Different nutrient receptors varied in triggering germination of Bacillus subtilis spores with a pressure of 150 MPa, the GerA receptor being more responsive than the GerB receptor and even more responsive than the GerK receptor. This hierarchy in receptor responsiveness to pressure was the same as receptor responsiveness to a mixture of nutrients. The levels of nutrient receptors influenced rates of pressure germination, since the GerA receptor is more abundant than the GerB receptor and elevated levels of individual receptors increased spore germination by 150 MPa of pressure. However, GerB receptor variants with relaxed specificity for nutrient germinants responded as well as the GerA receptor to this pressure. Spores lacking dipicolinic acid did not germinate with this pressure, and pressure activation of the GerA receptor required covalent addition of diacylglycerol. However, pressure activation of the GerB and GerK receptors displayed only a partial (GerB) or no (GerK) diacylglycerylation requirement. These effects of receptor diacylglycerylation on pressure germination are similar to those on nutrient germination. Wild-type spores prepared at higher temperatures germinated more rapidly with a pressure of 150 MPa than spores prepared at lower temperatures; this was also true for spores with only one receptor, but receptor levels did not increase in spores made at higher temperatures. Changes in inner membrane unsaturated fatty acid levels, lethal treatment with oxidizing agents, or exposure to chemicals that inhibit nutrient germination had no major effect on spore germination by 150 MPa of pressure, except for strong inhibition by HgCl 2 .

Aims: To elucidate factors influencing the sensitivity of Bacillus subtilis spores to DNA damaging chemicals. Methods and Results: Wild-type spores of B. subtilis made at lower temperatures were more sensitive to the DNA damaging chemicals formaldehyde and nitrous acid than were spores made at higher temperatures, but this was not the case with the DNA alkylating agents ethylmethanesulphonate and methylmethanesulphonate. Spores lacking most DNA protective a ⁄ b-type small, acid-soluble proteins (termed a ) b) spores) made at lower temperatures were also more sensitive to killing through DNA damage by hydrogen peroxide than were a ) b ) spores made at higher temperatures. The spore coat, whose composition varies significantly with sporulation temperature, played only a minor role in spore resistance to these DNA damaging agents. Spores made at lower temperatures exhibited higher permeability to the methylamine and germinated more rapidly with the surfactant dodecylamine than did spores made at higher temperatures. Treatment of spores with the oxidizing agent cumene hydroperoxide sensitized the surviving spores to all these DNA damaging agents. The fatty acid composition of the inner membrane of spores made at different temperatures differed significantly, but levels of unsaturated fatty acids in the inner membrane did not influence spore resistance to DNA damaging agents or the sensitization to such agents by prior treatment with cumene hydroperoxide.Conclusions: The higher rates of methylamine permeation across the inner membrane of spores made at lower temperatures and the greater sensitivity of wild-type spores made at lower temperatures to formaldehyde and nitrous acid and of a ) b ) spores made at lower temperatures to hydrogen peroxide, all agents that must pass through the spore's inner membrane to damage DNA in the spore core, suggest that the permeability of the inner membrane is a significant factor influencing spore sensitivity to these agents. The sensitization of spores to DNA damaging chemicals by pretreatment with an oxidizing agent, a treatment that increases the permeability of the spore's inner membrane, and the more rapid dodecylamine germination of spores made at lower temperatures are consistent with this suggestion. Significance and Impact of the Study: The results in this communication provide new insight into the factors that influence the resistance of spores of Bacillus species to chemicals that kill spores by damaging spore DNA.

Aims: To determine the mechanism of action of inhibitors of the germination of spores of Bacillus species, and where these inhibitors act in the germination process. Methods and Results: Spores of various Bacillus species are significant agents of food spoilage and foodborne disease, and inhibition of spore germination is a potential means of reducing such problems. Germination of the following spores was studied: (i) wild-type B. subtilis spores; (ii) B. subtilis spores with a nutrient receptor variant allowing recognition of a novel germinant; (iii) B. subtilis spores with elevated levels of either the variant nutrient receptor or its wild-type allele; (iv) B. subtilis spores lacking all nutrient receptors and (v) wild-type B. megaterium spores. Spores were germinated with a variety of nutrient germinants, Ca 2+ -dipicolinic acid (DPA) and dodecylamine for B. subtilis spores, and KBr for B. megaterium spores. Compounds tested as inhibitors of germination included alkyl alcohols, a phenol derivative, a fatty acid, ion channel blockers, enzyme inhibitors and several other compounds. Assays used to assess rates of spore germination monitored: (i) the fall in optical density at 600 nm of spore suspensions; (ii) the release of the dormant spore's large depot of DPA; (iii) hydrolysis of the dormant spore's peptidoglycan cortex and (iv) generation of CFU from spores that lacked all nutrient receptors. The results with B. subtilis spores allowed the assignment of inhibitory compounds into two general groups: (i) those that inhibited the action of, or response to, one nutrient receptor and (ii) those that blocked the action of, or response to, several or all of the nutrient receptors. Some of the compounds in groups 1 and 2 also blocked action of at least one cortex lytic enzyme, however, this does not appear to be the primary site of their action in inhibiting spore germination. The inhibitors had rather different effects on germination of B. subtilis spores with nutrients or non-nutrients, consistent with previous work indicating that germination of B. subtilis spores by nonnutrients does not involve the spore's nutrient receptors. In particular, none of the compounds tested inhibited spore germination with dodecylamine, and only three compounds inhibited Ca 2+ -DPA germination. In contrast, all compounds had very similar effects on the germination of B. megaterium spores with either glucose or KBr. The effects of the inhibitors tested on spores of both Bacillus species were largely reversible. Conclusions: This work indicates that inhibitors of B. subtilis spore germination fall into two classes: (i) compounds (most alkyl alcohols, N-ethylmaleimide, nifedipine, phenols, potassium sorbate) that inhibit the action of, or response to, primarily one nutrient receptor and (ii) compounds [amiloride, HgCl 2 , octanoic acid, octanol, phenylmethylsulphonylfluoride (PMSF), quinine, tetracaine, tosyl-L L-arginine methyl ester, trifluoperazine] that inhibit the action of, or response to, several nutrient receptors. Action of th...

Moral distress is prevalent in the neonatal intensive care unit (NICU), where decisions regarding end-of-life care, periviable resuscitation, and medical futility are common. Due to its origins in the nursing literature, moral distress has primarily been reported among bedside nurses in relation to the hierarchy of the medical team. However, it is increasingly recognized that moral distress may exist in different forms than initially described and that healthcare professions outside of nursing experience it. Advances in medical technology have allowed the smallest, sickest neonates to survive. The treatment for critically ill infants is no longer simply limited by the capability of medical technology but also by moral and ethical boundaries of what is right for a given child and family. Shared decision-making and the zone of parental discretion can inform and challenge the medical team to balance the complexities of patient autonomy against harm and suffering. Limited ability to prognosticate and uncertainty in outcomes add to the challenges faced with ethical dilemmas. While this does not necessarily equate to moral distress, subjective views of quality of life and personal values in these situations can lead to moral distress if the plans of care and the validity of each path are not fully explored. Differences in opinions and approaches between members of the medical team can strain relationships and affect each individual differently. It is unclear how the various types of moral distress uniquely impact each profession and their role in the distinctively challenging decisions made in the NICU environment. The purpose of this review is to describe moral distress and the situations that give rise to it in the NICU, ways in which various members of the medical team experience it, how it impacts care delivery, and approaches to address it.