The bovine foot skin microbiota is associated with host genotype and the development of infectious digital dermatitis lesions

BACKGROUND

Bovine Digital Dermatitis (BDD) is a prevalent infectious disease, causing painful foot skin lesions and lameness in cattle. We describe herein the bovine foot skin microbiota and its associations with BDD using 16S rRNA gene amplicon and shotgun metagenomic sequencing on samples from 259 dairy cows from three UK dairy farms.

RESULTS

We show evidence of dysbiosis, and differences in taxonomy and functional profiles in the bovine foot skin microbiome of clinically healthy animals that subsequently develop BDD lesions, compared to those that do not. Our results suggest that taxonomical and functional differences together with alterations in ecological interactions between bacteria in the normal foot skin microbiome may predispose an animal to develop BDD lesions. Using genome-wide association and regional heritability mapping approaches, we provide first evidence for interactions between host genotype and certain members of the foot skin microbiota. We show the existence of significant genetic variation in the relative abundance of Treponema spp. and Peptoclostridium spp. and identify regions in the bovine genome that explain a significant proportion of this variation.

CONCLUSIONS

Collectively this work shows early changes in taxonomic and functional profiles of the bovine foot-skin microbiota in clinically healthy animals which are associated with subsequent development of BDD and could be relevant to prevention of disease. The description of host genetic control of members of the foot skin microbiota, combined with the association of the latter with BDD development offer new insights into a complex relationship that can be exploited in selective breeding programmes. Video Abstract.

Snake scales record environmental metal(loid) contamination

Wetland snakes, as top predators, are becoming globally recognised as bioindicators of wetland contamination. Livers are the traditional test organ for contaminant exposure in organisms, but research is moving towards a preference for non-lethal tissue sampling. Snake scales can be used as an indicator of exposure, as many metals bind to the keratin. We used laser ablation with inductively coupled plasma-atomic emission spectroscopy and mass spectrometry (LA-ICP-MS) to quantify the concentrations of 19 metals and metalloids (collectively referred to 'metals' hereafter) in Western tiger snake (Notechis scutatus occidentalis) scales from four wetlands along an urban gradient, and compared them to concentrations measured in captive tiger snake scales. We conducted repeat measures to determine the concentration accuracy of each metal using LA-ICP-MS. Concentrations in wild Western tiger snake scales were significantly higher than in reference tiger snake scales for most metals analysed, suggesting accumulation from environmental exposure. We compared the scale concentrations to sediment concentrations of sampled wetlands, and found inter-site differences between mean concentrations of metals in scales parallel patterns recorded from sediment. Four metals (Mn, As, Se, Sb) had strong positive correlations with liver tissue contents suggesting scale concentrations can be used to infer internal concentrations. By screening for a larger suite of metals than we could using traditional digestive methods, we identified additional metals (Ti, V, Sr, Cs, Tl, Th, U) that may be accumulating to levels of concern in tiger snakes in Perth, Western Australia. This research has progressed the use of LA-ICP-MS for quantifying a suite of metals available in snake scales, and highlights the significance of using wetland snake scales as a non-lethal indicator of environmental contamination.

The dysbiosis of ovine foot microbiome during the development and treatment of contagious ovine digital dermatitis

BACKGROUND

Contagious Ovine Digital Dermatitis (CODD) is an emerging and common infectious foot disease of sheep which causes severe welfare and economic problems for the sheep industry. The aetiology of the disease is not fully understood and control of the disease is problematic. The aim of this study was to investigate the polybacterial aetiopathogenesis of CODD and the effects of antibiotic treatment, in a longitudinal study of an experimentally induced disease outbreak using a 16S rRNA gene amplicon sequencing approach.

RESULTS

CODD was induced in 15/30 experimental sheep. During the development of CODD three distinct phenotypic lesion stages were observed. These were an initial interdigital dermatitis (ID) lesion, followed by a footrot (FR) lesion, then finally a CODD lesion. Distinct microbiota were observed for each lesion in terms of microbial diversity, clustering and composition. Porphyromonadaceae, Family XI, Veillonellaceae and Fusobacteriaceae were significantly associated with the diseased feet. Veillonellaceae and Fusobacteriaceae were most associated with the earlier stages of ID and footrot rather than CODD. Following antibiotic treatment of the sheep, the foot microbiota showed a strong tendency to return to the composition of the healthy state. The microbiota composition of CODD lesions collected by swab and biopsy methods were different. In particular, the Spirochaetaceae family were more abundant in samples collected by the biopsy method, suggesting that these bacteria are present in deeper tissues of the diseased foot.

CONCLUSION

In this study, CODD presented as part of a spectrum of poly-bacterial foot disease strongly associated with bacterial families Porphyromonadaceae, Family XI (a family in Clostridiales also known as Clostridium cluster XI), Veillonellaceae and Fusobacteriaceae which are predominately Gram-negative anaerobes. Following antibiotic treatment, the microbiome showed a strong tendency to return to the composition of the healthy state. The composition of the healthy foot microbiome does not influence susceptibility to CODD. Based on the data presented here and that CODD appears to be the severest end stage of sheep infectious foot disease lesions, better control of the initial ID and FR lesions would enable better control of CODD and enable better animal welfare.

Removal of bovine digital dermatitis-associated treponemes from hoof knives after foot-trimming: a disinfection field study

Background

Bovine digital dermatitis (BDD) is an infectious foot disease found commonly in dairy herds. Foot-trimming is an important husbandry procedure for reducing the ensuing lameness; however, epidemiological, and microbiological studies have identified this as a risk activity for transmitting BDD.

Three disinfectants have previously been identified in laboratory work as effective for removing viable BDD-associated Treponema spp., from hoof knife blades. The present study enrolled 133 dairy cattle with BDD lesions, and swabbed hoof knife blades before and after foot-trimming, and after knife disinfection with one of three disinfectants (1:100 FAM30®, 2% Virkon® and 2% sodium hypochlorite) to assess their efficacy under field conditions.

Results

Detection of BDD treponeme phylogroup DNA was undertaken by direct PCR of swabs, and viable treponemes were detected by PCR of swab cultures after 6 weeks’ incubation.

Where hoof knives did not contact the lesion, BDD-associated treponemes were detected after foot-trimming in 12/22 (54.5%) cases by direct PCR and 1/22 (4.5%) cases by PCR of cultured organisms. Where contact was made with the lesion, 111/111 (100%) samples taken after trimming were positive by direct PCR and 47/118 (39.8%) were positive by culture PCR. Viable organisms were identified in cultures from lesion stages M2, M3, M4 and M4.1. No viable organisms were detected after disinfection of hoof knives.

Conclusions

Hoof knives post-trimming were frequently contaminated with BDD-associated treponeme DNA. Viable organisms were identified in cultures whether contact had been made between hoof knife and lesion or not, although contact clearly increased the frequency of detection of viable organisms. The three disinfectants tested were effective for removing viable organisms. The disinfection protocol used in this study should therefore be considered reliable for adoption as standard industry practice.

Novel ulcerative leg lesions in yearling lambs: Clinical features, microbiology and histopathology

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An outbreak of an infectious dermatological disorder of unknown aetiology in a flock of yearling lambs was investigated.

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Lesions occurred on the distal limb between the coronary band and carpel joint as a circular ulcerative dermatitis.

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Treponema spp., Dichelobacter nodosus, Staphylococcus aureus, Dermatophilus congolensis and poxvirus screens were negative.

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Fusobacterium necrophorum and Streptococcus dysgalactiae were detected in the majority of lesions examined.

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An aetiology involving bacterial infection with F. necrophorum and S. dysgalactiae was implicated.

Here we report an outbreak of an atypical, ulcerative dermatitis in North Country mule lambs, located in South Gloucestershire, UK. The lesions, which appeared to be contagious, occured between the coronary band and the carpal joint as a focal, well demarcated, circular, ulcerative dermatitis. Histopathological examination of the lesion biopsies revealed areas of ulceration, epidermal hyperplasia, suppurative dermatitis and granulation tissue. Clumped keratohyalin granules and intracellular keratinocyte oedema (ballooning degeneration) were evident within lesion biopsies, consistent with an underlying viral aetiology. A PCR-based microbiological investigation failed to detect bovine digital dermatitis-associated treponeme phylogroups, Dichelobacter nodosus, Staphylococcus aureus, Dermatophilus congolensis or Chordopoxvirinae virus DNA. However, 3 of the 10 (30 %) and 6 of 10 (60 %) lesion samples were positive for Fusobacterium necrophorum and Streptococcus dysgalactiae DNA, respectively. Contralateral limb swabs were negative by all standard PCR assays. To better define the involvement of F. necrophorum in the aetiology of these lesions, a qPCR targeting the rpoB gene was employed and confirmed the presence of F. necrophorum DNA in both the control and lesions swab samples, although the mean F. necrophorum genome copy number detected in the lesion swab samples was ∼19-fold higher than detected in the contralateral control swab samples (245 versus 4752 genome copies/μl, respectively; P < 0.001). Although we have not been able to conclusively define an aetiological agent, the presence of both F. necrophorum and S. dysgalactiae in the majority of lesions assayed supports their role in the aetiopathogenesis of these lesions.

16S rRNA amplicon sequencing reveals a polymicrobial nature of complicated claw horn disruption lesions and interdigital phlegmon in dairy cattle

Lameness represents an intractable problem for the dairy industry. Complicated claw horn disruption lesions, interdigital hyperplasia, and interdigital phlegmon are important lameness causing foot lesions. Their aetiology is multifactorial, but infectious processes are likely implicated in disease pathogenesis. Our aim was to investigate the bacterial profiles of these lesions using 16S rRNA gene sequencing of samples obtained from 51 cattle across ten farms in the UK. In this study, interdigital hyperplasia, interdigital hyperplasia with signs of interdigital dermatitis, interdigital phlegmon, complicated sole ulcers, complicated toe ulcers lesions, and complicated white line lesions were investigated; corresponding healthy skin control samples were also analysed. All diseased tissues displayed reduced microbial richness and diversity (as described by Chao1, Shannon, and Simpson alpha-diversity indices) compared to their healthy skin control samples. Our results confirm the association of Treponema spp with some of these disorders. Other anaerobic bacteria including Fusobacterium spp., Fastidiosipila spp. and Porphyromonas spp. were implicated in the aetiology of all these lesions with the exception of interdigital hyperplasia. Complicated claw horn disruption lesions, and interdigital phlegmon were found to have similar bacterial profiles. Such sharing of bacterial genera suggests many of the infectious agents detected in these foot lesions are acting opportunistically; this finding could contribute towards future treatment and control strategies.

Bovine ischaemic teat necrosis: a further potential role for digital dermatitis treponemes

A recent outbreak of ischaemic teat necrosis (ITN) on mainland UK has resulted in large economic losses for dairy farmers. Typical cases start as an area of dry, thickened and encrusted skin on the medial aspect of the base of the teat, where the teat joins the udder, often with a fetid odour. The erosion spreads down the teat, often causing intense irritation, which in turn leads to more severely affected animals removing the entire teat. Due to the severity of ITN and the substantial economic costs to the industry, analyses were undertaken to ascertain if an infectious agent might be involved in the pathology. The study has considered a role for digital dermatitis (DD) treponemes in the aetiopathogenesis of ITN because, as well as being the prime bacteria associated with infectious lameness, they have been associated with a number of emerging skin diseases of cattle, including udder lesions. A high association between presence of DD-associated treponemes and incidence of ITN (19/22), compared with absence in the control population is reported. Furthermore, sequencing of the 16S rRNA gene of treponeme isolates supports the hypothesis that the identified treponemes are similar or identical to those isolated from classical foot DD lesions in cattle (and sheep). Further studies are required to allow effective targeted prevention measures and/or treatments to be developed.

Bovine digital dermatitis: Current concepts from laboratory to farm

Bovine digital dermatitis (DD) is a severe infectious disease causing lameness in dairy cattle worldwide and is an important ruminant welfare problem that has considerable economic issues. Bovine DD is endemic in many regions worldwide and it is important to understand this major disease so that effective control strategies can be identified. There is substantial evidence that specific treponeme phylotypes play an important causative role in bovine DD. This review considers current research, including DD Treponema spp. investigations, associated DD pathobiology, and current and potential treatment and control options. Epidemiological data, alongside new microbiological data, help delineate important transmission routes and reservoirs of infection that allow effective interventions to be identified. Better on-farm housing hygiene, pasture access, routine footbathing and claw trimming with disinfected equipment need to be implemented to significantly reduce the incidence of DD. There is a paucity of peer reviewed research into both commonly used and novel treatments. In vitro antimicrobial susceptibility studies of DD treponemes and effective treatment of human treponematoses clearly indicate that antibiotics frequently selected for DD treatments are not the most efficacious. Whilst there are understandable concerns over milk withdrawal times in dairy cattle, more needs to be done to identify, license and implement more appropriate antibiotic treatments, since continued overuse of less efficacious antibiotics, applied incorrectly, will lead to increased disease recurrence and transmission. More research is needed into methods of preventing DD that circumvent the use of antibiotics, including vaccination and transmission blocking studies, to reduce or hopefully eradicate DD in the future.

A molecular epidemiology of treponemes in beef cattle digital dermatitis lesions and comparative analyses with sheep contagious ovine digital dermatitis and dairy cattle digital dermatitis lesions

Bovine digital dermatitis (BDD) is an infective foot disease commonly reported in dairy cattle where Treponema are considered as the primary causative infectious agents. There still remains little definitive information on the etiology of BDD in beef cattle suggesting further investigations are warranted. Beef BDD lesions (n=34) and healthy beef foot tissues (n=38) were analysed by PCR for three BDD-associated Treponema phylogroups and also for Dichelobacter nodosus and Fusobacterium necrophorum. Spirochete culture was attempted on all BDD lesion samples. One or more BDD-associated Treponema phylogroups were detected in 100% of beef BDD lesions. "Treponema medium/Treponema vincentii-like", "Treponema phagedenis-like" and Treponema pedis spirochetes were identified in 27/34 (79%), 31/34 (91%) and 24/34 (71%) of BDD lesions, respectively. No BDD-associated treponeme DNA was amplified from beef healthy foot tissues. D. nodosus and F. necrophorum were present in 24/34 (71%) and 15/34 (44%) of lesions and 10/38 (26%) and 12/38 (32%) of healthy foot tissues, respectively. Twenty spirochetes were isolated from beef BDD lesions; 19 were representatives of the three BDD-associated Treponema phylogroups. One spirochete isolate shared less than 97% 16S rRNA gene similarity to the three cultivable BDD-associated Treponema phylogroups and therefore may represent a novel taxa of Treponema. Upon comparison, sheep contagious ovine digital dermatitis (CODD), dairy cattle and beef cattle BDD lesions appear to have extremely similar bacteriological data and therefore provides evidence of a shared etiopathogenesis posing concerns for cross-species transmission.

Digital dermatitis treponemes associated with a severe foot disease in dairy goats

A UK dairy goat herd was assessed after reports of a severe lameness problem of unknown aetiology. A lameness prevalence estimate was produced and individual clinical examination of 15 randomly selected lame goats was performed. Fifteen animals had foot lesions closely resembling contagious ovine digital dermatitis (CODD) in sheep. Eight of the goats examined presented with typical CODD lesions and seven showed what appeared to be a more severe CODD with under-running of the sole. Ten biopsy samples were obtained from the foot lesions and tested by PCR for the three previously isolated digital dermatitis (DD) Treponema phylogroups and culture of treponemes was attempted. Ninety per cent of the biopsy samples were positive for Treponema medium/Treponema vincentii-like spirochaetes and Treponema phagedenis-like DD spirochaetes and 80per cent were positive for Treponema pedis. Spirochaetes were successfully isolated from 50 per cent of lesion samples. Three isolates were identified as belonging to the T. phagedenis-like spirochaetes and two were identified as T. pedis. The frequent isolation of similar treponemes to those isolated from bovine digital dermatitis and CODD lesions and the identification of these DD-associated phylotypes in the vast majority of lesions support the hypothesis that this novel foot condition is associated with infection by DD treponemes, and given the similarities to CODD, it suggests a causal role.

Presence of digital dermatitis treponemes on cattle and sheep hoof trimming equipment

Digital dermatitis (DD) is an infectious foot disease causing severe lameness in dairy cattle (worldwide) and sheep (UK). This study investigated whether DD Treponema phylogroups can be present on equipment used to trim ruminant hooves and, therefore, consider this trimming equipment as a possible vector for the transmission of DD. Equipment was tested after being used to trim DD symptomatic and asymptomatic cattle and sheep hooves, and subsequently after disinfection of equipment. After trimming, 'Treponema medium/Treponema vincentii-like', 'Treponema phagedenis-like' and 'Treponema denticola/T putidum-like' DD spirochaetes, were shown to be present on 23/37 (62%), 21/37 (57%) and 20/37 (54%) of knives, respectively. After disinfection, detection rates for the DD treponemes were 9/37 (24%), 6/37 (16%) and 3/37 (8%), respectively. Following culture of a swab, an isolate belonging to the T phagedenis-like spirochaetes was identified from a knife sample after trimming a DD positive cow. No isolates were obtained from knife samples after disinfection. This new data has, for the first time, identified treponemes in the farm environment, and highlighted disinfection of hoof trimming equipment between animals and between farms, as a logical precaution to limit the spread of DD.

Identifying host pathogenic pathways in bovine digital dermatitis by RNA-Seq analysis

Digital dermatitis is a painful foot disease compromising welfare in dairy cattle. The disease has a complex multibacterial aetiology, but little is known about its pathogenesis. In this study, gene expression in skin biopsies from five bovine digital dermatitis lesions and five healthy bovine feet was compared using RNA-Seq technology. Differential gene expression was determined after mapping transcripts to the Btau 4.0 genome. Pathway analysis identified gene networks involving differentially expressed transcripts. Bovine digital dermatitis lesions had increased expression of mRNA for α2-macroglobulin-like 1, a protein potentially involved in bacterial immune evasion and bacterial survival. There was increased expression of keratin 6A and interleukin 1β mRNA in bovine digital dermatitis lesions, but reduced expression of most other keratin and keratin-associated genes. There was little evidence of local immune reactions to the bacterial infection present in lesions.

Association between bovine digital dermatitis treponemes and a range of 'non-healing' bovine hoof disorders

This study describes the association between bovine digital dermatitis (BDD) treponemes and three 'non-healing' bovine hoof horn lesions, namely, 'toe necrosis' (TN), 'non-healing white line disease' (nhWLD) and 'non-healing sole ulcer' (nhSU), which are disorders that involve penetration through the horn capsule to involve the corium. In this study, these non-healing disorders (n=44) were identified as foot lesions that exhibited a topical granular appearance, exuded a typical pungent smell, were severely painful to the animal involved, and typically originated from farms where BDD is endemic. Given the similarities between these 'non-healing' lesions and BDD, the authors subjected samples of diseased tissue to PCR assays to detect the presence of DNA of BDD treponemes. All the three characterised BDD treponeme groups were identified as present together in 84.2, 81.3 and 55.6 per cent of samples of TN (n=19), nhWLD (n=16) and nhSU (n=9), respectively. In contrast, healthy control horn samples from similar sites (n=16) were PCR-negative for the BDD treponemes. Hence, these non-healing hoof lesions were strongly associated with BDD treponemes. Samples from typical heel horn erosions (n=9) were also subjected to BDD treponeme PCR assays and no association could be identified between the BDD treponemes and this horn manifestation.

Variation in rates of severe retinopathy of prematurity among neonatal intensive care units in the Australian and New Zealand Neonatal Network

AIM

To analyse variations in rates of severe retinopathy of prematurity (ROP) among neonatal intensive care units (NICUs) in the Australian and New Zealand Neonatal Network (ANZNN), adjusting for sampling variability and for case mix.

METHODS

25 NICUs were included in the study of 2105 infants born at less than 29 weeks in 1998 and 1999, who survived to 36 weeks post-menstrual age and were examined for ROP. The observed NICU rates of severe ROP were adjusted for case mix using logistic regression on gestation, weight for gestational age and sex, and for sampling variability using shrinkage estimates. The corrected rate in the best 20% of NICUs was identified and NICU variations in rates were compared with those in 2000-1.

RESULTS

The overall (unadjusted) rate of severe ROP in the NICUs was 9.6% (interquartile range 5.4-12.8%). After adjusting for both case mix and sampling variability there remained significant variation among the NICUs. 20% of NICUs had a rate of severe ROP </=5.9%. Variation in rates among NICUs showed a similar pattern in both time periods. If the overall network rate was reduced to 5.9%, the 20th centile of the adjusted rates, there would be 79 fewer cases in a 2 year period, in contrast with 26 fewer if rates in the two units with excess rates improved to the average.

CONCLUSIONS

Considerable variation in rates of severe ROP among NICUs remained after adjustment for case mix and sampling variability. These data will facilitate investigation of potentially better practices associated with a reduced risk of severe ROP.

Prenatal predictors of chronic lung disease in very preterm infants

OBJECTIVE

To identify prenatal risk factors for chronic lung disease (CLD) at 36 weeks postmenstrual age in very preterm infants.

POPULATION

Data were collected prospectively as part of the ongoing audit of the Australian and New Zealand Neonatal Network (ANZNN) of all infants born at less than 32 weeks gestation admitted to all tertiary neonatal intensive care units in Australia and New Zealand.

METHODS

Prenatal factors up to 1 minute of age were examined in the subset of infants born at gestational ages 22-31 weeks during 1998-2001, and who survived to 36 weeks postmenstrual age (n = 11 453). Factors that were significantly associated with CLD at 36 weeks were entered into a multivariate logistic regression model.

RESULTS

After adjustment, low gestational age was the dominant risk factor, with an approximate doubling of the odds with each week of decreasing gestational age from 31 to less than 25 weeks (trend p<0.0001). Birth weight for gestational age also had a dose-response effect: the lower the birth weight for gestational age, the greater the risk, with infants below the third centile having 5.67 times greater odds of CLD than those between the 25th and 75th centile (trend p<0.0001). There was also a significantly increased risk for male infants (odds ratio 1.51 (95% confidence interval 1.36 to 1.68), p<0.0001).

CONCLUSIONS

These population based data show that the prenatal factors low gestational age, low birth weight for gestational age, and male sex significantly predict the development of chronic respiratory insufficiency in very preterm infants and may assist clinical decision about delivery.

The Excess of Strokes in Female Patients after CEA is due to their Increased Thromboembolic Potential—Analysis of 775 Cases

INTRODUCTION

Women suffer an excess of complications following arterial surgery, including an increased stroke risk following CEA. In order to investigate this further we studied men and women's thromboembolic potential following CEA.

METHOD

Analysis of prospectively collected data on 775 consecutive CEAs performed between October 1995 and October 2001, to identify the number of microembolic events detected following CEA.

RESULTS

Overall women had a 2.2 fold increase in the number of postoperative emboli detected (95% CI 1.2-3.3). Of those patients with significant numbers of postoperative emboli (>25), 68% were female against 22% for men (p=0.009). In order to prevent progression onto postoperative thrombotic stroke 9.7% of women were treated with intravenous Dextran-40 therapy, as opposed to only 2.7% of men (p=0.013). There were no significant differences between men and women's preoperative risk factors and/or factors relating to their operation.

CONCLUSION

It is possible that women's excess of postoperative complications following arterial surgery is related to their apparent increased thromboembolic potential following acute arterial injury.

Effect of cutting flute design on cortical bone screw insertion torque and pullout strength

OBJECTIVE

To determine the effect of the number and length of cutting flutes on the insertion torque and pullout strength for self-tapping 4.5-millimeter cortical bone screws.

DESIGN

Screws were self-tapped in the diaphysis of human cadaver femurs. Each of the six screw types studied had different designs with varying cutting flute lengths and numbers. Bone mineral density, insertion torque, and pullout strength were measured.

SETTING

The study was conducted at an experimental biomechanics laboratory associated with a university medical center.

OUTCOME MEASUREMENTS

Insertion torque and pullout strength were normalized by the local bone mineral density.

RESULTS

The mean normalized insertion torque of the design with four full-length cutting flutes was less than the design with three full-length flutes and the two designs with one-third length flutes (p < 0.05). The mean normalized pullout strength of the screw with four full-length flutes was significantly greater than that of all screws with fewer than three flutes (p < 0.05).

CONCLUSIONS

Priorities for a cutting flute design should ideally include ease of screw insertion, minimal soft tissue irritation, and maximal screw holding power. Screws with more than two flutes were easier to insert and did not cause cortical damage during insertion. The screw with four full-length flutes showed a trend toward being the easiest to insert and having the greatest holding strength.

Osmium isotope constraints on ore metal recycling in subduction zones

Veined peridotite xenoliths from the mantle beneath the giant Ladolam gold deposit on Lihir Island, Papua New Guinea, are 2 to 800 times more enriched in copper, gold, platinum, and palladium than surrounding depleted arc mantle. Gold ores have osmium isotope compositions similar to those of the underlying subduction-modified mantle peridotite source region, indicating that the primary origin of the metals was the mantle. Because the mantle is relatively depleted in gold, copper, and palladium, tectonic processes that enhance the advective transport and concentration of these fluid soluble metals may be a prerequisite for generating porphyry-epithermal copper-gold deposits.

New electrochemical techniques for probing phase transfer dynamics at dental interfaces in vitro

Phase transfer reactions such as dissolution, precipitation, sorption, and desorption are important in a wide range of processes on dental hard tissue surfaces. An overview is provided of several new complementary electrochemical techniques which are capable of probing the dynamics of such processes at solid/liquid interfaces from millimeter- to nanometer-length scales, with a variable time resolution down to the sub-millisecond level. Techniques considered include channel flow methods with electrochemical detection, which allow reactions at solid/liquid interfaces to be studied under well-defined and calculable mass transport regimes. Scanning electrochemical microscopy allows the chemical activity of interfaces to be mapped at higher spatial and temporal resolutions. This technique, which utilizes a scanning ultramicroelectrode, has been used extensively for the study of dissolution processes of ionic crystals, as well as in imaging the action of fluid-flow-blocking agents on dentin surfaces, which act via precipitation. So that interfaces at the nanometer level can be probed, an integrated electrochemical-atomic force microscope has been developed which enables the local solution conditions to be controlled electrochemically while topographical changes are mapped simultaneously.

Relative importance of success in sport and schoolwork

Cross-domain studies of achievement-related cognitions have been gaining attention in the United States. This study provides comparative data from a United Kingdom upper school. 390 subjects age 13 (n = 218) or 15 (n = 172) years rated the importance of success in sport and schoolwork. Academic success was more important than sport success, and sport success was more important to boys (n = 203) than girls (n = 187). Academic success was less important to older subjects, and sport success was less important to older girls. Predictions, from importance and perceived ability, of free time spent in each domain were stronger for sport than for schoolwork indicating that the model held better for voluntary activity.

The role of total parenteral nutrition in critical illness: guidelines and recommendations

Critically ill patients experience a multitude of metabolic derangements in response to sepsis, shock, and severe injury. The result of extreme stress is characterized by alterations in carbohydrate and fat metabolism and persistent catabolism of lean body mass. Total parenteral nutrition is an important therapeutic modality in the care of critically ill patients. In this article, the author identifies the patient at risk, defines the appropriate time to initiate parenteral nutrition, and outlines current recommendations for energy and protein prescription. The author also briefly reviews administration issues, discusses possible complications of therapy, and defines effective strategies to monitor the response to therapy.

Estimates of population smoking prevalence: self-vs proxy reports of smoking status

OBJECTIVES

In the face of rising costs of surveillance systems, it is time to reexamine the feasibility of including proxy respondents in surveys designed to provide population estimates of smoking prevalence.

METHODS

Data are from the California. Tobacco Surveys, which are random-digit dialed telephone surveys. One adult provided demographic information and smoking status for all household residents. Additionally, some adults were selected for in-depth interviews that also included smoking status questions. We matched information from proxy respondents and self-respondents and evaluated smoking status discrepancies between them relative to demographic and other factors (n = 2930 matched pairs) in 1992. We address the potential bias these discrepancies might introduce into the population estimate of smoking prevalence.

RESULTS

Overall, the discrepancy between proxy report and self-report was 4.3%, and it increased particularly when the self-respondent reported nondaily smoking or recent quitting. Discrepancies acted in both directions, and the net bias was that the screener survey overestimated smoking prevalence by 0.1% in 1992 (0.3% in 1990).

CONCLUSIONS

Smoking status questions can be added to ongoing surveys such as the census or labor force surveys; one adult could provide smoking status for all household members.

Systemic inflammatory response syndrome, sepsis, and nutritional support

This article reviews the metabolic alterations that occur in SIRS and sepsis and the management of these patients nutritionally. Practical clinical assessment parameters that can be used by the critical care nurse to determine the nutritional and metabolic needs of the patient are presented. Issues related to enteral and parenteral routes of delivery are presented, and a discussion of disease-specific nutritional formulas is included. An understanding of the determination of metabolic and nutrition needs and the provision of adequate support to meet those needs are vital to the care of the hypermetabolic septic patient.

Doppler assessment of pulmonary artery pressure during recovery from hyaline membrane disease

The changes in pulmonary artery pressure during recovery from hyaline membrane disease were studied by serial Doppler echocardiography on 37 preterm infants. Pulmonary artery pressure was assessed noninvasively by its inverse relationship with the ratio of pulmonary artery Doppler time to peak velocity and right ventricular ejection time. The pattern of rise in ratio after the acute phase of hyaline membrane disease divided into three types. In 25 infants the ratio returned to the normal range: in 12 (group 1) at the same time as the fractional inspired oxygen fell below 0.5 and in 13 (group 2) after a delay of at least 24 hours. In 12 infants (group 3) the ratio remained below the normal range during their hospital stay, suggesting pulmonary artery pressure remained high. Infants in group 3 were of significantly lower gestation and required oxygen treatment for significantly longer than infants in groups 1 and 2. Persistently raised pulmonary pressures in group 3 may reflect lung damage either directly affecting pulmonary vasculature or exerting a secondary effect on pulmonary vascular resistance through hypoxaemia.

Doppler assessment of pulmonary artery pressure and extrapulmonary shunting in the acute phase of hyaline membrane disease

The natural history of pulmonary artery pressure and extrapulmonary shunting in acute hyaline membrane disease was studied by serial Doppler echocardiography in 57 preterm infants, 38 with, and 19 without, hyaline membrane disease. Pulmonary artery pressure was assessed non-invasively by its inverse relationship with the ratio of pulmonary artery Doppler time to peak velocity: right ventricular ejection time. The mean ratio was significantly lower in the infants with hyaline membrane disease. The mean ratio for each infant with hyaline membrane disease varied widely and did not correlate with criteria of maturity or severity of disease. Individual ratios correlated with arterial pH. Between 60-80 hours after birth, 14 of 18 infants with hyaline membrane disease (78%) and one of 19 without (5%) had patent ductus arteriosus. Left to right and bidirectional shunting at ductal and atrial level were common; pure right to left shunting was uncommon. The mean ratio seen with bidirectional shunting was significantly lower than that seen with left to right shunting. Ratios and patterns of extra pulmonary shunting were similar when the fractional inspired oxygen (FIO2) was greater than 0.9 compared with when it was less than 0.9. Pulmonary artery pressure is high during the acute phase of hyaline membrane disease but varies widely among infants. A few infants have extrapulmonary right to left shunting, and these infants are difficult to detect clinically.

The effectiveness of coma arousal intervention

Thirty-one patients who were in coma or persistent vegetative state two weeks after sustaining a severe head injury were entered into a coma arousal programme. The coma arousal protocol called for a sequence of vigorous multisensory stimulations to be applied to the patient by a relative for up to eight hours a day for seven days a week. An independent study team monitored two patient outcomes, the time taken to obey a simple command on two consecutive occasions 24 hours apart and patients' score on the Glasgow Outcome Scale 10-12 months post-injury. Outcomes were compared with an historical reference group chosen from the literature, consisting of 135 similarly classified patients. Differences between the pilot study and the reference group patients on initial characteristics suggested that the pilot study patients might have the more favourable outcomes, independent of treatment effect. The sample size was sufficient to detect a 40% improvement in recovery rate. No significant improvements were noted in either the time to obey a simple command (p greater than 0.2) or in the Glasgow Outcome Scale (p greater than 0.25), although the observed difference in the latter group was 11% in favour of the pilot study patients. This study was unable to find any evidence that coma arousal, for all its arduous patient contact, had a markedly better outcome compared with conventional treatment.

Postnatal circulatory adaptation in healthy term and preterm neonates

Thirty seven healthy infants (18 born at full term and 19 preterm) were studied serially with cross sectional and Doppler echocardiography to compare their postnatal circulatory adaptation. Pulmonary artery pressure was assessed by its inverse relationship with the ratio of pulmonary artery time to peak velocity and right ventricular ejection time measured from Doppler waveform. Patency of the ductus arteriosus and interatrial shunting were assessed by imaging and Doppler ultrasound. The ratio rose after birth in all infants; it rose more slowly in the preterm infants. After 6 hours of age the mean was significantly less in the preterm group, the greatest difference being between 25 and 36 hours. By 73 to 96 hours the difference was no longer significant. There was a trend towards later ductal closure in the preterm infants but this was not significant. Atrial shunting level varied, but some left to right shunting was seen in all infants satisfactorily studied. Pulmonary artery pressure seems to fall more slowly after preterm birth even in the absence of respiratory problems, but ductal shunting persisting for more than three days is unusual in healthy preterm infants.

Paediatric intensive care in a district general hospital

Five years' experience of paediatric intensive care in a district general hospital were analysed retrospectively. A total of 54 infants and children required respiratory support during this time--21 on a high dependency area of the children's ward and 33 on a general intensive care unit. Forty two (78%) of the patients survived, and 33 (61%) of the patients required respiratory support within four hours of admission, thus the experience of the local paediatric and anaesthetic team was crucial to the management of these children. Good intensive care for children can be provided within a district general hospital.

Urinary excretion of epidermal growth factor in the newborn

Urinary epidermal growth factor (EGF) excretion was studied serially in 36 newborn infants, from 26 to 40 weeks gestation, from birth to three months of age. All infants excreted EGF from birth. Excretion was significantly higher in term infants than in preterm infants at birth; in term infants excretion rose steadily in early infancy and there was a similar but delayed rise in EGF excretion by preterm infants. Urinary EGF excretion appears to be related to age from conception and birth does not influence it. There was no correlation between urinary EGF excretion and the rapid maturation of the lungs and skin which occurs in preterm infants in the early neonatal period.

Reduction of skin damage from transcutaneous oxygen electrodes using a spray on dressing

A spray on, copolymer acrylic dressing (Op-Site) was used to limit the skin damage caused by a transcutaneous oxygen electrode and its adhesive ring. Two identical electrodes were applied to the abdominal skin of 10 preterm infants, one on untreated skin, the other after application of Op-Site. It was found that Op-Site prevented the epidermal damage (as measured by transepidermal water loss) that occurs when the adhesive ring is removed from untreated skin. It did not interfere with transcutaneous oxygen measurements; absolute values and response times were unchanged. Op-Site is therefore useful in preventing the skin trauma that occurs when transcutaneous oxygen monitoring is being performed in preterm infants below 30 weeks' gestation in the first week of life. Care must be taken, however, to prevent a build up of Op-Site--it should be applied as a single layer, allowed to dry, and removed after use.

Percutaneous respiration in the newborn infant

Percutaneous respiration was studied in 27 newborn infants (birth weight 0.96 to 4.43 kg, gestation 27 to 40 weeks) using a closed skin cell attached to the upper abdomen into which saturated air at 37 degrees C was introduced. Gas exchange across the skin was found to be strongly related to gestational age. Term infants had lower rates of gas exchange than found across adult skin (mean O2 absorption 32.0 vs 62.0 ml/m2/hr, mean CO2 excretion 40.5 vs 86.5 ml/m2/hr). In the first few days of life infants of less than 31 weeks gestation had rates of gas exchange five to six times higher (mean O2 absorption 178.4 ml/m2/hr, mean CO2 excretion 214.8 ml/m2/hr) than those in term infants, but these fell rapidly toward term levels by 2 weeks of age. Gas exchange correlated well with skin water loss, suggesting that the epidermal barrier limits both processes. There was a linear increase in skin O2 absorption as the O2 concentration in the skin cell increased. We estimate that if in the early neonatal period an infant of less than 31 weeks gestation were nursed naked in 40% oxygen, about 13% of total resting oxygen requirements could be obtained through the skin. Under certain limited circumstances, percutaneous oxygen delivery might be clinically useful.

Development of the epidermis in the newborn

Histological development of the epidermis was studied on skin samples from 169 infants (gestation 24-40 weeks, age up to 1 year). Gestation markedly influenced epidermal development. Before 30 weeks, the epidermis is thin, has few cell layers and a poorly formed stratum corneum, but by 34 weeks it has largely matured. Postnatal influence on epidermal development is marked in the preterm infant, so that histologically the epidermis of the most immature infant resembles that of a term infant by 2 weeks of age. These changes in histology exactly parallel the development of the barrier properties of newborn skin.

Percutaneous administration of theophylline in the preterm infant

The preterm infant's skin is a poor barrier to the absorption of chemical agents. The possibility of turning this to the infant's advantage was explored by using the percutaneous route to administer theophylline. A standard dose of theophylline gel, equivalent to 17 mg anhydrous theophylline, was applied to an area of skin 2 cm in diameter over the upper abdomen under an occlusive dressing, and serial theophylline levels were measured; 25 studies were performed in 20 infants of less than or equal to 30 weeks gestation. Therapeutic theophylline levels (greater than 4 mg/L) were achieved in 11 of 13 infants who had not previously received the drug, and were maintained for up to 72 hours. In 12 studies in infants who were previously receiving aminophylline intravenously, theophylline levels were maintained for up to 70 hours. There was a significant decline in the amount of theophylline absorbed in the first 24 hours after application as the infant's postnatal age increased, but satisfactory blood levels were achieved in infants up to 20 days of age. The percutaneous route is a feasible method of administering theophylline in preterm infants.

Mortality and late-onset affective disorder

Psychiatric illness is associated with increased morbidity and mortality from physical illness. A particular association between depression and reduced expectation of life in males has been previously noted. If depression is a manifestation of incipient fatal illness, it might be predicted that those who had not previously been depressed would be at greater risk of dying in the next few years. This was not confirmed in a 5-year follow-up study, which found a higher overall mortality from natural causes in male patients with both late and early onset of depression.

Cortical neuronal counts in normal elderly controls and demented patients

The purposes of the investigation were to determine whether there was significant neuronal loss in dementia, and if so, whether it was general or localised, and to examine the relationship between neuronal counts, senile plaques and neurofibrillary change. Neuronal counts were made in nine cortical areas in the brains of 25 patients with senile dementia of the Alzheimer type and twenty-five age-matched controls, with the aid of an image analysing computer. Neuronal counts per square millimetre were significantly lower in the demented group of patients in the inferior frontal and superior temporal gyri. Neuronal counts in four columns of cortex were significantly reduced in superior, middle and inferior frontal gyri, cingulate gyrus and superior and middle temporal gyri. There was no significant difference in the parietal (Brodmann area 7) or occipital (Brodmann area 17) cortex. Corresponding glial counts per square millimetre show a significant increase in the demented group only in the middle and inferior temporal gyri. Neuronal counts correlated weakly but significantly with plaque counts in the same cortical area in the middle frontal gyrus and the superior and middle temporal gyri. High correlations between neuronal counts and estimates of neurofibrillary change were found in superior, middle and inferior frontal gyri, cingulate gyrus and superior and middle temporal gyri.

Determination of selenium in biological samples by gas-liquid chromatography with electron-capture detection

Selenium can be determined quantitatively in biological samples after nitric acid-magnesium nitrate digestion and formation of 5-nitropiazselenole, by extraction into toluene for gas-liquid chromatography with electron-capture detection. The method is suitable for the determination of selenium in orchard leaves, bovine liver and human placenta, hair, blood and urine.

Ehe incidence of cancer among in-patients with affective disorders

Mortality rates in psychiatric patients have been reported as higher than those of the general population in Scandinavia (Odegaard, 1952), the United States (Gorwitz et al., 1966; Babigian and Odoroff, 1968), and Scotland (Innes and Millar, 1970). These findings may be related both to a greater prevalence of physical disease amongst psychiatric patients (Kay and Roth, 1955; Culpan et al., 1960; Shepherd et al., 1964; Kay and Bergman, 1966; Eastwood and Trevelyan, 1972) and to a greater frequency of suicide (Stenstedt, 1952; Stenstedt, 1959; Pokorny, 1964).

A Search for the 1 10 ← 1 11 Transition of Interstellar Thioformaldehyde

A search has been made for the 1(10) <-- 1(11) transition of thioformaldehyde in interstellar clouds where formaldehyde is known to exist. Failure to detect this transition indicates that the ratio of thioformaldehyde abundance to that of formaldehyde is probably less than the abundance ratio of sulfur to oxygen.