A Randomized Control Trial of Meditation for Mothers Pumping Breastmilk for Preterm Infants

OBJECTIVE

 Mothers of preterm infants face unique challenges in establishing milk supply. We hypothesized that daily meditation practice while pumping would increase milk volume.

STUDY DESIGN

 This was a randomized control trial examining the effect of meditation on the breastmilk supply of women delivering preterm infants. The meditation group engaged in daily use of a mindfulness-focused meditation app in addition to routine lactation support. The primary outcome was mean breastmilk volume on the infant's nineth day of life. Secondary outcomes included use of lactation-promoting behaviors, continuation of breastfeeding, and measures of mental health and breastfeeding self-efficacy by validated questionnaires. In addition to the intention to treat analysis, a per protocol analysis examined the association of frequent meditation with these breastfeeding and mental health outcomes.

RESULTS

 A total of 60 women were analyzed. Mean milk volume was 647.1 ± 467.8 mL in the meditation group and 514.9 ± 393.5 mL in the routine care group (p = 0.27). Median number of pumping sessions was 7 (interquartile range [IQR] 5-8) in the meditation group, compared to 6 (IQR 4-7) in the routine care group (p = 0.11). Other lactation-promoting behaviors, breastfeeding continuation, and questionnaire scores were similar.Adjusting for confounders, we found an increase in breastmilk production of 223.2 mL (95% CI 98.8-347.5, p = 0.001) and in pumping episodes by 0.93 (95% CI 0.16-1.70, p = 0.020) associated with frequent meditation. Skin-to-skin contact was increased to 100% (p = 0.006) among women who meditated seven or more times. Adjusted odds of a clinically significant Edinburgh Postnatal Depression Scale score of >9 was 0.057 (95% CI 0.0014-0.711, p = 0.023) with frequent meditation.

CONCLUSION

 Breastmilk production was similar in mothers practicing meditation compared to those receiving routine lactation support. For women engaging in frequent mediation, there may be an effect in establishing breastmilk supply and reduction of depression symptoms.

KEY POINTS

· Breastmilk is not increased for neonatal intensive care unit (NICU) moms asked to engage in meditation.. · Maternal mental health is not improved among NICU moms asked to meditate.. · However, higher-frequency meditation is associated with increased milk volume and lower odds of high scores on depression screening..

Laryngeal mask use during neonatal resuscitation at birth: A United States-based survey of neonatal resuscitation program providers and instructors

Aim

Neonatal resuscitation guidelines promote the laryngeal mask (LM) interface for positive pressure ventilation (PPV), but little is known about how the LM is used among Neonatal Resuscitation Program (NRP) Providers and Instructors. The study aim was to characterize the training, experience, confidence, and perspectives of NRP Providers and Instructors regarding LM use during neonatal resuscitation at birth.

Methods

A voluntary anonymous survey was emailed to all NRP Providers and Instructors. Survey items addressed training, experience, confidence, and barriers for LM use during resuscitation. Associations between respondent characteristics and outcomes of both LM experience and confidence were assessed using logistic regression.

Results

Between 11/7/22-12/12/22, there were 5,809 survey respondents: 68% were NRP Providers, 55% were nurses, and 87% worked in a hospital setting. Of these, 12% had ever placed a LM during newborn resuscitation, and 25% felt very or completely confident using a LM. In logistic regression, clinical or simulated hands-on training, NRP Instructor role, professional role, and practice setting were all associated with both LM experience and confidence.The three most frequently identified barriers to LM use were insufficient experience (46%), preference for other interfaces (25%), and failure to consider the LM during resuscitation (21%). One-third (33%) reported that LMs are not available where they resuscitate newborns.

Conclusion

Few NRP providers and instructors use the LM during neonatal resuscitation. Strategies to increase LM use include hands-on clinical training, outreach promoting the advantages of the LM compared to other interfaces, and improving availability of the LM in delivery settings.

Impact of Early Fortification in Very Low Birth Weight Infants on the Incidence of Malnutrition During a Trophamine Shortage

OBJECTIVE

The devastation of pharmaceutical production facilities from Hurricane Maria caused a national shortage of parenteral amino acids in October 2017. Our institution decreased trophamine in very low birth weight (VLBW) infants and initiated human milk fortification at a lower feeding volume to increase enteral protein intake more quickly. The objective of this study was to assess how protein management during the shortage period affected the incidence of malnutrition.

METHODS

This was a retrospective cohort study of infants admitted to 2 neonatal intensive care units from June 1, 2017 to May 31, 2018. Infants between 23 and 32 weeks' gestation were included in this study. The primary outcome was the incidence of malnutrition at 14 days, defined as a z score decline of ≥0.8 SDs, in the pre-shortage period compared with the shortage period. Clinical data regarding adverse effects associated with early fortification and pharmacy costs were recorded.

RESULTS

There were 68 infants prior to and 65 during the shortage who met inclusion criteria. There was no difference in malnutrition between the pre-shortage and shortage groups; however, a significant increase in malnutrition was observed in infants who did not receive early fortification during the shortage. No difference in time to full enteral feeds or necrotizing enterocolitis was observed with early fortification.

CONCLUSIONS

Early fortification in VLBW infants receiving less trophamine during the shortage was not associated with an increase in malnutrition. Restricting trophamine in neonates during the shortage allowed for distribution to other critically ill patients.

Systematic review and network meta-analysis with individual participant data on cord management at preterm birth (iCOMP): study protocol

INTRODUCTION

Timing of cord clamping and other cord management strategies may improve outcomes at preterm birth. However, it is unclear whether benefits apply to all preterm subgroups. Previous and current trials compare various policies, including time-based or physiology-based deferred cord clamping, and cord milking. Individual participant data (IPD) enable exploration of different strategies within subgroups. Network meta-analysis (NMA) enables comparison and ranking of all available interventions using a combination of direct and indirect comparisons.

OBJECTIVES

(1) To evaluate the effectiveness of cord management strategies for preterm infants on neonatal mortality and morbidity overall and for different participant characteristics using IPD meta-analysis. (2) To evaluate and rank the effect of different cord management strategies for preterm births on mortality and other key outcomes using NMA.

METHODS AND ANALYSIS

Systematic searches of Medline, Embase, clinical trial registries, and other sources for all ongoing and completed randomised controlled trials comparing cord management strategies at preterm birth (before 37 weeks' gestation) have been completed up to 13 February 2019, but will be updated regularly to include additional trials. IPD will be sought for all trials; aggregate summary data will be included where IPD are unavailable. First, deferred clamping and cord milking will be compared with immediate clamping in pairwise IPD meta-analyses. The primary outcome will be death prior to hospital discharge. Effect differences will be explored for prespecified participant subgroups. Second, all identified cord management strategies will be compared and ranked in an IPD NMA for the primary outcome and the key secondary outcomes. Treatment effect differences by participant characteristics will be identified. Inconsistency and heterogeneity will be explored.

ETHICS AND DISSEMINATION

Ethics approval for this project has been granted by the University of Sydney Human Research Ethics Committee (2018/886). Results will be relevant to clinicians, guideline developers and policy-makers, and will be disseminated via publications, presentations and media releases.

REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ANZCTR) (ACTRN12619001305112) and International Prospective Register of Systematic Reviews (PROSPERO, CRD42019136640).

Dietary gluten reduces the number of intestinal regulatory T cells in mice

It is well established that gluten-free diet reduces the incidence of type 1 diabetes mellitus (T1D) in non-obese diabetic (NOD) mice, though the mechanism is not known. However, regulatory T cells (Treg) are likely to play an important role. Also, it is known that dietary gluten induces an intestinal increase in the bacterium Lactococcus garvieae, but the importance of this phenomenon for T1D development is doubtful. Our hypothesis is that gluten is responsible for mediating its effect on T1D through the influence on Treg development independent of gluten-induced Lactococci. Four groups of female NOD and BALB/c mice of 3 week old were fed either a gluten-free diet or a standard diet. Lactococcus garvieae or saline water was administered per oral to one of each dietary group. Spleen and Peyer's patches were sampled from BALB/c mice for flow cytometric monitoring of IL-10 and Treg. NOD mice were diagnosed diabetic with blood glucose level >12 mmol/l. Dietary gluten significantly decreased the occurrence of Tregs by 10-15% (P < 0.05) in mice compared with those fed a standard diet. These results and the diabetes incidence were independent of the gluten-induced bacterial factor Lactococci. The prevalence of Treg was 5- to 10-fold more abundant in the Peyer's patches than in the spleen (P < 0.001). In conclusion, dietary gluten has a significant negative quantitative impact on the generation of Treg in mice, independent of gluten-induced Lactococcus garvieae, and Treg are far more abundant in Peyer's patches than in the spleen.

Enhanced Surveillance of Infectious Diseases : the 2006 FIFA World Cup experience, Germany

The 2006 FIFA World Cup was held in 12 German cities between 9 June and 9 July 2006. We identified a need to accelerate and sensitise the pre-existing surveillance system for infectious diseases in order to timely detect adverse health events during the World Cup. Enhanced surveillance, based on Germany’s pre-existing system of mandatory notifications was conducted between 7 June and 11July 2006 in the 12 World Cup cities by: accelerating frequency of electronic data transmission of case-definition based notifiable diseases from weekly to daily transmission, additional reporting of non-case definition-based infectious disease events, lay and expert press screening and intensifying communication between all stakeholders of the surveillance system. Median delay of notification data transmission from the community to the federal level was reduced from three days to one day. The enhanced reporting system detected a norovirus outbreak in the International Broadcast Centre in Munich with 61 epidemiologically linked cases within the first week after onset, as well as four single cases related to the World Cup, two of them with relevance for the International Health Regulations. After the World Cup, all surveillance stakeholders agreed that communication between local, state and federal levels had improved considerably. Unlike the majority of health planners of previous mass gatherings in the last decade we did not introduce syndromic surveillance. Nevertheless, enhancement of infectious disease surveillance successfully detected adverse health events in a timely manner during the FIFA World Cup. Additionally, it provided a valuable communication and networking exercise for potentially critical health-related events. We recommend continuing daily notification data transmission for routine infectious disease surveillance in Germany.

Preparations for infectious disease surveillance during the football World Cup tournament, Germany 2006

Germany will be hosting the upcoming 2006 Football World Cup, scheduled to take place from June 9 to July 9. The games are expected to draw 3.2 million fans from within Germany, as well as many other countries.

Enhanced surveillance of infectious diseases : the 2006 FIFA World Cup experience, Germany

The 2006 FIFA World Cup was held in 12 German cities between 9 June and 9 July 2006. We identified a need to accelerate and sensitise the pre-existing surveillance system for infectious diseases in order to timely detect adverse health events during the World Cup. Enhanced surveillance, based on Germany's pre-existing system of mandatory notifications was conducted between 7 June and 11 July 2006 in the 12 World Cup cities by: accelerating frequency of electronic data transmission of case-definition based notifiable diseases from weekly to daily transmission, additional reporting of non-case definition-based infectious disease events, lay and expert press screening and intensifying communication between all stakeholders of the surveillance system. Median delay of notification data transmission from the community to the federal level was reduced from three days to one day. The enhanced reporting system detected a norovirus outbreak in the International Broadcast Centre in Munich with 61 epidemiologically linked cases within the first week after onset, as well as four single cases related to the World Cup, two of them with relevance for the International Health Regulations. After the World Cup, all surveillance stakeholders agreed that communication between local, state and federal levels had improved considerably. Unlike the majority of health planners of previous mass gatherings in the last decade we did not introduce syndromic surveillance. Nevertheless, enhancement of infectious disease surveillance successfully detected adverse health events in a timely manner during the FIFA World Cup. Additionally, it provided a valuable communication and networking exercise for potentially critical health-related events. We recommend continuing daily notification data transmission for routine infectious disease surveillance in Germany.

Detection of lactococcal 936-species bacteriophages in whey by magnetic capture hybridization PCR targeting a variable region of receptor-binding protein genes

AIMS

To develop PCR assays able to distinguish between groups within lactococcal 936-species bacteriophages, as defined by their different receptor-binding protein (RBP) genes.

METHODS AND RESULTS

DNA sequences of RBP genes from 17 lactococcal bacteriophages of the 936-species were compared, and six phage groups were identified. For each phage group a specific primer pair targeting a variable region of the RBP genes was designed. In nine of 20 whey samples, from dairies with recorded phage problems, between one and six phage groups were identified by conventional PCR. The sensitivity and specificity of the method was improved by magnetic capture hybridization (MCH)-PCR using a capture probe targeting an 80-bp highly conserved region just upstream from the RBP gene in all the investigated phages. The MCH-PCR was performed on 100 microl whey samples and the detection limit of the assay was 10(2)-10(3) PFU ml(-1) as opposed to the detection limit of 10(4) PFU ml(-1) for conventional PCR performed on 1-microl whey samples.

CONCLUSIONS

In this study, PCR assays have been developed to detect six different types of RBP genes in lactococcal 936-species bacteriophages.

SIGNIFICANCE AND IMPACT OF THE STUDY

The PCR assays have practical applications at cheese plants for detection of 936-species phages with different RBP and thereby potentially with different host ranges. This knowledge will make it possible to improve starter culture rotation systems in the dairy industry.

Characterization and purification of acidocin CH5, a bacteriocin produced by Lactobacillus acidophilus CH5

AIMS

To characterize and to purify a bacteriocin produced by Lactobacillus acidophilus strain with its activity restricted to Gram-positive bacteria.

METHODS AND RESULTS

Native acidocin CH5, a bacteriocin produced by L. acidophilus CH5 an isolate from a dairy starter culture forms in MRS (Oxoid, Basingstoke, UK) broth high-molecular weight aggregates which can dissociate into smaller units (retained by 5 kDa membrane) with higher activity. Acidocin CH5 was purified using combinations of chromatographic methods based on hydrophobic and cation exchange principles and the N-terminal region was sequenced.

CONCLUSIONS

Based on our results it is evident that acidocin CH5 belongs, according to bacteriocin classification, to the class II bacteriocins with identical N-terminal amino acid sequence described in the literature previously.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study has provided further data on bacteriocin acidocin CH5 from class II with wide spectrum of antimicrobial activity atypical for bacteriocins produced by L. acidophilus sharing the same homology.

Improvement of phage defence in Lactococcus lactis by introduction of the plasmid encoded restriction and modification system LlaAI

AIMS

To study the ability of the plasmid-encoded restriction and modification (R/M) system LlaAI to function as a bacteriophage resistance mechanism in Lactococcus lactis during milk fermentations.

METHODS AND RESULTS

Plasmid pAIcat4, carrying the R/M system LlaAI and a chloramphenicol resistance cassette, was introduced into the plasmid-free strain L. lactis MG1614 and the industrial strain L. lactis 964. By measuring changes in conductivity the influence of different phage on the growth was determined.

CONCLUSIONS

The plasmid-encoded R/M system LlaAI significantly improves the bacteriophage resistance of L. lactis during milk fermentations.

SIGNIFICANCE AND IMPACT OF THE STUDY

It is essential to determine the potential of a phage defence mechanism in L. lactis starter culture strains during growth in milk before steps are taken to improve starter cultures. This study shows that LlaAI is useful for improvement of starter cultures.

The ability of the plasmid-encoded restriction and modification system LlaBIII to protect Lactococcus lactis against bacteriophages

AIMS

To investigate the potential of the plasmid-encoded restriction and modification (R/M) system LlaBIII to protect Lactococcua lactis against bacteriophages during milk fermentations.

METHODS AND RESULTS

The R/M system LlaBIII on plasmid pJW566 was cloned with a chloramphenicol cassette, resulting in plasmid pJK1. When introduced into L. lactis strains, pJK1 conferred increased phage resistance against the three most common lactococcal phage species 936, c2, and P335 and three unclassified industrial phages. The growth of the strains in RSM was not affected by the presence of plasmid pJK1.

CONCLUSIONS

The plasmid-encoded R/M system LlaBIII has great ability to protect L. lactis strains against bacteriophages in milk fermentations.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study evaluates the ability of the LlaBIII R/M system to function as a phage defence mechanism which is an essential step prior to considering utilizing it for improving starter cultures.

The LlaGI restriction and modification system of Lactococcus lactis W10 consists of only one single polypeptide

The naturally occurring 12.1-kb plasmid, pEW104, in Lactococcus lactis ssp. cremoris W10 was found to confer decreased bacteriophage sensitivity to its host. Plasmid pEW104 encodes a non-classic restriction and modification (R/M) system, named LlaGI, consisting of only one single polypeptide. Analysis of the amino acid sequence revealed the presence of a catalytic motif and seven helicase-like motifs (DEAD-box motifs) characteristic of type I and III endonucleases, followed by four conserved methylase motifs characteristic of adenine-methylases. A comparison between LlaGI and the very similar R/M system, LlaBIII, suggests that the C-terminal region of LlaGI, apparently containing no known motifs, could possibly specify target DNA recognition. Conceivably, the LlaGI gene is included in the operon of the plasmid replication machinery. Finally, it is proposed that LlaGI represents a variant of the type I R/M systems.

Characterization of a novel plasmid-encoded HsdS subunit, S.LlaW12I, from Lactococcus lactis W12

A novel type I restriction-modification specificity subunit, S. LlaW12I, has been identified on the naturally occurring 8.0-kb plasmid pAW122 in the lactic acid bacterium Lactococcus lactis subsp. cremoris W12. Presence of the HsdS protein together with a complete type I restriction-modification system conferred increased phage restriction to the host, indicating exchange of specificity subunits. Sequence analysis showed that the S.LlaW12I subunit is most probably of type IC. Presumably, the hsdS gene is organized together with the repB gene on one transcriptional unit.

TPW22, a lactococcal temperate phage with a site-specific integrase closely related to Streptococcus thermophilus phage integrases

The temperate phage TPW22, induced from Lactococcus lactis subsp. cremoris W22, and the evolutionarily interesting integrase of this phage were characterized. Phage TPW22 was propagated lytically on L. lactis subsp. cremoris 3107, which could also be lysogenized by site-specific integration. The attachment site (attP), 5'-TAAGGCGACGGTCG-3', of phage TPW22 was present on a 7.5-kb EcoRI fragment, a 3.4-kb EcoRI-HindIII fragment of which was sequenced. Sequence information revealed the presence of an integrase gene (int). The deduced amino acid sequence showed 42 and 28% identity with integrases of streptococcal and lactococcal phages, respectively. The identities with these integrase-encoding genes were 52 and 45%, respectively, at the nucleotide level. This could indicate horizontal gene transfer. A stable integration vector containing attP and int was constructed, and integration in L. lactis subsp. cremoris MG1363 was obtained. The existence of an exchangeable lactococcal phage integration module was suggested. The proposed module covers the phage attachment site, the integrase gene, and surrounding factor-independent terminator structures. The phages phiLC3, TP901-1, and TPW22 all have different versions of this module. Phylogenetically, the TPW22 Int links the phiLC3 lactococcal integrase with known Streptococcus thermophilus integrases.

The antimicrobial activity of acidocin CH5 in MRS broth and milk with added NaCl, NaNO3 and lysozyme

The ability of acidocin CH5, a bacteriocin from Lactobacillus acidophilus CH5 in the form of neutralized and heated supernatant, to prevent the growth of the indicator Lactobacillus delbrueckii subsp. lactis LTI 30 alone or together with other antimicrobials was investigated. The inhibitory activity of acidocin CH5 was higher in MRS broth than in reconstituted skim milk (RSM). In MRS broth and RSM, 1.92 and 32 AU acidocin CH5/ml, respectively, caused 97 and 89% inhibition of the indicator Lactobacillus delbrueckii subsp. lactis LTI 30. The presence of 5 and 10% milk fat in RSM decreased the inhibitory activity of acidocin CH5 to 20 and 11%, respectively. The inhibitory activity of acidocin CH5 was also reduced in the presence of NaCl, NaNO3 and lysozyme. In RSM the inhibition was weaker with both acidocin CH5 and NaCl added compared with NaCl alone. In MRS broth the inhibition was stronger with both acidocin CH5 and NaCl added compared with NaCl alone. The inhibition of the indicator Lactobacillus delbrueckii subsp. lactis LTI 30 was stronger with both NaNO3 and acidocin CH5 in MRS broth (but not in RSM) than with only NaNO3 present, but the strongest level was obtained with acidocin CH5 alone. Addition of acidocin CH5 and more than 30 mg/ml lysozyme to MRS broth increased the level of inhibition above the level obtained by acidocin CH5 alone. The indicator Lactobacillus delbrueckii subsp. lactis LTI 30 was also sensitive to NaCl, NaNO3 and lysozyme in both MRS broth and RSM.

Cloning and characterization of the lactococcal plasmid-encoded type II restriction/modification system, LlaDII

The LlaDII restriction/modification (R/M) system was found on the naturally occurring 8.9-kb plasmid pHW393 in Lactococcus lactis subsp. cremoris W39. A 2.4-kb PstI-EcoRI fragment inserted into the Escherichia coli-L. lactis shuttle vector pCI3340 conferred to L. lactis LM2301 and L. lactis SMQ86 resistance against representatives of the three most common lactococcal phage species: 936, P335, and c2. The LlaDII endonuclease was partially purified and found to recognize and cleave the sequence 5'-GC decreases NGC-3', where the arrow indicates the cleavage site. It is thus an isoschizomer of the commercially available restriction endonuclease Fnu4HI. Sequencing of the 2.4-kb PstI-EcoRI fragment revealed two open reading frames arranged tandemly and separated by a 105-bp intergenic region. The endonuclease gene of 543 bp preceded the methylase gene of 954 bp. The deduced amino acid sequence of the LlaDII R/M system showed high homology to that of its only sequenced isoschizomer, Bsp6I from Bacillus sp. strain RFL6, with 41% identity between the endonucleases and 60% identity between the methylases. The genetic organizations of the LlaDII and Bsp6I R/M systems are identical. Both methylases have two recognition sites (5'-GCGGC-3' and 5'-GCCGC-3') forming a putative stemloop structure spanning part of the presumed -35 sequence and part of the intervening region between the -35 and -10 sequences. Alignment of the LlaDII and Bsp6I methylases with other m5C methylases showed that the protein primary structures possessed the same organization.

Determination of the recognition sequence of the type II restriction endonuclease, LlaCI, from Lactococcus lactis W15

A new type II restriction endonuclease, called LlaCI, was partially purified from Lactococcus lactis subsp. cremoris W15. The characterisation of the LlaCI endonuclease showed it to be an isoschizomer of HindIII, recognising the sequence 5-'A decreases AGCTT-3'. The cleavage site is indicated by the arrow.

Characterization of LlaCI, a new restriction-modification system from Lactococcus lactis subsp. cremoris W15

The genes encoding the restriction-modification (R/M) system LlaCI have been found on the naturally occurring 7.0 kb plasmid pAW153 in L. lactis subsp. cremoris W15. The R/M system was isolated on a chloramphenicol resistant derivative of the wild type plasmid (pAW153cat). Plasmid pAW153cat and a 2.4 kb HincII-SphI fragment cloned into a high- and a low-copy vector conferred decreased sensitivity in L. lactis LM2301 and L. lactis SMQ86 against small isometric-headed phages of the 936 or P335 species, respectively. Increased plasmid copy number enhanced the level of phage restriction. Sequencing the 2.4 kb HincII-SphI fragment revealed two open reading frames arranged convergently with a 94 bp separation. IlaCIM showed 66% identity to hindIIIM, and IlaCIR showed 45% identity to hindIIIR. The organization of the LlaCI operon differs from the HindIII operon, where the endonuclease and methylase genes overlap and are transcribed in the same direction. The LlaCI methylase is predicted to be 296 amino acids long, with 63% identity to the HindIII methylase, while the LlaCI endonuclease is predicted to consist of 324 or 332 amino acids, depending on the position of the start codon. It shows 24% identity to the HindIII endonuclease.

Replication regions of two pairs of incompatible lactococcal theta-replicating plasmids

Incompatibility tests were performed employing 12 replicons belonging to a family of homologous lactococcal theta-replicating plasmids. Two pairs of incompatible plasmids were found, namely, pFV1001 and pFV1201, and pJW565 and pFW094. The replicons of plasmids pFV1001, pFV1201, pJW565, pJW566, and pFW094 were sequenced. Alignments were made of the replicational origins (repA) and putative replication proteins (RepB) of these and 11 related plasmid sequences. Comparison of the alignments with the incompatibility data indicated that the incompatibility determinant could be contained within the 22-bp tandem repeats DRII and/or the inverted repeat IR1 in repA. In support, the incompatibility determinant of pJW563 was localized to a 743-bp fragment encompassing repA. A stretch of 13 amino acids of RepB was proposed to be responsible for the plasmid-specific initiation of replication. This stretch is part of a domain containing features that are highly conserved within the proposed DNA binding regions of the initiation proteins from several well-characterized plasmids from Gram-negative bacteria, including pSC101, R6K, and mini-F.

Cloning and analysis of the restriction-modification system LlaBI, a bacteriophage resistance system from Lactococcus lactis subsp. cremoris W56

The genes coding for the type II restriction-modification (R/M) system LlaBI, which recognized the sequence 5'-C decreases TRYAG-3', have been cloned from a plasmid in Lactococcus lactis subsp. cremoris W56 and sequenced. The DNA sequence predicts an endonuclease of 299 amino acids (33 kDa) and a methylase of 580 amino acids (65 kDa). A 4.0-kb HindIII fragment in pSA3 was able to restrict bacteriophages, showing that the cloned R/M system can function as a phage defense mechanism in L. lactis.

Characterization of the replicon from the lactococcal theta-replicating plasmid pJW563

The replication region of the lactococcal plasmid pJW563 was localized to a 2.3-kb EcoRI fragment. This DNA fragment was sequenced ans a 1155-bp open reading frame, repB563, encoding a putative protein RepB563 of 385 amino acids was found. An AT-rich noncoding region, repA563, was found upstream of repB563. This segment included several direct and inverted repeats. A downstream 591-bp open reading frame, ORF X, which was not necessary for replication, was putatively translationally coupled to repB563, RepB563 supplied in trans could support replication of a plasmid containing repA563 and a truncated repB563. This observation suggests that RepB563 is a trans-acting replication protein, and repA563 the cis-acting origin of replication, repA563, repB563, and the beginning of ORF X showed high homology to similar regions in a family of lactococcal theta-replicating plasmids. The repA DNA sequences and the RepB amino acid sequences of the plasmids were aligned and the consensus sequences generated. The comparison revealed highly conserved areas among this family of plasmids. In addition, variable domains emerged, presumably having a plasmid specific function, pVS40 and pC1305 were plasmids with replication proteins showing high homology to RepB563. Despite this homology, replication from repA563 could not be supported by the pVS40 or pC1305 replication protein supplied in trans. Likewise the pJW563 protein could not support replication from the pVS40 origin. pJW563 was found to be compatible with the pVS40 and pC1305 replicons. The results indicate that pJW563 belongs to the widespread family of lactococcal theta-replicating pladmids. Despite the high homology between their replicons, the interaction between the replication origin and the protein is highly specific in many cases rendering the plasmids compatible.

Restriction-modification systems in Lactococcus lactis

Several restriction-modification (R-M) systems have been identified in Lactococcus lactis. Most of the systems have been plasmid encoded and function as phage-resistance mechanisms. At least five different type-II R-M systems, LlaAI, LlaBI, LlaCI, LlaDI and LlaEI, were identified in isolates from a mixed Cheddar starter culture. LlaAI and LlaBI recognized the DNA sequences 5'- decreases GATC-3' and 5'-C decreases TRYAG-3', respectively. The genes coding for the LlaAI and LlaBI R-M systems have been cloned and sequenced. The LlaAI R-M system had two genes coding for methyltransferases (MTases) and one gene coding for a restriction endonuclease (ENase). The MTases showed high homology to the MTases from DpnII. The LlaBI R-M system had one gene coding for a MTase and one gene coding for an ENase.

LlaAI and LlaBI, two type-II restriction endonucleases from Lactococcus lactis subsp. cremoris W9 and W56 recognizing, respectively, 5'-/GATC-3' and 5'-C/TRYAG-3'

Two type-II restriction endonucleases have been purified from Lactococcus lactis subsp. cremoris W9 and W56, the strains isolated from a mixed Cheddar starter. Their characterization showed that LlaAI was an isoschizomer of MboI from Morexella bovis with the cleaving sequence, 5'/GATC-3', being sensitive to methylation of the adenine residue; LlaBI was an isoschizomer to SfcI from Streptococcus faceium with the cleaving sequence, 5'-C/TRYAG-3'. Both LlaAI and LlaBI restriction-modification (R-M) systems are encoded by the plasmids, respectively, pFW094 and pJW563, protecting the harboring strain against phage attack.

Antimicrobial activity of lactic acid bacteria isolated from sour doughs: purification and characterization of bavaricin A, a bacteriocin produced by Lactobacillus bavaricus MI401

Three hundred and thirty-five lactic acid bacteria were isolated from sour doughs and screened for antagonistic activity. Of these 145 showed activity against one or several of the indicator strains used in the screening. The antimicrobial activity of 18 isolates were due to a proteinaceous compound. These 18 isolates belonged to three different Lactobacillus species: Lactobacillus bavaricus, Lactobacillus curvatus and Lactobacillus plantarum. The spectrum of antimicrobial activity for the three species suggested that the inhibitory components were different. The inhibitory compound from Lact. bavaricus MI401 was chosen for further study. The proteinaceous nature, antimicrobial activity against closely-related species, heat resistance and sensitivity to alkaline treatment strongly indicated that this substance was a bacteriocin, which we designated bavaricin A. The bacteriocin was purified to homogeneity by ammonium sulphate precipitation, ion exchange, hydrophobic interaction and reverse-phase chromatography. The purification resulted in 193,000-fold increase in specific activity. SDS-PAGE of bavaricin A showed a molecular weight of 3500-4000 Da. By amino acid sequencing 41 amino acids were determined. Bavaricin A had a bactericidal mode of action and inhibited nine out of 10 Listeria monocytogenes. Lactobacillus bavaricus MI401 produced bavaricin A at temperatures from 4 degrees C to 30 degrees C. The production of active bavaracin A was inhibited at increasing sodium chloride concentration. In the presence of 3% sodium chloride at 4 degrees C no active bavaricin A could be detected. Nitrite (100 ppm) did not affect the production of active bavaricin A.

Stacking of three different restriction and modification systems in Lactococcus lactis by cotransformation

Four plasmids encoding restriction and modification (R/M) systems are described that are different in the specificity of their restrictive activity toward the small isometric phage p2 and prolate phage c2. The R/M plasmids were cotransformed into Lactococcus lactis MG1363 with pVS2, encoding resistance to chloramphenicol and erythromycin, to indicate successful transformation events. Analysis of cotransformants showed that three different R/M plasmids could be combined in L. lactis MG1363. The efficiency at which phage plaqued on the transformants decreased as the number of R/M plasmids increased. Some plasmid combinations were unstable suggesting replicon incompatibility.

CRP/cAMP- and CytR-regulated promoters in Escherichia coli K12: the cdd promoter

Transcriptional regulation of the deoP2 promoter by the cyclic AMP/cyclic AMP receptor protein complex (cAMP/CRP) and the CytR repressor requires two high-affinity CRP targets located around -41 and -93 bp preceding the start site for transcription. Here we report the structure of cddP, another CRP/CytR-regulated promoter. In common with what was found in deo, the cdd promoter also contains multiple CRP targets. Thus, using the DNasel footprinting procedure, tandem CRP binding sites were identified around -41 and -93. These findings support a general model for CytR binding and CytR regulation, in which (i) CytR and the CRP/cAMP complex bind to similar or identical targets, (ii) two or more targets are necessary for proper binding of CytR to a promoter region, and (iii) CytR represses transcription by antagonizing cAMP/CRP activation.

Phosphate buffer and salt medium concentrations affect the inactivation of T4 phage by platinum(II) complexes

The initial rate of inactivation of T4 phage by solutions of [Pt(NH3)2Cl2], [PtenCl2] and [Pten(H2O)2] (NO3)2 at fixed values of pH is strongly reduced by phosphate buffer, slightly reduced by acetate buffer and apparently not influenced by bis(2-hydroxyethyl)aminotris(hydroxymethyl)methane (BIS-Tris) buffer and HEPES buffer. The phosphate abolishes the antiphage activity of the platinum complexes probably by some sort of complex formation. This together with dimerization reactions qualitatively explains the tailing off of the phage inactivation rate. High concentrations of NaNO3 as the salt medium give increased phage inactivation rates, which are also strongly pH-dependent.

DNA Directed in Vitro Protein Synthesis with Escherichia coli S-30 Extracts

A DNA-directed cell-free protein synthesizing system was originally developed by Zubay (1). The system contains a crude extract prepared from Escherichia coli. This extract contains the machinery necessary for the transcription and translation, i.e., ribosomes and RNA polymerase. To this system, it is necessary to add all 20 amino acids, all four ribonucleotide triphosphates, transfer RNA, an energy generating system, and various salts. The DNA template is incubated with this mixture for at least 30 min at 37°C before gene products are examined. The following method is essentially as described by Zubay (1), but with minor modifications as described by Valentin-Hansen et al. (2).

Mapping of the gene for cytidine deaminase (cdd) in Escherichia coli K-12

The structural gene encoding cytidine deaminase (cdd) has been mapped in Escherichia coli K-12. It is located counterclockwise to ptsF between 46 and 47 min. The gene order in this region of the E. coli chromosome was found to be his-udk-gat-dld-cdd-ptsF.

Complement mediated lysis in chickens

Rat erythrocytes, when either injected i.v. into chickens, or incubated in vitro with chicken serum, will be lysed within minutes. This lysis is complement dependent but does not involve specific antibodies since Ig-free bursectomized chickens behave in exactly the same way as normal chickens with high levels of haemagglutinating antibodies. The lysis is mediated by activation of complement component C3 via the alternative complement pathway and various observations lead us to doubt the functional existence in this lytic reaction of the classical complement pathway.

Fusion of the lac genes to the promotor for the cytidine deaminase gene of Escherichia coli K-12

Phage Mu has been inserted into the structural gene for cytidine deaminase (cdd). By the use of phage lambda (lac, Mu) the promoter for the cdd gene has been fused to lacZ. In these strains lacZ expression is regulated by the cytR repressor protein and is therefore induced by cytidine. The fusion strains were used for the isolation of cddo mutants. Plaque forming lambda phages carrying the different cdd-lacZ fusions were isolated. Studies of the cdd-Mu strains showed that the cdd gene is transcribed clockwise with respect to the Escherichia coli map.

Platinum(II) complexes block the entry of T4 phage DNA into the host cells

The efficiency of multiplicity reactivation of T4 particles inactivated by platinum(II) complexes is very low. The same is true for marker rescue and functional survival of genes. This can be at least partly explained by the inability of most inactivated virus particles to introduce their DNA into the host cells as demonstrated by electron microscopy. Conformational changes in the DNA, formation of DNA-DNA and DNA-protein cross-links and the damage of proteins participating in the injection process could be responsible for the phenomenon observed.