Creatine deficiency syndrome caused by guanidinoacetate methyltransferase deficiency: diagnostic tools for a new inborn error of metabolism.

Hepatic guanidinoacetate methyltransferase deficiency induces a deficiency of creatine/phosphocreatine in muscle and brain and an accumulation of guanidinoacetic acid (GAA), the precursor of creatine. We describe a patient with this defect, a 4-year-old girl with a dystonic-dyskinetic syndrome in addition to developmental delay and therapy-resistant epilepsy. Several methods were used in the diagnosis of the disease: (1) the creatinine excretion in 24-hour urine was significantly lowered, whereas the creatinine concentration in plasma and in randomly collected urine was not strikingly different from control values; (2) the Sakaguchi staining reaction of guanidino compounds in random urine samples indicated an enhanced GAA excretion; (3) GAA excretion measured quantitatively by guanidino compound analysis using an amino acid analyzer was markedly elevated in random urine samples; (4) in vivo 1H magnetic resonance spectroscopy (MRS) revealed a strong depletion of creatine and an accumulation of GAA in brain; (5) in vivo phosphorus 31 MRS showed a strong decrease of the phosphocreatine resonance and a resonance identified as guanidinoacetate phosphate; and (6) in vitro 1H MRS showed an absence of creatine and creatinine resonances in cerebrospinal fluid and the occurrence of GAA in urine.

Clinical features and molecular genetic analysis of a boy with Prader-Willi syndrome caused by an imprinting defect.

Prader-Willi syndrome (PWS) is a neuroendocrine disorder caused by a non-functioning paternally derived gene(s) within the chromosome region 15q11-q13. Most cases result from microscopically visible deletions of paternal origin, or maternal uniparental disomy of chromosome 15. In both instances no recurrence has been reported.

Infection of primary cells by adeno-associated virus type 2 results in a modulation of cell cycle-regulating proteins.

It has been demonstrated that infection of primary human cells with adeno-associated viruses (AAV) leads to a decrease in cellular proliferation and to growth arrest. We analyzed the molecular basis of this phenomenon and observed that infection with AAV type 2 (AAV2) had an effect on several factors engaged in the control of the mammalian cell cycle. In particular, all of the pRB family members, pRB, p107, and p130, which are involved in G1 cell cycle checkpoint control, were affected.

Down-regulation of cyclin A gene expression upon genotoxic stress correlates with reduced binding of free E2F to the promoter.

Treatment of mammalian cells by DNA-damaging agents leads to various cellular responses. At sufficiently high dosage, cisplatin blocks cell proliferation and finally kills cells; this effect is the basis for its widespread use as an anticancer drug. Cisplatin-treated cells arrest in the G1 phase of the cell cycle, most likely due to a signal generated by the stabilization of p53 and the subsequent induction of p21WAF-1/Cip1.

Conformational dynamics and kinetics of peptide antagonist interactions with interleukin-1 receptor. Fluorescence studies using the NBD-labelled peptide AF12415.

Interleukin-1 plays a key role in the inflammatory response provoked by various disease states and inhibition of its action can bring therapeutic benefits. Steady-state and time-resolved studies of the intrinsic tryptophan fluorescence of the free soluble Type I form of interleukin-1 receptor (IL-1R) reveal that the rotational motions of the three major domains are strongly associated. Bound peptide antagonists are buried in hydrophobic regions, but a flexible association permits access to species from the aqueous phase.

p27KIP1 blocks cyclin E-dependent transactivation of cyclin A gene expression.

Cyclin E is necessary and rate limiting for the passage of mammalian cells through the G1 phase of the cell cycle. Control of cell cycle progression by cyclin E involves cdk2 kinase, which requires cyclin E for catalytic activity. Expression of cyclin E/cdk2 leads to an activation of cyclin A gene expression, as monitored by reporter gene constructs derived from the human cyclin A promoter.

Transient non-native interactions in early folding intermediates do not influence the folding kinetics of Escherichia coli tryptophan synthase beta 2 subunits.

Local structures formed in early intermediates are thought to play a key role in orientating the protein folding pathway. Here, we test whether non-native interactions formed by eight N-terminal residues in early folding intermediates of tryptophan synthase beta chains [Navon, A., Schulze, A.

A spectroscopic study of the structures of latent, active and reactive-center-cleaved type-1 plasminogen-activator inhibitor.

Type-1 plasminogen-activator inhibitor (PAI-1) was studied by Fourier-transform infrared spectroscopy, far-ultraviolet CD spectroscopy, and fluorescence-emission spectroscopy, with the aim to obtain structural information about its active form. The spectra of latent, active and reactive-center-cleaved forms of PAI-1 produced by HT-1080 cells were different. While the cleaved and the latent forms were similar with regard to their beta-structure content, comparison of the spectra of these forms with the spectra of active PAI-1 suggested a much higher degree of unordered structure for the active form compared with the latent and reactive-center-cleaved forms than previously assumed.

Anchorage-dependent transcription of the cyclin A gene.

NIH 3T3 cells cultured in suspension fail to express cyclin A and hence cannot enter S phase and divide. We show that loss of cell adhesion to substratum abrogates cyclin A gene expression by blocking its promoter activity through the E2F site that mediates its cell cycle regulation in adherent cells. In suspended cells, G0-specific E2F complexes remain bound to the cyclin A promoter.

Atypical vitamin B12-unresponsive methylmalonic aciduria in sibship with severe progressive encephalomyelopathy: a new genetic disease?

Unlabelled: We report on two siblings, a girl of 7 years and a boy of 2 years, who presented in infancy with hypotonia, athetoid movements, myopathy and severe developmental delay. The progressive clinical course was characterized by ophthalmoplegia, pyramidal tract signs, loss of visual contact and failure to thrive. The older sister died at the age of 7 years.

Adenovirus E1A activates cyclin A gene transcription in the absence of growth factors through interaction with p107.

Using the infection of quiescent human fibroblasts with adenovirus type 5 and various deletion mutants, we show that E1A can stimulate transcription of the cyclin A gene in the absence of exogenous growth factors. Required for this activity is conserved region 2 (CR2), while both the N-terminal part of E1A and CR1 are dispensable. This indicates that activation of cyclin A gene expression requires the binding of E1A to p107, while binding to either pRB or p300 is not involved in transcriptional activation.

Exclusion of SNRPN as a major determinant of Prader-Willi syndrome by a translocation breakpoint.

The predominant genetic defects in Prader-Willi syndrome (PWS) are 15q11-q13 deletions of paternal origin and maternal chromosome 15 uniparental disomy (UPD). In contrast, maternal deletions and paternal chromosome 15 UPD are associated with a different neurogenetic disorder, Angelman syndrome (AS). In both disorders, these mutations are associated with parent-of-origin specific methylation at several 15q11-q13 loci.

Effects of ventilator resistance and compliance on phrenic nerve activity in spontaneously breathing cats.

This study investigates the effects of respiratory mechanical loading and unloading on phrenic nerve activity and ventilation. Ten adult cats were anesthetized, intubated, and connected to a servocontrolled infant ventilator while breathing spontaneously in continuous positive airway pressure mode. The ventilator was then set to decrease the pressure at the airway opening in proportion to the inspiratory airflow or the volume of spontaneous breathing (resistive or elastic loading) or to increase the pressure at the airway opening accordingly (resistive or elastic unloading, also called proportional assist ventilation).

Protonation of histidine-132 promotes oligomerization of the channel-forming toxin aerolysin.

Aerolysin is a bacterial toxin that binds to a receptor on eukaryotic cells and oligomerizes to form stable, SDS-resistant, noncovalent oligomers that insert into the plasma membrane and produce well-defined channels. Little is known about the mechanisms controlling this process. Here we show that the protonation of a single histidine is required for oligomerization of aerolysin in solution.

Cell cycle regulation of the cyclin A gene promoter is mediated by a variant E2F site.

Cyclin A is involved in the control of S phase and mitosis in mammalian cells. Expression of the cyclin A gene in nontransformed cells is characterized by repression of its promoter during the G1 phase of the cell cycle and its induction at S-phase entry. We show that this mode of regulation is mediated by the transcription factor E2F, which binds to a specific site in the cyclin A promoter.

Sequential activation of cyclin E and cyclin A gene expression by human papillomavirus type 16 E7 through sequences necessary for transformation.

To investigate E7-dependent biochemical changes which are involved in cellular transformation, we analyzed the influence of human papillomavirus type 16 (HPV-16) E7 on the expression of cell cycle regulatory proteins. Expression of E7 in established rodent fibroblasts (NIH 3T3), which was shown to be sufficient for transformation of these cells, leads to constitutive expression of the cyclin E and cyclin A genes in the absence of external growth factors. Surprisingly, expression of the cyclin D1 gene, which encodes a major regulator of G1 progression, is unaltered in E7-transformed cells.

Vibrio spp. secrete proaerolysin as a folded dimer without the need for disulphide bond formation.

Proaerolysin is an extracellular dimeric protein that is secreted across the inner and outer membranes of Aeromonas spp. in separate steps. To investigate the role of protein folding in the second step, one or more cysteine residues were introduced and the mutant proaerolysins were expressed in Aeromonas hydrophila and Aeromonas salmonicida, as well as Vibrio cholerae.

[Comparison of dietary surveys in Germany and Great Britain regarding objectives, methodology and results].

Referring to the data of the National Food Consumption Study in Germany and the Dietary and Nutritional Survey of British Adults, this article compares the food intake of German and British adults. Such a comparison is possible because both studies have mainly the same methodology. The comparison of the food intake of German and British adults points out food groups which Germans consume in higher amounts than British people do.

Effect of the arterial oxygenation level on cardiac output, oxygen extraction, and oxygen consumption in low birth weight infants receiving mechanical ventilation.

Objective: To investigate the effects on oxygenation of targeting the higher versus the lower end of the currently recommended range for pulse oximetry (Spo2).

Design: Nonrandomized crossover trial with the use of within-subject comparisons (two-tailed paired t test).

Setting: Level III neonatal intensive care unit of a university hospital.