bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of mental alerting on gaze‐evoked nystagmus
Authors: Humphriss R.L. , Morgan K.F.L. , Baguley D.M.
Published: March 2005

Objectives:  To determine whether mental alerting (MA) makes a significant difference to nystagmus recorded during gaze testing using electronystagmography (ENG).

Design:  A prospective study, blinded interpretation of test results, alternate order of testing sequence.

Setting:  Vestibular assessment clinic in a tertiary referral centre.

Participants:  A total of 80 patients were seen by the authors (R.L.H., K.F.L.M.) for vestibular assessment, between August 2002 and February 2004. Patients cognitively unable to perform MA tasks or with limited English were omitted. Patients all underwent gaze‐testing using ENG. Each patient was tested twice, once without MA and once with an MA task, in an alternate test order.

Main outcome measures:  Slow‐phase velocity values of recorded nystagmus, number of patients with clinically significant nystagmus (slow‐phase velocity ≥6 deg/s).

Results:  A total of eight patients had significant gaze‐evoked nystagmus when tested without MA and a total of six patients when tested with MA. Only four of these patients were common to both groups. When all nystagmus values (regardless of significance) were considered, no statistically significant differences between nystagmus measured with and without alerting were found (Wilcoxon signed rank test, P > 0.05).

Conclusions:  Mental alerting during gaze testing did not result in a significant difference in nystagmus and is just as likely to result in an exacerbation as a reduction in slow‐phase velocity. In addition, MA is likely to result in a noisy (and therefore difficult to interpret) recording and increases the impact of the test on the patient. In view of these findings, we propose that MA is contraindicated during the gaze‐testing component of the vestibular test battery.
Superior canal dehiscence: review of a new condition
Authors: Banerjee A. , Whyte A. , Atlas M.D.
Published: March 2005

Keypoints

•  A new cause of sound and pressure induced vertigo, superior canal dehisence, is described.

•  Auditory manifestations include hyperacusis to bone‐conducted sounds and conductive hearing loss with normal acoustic reflexes.

•  The diagnosis is reached by a directed history, documentation of upward and torsional nystagmus evoked by sound and pressure, and radiology.

•  Acoustic reflexes and VEMP (vestibular evoked myogenic potentials) aid in the identification of patients with an apparent conductive loss with normal acoustic reflexes or have an asymptomatic dehiscense on radiology.

•  Treatment involves avoidance of the precipitating stimuli. Surgical treatment, by resurfacing the dehiscence, is considered in patients with more severe symptoms.
How we do it: Radiofrequency‐turbinectomy for nasal obstruction symptoms
Authors: Harsten G.
Published: March 2005

Keypoints

•  Radiofrequency energy has been reported to be effective to reduce nasal obstruction because of inferior turbinate hypertrophy.

•  A total of 158 patients who had undergone such surgery are reported.

•  Three to 30 months postoperatively 85% of the patients reported a marked decrease in nasal obstruction. This was irrespective of a short‐term or a long‐term follow‐up, and was applicable to patients that had septal deviations in addition.

•  Radiofrequency‐turbinectomy is a simple and effective method for treatment of nasal obstruction as a result of hypertrophy of the inferior turbinates, even if combined with a moderate septal deviation.
Enhancement of long‐term testosterone secretion and steroidogenic enzyme expression in human Leydig cells by co‐culture with human Sertoli cell‐enriched preparations
Authors: LEJEUNE H. , SANCHEZ P. , SAEZ J. M.
Published: March 2005

We have shown previously that long‐term testosterone secretion, which decreases when human Leydig cells are cultured alone, increases when purified human Leydig and Sertoli cells are cultured together. In this work, human Leydig cell functions were studied further during in vitro culture, either alone or with human Sertoli cells, on a basal membrane derived from bovine corneal endothelial cells. The secretion of testosterone increased during the first week of co‐culture and remained elevated up to day 12 of culture. In one prolonged co‐culture, testosterone secretion decreased progressively after day 12 and, after 1 month of culture, was at a level similar to that observed during the first 48 h. After culture for 48 h, testosterone secretion in the co‐culture was enhanced by 162 ± 5% ( p < 0.0001) compared with values observed when Leydig cells were cultured alone (42.6 ± 10.6 ng/106 Leydig cells/48 h; mean ± SEM). This change was associated with increase in mRNA levels for 3β‐hydroxysteroid dehydrogenase Δ5–Δ4‐isomerase (2.49 ± 0.58‐fold), cytochrome P450c17 (2.81 ± 0.99‐fold), cytochrome P450scc (5.20 ± 0.13‐fold) and cytochrome P450 aromatase (1.73 ± 0.21‐fold) when Leydig cells were co‐cultured with Sertoli cells ( p < 0.05 for each enzyme). IGF‐I mRNA levels were higher (2.77 ± 0.72‐fold for 7.6 kb and 1.41 ± 0.07‐fold for 1.1–1.3 kb transcripts) in the Leydig–Sertoli cell co‐cultures than the sum of the levels in Leydig and in Sertoli cells cultured alone. Both basal and hCG‐induced testosterone secretion were enhanced by treatment of the co‐culture with human recombinant FSH (50mIU/mL). For basal testosterone secretion, this increase amounted to 163 ± 5% compared with Leydig cells cultured alone ( p < 0.0001) and by 112 ± 4% compared with non‐FSH treated co‐cultures ( p < 0.01); for hCG‐stimulated testosterone secretion this increase was 220 ± 12% compared with Leydig cells cultured alone ( p < 0.0001) and 132 ± 8% compared with non‐FSH treated co‐cultures ( p < 0.01). This study confirms the enhancement of long‐term testosterone secretion by adult human Leydig cells by co‐culture with adult human Sertoli cells and shows that this effect is associated with an enhancement of the expression of several steroidogenic enzymes; it might be mediated, as in other species, through increased production of IGF‐I by co‐culture.
The possible role of anaerobic bacteria in chronic prostatitis
Authors: SZÖKE I. , TÖRÖK L. , DÓSA E. , NAGY E. , SCULTÉTY S.
Published: March 2005

Prostatitis, the most common urological disease in men, afflicts between 25 and 50% of all adult men. Four clinical categories are recognized: acute and chronic bacterial prostatitis, non‐bacterial prostatitis and prostatodynia. The role of Gram‐positive aerobic bacteria and the different anaerobes in chronic bacterial prostatitis is still a matter of debate. During this study, the urethral discharge and the prostatic fluid obtained after prostatic massage of 50 patients with chronic prostatitis, confirmed by clinical examination and resistant to empirical quinolone therapy, were cultured under aerobic and anaerobic conditions. The parallel specimens from 24 patients exhibited high colony counts of Gram‐positive and Gram‐negative anaerobic bacteria, either alone (18 cases) or in combination with aerobic bacteria (6 cases). The specimens obtained after prostatic massage of the remaining 26 patients were completely negative for both aerobic and anaerobic bacteria. No Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum or Trichomonas vaginalis were isolated from these patients. Patients with chronic prostatitis who gave positive culture results for anaerobes were treated with amoxicillin/clavulanic acid or clindamycin for 3–6 weeks. After treatment, samples were again taken and cultured for all pathogens known to cause prostatitis. These post‐therapeutic samples revealed a decrease or total elimination of the symptoms, and no anaerobic bacteria could be detected.
White blood cells cause oxidative damage to the fatty acid composition of phospholipids of human spermatozoa
Authors: ZALATA A. A. , CHRISTOPHE A. B. , DEPUYDT C. E. , SCHOONJANS F. , COMHAIRE F. H.
Published: March 2005

The lipid composition of the sperm membrane has been shown to exert a significant effect upon the functional quality of spermatozoa. We have studied the effect of induced peroxidation and of the presence of polymorphonuclear white blood cells (WBCs) on the fatty acid composition of the phospholipids of human spermatozoa. The spermatozoa were fractionated by a discontinuous Percoll gradient in two fractions (47% and 90% Percoll). Induced peroxidation of spermatozoa was assessed by determining the production of thiobarbituric acid reactive substances (TBARS), mostly malondialdehyde, after incubation with ferrous sulphate and sodium ascorbate as a promoter of peroxidation. TBARS production after induction of peroxidation was correlated with the abundance of polyunsaturated fatty acids (PUFA) (r = 0.68, p < 0.0001), with the double bond index (r = 0.72, p < 0.0001), and with the oxidative potential index (r = 0.73, p < 0.0001) of fatty acids of phospholipids. In comparison with samples containing > 1 × 106 WBCs/mL, those with < 1 × 106 WBCs/mL contained higher proportions of PUFA (90% Percoll, p < 0.05; 47% Percoll, p < 0.05), total ω3 fatty acids (90% Percoll, p < 0.05; 47% Percoll, p < 0.001), docosahexaenoic acid (90% Percoll p < 0.05; 47% Percoll, p < 0.05), and double bond index (90% Percoll, p < 0.05; 47% Percoll, p < 0.001). In addition, mean melting point was significantly lower (90% Percoll, p < 0.05; 47% Percoll, p < 0.001) in samples with < 1 × 106 WBCs, indicating higher membrane fluidity. The increase of TBARS production by spermatozoa after incubation with the xanthine–xanthine oxidase system and/or ferrous sulphate as promoter of peroxidation was associated with a significant decrease of PUFA. Incubation of spermatozoa with WBCs, with or without activation by phorbol ester, decreased the PUFA ( p < 0.05). Also, TBARS production was increased ( p < 0.01) after activation of WBCs with phorbol ester.  Our data provide evidence that oxidative stress induced by WBCs has a damaging effect on the polyunsaturated fatty acids of sperm phospholipids which may result, amongst other effects, in decreased membrane fluidity.
Interactions of Adenosine Tetraphosphate with Myosin and Actomyosin
Authors: Winand‐Devigne J. , Hamoir G. , Liébecq C.
Published: March 2005

Myosin‐ATPase prepared from dog heart and rabbit skeletal muscle catalyzed the hydrolysis of adenosine tetraphosphate into adenosine diphosphate and orthophosphate.

Maximum activities were measured in the presence of Ca++ ions and represented 15 to 50% (according to pH and to origin) of the maximum activites measured in the presence of adenosine triphosphate (ATP). Low activities were measured in the presence of Co++ > Ni++ > Mg++ ions.

Actomyosin‐ATPase prepared from rabbit and from carp muscles hardly catalyzed the hydrolysis of adenosine tetraphosphate (2.5% of the rate of ATP hydrolysis) in the presence of Mg++ ions at low ionic strength.

Ultracentrifugation analysis showed that carp muscle actomyosin is split into actin and myosin by low concentrations of adenosine tetraphosphate whereas the contaminating ATP or the ATP formed from adenosine tetraphosphate during the centrifugation does not markedly influence the centrifugal pattern.
Enzymatic Synthesis of Deoxyribonucleotides
Authors: Durham L. J. , Larsson A. , Reichard P.
Published: March 2005

Deoxycytidine diphosphate was synthesized in [2H2] water from cytidine diphosphate with the ribonucleoside diphosphate reductase system from Escherichia coli B. After dephosphorylation and crystallization, deoxycytidine was analyzed by nuclear magnetic resonance at 60 and 100 megaHertz. The spectra indicated that one atom of deuterium had been introduced stereospecifically into position 2′. From earlier calculations of Lemieux [10] and our own data it is tentatively concluded that the enzyme reaction occurred without change of the stereospecificity at carbon 2′.
The Mechanism of Enzyme Secretion by the Cell
Authors: Babad H. , Ben‐Zvi R. , Bdolah A. , Schramm M.
Published: March 2005

Preparation of rat parotid slices in cold medium caused extensive leakage of amylase during subsequent incubation. Enzyme secretion, by slices not prepared in the cold, was almost absolutely dependent on the addition of an inducer such as epinephrine. Both epinephrine and norepinephrine were more effective than other agents tested. Since epinephrine was apparently consumed during incubation, a sufficient excess of the hormone was required to achieve a maximal yield of enzyme secreted into the medium. Further experiments indicated that 3′5′cyclic AMP is an intermediate in the induction of enzyme secretion by epinephrine. The dibutyryl and monobutyryl derivatives of cyclic AMP caused amylase secretion at a rate which was even slightly higher than that obtained with epinephrine. An initial lag period was apparently due to the slow penetration of such compounds into the cell.

β‐hydroxybutyrate was the only substrate which maintained a linear rate of amylase secretion up to termination of the process. The reaction stopped within 40–60 minutes when about 50% of the amylase which had been in the slice was secreted into the medium. This amount corresponded roughly to that located in the intracellular zymogen granules at zero time. Inhibitors of oxidative phosphorylation prevented enzyme secretion and caused some release of enzyme from the intracellular zymogen granules into a soluble pool within the slice. Enzyme secretion apparently required the continuous supply of energy since dinitrophenol was inhibitory even when added after onset of the process. EDTA caused discharge of amylase, presumably by releasing an endogenous inducer.
Studies on the Properties of (—)‐2‐α‐Hydroxyethyl‐Thiamine Pyrophosphate (“Active Acetaldehyde”)
Authors: Ullrich J. , Mannschreck A.
Published: March 2005

An improved enzymatic preparation of (–)‐HETPP from TPP with pig heart pyruvate dehydrogenase is described, yielding an amorphous product of satisfactory elementary analysis and constant optical rotation. The optical absorption spectrum of HETPP was recorded at various pH values and briefly explained and compared with that of TPP. The proton magnetic resonance spectrum of HETPP in deuterium oxide, as compared with those of TPP, 2‐α‐hydroxyethyl‐4‐methyl‐5‐β‐hydroxyethyl‐thiazole, and 2‐hydroxymethyl‐3,4‐dimethyl‐thiazolium iodide, afforded additional and more accurate proof for the structure of HETPP. The possibility of hydrogen exchange in the α‐position of the 2‐side chain of a model compound, 2‐hydroxymethyl‐3,4‐dimethyl‐5‐β‐hydroxyethyl‐thiazolium iodide, and of HETPP itself was checked under varying conditions. No proton exchange was found in the absence of enzyme at pH values below 8.6. HETPP, 3H‐labelled in the 2‐side chain, was prepared and treated with apo‐pyruvate decarb‐oxylase and Mg++. Unconverted HETPP from the reaction mixtures was found to have the specific radioactivity of the starting material. The experimental results are explained in terms of the 2‐α‐carbanion of HETPP being the real “TPP‐activated acetaldehyde” rather than HETPP itself as was hitherto believed.
Characterization of Ribonucleic Acid with Template Activity in Rat Liver Cytoplasm
Authors: Di Girolamo A. , Di Girolamo M. , Gaetani S. , Spadoni M. A.
Published: March 2005

Template activity of RNA from rat liver and the distribution of this activity along a sucrose gradient have been studied. The experiments were performed with RNA extracted from polysomes monosomes and ribosomal subunits.

There is no correlation between template activity of RNA extracted from polysomes and early‐labelled RNA, since template activity is distributed all along a sucrose gradient while the radioactivity after a 20 min pulse with [14C]orotic acid is almost exclusively localized in the 18–4 S region.

Stimulatory activity in the heavy regions of the gradient is due either to unique large molecules of messenger RNA or to aggregation of ribosomal RNA with messenger RNA. Our experimental results, however, seem to exclude aggregation due to the presence of bivalent ions as well as aggregates held by hydrogen bonds.

Ribosomal RNA is itself responsible for part of the template activity found in different fractions of the gradient. Ribosomal RNA extracted from monosomes prepared from polysomes by treatment with RNase, and from subunits, showed a stimulatory activity which, although inferior to that due to messenger RNA, was consistent. Experiments were performed which excluded the possibility that residual messenger still attached to ribosomal RNA was responsible for this activity.

Treatment of ribosomal RNA with chemical agents such as EDTA and urea increased the template activity in those cases where a permanent increase in hyperchromicity could be demonstrated. Although neomycin also increased stimulatory activity, it is thought unlikely, on the basis of our experiments, that this is due to a separation of the strands of RNA.
Transamidinase of Hog Kidney
Authors: Grazi E. , Vigi V. , Rossi N.
Published: March 2005

The modification of one cysteine residue of transamidinase by reaction with 5,5′‐dithiobis‐2‐nitrobenzoic acid alters the catalytic properties of the enzyme.

The Michaelis constant of transamidinase for arginine is increased and the capacity to utilize glycine and hydroxylamine as amidine acceptors is lost.

Arginine, the amidine donor substrate, protects the cysteine residue and prevents the changes in catalytic activity induced by the treatment with 5,5′‐dithiobis‐2‐nitrobenzoic acid.
The Participation of GTP‐AMP‐P Transferase in Substrate Level Phosphate Transfer of Rat Liver Mitochondria1
Authors: Heldt H. W. , Schwalbach K.
Published: March 2005

From kinetic studies on the reaction sequence of substrate level phosphorylation in rat liver mitochondria, using anaerobic ketoglutarate dismutation in the presence of oligomycin and [32P]phosphate, phosphohistidine appears to be the first intermediate to be labelled, followed by GTP. [32P]ADP rather than [32P]ATP is shown to be the main product of the reaction. The phosphorylation of AMP requires ketoglutarate and is stimulated by 2,4‐dinitrophenol.

GTP‐AMP‐P transferase is localized in the mitochondria. This conclusion is based on enzymatic assays of fractionally ectracted rat liver and of isolated mitochondria and microsomes.

Mean values for the activities of GTP‐AMP‐P transferase, nucleoside diphosphate kinase and succinic thiokinase in rat liver mitochondria are given and are compared with the rate of ketoglutarate oxidation.

A possible function of GTP‐AMP‐P transferase for the phosphorylation of endogenous AMP is discussed with regard to the compartmentation of nucleotides in the mitochondria.

A new chromatographic assay for GTP‐AMP‐P transferase is reported, an assay which is not affected by nucleoside diphosphate kinase and adenylate kinase occurring in liver homogenates. An optical enzymatic assay for nucleoside diphosphate kinase is also described.
Vergleichende Untersuchungen zur Biosynthese von Nucleotid‐Zuckern in S‐ und R‐Formen vonSalmonella minnesotaundSalmonella ruiru
Authors: Risse H. J. , Lüderitz O. , Westphal O.
Published: March 2005

About 30 R mutants derived fromSalmonella minnesotaandSalmonella ruiruand the corresponding wild‐type strains were analysed comparatively for the presence of enzymes catalyzing the synthesis of UDP‐glucose, UDP‐galactose, UDP‐N‐acetylglucosamine and UDP‐N‐acetylgalactosamine.

In the biosynthesis of the corresponding O antigens these UDP‐sugars function as precursors, whose sugar residues are transferred on to the growing polysaccharide by specific transferases. In cell‐free extracts of the strains the following enzyme activities were determined: (quantitatively) hexokinase, phosphoglucomutase, UDP‐glucose synthetase and UDP‐galactose‐4‐epimerase; (qualitatively) glucosephosphate isomerase and UDP‐N‐acetylglucosamine‐4‐epimerase; (qualitatively, in 10strains) glutamine: fructose‐6‐phosphate transaminase and (in 6strains) UDP‐N‐acetylglucosamine synthetase. Most of the mutants were found to contain the enzymes in activities equal to those found in the wild‐type strains. These mutants therefore probably have a block involving a transferase. Three mutants were identified to have a defect in UDP‐glucose synthetase synthesis. 4 mutants lacked the enzyme UDP‐N‐acetylglucosamine‐4‐epimerase. Some of these mutants have an additional block which involves a transferase. In extracts ofS. ruiruthe enzyme system of Matsuhashi and Strominger which catalyzes the conversion of TDP‐glucose to TDP‐4‐amino‐4,6‐dideoxyhexose (probably with the configuration ofd‐galactose), could be identified.
A Comparative Study of Basic, Acidic and Neutral Polypeptidyl RNases, Including Polyarginyl and Polyhistidyl Derivatives
Authors: Frensdorff A. , Wilchek M. , Sela M.
Published: March 2005

The syntheses of poly‐l‐arginyl and of poly‐l‐histidyl RNase are described. Poly‐l‐arginyl RNase was obtained by guanidisation of poly‐l‐ornithyl RNase, which, in turn, was prepared from native RNase by reacting it with δ,N‐trifluoroacetyl‐α, N‐carboxy‐l‐ornithine anhydride, with subsequent removal of the trifluoroacetyl groups with piperidine. Derivatives enriched with up to 71 arginine residues were prepared and studied. Poly‐l‐histidyl RNase was prepared by the reaction of RNase with the unprotected N‐carboxy‐l‐histidine anhydride hydrochloride. Derivatives enriched with up to 22 histidine residues per RNase molecule were obtained.

The enzymic activity of both poly‐l‐ornithyl RNase and poly‐l‐arginyl RNase towards cytidine‐2′,3′‐cyclic phosphate is only moderately affected by the attachment of the basic peptides. The activity on RNA is, on the other hand, strongly decreased in poly‐l‐ornithyl RNase and completely abolished in polyarginyl RNase, thus illustrating that the activity of the modified enzymes on these two substrates is affected independently. The pH of optimal activity of the basic polyarginyl RNase on cytidine‐2′,3′‐cyclic phosphate at low ionic strength was found to be increased in comparison to that of the native enzyme, while that of the acidic polyglutamyl RNase, the synthesis of which was previously described, was lowered. Polyhistidyl RNase was less active on RNA than the native enzyme, while its activity toward cytidine 2′,3′‐cyclic phosphate exceeded that of unmodified RNase. All the derivatives described recovered their full initial enzymic activity after complete reduction of the disulfide bridges followed by reoxidation.
Protection of Polynucleotide Phosphorylase by Substrates against Urea Inactivation
Authors: Harvey R. A. , Godefroy T. , Lucas‐Lenard J. , Grunbebg‐Manago M.
Published: March 2005

Polynucleotide phosphorylase from Escherichia coli is irreversibly inactivated by preincubation with urea at concentrations of 3.0 M or greater. The addition of ribonucleotide polymers, oligonucleotides or nucleoside diphosphates to the preincubation medium markedly decreases the rate of this inactivation. Both oligonucleotides terminated with an unesterified 3′‐hydroxyl group or esterified with a 3′‐phosphate are equally effective.

The presence of 2.0 M and 4.0 M urea in the normal reaction medium results in a complete. inhibition of the polymerization of the nucleoside diphosphates UDP and ADP, respectively. Full enzymic activity can be regained either by diluting the urea or by addition of oligonucleotides terminating with an uneserified 3′‐hydroxyl group. Long polynucleotides or oligonucleotides with a terminal 3′‐phosphate group are ineffective in restoring enzymic activity, in contrast to their ability to protect on the enzyme against irreversible denaturation.

The phosphorolysis reaction catalyzed by polynucleotide phosphorylase is appreciably inhibited only at concentrations of urea in excess of 4.0 M.

The present results suggest that at concentrations of 4.0 M or less, urea inhibits selectively and reversibly the chain initiation reaction either by drastically decreasing the binding constant of the oligonucleotide to the enzyme, or by slowing down the first steps of the polymerization.

La polynucléotide phosphorylase extraite de Escherichia coli est inactivée de façon irréversible à la suite d'une pré‐incubation avec de l'urée à des concentrations de 3 M ou plus. Cette inactivation est notablement diminuée par l'addition de polyribonucléotides, d'oligonucléotides ou de nucléosides diphosphates au milieu de préincubation. Les oligonucléotides sont actifs, qu'ils soient terminés par un groupe 3′‐hydroxyle libre, ou qu'ils soient estérifiés en 3′ phosphate.

En présence d'urée (2 M et 4 M, respectivement pour l'UDP et l'ADP) la polymérisation des nucléosides diphosphates est complétement inhibée. L'activité enzymatiquement peut être totalement rétablie, soit par dilution de l'urée, soit par addition d'oligonucléotides terminés par un groupement 3′ hydroxyle non estérifié. Les longs polynucléotides de même que les oligonucléotides terminés par un groupement 3′ phosphate, ne peuvent restaurer l'activité enzymatique, bien qu'ils puissent protéger l'enzyme contre une dénaturation irréversible.

La réaction de phosphorolyse catalysée par la polynucléotide phosphorylase n'est inhibée de façon appréciable par la présence d'urée qu'à des concentrations au dessus de 4 M.

Ces résultats suggèrent qu'à des concentrations de 4 M ou moins, l'urée inhibe la réaction d'initiation de la chaîne polynucléotidique de façon sélective et réversible; cette inhibition se produit soit par une forte diminution de la constante d'association entre l'oligonucleotide et l'enzyme, soit par un ralentissement des premières étapes de la polymérisation.
The Role of the Allosteric Sites in the X‐Ray Inactivation of Phosphorylase b
Authors: Damjanovich S. , Sanner T. , Pihl A.
Published: March 2005

Crystalline rabbit muscle phosphorylase b was irradiated in dilute aqueous solution with X‐rays. The enzyme was inactivated with a G‐value of 0.09.

Measurements of the Km values of the substrate, glucose‐1‐phosphate, and the allosteric activator, adenosine‐5′‐phosphate, demonstrated that these increased linearly with increasing radiation dose. The effect on the Km for the activator was 4 times greater than that on the Km for the substrate. The data indicate that the allosteric function is more sensitive to inactivation than the catalytic function.

The enzyme SH‐groups were destroyed by X‐rays with a G‐value of 1.8. Comparison with data on the inactivation of the enzyme by sulfhydryl blocking agents demonstrated that the X‐ray destruction of sulfhydryl groups was sufficiently large to account for the X‐ray inactivation of the enzyme.

Blocking of two SH‐groups with pCMB reduced the radiosensitivity of the enzyme by a factor of 2. Measurement of the Km values showed that the pCMB blocking protected preferentially the allosteric sites.

The data indicate that the inactivation of phosphorylase b, both by sulfhydryl agents and by X‐rays, involves largely an effect on the allosteric sites with loss of ability to bind the essential activator and consequent loss of ability to bind substrate.
Effect of Irradiation in vitro on Mitochondrial Metabolism
Authors: Clark J. B.
Published: March 2005

The ability of rat liver mitochondria to oxidise β‐hydroxybutyrate, succinate, α‐oxoglutarate, pyruvate, glutamate and isocitrate has been studied after irradiating the mitochondria in vitro with radiation doses within the range 0–100 krads.

The P/O (P/2e) ratio and the respiratory control, as well as the various mitochondrial respiratory states, have been examined by use of the oxygen electrode.

The P/O ratios of mitochondria oxidizing β‐hydroxybutyrate and succinate fell by 10% after a 100 krads dose of irradiation; after the same dose the P/O ratio with glutamate or pyruvate fell by 20% with α‐oxoglutarate 25% and with isocitrate 30%.

In all cases except isocitrate, the respiratory control fell more dramatically than the P/O ratio after irradiation. After 100 krads dose of irradiation the respiratory control of mitochondria oxidizing succinate fell by 20%; isocitrate by 30%; pyruvate or glutamate by 34%; β‐hydroxybutyrate by 37% and α‐oxoglutarate by 42%.

The results are discussed with respect to the normal control of mitochondrial citric acid cycle oxidations, the role that the structural integrity of the mitochondrion plays therein and the effects of irradiation on cellular systems in general.
Sur quelques constituants lipidiques de Corynebacterium ovis
Authors: Lacave C. , Asselineau J. , Toubiana R.
Published: March 2005

The lipids of Corynebacterium ovis (strain Bl/50) were successively extracted by petroleumether, ethanol‐ether (1:1, v/v) and chloroform.

The bulk of the petroleum‐ether extract consists mainly of sodium corynomycolate together with sodium salts of C14, C16 and C18 fatty acids. Some triglycerides and free fatty acids were also detected.

Isolated from the ethanol‐ether extract were: hydrocarbons, palmitone, free corynomycolic acid, a small amount of free corynomycolenic acid and a peptidolipid fraction. The phospholipid fraction contains a mixture of closely related compounds, having about 3.5% P. By hydrolysis, they are split into lipid components (50–70% of the initial products; mixtures of C16 and C18 fatty acids and corynomycolic acid), and water soluble components (glycerol, glycerophosphoric acid, inositol, arabinose, and small amounts of amino acids).

Complex substances, soluble in ether, having a high content of phosphorus (3.2 to 4.5%) were isolated from the chloroform extract. All of them contain glycerol, along with ethanolamine and sugars (glucose, galactose, arabinose, and a fast moving unidentified sugar) in one case, and with amino acids (chemically bound) in two other cases. Moreover, one third of the chloroform extract is made of a fraction (10.8% N and 1.3% P) insoluble in ether, which gives, by hydrolysis, 19% of lipid components and a polypeptide containing all the usual amino acids; the structure of this last fraction is discussed.
Effect of Biliary Drainage on Individual Reactions in the Conversion of Cholesterol to Taurocholic Acid
Authors: Danielsson H. , Einarsson K. , Johansson G.
Published: March 2005

The effect of biliary drainage on incorporation of acetate into cholesterol and on four different enzyme systems in the metabolic pathway from cholesterol to taurocholic acid has been studied in homogenates of rat liver. In homogenates of liver taken from bile fistula rats 48 hours after operation the extent of incorporation of acetate into cholesterol was about eighteen times greater and the extent of 7α‐hydroxylation of cholesterol about eight times greater than in homogenates of liver from control rats. The other reactions studied, the conversion of cholest‐5‐ene‐3β,7α‐diol to 7α‐hydroxycholest‐4‐en‐3‐one, the 12α‐hydroxylation of 7α‐hydroxycholest‐4‐en‐3‐one, and the 7α‐hydroxylation of taurodeoxycholic acid, were influenced much less by biliary drainage. It is suggested that the hydroxylation of cholesterol to cholest‐5‐ene‐3β, 7α‐diol might be a rate‐determining step in the conversion of cholesterol to bile acids.
Biosynthesis of Mustard Oil Glucosides:
Authors: Underhill E. W.
Published: March 2005

Apart from certain amino acids none of the nitrogenous intermediates involved in the biosynthesis of mustard oil glucosides have, untl now, been determined. Results consistent with the hypothesis — amino acids → aldehyde oximes → mustard oil glucosides — are presented for glucotropaeolin and gluconasturtin.

Administration of dl‐[2‐14C]phenylalanine and [1‐14C]phenylacetaldehyde oxime to Tropaeolum majus L. shoots resulted in a greater incorporation of the tracer from the latter into the aglycone moiety of glucotropaeolin; incorporation of 14C from phenylacetaldehyde oxime into the aglycone was without randomization. Radioactive phenylacetaldehyde oxime was isolated from T. majus shoots which were fed dl‐[2‐14C]phenylalanine.

The extent of conversion of 14C into the aglycone of gluconasturtin was similar when 3‐phenyl[1‐14C]propionaldehyde oxime and dl‐2‐amino‐4‐phenyl[2‐14C]butyric acid were fed to Nasturtium officinale R. Br. There was no randomization of labelled carbon in gluconasturtin aglycone derived from 3‐phenylpropionaldehyde oxime.
Zur Bildung von Chinolinalkaloiden in Pflanzen
Authors: Luckner M.
Published: March 2005

Within the last few years, the quinoline alkaloids viridicatine (I), viridicatol (II) and 3‐O‐me thyl viridicatine (III) have been isolated from the mycelium and culture medium of Penicillium cyclopium Westling, Penicillium puberulum Bainier and Penicillium viridicatum Westling. Two further alkaloids found in the culture medium of P. cyclopium und P. viridicatum, cyclopenine (IV) and cyclopenol (V) are benzodiazepine derivatives. We have shown, using labelled precursors with P. viridicatum strain V41 and P. cyclopium strain SM72 that cyclopenine, cyclopenol, viridicatine and viridicatol are synthesised from anthranilic acid and phenylalanine. These results, together with the easy conversion of cyclopenine and cyclopenol into viridicatine and viridicatol respectively by means of acid or alkali, suggested that an in vivo relationship could exist between these two groups of alkaloids.

In this paper we show that cyclopenine and cyclopenol are intermediates in the formation of viridicatine and viridicatol and that the transformation of the former to the latter is effected by an enzyme which we have named cyclopenase. This transformation occurs with fresh homogenised mycelium, with dried lyophilised mycelium and with mycelium free extract, that with the dead mycelium being much faster than with the other preparations. Using the mycelium free extract it was shown that the “agent of activity” depends upon pH, is not dialysable and can be destroyed by heating at 60° for 3 min, thus indicating the enzymatic nature of the transformation. Additional products of the transformation are carbon dioxide and methylamine.

Cyclopenase activity is shown to be strongest in the surface cultured mycelium of P. viridicatum, strain V41. In the surface cultured P. cyclopium, strain SM72 mycelium the activity was much less and in the submerged culture of both strains practically no activity was detected. This agrees with the observation that, under normal conditions, only P. viridicatum strain V41 produces an appreciable amount of viridicatine and viridicatol.

These experiments, together with previous work, indicate that anthranilic acid and a phenylpropane (e.g. phenylalanine) combine to give the benzodiazepines, cyclopenine and cyclopenol and these are transformed by the enzyme cyclopenase to the quinoline derivatives viridicatine and viridicatol. The detailed mechanism of this transformation is being investigated.
Two Species of DNA Polymerase Isolated from Escherichia coli
Authors: Lezius A. G. , Hennig S. B. , Menzel C. , Metz E.
Published: March 2005

Two species of DNA polymerase were isolated from E. coli. By comparison with internal standards, l‐malate dehydrogenase and creatine kinase, in sucrose gradient centrifugation, the sedimentation coefficients were determined for DNA polymerase A, s20,w= 3.8 S, and DNA polymerase B, s20,w= 4.9 S. The enzymes dissociate upon Sephadex gel filtration and basic subunits of each species having estimated molecular weights of 30,000 and 54,000, respectively, are observed together with more associated forms with molecular weights up to 170,000 and 300,000. From immunological studies, a similar protein seems to be present in both species. The two enzymes are equal in template specificity but differ in their ability to initiate de novo synthesis of dAT copolymer.
Immunochemistry of K Antigens of Escherichia coli
Authors: Hungerer D. , Jann K. , Jann B. , ØRskov F. , ØRskov I.
Published: March 2005

An acidic polysaccharide which consists of glucuronic acid, galactose and mannose in a molar ratio of 1:1:1, and which contains 2.5%O‐acetyl groups, was isolated from Escherichia coli O 9:K 30:H 12 cells.

Half the amount of the acidic polysaccharide present on the cell surface was extractable with saline at 60°. The residual polysaccharide was solubilized with 45% phenol at 65°. Purification of the two fractions was obtained by cetavlon precipitation.

Saline‐extractable and non‐extractable polysaccharide fractions were identical with respect to chemical composition, serological specificity, pK value, neutral equivalent and intrinsic viscosity.

In the ultracentrifuge, the non‐extractable polysaccharide showed one peak, wheareas the saline‐extractable fraction was inhomogenous. After treatment with diluted alkali a homogenous form of smaller particle size was obtained from both polysaccharide fractions. Alkali treatment did not alter the sugar composition of either fraction. The molecular weight of the alkali‐treated polysaccharide is about 150,000.

The acidic polysaccharide was oxidized by sodium periodate with concomitant destruction of the glucuronic acid. Galactose and mannose in the polysaccharide chain were resistant to periodate oxidation.

Acid hydrolysis gave rise to 3‐O‐β‐d‐glucuronosyl‐d‐galactose, which could be isolated in about 25% yield. No further oligosaccharides were detected in hydrolysates of the acidic polysaccharide.

Acid hydrolysis of the polysaccharide in which the carboxyl groups had been reduced gave rise to glucosyl‐galactose and a second disaccharide which consisted of mannose and glucose, the latter being obtained at very low yield.

It is concluded that the acidic polysaccharide of E. coli O 9:K 30: H 12 consists of linear subunits of a molecular weight of about 150,000. These subunits are joined through ester bonds between carboxyl groups of glucuronic acid residues and hydroxyl groups of sugar moieties. It is suggested that the trisaccharide mannosyl‐1,2‐glucuronosyl(β)1,3‐galactose is the repeating unit of the polysaccharide chain.

The acidic polysaccharide has a high affinity for the surface of red blood cells. In passive haemagglutination tests the polysaccharide‐sensitized red cells react strongly with E. coli O 9: K 30: H 12 anti OK and anti K serum but not with anti O serum.

After absorption of anti OK serum with the purified acidic polysaccharide the antiserum no longer agglutinates the encapsulated strain. The acidic polysaccharide is precipitated by K 30 antiserum. This precipitation is inhibited by glucuronic acid, β‐phenyl glucuronide and 3‐O‐β‐d‐glucuronosyl‐d‐galactose. After removal of the O‐acetyl groups the acidic polysaccharide shows reduced reactivity with K 30 antiserum. From these results we conclude that the acidic polysaccharide isolated from E. coli O 9: K 30:H 12 is the K antigen of this strain. The serologically determinant region of the K 30 antigen includes glucuronic acid and O‐acetyl groups.
pH‐abhängige magnetostatische und spektrale Eigenschaften des oxydierten Ferredoxins aus Clostridium pasterianum
Authors: Druskeit W. , Gersonde K. , Netter H.
Published: March 2005

Oxidized ferredoxin from Clostridium pasteurianum has a well defined pH‐stability range. Irreversible change of spectral and magnetic properties occurs at pH < 3.7 and > 11.5.

Spectral and magnetic properties undergo the same pH‐dependent changes. The curve of dissociation follows the behaviour of a dibasic acid and suggests the participation of at least two kinds of chelating protein‐groups in Fe‐binding, with apparent pK‐values at 4.0 and 10.5.

Dissociation of the first proton in the acid range results in a decrease of the mean magnetic susceptibility per Fe‐atom reaching a minimum of = 1000 × 10−6 cgs units at pH 7.25. Dissociation of the second proton in the alkaline range results in an increase of the susceptibility and loss of typical absorption bands at 390, 300 and 280 nm.

The magnetic data are discussed with regard to the assumption of two oxidation states of iron in oxidized clostridial ferredoxin.
Allosteric Properties of the Mg++‐Dependent Inorganic Pyrophosphatase in Mouse Liver Cytoplasm
Authors: Horn A. , Börnig H. , Thiele G.
Published: March 2005

The Mg++‐dependent inorganic pyrophosphatase of the mouse liver is localized primarily in the cytoplasm. Substrate is the complex ion MgPPi2−; free PPi2−and MgADP are strong inhibitors, while Mg3+‐ions behave as an activator for the enzyme.

The [Mg2+]/[substrate] ratio for optimum activity decreases with increasing substrate concentration. At substrate saturation and at pH‐optimum of 8.0, the optimum ratio is 10:1. Under these conditionsVmax= 3.7 μmole × min−1× mg protein−1, andKm= 1.6 × 10−5M.

The enzyme shows allosteric properties of a K‐system with homotropic and heterotropic effects. Homotropic cooperative interactions with Hill coefficients of 2 have been shown for the substrate, the inhibitor MgADP, and the activator Mg2+. Under the influence of the substrate the cooperativity of the activator decreases, while that of the inhibitor increases, the cooperativity of the substrate itself decreases by means of the activator.

If the enzyme is preincubated for 5 min at 40°, the allosteric cooperativity of the substrate is lost by desensitization. This effect is accompanied by a partial loss of activity. Pi4−> MgPP2−> Mg2+> MgADP protect the pyrophosphatase against heat inactivation.

The possibility that the pyrophosphatase reaction follows the kinetics of a substrate‐activated enzyme, which is inhibited by free pyrophosphate, could be excluded.
Bile Acids in Portal Blood of Rats Fed Different Diets and Cholestyramine
Authors: Cronholm T. , Sjövall J.
Published: March 2005

Dihydroxy and trihydroxy bile acids in the portal blood and intestinal contents of rats were analyzed by a gas chromatographic method. Cholic, hyodoxycholic, β‐muricholic, chenodeoxycholic and deoxycholic acids made up about 65, 13, 12, 5 and 5% respectively of the bile acids in portal serum. When a commercial pellet food was given about 65% of these acids were conjugated as compared with 90% when a low‐bulk semisynthetic diet was fed. The ratios between the different bile acids were similar in small intestinal contents and portal serum. The proportion of free bile acids and of hyodeoxycholic and deoxycholic acids was higher in portal blood draining the distal part of the intestine.

The total bile acid concentration was about 60 μM with large variations partly due to sampling conditions. Cholestyramine, 1% in the diet, did not change the concentration or composition of the bile acids determined.

The data obtained do not support the theory that the production of bile acids from cholesterol is regulated through a direct feedback inhibition by the bile acids returned to the liver via the portal blood.
Reaktivierung von Ammonium‐inaktivierter Glutaminsynthetase in Escherichia coli
Authors: Heilmeyer L. , Mecke D. , Holzer H.
Published: March 2005

It is known from previous work that the regulation of Glutaminesynthetase in Escherichia coli is effected by two mechanisms. First, the synthesis of GS is repressed by NH4+; and secondly, the activity of GS is regulated by inactivation and reactivation of the enzyme molecule.

In the present paper we demonstrate and characterize the reactivation of inactivated GS in intact cells of E. coli. GS is inactivated after addition of NH4+ to the culture medium. Experiments with a cell free extract from E. coli have shown, that the inactivation is mediated by a specific “inactivating enzyme”, ATP, Mg2+, and Glutamine which is probably formed from the added NH4+. The reactivation is observed, when the inactivated cells are centrifuged from the NH4+ containing medium and then resuspended in an NH4+ free medium. In about 5–7 minutes the activity increases 5–30‐fold.

Inhibitors of protein synthesis such as chloramphenicol and p‐fluoro‐phenylalanine do not affect the reactivation proces. Only a slight retardation of the reactivation is observed.

A carbon source is required for reactivation. When inactivated cells are incubated in a medium containing only salts and buffer no reactivation is observed. Probably the carbon source is metabolized to form intermediates and energy, which are needed for glutamine catabolizing reactions or for prevention of glutamine synthesis. Reactivation does not take place in the presence of NH4+i.e. under inactivating conditions. However if inactivation is inhibited by fluoride, reactivation can be observed in the presence of NH4+. When inactivated cells are incubated with fluoride only, without a carbon source in the reactivation medium, a reactivation is found.

Inactivation as well as reactivation are inhibited by thiol‐group reagents. From these results we conclude that: (a) Reactivation is independent of protein synthesis; (b) Reactivation does not require energy; (c) Probably thiol‐groups are involved in the reactivation process.
The Chemical Composition of the Cytoplasmic Membrane of Bacillus subtilis
Authors: Bishop D. G. , Rutberg L. , Samuelsson B.
Published: March 2005

The cytoplasmic membrane of Bacillus subtilis 168, prepared from cells in the stationary phase, has been found to contain protein (62%), RNA (22%) and lipid (16%).

Analyses of the membrane lipid revealed the presence of phospholipids (75%), neutral lipid (10%) and a compound identified as a diglucosyl diglyceride. The major phospholipids were diphosphatidyl glycerol and phosphatidyl ethanolamine, with small amounts of phosphatidyl glycerol and lipoamino acids.

Branched chain fatty acids comprised over 75% of the total fatty acids of both whole cells and membranes. Iso and anteiso acids with 15 and 17 carbon atoms were the major components, together with small amounts of iso acids containing 14 and 16 carbon atoms and n‐acids. No unsaturated acids were present.
Polysaccharide in vegetativen und aggregationsreifen Amöben von Dictyostelium discoideum
Authors: Malchow D. , Lüderitz O. , Westphal O. , Gerisch G. , Riedeal V.
Published: March 2005

Amoebae of the cellular slime mold, Dictyostelium discoideum, were grown in submerged culture on the following bacterial strains which differ with respect to the sugar composition of their somatic antigens (lipopolysaccharides): Salmonella london S from containing Lipid A, 2‐keto‐3‐deoxyoctonate (KDO), heptose, glucose, galactose, mannose and rhamnose; the R mutant Escherichia coli B/r, containing Lipid A, KDO, heptose, and glucose; and the R mutant Salmonella minnesota R595 containing Lipid A and KDO. While the two R strains were phagocytized spontaneously by the amoebae, the S strain S. london had to be opsonized by specific antiserum to promote phagocytosis. The amoebae were harvested either at the end of the exponential growth phase or in the aggregation competent stage of their development, i.e. 8 to 9 hours after exhaustion of the food bacteria. The yields of amoebae were independent of the bacterial strain used for cultivation and ranged from 30 to 40 g per 100 g of bacteria (dry weight).

Amoebae and supernatant media (after dialysis) were extracted by the phenol‐water method and the water‐soluble extracts obtained were fractionated by centrifugation at 100,000 ×g (sediment: S fraction; supernatant: L fraction). No significant yields of lipoplysaccharide were obtained either from amoebae or from the culture media. However, substances with the serological specificity of the lipopolysaccharides of the food bacteria were detected in the L fraction of the amoebae during the growth phase and of the culture medium after food exhaustion. Gel filtration of these fractions as well as gaschromatography and quantitative determinations of their sugar constituents showed that these specific substances represent the polysaccharide moiety of the bacterial lipopolysaccharides. β‐Hydroxymyristic acid which is a main constituent of lipid A was absent from the polysaccharides and could also not be detected in amoebae or culture media.

Besides bacteria‐specific polysaccharides the amoebae contained additional polysaccharides with sugars which are not present in the food bacteria, such as l‐fucose and d‐mannose. These amoebae‐specific substances are the subject of further studies.