The role of chronic infection in children with otitis media with effusion: Evidence for intracellular persistence of bacteria

OBJECTIVE: Demonstrate mucosal bacterial infection in children with otitis media with effusion (OME). STUDY DESIGN AND SETTING: Middle ear mucosal biopsies from 11 children with OME were examined for bacteria utilizing transmission electron microscopy. This was correlated with standard culture and polymerase chain reaction (PCR) of middle ear effusions. RESULTS: Gram-positive coccal bacteria were demonstrated in middle ear mucosal epithelial cells of 4 of 11 (36%) children. Morphological appearance of bacteria and detection of pneumolysin DNA by PCR in middle ear fluid suggests a role for persistent intracellular infection with Streptococcus pneumoniae and other gram-positive cocci in some cases of OME. CONCLUSION: Intracellular bacterial infection of middle ear mucosal epithelial cells in children with OME may be an important mechanism for bacterial persistence, and contribute to inflammation and mucus production in the pathogenesis of this condition. SIGNIFICANCE: Persistent intracellular infection is a novel paradigm for OME pathogenesis in children and may influence antibiotic effectiveness in treatment of this condition.     

Renal effects of aluminium in uraemic rats and in rats with intact kidney function

The effect on renal function following administration of aluminium (i.p., five times weekly (0.05 or 0.5 mg kg-1 body weight) for 12 weeks) to partially nephrectomized (5/6 NX) or intact female rats was examined. The observed loss of concentrating ability, characterized by increased urine volume and an increased sodium excretion, as well as increased renal excretion of p-aminohippurate (demonstrable after low-dose treatment with nephrotoxins) can be interpreted as an initiation of kidney function injury. No distinct differences in response were observed between partially nephrectomized and intact animals.     

Glycosylated hemoglobin in diabetic and nondiabetic pregnancies

Fasting serum glucose and hemoglobin A1 (HbA1) levels were lower in diabetic and nondiabetic patients during the third trimester of pregnancy than in similar groups of nonpregnant subjects. HbA1 levels decreased in nine of 15 nondiabetic subjects and in nine of ten diabetic patients as pregnancy advanced. The change in HbA1 observed during pregnancy may be due to lower fasting glucose concentrations, but other physiologic changes of pregnancy such as expansion of the red cell mass and variations in fetal hemoglobin levels also may contribute to the decrease in HbA1 in the third trimester of pregnancy.     

Outcomes associated with 12 years of grant funding: the Pediatric Endocrinology Nursing Society grant program

In 1990, the Pediatric Endocrinology Nursing Society (PENS) developed a grant program to provide funding to advance pediatric endocrinology nursing practice through basic and applied research. Minimal data exist regarding the effect of grant funding on professional development and research dissemination. The purpose of this study was to determine the extent that PENS' grant funding has resulted in professional presentations, publications, and further research funding. Nineteen grants that received funding were identified. Survey questions included whether the results of the PENS-funded study were presented, published, and resulted in subsequent funding from other sources. Outcome data were available for 11 of 18 grants (61%). All funded studies were presented at PENS conference; 55% were presented at other national or international conferences. Sixteen publications resulted from seven funded studies; 64% of PENS' funded studies led to additional funding, and 18% resulted in additional research studies. In summary, the research grant program of PENS funded 19 grants, which resulted in numerous publications, presentations, and, in some cases, additional research funding from other sources. Many grant recipients acknowledged that PENS was their first source of research funding and gave them the opportunity to become experienced in their role as clinical researchers.     

Mathematical corrections for bacterial loss in pharmacodynamic in vitro dilution models.

In vitro dilution models are used to simulate in vivo drug concentration-time profiles and thus to study the effects of various antibiotic concentrations on the bacteria investigated. The major disadvantage of these models is permanent dilution of the bacterial culture, which falsifies the resulting kill curves. Known equations, which usually correct bacterial loss by simple first-order kinetics, do not take into account special test conditions, such as variable elimination rate constants, exceptionally long periods of investigation, or formation of biofilms. In the present investigation, we examined the validity of these equations with regard to the test conditions mentioned. We simulated the concentration-time curves resulting from continuous infusion of 1,000 mg of meropenem with steady-state levels of 2.5, 5.0, and 7.5 micrograms/ml in an in vitro dilution model. The resulting kill curves were compared with the kill curves obtained from incubation of bacteria in an undiluted system with meropenem at constant concentrations corresponding to the above-mentioned steady-state levels. Comparison of the matching kill curves showed that the common corrections, which do not consider the formation of biofilms in the compartments, partly overestimated the effect of bacterial dilution. We defined a factor, f, as an extension to the known equations which compensates for the effect of biofilms. Another extension was developed to allow the investigation of variable elimination rate constants. With the help of these extended mathematical corrections, we were able to fit the kill curves resulting from the in vitro dilution model exactly to the kill curves given by an undiluted system.     

Ratiometric high-resolution imaging of JC-1 fluorescence reveals the subcellular heterogeneity of astrocytic mitochondria

Using the mitochondrial potential (ΔΨ_m) marker JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide) and high-resolution imaging, we functionally analyzed mitochondria in cultured rat hippocampal astrocytes. Ratiometric detection of JC-1 fluorescence identified mitochondria with high and low ΔΨ_m. Mitochondrial density was highest in the perinuclear region, whereas ΔΨ_m tended to be higher in peripheral mitochondria. Spontaneous ΔΨ_m fluctuations, representing episodes of increased energization, appeared in individual mitochondria or synchronized in mitochondrial clusters. They continued upon withdrawal of extracellular Ca²⁺, but were antagonized by dantrolene or 2-aminoethoxydiphenylborate (2-APB). Fluo-3 imaging revealed local cytosolic Ca²⁺ transients with similar kinetics that also were depressed by dantrolene and 2-APB. Massive cellular Ca²⁺ load or metabolic impairment abolished ΔΨ_m fluctuations, occasionally evoking heterogeneous mitochondrial depolarizations. The detected diversity and ΔΨ_m heterogeneity of mitochondria confirms that even in less structurally polarized cells, such as astrocytes, specialized mitochondrial subpopulations coexist. We conclude that ΔΨ_m fluctuations are an indication of mitochondrial viability and are triggered by local Ca²⁺ release from the endoplasmic reticulum. This spatially confined organelle crosstalk contributes to the functional heterogeneity of mitochondria and may serve to adapt the metabolism of glial cells to the activity and metabolic demand of complex neuronal networks. The established ratiometric JC-1 imaging—especially combined with two-photon microscopy—enables quantitative functional analyses of individual mitochondria as well as the comparison of mitochondrial heterogeneity in different preparations and/or treatment conditions.     

The costs of emotional attention: affective processing inhibits subsequent lexico-semantic analysis

The human brain has evolved to process motivationally relevant information in an optimized manner. The perceptual benefit for emotionally arousing material, termed motivated attention, is indexed by electrocortical amplification at various levels of stimulus analysis. An outstanding issue, particularly on a neuronal level, refers to whether and how perceptual enhancement for arousing signals translates into modified processing of information presented in temporal or spatial proximity to the affective cue. The present studies aimed to examine facilitation and interference effects of task-irrelevant emotional pictures on subsequent word identification. In the context of forced-choice lexical decision tasks, pictures varying in hedonic valence and emotional arousal preceded word/ pseudoword targets. Across measures and experiments, high-arousing compared to low-arousing pictures were associated with impaired processing of word targets. Arousing pleasant and unpleasant pictures prolonged word reaction times irrespective of stimulus-onset asynchrony (80 msec, 200 msec, 440 msec) and salient semantic category differences (e.g., erotica vs. mutilation pictures). On a neuronal level, interference was reflected in reduced N1 responses (204-264 msec) to both target types. Paralleling behavioral effects, suppression of the late positivity (404-704 msec) was more pronounced for word compared to pseudoword targets. Regional source modeling indicated that early reduction effects originated from inhibited cortical activity in posterior areas of the left inferior temporal cortex associated with orthographic processing. Modeling of later reduction effects argues for interference in distributed semantic networks comprising left anterior temporal and parietal sources. Thus, affective processing interferes with subsequent lexico-semantic analysis along the ventral stream.     

Direct comparison of enzyme measurements from dried blood and leukocytes from male and female Fabry disease patients

Summary Anderson–Fabry disease is an X-linked disorder that is caused by deficiency of the lysosomal enzyme α-galactosidase A. Symptoms include chronic progressive painful small-fibre neuropathy, cornea verticillata, renal failure and heart disease. Interestingly, female heterozygous patients may also show severe symptoms. After clinical suspicion, usually the determination of α-galactosidase activity in leukocytes is requested first. Alternatively, an enzymatic assay using dried blood specimens has been described. Dried blood samples require less material and are substantially more stable (several months at room temperature) than whole-blood specimens. To validate the new method and to asses its usefulness for diagnosis of female patients, enzyme activities of α-galactosidase, β-galactosidase and β-glucuronidase from 78 known Fabry patients were compared (29 males, 47 females) between both materials. In summary, the determination of α-galactosidase activity using dried blood and leukocytes as well as the ratio of α-galactosidase to β-glucuronidase in dried blood can improve the diagnostic specificity in cases of female patients who are difficult to identify when only leukocyte enzyme activities are considered. Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Online citation: JIMD Short Report #070 (2007) Online