Mauriac Syndrome in a 3-Year-Old Boy

ObjectiveTo report a case of Mauriac syndrome in a young child with poorly controlled type 1 diabetes mellitus.MethodsWe describe the typical features of Mauriac syndrome and review the clinical, laboratory, and ultrasound findings and follow-up results in our current patient.ResultsHepatomegaly, growth impairment, and cushingoid features characterize Mauriac syndrome. Most frequently, it is seen in adolescents and young adults with a history of poor glycemic control. In our current patient, a 3-year-old boy with type 1 diabetes mellitus of 2 years’ duration, Mauriac syndrome developed in the context of a disrupted social environment. His liver enzyme derangement, hepatomegaly, and growth improved once euglycemia was achieved.ConclusionAlthough Mauriac syndrome is currently uncommon, close monitoring of children with type 1 diabetes is important to maintain optimal glycemic control and prevent such an occurrence. (Endocr Pract. 2007;13: 63-66)     

Autophagic cell death exists

The term autophagic cell death (ACD) initially referred to cell death with greatly enhanced autophagy, but is increasingly used to imply a death-mediating role of autophagy, as shown by a protective effect of autophagy inhibition. In addition, many authors require that autophagic cell death must not involve apoptosis or necrosis. Adopting these new and restrictive criteria, and emphasizing their own failure to protect human osteosarcoma cells by autophagy inhibition, the authors of a recent Editor’s Corner article in this journal argued for the extreme rarity or nonexistence of autophagic cell death. We here maintain that, even with the more stringent recent criteria, autophagic cell death exists in several situations, some of which were ignored by the Editor’s Corner authors. We reject their additional criterion that the autophagy in ACD must be the agent of ultimate cell dismantlement. And we argue that rapidly dividing mammalian cells such as cancer cells are not the most likely situation for finding pure ACD.     

Autophagic cell death exists

The term autophagic cell death (ACD) initially referred to cell death with greatly enhanced autophagy, but is increasingly used to imply a death-mediating role of autophagy, as shown by a protective effect of autophagy inhibition. In addition, many authors require that autophagic cell death must not involve apoptosis or necrosis. Adopting these new and restrictive criteria, and emphasizing their own failure to protect human osteosarcoma cells by autophagy inhibition, the authors of a recent Editor's Corner article in this journal argued for the extreme rarity or nonexistence of autophagic cell death. We here maintain that, even with the more stringent recent criteria, autophagic cell death exists in several situations, some of which were ignored by the Editor's Corner authors. We reject their additional criterion that the autophagy in ACD must be the agent of ultimate cell dismantlement. And we argue that rapidly dividing mammalian cells such as cancer cells are not the most likely situation for finding pure ACD.     

The polymerase slips and PIPO exists

Plant viruses that contain plus‐sensed single‐stranded RNA genomes are highly abundant in nature. As the equivalents of large mRNAs, these viral genomes utilize a wide variety of gene expression strategies for the production of their encoded proteins. The potyviruses, which are among the most agriculturally important members in this category, contain a single large open reading frame (ORF) coding for a polyprotein that is processed into functional units. For many years, the products derived from the full‐length polyprotein were thought to be the only functional viral proteins. However, this notion was dispelled when an additional essential viral ORF, PIPO, was discovered encoded in an alternative reading frame. Since then, the PIPO protein—P3N‐PIPO, which mediates virus movement in plants—has been intensively studied, but its mode of expression remained elusive until now. Two articles, one in this issue of EMBO Reports, now report that slippage of the viral polymerase during viral genome replication is responsible for shifting PIPO into a translated reading frame, thereby allowing for production of P3N‐PIPO 1 2 . This mechanism of gene expression represents a novel strategy for plant viruses.     

Extracellular superoxide dismutase exists as an octamer

Human extracellular superoxide dismutase (EC-SOD) is involved in the defence against oxidative stress induced by the superoxide radical. The protein is a homotetramer stabilised by hydrophobic interactions within the N-terminal region. During the purification of EC-SOD from human aorta, we noticed that material with high affinity for heparin-Sepharose formed not only a tetramer but also an octamer. Analysis of the thermodynamic stability of the octamer suggested that the C-terminal region is involved in formation of the quaternary structure. In addition, we show that the octamer is composed of both aEC-SOD and iEC-SOD folding variants. The presence of the EC-SOD octamer with high affinity may represent a way to influence the local concentration of EC-SOD to protect tissues specifically sensitive to oxidative damage.     

Cellulolytic complex exists in cellulolytic myxobacterium Sorangium

Cellulolytic myxobacterium Sorangium can efficiently degrade cellulose materials. The cellulolytic activities are linked to cellular surfaces and organized into a large complex, which is presumed to be the protuberant structures that were found on the growing cell surfaces. The separated cellulolytic complex was determined to be 1000–2000 kDa from gel chromatogram, and contained at least cellulase and xylanase activities. The separated complex was unstable and could release smaller fractions when they stored in solution at refrigerator. There were more than ten bands on SDS-PAGE after the complex was heat-treated with SDS. The HPLC chromatogram of the complex on DIOL-300 column also supports the result.     

Evidence that gonadotrophin surge-attenuating factor exists in man

This review article summarizes the evidence provided by in-vivo and in-vitro studies suggesting that the human ovary produces a nonsteroidal factor distinct from inhibin which participates in the control of gonadotrophin secretion from the pituitary. This factor has been called gonadotrophin surge-attenuating factor (GnSAF) and is defined as attenuating the endogenous surge in luteinizing hormone (LH) in superovulated women by reducing the pituitary response to LH-releasing hormone. In-vivo bioactivity of GnSAF has been detected during the follicular phase of superovulated cycles; in-vitro studies have shown activity of this factor in human follicular fluid. From a physiological point of view, a hypothesis is proposed that GnSAF attenuates the amplitude of the positive effect of oestradiol on gonadotrophin secretion during the follicular phase of the human menstrual cycle and therefore plays an important role in controlling ovulation. If GnSAF is isolated, it may have several clinical applications including contraception.     

Coagulation factor V exists uncomplexed in bovine plasma

Bovine coagulation factor V has been examined immunochemically to ascertain whether the coagulant polypeptide (h) with M_r = 290 000–330 000 is complexed in plasma with a second immunochemically distinct polypeptide (I₂) of M_r = 400 000. Antiserum containing antibodies to h and l₂ detects the l₂ polypeptide eluting earlier than the h chain on gel filtration of plasma with either added calcium or EDTA, consistent with the behavior of a higher molecular weight noninteracting species. An immobilized monospecific antibody to l₂ removes only the l₂ polypeptide from a purified factor V preparation containing both h and l₂. Moreover, while a monospecific antibody to the h chain was able to precipitate purified radioactively labelled h chain alone or mixed with plasma, the l₂ antibody was unable to precipitate radioactively labelled h chain even after attempted recombination of the h chain with l₂ present in plasma. These studies indicate that the l₂ polypeptide is not complexed to the h chain in a purified system or in plasma and reinforce the conclusion that factor V is a single polypeptide chain uncomplexed in plasma.     

Error-threshold exists in fitness landscapes with lethal mutants

Background  

One of the important insights of quasi-species theory is an error-threshold. The error-threshold is the error rate of replication above which the sudden onset of the population delocalization from the fittest genotype occurs despite Darwinian selection; i.e., the break down of evolutionary optimization. However, a recent article by Wilke in this journal, after reviewing the previous studies on the error-threshold, concluded that the error-threshold does not exist if lethal mutants are taken into account in a fitness landscape. Since lethal mutants obviously exist in reality, this has a significant implication about biological evolution. However, the study of Wagner and Krall on which Wilke's conclusion was based considered mutation-selection dynamics in one-dimensional genotype space with the assumption that a genotype can mutate only to an adjoining genotype in the genotype space. In this article, we study whether the above conclusion holds in high-dimensional genotype space without the assumption of the adjacency of mutations, where the consequences of mutation-selection dynamics can be qualitatively different.