Intravenous antibiotics in preterm infants have a negative effect upon microbiome development throughout preterm life

BACKGROUND

Intestinal dysbiosis is implicated in the origins of necrotising enterocolitis and late-onset sepsis in preterm babies. However, the effect of modulators of bacterial growth (e.g. antibiotics) upon the developing microbiome is not well-characterised. In this prospectively-recruited, retrospectively-classified, case-control study, high-throughput 16S rRNA gene sequencing was combined with contemporaneous clinical data collection, to assess the within-subject relationship between antibiotic administration and microbiome development, in comparison to preterm infants with minimal antibiotic exposure.

RESULTS

During courses of antibiotics, diversity progression fell in comparison to that seen outside periods of antibiotic use (-0.71units/week vs. + 0.63units/week, p < 0.01); Enterobacteriaceae relative abundance progression conversely rose (+ 10.6%/week vs. -8.9%/week, p < 0.01). After antibiotic cessation, diversity progression remained suppressed (+ 0.2units/week, p = 0.02).

CONCLUSIONS

Antibiotic use has an acute and longer-lasting impact on the developing preterm intestinal microbiome. This has clinical implications with regard to the contribution of antibiotic use to evolving dysbiosis, and affects the interpretation of existing microbiome studies where this effect modulator is rarely accounted for.

Perinatal inflammation influences but does not arrest rapid immune development in preterm babies

Infection and infection-related complications are important causes of death and morbidity following preterm birth. Despite this risk, there is limited understanding of the development of the immune system in those born prematurely, and of how this development is influenced by perinatal factors. Here we prospectively and longitudinally follow a cohort of babies born before 32 weeks of gestation. We demonstrate that preterm babies, including those born extremely prematurely (<28 weeks), are capable of rapidly acquiring some adult levels of immune functionality, in which immune maturation occurs independently of the developing heterogeneous microbiome. By contrast, we observe a reduced percentage of CXCL8-producing T cells, but comparable levels of TNF-producing T cells, from babies exposed to in utero or postnatal infection, which precedes an unstable post-natal clinical course. These data show that rapid immune development is possible in preterm babies, but distinct identifiable differences in functionality may predict subsequent infection mediated outcomes.

Diversity and stability of cultured vaginal lactobacilli in pregnant women from a multi-ethnic urban UK population

AIM

To determine the diversity and stability of cultured vaginal lactobacilli in a multi-ethnic population of pregnant women.

METHODS AND RESULTS

A single-centre, prospective, cohort study was performed in a tertiary perinatal centre in East London, UK. Self-collected vaginal swabs at 13 and 20 weeks gestation were obtained from women attending for routine antenatal care and cultured for lactobacilli. In women who provided both swabs, 37 of 203 (18%) had no lactobacilli cultured at either time. Only 53 (26%) had the same species at both times. Black women were less likely to have lactobacilli cultured at 13 weeks (P = 0·014), and Black and Asian women were less likely to have lactobacilli cultured at 20 weeks (P = 0·002) compared with those in the White and Other groups.

CONCLUSIONS

Significant differences exist between ethnic groups in the carriage and stability of vaginal lactobacilli.

SIGNIFICANCE AND IMPACT OF THE STUDY

These differences have implications for the design of interventions aimed at normalizing the vaginal microbiota in pregnant women.

Comparison of random amplified polymorphic DNA with restriction fragment length polymorphism as epidemiological typing methods for Mycobacterium tuberculosis

Aim-To compare restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) methods for the epidemiological typing of Mycobacterium tuberculosis.Methods-Thirty one M tuberculosis cultures originating from patients in the Canton of Berne in Switzerland, which had previously been typed by RFLP, were subjected to RAPD analysis. Cultures were coded so that the investigators were blind to the RFLP results until RAPD analysis was complete.Results-The 31 cultures of M tuberculosis were divided into nine groups by RFLP and eight groups by RAPD. Generally there was good correlation between the groups identified by the two techniques, with the exception of strains that had only one copy of IS6110. Both methods subdivided isolates that were placed in a single group by the other method.Conclusions-RAPD analysis is quick, simple, and useful for the comparison of small numbers of isolates. RFLP is more reproducible and therefore better suited for the accumulation of RFLP fingerprints for long term local surveillance and large epidemiological studies.

Molecular diagnosis of vascular access device-associated infection in children being treated for cancer or leukaemia

Blood samples were collected for quantitative 16S rDNA analysis from the vascular access device (VAD) of patients presenting with fever at participating centres of the UK Children's Cancer and Leukaemia Group. In total, 260 of 301 episodes of fever were evaluable and were classified as probable, possible, unlikely or unclassifiable VAD-associated infection. The sensitivity of the 16S rDNA assay declined concomitantly with delays from time of presentation to sampling. The sensitivity with >0.125 pg of bacterial DNA/microL of whole blood was 80% for the 20 probable VAD-associated infections diagnosed with samples collected on the day of or day following presentation. The specificity rose with increasing amounts of bacterial DNA, from 93% with >0.125 pg, to 98% with 0.25-0.5 pg, and to 100% with >0.5 pg/microL blood. The positive predictive value (for probable or possible) was 88% (95% CI 70-98%) with 0.25 pg/microL, and 100% (95% CI 83-100%) with >0.5 pg/microL. All 18 (6.8%) episodes with >0.5 pg of bacterial DNA/microL blood were associated with positive blood cultures. Identifications derived from the DNA sequence were consistent with the blood culture identifications for 15 of the 17 episodes with a DNA sequence identification. The VAD was removed because of suspected infection in six (2.8%) of 216 episodes with <0.125 pg of bacterial DNA/microL, in one (5%) of 20 episodes with 0.125-0.25 pg/microL, in one (16.7%) of six episodes with 0.25-0.5 pg/microL, and in nine (50%) of 18 episodes with >0.5 pg/microL. A bacterial DNA concentration of >0.5 pg/microL in blood drawn through a central venous catheter at the time of fever presentation had a high positive predictive value for VAD-associated infection and predicted an increased risk of VAD removal because of suspected infection.

Use of Once-Daily Netilmicin to Treat Infants with Suspected Sepsis in a Neonatal Intensive Care Unit

Once-daily administration of aminoglycoside antibiotics has become the most acceptable dosing schedule for the majority of patients. There are few published data on the impact of post-natal age on aminoglycoside concentrations in preterm infants receiving once-daily dosage regimens. Netilmicin was administered as a once-daily dose of 4 mg/kg. In 141 episodes of suspected sepsis in 123 babies, trough netilmicin concentrations ranged from undetectable to 4.0 mg/l. Netilmicin concentrations were above a level of 2 mg/l in 10.6% of episodes. Netilmicin concentrations decreased with increasing post-natal age and weight. Levels were higher in males compared to females. Increased creatinine concentrations were associated with higher netilmicin concentrations. This study emphasises the importance of post-natal age as a determinant of aminoglycoside concentrations with a once-daily dosing regimen in a neonatal intensive care population. Trough levels should be carefully monitored and consideration given to extending dosage intervals particularly when netilmicin is administered once daily to preterm infants in the first week of life.

Use of quantitative 16S ribosomal DNA detection for diagnosis of central vascular catheter-associated bacterial infection

Many central vascular catheters (CVCs) are removed unnecessarily because current diagnostic methods for CVC-associated infection are unreliable. A quantitative PCR assay using primers and probe targeted to bacterial 16S ribosomal DNA was used to measure the levels of bacterial DNA in blood samples drawn through the CVC in a population of patients receiving intravenous nutrition. Bacterial DNA concentrations were raised in 16 of 16 blood samples taken during episodes of probable bacterial CVC-associated infection. Bacterial DNA concentrations were raised in 4 of 29 episodes in which bacterial CVC-associated infection was unlikely. The use of this technique has the potential to substantially reduce the unnecessary removal of CVCs.

A novel polymerase chain reaction assay to detect Mycoplasma genitalium

AIMS

To design and validate a polymerase chain reaction (PCR) assay targeting the 16S rRNA gene of Mycoplasma genitalium.

METHODS

Primers were designed that were complementary to the 16S rRNA gene sequence of M genitalium. After optimisation of the reaction conditions, the PCR was tested against nine M genitalium strains, a dilution series of M genitalium DNA, and a panel of common microorganisms. The PCR was also challenged in parallel with a published assay against 54 urine specimens from men with urethritis.

RESULTS

The expected 341 bp product was produced on amplification of material from all M genitalium strains and from none of the other microorganisms tested. The lower limit of detection was 50 genome copies. The new assay detected M genitalium DNA in nine of 54 men with urethritis, in comparison with eight positive specimens detected with the alternative PCR.

CONCLUSIONS

This novel PCR targeting the M genitalium 16S rRNA gene has been optimised and now provides a sensitive and specific alternative or addition to the available MgPa gene targeting assays.

Application of a novel human cervical mucin-based assay demonstrates the absence of increased mucinase activity in bacterial vaginosis

Enzymes produced in bacterial vaginosis (BV) have been proposed as possible mediators of pre-term birth. Most studies have concentrated on mid-trimester measurements of enzyme activity, and utilize synthetic substrates to measure enzyme activity, which may not accurately represent mucinase activity in vivo. We have developed a novel ELISA mucinase assay using biotinylated human cervical mucin as a substrate. The assay is rapid, sensitive and can be used to screen large numbers of samples. The new assay has been used to assess vaginal mucinase activities in 92 women <14 weeks gestational age with and without BV. No differences in mucinase activity were detected between normal and BV groups while significant elevation of sialidase and other glycosidases was confirmed as reported before. This study shows that significant mucinase activity is a normal event in the mucus barrier, but does not reflect changes identified for individual enzyme activities associated with BV.

Expression of oestrogen receptor beta (ERbeta1) protein in human breast cancer biopsies

Oestrogen action is mediated via specific receptors that act as ligand-activated transcription factors. A monoclonal antibody specific to the C-terminus of human oestrogen receptor beta has been characterized and the prevalence of expression of oestrogen receptor beta protein investigated in a well defined set of breast cancers. Reverse transcription-polymerase chain reaction analysis of RNA from tissue biopsies detected oestrogen receptor beta in all samples examined. The anti-oestrogen receptor beta antibody cross reacted specifically with both long (approximately 59 Kd) and short (approximately 53 Kd) forms of recombinant oestrogen receptor beta. Western blot analysis of breast tumours contained both forms of oestrogen receptor beta protein although in some samples lower molecular weight species (32--45 Kd) were identified. Fifty-one breast cancer biopsies were examined using immunohistochemistry; 41 (80%) were immunopositive for oestrogen receptor alpha, 48 (94%) were immunopositive for oestrogen receptor beta and 38 (74.5%) co-expressed both receptors. Expression of oestrogen receptor beta was exclusively nuclear and occurred in multiple cell types. There was no quantitative relationship between staining for the two ERs although in tumours in which both receptors were present immunoexpression of oestrogen receptor alpha was invariably more intense. The significance of oestrogen receptor beta protein expression in breast cancers to therapy remains to be determined but the availability of a well characterized antibody capable of detecting oestrogen receptor beta in archive material will facilitate the process.

Development and validation of a new monoclonal antibody to mammalian aromatase

The biosynthesis of oestrogens from androgens is catalysed by the aromatase complex, an essential component of which is the aromatase cytochrome P450 (P450 arom) protein. Expression of a functional P450 arom is essential for normal fertility in males and females and the sequence of the protein is highly conserved. We have raised a new monoclonal antibody against a conserved peptide and validated it on fixed tissue sections of the rat, common marmoset (Callthrix jacchus) and human. The monoclonal antibody was used successfully for Western analysis and specifically reacted with a 55 kDa protein in microsomal extracts. On sections of ovaries in all three species, expression in follicles was specific to the mural granulosa cells of antral follicles and was present in corpora lutea. In the human and marmoset, staining of luteal cells was markedly heterogeneous and did not appear to vary consistently with the stage of the cycle. The intensity of immunostaining was elevated in corpora lutea from pregnant rats and following human chorionic gonadotropin rescue in the human. In the testis, the highest levels of expression were observed in the Leydig cells within the interstitium. In adult rat and marmoset, and possibly also in the human, some P450 arom was associated with the cytoplasm surrounding elongate spermatids but other germ cells were immunonegative. In conclusion, a new monoclonal antibody specific for P450 arom recognises the protein in rodent, primate and human. Its ability to work on fixed tissue sections will facilitate identification of individual cells expressing P450 arom within complex tissues.

Mucinases and sialidases: their role in the pathogenesis of sexually transmitted infections in the female genital tract

BACKGROUND

Mucinases and sialidases contribute to the process of invasion and colonisation in many conditions and infections of the female reproductive tract by degrading the protective cervical mucus. The role of hydrolytic enzymes in the pathogenesis of sexually transmitted diseases and their effect on cervical mucus are discussed in this review.

METHODS

Articles were searched for using the keywords "sialidase," "mucinase," "protease," and "sexually transmitted infections." As well as review and other articles held by our group, searches were conducted using PubMed, Grateful Med, and the University of Bath search engine, BIDS.

RESULTS

Numerous publications were found describing the production of hydrolytic enzymes in sexually transmitted diseases. Because the number of publications exceeded the restrictions imposed on the size of the review, the authors selected and discussed those which they considered of the most relevance to sexually transmitted infections.

Modulation of gene expression by androgen and oestrogens in the testis and prostate of the adult rat following androgen withdrawal

Androgens are important for the structural and functional integrity of the testis and the prostate and this may in part be mediated by the aromatisation of testosterone to oestradiol. The aim of the present study was to establish an in vivo model that would allow the identification of genes, the expression of which was regulated acutely by androgen and/or oestrogen in the male reproductive system. In rats in which the Leydig cells were ablated by administration of ethane dimethane sulfonate (EDS) 6 days earlier, testosterone esters (T) were administered from day 0 (To), and additional animals were administered either T, 17beta-oestradiol benzoate (EB) or diethylstilbestrol (DES) for 1 or 4 h on day 6 after EDS-treatment. Nuclear immunoexpression of the androgen receptor (AR) was reduced or absent from the testis but unaffected in the ventral prostate following these treatments. ERbeta immunoexpression in these tissues was unchanged. Northern blot analysis showed that EB and DES as well as T administration 4 h earlier could modulate mRNA expression of two androgen-responsive genes, C3 and SGP-2, in the prostate. The co-administration of T or EB with the AR antagonist, flutamide, or with the ER antagonist, ICI 182,780 (ICI), did not block the suppression of SGP-2 mRNA expression by T or EB. In contrast, the upregulation of C3 mRNA expression by T was successfully antagonised by both flutamide and by ICI. A preliminary evaluation of the expression of three Sertoli cell and five germ cell mRNAs revealed that their expression was not steroid regulated. Our results support the hypothesis that the action of testosterone in the male reproductive system may in part be mediated by its conversion to oestradiol. This in vivo model should prove of value in future studies to identify androgen and oestrogen regulated genes in the male reproductive system.

Carriage of antibiotic-resistant bacteria by healthy children

The frequency of carriage of antibiotic-resistant bacteria in healthy 7- and 8-year-old children in Bristol was studied. Children born in Avon between 1 April 1991 and 31 December 1992, attending the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC) 7 year follow-up clinic, formed the study population. Carriage was estimated using mouth and stool samples. None of 105 children on whom information was available had received tetracycline, chloramphenicol, ciprofloxacin or an extended-spectrum cephalosporin in the previous year. Staphylococcus aureus was isolated from mouthwashes from 200 (37.1%) of 539 children sampled. Six (3%) of the isolates were resistant to chloramphenicol or tetracycline and four (2%) were methicillin resistant. Haemophilus spp. were isolated from 369 (72%) of 513 samples and 63 (17%) were ampicillin resistant, 49 (13.3%) were erythromycin resistant and seven (1.9%) were tetracycline resistant. Branhamella catarrhalis was isolated from 333 (74%) of 450 samples. Twenty-eight (8.4%) were erythromycin resistant and 14 (4.2%) strains were tetracycline resistant. Group A beta-haemolytic streptococci were isolated from 17 of 507 children sampled. One (5.9%) was tetracycline resistant. Stool samples were returned from 335 (62%) of 539 children from whom they were requested. Eleven per cent of samples yielded Gram-negative bacilli with high-level resistance to chloramphenicol, which was frequently linked to resistance to ampicillin, spectinomycin and streptomycin. Isolates demonstrating resistance to the third-generation cephalosporin ceftazidime were recovered from 17 subjects (3.2%). Six (35%) of 17 isolates possessed extended-spectrum beta-lactamases. Healthy children carry bacteria resistant to antibiotics to which children are not usually exposed. Resistance to ceftazidime, chloramphenicol and tetracycline may be co-selected by exposure to other antibiotics used in children or may be acquired from family members, pets, other children or food. These results suggest that antibiotic-resistant bacteria are widely disseminated and may be acquired by children before exposure to specific selection pressure.

Estrogen receptor beta, but not estrogen receptor alpha, is present in the vascular endothelium of the human and nonhuman primate endometrium

Estrogen action is dependent upon the presence of specific ligand-activated receptors in target tissues. The aim of the present experiments was to compare the spatial and temporal pattern of expression of estrogen receptor beta (ERbeta) with that of ERalpha in full thickness endometrial samples (from the superficial to the basal zone) obtained from both women and rhesus macaques. Immunohistochemical localization with specific antibodies revealed that ERalpha and ERbeta were both expressed in nuclei of the glands and stroma. Consistent with previous studies, expression of ERalpha declined in the glands and stroma of the functionalis during the secretory phase. The luminal epithelium also displayed positive immunoreactivity for ERbeta. Expression of ERbeta declined in glandular cell nuclei, but not stroma, within the functionalis during the late secretory phase. Levels of expression of ERalpha and ERbeta in all cellular compartments remained unchanged in the basalis. Both receptor subtypes were detected on Western blots using proteins extracted from uterine samples obtained throughout the menstrual cycle. There was a striking contrast between the pattern of expression of ERalpha and ERbeta in the vascular endothelium and the perivascular cells surrounding endometrial blood vessels; only ERbeta was present in the endothelial cell population, although both forms of ER were expressed in perivascular cells. We conclude that estrogen action(s) within the vascular endothelium in the endometrium may be mediated via direct binding to the ERbeta isoform and that these cells could therefore be a target for agonists or antagonists that selectively target the beta form of the ER.

Differential expression of oestrogen receptor alpha and beta proteins in the testes and male reproductive system of human and non-human primates

The role(s) oestrogens play in male adult reproductive function remains uncertain. We have used antibodies specific for oestrogen receptor- alpha (ERalpha) and - beta (ERbeta) to investigate their distribution within the male. In testes from adult human, macaque and marmoset, ERbeta protein was detected in Sertoli cells, Leydig cells and peritubular myoid cells. In germ cells, the intensity of immunostaining for ERbeta was variable between species. Immunoexpression in preleptotene, leptotene and zygotene spermatocytes was low/absent in all species. Elongated spermatids were consistently immunonegative. No ERalpha immunoexpression was detected in testes. ERbeta was detected in epithelial and stromal cell nuclei throughout the male reproductive system [efferent ductules (ED), epididymis, vas deferens, seminal vesicles] and in the bladder. ERalpha was detected in non-ciliated epithelial cells in the ED, but rarely in epithelial and basal cells within the epididymis. Epithelial cells from seminal vesicles and bladder were immunonegative for ERalpha. Expression of ERalpha in stromal cells was rare in the ED, epididymis and bladder but more frequent in seminal vesicles. Expression of ERalpha, and long and short forms of ERbeta, was confirmed by Western blotting. The widespread expression of ERbeta suggests that it is the primary target for modulation of tissue function via oestrogenic ligands in the male reproductive system.

Age-, cell- and region-specific immunoexpression of estrogen receptor alpha (but not estrogen receptor beta) during postnatal development of the epididymis and vas deferens of the rat and disruption of this pattern by neonatal treatment with diethylstilbestrol

This study in rats sought to 1) characterize immunoexpression of estrogen receptor alpha (ERalpha) and ERss in the efferent ducts, epididymis, and vas deferens during postnatal development; 2) establish whether ER expression changed after neonatal treatment with diethylstilbestrol (DES); and 3) determine whether ER changes coincided with abnormal epididymal/vas development. Rats were administered 10 microg DES or vehicle on days 2, 4, 6, 8, 10, and 12 and were sampled on days 10, 18, 25, 35, and 90+. At all ages, ERalpha was immunoexpressed intensely in the efferent ducts. On day 10, immunoexpression of ERalpha was absent from the epididymis and vas, but was detectable on day 18 in epithelial cells in the caput, corpus, and proximal cauda. Epithelial expression of ERalpha was absent from the distal cauda and in the proximal and distal vas was confined to a band of periductal stromal cells. Thus, on day 18, the site of ERalpha expression delineated the epididymis-vas boundary. On days 25-35, epithelial expression of ERalpha was absent, but stromal expression persisted in the vas and distal cauda. In adults, immunoexpression of ERalpha in the epididymis and vas was absent. In contrast, ERbeta was immunoexpressed in epithelial cells and some stromal cells in the efferent ducts, epididymis, and vas at all ages. In the vas, stromal expression of ERalpha and ERbeta was in different layers. DES treatment caused 1) underdevelopment of the epididymal duct and reduced epithelial height in epididymis and vas; 2) coiling of the extraepididymal vas; 3) thickening of the periductal actin-free stromal layer in the distal cauda and vas; and 4) reduced cell proliferation on day 18 in the epididymis and vas, based on incorporation of bromodeoxyuridine, especially in the epithelium. These changes coincided with abnormalities in cell- and region-specific immunoexpression of ERalpha, but not ERbeta. Thus, in DES-treated rats on day 18, epithelial expression of ERalpha occurred in all regions of the epididymis and vas instead of being confined to the caput, corpus, and proximal cauda as in controls. Similarly, stromal ERalpha expression in the vas of DES-treated rats was not confined to a periductal layer as in controls, but occurred diffusely in the muscle layer. It is suggested that 1) estrogens play a role in peripubertal development of the epididymis and vas; 2) the cellular site of expression of ERalpha either plays a role in or reflects demarcation of the epididymal/vas boundary; and 3) blurring of this boundary in DES-treated rats coincides with altered ERalpha immunoexpression.

Marmoset spermatogenesis: organizational similarities to the human

The common marmoset (Callithrix jacchus), a small New World primate of high fecundity, is widely used in reproductive research. The aim of the present study was to determine the organization of the germ cells within the seminiferous epithelium, the duration of the spermatogenic cycle and the number of spermatogonial mitoses. Antibodies to cAMP response element modulator (CREM) and proliferating nuclear cell antigen (PCNA) and a cRNA directed against protamine P2 and morphological criteria were used to discriminate between stages of the spermatogenic cycle. Plastic sections were used to document the cell associations present in each of the nine stages of spermatogenesis. Up to five such stages could be observed within individual cross-sections of seminiferous tubules. Based on the pattern of incorporation of bromodeoxyuridine the length of the spermatogenic cycle was estimated to be 10 days and the duration of spermatogenesis to be 37 days. Four mitotic divisions were noted in spermatogonia. It is concluded that the organization of spermatogenesis in the marmoset has similarities to the human ('helical') and this makes the marmoset a suitable model for studies relevant to human testicular function.

Differential expression of estrogen receptor-alpha and -beta and androgen receptor in the ovaries of marmosets and humans

Estrogens and androgens are essential for the maturation of the ovarian follicle and normal fertility in the female. We have used antibodies specific for both forms of estrogen receptor (alpha [ERalpha] and beta [ERbeta]) and androgen receptor (AR) to investigate the pattern of receptor expression in ovaries obtained from women and from a New World primate, the Common marmoset (Callthrix jacchus). On Western blots, three antibodies directed against different peptides within human ERbeta all recognized recombinant human (h) ERbeta but did not bind to recombinant hERalpha. The ERbeta protein was extracted from human ovary and prostate and marmoset ovary. In marmoset and human ovaries, ERbeta protein was detected in the nuclei of granulosa cells in all sizes of follicle (both before and after formation of the antrum), and it was also detected in thecal cells, corpora lutea, surface epithelium, and stroma. In contrast, ERalpha protein was not detected in the nuclei of granulosa cells in preantral follicles, was low/absent from stromal and thecal cells, but was expressed in granulosa cells of antral follicles and in the surface epithelium. The pattern of expression of AR protein more closely resembled that of ERbeta than ERalpha. In conclusion, three independent antibodies have demonstrated convincingly that ERbeta is expressed in a wide range of cells in the primate ovary. Granulosa cells in preantral follicles could contain ERbeta:beta dimers. In antral follicles, however, ERalpha is also expressed, and the formation of homo- or heterodimers containing ERalpha may influence the pattern of gene activation within these cells.

Comparative effects of neonatal exposure of male rats to potent and weak (environmental) estrogens on spermatogenesis at puberty and the relationship to adult testis size and fertility: evidence for stimulatory effects of low estrogen levels

This study investigated whether neonatal exposure of male rats to estrogenic compounds altered pubertal spermatogenesis (days 18 and 25) and whether the changes observed resulted in long-term changes in testis size, mating, or fertility (days 90-100). Rats were treated neonatally with a range of doses (0.01-10 microg) of diethylstilbestrol (DES; administered on alternate days from days 2-12), a high dose of octylphenol (OP; 2 mg administered daily from days 2-12) or bisphenol A (Bis-A; 0.5 mg administered daily from days 2-12), or vehicle, while maintained on a standard soy-containing diet. The effect on the same parameters of rearing control animals on a soy-free diet was also assessed as was the effect of administering such animals genistein (4 mg/kg/day daily from days 2-18). Testis weight, seminiferous tubule lumen formation, the germ cell apoptotic index (apoptotic/viable germ cell nuclear volume), and spermatocyte nuclear volume per unit Sertoli cell nuclear volume were used to characterize pubertal spermatogenesis. Compared with (soy-fed) controls, DES administration caused dose-dependent retardation of pubertal spermatogenesis on day 18, as evidenced by decreases in testis weight, lumen formation, and spermatocyte nuclear volume per unit Sertoli cell and elevation of the germ cell apoptotic index. However, the two lowest doses of DES (0.1 and 0.01 microg) significantly increased spermatocyte nuclear volume per unit Sertoli cell. Similarly, treatment with either OP or Bis-A significantly advanced this and some of the other aspects of pubertal spermatogenesis. Maintenance of control animals on a soy-free diet also significantly advanced lumen formation and spermatocyte nuclear volume per unit Sertoli cell compared with controls fed a soy-containing diet. Administration of genistein reversed the stimulatory effects of a soy-free diet and significantly retarded most measures of pubertal spermatogenesis. In general, plasma FSH levels in the treatment groups changed in parallel to the spermatogenic changes (reduced when pubertal spermatogenesis retarded, increased when pubertal spermatogenesis advanced). By day 25, although the changes in FSH levels largely persisted, all of the stimulatory effects on spermatogenesis seen on day 18 in the various treatment groups were no longer evident. In adulthood, testis weight was decreased dose dependently in rats treated neonatally with DES, but only the lowest dose group (0.01 microg) showed evidence of mating (3 of 6) and normal fertility (3 litters). Animals treated neonatally with OP or Bis-A had normal or increased (Bis-A) testis weights and exhibited reasonably normal mating/fertility. Animals fed a soy-free diet had significantly larger testes than controls fed a soy-containing diet, and this difference was confirmed in a much larger study of more than 24 litters, which also showed a significant decrease in plasma FSH levels and a significant increase in body weight in the males kept on a soy-free diet. Neonatal treatment with genistein did not alter adult testis weight, and although most males exhibited normal mating and fertility, a minority did not mate or were infertile. It is concluded that 1) neonatal exposure of rats to low levels of estrogens can advance the first wave of spermatogenesis at puberty, although it is unclear whether this is due to direct effects of the estrogen or to associated elevation of FSH levels; 2) the effect of high doses of OP and Bis-A on these processes is essentially benign; and 3) the presence or absence of soy or genistein in the diet has significant short-term (pubertal spermatogenesis) and long-term (body weight, testis size, FSH levels, and possibly mating) effects on males.

Use of 5-bromo-4-chloro-3-indolyl-alpha-D-N-acetylneuraminic acid in a novel spot test To identify sialidase activity in vaginal swabs from women with bacterial vaginosis

The validity of measuring vaginal sialidase activity to identify bacterial vaginosis (BV) was determined by using 5-bromo-4-chloro-3-indolyl-alpha-D-N-acetylneuraminic acid in a near-patient test. The sensitivity and specificity of the test for prediction of BV were 95.6 and 96.3%, respectively. Positive and negative predictive values were 95.6 and 96.3%, respectively. This test may be an alternative to Gram staining.

Induction of progesterone receptor immunoexpression in stromal tissue throughout the male reproductive tract after neonatal oestrogen treatment of rats

Oestrogen exposure of the male during fetal/neonatal life can fundamentally alter the structure and function of the reproductive system, though how is unknown. This study examined whether such treatment was able to induce a 'female' characteristic, namely immunoexpression of progesterone receptor (PR), in the reproductive system of the male. Rats were treated on postnatal days 2, 4, 6, 8, 10 and 12 with either 10, 1 or 0.1 microg diethystilbestrol (DES) or with the vehicle (20 microl corn oil). Groups of control and treated rats were killed on days 18, 25, 35 and 90 (= adults) and tissues fixed in Bouins for immunolocalisation studies using antisera to PR (recognises A and B forms) and oestrogen receptor-beta (ER beta). PR immunoexpression was absent from all tissues studied in control rats at all ages with the exception of the parasympathetic ganglia of the prostate. In rats treated with 10 microg DES, intense immunoexpression of PR was detected in the nuclei of stromal, but not epithelial, cells of the caput and cauda epididymis, the vas deferens, seminal vesicles and at the base of the dorsolateral prostatic complex (DLPC) at day 18, but was absent from the ventral prostate and from the testis. DES induction of PR immunoexpression was evident after a single injection (on day 3) and at 18-35 days the intensity of immunoexpression was DES dose-dependent; rats treated neonatally with 0.1 microg DES showed no detectable PR immunoexpression at any age. These findings were confirmed by Western analysis which indicated that most of the PR induced was probably the B form. Co-localisation studies, using confocal microscopy, demonstrated that PR and ER beta frequently co-localised to the same stromal cells in the DLPC, epididymis and seminal vesicles of DES-treated rats at day 18, whereas epithelial cells, which also expressed ER beta, did not express PR. In the tissues studied, only occasional stromal cells expressed ER alpha in comparison to the more widespread expression of ER beta, although epithelial cell expression of ER alpha was also detected in the epididymis on day 18 (but not on day 10). In DES-treated rats, immunoexpression of PR in the reproductive tract decreased progressively in intensity from days 18-35 and was non-detectable in adulthood. In conclusion, these findings are interpreted as evidence that neonatal oestrogen treatment exerts pervasive 'reprogramming' effects throughout the reproductive system of the developing male as indicated by the induction of PR immunoexpression. This induction was restricted to stromal tissue even though both stromal and epithelial cells at most sites expressed ER beta and/or ER alpha.

Effect of neonatal gonadotropin-releasing hormone antagonist administration on sertoli cell number and testicular development in the marmoset: comparison with the rat

The primary purpose of this study was to establish whether Sertoli cells proliferate in the neonatal period in the marmoset monkey (Callithrix jacchus) and whether administration of a long-acting GnRH antagonist (GnRHa) during this phase induced any transient or permanent effects on Sertoli cell number or on any other aspect of testicular development. Male marmoset co-twins (n = 9) were treated during Weeks 1-14 with either vehicle or GnRHa. Four sets of co-twins were examined at Weeks 18-22 (start of infancy) and 5 sets in adulthood (92+ wk), and Sertoli cell number was determined using either the nucleator or optical disector methods; other testicular morphometric analyses (e.g., germ cell volume, Leydig cell volume) used standard point-counting. Data for the marmoset were compared with that obtained in similarly treated rats. Sertoli cell number in marmosets treated neonatally with GnRHa was reduced by 35% compared with that of controls at Weeks 18-22 but was comparable to control values in adulthood. However, seminiferous epithelium volume was reduced significantly in adult marmosets treated neonatally with GnRHa, and there was a tendency for reduced germ cell volume per Sertoli cell. In the same animals, there was significant expansion of the interstitium and an increase in Leydig cell volume per testis when compared with co-twin controls; a similar increase in Leydig cell volume was evident in adult rats treated neonatally with GnRHa. Comparison of Sertoli cell numbers in 6 infantile (18-24 wk) and 10 adult marmosets showed that adult numbers of Sertoli cells were present by the start of infancy but, unlike rats, marmosets were still able to replicate Sertoli cells beyond this period. However, marmoset Sertoli cells supported only approximately 20% of the germ cell volume supported by rat Sertoli cells, indicative of poor efficiency of spermatogenesis, as shown previously in the human. This finding, together with the demonstration of a temporal pattern of Sertoli cell replication similar to that in the human, supports the use of marmosets as a model for human male testicular development and function.

Diagnosis of invasive aspergillosis in bone marrow transplant recipients by polymerase chain reaction

A nested polymerase chain reaction (PCR) test targeting Aspergillus spp. large ribosomal subunit genes was evaluated retrospectively on 175 serum samples from 37 bone marrow transplant recipients, 70% of whom received grafts from unrelated donors. Six patients had proven infection, seven had probable infection, and three had possible infection, using the revised EORTC case definitions. These 16 patients were all PCR positive (57 out of 93 samples tested). Two additional patients who did not fulfil current diagnostic criteria, but in whom invasive aspergillosis (IA) was thought clinically probable, were also PCR positive (five out of nine samples). Invasive aspergillosis was unlikely in the remaining 19 patients, four of whom were PCR positive on a single occasion (four out of 70 samples). Three samples were inhibitory to PCR. Sensitivity of PCR in diagnosing patients with IA was 100%, specificity was 79% and positive predictive value was 80%, using the criterion of a single positive result. If two positive results were required, these values were 81%, 100% and 100% respectively. The median duration of infection documented by PCR was 36 days (range 3-248 days) in 17 out of 18 patients (94%) who did not survive. Positive PCR results predated the institution of antifungal therapy in two-thirds of patients. Four patients became PCR positive during pretransplant conditioning therapy.

Permanent effects of neonatal estrogen exposure in rats on reproductive hormone levels, Sertoli cell number, and the efficiency of spermatogenesis in adulthood

This study aimed to identify the mechanism(s) for impairment of spermatogenesis in adulthood in rats treated neonatally with estrogens. Rats were treated (days 2-12) with 10, 1, or 0.1 microg diethylstilbestrol (DES), 10 microg ethinyl estradiol (EE), 10 mg/kg of a GnRH antagonist (GnRHa), or vehicle and killed in adulthood. DES/EE caused dose-dependent reductions in testis weight, total germ cell volume per testis, and Sertoli cell volume per testis. Sertoli cell number at 18 days of age in DES-treated rats was reduced dose dependently. GnRHa treatment caused changes in these parameters similar to those in rats treated with 10 microg DES. Plasma FSH levels were elevated (P < 0.001) to similar levels in all treatment groups regardless of differences in Sertoli cell number and levels of inhibin B; the latter reflected Sertoli cell number, but levels were disproportionately reduced in animals treated with high doses of DES/EE. Neonatal estrogen treatment, but not GnRHa, caused dose-dependent reductions (40-80%) in plasma testosterone levels in adulthood, but did not alter LH levels. Preliminary evidence suggests that the decrease in testosterone levels in estrogen-treated rats is not due to reduced Leydig cell volume per testis. GnRHa-treated rats exhibited a significant increase in germ cell volume per Sertoli cell and a reduction in germ cell apoptosis, probably because of the raised FSH levels. Despite similar raised FSH levels, rats treated with DES (10 or 1 microg) or EE (10 microg) had reduced germ cell volume/Sertoli cell and increased germ cell apoptosis, especially when compared with GnRHa-treated animals. The latter changes were associated with an increase in lumen size per testis, indicative of impaired fluid resorption from the efferent ducts, resulting in fluid accumulation in the testis. Rats treated neonatally with 0.1 microg DES showed reduced germ cell apoptosis comparable to that in GnRHa-treated animals. The changes in apoptotic rate among treatment groups occurred across all stages of the spermatogenic cycle. It is concluded that 1) neonatal estrogen treatment results in dose-dependent alterations in Sertoli cell numbers, germ cell volume, efficiency of spermatogenesis, and germ cell apoptosis in adulthood; 2) the relatively poor spermatogenesis in estrogen-treated animals is most likely due to altered testis fluid dynamics and/or altered Sertoli cell function; 3) as indicated by FSH (LH) and testosterone levels, the hypothalamic-pituitary axis and Leydig cells are probably more sensitive than the Sertoli cells to reprogramming by estrogens neonatally; and 4) elevated FSH levels in adulthood may improve the efficiency of spermatogenesis.

Mucinase and sialidase activity of the vaginal microflora: implications for the pathogenesis of preterm labour

Evidence linking bacterial vaginosis (BV) to chorioamnionitis and spontaneous preterm birth is mounting. Successful treatment of BV could reduce the rate of late miscarriage and preterm birth. Mucinase and sialidase activity have been implicated in the pathogenesis of BV. This study extends the work of previous studies to investigate sialidase, other known mucin degrading enzymes and overall mucin degrading activity in samples of vaginal fluid from women with and without BV. Samples from 31 women were diagnosed for BV, and tested for enzyme activity using established assays. Activity was recorded in all samples. Significant increases in activity were detected in BV samples for sialidase using a mucin (BSM P<0.005) and serum type glycoprotein (AGP P<0.005) substrates, beta-galactosidase (P<0.001), and beta-N-acetylhexosaminidase (P<0.01). No significant increases in BV patients were detected in O-glycanase, proteinase, arylesterase, sulphatase or whole mucinase activities. These results support the hypothesis that certain BV-associated enzymes may detrimentally affect the mucosal barrier, permitting bacteria access to the uterus.

Activities of beta-lactams and macrolides against Helicobacter pylori

A continuous-culture system (chemostat) was used to study the activities of beta-lactam antimicrobial agents, clarithromycin, and 14-OH-clarithromycin against slowly growing Helicobacter pylori NCTC 11637. H. pylori was grown to steady state before exposure to these antimicrobial agents at x8 the MIC. The bactericidal actions of combinations of amoxicillin and clarithromycin were also studied. Viable counts (numbers of CFU per milliliter) were determined at 2-h intervals for 12 h and at 20 h after the addition of antibiotics. The effects of pH changes (6.5 to 7.4) on the activities of amoxicillin, clarithromycin, and the combination of these against H. pylori NCTC 11637 were also studied. Viable counts following exposure to ampicillin, cefixime, ceftazidime, cefuroxime, cefotaxime, azlocillin, and piperacillin at 20 h showed bacteriostatic activity. Imipenem, meropenem, amoxicillin, clarithromycin, and 14-OH-clarithromycin reduced the viable counts by 3 log10 CFU/ml (>/=99.9% killing). Imipenem was the most rapidly bactericidal against H. pylori NCTC 11637. Results of the pH experiments showed that amoxicillin was bactericidal at pHs 6.5 to 7. 4. Clarithromycin was bactericidal at pH 7.0 to 7.4 but was bacteriostatic at pH 6.5. The combination of amoxicillin and clarithromycin was bactericidal at pHs 6.5 and 7.0. A batch culture (flask system) was also used to investigate 12 strains of H. pylori for their susceptibilities to beta-lactams, clarithromycin, and/or 14-OH-clarithromycin in order to determine whether results from the chemostat model can be reproduced with batch cultures. Results of the chemostat time-kill kinetic study were reproducible in our batch culture flask system. The role of carbapenems in the eradication of H. pylori should be investigated.

Infections in adults undergoing unrelated donor bone marrow transplantation

This study retrospectively reviews infections over a 7-year period in 60 consecutive adults (median age 25 years) undergoing their first unrelated donor bone marrow transplant (UD-BMT). T-cell depletion was employed in 93%. More than half the patients had one or more severe, potentially life-threatening, infections. There was a high incidence of invasive fungal infections (Aspergillus 17, Candida four), despite the use of itraconazole or amphotericin prophylaxis. Ten Aspergillus infections occurred beyond 100 d. Two patients (11%) with invasive aspergillosis survived. Clustering of infections was noted, with invasive fungal infections significantly associated with bacteraemias (OR 3.73, P=0.06) and multiple viral infections (OR 4.25, P=0.05). There were 21 severe viral infections in 16 patients, with CMV disease occurring in four patients only; viral pneumonitis was predominantly due to 'community respiratory' viruses. Most early bacteraemias (68%) were due to Gram-positive organisms. The majority of episodes of Gram-negative sepsis were caused by non-fastidious non-fermentative bacteria, such as Pseudomonas spp. and Acinetobacter spp., historically regarded as organisms of low pathogenicity. In patients with successful engraftment and minimal graft-versus-host disease, late infections suggestive of continued immune dysfunction (shingles, recurrent lower respiratory infections, Salmonella enteritis and extensive warts) were common.

Use of a modified Robbins device to directly compare the adhesion of Staphylococcus epidermidis RP62A to surfaces

Staphylococcus epidermidis is a frequent cause of infection associated with the use of biomedical devices. Flow cell studies of the interaction between bacteria and surfaces do not generally allow direct comparison of different materials using the same bacterial suspension. The use of a modified Robbins Device (MRD) to compare the adhesion to different surfaces of Staph. epidermidis RP62A grown in continuous culture was investigated. Adhesion to glass was compared with siliconized glass, plasma-conditioned glass, titanium, stainless steel and Teflon. Attachment to siliconized glass was also compared with glass under differing ionic strength, and divalent cation concentrations. Both the differences in numbers adhering and changes in adhesion (slope) through the MRD were compared. There was a trend towards higher numbers adhering to the discs at the in-flow end of the MRD than at the outflow end, probably reflecting depletion of adherent bacteria in the interacting stream. Adhesion of Staph. epidermidis RP62A to siliconized glass and Teflon was reduced when compared to glass with increasing flow rates. Adhesion to stainless steel was not affected by flow rate and titanium gave a different slope of adhesion through the MRD when compared with glass, suggesting an interaction with different sub-populations within the interacting stream. Differences between siliconized glass and glass at flow rates of 300 ml h-1 were abolished by the addition of calcium or EDTA and reduced by the addition of magnesium. Increasing ionic strength reduced the statistical significance of the differences between glass and siliconized glass. Pre-conditioning of glass with pooled human plasma reduced adhesion compared with untreated glass and again gave a different slope to glass. The MRD linked to a chemostat can be used to compare directly bacterial adhesion to potential biomaterials. Variable depletion of the interacting stream should be taken into account in the interpretation of results. Divalent cation concentration, substrate properties and flow rate were important determinants of the comparative adhesion of Staph. epidermidis RP62A to surfaces.

Biofilm formation by Helicobacter pylori

Helicobacter pylori NCTC 11637 produces a water-insoluble biofilm when grown under defined conditions with a high carbon:nitrogen ratio in continuous culture and in 10% strength Brucella broth supplemented with 3 g l-1 glucose. Biofilm accumulated at the air/liquid interface of the culture. Light microscopy of frozen sections of the biofilm material showed few bacterial cells in the mass of the biofilm. The material stained with periodic acid Schiff's reagent. Fucose, glucose, galactose, and glycero-manno-heptose, N-acetylglucosamine and N-acetylmuramic acid were identified in partially purified and in crude material, using gas chromatography and mass spectrometry. The sugar composition strongly indicates the presence of a polysaccharide as a component of the biofilm material. Antibodies (IgG) to partially purified material were found in both sero-positive and sero-negative individuals. Treatment of the biofilm material with periodic acid reduced or abolished immunoreactivity. Treatment with 5 mol l-1 urea at 100 degrees C and with phenol did not remove antigenic recognition by patient sera. The production of a water-insoluble biofilm by H. pylori may be important in enhancing resistance to host defence factors and antibiotics, and in microenvironmental pH homeostasis facilitating the growth and survival of H. pylori in vivo.

Inhibin B levels in plasma of the male rat from birth to adulthood: effect of experimental manipulation of Sertoli cell number

Sertoli cells undergo important changes in their number and function at different ages in the rat and may be the primary source of circulating inhibin B. The aims of this study were 1) to establish the profile of inhibin B levels from birth to adulthood in normal rats and 2) to identify whether experimental manipulation of Sertoli cell numbers was able to alter this profile. Levels of inhibin B, measured by a specific two-site assay, increased fivefold in normal Wistar rats between day 3 and days 10-15, plateaued, and then declined in late puberty to reach adult levels which were approximately 60% of those observed on days 10-15. The increase in inhibin B levels in the neonatal period coincided with the period of Sertoli cell multiplication as indicated by incorporation of bromodeoxyuridine. Neonatal treatment of rats with a GnRH antagonist (GnRHa) reduced Sertoli cell number and adult testis weight by 48% and significantly reduced plasma levels of inhibin B at all ages through to adulthood. Induction of neonatal hypothyroidism in Sprague-Dawley rats by administration of propylthiouracil (PTU) up to day 25 of age increased final testis weight by 41% (indicative of increased Sertoli cell numbers) and resulted in elevation of plasma levels of inhibin B at all ages beyond 7 days of age. The degree of change in inhibin B levels in adult rats in the two experimental treatment groups was approximately proportional to the change in final testis weight. Plasma follicle-stimulating hormone (FSH) showed changes opposite to inhibin B, with levels being lowered in PTU-treated rats and elevated (beyond day 25) in GnRHa-treated animals. The present results suggest that final Sertoli cell number per testis exerts an important effect on the circulating level of inhibin B (and FSH) in the rat. These findings are compared to the emerging data for the human male.

Abnormalities in functional development of the Sertoli cells in rats treated neonatally with diethylstilbestrol: a possible role for estrogens in Sertoli cell development

Diethylstilbestrol (DES) was administered neonatally (Days 2-12; 10 microg on alternate days) to rats, and developmental changes in Sertoli cell function were evaluated at 18, 25, and 35 days of age and compared to those observed in rats administered a GnRH antagonist (GnRHa; Days 2 and 5; 10 mg/kg) or a vehicle (controls). DES and GnRHa treatments resulted in similar reductions in both Sertoli cell numbers (40% for DES, 48% for GnRHa) and suppression of testicular growth at 18 and 25 days, though by 35 days the suppression was more pronounced (p < 0.001) in DES-treated animals. Plasma FSH levels were suppressed markedly at 18 and 25 days, but not at 35 days, in GnRHa-treated rats, whereas in DES-treated rats the FSH levels were suppressed significantly only at 35 days. Both treatments suppressed plasma levels of inhibin B, though this was more pronounced (p < 0.05) in DES- than in GnRHa-treated rats. In controls, Sertoli cell immunoexpression of inhibin alpha, sulfated glycoprotein-1 (SGP-1), and androgen receptor (AR) increased in intensity and changed to an adult, stage-dependent pattern by 25 days. In GnRHa-treated rats these changes were reduced in intensity but were similar to those in controls at 35 days. In DES-treated rats, the increase in intensity and stage-dependent pattern of immunoexpression of inhibin alpha, SGP-1, and AR were virtually absent at 25 days but were present by 35 days. Germ cell volume per Sertoli cell was reduced in GnRHa- and DES-treated rats compared with controls at 18 and 25 days but was significantly greater (p < 0. 001) in DES- than in GnRHa-treated rats at 35 days. The proportion of apoptotic to viable germ cells was increased (p < 0.01) in GnRHa- and DES-treated rats compared with controls at 18 and 25 days; but at 35 days, values in GnRHa-treated rats had declined to control values whereas those for DES-treated rats remained 10-fold elevated (p < 0.001). In adulthood, testis weight and daily sperm production were reduced by 43% and 44%, respectively, in GnRHa-treated rats, but spermatogenesis was grossly normal. Comparable changes were observed in approximately 25% of DES-treated rats, but the majority exhibited > 60% reduction in testis weight with many Sertoli cell-only tubules and very low daily sperm production. Taken together, these data are interpreted as providing evidence for direct modulation of Sertoli cell (maturational) development by DES.

Absence of a post-antibiotic effect (PAE) of beta-lactams against Helicobacter pylori NCTC 11637

A continuous culture system (chemostat) was used to study the post-antibiotic effect (PAE) of beta-lactams, against slowly-growing Helicobacter pylori NCTC 11637. H. pylori was grown at one quarter of its maximum specific growth rate (mu(max)) before exposure to ampicillin, amoxycillin, azlocillin, piperacillin or cefixime (8 x MIC). After 8 h, the antibiotics were inactivated. Viable counts were used to determine the rate of recovery of H. pylori. The recovery growth rate of H. pylori was similar to the maximum growth rate of H. pylori under antibiotic-free experimental conditions, so none of the beta-lactams studied showed a PAE against slowly-growing H. pylori.

Molecular epidemiological study of Aspergillus fumigatus in a bone marrow transplantation unit by PCR amplification of ribosomal intergenic spacer sequences

We have developed a PCR-based method for the subspecific discrimination of Aspergillus fumigatus types by using two primers designed to amplify the intergenic spacer regions between ribosomal DNA transcription units. The method permitted the reproducible discrimination of 11 distinct DNA types among a total of 119 isolates of A. fumigatus collected from patients and from the environment of a bone marrow transplantation (BMT) unit over a three-year period. Ten DNA types of A. fumigatus were isolated from patients in the BMT unit; eight of these types were also found in the hospital environment, and six of these were present in the unit itself. Thirteen BMT patients developed infection with one of three DNA types some months after these had first been found in the environment of the unit. In other instances, the same DNA types of A. fumigatus were isolated from BMT patients that were later recovered from the environment of the unit. Several DNA types of A. fumigatus were found in the hospital environment over an 18-month period. Molecular typing of multiple isolates of A. fumigatus, obtained from postmortem tissue samples, showed that one patient was infected with a single DNA type, but two others had up to three different DNA types. Our findings suggest that A. fumigatus infection in BMT recipients may be nosocomial in origin and underline the need for careful environmental monitoring of units in which high-risk patients are housed.

Detection of bacteraemia in patients with fever and neutropenia using 16S rRNA gene amplification by polymerase chain reaction

Episodes of fever and neutropenia are common complications of treatment for cancer. The use of prophylactic and early empirical antibiotics has reduced mortality but decreases the sensitivity of diagnostic tests based on culture. The aim of this study was to determine the potential of a broad diagnostic approach (eubacterial) based on 16S rRNA gene amplification and sequencing to augment cultural methods of diagnosis of bacteraemia in patients with fever and neutropenia in a regional paediatric oncology centre. One hundred eleven patient-episodes of fever and neutropenia were evaluated during the study period, 17 of which were associated with positive blood cultures, as follows: Staphylococcus epidermidis (n = 6 episodes), Enterococcus faecium (n = 2), Streptococcus sanguis (n = 3), Streptococcus mitis (n = 3), Staphylococcus aureus (n = 1), Micrococcus spp. (n = 1), and Stenotrophomonas maltophilia (n = 1). Eubacterial polymerase chain reaction (PCR) detected bacterial DNA in nine of 11 blood culture-positive episodes for which a sample was available for PCR; the species identified by sequence analysis were identical to those derived from the conventional identification of the cultured isolates. Bacterial DNA was detected in 20 episodes (21 bacterial sequences) associated with negative blood cultures, 18 of which occurred in patients who were receiving antibiotics at the time of sample collection. The species presumptively identified by partial 16S rRNA gene sequencing were as follows: Pseudomonas spp. (n = 6 episodes), Acinetobacter spp. (n =5 ); Escherichia spp. (n = 3); Moraxella spp. (n = 3); Staphylococcus spp. (n = 2); Neisseria spp. (n = 1); and Bacillus spp. (n = 1). The results of this study suggest that molecular techniques can augment cultural methods in the diagnosis of bacteraemia in patients who have been treated with antibiotics.

Expression of oestrogen receptor beta (ER beta) occurs in multiple cell types, including some germ cells, in the rat testis

The identification of a second oestrogen receptor (beta) has prompted a re-evaluation of the potential sites of action of oestrogens. The aim of the present study was to characterize immunoexpression of ER beta expression in the testis to complement earlier data which had demonstrated that expression of ER alpha is confined to testicular interstitial Leydig cells. In all testes studied, including those from both fetal (day 20.5 p.c.) and adult rats, ER beta was found to be expressed in multiple cell types. Sertoli cell nuclei were immunopositive at all ages. In adult testes expression in Sertoli cells was not stage dependent and was unaffected by ablation of Leydig cells. In fetal testes ER beta was also expressed in peritubular cells, fetal Leydig cells and gonocytes. In the pubertal and adult testis ER beta was detected in the nuclei of spermatogonia and most pachytene spermatocytes. Weak immunopositive staining was present in the cytoplasm of spermatocytes undergoing the second meiotic division. In conclusion the widespread expression of ER beta in the testis is consistent with a role for oestrogens in modulating spermatogenesis, and hence fertility, in the male.

An economic perspective on policy to reduce antimicrobial resistance

Resistance to antimicrobial drugs is increasing worldwide. This resistance is, at least in part, associated with high antimicrobial usage. Despite increasing awareness, economists (and policy analysts more generally) have paid little attention to the problem. In this paper antimicrobial resistance is conceptualised as a negative externality associated with the consumption of antimicrobials and is set within the broader context of the costs and benefits associated with antimicrobial usage. It is difficult to determine the overall impact of attempting to reduce resistance, given the extremely limited ability to model the epidemiology of resistant and sensitive micro-organisms. It is assumed for the purposes of the paper, however, that dealing with resistance by reducting antimicrobial usage would lead to a positive societal benefit. Three policy options traditionally associated with environmental economics (regulation, permits and charges) are examined in relation to their potential ability to impact upon the problem of resistance. The primary care sector of the U.K.'s National Health Service provides the context for this examination. Simple application of these policies to health care is likely to be problematic, with difficulties resulting particularly from the potential reduction in clinical freedom to prescribe when appropriate, and from the desire for equity in health care provision. The paper tentatively concludes that permits could offer the best policy response to antimicrobial resistance, with the caveat that empirical research is needed to develop the most practical and efficient system. This research must be conducted alongside the required epidemiological research.

Fetal and perinatal influence of xenoestrogens on testis gene expression

The incidence of reproductive abnormalities in the male has been reported to have increased during the past 50 years. It has been suggested that these changes may be attributable to the presence of chemicals with oestrogenic activity in our environment. The aim of the experiments described in this chapter was to investigate the effects of acute exposure to high levels of xenoestrogens either indirectly during fetal life, or directly during neonatal life, on gene expression in the testis and pituitary. Fetal treatment involved administration of diethylstilbestrol (DES), 4-octylphenol (OP) or vehicle (oil, control) to pregnant rats on days 11.5 and 15.5 post coitum; fetuses were recovered on day 17.5. There was no difference between fetuses from control and treated mothers in either the overall histology of the testes or numbers of Leydig cells as determined by immunohistochemistry with an antibody directed against 3 beta-HSD. However there was a consistent and striking reduction in the amount of P450 17-a hydroxylase C17, 20 lyase (P450c17) and steroidogenic factor 1 (SF-1) detected by immunocytochemistry in testes from treatment groups given the higher doses of OP and DES. Oestrogen receptors (ER alpha) were present in the fetal leydig cells of all animals. Neonatal treatment involved direct injection of oil (control), DES, OP or Bisphenol A (Bis A) on days 2, 4, 6, 8, 10 and 12; pituitaries and testes were recovered on day 18. Testis weights and seminiferous tubule diameters were significantly reduced in animals treated with DES. In these same animals immunocytochemical localisation revealed that the amounts of FSH beta subunit and inhibin alpha subunit were reduced in their pituitaries and testes respectively. OP did not appear to have an acute, measurable effect on testis gene expression but a reduction in testis weight was noted in adult animals given the same treatment regime. The effects observed are consistent with negative feedback by oestrogens on pituitary production of FSH resulting in retarded maturation of seminiferous tubules and reduced Sertoli cell numbers. These studies have demonstrated that administration of high levels of oestrogens can affect gene expression in the testis early in life. However, the relevance of these findings to observations in man await a) a greater understanding of the physiological role(s) of oestrogens in normal males, b) an evaluation of the sources, routes of exposure, concentrations in vivo and bioavailability of xenoestrogens.

Expression cloning of a rat testicular transcript abundant in germ cells, which contains two leucine zipper motifs

The aim of the present study was to identify specific, novel germ cell markers that could be used to monitor normal and abnormal spermatogenesis. Of several cloned cDNAs isolated from an adult rat testis cDNA library using an expression screening strategy, clone 813B4 (700 base pairs) hybridized exclusively to three mRNA transcripts in samples isolated from rat testes on and after Day 21 of life and to epididymides from some, but not all, adult rats. After further screening, two identical clones encoding a 2.2-kilobase cDNA (KTT4) were isolated and found to contain an open reading frame of 578 amino acids including two leucine zipper motifs. On Northern blots, KTT4 mRNA was abundant in samples from round spermatids, and homologous mRNAs were present in testes from mice and marmosets. A zoo blot revealed that the KTT4 gene is conserved in humans, monkeys, mice, dogs, and cattle. On sections of rat testes, KTT4 mRNA was first detectable in pachytene spermatocytes at stage VII and thereafter was abundant in round and elongating spermatids until step 15. Expression of KTT4 was not altered by ethane dimethane sulphonate-induced androgen withdrawal, but in rats treated 14 days previously with methoxyacetic acid, a marked reduction in KTT4 was noted associated with the depletion of round spermatids. In conclusion, the present study identified a conserved gene expressed in meiotic and post-meiotic germ cells; database searches have shown it to be homologous to recently published sequences for an outer dense fiber protein of the sperm tail (Odf2/Odf84).

Expression of oestrogen receptor beta (ER beta) in multiple rat tissues visualised by immunohistochemistry

Steroid hormones regulate cell function via specific receptors, members of a super family of ligand activated transcription factors, expressed in their target tissues. A second oestrogen receptor (ER beta) has recently been shown by RT-PCR to have a wide tissue distribution distinct from that of oestrogen receptor alpha (ER alpha). We have raised a polyclonal antiserum using a peptide specific for ER beta in order to determine the cellular sites of expression of the receptor. In the adult rat ER beta was localised to cell nuclei in a wide range of tissues including ovary, oviduct, uterus, lung, adrenal, seminal vesicle, bladder, heart, prostate and testis. In the ovary ER beta was present in multiple cell types including granulosa cells in small, medium and large follicles, theca and corpora lutea whereas ER alpha was undetectable in these cell types. In the uterus ER beta and ER alpha were both present in epithelial cells lining the lumen and glands. In the lung ER beta was present in the cells lining the bronchioles and alveoli as well as in smooth muscle. In bladder and seminal vesicle immunostaining was intense in epithelial cells but the receptor was also expressed in nuclei of smooth muscle cells. Cell nuclei of the heart ventricle were immunopositive for ER beta as were most cells of the adult rat adrenal. In the seminiferous epithelium of the testis, nuclei of Sertoli cells were immunopositive but expression was not stage dependent. In conclusion, immunohistochemistry has proved invaluable in visualising specific sites of expression of ER beta in complex tissues including those of the reproductive tract.

Amino acid utilisation and deamination of glutamine and asparagine by Helicobacter pylori

Helicobacter pylori can utilise amino acids as the sole carbon energy source. The present study demonstrated that H. pylori grown in continuous culture in a defined medium containing glucose and amino acids utilised alanine, arginine, asparagine, aspartate, glutamine, glutamate, proline and serine. Specific asparaginase and glutaminase enzymes deaminated asparagine and glutamine respectively to aspartate and glutamate, with the production of ammonia. The glutaminase activity was inhibited by 6-diazo-5-oxo-L-norleucine. All the 13 strains of H. pylori tested produced both glutaminase and asparaginase activities. Glutamine is important in the health of the gastric and intestinal mucosa and is a primary energy source for lymphocytes. Depletion of glutamine at the site of H. pylori infection may be of significance in the pathogenesis of H. pylori-associated diseases such as peptic ulcer and gastric cancer.

Investigation of the potential role of the germ cell complement in control of the expression of transferrin mRNA in the prepubertal and adult rat testis

Iron is required for the normal development of germ cells during spermatogenesis. Because these cells have no direct access to systemic iron, there exists a shuttle system involving production and secretion of the iron-transporting protein transferrin by the Sertoli cells. Previous reports using cultures of immature Sertoli cells exposed to adult germ cells, or in vivo studies involving germ cell depleted adult rat testes, concluded that production of transferrin by Sertoli cells is modulated by germ cell complement. In the present study we have used in situ hybridisation with cRNA probes directed against the 5' and 3' ends of transferrin mRNA to examine the pattern of expression of transferrin in the immature and adult rat testis. Adult rats were treated with ethane dimethane sulphonate or methoxyacetic acid (MAA) to manipulate their testosterone levels or germ cell complement respectively. Initial findings obtained using the 3' probe showed a decrease in transferrin mRNA associated with round spermatid depletion. However, these data were not confirmed by in situ hybridisation when the 5' probe was used. The specificity of the probes was examined using Northern blotting and the 3' probe was found to hybridise to the germ cell transcript for hemiferrin even under conditions of high stringency. Examination of immature and pubertal rat testes by in situ hybridisation using the 5' transferrin-specific probe found that as early as 14 days of age the level of expression of transferrin mRNA was clearly different between tubules, and the mRNA appeared to be expressed in Leydig cells on and after day 31. In the adult rat testis, maximal expression of transferrin mRNA was found at stages VIII-XIV, calling into question the interpretation of the results of some previous studies showing expression of transferrin mRNA at all stages of the spermatogenic cycle. This stage-specific pattern of expression was not altered by acute germ cell depletion using MAA. However, Northern blot analysis showed a statistically significant increase in transferrin mRNA expression at 7 days after MAA treatment when pachytene spermatocytes were depleted from tubules at all stages of the spermatogenic cycle at which transferrin is normally expressed. In conclusion, we found that transferrin mRNA expression was not modulated by round spermatids as has been reported previously but that meiotic germ cells may influence expression of transferrin at specific stages of the spermatogenic cycle.

Eubacterial approach to the diagnosis of bacterial infection

Computed tomography revealed a frontal empyema in an 8 month old boy who presented with a prolonged convulsion. Before admission he had received oral antibiotics and all specimens were negative on culture. The presence of bacteria in cerebrospinal and empyema fluid was demonstrated using the polymerase chain reaction (PCR) with 16S rRNA gene primers. A presumptive identification of Streptococcus pneumoniae was made by comparison of PCR products with those derived from known bacteria using denaturing gradient gel electrophoresis.