Effects of Cognitive Inhibition Preceding Voluntary Step Responses to Visual Stimuli in Young and Older Adults

OBJECTIVES

Age-related changes in executive functions, especially inhibitory control, correlate to decreased balance control and increased fall risk. However, only a few studies focused on the performance of tasks integrating balance and inhibitory control. This study aims to determine the effects of cognitive inhibition preceding the initiation of voluntary steps in young and older adults.

METHODS

Performance of 3 stepping tasks (a Simon, Flanker, and a combined Simon-Flanker task [SFT]) were analyzed in 23 young adults and 43 older adults. Each task included congruent and incongruent trials in different step directions. Analyses focused on temporal aspects of step responses as identified by changes in Center of Pressure (CoP) and foot position. A 3-way repeated-measures ANOVA was used to evaluate "inhibition," "age," and "task" effects.

RESULTS

With large effect sizes, "inhibition" as well as "age" resulted in longer durations of an initial preparatory phase as well as the step response phase. The SFT showed the largest "task" effects. Duration of CoP movement had the largest impact on total step execution in older adults. A significant interaction effect of "age*inhibition" was found on the duration of CoP movement, but not on CoP onset.

DISCUSSION

Overall, our results demonstrate that cognitive inhibition has more impact in older adults, the longer duration of CoP movements in older adults may reflect an ineffective step preparation. Our examination of the duration of subsequent phases which comprise perceptual processing and conflict resolution, response initiation, and step execution sheds light on how cognitive inhibition affects voluntary stepping behavior in young and older adults.

Mid-infrared interference coatings with excess optical loss below 10 ppm

We present high-reflectivity substrate-transferred single-crystal GaAs/AlGaAs interference coatings at a center wavelength of 4.54 μm with record-low excess optical loss below 10 parts per million. These high-performance mirrors are realized via a novel microfabrication process that differs significantly from the production of amorphous multilayers generated via physical vapor deposition processes. This new process enables reduced scatter loss due to the low surface and interfacial roughness, while low background doping in epitaxial growth ensures strongly reduced absorption. We report on a suite of optical measurements, including cavity ring-down, transmittance spectroscopy, and direct absorption tests to reveal the optical losses for a set of prototype mirrors. In the course of these measurements, we observe a unique polarization-orientation-dependent loss mechanism which we attribute to elastic anisotropy of these strained epitaxial multilayers. A future increase in layer count and a corresponding reduction of transmittance will enable optical resonators with a finesse in excess of 100 000 in the mid-infrared spectral region, allowing for advances in high resolution spectroscopy, narrow-linewidth laser stabilization, and ultrasensitive measurements of various light-matter interactions.

Emerging echinocandin-resistant Candida albicans and glabrata in Switzerland

Echinocandins represent the first-line therapy of candidemia. Echinocandin resistance among Candida spp. is mainly due to acquired FKS mutations. In this study, we report the emergence of FKS-mutant Candida albicans/glabrata in Switzerland and provide the microbiological and clinical characteristics of 9 candidemic episodes. All patients were previously exposed to echinocandins (median 26 days; range 15–77). Five patients received initial echinocandin therapy with persistent candidemia in 4 of them. Overall mortality was 33%.

Near-infrared scanning cavity ringdown for optical loss characterization of supermirrors

A cavity ringdown system for probing the spatial variation of optical loss across high-reflectivity mirrors is described. This system is employed to examine substrate-transferred crystalline supermirrors and to quantify the effect of manufacturing process imperfections. Excellent agreement is observed between the ringdown-generated spatial measurements and differential interference contrast microscopy images. A 2-mm diameter ringdown scan in the center of a crystalline supermirror reveals highly uniform coating properties with excess loss variations below 1 ppm.

Accuracy of Sensititre YeastOne echinocandins epidemiological cut-off values for identification of FKS mutant Candida albicans and Candida glabrata: a ten year national survey of the Fungal Infection Network of Switzerland (FUNGINOS)

OBJECTIVES

Echinocandins represent the first-line treatment of candidaemia. Acquired echinocandin resistance is mainly observed among Candida albicans and Candida glabrata and is associated with FKS hotspot mutations. The commercial Sensititre YeastOne™ (SYO) kit is widely used for antifungal susceptibility testing, but interpretive clinical breakpoints are not well defined. We determined echinocandins epidemiological cut-off values (ECV) for C. albicans/glabrata tested by SYO and assessed their ability to identify FKS mutants in a national survey of candidaemia.

METHODS

Bloodstream isolates of C. albicans and C. glabrata were collected in 25 Swiss hospitals from 2004 to 2013 and tested by SYO. FKS hotspot sequencing was performed for isolates with an MIC≥ECV for any echinocandin.

RESULTS

In all, 1277 C. albicans and 347 C. glabrata were included. ECV 97.5% of caspofungin, anidulafungin and micafungin were 0.12, 0.06 and 0.03 μg/mL for C. albicans, and 0.25, 0.12 and 0.03 μg/mL for C. glabrata, respectively. FKS hotspot sequencing was performed for 70 isolates. No mutation was found in the 52 'limit wild-type' isolates (MIC=ECV for at least one echinocandin). Among the 18 'non-wild-type' isolates (MIC>ECV for at least one echinocandin), FKS mutations were recovered in the only two isolates with MIC>ECV for all three echinocandins, but not in those exhibiting a 'non-wild-type' phenotype for only one or two echinocandins.

CONCLUSION

This 10-year nationwide survey showed that the rate of echinocandin resistance among C. albicans and C. glabrata remains low in Switzerland despite increased echinocandin use. SYO-ECV could discriminate FKS mutants from wild-type isolates tested by SYO in this population.

Disk patch resonators for cavity quantum electrodynamics at the terahertz frequency

We designed disk patch resonators to meet the requirements for enhanced coupling of optical cavities to intersubband transitions in heterostructures in the terahertz frequency regime. We applied modifications to the standard patch resonator in the form of a chain of holes and slits to control the resonator eigenmodes featuring quality factors ωFWHM/ω₀ as high as 40. Due to the broken rotational symmetry of the resonators the individual eigenmodes can be accessed selectively depending on the incidence and the polarization of the THz wave. The demonstrated post-process blue-shifting of the resonance frequency up to 50% is a key tuning knob for an optimization of light-matter interaction in a quantum system.

High-Power Growth-Robust InGaAs/InAlAs Terahertz Quantum Cascade Lasers

We report on high-power terahertz quantum cascade lasers based on low effective electron mass InGaAs/InAlAs semiconductor heterostructures with excellent reproducibility. Growth-related asymmetries in the form of interface roughness and dopant migration play a crucial role in this material system. These bias polarity dependent phenomena are studied using a nominally symmetric active region resulting in a preferential electron transport in the growth direction. A structure based on a three-well optical phonon depletion scheme was optimized for this bias direction. Depending on the sheet doping density, the performance of this structure shows a trade-off between high maximum operating temperature and high output power. While the highest operating temperature of 155 K is observed for a moderate sheet doping density of 2 × 1010 cm-2, the highest peak output power of 151 mW is found for 7.3 × 1010 cm-2. Furthermore, by abutting a hyperhemispherical GaAs lens to a device with the highest doping level a record output power of 587 mW is achieved for double-metal waveguide structures.

Broadband terahertz amplification in a heterogeneous quantum cascade laser

We demonstrate a broadband terahertz amplifier based on ultrafast gain switching in a quantum cascade laser. A heterogeneous active region is processed into a coupled cavity metal-metal waveguide device and provides broadband terahertz gain that allows achieving an amplification bandwidth of more than 500 GHz. The temporal and spectral evolution of a terahertz seed pulse, which is generated in an integrated emitter section, is presented and an amplification factor of 21 dB is reached. Furthermore, the quantum cascade amplifier emission spectrum of the emerging sub-nanosecond terahertz pulse train is measured by time-domain spectroscopy and reveals discrete modes between 2.14 and 2.68 THz.

Coupled cavity terahertz quantum cascade lasers with integrated emission monitoring

We demonstrate the on-chip generation and detection of terahertz radiation in coupled cavity systems using a single semiconductor heterostructure. Multiple sections of a terahertz quantum cascade laser structure in a double-metal waveguide are optically coupled and operate either as a laser or an integrated emission monitor. A detailed analysis of the photon-assisted carrier transport in the active region below threshold reveals the detection mechanism for photons emitted by the very same structure above threshold. Configurations with a single laser cavity and two coupled laser cavities are studied. It is shown that the integrated detector can be used for spatial sensing of the light intensity within a coupled cavity.

Intracellular localization of the BCL-2 family member BOK and functional implications

The pro-apoptotic BCL-2 family member BOK is widely expressed and resembles the multi-BH domain proteins BAX and BAK based on its amino acid sequence. The genomic region encoding BOK was reported to be frequently deleted in human cancer and it has therefore been hypothesized that BOK functions as a tumor suppressor. However, little is known about the molecular functions of BOK. We show that enforced expression of BOK activates the intrinsic (mitochondrial) apoptotic pathway in BAX/BAK-proficient cells but fails to kill cells lacking both BAX and BAK or sensitize them to cytotoxic insults. Interestingly, major portions of endogenous BOK are localized to and partially inserted into the membranes of the Golgi apparatus as well as the endoplasmic reticulum (ER) and associated membranes. The C-terminal transmembrane domain of BOK thereby constitutes a 'tail-anchor' specific for targeting to the Golgi and ER. Overexpression of full-length BOK causes early fragmentation of ER and Golgi compartments. A role for BOK on the Golgi apparatus and the ER is supported by an abnormal response of Bok-deficient cells to the Golgi/ER stressor brefeldin A. Based on these results, we propose that major functions of BOK are exerted at the Golgi and ER membranes and that BOK induces apoptosis in a manner dependent on BAX and BAK.

In vitro differentiation of near-unlimited numbers of functional mouse basophils using conditional Hoxb8

BACKGROUND

Basophils constitute a rare leukocyte population known for their effector functions in inflammation and allergy, as well as more recently described immunoregulatory roles. Besides their low frequency, functional analysis of basophils is hindered by a short life span, inefficient ex vivo differentiation protocols, and lack of suitable cell models. A method to produce large quantities of basophils in vitro would facilitate basophil research and constitute a sought-after tool for diagnostic and drug testing purposes.

METHODS

A method is described to massively expand bone marrow-derived basophils in vitro. Myeloid progenitors are conditionally immortalized using Hoxb8 in the presence of interleukin-3 (IL-3) and outgrowing cell lines selected for their potential to differentiate into basophils upon shutdown of Hoxb8 expression.

RESULTS

IL-3-dependent, conditional Hoxb8-immortalized progenitor cell lines can be expanded and maintained in culture for prolonged periods. Upon shutdown of Hoxb8 expression, near-unlimited numbers of mature functional basophils can be differentiated in vitro within six days. The cells are end-differentiated and short-lived and express basophil-specific surface markers and proteases. Upon IgE- as well as C5a-mediated activation, differentiated basophils release granule enzymes and histamine and secrete Th2-type cytokines (IL-4, IL-13) and leukotriene C4. IL-3-deprivation induces apoptosis correlating with upregulation of the BH3-only proteins BCL-2-interacting mediator of cell death (BIM) and p53 upregulated modulator of apoptosis (PUMA) and downregulation of proviral integration site for Moloney murine leukemia virus 1 kinase (PIM-1).

CONCLUSION

A novel method is presented to generate quantitative amounts of mouse basophils in vitro, which moreover allows genetic manipulation of conditionally immortalized progenitors. This approach may represent a useful alternative method to isolating primary basophils.

Low dose endoluminal photodynamic therapy improves murine T cell-mediated colitis

BACKGROUND AND STUDY AIMS

Low dose photodynamic therapy (LDPDT) may modify the mucosal immune response and may thus provide a therapy for Crohn's disease. We evaluated the efficacy and safety of this technique in a murine T cell-mediated colitis model.

METHODS

The safety of LDPDT was first tested in BALB/c mice. Naïve T cells were used to induce colitis in mice with severe combined immunodeficiency, which were followed up endoscopically, and a murine endoscopic index of colitis (MEIC) was developed. The efficacy of LDPDT (10 J/cm (2); delta-aminolevulinic acid, 15 mg/kg bodyweight) was then tested on mice with moderate colitis, while a disease control group received no treatment. The MEIC, weight, length, and histology of the colon, cytokine expression indices, number of mucosal CD4 (+) T cells, percentage of apoptotic CD4 (+) T cells, body weight, and systemic side effects were evaluated.

RESULTS

LDPDT improved the MEIC ( P = 0.011) and the histological score ( P = 0.025), diminished the expression indices of the proinflammatory cytokines, interleukin-6 ( P = 0.042), interleukin-17 ( P = 0.029), and interferon-gamma ( P = 0.014), decreased the number of mucosal CD4 (+) T cells, and increased the percentage of apoptotic CD4 (+) T cells compared with the disease control group. No local or systemic side effects occurred.

CONCLUSION

LDPDT improves murine T cell-mediated colitis, decreases the proinflammatory cytokines interleukin-6, interleukin-17, and interferon-gamma, and decreases the number of CD4 (+) T cells. No adverse events were observed. Therefore, this technique is now being evaluated in patients with inflammatory bowel disease.

Deletion at 3p25.3-p23 is frequently encountered in endocrine pancreatic tumours and is associated with metastatic progression

For several reasons, chromosome 3p is thought to be involved in the pathogenesis of sporadic endocrine pancreatic tumours (EPTs): von Hippel-Lindau's disease (VHL gene at 3p25.5) is associated with EPTs; 3p is frequently involved in solid human tumours; and comparative genomic hybridization has identified frequent losses at 3p in EPTs. This study investigated 99 benign and malignant tumours, including 20 metastases, from 82 patients, by microsatellite loss of heterozygosity (LOH) analysis and fluorescence in situ hybridization (FISH) in order to evaluate the importance of chromosome 3p deletions in the molecular pathogenesis and biological behaviour of EPTs, to elaborate a common region of deletion, and to narrow down putative tumour suppressor gene loci. Allelic losses of 3p were found in 58/99 (58.6%) of tumours in 45/82 (54.9%) patients; analysis of seven microsatellite markers (3p26-p21) revealed a common region of LOH at 3p25.3-p23. The LOH frequency was significantly higher in malignant than in benign neoplasms (70.2% versus 28.0%; p=0.001). In addition, a strong correlation was found between the loss of alleles on chromosome 3p and clinically metastatic disease (LOH of 73.7% in metastasizing versus 41.5% in non-metastasizing tumours; p=0.008). EPTs from these patients showed a tendency towards losing large parts or the entire short arm of chromosome 3 with tumour progression. Furthermore, FISH analysis revealed complete loss of chromosome 3 in ten out of 37 EPTs (27%). These results indicate that a putative tumour suppressor gene at 3p25.3-p23 may play a role in the oncogenesis of sporadic EPTs and that losses of larger centromeric regions are associated with metastatic progression.

Survivors with bad outcome after hypoxic-ischaemic encephalopathy: full-term neonates compare unfavourably with children

Hypoxic-ischaemic encephalopathy (HIE) is of major importance in neonatal and paediatric intensive care with regard to mortality and long-term morbidity. Our aim was to analyse our data in full-term neonates and children with special regard to withdrawal of life support and bad outcome.

PATIENTS

All patients with HIE admitted to our unit from 1992-96 were analysed. Criteria for HIE were presence of a hypoxic insult followed by coma or altered consciousness with or without convulsions. Severity of HIE was assessed in neonates using Sarnat stages, and in children the duration of coma. In the majority of cases staging was completed with electrophysiological studies. Outcome was described using the Glasgow Outcome Scale. Bad outcome was defined as death, permanent vegetative state or severe disability, good outcome as moderate disability or good recovery.

RESULTS

In the neonatal group (n = 38) outcome was significantly associated with Sarnat stages, presence of convulsions, severely abnormal EEG, cardiovascular failure, and multiple organ dysfunction (MOD). A bad outcome was observed in 27 cases with 14 deaths and 13 survivors. Supportive treatment was withdrawn in 14 cases with 9 subsequent deaths. In the older age group (n = 45) outcome was related to persistent coma of 24-48 h, severely abnormal EEG, cardiovascular failure, liver dysfunction and MOD. A bad outcome was found in 36 cases with 33 deaths and 3 survivors. Supportive treatment was withdrawn in 15 instances, all followed by death.

CONCLUSIONS

Overall, neonates and older patients did not differ with regard to good or bad outcome. However, in the neonatal group there were significantly more survivors with bad outcome, either overall or after withdrawal of support. Possible explanations for this difference include variability of hypoxic insult, maturational and metabolic differences, and the more compliant neonatal skull, which prevents brainstem herniation.

Survivors with bad outcome after hypoxic-ischaemic encephalopathy: full-term neonates compare unfavourably with children

Hypoxic-ischaemic encephalopathy (HIE) is of major importance in neonatal and paediatric intensive care with regard to mortality and long-term morbidity. Our aim was to analyse our data in full-term neonates and children with special regard to withdrawal of life support and bad outcome.

PATIENTS

All patients with HIE admitted to our unit from 1992-96 were analysed. Criteria for HIE were presence of a hypoxic insult followed by coma or altered consciousness with or without convulsions. Severity of HIE was assessed in neonates using Sarnat stages, and in children the duration of coma. In the majority of cases staging was completed with electrophysiological studies. Outcome was described using the Glasgow Outcome Scale. Bad outcome was defined as death, permanent vegetative state or severe disability, good outcome as moderate disability or good recovery.

RESULTS

In the neonatal group (n = 38) outcome was significantly associated with Sarnat stages, presence of convulsions, severely abnormal EEG, cardiovascular failure, and multiple organ dysfunction (MOD). A bad outcome was observed in 27 cases with 14 deaths and 13 survivors. Supportive treatment was withdrawn in 14 cases with 9 subsequent deaths. In the older age group (n = 45) outcome was related to persistent coma of 24-48 h, severely abnormal EEG, cardiovascular failure, liver dysfunction and MOD. A bad outcome was found in 36 cases with 33 deaths and 3 survivors. Supportive treatment was withdrawn in 15 instances, all followed by death.

CONCLUSIONS

Overall, neonates and older patients did not differ with regard to good or bad outcome. However, in the neonatal group there were significantly more survivors with bad outcome, either overall or after withdrawal of support. Possible explanations for this difference include variability of hypoxic insult, maturational and metabolic differences, and the more compliant neonatal skull, which prevents brainstem herniation.

[Epiglottitis--a pediatric disease?]

Epiglottitis, commonly described as a paediatric disease, also occurs in adults. Early diagnosis and immediate treatment are crucial because of the rapid and possibly lethal course of upper airway obstruction due to swelling. Initial treatment consists in securing the upper airway and in antibiotic treatment. Streptococci and, especially in children, Haemophilus influenzae b are the most common bacteria. Our study focused on clinical and epidemiological changes since children started to be vaccinated against Haemophilus influenzae b in Switzerland (1992). We reviewed patient histories of 31 adults and 88 children who were hospitalised with epiglottitis at the University Hospital of Berne between 1989 and 1999. Our findings show that the incidence of epiglottitis in children, a clinically, epidemiologically and bacteriologically homogeneous disease, has dramatically decreased. Epiglottitis in adults presents as a more heterogeneous disease without change since the beginning of the vaccination programme. Due to the variety of germs it is impossible to recommend vaccination for adults against Haemophilus influenzae b.

Troponin-I for prediction of early postoperative course after pediatric cardiac surgery

OBJECTIVES

It was the aim of the study to test the prognostic value of cardiac troponin-I (cTnI) concerning the early postoperative course after pediatric cardiac surgery.

BACKGROUND

Cardiac troponin-I is a very specific and sensitive marker of myocardial damage in adults and children. As perioperative myocardial damage may be a significant factor of postoperative cardiac performance, serial cTnI values were analyzed in children undergoing open heart surgery.

METHODS

Seventy-three children undergoing elective correction of congenital heart disease including atrial and ventricular surgical manipulation were studied. Cardiac troponin-I levels were measured serially and correlated with intra- and postoperative parameters (such as doses and length of inotropic support, renal and hepatic function, duration of intubation). Patients with prolonged postoperative recovery were analyzed with special attention to the cTnI levels.

RESULTS

The cutoff point for the definition of a high and a low risk group of cTnI values was set at 25 microg/liter, 4 h after admission to the intensive care unit (ICU) and at 35 microg/liter considering the maximal value of cTnI in the first 24 h in the ICU. The results showed a highly significant correlation between the need for inotropic support, the severity of renal dysfunction and the duration of intubation in relation to the serum levels of cTnI.

CONCLUSIONS

Cardiac troponin-I serum levels after open heart surgery in children and infants 4 h after admission to the ICU allowed anticipation of the postoperative course and correlated with the incidence of significant postoperative complications.

Oral immunization with urease and Escherichia coli heat-labile enterotoxin is safe and immunogenic in Helicobacter pylori-infected adults

BACKGROUND & AIMS

Oral immunization with Helicobacter pylori urease can cure Helicobacter infection in animals. As a step toward therapeutic immunization in humans, the safety and immunogenicity of oral immunization with recombinant H. pylori urease were tested in H. pylori-infected adults.

METHODS

Twenty-six H. pylori-infected volunteers were randomized in a double-blind study to four weekly oral doses of 180, 60, or 20 mg of urease with 5 microg heat-labile enterotoxin of Escherichia coli (LT), LT alone, or placebo. Side effects and immune responses were evaluated weekly after immunization, and gastric biopsy specimens were obtained after 1 month and 6 months for histology and quantitative cultures.

RESULTS

Diarrhea was noted in 16 of 24 (66%) of the volunteers who completed the study. Antiurease serum immunoglobulin A titers increased 1. 58-fold +/- 0.37-fold and 3.66-fold +/- 1.5-fold (mean +/- SEM) after immunization with 60 and 180 mg urease, respectively, whereas no change occurred in the placebo +/- LT groups (P = 0.005). Circulating antiurease immunoglobulin A-producing cells increased in volunteers exposed to urease compared with placebo (38.9 +/- 13. 6/10(6) vs. 5.4 +/- 3.1; P = 0.018). Eradication of H. pylori infection was not observed, but urease immunization induced a significant decrease in gastric H. pylori density.

CONCLUSIONS

H. pylori urease with LT is well tolerated and immunogenic in H. pylori-infected individuals. An improved vaccine formulation may induce curative immunity.

The effects of thoracic epidural anesthesia on intraoperative visceral perfusion and metabolism

After institutional approval and informed consent, we studied the effect of epidural bupivacaine 0.5% on visceral perfusion and metabolism by using gastric mucosal tonometry in 30 patients in a placebo-controlled fashion. The maximal intramucosal pH (pHi) decrease was significantly (P < 0.001) greater in the control group (0.16 +/- 0.04) than in the thoracic epidural anesthesia (TEA) group (0.07 +/- 0.05). There were 10 patients in the control group and 2 patients in the TEA group who had evidence of gastric mucosal ischemia (pHi <7.32) at the end of the study (P< 0.01). The differences in pHi and intramucosal CO2 (PiCO2) became statistically significant between the groups after 180 and 240 min. The study data show that TEA prevents the decrease of pHi during major abdominal surgery, perhaps as an effect of stable visceral perfusion. We conclude that TEA may be a valuable method for intra- and postoperative treatment of surgical stress.

IMPLICATIONS

The present study shows that thoracic epidural anesthesia prevents a decrease of intramucosal pH during major abdominal surgery, which suggests that thoracic epidural anesthesia may be a valuable tool for the treatment of surgical stress.

Pulmonary function after one-lung ventilation in newborns: the basis for neonatal thoracoscopy

BACKGROUND

To maintain good exposure during major video-assisted thoracic surgery it is necessary to deflate completely the ipsilateral lung. However, little is known about the effects of one-lung ventilation (OLV) on pulmonary function in newborn patients.

METHODS

Ten neonatal domestic pigs with a mean age of 6+/-0.6 days were intubated and ventilated in pressure-controlled mode (inspired oxygen fraction=1.0). One-lung ventilation was maintained for 120 minutes. Serial measurements of hemodynamics and gas exchange were done before, during, and until 90 minutes after OLV. Pulmonary function testing was performed before and after OLV for each lung separately.

RESULTS

With the inspired oxygen fraction set at 1.0, arterial oxygen saturation remained stable at 100% during OLV. Venous admixture and alveolar-arterial oxygen tension gradient increased slightly from the baseline value of 2.6% +/-0.3% to 3.8%+/-0.3% during OLV (mean+/-standard error of the mean; p=0.02), and from 358+/-28 to 407+/-18 mm Hg (not significant), respectively. Both values returned to baseline during the subsequent ventilation of both lungs. Static compliance and resistance of the ventilated lung did not change. Compliance of the collapsed lung decreased after reexpansion from 0.42+/-0.07 to 0.29+/-0.06 mL x cm H2O(-1) x kg(-1), p=0.008). Resistance remained unchanged (0.22+/-0.02 versus 0.25+/-0.05 cm H2O x L(-1) x s(-1); not significant).

CONCLUSIONS

There were only minor effects on pulmonary function during and after OLV in the neonatal piglet. Alterations in gas exchange during OLV were minimal. Prolonged collapse of the lung with subsequent reexpansion was associated with a slight decrease in compliance, indicating some mild lung injury.

Mice are protected from Helicobacter pylori infection by nasal immunization with attenuated Salmonella typhimurium phoPc expressing urease A and B subunits

Live Salmonella typhimurium phoPc bacteria were tested as mucosal vaccine vectors to deliver Helicobacter pylori antigens. The genes encoding the A and B subunits of H. pylori urease were introduced into S. typhimurium phoPc and expressed under the control of a constitutive tac promoter (tac-ureAB) or a two-phase T7 expression system (cT7-ureAB). Both recombinant Salmonella strains expressed the two urease subunits in vitro and were used to nasally immunize BALB/c mice. The plasmid carrying cT7-ureAB was stably inherited by bacteria growing or persisting in the spleen, lungs, mesenteric or cervical lymph nodes, and Peyer's patches of immunized mice, while the plasmid carrying tac-ureAB was rapidly lost. Spleen and Peyer's patch CD4+ lymphocytes from mice immunized with S. typhimurium phopc cT7-ureAB proliferated in vitro in response to urease, whereas cells from mice given S. typhimurium phoPc alone did not. Splenic CD4+ cells from mice immunized with phoPc cT7-ureAB secreted gamma interferon and interleukin 10, while Peyer's patch CD4+ cells did not secrete either cytokine. Specific H. pylori anti-urease immunoglobulin G1 (IgG1) and IgG2A antibodies were detected following immunization, confirming that both Th1- and Th2-type immune responses were generated by the live vaccine. Sixty percent of the mice (9 of 15) immunized with S. typhimurium phoPc cT7-ureAB were found to be resistant to infection by H. pylori, while all mice immunized with phoPc tac-ureAB (15 of 15) or phoPc (15 of 15) were infected. Our data demonstrate that H. pylori urease delivered nasally by using a vaccine strain of S. typhimurium can trigger Th1- and Th2-type responses and induce protective immunity against Helicobacter infection.

Cloning and characterization of Helicobacter pylori succinyl CoA:acetoacetate CoA-transferase, a novel prokaryotic member of the CoA-transferase family

Sequencing of a fragment of Helicobacter pylori genome led to the identification of two open reading frames showing striking homology with Coenzyme A (CoA) transferases, enzymes catalyzing the reversible transfer of CoA from one carboxylic acid to another. The genes were present in all H. pylori strains tested by polymerase chain reaction or slot blotting but not in Campylobacter jejuni. Genes for the putative A and B subunits of H. pylori CoA-transferase were introduced into the bacterial expression vector pKK223-3 and expressed in Escherichia coli JM105 cells. Amino acid sequence comparisons, combined with measurements of enzyme activities using different CoA donors and acceptors, identified the H. pylori CoA-transferase as a succinyl CoA:acetoacetate CoA-transferase. This activity was consistently observed in different H. pylori strains. Antibodies raised against either recombinant A or B subunits recognized two distinct subunits of Mr approximately 26,000 and 24, 000 that are both necessary for H. pylori CoA-transferase function. The lack of alpha-ketoglutarate dehydrogenase and of succinyl CoA synthetase activities indicates that the generation of succinyl CoA is not mediated by the tricarboxylic acid cycle in H. pylori. We postulate the existence of an alternative pathway where the CoA-transferase is essential for energy metabolism.

Effects of one-lung ventilation on pulmonary hemodynamics and gas exchange in the newborn

For major thoracoscopic surgery, one-lung ventilation is mandatory. This is reasonably well tolerated in adults and children. The effects of one-lung ventilation on hemodynamics and gas exchange in newborns, however, are not known yet. Eight neonatal domestic pigs with a median age of 6 days (range: 3-9 days), and a mean body weight of 2.3 kg (1.7-2.8 kg) were intubated and ventilated in pressure-controlled mode (FIO2 = 1). Anesthesia was maintained with i.v. fentanyl/metomidate. After tracheotomy an endotracheal tube was positioned in the trachea, and a second tube in the left mainstem bronchus. One-lung ventilation was maintained for 120 min. Serial measurements were done before, during, and until 90 min. after one-lung ventilation. During one-lung ventilation, pulmonary artery pressure and intrapulmonary shunt increased from 15 +/- 1 to 18 +/- 1 mmHg (p = 0.004), and from 2.6 +/- 0.3 to 3.7 +/- 0.4% (p = 0.02), respectively. Arterial oxygen saturation remained unchanged at 100%. A slight increase in arterial PCO2 could easily be treated by increasing the respiratory rate. In conclusion, one-lung ventilation was not associated with major side effects in regard to hemodynamics and gas exchange in the neonatal pig.

Vigabatrin dosing during haemodialysis

The antiepileptic drug vigabatrin has shown efficacy in the treatment of patients with refractory epilepsy. Unlike many other antiepileptics it is not bound to plasma protein and mainly eliminated by the kidney. Although the therapeutic and toxic serum concentration range is not clearly defined and efficacy and toxicity are not closely correlated with the dose, factors decreasing vigabatrin elimination such as advanced age or renal failure may pose risk of untoward effects. Thus far there are no dose recommendations available for patients on haemodialysis. We report on an epileptic patient who experienced severe, partially reversible renal failure as a consequence of near-drowning. In this patient serum concentrations of vigabatrin were measured repeatedly both during haemodialysis and after partial recovery of renal function. The terminal elimination half-life in this patient was 41 hours during the period of severe renal failure (creatinine clearance < 5 ml/min). As about 60% of vigabatrin was removed from the blood pool by haemodialysis in these patients the antiepileptic should be administered after dialysis. To maintain serum concentrations in the usual range and to control seizure activity only 500 mg vigabatrin every 3 days were necessary.

Inactivation of topoisomerases affects transcription-dependent chromatin transitions in rDNA but not in a gene transcribed by RNA polymerase II

Previous studies on a chromatin reporter gene (GAL-URARIB) in yeast showed that nucleosomes were maintained but rearranged during transcription in galactose, which was consistent with local dissociation of histones at the site of the RNA polymerase. Furthermore, repositioning of nucleosomes occurred rapidly after glucose repression. Because nucleosomal disruption and transcription produce topological changes in the chromatin substrate, the effect of topoisomerase activity was tested by the insertion of GAL-URABIB in topoisomerase mutant strains. The chromatin structure was analysed by nuclease digestion and psoralen crosslinking, and compared with that of the rDNA locus. In GAL-URARIB, neither the inactivation of topoisomerases I, II or I and II generated nucleosomal loss during transcription, nor was topoisomerase activity required for repositioning of the nucleosomes after repression. In contrast, the inactivation of topoisomerase I promoted an enhanced psoralen accessibility of the transcribed rDNA, possibly because of altered supercoiling, and the inactivation of topoisomerases I and II disrupted the chromatin structure of the whole rDNA locus by redistribution of the nucleosomes. The inactivation of topoisomerase II alone had no effect. These observations substantiate a differential participation of topoisomerases in the modulation of the chromatin structures of rDNA genes and of a single copy polymerase II gene. It is suggested that topological stress in genes transcribed by RNA polymerase II might diffuse away into flanking regions.

[Therapeutic efficacy and diagnostic potential of adenosine in infants and children]

In an open study a total of 53 episodes of supraventricular reentrant tachycardia in 31 infants and children were treated with intravenous adenosine at two centers. Adenosine was given as a rapid intravenous bolus injection beginning with a dose of 0.1 mg/kg. If there was persistence of the dysrhythmia dosage was increased in 0.05 mg/kg-steps up to a maximum dose of 0.3 mg/kg if necessary. The median dose required for successful termination of the tachycardias was 0.15 mg/kg. In 26 patients with 48 episodes of regular narrow-QRS-complex tachycardia adenosine was used as the therapeutic agent of first choice. In all patients a shortlasting atrioventricular block occurred within seconds after the administration of adenosine. In 42 of 48 episodes of tachycardia (87%) the dysrhythmias were converted to a stable sinus rhythm. In six episodes (13%) recurrence of the tachycardia was observed immediately. In five children adenosine was used for diagnostic purpose: in three children with wide-QRS-complex tachycardia successful termination with adenosine proved the supraventricular origin of the dysrhythmia. In two children with suspected atrial flutter adenosine-induced atrioventricular block allowed identification of flutter waves in one patient while in the other patient no effect of adenosine was seen. Side-effects such as flush, chest-pain or abdominal pain were frequent but mild and only of a few seconds' duration. No influence of adenosine on blood pressure was noted. Only in one child with previously unknown sinus node dysfunction was a relevant electrophysiologic side effect seen: a prolonged sinus arrest with asystole of 12 seconds' duration occurred after adenosine administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute toxicity and depression of phagocytosis in vivo by liposomes: influence of lysophosphatidylcholine

Small unilamellar phospholipid vesicles (liposomes), intended as drug carriers, have recently been demonstrated to reversibly depress phagocytic activity in rats when injected in a single high dose (2g of lipid per kg body weight) as revealed by the carbon clearance test. Depression of the phagocytic function was found to vary widely depending on the lipid used [M. Brandl et al., Pharm. Pharmacol. Lett., 4 (1) 1-4, 1994]. This study has now been extended in two directions: Firstly, liposomes made of the same type of lipid but different batches of raw material were compared in terms of their influence on phagocytosis as well as for their contents of impurities. The test revealed great variability of RES suppression between different batches of hydrogenated soy PC, whereas the reproducibility of the carbon clearance test was satisfactory with liposomes made of a single batch of raw material. Thin layer chromatographic analyses of the used phosphatidylcholines (PCs) and limulus tests on lipopolysaccharides revealed lysophosphatidylcholine (lysoPC) as the only impurity which showed parallels with the observed differences in phagocytosis. Secondly by "spiking" phosphatidylcholine with increasing amounts of lysoPC the latter could be proven to enhance RES depression by liposomes in a dose-dependent manner. At the same time a strong and dose-limiting increase in acute toxicity of PC vesicles was observed with increasing contents of lysoPC. However, in cholesterol-containing vesicles lysoPC-spiking did not significantly alter their behaviour, for lysoPC contents of up to 10%. Only PC/cholesterol-vesicles containing lysoPC contents as high as 15% provoked enhanced RES depression and toxicity compared to lysoPC-free vesicles. LysoPC and cholesterol in liposomes are known to play a destabilizing and stabilizing role respectively within liposomal bilayers which might influence recognition and uptake of vesicles by macrophages and thus modulation of phagocytosis.

Latency of cathepsin B secreted by human colon carcinoma cells is not linked to secretion of cystatin C and is relieved by neutrophil elastase

The lysosomal cysteine proteinase cathepsin B is shown to be secreted by ten human colon carcinoma cell lines and to accumulate in culture media as a latent enzyme. The cell lines also secrete a physiological inhibitor of cathepsin B, cystatin C. A significant correlation was found between secretion of the latent enzyme and the inhibitor (r = 0.755, P < 0.01). The aim of the present study was to modulate the respective secretion of the two antagonists to test whether or not latency of cathepsin B was due to the concomitant secretion of the inhibitor. SW480 colon carcinoma cells were treated with the acidotropic agent ammonium chloride, phorbol 12-myristate 13-acetate, and the inflammatory cytokines TGF-beta, TNF-alpha, and IL-1 beta. Ammonium chloride significantly increased latent cathepsin B levels without affecting the constitutive secretion of cystatin C. Phorbol 12-myristate 13-acetate induced a 4- to 5-fold increase in secreted latent cathepsin B, but did not alter significantly the accumulation of cystatin C in media. The cytokines, TGF-beta, TNF-alpha, and IL-1 beta, had no major effect on the expression of these two antagonists. Latent cathepsin B released from human carcinoma cells could be efficiently activated by neutrophil elastase at neutral pH. It is concluded that latent cathepsin B is a true proenzyme rather than an enzyme-inhibitor complex. In addition, our data from neutrophil elastase activation experiments indicate that a proteolytic system for activation of the tumor cell-secreted latent enzyme may exist in vivo.

Calcium pyrophosphate dihydrate crystal deposition disease and pseudogout of the acromioclavicular joint: radiographic and pathologic features

OBJECTIVE

To correlate the radiographic and pathologic findings in calcium pyrophosphate dihydrate (CPPD) crystal deposition disease and the pseudogout syndrome in the acromioclavicular (AC) joint, a relatively infrequent, but clinically important site.

METHODS

We describe a case with a definite diagnosis of CPPD crystal deposition leading to pseudogout of the AC joint. We also identified 17 other patients with CPPD crystal deposition disease who showed intraarticular or periarticular calcification in this joint and investigated the radiographic findings in 26 AC joints in these 17 patients. We then correlated the results with the pathologic findings in 2 cadavers with AC joint manifestations of the disease.

RESULTS

Intradiscal calcification, mainly linear or punctate in configuration, was found between adjacent bony margins in 9 of 26 AC joints (35%) or between the bony margins and extending above the upper articular bony margin in 14 AC joints (54%). Two joints (8%) showed diffuse calcification within the discs between, above, and below the articular bony margins. The remaining joint (3%) had intradiscal calcification only above the upper bony margins of the AC joint. All the joints with calcifications above the articular margins had associated globular or tumor-like soft tissue masses. A pseudogout attack at the AC joint may have nonspecific shoulder pain as its presenting symptom.

CONCLUSION

CPPD crystal deposition disease leading to pseudogout syndrome of the AC joint is a clinically significant condition. We emphasize that careful assessment of the AC joint and adjacent soft tissue using intensive bright light on routine shoulder radiographs may increase the sensitivity of detecting discal and capsular calcifications in patients with pseudogout of the shoulder.

Lung mechanics and gas exchange in ventilated preterm infants during treatment of hyaline membrane disease with multiple doses of artificial surfactant (Exosurf)

Eight premature infants ventilated for hyaline membrane disease and enrolled in the OSIRIS surfactant trial were studied. Lung mechanics, gas exchange [PaCO2, arterial/alveolar PO2 ratio (a/A ratio)], and ventilator settings were determined 20 minutes before and 20 minutes after the end of Exosurf instillation, and subsequently at 12-24 hour intervals. Respiratory system compliance (Crs) and resistance (Rrs) were measured by means of the single breath occlusion method. After surfactant instillation there were no significant immediate changes in PaCO2 (36 vs. 37 mmHg), a/A ratio (0.23 vs. 0.20), Crs (0.32 vs. 0.31 mL/cm H2O/kg), and Rrs (0.11 vs. 0.16 cmH2O/mL/s) (pooled data of 18 measurement pairs). During the clinical course, mean a/A ratio improved significantly each time from 0.17 (time 0) to 0.29 (time 12-13 hours), to 0.39 (time 24-36 hours) and to 0.60 (time 48-61 hours), although mean airway pressure was reduced substantially. Mean Crs increased significantly from 0.28 mL/cmH2O/kg (time 0) to 0.38 (time 12-13 hours), to 0.37 (time 24-38 hours), and to 0.52 (time 48-61 hours), whereas mean Rrs increased from 0.10 cm H2O/mL/s (time 0) to 0.11 (time 12-13 hours), to 0.13 (time 24-36 hours) and to (time 48-61 hours) with no overall significance. A highly significant correlation was found between Crs and a/A ratio (r = 0.698, P less than 0.001). We conclude that Exosurf does not induce immediate changes in oxygenation as does the instillation of (modified) natural surfactant preparations. However, after 12 and 24 hours of treatment oxygenation and Crs improve significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

[Prospective comparison of miconazole gel and nystatin suspension in the treatment of oral candidiasis]

Miconazole gel and nystatin suspension were compared in a prospective randomised therapeutic trial including 51 cases of oral candidiasis in hospitalised pediatric patients. Clinical evaluations, microscopic examinations and adequate cultures were the basis for diagnosis and follow-up over 3-4 weeks. Miconazole oral gel therapy resulted in an optimal cure rate of 100% and in a relapse rate of only 4%, whereas for nystatin suspension these values were 75% and 22% respectively. However, apart from producing a better effect compared to nystatin suspension, miconazole gel also involved a higher rate of minor gastrointestinal side effects and worse acceptance. Older children often tolerated poorly the sweet taste of miconazole gel. It is recommended that the gel form of the potent antimycotic agent miconazole be mainly used in infants and young children.

Selenium requirements in patients with inborn errors of amino acid metabolism and selenium deficiency

The diets of 5 patients with phenylketonuria of maple-syrup-urine disease were supplemented with yeast which was rich in selenium. For 120 days the patients received 45 micrograms Se/day to increase the Se content of their diets to 10--12 ng Se/Kjoule. Before supplementation the selenium content of serum (5--15 ng/ml) and whole blood (10--27 ng/ml), and the activity of the erythrocyte glutathione peroxidase (0.19--2.69 U37/g Hb), amounted to only 10--20% of normal. The serum selenium content reached normal values within 4 weeks of supplementation, followed by normalisation of the selenium content of whole blood within 4--8 weeks. Restoration of the activity of erythrocyte glutathione peroxidase took 9 to 15 weeks--the red cell life span. There was a significant positive correlation between the selenium content of the erythrocytes and the activity of erythrocyte glutathione peroxidase.