Gut Dysbiosis With Bacilli Dominance and Accumulation of Fermentation Products Precedes Late-onset Sepsis in Preterm Infants

BACKGROUND

Gut dysbiosis has been suggested as a major risk factor for the development of late-onset sepsis (LOS), a main cause of mortality and morbidity in preterm infants. We aimed to assess specific signatures of the gut microbiome, including metabolic profiles, in preterm infants <34 weeks of gestation preceding LOS.

METHODS

In a single-center cohort, fecal samples from preterm infants were prospectively collected during the period of highest vulnerability for LOS (days 7, 14, and 21 of life). Following 16S rRNA gene profiling, we assessed microbial community function using microbial metabolic network modeling. Data were adjusted for gestational age and use of probiotics.

RESULTS

We studied stool samples from 71 preterm infants with LOS and 164 unaffected controls (no LOS/necrotizing enterocolitis). In most cases, the bacteria isolated in diagnostic blood culture corresponded to the genera in the gut microbiome. LOS cases had a decelerated development of microbial diversity. Before onset of disease, LOS cases had specific gut microbiome signatures with higher abundance of Bacilli (specifically coagulase-negative Staphylococci) and a lack of anaerobic bacteria. In silico modeling of bacterial community metabolism suggested accumulation of the fermentation products ethanol and formic acid in LOS cases before the onset of disease.

CONCLUSIONS

Intestinal dysbiosis preceding LOS is characterized by an accumulation of Bacilli and their fermentation products and a paucity of anaerobic bacteria. Early microbiome and metabolic patterns may become a valuable biomarker to guide individualized prevention strategies of LOS in highly vulnerable populations.

Granulocytic myeloid-derived suppressor cells (GR-MDSC) accumulate in cord blood of preterm infants and remain elevated during the neonatal period

Preterm delivery is the leading cause of perinatal morbidity and mortality. Among the most important complications in preterm infants are peri- or postnatal infections. Myeloid-derived suppressor cells (MDSC) are myeloid cells with suppressive activity on other immune cells. Emerging evidence suggests that granulocytic MDSC (GR-MDSC) play a pivotal role in mediating maternal-fetal tolerance. The role of MDSC for postnatal immune-regulation in neonates is incompletely understood. Until the present time, nothing was known about expression of MDSC in preterm infants. In the present pilot study, we quantified GR-MDSC counts in cord blood and peripheral blood of preterm infants born between 23 + 0 and 36 + 6 weeks of gestation (WOG) during the first 3 months of life and analysed the effect of perinatal infections. We show that GR-MDSC are increased in cord blood independent of gestational age and remain elevated in peripheral blood of preterm infants during the neonatal period. After day 28 they drop to nearly adult levels. In case of perinatal or postnatal infection, GR-MDSC accumulate further and correlate with inflammatory markers C-reactive protein (CRP) and white blood cell counts (WBC). Our results point towards a role of GR-MDSC for immune-regulation in preterm infants and render them as a potential target for cell-based therapy of infections in these patients.

A bird pollinator shows positive frequency dependence and constancy of species choice in natural plant communities

Animal pollinators mediate reproduction of many plant species. Foraging theory suggests that animal pollinators exhibit preferences for common plant species in natural communities (positive frequency-dependent foraging) and temporary single-species specialization (flower constancy) during foraging bouts. Positive frequency dependence may favor common plant species; flower constancy may enhance conspecific pollen transfer particularly in rare plant species. Previous experimental studies suggest that avian pollinators are unlikely to exhibit these behaviors. We studied foraging behavior of Cape Sugarbirds (Promerops cafer), the main avian pollinator of many Protea species, using focal-plant and focal-bird sampling, assisted by high-resolution maps of the spatiotemporal distribution of Protea individuals and their flowering status. We found that Sugarbird's visitation preference increased with species' relative floral abundance, and that individual Sugarbirds tended to visit single species in sequence. Flower constancy during foraging bouts was significantly higher than expected from random plant-animal encounters at the scale of pollinator movements. Positive frequency dependence may favor the reproduction of abundant plant species while flower constancy may be particularly important for rare plant species. This first simultaneous study of both behaviors in a natural plant-pollinator system shows that bird pollinators exhibit both types of behavior and, in this way, possibly influence plant community structure.

Regulatory T cell frequencies are increased in preterm infants with clinical early-onset sepsis

The predisposition of preterm neonates to invasive infection is, as yet, incompletely understood. Regulatory T cells (Tregs ) are potential candidates for the ontogenetic control of immune activation and tissue damage in preterm infants. It was the aim of our study to characterize lymphocyte subsets and in particular CD4(+) CD25(+) forkhead box protein 3 (FoxP3)(+) Tregs in peripheral blood of well-phenotyped preterm infants (n = 117; 23 + 0 - 36 + 6 weeks of gestational age) in the first 3 days of life in comparison to term infants and adults. We demonstrated a negative correlation of Treg frequencies and gestational age. Tregs were increased in blood samples of preterm infants compared to term infants and adults. Notably, we found an increased Treg frequency in preterm infants with clinical early-onset sepsis while cause of preterm delivery, e.g. chorioamnionitis, did not affect Treg frequencies. Our data suggest that Tregs apparently play an important role in maintaining maternal-fetal tolerance, which turns into an increased sepsis risk after preterm delivery. Functional analyses are needed in order to elucidate whether Tregs have potential as future target for diagnostics and therapeutics.

[The inhalation versus systemic prevention of pneumonitis during thoracic irradiation]

BACKGROUND

Pneumonitis is a typical subacute reaction of healthy bronchial tissue to thoracic irradiation. The purpose of the present trial was to show whether prophylactic application of steroids in the course of and following radiotherapy would reduce the incidence of pneumonitis.

PATIENTS AND METHODS

Fifty-seven patients receiving thoracic irradiation for bronchial carcinoma were assigned to 2 therapeutic groups; half of the patients were given 10 mg of oral prednisolone per day, while the other half received daily inhalative beclomethasone. All patients were evaluated for radiographic signs of pneumonitis. Thirty-two patients received additional investigations for pulmonary diffusion capacity of carbon monoxide.

RESULTS

The overall incidence of pneumonitis was 17.6% (10/57 patients). Neither total radiation dose nor mode of fractionation did significantly contribute to the incidence of pneumonitis. Those patients showing a pulmonary diffusion capacity for carbon monoxide of less than 60% prior to radiotherapy had a significantly higher risk of developing pneumonitis (4/7) than patients with a higher diffusion capacity (3/25, p = 0.026). In follow-up period we did not see significant changes in diffusion capacity neither with patients who developed pneumonitis nor with those patients showing no evidence of pulmonary injury. Comparing the chest X-ray there were less radiographic changes consistent with pneumonitis in the inhalative beclomethasone (2/28) than in the oral prednisolone group (8/29, p = 0.045).

DISCUSSION

In order to reduce the incidence of pneumonitis in patients receiving thoracic irradiation we support a continuous application of steroids in the course of and following radiotherapy. The inhalative use of beclomethasone has proved to be superior to oral prednisolone due to better local efficacy and decreased unwanted side effects.

Functional analysis of DNA bending and unwinding by the high mobility group domain of LEF-1

LEF-1 (lymphoid enhancer-binding factor 1) is a cell type-specific member of the family of high mobility group (HMG) domain proteins that recognizes a specific nucleotide sequence in the T cell receptor (TCR) alpha enhancer. In this study, we extend the analysis of the DNA-binding properties of LEF-1 and examine their contributions to the regulation of gene expression. We find that LEF-1, like nonspecific HMG-domain proteins, can interact with irregular DNA structures such as four-way junctions, albeit with lower efficiency than with specific duplex DNA. We also show by a phasing analysis that the LEF-induced DNA bend is directed toward the major groove. In addition, we find that the interaction of LEF-1 with a specific binding site in circular DNA changes the linking number of DNA and unwinds the double helix. Finally, we identified two nucleotides in the LEF-1-binding site that are important for protein-induced DNA bending. Mutations of these nucleotides decrease both the extent of DNA bending and the transactivation of the TCR alpha enhancer by LEF-1, suggesting a contribution of protein-induced DNA bending to the function of TCR alpha enhancer.

Early intervention and aggressive management of infected median sternotomy incision: a review of 2242 open-heart procedures

Infected median sternotomy following open-heart surgery is a devastating complication with an incidence of 0.4 to 5 per cent and mortality as high as 80 per cent. Management varies from irrigation, debridement, closure with muscle, and skin flaps. We present our experience of early intervention and aggressive single-stage operative management. A retrospective chart review of all open-heart surgery patients was conducted from September 1984 through September 1994. Of the 2242 patients, 52 had infected median sternotomy incisions (2.3% incidence). The mean length of stay for reconstructive procedures was 18 days. The median interval to detection was 15 days, whereas the median interval to intervention was 4 days. There were five (6.8%) failed procedures and nine (12.3%) staged procedures. There were six deaths (11.5% incidence), one prior to receiving operative intervention. There was one false aneurysm. Single-stage reconstruction is safe, with results better than multistage procedures. It may be safely performed with a high success rate (93%). Early recognition and intervention significantly decreases length of stay.

Distinct DNA-binding properties of the high mobility group domain of murine and human SRY sex-determining factors

The mammalian sex-determining gene SRY (sex-determining region on Y chromosome) encodes a member of the high mobility group (HMG) family of regulatory proteins. The HMG domain of the SRY protein represents a DNA binding motif that displays rather unusually weak evolutionary conservation of amino acids between human and mouse sequences. Together with the previous finding that the human (h) SRY gene is unable to induce a male phenotype in genetically female transgenic mice, these observations raise questions concerning the DNA binding properties of SRY proteins. Here, we present data that indicate that the DNA binding and bending properties of the HMG domains of murine (m) SRY and hSRY differ from each other. In comparison, mSRY shows more-extensive major-groove contacts with DNA and a higher specificity of sequence recognition than hSRY. Moreover, the extent of protein-induced DNA bending differs from the HMG domains of hSRY and mSRY. These differences in DNA binding by hSRY and mSRY may, in part, account for the functional differences observed with these gene products.

HMG domain proteins: architectural elements in the assembly of nucleoprotein structures

The high-mobility group (HMG) domain is a DNA-binding motif that is shared abundant non-histone components of chromatin and by specific regulators of transcription and cell differentiation. The HMG family of proteins comprises members with multiple HMG domains that bind DNA with low sequence specificity, and members with single HMG domains that recognize specific nucleotide sequences. Common properties of HMG domain proteins include interaction with the minor groove of the DNA helix, binding to irregular DNA structures, and the capacity to modulate DNA structure by bending. DNA bending induced by the HMG domain can facilitate the formation of higher-order nucleoprotein complexes, suggesting that HMG domain proteins may have an architectural role in assembling such complexes.

Bromocriptine in the treatment of carcinoma of the cervix: a phase II trial

Twenty patients with advanced carcinoma of the uterine cervix were treated for at least 3 months with 5 mg bromocriptine daily. No remissions were found (95% confidence limits, 0-17%), neither among normo- nor among hyperprolactinemic patients. Twelve had stable disease for 2-9 months with a median of 3 months. The results of this study does not support the hypothesis that bromocriptine possesses any antitumor effect in cancer of the uterine cervix.

Transport patterns and complications in an isolated Alaska practice

This study reviews the patterns of transport and complications that occurred in 169 cases of transporting patients over a four-year period for a small, isolated Alaskan community in which the physicians as a matter of policy attempted to avoid heroic emergency surgery. Case descriptions are included describing transport-related complications and mortality and morbidity of patients transferred. A low incidence of mortality and relatively little long-term morbidity was experienced, supporting the feasibility of transferring severely ill patients rather than attempting heroic surgery under marginal circumstances. Although the lack of comparable studies limits the usefulness of these findings in assessing the overall quality of care, appropriate utilization of transport as an extension of the physician's capabilities resulted in a low incidence of complications during the study period.