Longitudinal natural history studies based on real-world data in rare diseases: Opportunity and a novel approach.

Growing interest in therapeutic development for rare diseases necessitate a systematic approach to the collection and curation of natural history data that can be applied consistently across this group of heterogenous rare diseases. In this study, we discuss the challenges facing natural history studies for leukodystrophies and detail a novel standardized approach to creating a longitudinal natural history study using existing medical records. Prospective studies are uniquely challenging for rare diseases. Delays in diagnosis and overall rarity limit the timely collection of natural history data. When feasible, prospective studies are often cross-sectional rather than longitudinal and are unlikely to capture pre- or early- symptomatic disease trajectories, limiting their utility in characterizing the full natural history of the disease. Therapeutic development in leukodystrophies is subject to these same obstacles. The Global Leukodystrophy Initiative Clinical Trials Network (GLIA-CTN) comprises of a network of research institutions across the United States, supported by a multi-center biorepository protocol, to map the longitudinal clinical course of disease across leukodystrophies. As part of GLIA-CTN, we developed Standard Operating Procedures (SOPs) that delineated all study processes related to staff training, source documentation, and data sharing. Additionally, the SOP detailed the standardized approach to data extraction including diagnosis, clinical presentation, and medical events, such as age at gastrostomy tube placement. The key variables for extraction were selected through face validity, and common electronic case report forms (eCRF) across leukodystrophies were created to collect analyzable data. To enhance the depth of the data, clinical notes are extracted into "original" and "imputed" encounters, with imputed encounter referring to a historic event (e.g., loss of ambulation 3 months prior). Retrospective Functional Assessments were assigned by child neurologists, using a blinded dual-rater approach and score discrepancies were adjudicated by a third rater. Upon completion of extraction, data source verification is performed. Data missingness was evaluated using statistics. The proposed methodology will enable us to leverage existing medical records to address the persistent gap in natural history data within this unique disease group, allow for assessment of clinical trajectory both pre- and post-formal diagnosis, and promote recruitment of larger cohorts.

Developmental delay can precede neurologic regression in early onset metachromatic leukodystrophy.

OBJECTIVE: Metachromatic leukodystrophy (MLD) is a rare neurodegenerative disorder. Emerging therapies are most effective in the presymptomatic phase, and thus defining this window is critical. We hypothesize that early development delay may precede developmental plateau. With the advent of presymptomatic screening platforms and transformative therapies, it is essential to define the onset of neurologic disease. METHODS: The specific ages of gain and loss of developmental milestones were captured from the medical records of individuals affected by MLD. Milestone acquisition was characterized as: on target (obtained before the age limit of 90th percentile plus 2 standard deviations compared to a normative dataset), delayed (obtained after 90th percentile plus 2 standard deviations), or plateau (skills never gained). Regression was defined as the age at which skills were lost. LI-MLD was defined by age at onset before 2.5 years. RESULTS: Across an international cohort, 351 subjects were included (n = 194 LI-MLD subcohort). The median age at presentation of the LI-MLD cohort was 1.4 years (25th-75th %ile: 1.0-1.5). Within the LI-MLD cohort, 75/194 (39%) had developmental delay (or plateau) prior to MLD clinical presentation. Among the LI-MLD cohort with a minimum of 1.5 years of follow-up (n = 187), 73 (39.0%) subjects never attained independent ambulation. Within LI-MLD + delay subcohort, the median time between first missed milestone target to MLD decline was 0.60 years (maximum distance from delay to onset: 1.9 years). INTERPRETATION: Early developmental delay precedes regression in a subset of children affected by LI-MLD, defining the onset of neurologic dysfunction earlier than previously appreciated. The use of realworld data prior to diagnosis revealed an early deviation from typical development. Close monitoring for early developmental delay in presymptomatic individuals may help in earlier diagnosis with important consequences for treatment decisions.

Biochemical signatures of disease severity in multiple sulfatase deficiency.

Sulfatases catalyze essential cellular reactions, including degradation of glycosaminoglycans (GAGs). All sulfatases are post-translationally activated by the formylglycine generating enzyme (FGE) which is deficient in multiple sulfatase deficiency (MSD), a neurodegenerative lysosomal storage disease. Historically, patients were presumed to be deficient of all sulfatase activities; however, a more nuanced relationship is emerging. Each sulfatase may differ in their degree of post-translational modification by FGE, which may influence the phenotypic spectrum of MSD. Here, we evaluate if residual sulfatase activity and accumulating GAG patterns distinguish cases from controls and stratify clinical severity groups in MSD. We quantify sulfatase activities and GAG accumulation using three complementary methods in MSD participants. Sulfatases differed greatly in their tolerance of reduction in FGE-mediated activation. Enzymes that degrade heparan sulfate (HS) demonstrated lower residual activities than those that act on other GAGs. Similarly, HS-derived urinary GAG subspecies preferentially accumulated, distinguished cases from controls, and correlated with disease severity. Accumulation patterns of specific sulfatase substrates in MSD provide fundamental insights into sulfatase regulation and will serve as much-needed biomakers for upcoming clinical trials. This work highlights that biomarker investigation of an ultra-rare disease can simultaneously inform our understanding of fundamental biology and advance clinical trial readiness efforts.

Variants in CLDN5 cause a syndrome characterized by seizures, microcephaly and brain calcifications.

The blood-brain barrier ensures CNS homeostasis and protection from injury. Claudin-5 (CLDN5), an important component of tight junctions, is critical for the integrity of the blood-brain barrier. We have identified de novo heterozygous missense variants in CLDN5 in 15 unrelated patients who presented with a shared constellation of features including developmental delay, seizures (primarily infantile onset focal epilepsy), microcephaly and a recognizable pattern of pontine atrophy and brain calcifications. All variants clustered in one subregion/domain of the CLDN5 gene and the recurrent variants demonstrate genotype-phenotype correlations. We modelled both patient variants and loss of function alleles in the zebrafish to show that the variants analogous to those in patients probably result in a novel aberrant function in CLDN5. In total, human patient and zebrafish data provide parallel evidence that pathogenic sequence variants in CLDN5 cause a novel neurodevelopmental disorder involving disruption of the blood-brain barrier and impaired neuronal function.

Self-Assembly of Ir-Based Nanosheets with Ordered Interlayer Space for Enhanced Electrocatalytic Water Oxidation.

Iridium (Ir)-based electrocatalysts are widely explored as benchmarks for acidic oxygen evolution reactions (OERs). However, further enhancing their catalytic activity remains challenging due to the difficulty in identifying active species and unfavorable architectures. In this work, we synthesized ultrathin Ir-IrOx/C nanosheets with ordered interlayer space for enhanced OER by a nanoconfined self-assembly strategy, employing block copolymer formed stable end-merged lamellar micelles. The interlayer distance of the prepared Ir-IrOx/C nanosheets was well controlled at ∼20 nm and Ir-IrOx nanoparticles (∼2 nm) were uniformly distributed within the nanosheets. Importantly, the fabricated Ir-IrOx/C electrocatalysts display one of the lowest overpotential (η) of 198 mV at 10 mA cm-2geo during OER in an acid medium, benefiting from their features of mixed-valence states, rich electrophilic oxygen species (O(II-δ)-), and favorable mesostructured architectures. Both experimental and computational results reveal that the mixed valence and O(II-δ)- moieties of the 2D mesoporous Ir-IrOx/C catalysts with a shortened Ir-O(II-δ)- bond (1.91 Å) is the key active species for the enhancement of OER by balancing the adsorption free energy of oxygen-containing intermediates. This strategy thus opens an avenue for designing high performance 2D ordered mesoporous electrocatalysts through a nanoconfined self-assembly strategy for water oxidation and beyond.

Otologic Disease Following Palatoplasty In International Cleft Palate Cohort.

OBJECTIVE: Study the prevalence of otologic disease in a pediatric post-palatoplasty population with no prior ear tube placement in resource-deprived countries and assess patient characteristics associated with these abnormal results. DESIGN: Retrospective data review. PARTICIPANTS: Ecuadorian and Chinese children identified during humanitarian cleft lip and palate repair trips with cleft palates undergoing palatoplasty from 2007 to 2010. INTERVENTIONS: Tympanometry and otoacoustic emission (OAE) testing performed following palatoplasty. Patients' parents administered surveys regarding perceived hearing deficits. MAIN OUTCOME MEASURES: Age, gender, Veau classification, follow-up time, laterality, and country of origin were evaluated for possible association with type B tympanogram, "Refer" Otoacoustic results, and presence of hearing difficulty as identified by a parent. Significant predictors were further evaluated with multivariate analysis. RESULTS: The cohorts included 237 patients (129 Ecuadorian, 108 Chinese); mean age: 3.9 years; mean follow-up: 4.2 years. Thirty-nine percent scored type B, 38% failed OAE testing, and 8% of parents noted hearing deficits. The country of origin and a younger age were identified as predictive variables regarding type B tympanogram. Follow-up time, country of origin, and bilateral OAE "Refer" results all significantly predicted parental questionnaire results. Subsequent multivariable analysis further demonstrated effect modification between the 2 variables of age at palatoplasty and country of origin when predicting type B vs type A tympanometry. CONCLUSION: Without otologic intervention, cleft palate children in resource-deprived settings suffer type B tympanometry and failed OAE results with similar to increased incidences to other studied cleft palate populations with otologic interventions available.

Palatal Fistula Risk after Primary Palatoplasty: A Retrospective Comparison of a Humanitarian Organization and Tertiary Hospitals.

BACKGROUND: Humanitarian surgical organizations provide palatoplasties for patients without access to surgical care. Few organizations have evaluated the outcomes of these trips. This study evaluates the palatal fistula rate in patients from two cohorts in rural China and one in the United States. METHODS: This study compared the odds of fistula formation among three cohorts whose palates were repaired between 2005 and 2009. One cohort included 97 Chinese patients operated on by teams from the United States and Canada under the auspices of Resurge International. They were compared to cohorts at Huaxi Stomatology Hospital and the University of California San Francisco (UCSF). Age, fistula presence, and Veau class were compared among cohorts using Chi-square tests. Logistic regression was used to analyze predictors of fistula formation. RESULTS: The fistula risk was 35.4% in patients treated by humanitarian teams, 12.8% at Huaxi University Hospital and 2.5% at UCSF ( P < 0.001). Age and Veau class were associated with fistula formation (Age P = 0.0015; Veau P < 0.001). ReSurge and Huaxi patients had 20.2 and 5.6 times the odds of developing a fistula, respectively, compared to UCSF patients ( P < 0.01, both). A multivariable model controlling for surgical group, age, and gender showed an association between Veau class and the odds of fistula formation. CONCLUSIONS: Chinese children undergoing palatoplasty by international teams had higher odds of palatal fistula than children treated by Chinese surgeons in established institutions and children treated in the United States. More research is required to identify factors affecting complication rates in low-resource environments.

Palatal fistula risk after primary palatoplasty: a retrospective comparison of humanitarian operations and tertiary hospitals.

BACKGROUND: Humanitarian surgical organisations provide cleft palate repair for patients without access to surgical care. Despite decades of experience, very little research has assessed the outcomes of these trips. This study investigates the fistula rate in patients from two cohorts in rural China and one in the USA. METHODS: This retrospective study compared the odds of fistula presentation among three cohorts whose palates were repaired between April, 2005, and November, 2009. The primary cohort included 97 Chinese patients operated on in China by surgeons from ReSurge International. A second Chinese cohort of 250 patients was operated on at Huaxi University Hospital by Chinese surgeons. The third cohort of 120 patients from the University of California San Francisco (UCSF) was included for comparison over the same time period; data was taken from medical records. Age, fistula presentation, and Veau Class were compared between the three cohorts with χ(2) tests. Logistic regression was used to analyse predictors of fistula presentation among the three cohorts. This study received institutional review board approval from the UCSF, the Harvard School of Public Health, and physicians at Huaxi University Hospital, and written consent was obtained from study participants in China. FINDINGS: The fistula risk was 35·4% in ReSurge patients, 12·8% for patients at Huaxi University Hospital, and 2·5% for patients at UCSF (p<0·001). At the time of surgery 15·5% of the ReSurge patients were younger than 2 years old, whereas 90·8% of the UCSF children and 41·6% of the Huaxi children were (p<0·001). In the ReSurge cohort, 20·6% of patients had a Veau class of I or II, wheras 40·8% and 58·9% of UCSF and Huaxi patients, respectively, were in class I or II (p<0·001). Age and Veau Class were associated with fistula formation in a univariate analysis. (Veau Class III or IV vs I or II, odds ratio [OR] 6·399 [95% CI 3·182-12·871]; age, OR 1·071 [95% CI 1·024-1·122]). A multivariate model controlling for the surgical group, age at palatoplasty, and sex showed an association between Veau Class and the odds of fistula presentation (Class III or IV vs I or II, OR 5·630 [95% CI 2·677-11·837). In this model, UCSF patients and Huaxi patients had 0·064 and 0·451 times the odds of developing a fistula, respectively, compared with ReSurge patients (p<0·001 both). INTERPRETATION: Chinese children undergoing palatoplasty on surgical missions have higher post-operative odds of palatal fistula than do children treated by local physicians. Children in low-resource settings have higher complication rates than do children in high-resource settings. Older age at palatoplasty and a Veau class III and IV are associated with post-palatoplasty fistula. Furthermore demographic, socioeconomic, and cultural differences could play a part in palatoplasty fistula outcomes between these three populations. More research is needed to determine the effects of post-operative care, the skill of the providers, and the technique used in the surgery that play a role on fistula outcomes after primary palatoplasty, particularly in low-resource environments. FUNDING: None.

SIGIRR, a negative regulator of TLR/IL-1R signalling promotes Microbiota dependent resistance to colonization by enteric bacterial pathogens.

Enteric bacterial pathogens such as enterohemorrhagic E. coli (EHEC) and Salmonella Typhimurium target the intestinal epithelial cells (IEC) lining the mammalian gastrointestinal tract. Despite expressing innate Toll-like receptors (TLRs), IEC are innately hypo-responsive to most bacterial products. This is thought to prevent maladaptive inflammatory responses against commensal bacteria, but it also limits antimicrobial responses by IEC to invading bacterial pathogens, potentially increasing host susceptibility to infection. One reason for the innate hypo-responsiveness of IEC is their expression of Single Ig IL-1 Related Receptor (SIGIRR), a negative regulator of interleukin (IL)-1 and TLR signaling. To address whether SIGIRR expression and the innate hypo-responsiveness of IEC impacts on enteric host defense, Sigirr deficient (-/-) mice were infected with the EHEC related pathogen Citrobacter rodentium. Sigirr -/- mice responded with accelerated IEC proliferation and strong pro-inflammatory and antimicrobial responses but surprisingly, Sigirr -/- mice proved dramatically more susceptible to infection than wildtype mice. Through haematopoietic transplantation studies, it was determined that SIGIRR expression by non-haematopoietic cells (putative IEC) regulated these responses. Moreover, the exaggerated responses were found to be primarily dependent on IL-1R signaling. Whilst exploring the basis for their susceptibility, Sigirr -/- mice were found to be unusually susceptible to intestinal Salmonella Typhimurium colonization, developing enterocolitis without the typical requirement for antibiotic based removal of competing commensal microbes. Strikingly, the exaggerated antimicrobial responses seen in Sigirr -/- mice were found to cause a rapid and dramatic loss of commensal microbes from the infected intestine. This depletion appears to reduce the ability of the microbiota to compete for space and nutrients (colonization resistance) with the invading pathogens, leaving the intestine highly susceptible to pathogen colonization. Thus, SIGIRR expression by IEC reflects a strategy that sacrifices maximal innate responsiveness by IEC in order to promote commensal microbe based colonization resistance against bacterial pathogens.

WITHDRAWN: Spinal manipulative therapy for low-back pain.

BACKGROUND: Low-back pain is a costly illness for which spinal manipulative therapy is commonly recommended. Previous systematic reviews and practice guidelines have reached discordant results on the effectiveness of this therapy for low-back pain. OBJECTIVES: To resolve the discrepancies related to the use of spinal manipulative therapy and to update previous estimates of effectiveness, by comparing spinal manipulative therapy with other therapies and then incorporating data from recent high-quality randomized, controlled trials (RCTs) into the analysis. SEARCH METHODS: The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and CINAHL were electronically searched from their respective beginning to January 2000, using the Back Group search strategy; references from previous systematic reviews were also screened. SELECTION CRITERIA: Randomized, controlled trials (RCT) that evaluated spinal manipulative therapy for patients with low-back pain, with at least one day of follow-up, and at least one clinically-relevant outcome measure. DATA COLLECTION AND ANALYSIS: Two authors, who served as the authors for all stages of the meta-analysis, independently extracted data from unmasked articles. Comparison treatments were classified into the following seven categories: sham, conventional general practitioner care, analgesics, physical therapy, exercises, back school, or a collection of therapies judged to be ineffective or even harmful (traction, corset, bed rest, home care, topical gel, no treatment, diathermy, and minimal massage). MAIN RESULTS: Thirty-nine RCTs were identified. Meta-regression models were developed for acute or chronic pain and short-term and long-term pain and function. For patients with acute low-back pain, spinal manipulative therapy was superior only to sham therapy (10-mm difference [95% CI, 2 to 17 mm] on a 100-mm visual analogue scale) or therapies judged to be ineffective or even harmful. Spinal manipulative therapy had no statistically or clinically significant advantage over general practitioner care, analgesics, physical therapy, exercises, or back school. Results for patients with chronic low-back pain were similar. Radiation of pain, study quality, profession of manipulator, and use of manipulation alone or in combination with other therapies did not affect these results. AUTHORS' CONCLUSIONS: There is no evidence that spinal manipulative therapy is superior to other standard treatments for patients with acute or chronic low-back pain.

Loss of dlx5a/dlx6a Locus Alters Non-Canonical Wnt Signaling and Meckel's Cartilage Morphology.

The dlx genes encode transcription factors that establish a proximal-distal polarity within neural crest cells to bestow a regional identity during craniofacial development. The expression regions of dlx paralogs are overlapping yet distinct within the zebrafish pharyngeal arches and may also be involved in progressive morphologic changes and organization of chondrocytes of the face. However, how each dlx paralog of dlx1a, dlx2a, dlx5a and dlx6a affects craniofacial development is still largely unknown. We report here that the average lengths of the Meckel's, palatoquadrate and ceratohyal cartilages in different dlx mutants were altered. Mutants for dlx5a-/- and dlx5i6-/-, where the entire dlx5a/dlx6a locus was deleted, have the shortest lengths for all three structures at 5 days post fertilization (dpf). This phenotype was also observed in 14 dpf larvae. Loss of dlx5i6 also resulted in increased proliferation of neural crest cells and expression of chondrogenic markers. Additionally, altered expression and function of non-canonical Wnt signaling were observed in these mutants suggesting a novel interaction between dlx5i6 locus and non-canonical Wnt pathway regulating ventral cartilage morphogenesis.

Effect of Extremely Preterm Birth on Adolescent Brain Network Organization.

Introduction: Extremely preterm (EPT) birth, defined as birth at a gestational age (GA) <28 weeks, can have a lasting impact on cognition throughout the life span. Previous investigations reveal differences in brain structure and connectivity between infants born preterm and full-term (FT), but how does preterm birth impact the adolescent connectome? Methods: In this study, we investigate how EPT birth can alter broadscale network organization later in life by comparing resting-state functional magnetic resonance imaging connectome-based parcellations of the entire cortex in adolescents born EPT (N = 22) to age-matched adolescents born FT (GA ≥37 weeks, N = 28). We compare these parcellations to adult parcellations from previous studies and explore the relationship between an individual's network organization and behavior. Results: Primary (occipital and sensorimotor) and frontoparietal networks were observed in both groups. However, there existed notable differences in the limbic and insular networks. Surprisingly, the connectivity profile of the limbic network of EPT adolescents was more adultlike than the same network in FT adolescents. Finally, we found a relationship between adolescents' overall cognition score and their limbic network maturity. Discussion: Overall, preterm birth may contribute to the atypical development of broadscale network organization in adolescence and may partially explain the observed cognitive deficits.

Striatal µ-opioid receptor activation triggers direct-pathway GABAergic plasticity and induces negative affect.

Withdrawal from chronic opioid use often causes hypodopaminergic states and negative affect, which may drive relapse. Direct-pathway medium spiny neurons (dMSNs) in the striatal patch compartment contain µ-opioid receptors (MORs). It remains unclear how chronic opioid exposure and withdrawal impact these MOR-expressing dMSNs and their outputs. Here, we report that MOR activation acutely suppressed GABAergic striatopallidal transmission in habenula-projecting globus pallidus neurons. Notably, withdrawal from repeated morphine or fentanyl administration potentiated this GABAergic transmission. Furthermore, intravenous fentanyl self-administration enhanced GABAergic striatonigral transmission and reduced midbrain dopaminergic activity. Fentanyl-activated striatal neurons mediated contextual memory retrieval required for conditioned place preference tests. Importantly, chemogenetic inhibition of striatal MOR+ neurons rescued fentanyl withdrawal-induced physical symptoms and anxiety-like behaviors. These data suggest that chronic opioid use triggers GABAergic striatopallidal and striatonigral plasticity to induce a hypodopaminergic state, which may promote negative emotions and relapse.

Subgroup-specific alternative splicing in medulloblastoma.

Medulloblastoma comprises four distinct molecular variants: WNT, SHH, Group 3, and Group 4. We analyzed alternative splicing usage in 14 normal cerebellar samples and 103 medulloblastomas of known subgroup. Medulloblastoma samples have a statistically significant increase in alternative splicing as compared to normal fetal cerebella (2.3-times; P < 6.47E-8). Splicing patterns are distinct and specific between molecular subgroups. Unsupervised hierarchical clustering of alternative splicing events accurately assigns medulloblastomas to their correct subgroup. Subgroup-specific splicing and alternative promoter usage was most prevalent in Group 3 (19.4%) and SHH (16.2%) medulloblastomas, while observed less frequently in WNT (3.2%), and Group 4 (9.3%) tumors. Functional annotation of alternatively spliced genes reveals overrepresentation of genes important for neuronal development. Alternative splicing events in medulloblastoma may be regulated in part by the correlative expression of antisense transcripts, suggesting a possible mechanism affecting subgroup-specific alternative splicing. Our results identify additional candidate markers for medulloblastoma subgroup affiliation, further support the existence of distinct subgroups of the disease, and demonstrate an additional level of transcriptional heterogeneity between medulloblastoma subgroups.

Novel cross-regulation interactions between dlx genes in larval zebrafish.

The homeodomain-containing transcription factors dlx1a, dlx2a, dlx5a and dlx6a are expressed in the zebrafish brain in overlapping patterns and are important in vertebrate development. Previous work in mice have suggested the overlapping expression pattern is in part due to cross-regulatory interactions among the aforementioned dlx genes. However, the extent of these interactions and whether they are conserved among vertebrates remains to be determined. Through whole-mount in situ hybridization in zebrafish dlx mutants produced by CRISPR-Cas9 mutagenesis, cross-regulatory interactions between dlx1a, dlx2a, dlx5a and dlx6a were examined from 24 to 72 h post fertilization (hpf). Notably, and different from previous work done in mouse, zebrafish dlx2a-/- mutants continue to express dlx5a until 72hpf, whereas deletion of both enhancers within the dlx5a/dlx6a locus resulted in delayed dlx5a/dlx6a expression and relative increased dlx2a expression. These results suggest alternative regulatory elements and pathways exist to mediate dlx expression in zebrafish and may highlight evolutionary differences in gene interactions between vertebrates.

Tailoring Surface Self-Organization for Nanoscale Polygonal Morphology on Germanium.

The evolution of polygonal-shaped nanoholes on the (100) surface of germanium, aided by focused ion beam induced self-organization, is presented. The energetic beam of ions creates a viscous phase which, at a thermodynamical minimum, leads to surface self-organization. A directed viscous-flow along the predefined nanoholes provides well-ordered polygonal nanostructures, ranging from triangles to hexagons and octagons, as desired. The amorphization exhibiting a confined viscous-flow at the walls of nanoholes is attributed to the localized melting zones induced by site-specific thermal spikes during ion irradiation, as revealed by microscopy and molecular dynamics studies. This leads to a local self-organization in the vicinity of each circular nanohole via a viscous-fingering process at the nanoscale. Such controlled self-organization, with the help of a predefined scanning grid, transforms the circular holes into the desired polygonal shape. The present morphology manipulation promises to surmount the barriers concerning the size reduction efforts in the field of nanofabrication.

Occupational Exposure in Health Care Personnel to Antineoplastic Drugs and Initiation of Safe Handling in Hong Kong: A Literature Review.

Despite the benefits for patients as cancer treatment, antineoplastic drugs may cause adverse effects not only in patients but also in health care personnel. Apart from minor symptoms, antineoplastic agents can cause serious health problems. However, protection from occupational exposures to antineoplastic drugs varies between pharmacy staff and nurses. While protection used for pharmacy staff are more advanced, personal protective equipment seems to be the only protection for most nurses around the world. Exposure can never be totally prevented, but it should be minimized at all costs. Guidelines and recommendations have been published; however, these guidelines do not have legal enforcement power. This article aims to provide a literature review on the occupational exposure of health care personnel to antineoplastic drugs and to reflect the current status in Hong Kong.

Characterization of the Competitive Pneumocin Peptides of Streptococcus pneumoniae.

In the polymicrobial environment of the human nasopharynx, Streptococcus pneumoniae (pneumococcus) competes with other members of the microbial community for limited nutrients in part by secreting small peptide bacteriocins called pneumocins. Pneumocin production is controlled by a quorum sensing system encoded by the blp locus. Although the locus is found in all pneumococci, there is significant variability in the repertoire of pneumocins and associated immunity proteins encoded in the Bacteriocin Immunity Region (BIR) and in the presence or absence of a functional Blp transporter. Strains without an active Blp transporter are inactive in plate overlay assays and rely on a homologous transporter that is only produced during brief periods of competence to stimulate the blp locus and secrete pneumocins. The variability of the locus suggests that selective pressure is influencing the content to promote the optimal competitive environment. Much of the variability in the blp locus has been described at the genome level; the phenotypic activity attributable to the various BIR genes has not been fully described. To examine the role of the predicted pneumocin peptides in competition, 454 isolates were screened for competence independent blp pheromone secretion using plate assays. Active strains were characterized for inhibition, BIR content, BlpC pherotype and serotype. Deletion analysis on inhibitory strains demonstrated that BlpI and BlpJ peptides function as a two-peptide bacteriocin and that BlpIJ immunity is encoded by the co-transcribed blpU4/5 genes. BlpIJ secretion promotes inhibitory activity against the majority of pneumococcal isolates when expressed in a Blp transporter intact background. Intermediate levels of competition in biofilms were noted when BlpIJ containing strains carried the non-functional Blp transporter. Based on genome data, the combination of BlpIJ in a Blp transporter intact strain is surprisingly rare, despite clear advantages during colonization and biofilm growth. In contrast, we show that the blpK/pncF operon encoding the single-peptide pneumocin BlpK and its immunity protein is found in the majority of isolates. Unlike, BlpIJ and BlpK were shown to promote a limited spectrum of inhibition due in part to immunity that is independent of activation of the blp locus.