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We constructed yeast strains containing deletion-insertion null alleles of the RPL16A or RPL16B genes encoding the 60S ribosomal subunit protein L16 to determine the role of L16 in the synthesis and function of ribosomes. Strains lacking a functional RPL16A gene grow as rapidly as wild type, whereas those containing a null allele of RPL16B grow more slowly than wild type. RNA analysis using RPL16 probes revealed that both RPL16 genes are transcribed and that RPL16B transcripts accumulate to twice the level of RPL16A transcripts. No evidence was obtained for the occurrence of dosage compensation at the level of RPL16 mRNA accumulation in either mutant. Strains lacking both RPL16 genes are apparently inviable, demonstrating that L16 is an essential yeast ribosomal protein. Introduction of an extra copy of either RPL16 gene into rpl16b mutants restored wild-type growth rates, indicating that the two forms of the L16 protein are interchangeable. rpl16 mutants are deficient in 60S ribosomal subunits relative to 40S subunits. 43S preinitiation complexes accumulate in half-mer polyribosomes in the absence of sufficient 60S subunits. We postulate that the slow-growth phenotype of rpl16 mutants results from the perturbation of initiation of protein synthesis.

We have investigated the mechanisms whereby equimolar quantities of ribosomal proteins accumulate and assemble into ribosomes of the yeast Saccharomyces cerevisiae. Extra copies of the cry1 or RPL16 genes encoding ribosomal proteins rp59 or L16 were introduced into yeast by transformation. Excess cry1 or RPL16 mRNA accumulated in polyribosomes in these cells and was translated at wild-type rates into rp59 or L16 proteins. These excess proteins were degraded until their levels reached those of other ribosomal proteins. Identical results were obtained when the transcription of RPL16A was rapidly induced using GAL1-RPL16A promoter fusions, including a construct in which the entire RPL16A 5'-noncoding region was replaced with the GAL1 leader sequence. Our results indicate that posttranscriptional expression of the cry1 and RPL16 genes is regulated by turnover of excess proteins rather than autogenous regulation of mRNA splicing or translation. The turnover of excess rp59 or L16 is not affected directly by mutations that inactivate vacuolar hydrolases.

The binding equilibrium of deuteroporphyrin IX to human serum albumin and to bovine serum albumin was studied, by monitoring protein-induced changes in the porphyrin fluorescence and taking into consideration the self-aggregation of the porphyrin. To have control over the latter, the range of porphyrin concentrations was chosen to maker dimers (non-covalent) the dominant aggregate. Each protein was found to have one high-affinity site for deuteroporphyrin IX monomers, the magnitudes of the equilibrium binding constants (25 degrees C, neutral pH, phosphate-buffered saline) being 4.5 (+/- 1.5) X 10(7) M-1 and 1.7 (+/- 0.2) X 10(6) M-1 for human serum albumin and for bovine serum albumin respectively. Deuteroporphyrin IX dimers were found to bind directly to the protein, each protein binding one dimer, with high affinity. Two models are proposed for the protein-binding of porphyrin monomers and dimers in a porphyrin system having both species: a competitive model, where each protein molecule has only one binding site, which can be occupied by either a monomer or a dimer; a non-competitive model, where each protein molecule has two binding sites, one for monomers and one for dimers. On testing the fit of the data to the models, an argument can be made to favour the non-competitive model, the equilibrium binding constants of the dimers, for the non-competitive model (25 degrees C, neutral pH, phosphate-buffered saline), being: 8.0 (+/- 1.8) X 10(8) M-1 and 1.2 (+/- 0.6) X 10(7) M-1 for human serum albumin and bovine serum albumin respectively.

The dimerization equilibrium of deuteroporphyrin IX and of mesoporphyrin IX in aqueous solutions were studied by fluorimetric techniques over the 0.01-1 microM concentration range, where dimerization is the dominant aggregation process. Deuteroporphyrin IX was studied at several temperatures over the range 22-37 degrees C, and mesoporphyrin at 25 and 37 degrees C. The magnitudes determined for the dimerization equilibrium constants (25 degrees C, neutral pH, phosphate-buffered saline) are 2.3 × 10(6)M-1 and 5.4 × 10(6)M-1 for the deutero and meso derivatives respectively. The meso, deutero and haemato species tested show a similar temperature effect, namely dimerization decreasing with increasing temperature, indicating the involvement of a negative enthalpy change. Van't Hoff isochore of the dimerization constants determined for deuteroporphyrin IX was linear within the temperature range of 22-37 degrees C, allowing the calculation of the thermodynamic parameters. For deuteroporphyrin dimerization, those were found to be delta G0 = −36. 4kJ X mol-1; delta H0 = −46. 0kJ X mol-1 and delta S0 = −32.2J X K-1 X mol-1 (at neutral pH, 25 degrees C, phosphate-buffered saline), showing the process to be enthalpy-driven. Similar trends have been found for porphyrin species other than those studied here. Our data fit with a hypothesis giving a major role to the solvent in driving porphyrins to aggregate in aqueous solution. The magnitudes and directions of the energetic changes fit better with the expectation of the ‘ solvophobic force’ theory predicting enthalpy-driven association, than with the classic hydrophobic bonding, predicting the association to be entropy-driven.

To initiate a genetic analysis of yeast ribosomal protein gene promoters, we have constructed a gene fusion between the yeast ribosomal protein gene RP39A and the Escherichia coli lacZ gene. This gene fusion contains approximately 1,030 nucleotides of the 5' flanking region and the first 49 1/3 codons of RP39A fused in frame to a large 3' end fragment of lacZ. Whether it is introduced into yeast cells on a moderately high-copy-number plasmid, or integrated into the yeast genome at the RP39A locus, this RP39A-lacZ gene directs the synthesis of a hybrid transcript which encodes beta-galactosidase activity. Deletions in the 5' flanking region of RP39A-lacZ were constructed by linker insertion and BAL 31 mutagenesis. The expression of the mutant genes in yeast cells was assayed by measuring RP39A-lacZ mRNA and beta-galactosidase levels. By these means we have shown that the sequences between nucleotides -256 and -170 upstream of RP39A are essential for expression of this gene. Three sequence motifs, HOMOL1, RPG, and a T-rich region, which were found in that order 5'----3' upstream of most yeast ribosomal protein genes, were present within this interval. We found that substitution of the CYC1-lacZ upstream activation site with the fragment from nucleotides -298 to -172 upstream of RP39A, containing the HOMOL1-RPG-T-rich motif in that 5'----3' orientation, fully restored expression of the CYC1-lacZ gene. The essentially of HOMOL1, the RPG sequence, and the T-rich region for wild-type levels of expression of RP39A, the conserved location and order of these sequence motifs in yeast ribosomal protein genes, and the ability of a DNA fragment carrying these three sequence elements to substitute for the upstream activation site regions of CYC1 indicate that these three oligonucleotides may be essential to the transcription of yeast ribosomal protein genes.

The temperature dependence of two kinetic properties of the GT2Pisoform of microsomal UDP-glucuronosyltransferase was studied for enzyme in intact microsomes and for pure enzyme reconstituted into different types of lipid bilayers. The properties studied were the non-Michaelis-Menten kinetics of the enzyme and activity at Vmax(app). For enzyme in intact microsomes, the pattern of non-Michaelis-Menten kinetics was seen at all temperatures in the range tested (23 to 48 °C), and the slopes of the Hill plots of the data were constant across this range of temperatures. Although non-Michaelis-Menten kinetics were present for pure enzyme in bilayers of 1,2-dimyristoylphosphatidylcholine or 1,2-dipalmitoylphosphatidylcholine only in the gel phase (Hockman, Y., Kelley, M., and Zakim, D. (1983) J. Biol. Chem.258, 6509–6519), it was not possible to reconstitute this pattern of kinetics for enzyme at T> 40 °C. For example, GT2Pdisplayed Michaelis-Menten kinetics in bilayers of 1,2-distearoylphosphatidylcholine at 44 °C. For enzyme in microsomes, activities at Vmax(app)increased with increasing temperature in the range 23 to 48 °C, with a discontinuity in the slope of the Arrhenius plot at 34 °C. This thermotropic property also could not be reconstituted with pure GT2P. Instead, activities at Vmax(app)for GT2Preconstituted in 1,2-dioleoylphosphatidylcholine, 1,2-distearoylphosphatidylcholine, or 1,2-stearoyl oleoylphosphatidylcholine increased in the range 23 to 37 °C, but then decreased at T> 37 °C. The fall in activity at T> 37 °C was reversible, indicating that GT2Pundergoes a reversible change at 37 °C to a less active form of the enzyme. The differences between pure, reconstituted GT2Pand microsomal GT2Pindicate that the thermotropic properties of the microsomal enzyme are not properties of the enzyme per sebut depend on interactions between it and other components in the microsome. The data suggest, therefore, that the properties of GT2Pin microsomes results in part from an organization of components in the microsomal membrane.

In a previous paper the author, using a method of successive approximations, verified by means of the Einstein-Maxwell equations of general relativity the well-known result that outgoing electromagnetic radiation from a source conveys energy, so that the source loses gravitational mass corresponding to this energy. The purpose of this work is to show a similar result for the general case of any mixture of outgoing and incoming radiation.

The Sachs news function, which is a generalized form of the Bondi news function and which mathematically controls the entire development of the gravitational waves from any isolated system, is calculated for a cohesive system in terms of the multiple-order moments of the material energy tensorTikfor the source. A formula for the rate at which the source loses mass is then determined, and it turns out that this represents the rate of transmission of radiation energy from the source, as expected. Si calcola per un sistema coesivo la funzione di notizia di Sachs, che è una forma gencralizzata della funzione di notizia di Bondi e che controlla matematicamente l’intero sviluppo delle onde gravitazionali di ogni sistema isolato, in termini di momenti di ordine multiplo del tensoreTikdell’energia materiale per la sorgente. Si determina poi una formula per la velocità con cui la sorgente perde massa, e risulta che questa rappresenta la velocità di trasmissione di energia raggiante dalla sorgente, come ci si attendeva. Дль кОгЕжИОННОИ сИст ЕМы ЧЕРЕж МУльтИпОльНыЕ МОМЕН ты тЕНжОРА тikДль ИстО ЧНИкА ВыЧИсльЕтсь ФУ НкцИь сАксА, кОтОРАь п РЕДс ВыЧИсльЕтсь ФУНкцИь сАксА, кОтОРАь пРЕДст АВльЕт ОБОБЩЕННУУ ФО РМУ ФУНкцИИ БОНДА И кО тОРАь МАтЕМАтИЧЕскИ кОНтРОлИРУЕт пОлНОЕ РАжВИтИЕ гРА ОБОБЩЕННУУ ФОРМУ ФУН кцИИ БОНДА И кОтОРАь М АтЕМАтИЧЕскИ кОНтРО лИРУЕт пОлНОЕ РАжВИт ИЕ гРАВИтАцИОННых ВО лН От лУБОИ ИжОлИРОВА ННОИ сИстЕМы. жАтЕМ Оп РЕДЕльЕтсь ФОРМУлА Д ль ИНтЕНсИВ МАтЕМАтИЧЕскИ кОНтР ОлИРУЕт пОлНОЕ РАжВИ тИЕ гРАВИтАцИОННых В ОлН От лУБОИ ИжОлИРОВ АННОИ сИстЕМы. жАтЕМ О пРЕДЕльЕтсь ФОРМУлА Дль ИНтЕНсИВНОстИ, пР И кОтОРОИ ИстОЧНИк тЕ РьЕт МАссУ. ОтМЕЧАЕтс ь, ЧтО ЁтА ИНтЕНсИВНОс ть, кАк И ОжИДА гРАВИтАцИОННых ВОлН От лУБОИ ИжОлИРОВАНН ОИ сИстЕМы. жАтЕМ ОпРЕ ДЕльЕтсь ФОРМУлА Дль ИНтЕНсИВНОстИ, пРИ кО тОРОИ ИстОЧНИк тЕРьЕ т МАссУ. ОтМЕЧАЕтсь, Чт О ЁтА ИНтЕНсИВНОсть, к Ак И ОжИДАлОсь, пРЕДст АВльЕт ИНтЕНсИВНОст ь пЕРЕНОсА ЁНЕРгИИ Иж лУЧЕНИь От ИстОЧНИкА. жАтЕМ ОпРЕДЕльЕтсь Ф ОРМУлА Дль ИНтЕНсИВН ОстИ, пРИ кОтОРОИ ИстО ЧНИк тЕРьЕт МАссУ. ОтМ ЕЧАЕтсь, ЧтО ЁтА ИНтЕН сИВНОсть, кАк И ОжИДАл Ось, пРЕДстАВльЕт ИНт ЕНсИВНОсть пЕРЕНОсА ЁНЕРгИИ ИжлУЧЕНИь От ИстОЧНИкА. кОтОРОИ ИстОЧНИк тЕР ьЕт МАссУ. ОтМЕЧАЕтсь, ЧтО ЁтА ИНтЕНсИВНОст ь, кАк И ОжИДАлОсь, пРЕД стАВльЕт ИНтЕНсИВНО сть пЕРЕНОсА ЁНЕРгИИ ИжлУЧЕНИь От ИстОЧНИ кА. ИНтЕНсИВНОсть, кАк И О жИДАлОсь, пРЕДстАВль Ет ИНтЕНсИВНОсть пЕР ЕНОсА ЁНЕРгИИ ИжлУЧЕ НИь От ИстОЧНИкА. ИНтЕНсИВНОсть пЕРЕН ОсА ЁНЕРгИИ ИжлУЧЕНИ ь От ИстОЧНИкА. ИстОЧНИкА.

Abstract: Objective: To evaluate the pharmacokinetic parameters of morphine and lidocaine after a single intravenous dose in critically ill patients. Design: Prospective, clinical study. Setting: General intensive care unit (ICU) in a university hospital. Patients: Patients admitted to the ICU with severe systemic inflammatory response syndrome of various etiologies. Interventions: A single intravenous dose of morphine (0.025 mg/kg) and lidocaine (1.5 mg/kg) were given separately 12–36 h after admission, and arterial blood samples for serum drug levels were taken. Measurements and results: Morphine pharmacokinetics were studied in 30 patients. The clearance (Cl) was found to be 5.7 � 2.3 ml/kg per min, volume of distribution of the central compartment (Vc) 0.16 � 0.12 l/kg and volume of distribution at steady state (Vss) 1.08 � 0.69 l/kg. These values are lower then those described previously for healthy volunteers (33.5 � 9 ml/kg per min, 1.01 � 0.31 l/kg, and 5.16 � 1.4 l/kg, respectively), and similar to those described in trauma and burned patients. Lidocaine pharmacokinetics were tested in 24 subjects. The Cl was 6.9 � 3.8 ml/kg per min, Vc 0.25 � 0.1 l/kg and Vss 0.78 � 0.26 l/kg. These values are not different from parameters published previously for healthy volunteers (10 ml/kg per min, 0.53 l/min and 1.32 l/min, respectively). No correlation was found between clinical variables and pharmacokinetic parameters of both drugs (ANOVA). Conclusions: Both morphine and lidocaine have a reduced volume of distribution in critically ill patients. The normal lidocaine clearance indicates preserved hepatic blood flow and suggests that other mechanisms are involved in the reduced morphine clearance. These findings may have application for the treatment of ICU patients.

I-cell disease (ICD) is associated with skeletal dysplasia. However, changes of the intervertebral disks had not been previously reported. We describe a child with clinical and laboratory evidence of ICD who had multiple intervertebral disk calcifications. Since an excessive degeneration of the cartilage had previously been found in ICD, we propose that this process may give rise to calcification of the intervertebral disks in patients with ICD.

Ce travail a pour but d'établir si les lampes LED (Lampes à diodes électroluminescentes ou Light Emitting Diodes) sont au moins équivalentes aux lampes halogènes en terme d'efficacité de polymérisation des composites de collage orthodontiques.

L'objectif de cette étude est d'analyser l'évolution et la variation de la forme d'arcade avant et après traitement, chez des patients porteurs de fentes labio-alvéolaires palatines unilatérales.