Engineered Bacteria for Enhanced Radiotherapy against Breast Carcinoma

Radiotherapy is widely applied for multiple malignant tumors ablation in the clinic. However, redundant doses of X-rays might destroy normal tissue in the periphery of tumor sites. Here, we developed an integrated nanosystem (Bac@BNP) composed of engineered bacteria (Bac) and Bi₂S₃ nanoparticles (BNPs) for sensitizing radiotherapy. Bac could target and colonize in tumor sites alternatively, which overexpressed cytolysin A (ClyA) protein to regulate the cell cycle from a radioresistant phase to a radiosensitive phase. Simultaneously, peptide-modified BNPs, as a radiosensitizer with a high-Z element, was released from the surface of Bac owing to the matrix metalloproteinase-2 (MMP-2) response in the tumor microenvironment. Under X-ray irradiation, BNPs could enhance the radiotherapy sensitivity by triggering the intracellular generation of reactive oxygen species (ROS), coupled with DNA damage. In this constructed nanosystem, the combination of Bac@BNP and X-ray irradiation led to significant suppression of breast carcinoma in murine models with reduced side effects.

The Use of Deceased Controls in Epidemiologic Research: A Systematic Review

Scholarly debate on the use of deceased controls in epidemiologic research continues. This systematic review examined published epidemiologic research using deceased persons as a control group. A systematic search of 5 major biomedical literature databases (MEDLINE, CINAHL, PsycINFO, Scopus, and EMBASE) was conducted, using variations of the search terms "deceased" and "controls" to identify relevant peer-reviewed journal articles. Information was sought on study design, rationale for using deceased controls, application of theoretical principles of control selection, and discussion of the use of deceased controls. The review identified 134 studies using deceased controls published in English between 1978 and 2015. Common health outcomes under investigation included cancer (n = 31; 23.1%), nervous system diseases (n = 26; 19.4%), and injury and other external causes (n = 22; 16.4%). The majority of studies used deceased controls for comparison with deceased cases (n = 95; 70.9%). Investigators rarely presented their rationale for control selection (n = 25/134; 18.7%); however, common reasons included comparability of information on exposures, lack of appropriate controls from other sources, and counteracting bias associated with living controls. Comparable accuracy was the most frequently observed principle of control selection (n = 92; 68.7%). This review highlights the breadth of research using deceased controls and indicates their appropriateness in studies using deceased cases.

Infectious causes of sudden infant death syndrome

Investigators have long suspected the role of infection in sudden infant death syndrome (SIDS). Evidence of infectious associations with SIDS is accentuated through the presence of markers of infection and inflammation on autopsy of SIDS infants and isolates of some bacteria and viruses. Several observational studies have looked into the relation between seasonality and incidence of SIDS, which often showed a winter peak. These all may suggest an infectious aetiology of SIDS. In this review we have summarised the current literature on infectious aetiologies of SIDS by looking at viral, bacterial, genetic and environmental factors which are believed to be associated with SIDS.

Maternal and perinatal risk factors for SIDS: a novel analysis utilizing pregnancy outcome data

A number of maternal and perinatal factors to increase an infant's risk of sudden infant death syndrome (SIDS) have been found in past investigations. We analysed data for potential SIDS risk factors including the presence of complications or conditions considered as detrimental to the infant's or mother's health. The data for 118 SIDS cases and 227 matched controls were obtained from a state pregnancy outcome unit. SIDS was found to be significantly more common in cases where the infant's mother was not in a relationship (i.e. divorced, separated or never married) (p = 0.005), if the infant was not the first born (p = 0.0001) and when the mother resided in a socioeconomically disadvantaged area (p = 0.03).

CONCLUSION

Overall, this SIDS cohort appears to display classical SIDS associations, and our findings are consistent with those from other regions. This novel epidemiological tool opens the way for a national Australia-wide study using pregnancy outcome data collected by the individual states and could be helpful in assessing maternal and fetal risk factors for other paediatric medical conditions.

Occurrence and characteristics of virulence genes of Escherichia coli strains isolated from healthy dairy cows in Inner Mongolia, China

Virulence genes of Escherichia coli (E. coli) isolates from healthy dairy cows were identified and characterized by a multiplex PCR assay and serogrouping test. The results showed that among the target genes, eaeA was most frequently detected, accounting for 22.11% (67/303) in all strains from 101 cows. For categorization of E. coli, aEPEC was the category with widest distribution detected in 55 (18.15%) strains from 22 cattle. All of 84 PCR-positive strains belonged to 14 O serogroups, and O149 (25.00%) was most common identified, followed by O2 (17.86%), O8 (11.90%) and O103 (9.52%) with relatively high prevalence.

A possible murine model for investigation of pathogenesis of sudden infant death syndrome

Several studies have indicated a possible causative role of toxigenic bacteria in sudden infant death syndrome (SIDS). This study examined the effect of toxigenic E. coli on pregnant and infant mice to determine if these animals could be used as a model for SIDS pathogenesis. Strains of E. coli from the intestinal contents of infants who have died of SIDS or other causes and from the faeces of healthy infants were collected over a broad time scale. The isolates were tested for their ability to produce then known toxins of E. coli and were serotyped (O and H antigens). Certain serotypes (e.g. O1:H- and O25:H1) emerged significantly more frequently from cases of SIDS than from healthy infants and isolates of these types were generally toxigenic in Vero-cell cultures but whose verotoxicity was not related to classical Shiga or other known toxins. This mouse model was developed to test the effects of these toxigenic and also non-toxigenic strains. Four apparently healthy pups aged between 17 and 21 days died unobserved overnight but no pups of the 54 control mice died suddenly (P = 0.0247, Fisher's exact test). These were considered to represent sudden unexpected deaths. Pathological effects compatible with those in SIDS were observed in mouse pups exposed to toxigenic strains indicating this model may be suitable for further study into the pathogenesis of unexpected deaths in infancy. Providing an animal model of SIDS would promote a much better avenue for studying the pathogenesis of this enigmatic condition.

A perspective on SIDS pathogenesis. the hypotheses: plausibility and evidence

Several theories of the underlying mechanisms of Sudden Infant Death Syndrome (SIDS) have been proposed. These theories have born relatively narrow beach-head research programs attracting generous research funding sustained for many years at expense to the public purse. This perspective endeavors to critically examine the evidence and bases of these theories and determine their plausibility; and questions whether or not a safe and reasoned hypothesis lies at their foundation. The Opinion sets specific criteria by asking the following questions: 1. Does the hypothesis take into account the key pathological findings in SIDS? 2. Is the hypothesis congruent with the key epidemiological risk factors? 3. Does it link 1 and 2? Falling short of any one of these answers, by inference, would imply insufficient grounds for a sustainable hypothesis. Some of the hypotheses overlap, for instance, notional respiratory failure may encompass apnea, prone sleep position, and asphyxia which may be seen to be linked to co-sleeping. For the purposes of this paper, each element will be assessed on the above criteria.

Critical diaphragm failure in sudden infant death syndrome

Sudden infant death syndrome (SIDS) is the leading cause of death in infants between the ages of 1 and 12 months in developed countries. SIDS is by definition a diagnosis of exclusion, and its mechanism of action is unknown. The SIDS-Critical Diaphragm Failure (CDF) hypothesis postulates that the cause of death in SIDS is respiratory failure caused by CDF. Four principal risk factors contribute to CDF in young infants: undeveloped respiratory muscles, non-lethal infections, prone resting position, and REM sleep. Even relatively minor infections can cause an acute and significant reduction in diaphragm force generation capacity that in conjunction with other risk factors can precipitate CDF. CDF-induced acute muscle weakness leaves few, if any pathological marks on the affected tissue.Understanding the underlying mechanism of SIDS may help in formulating new approaches to child care that can help to further reduce the incidence of SIDS.

Serotypes of Escherichia coli in sudden infant death syndrome

AIM

To examine the diversity of Escherichia coli serotypes found in the intestinal contents of infants who died of Sudden Infant Death Syndrome (SIDS) compared with that in comparison infants.

METHODS AND RESULTS

Over the 3-year period, 1989-1991, in South Australia and Victoria (Australia), a total of 687 E. coli isolates from 231 patients with SIDS (348 isolates), 98 infants who had died from other causes (144 isolates) and 160 healthy infants (195 isolates) were studied. The isolates from patients with SIDS were found to represent 119 different serotypes; the isolates from 'other cause' infants represent 97 different serotypes; and the isolates from healthy infants represent 117 different serotypes. The seven common serotypes isolated most frequently from infants with SIDS belonged to those associated with extra-intestinal infections in humans. Compared to healthy infants (6%), these were found in significantly higher proportions among infants who died of other causes (13%, P < 0.05) or infants with SIDS (18.7%, P = 0.0002).

CONCLUSIONS

Despite these sources yielding a wide variety of serotypes of E. coli, a pattern of certain potential pathotypes of E. coli being associated with SIDS is apparent.

SIGNIFICANCE AND IMPACT OF THE STUDY

While SIDS remains one of the most important diagnoses of postneonatal death, its causes are still unexplained. If E. coli has a role in the pathogenesis of SIDS (as suggested by the pathotypes identified on the basis of serotype), further studies may reveal novel virulence factors that may clarify the role of this bacterium in SIDS.