Life without myoglobin.

Hemoproteins are widely distributed among prokaryotes, unicellular eukaryotes, plants and animals [1]. Myoglobin, a cytoplasmic hemoprotein that is restricted to cardiomyocytes and oxidative skeletal myofibers in vertebrates, has been proposed to facilitate oxygen transport to the mitochondria [1-3]. This cytoplasmic hemoprotein was the first protein to be subjected to definitive structural analysis and has been a subject of long-standing and ongoing interest to biologists [1-3].

Management of duodenal perforation after endoscopic retrograde cholangiopancreatography and sphincterotomy.

Objective: To evaluate the authors' experience with periduodenal perforations to define a systematic management approach.

Summary Background Data: Traditionally, traumatic and atraumatic duodenal perforations have been managed surgically; however, in the last decade, management has shifted toward a more selective approach. Some authors advocate routine nonsurgical management, but the reported death rate of medical treatment failures is almost 50%.

Obstetric conditions and erythropoietin levels.

Objective: Our purpose was to evaluate and compare erythropoietin levels as related to obstetric conditions, including acute and chronic bleeding, preeclampsia, and multiple gestations.

Study Design: During April 1999 all women in the labor and delivery unit with delivery expected to occur within 24 to 72 hours of admission had erythropoietin and hematocrit values obtained. First-trimester hematocrit values, obstetric problems, medications, and history of vaginal bleeding were obtained from patient interview, examination, and the prenatal record.

Myogenic stem cell function is impaired in mice lacking the forkhead/winged helix protein MNF.

Myocyte nuclear factor (MNF) is a winged helix transcription factor that is expressed selectively in myogenic stem cells (satellite cells) of adult animals. Using a gene knockout strategy to generate a functional null allele at the Mnf locus, we observed that mice lacking MNF are viable, but severely runted. Skeletal muscles of Mnf-/- animals are atrophic, and satellite cell function is impaired.

Surgical management of biliary gallstone disease during pregnancy.

Background: Biliopancreatic gallstone disorders (BPD) manifesting during pregnancy are relatively rare. The management of these conditions remains controversial. Although perioperative problems and fetal loss have been reported, recent publications have advocated an early surgical approach.

Use of castor oil in pregnancies at term.

Context: Despite wide use of castor oil to initiate labor, the obstetric literature contains few references to this botanical laxative. Derived from the castor plant Ricinus communis, castor oil may possess properties that are useful in post-term pregnancies.

Objective: To evaluate the relationship between the use of castor oil and the onset of labor.

The winged-helix/forkhead protein myocyte nuclear factor beta (MNF-beta) forms a co-repressor complex with mammalian sin3B.

Winged-helix/forkhead proteins regulate developmental events in both invertebrate and vertebrate organisms, but biochemical functions that establish a mechanism of action have been defined for only a few members of this extensive gene family. Here we demonstrate that MNF (myocyte nuclear factor)-beta, a winged-helix protein expressed selectively and transiently in myogenic precursor cells of the heart and skeletal muscles, collaborates with proteins of the mammalian Sin3 (mSin3) family to repress transcription. Mutated forms of MNF-beta that fail to bind mSin3 are defective in transcriptional repression and in negative growth regulation, an overexpression phenotype revealed in oncogenic transformation assays.

Elevated Amniotic Fluid Interleukin-6 as a Predictor of Neonatal Periventricular Leukomalacia and Intraventricular Hemorrhage.

> Objective: To investigate the relationship between amniotic fluid interleukin-6 levels and the development of periventricular leukomalacia and intraventricular hemorrhage in the preterm neonate and to compare the value of amniotic fluid interleukin-6 with amniotic fluid culture and histologic chorioamnionitis in the prediction of periventricular leukomalacia and intraventricular hemorrhage. Methods: 119 women, between 20 and 34 weeks gestation, in preterm labor with intact membranes, underwent transabdominal amniocentesis. Amniotic fluid was cultured for aerobic and anaerobic bacteria, Ureaplasma urealyticum and Mycoplasma hominis.

Mice without myoglobin.

Myoglobin, an intracellular haemoprotein expressed in the heart and oxidative skeletal myofibres of vertebrates, binds molecular oxygen and may facilitate oxygen transport from erythrocytes to mitochondria, thereby maintaining cellular respiration during periods of high physiological demand. Here we show, however, that mice without myoglobin, generated by gene-knockout technology, are fertile and exhibit normal exercise capacity and a normal ventilatory response to low oxygen levels (hypoxia). Heart and soleus muscles from these animals are depigmented, but function normally in standard assays of muscle performance in vitro across a range of work conditions and oxygen availability.

Intra-amniotic pressure reduction in twin-twin transfusion syndrome.

Objective: Our purpose was to measure intra-amniotic pressure before and after decompression amniocentesis in twin-twin transfusion syndrome.

Study Design: Intra-amniotic pressures were measured during decompression amniocentesis on 18 occasions in 5 pregnancies complicated by twin-twin transfusion syndrome. The intra-amniotic pressure was determined with a water manometer before and after removal of amniotic fluid.

Differential expression of mitochondrial DNA replication factors in mammalian tissues.

Mitochondrial biogenesis and mitochondrial DNA (mtDNA) replication are regulated during development and in response to physiological stresses, but the regulatory events that control the abundance of mtDNA in cells of higher eukaryotes have not been defined at a molecular level. In this study, we observed that expression of the catalytic subunit of DNA polymerase gamma (POLgammaCAT) mRNA varies little among different tissues and is not increased by continuous neural activation of skeletal muscle, a potent stimulus to mitochondrial biogenesis. Increased copy number for the POLgamma locus in a human cell line bearing a partial duplication of chromosome 15 increased the abundance of POLgammaCAT mRNA without up-regulation of mtDNA.

Persistent expression of MNF identifies myogenic stem cells in postnatal muscles.

Skeletal muscles contain an undifferentiated myogenic stem cell pool (satellite cells) that can be mobilized to regenerate myofibers in response to injury. We have determined that the winged helix transcription factor MNF is expressed selectively in quiescent satellite cells, which do not express known regulators of the myogenic program. Following muscle injury, MNF is present transiently in proliferating satellite cells and in centralized nuclei of regenerating myofibers, but expression declines as these fibers mature, until only the residual stem cell pool continues to express detectable levels of MNF.

Correlation of neonatal nucleated red blood cell counts in preterm infants with histologic chorioamnionitis.

Objective: The aim of this study was to compare the neonatal nucleated red blood cell counts in preterm infants in the presence and absence of clinical and histologic chorioamnionitis while controlling for gestational age and birth weight percentile.

Study Design: Nucleated red blood cell counts were obtained from preterm infants delivered after preterm labor or preterm premature rupture of membranes. Patients were divided on the basis of clinical and histologic chorioamnionitis.

Temporospatial expression of the small HSP/alpha B-crystallin in cardiac and skeletal muscle during mouse development.

Although the small (22 Kd) heat shock protein/alpha B-crystallin functions as a major structural protein and molecular chaperone in the vertebrate lens, little is known about the protein's role in nonlenticular tissues such as the heart and skeletal muscle. Recent studies have demonstrated that alpha B-crystallin expression is uniquely regulated during myogenesis in vitro. We report here for the first time that the temporal and spatial expression of alpha B-crystallin is similarly regulated in vivo during mouse embryogenesis.

A comparison of rapid amniotic fluid markers in the prediction of microbial invasion of the uterine cavity and preterm delivery.

Objective: The purpose of this study was to evaluate amniotic fluid lactate dehydrogenase level in comparison with other rapid markers in prediction of microbial invasion of the uterine cavity and preterm delivery < or = 36 hours after amniocentesis.

Study Design: One hundred thirty-one women in preterm labor with intact membranes underwent transabdominal amniocentesis. Amniotic fluid was analyzed for leukocyte count, glucose level, lactate dehydrogenase level, and Gram stain.

Intrauterine transmission of hepatitis A virus.

Background: Hepatitis A is a common, self-limited disease transmitted by fecal-oral contamination.

Case: A 23-year-old woman, para 2-0-0-2, developed hepatitis A at 20 weeks' gestation. At 27 weeks, ultrasound revealed polyhydramnios and fetal ascites.

Acute myocardial infarction in pregnancy with subsequent medical and surgical management.

Background: Myocardial infarction is a rare event in pregnancy that requires medical stabilization with possible surgical interventions.

Case: A 37-year-old woman developed an anterior wall myocardial infarction secondary to severe coronary artery disease during the early third trimester of pregnancy. The patient was managed with multiple modalities to stabilize her condition and prolong the gestation.

Postnatal development and plasticity of specialized muscle fiber characteristics in the hindlimb.

Recent progress in defining molecular components of pathways controlling early stages of myogenesis has been substantial, but regulatory factors that govern the striking functional specialization of adult skeletal muscle fibers in vertebrate organisms have not yet been identified. A more detailed understanding of the temporal and spatial patterns by which specialized fiber characteristics arise may provide clues to the identity of the relevant regulatory factors. In this study, we used immunohistochemical, in situ hybridization, and Northern blot analyses to examine the time course and spatial characteristics of expression of myoglobin protein and mRNA during development of the distal hindlimb in the mouse.

Fractures in large-segment allografts.

Sixteen of thirty-five large-segment allografts that had been implanted after resection for neoplastic conditions, and had been followed for a minimum of thirty-six months, were found to have fractured at a mean of twenty-six months after the implantation. Thirteen of the fractures were treated operatively, and we found a lack of vascularization and soft-tissue attachments to the graft at the fracture site. For seven fractured grafts, there were radiographic and clinical signs of union with the host bone.

Epidermolysis bullosa acquisita induced by GM-CSF: a role for eosinophils in treatment-related toxicity.

A patient treated with granulocyte-macrophage colony-stimulating factor (GM-CSF) developed eosinophilia and epidermolysis bullosa acquisita. The bullae were subepidermal, and filled with an inflammatory infiltrate composed predominantly of eosinophils. Immunofluorescence studies disclosed linear deposition of IgG, IgA and C3 at the basement membrane zone and immunoelectron microscopy demonstrated antibody deposition in the lamina densa and sublamina densa region; however, the patient's serum did not contain circulating antibody to basement membrane zone antigens.

Structural and functional considerations of GABA in islets of Langerhans. Beta-cells and nerves.

gamma-Aminobutyric acid (GABA), a prominent inhibitory neurotransmitter, is present in high concentrations in beta-cells of islets of Langerhans. The GABA shunt enzymes, glutamate decarboxylase (GAD) and GABA transaminase (GABA-T), have also been localized in islet beta-cells. With the recent demonstration that the 64,000-M, antigen associated with insulin-dependent diabetes mellitus is GAD, there is increased interest in understanding the role of GABA in islet function.

The use of human fetal tissue: scientific, ethical, and policy concerns (January 1990).

The use of fetal tissue in transplants for treating illnesses such as Parkinson's disease and juvenile diabetes has raised the hopes of patients, their families, and the biomedical community. But, this practice has created considerable controversy. Concerns arise because tissue is usually obtained from electively aborted fetuses.