two to one binding sites was observed with the peptides derived from myosin light-chain kinase and phosphodiesterase.

Pharmaco-toxicological mode of action of antimicrobial 5-nitroimidazole derivatives

5-Nitroimidazole derivatives are used as therapeutic agents against anaerobic microorganisms which are pathogenic to man and animals. The antimicrobial mode of action of these compounds is due to the metabolic reduction of the nitro group by microbial metabolism. By analogy, a reduction of the 5-nitro group in the aerobic animal metabolism is commonly assumed. This assumption is doubtful in its general form, and a more differentiated view is presented.

NMR solution structure of a complex of calmodulin with a binding peptide of the Ca2+ pump

The three-dimensional structure of the complex between calmodulin (CaM) and a peptide corresponding to the N-terminal portion of the CaM-binding domain of the plasma membrane calcium pump, the peptide C20W, has been solved by heteronuclear three-dimensional nuclear magnetic resonance (NMR) spectroscopy. The structure calculation is based on a total of 1808 intramolecular NOEs and 49 intermolecular NOEs between the peptide C20W and calmodulin from heteronuclear-filtered NOESY spectra and a half-filtered experiment, respectively. Chemical shift differences between free Ca(2+)-saturated CaM and its complex with C20W as well as the structure calculation reveal that C20W binds solely to the C-terminal half of CaM. In addition, comparison of the methyl resonances of the nine assigned methionine residues of free Ca(2+)-saturated CaM with those of the CaM/C20W complex revealed a significant difference between the N-terminal and the C-terminal domain; i.e., resonances in the N-terminal domain of the complex were much more similar to those reported for free CaM in contrast to those in the C-terminal half which were significantly different not only from the resonances of free CaM but also from those reported for the CaM/M13 complex. As a consequence, the global structure of the CaM/C20W complex is unusual, i.e., different from other peptide calmodulin complexes, since we find no indication for a collapsed structure. The fine modulation in the peptide protein interface shows a number of differences to the CaM/M13 complex studied by Ikura et al. [Ikura, M., Clore, G. M., Gronenborn, A. M., Zhu, G., Klee, C. B., and Bax, A. (1992) Science 256, 632-638]. The unusual binding mode to only the C-terminal half of CaM is in agreement with the biochemical observation that the calcium pump can be activated by the C-terminal half of CaM alone [Guerini, D., Krebs, J., and Carafoli, E. (1984) J. Biol. Chem. 259, 15172-15177].

CDKN2A (P16(INK4a)) and CDK4 mutation analysis in 131 Australian melanoma probands: effect of family history and multiple primary melanomas

Mutation analysis of two genes involved in melanoma susceptibility (CDKN2A/p16(INK4a) and CDK4) was undertaken in 131 probands with a family history of melanoma. Screening of all three exons of CDKN2A and exon 2 of CDK4 by single-strand conformation polymorphism (SSCP) analysis and/or direct sequencing identified a total of 10 different CDKN2A germline mutations, including 6 not previously described in the germline. All but one has been previously proven to, or is likely to, affect the structure and function of p16(INK4a). The incidence of CDKN2A mutation was 8.4% (11/131), but was significantly higher in families with three or more cases of melanoma (10/66, 15.1%) than in those in which only two relatives were affected (1/65, 1.5%). The incidence of CDKN2A mutation was also higher in families with three or more cases of melanoma and at least one member with multiple primary melanomas (6/19, 31.6%) than in similar families without multiple primary melanomas (4/47, 8.5%). One novel CDK4 variant of uncertain significance was found in a kindred that also carries a CDKN2A mutation. Genes Chromosomes Cancer 25:339-348, 1999.

A rapid method to separate endosomes from lysosomal contents using differential centrifugation and hypotonic lysis of lysosomes

Here we describe a fast and efficient subcellular fractionation procedure that permits lysosomes to be separated from endosomes. Differential centrifugation is used to isolate a subcellular fraction containing both endosomes and lysosomes. Because lysosomes are sensitive to osmotic stress, hypotonic conditions destroy them, whereas endosomes, which are osmotically insensitive, stay intact. We demonstrate that hypotonic lysis of an endosome-lysosome-pool releases 85% of the lysosomes into the supernatant as measured by the activity of the lysosomal marker enzyme N-acetyl-beta-D-glucosaminidase (beta-AGA). The endosomal fraction is thoroughly characterised using a variety of subcellular markers. After pulsing cells with fluorescein isothiocyanate labelled transferrin (FITC-Tf), only about 12% of the marker is released under hypotonic conditions. A typical fractionation procedure takes about 1-2 h from initial cell homogenisation. The fractionation gives a pure lysosomal fraction (fraction L) containing high activities of lysosomal enzymes and an endosomal fraction (fraction E) reflecting different stages of endosomes.

Tyrosine phosphorylation modulates the interaction of calmodulin with its target proteins

The activation of six target enzymes by calmodulin phosphorylated on Tyr99 (PCaM) and the binding affinities of their respective calmodulin binding domains were tested. The six enzymes were: myosin light chain kinase (MLCK), 3'-5'-cyclic nucleotide phosphodiesterase (PDE), plasma membrane (PM) Ca2+-ATPase, Ca2+-CaM dependent protein phosphatase 2B (calcineurin), neuronal nitric oxide synthase (NOS) and type II Ca2+-calmodulin dependent protein kinase (CaM kinase II). In general, tyrosine phosphorylation led to an increase in the activatory properties of calmodulin (CaM). For plasma membrane (PM) Ca2+-ATPase, PDE and CaM kinase II, the primary effect was a decrease in the concentration at which half maximal velocity was attained (Kact). In contrast, for calcineurin and NOS phosphorylation of CaM significantly increased the Vmax. For MLCK, however, neither Vmax nor Kact were affected by tyrosine phosphorylation. Direct determination by fluorescence techniques of the dissociation constants with synthetic peptides corresponding to the CaM-binding domain of the six analysed enzymes revealed that phosphorylation of Tyr99 on CaM generally increased its affinity for the peptides.

The hemagglutinin-esterase of mouse hepatitis virus strain S is a sialate-4-O-acetylesterase

By comparative analysis of the hemagglutinin-esterase (HE) protein of mouse hepatitis virus strain S (MHV-S) and the HE protein of influenza C virus, we found major differences in substrate specificities. In striking contrast to the influenza C virus enzyme, the MHV-S esterase was unable to release acetate from bovine submandibulary gland mucin. Furthermore, MHV-S could not remove influenza C virus receptors from erythrocytes. Analysis with free sialic acid derivatives revealed that the MHV-S HE protein specifically de-O-acetylates 5-N-acetyl-4-O-acetyl sialic acid (Neu4, 5Ac2) but not 5-N-acetyl-9-O-acetyl sialic acid (Neu5,9Ac2), which is the major substrate for esterases of influenza C virus and bovine coronaviruses. In addition, the MHV-S esterase converted glycosidically bound Neu4,5Ac2 of guinea pig serum glycoproteins to Neu5Ac. By expression of the MHV esterase with recombinant vaccinia virus and incubation with guinea pig serum, we demonstrated that the viral HE possesses sialate-4-O-acetylesterase activity. In addition to observed enzymatic activity, MHV-S exhibited affinity to guinea pig and horse serum glycoproteins. Binding required sialate-4-O-acetyl groups and was abolished by chemical de-O-acetylation. Since Neu4,5Ac2 has not been identified in mice, the nature of potential substrates and/or secondary receptors for MHV-S in the natural host remains to be determined. The esterase of MHV-S is the first example of a viral enzyme with high specificity and affinity toward 4-O-acetylated sialic acids.

Administrative behavior of directors in hospitals: the Israeli case

This article presents research findings on the behavior of directors in hospitals in Israel. According to the findings, hospital directors devote most of their time to internal organization processes and less time to the management of the external organizational environment. The findings also reveal that the orientation of these directors is toward centralization of authority and concentration of the decision-making process.

Heterogeneous cardiac sympathetic denervation and decreased myocardial nerve growth factor in streptozotocin-induced diabetic rats: implications for cardiac sympathetic dysinnervation complicating diabetes

Heterogeneous myocardial sympathetic denervation complicating diabetes has been invoked as a factor contributing to sudden unexplained cardiac death. In subjects with diabetic autonomic neuropathy (DAN), distal left ventricular (LV) denervation contrasts with preservation of islands of proximal innervation, which exhibit impaired vascular responsiveness. The aims of this study were to determine whether this heterogeneous pattern of myocardial sympathetic denervation occurs in a rat model of diabetes and to explore a potential association with regional fluctuations in myocardial nerve growth factor (NGF) protein. Myocardial sympathetic denervation was characterized scintigraphically using the sympathetic neurotransmitter analog C-11 hydroxyephedrine ([11C]HED) and compared with regional changes in myocardial NGF protein abundance and norepinephrine content after 6 and 9 months in nondiabetic (ND) and streptozotocin-induced diabetic (STZ-D) rats. In ND rats, no difference in [11C]HED retention or norepinephrine content was detected in the proximal versus distal myocardium. After 6 months, compared with ND rats, myocardial [11C]HED retention had declined in the proximal segments of STZ-D rats by only 9% (NS) compared with a 33% decrease in the distal myocardium (P < 0.05). Myocardial norepinephrine content was similar in both ND and STZ-D rats. At 6 months, LV myocardial NGF protein content in STZ-D rats decreased by 52% in the proximal myocardial segments (P < 0.01 vs. ND rats) and by 82% distally (P < 0.01 vs. ND rats, P < 0.05 vs. proximal segments). By 9 months, [11C]HED retention had declined in both the proximal and distal myocardial segments of the STZ-D rats by 42% (P < 0.01 vs. ND rats), and LV norepinephrine content and NGF protein were decreased in parallel. Therefore, 6 months of STZ-induced diabetes results in heterogeneous cardiac sympathetic denervation in the rat, with maximal denervation occurring distally, and is associated with a proximal-to-distal gradient of LV NGF protein depletion. It is tempting to speculate that regional fluctuations of NGF protein in the diabetic myocardium contribute to heterogeneous cardiac sympathetic denervation complicating diabetes.