Hepatitis prevalence in trauma patients

The risks of viral transmission from trauma patients is a continuing concern to those involved in their care. However, the prevalence of hepatitis (HPT) in trauma patients is poorly described. The purpose of this study is to evaluate the prevalence of HPT in trauma patients admitted to an urban trauma center. Two hundred sixty-four consecutive admissions to an urban Level I trauma center underwent serologic screening for HPT. Risk factors were assessed by direct patient questioning. Serologic evidence of HPT B was found in 19.7 per cent of patients. Intravenous (IV) drug abusers represented eight per cent of the study population; this group had a 67 per cent rate of seropositivity. Hepatitis A was not found in any patient. Antigenemia was found in 1.9 per cent of patients. It is concluded that HPT B seropositivity is common in trauma patients. IV drug abusers have particularly high prevalence of HPT. This high prevalence rate of HPT B serology poses a significant risk to those involved with the care of trauma patients. The authors suggest that specific protocols to avoid the transmission of viral disease should be mandatory in urban trauma centers.     

Methionine residues as endogenous antioxidants in proteins

Cysteine and methionine are the two sulfur-containing residues normally found in proteins. Cysteine residues function in the catalytic cycle of many enzymes, and they can form disulfide bonds that contribute to protein structure. In contrast, the specific functions of methionine residues are not known. We propose that methionine residues constitute an important antioxidant defense mechanism. A variety of oxidants react readily with methionine to form methionine sulfoxide, and surface exposed methionine residues create an extremely high concentration of reactant, available as an efficient oxidant scavenger. Reduction back to methionine by methionine sulfoxide reductases would allow the antioxidant system to function catalytically. The effect of hydrogen peroxide exposure upon glutamine synthetase from Escherichia coli was studied as an in vitro model system. Eight of the 16 methionine residues could be oxidized with little effect on catalytic activity of the enzyme. The oxidizable methionine residues were found to be relatively surface exposed, whereas the intact residues were generally buried within the core of the protein. Furthermore, the susceptible residues were physically arranged in an array that guarded the entrance to the active site.     

Infantile glaucoma in Down's syndrome (trisomy 21)

We examined five patients with Down's syndrome and bilateral infantile glaucoma. In the first few months of life four patients had large cloudy corneas, breaks in Descemet's membrane, increased intraocular pressure, photophobia, and tearing. In one patient the diagnosis was delayed until 3 1/2 years of age because of concomitant nasolacrimal duct obstruction. Two patients developed cataracts and retinal detachment and have undergone multiple surgical procedures. The clinical course in these two older patients suggests that coexistence of congenital glaucoma, severe myopia, and cataracts in patients with trisomy 21 strongly predisposes for the development of retinal detachment and poor visual outcome.     

Myelolipoma of the thoracic spine.

We describe a myelolipoma of the thoracic spine in a patient with gradual and progressive myelopathy. MR imaging showed this predominately fatty lesion to be extradural in location.     

Naloxone administration following operant training of sucrose/water discrimination in the rat

 The suppression of food intake observed following naloxone administration has often been ascribed to palatability or taste. Unfortunately, many confounds become apparent when attempts are made to isolate such factors in the investigation of ingestive behaviors. In the present study, rats (two groups) were trained to discriminate either a 10% or 5% sucrose solution from water (0.1 ml). These mildly food deprived subjects (95% of free-feeding weight) were trained to press the appropriate lever in a two-lever operant chamber following sampling of sucrose or water; successful responding was reinforced by delivery of a 45 mg grain food pellet. Following random exposure to reduced sucrose concentrations tested under extinction, a sucrose concentration gradient (1.0, 0.5, 0.1, 0.05, 0.01 and 0.005% sucrose solution) was established for both training groups under IP saline administration. Data collected under IP saline were then compared to those collected following random IP naloxone administration (3.0, 1.0, 0.3 and 0.1 mg/kg). No significant differences were observed between the sucrose concentration gradients obtained under saline and those obtained under naloxone, suggesting that the anorectic effect of naloxone is not primarily determined by discrimination of sweet taste. Received: 4 September 1996 / Final version: 16 October 1996     

Differential modulation by dopamine of responses evoked by excitatory amino acids in human cortex.

The responses of human neocortical neurons to iontophoretic application of excitatory amino acids and their modulation by dopamine (DA) were studied in vitro. Brain slices were obtained from children undergoing surgery for intractable epilepsy. Application of N-methyl-D-aspartate (NMDA) to the slices induced slow depolarizations accompanied by decreased input conductances and sustained action potentials in cortical neurons. Glutamate produced rapid depolarizations and firing with few changes in input conductances. Quisqualate also induced depolarization and firing, but input conductances increased during the rising phase of the membrane depolarization. Iontophoretic application of DA alone produced no change in membrane potential or input conductance. However, when DA was applied in conjunction with the excitatory amino acids, it produced contrasting effects. With either bath application of DA or when iontophoresis of DA preceded application of NMDA, the amplitude of the membrane depolarizations and the number of action potentials were increased, whereas the latency of these responses decreased. In contrast, DA decreased the amplitude of the depolarizations and the number of action potentials evoked by glutamate or quisqualate. The fact that DA affects responses to NMDA and glutamate or quisqualate in opposite directions is of considerable importance to the understanding of cellular mechanisms of neuromodulation and the role of DA in cognitive processing and in epilepsy.     

Origin and characteristics of glycogen cells in the developing murine placenta.

The junctional zone (Jz) of the mouse placenta consists of two main trophoblast populations, spongiotrophoblasts and glycogen cells (GCs), but the development and function of both cell types are unknown. We conducted a quantitative analysis of GC size, number, and invasion of cells into the decidua across gestation. Furthermore, we identified markers of GC function to investigate their possible roles in the placenta. While the spongiotrophoblast cell volume doubles, and cell number increases steadily from E12.5 to E16.5, there is a remarkable 80-fold increase in GC numbers. This finding is followed by a notable decrease by E18.5. Surprisingly, the accumulation of GCs in the decidua did not fully account for the decrease in GC number in the Jz, suggesting loss of GCs from the placenta. Glucagons were detected on GCs, suggesting a steady glucose release throughout gestation. Connexin31 staining was shown to be specific for GCs. GC migration and invasion may be facilitated by temporally regulated expression of matrix metalloproteinase 9 and the imprinted gene product, Decorin. Expression of the clearance receptor for type II insulin-like growth factor (IGF-II), IGF2R, in a short developmental window before E16.5 may be associated with regulating the growth effects of IGF-II from glycogen cells and/or labyrinthine trophoblast on the expansion of the Jz. Thus stereology and immunohistochemistry have provided useful insights into Jz development and function of the glycogen cells.