Patient outcomes following transfer between intensive care units during the COVID-19 pandemic

Transferring critically ill patients between intensive care units (ICU) is often required in the UK, particularly during the COVID-19 pandemic. However, there is a paucity of data examining clinical outcomes following transfer of patients with COVID-19 and whether this strategy affects their acute physiology or outcome. We investigated all transfers of critically ill patients with COVID-19 between three different hospital ICUs, between March 2020 and March 2021. We focused on inter-hospital ICU transfers (those patients transferred between ICUs from different hospitals) and compared this cohort with intra-hospital ICU transfers (patients moved between different ICUs within the same hospital). A total of 507 transfers were assessed, of which 137 met the inclusion criteria. Forty-five patients underwent inter-hospital transfers compared with 92 intra-hospital transfers. There was no significant change in median compliance 6 h pre-transfer, immediately post-transfer and 24 h post-transfer in patients who underwent either intra-hospital or inter-hospital transfers. For inter-hospital transfers, there was an initial drop in median PaO₂ /F_I O₂ ratio: from median (IQR [range]) 25.1 (17.8-33.7 [12.1-78.0]) kPa 6 h pre-transfer to 19.5 (14.6-28.9 [9.8-52.0]) kPa immediately post-transfer (p < 0.05). However, this had resolved at 24 h post-transfer: 25.4 (16.2-32.9 [9.4-51.9]) kPa. For intra-hospital transfers, there was no significant change in PaO₂ /F_I O₂ ratio. We also found no meaningful difference in pH; PaCO₂ ;_, base excess; bicarbonate; or norepinephrine requirements. Our data demonstrate that patients with COVID-19 undergoing mechanical ventilation of the lungs may have short-term physiological deterioration when transferred between nearby hospitals but this resolves within 24 h. This finding is relevant to the UK critical care strategy in the face of unprecedented demand during the COVID-19 pandemic.

Persisting Symptomatic Severe Secondary Mitral Regurgitation in Heart Failure Patients

Aims We aimed to assess the rate of persisting severe symptomatic secondary mitral regurgitation (MR) in a newly diagnosed heart failure (HF) population following optimisation of guideline directed medical therapy (GDMT), cardiac resynchronisation therapy (CRT) and revascularisation. Methods We assessed all new patients referred to our hospital group’s HF clinics. We retrospectively reviewed these patients at HF clinic enrolment, HF programme completion, as well as most recent follow up. Results Of the 242 new patients referred to our HF clinics, there were 10 patients (4.1%) who had either persisting symptomatic severe secondary MR at HF programme completion, or had undergone mitral valve surgery. There were no percutaneous mitral valve repairs at the time of these patients’ referrals. The rates of ACE/ARB/ARNI, BB and MRA use were 87.8%, 94.1%, and 49.8% in those with mid ranged, or reduced ejection fraction. The rates of ICD and CRT therapy were 15.1% and 4.4% at follow up. Patients with severe MR had higher time adjusted rates of death or hospitalization for heart failure. Conclusion In a well-treated newly diagnosed HF population, repeat assessment at HF programme completion suggests 4.1% of patients have a persisting indication for percutaneous mitral valve repair based on persisting severe symptomatic secondary MR.

The Brucella suis IbpA heat-shock chaperone is not required for virulence or for expression of the VirB type IV secretion system VirB8 protein

Brucella suis, facultative intracellular bacterial pathogen of mammals, and Agrobacterium tumefaciens, a plant pathogen, both use a VirB type IV secretion system (T4SS) to translocate effector molecules into host cells. HspL, an α-crystalline-type small heat-shock protein, acts as a chaperone for the Agrobacterium VirB8 protein, an essential component of the VirB system. An Agrobacterium mutant lacking hspL is attenuated due to a misfunctional T4SS. We have investigated whether IbpA (BRA0051), the Brucella HspL homologue, plays a similar role. Unlike HspL, IbpA does not interact with VirB8, and an IbpA mutant shows full virulence and no defect in VirB expression. These data show that the Brucella α-crystalline-type small heat-shock protein IbpA is not required for Brucella virulence.

SIGNIFICANCE AND IMPACT OF STUDY

Many bacteria use type IV secretion systems (T4SS), multi-protein machines, to translocate DNA and protein substrates across their envelope. Understanding how T4SS function is important as they play major roles in the spread of plasmids carrying antibiotic resistance and in pathogenicity. In the plant pathogen Agrobacterium tumefaciens, HspL, an α-crystalline-type small heat-shock protein, acts as a chaperone for the essential type IV secretion system component VirB8. Here, we show that this is not the case for all T4SS; in the zoonotic pathogen Brucella suis, IbpA, the protein most related to HspL, does not play this role.

Effect of pattern of lymphocyte infiltration in NSCLC on outcome

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Background: The role played by the immune system in determining survival in non-small-cell lung cancer (NSCLC) is unclear. The aim of this study was to investigate the prognostic significance of T-lymphocyte infiltration in NSCLC focusing on CD3+, cytotoxic CD8+ and FOXP3+ T regulatory (Treg) cells. Methods: Immunohistochemistry was used to detect CD3+, CD8+ and FOXP3+ lymphocytes in the tumor islets and tumor stroma in 186 patients with surgically resected NSCLC with a minimum follow-up of 3 years. Quantification of immune infiltration was performed using the Aperio automated image analysis system incorporating the Genie software tool. The median of tumor:stroma CD3+, CD8+ and FOXP3+ infiltration ratios were used as thresholds to dichotomise patients to either high or low infiltration rates. Prognostic variables were identified using univariate and Cox multivariate analysis. Kaplan-Meier analysis and the log-rank test were used to illustrate differences in overall survival. Results: Patients with a higher intratumoral CD3+ and CD8+ lymphocyte infiltration ratio had significantly better survival compared to those with a low tumour/stroma infiltration ratio (p=0.023 & <0.001 respectively). Conversely high intratumoral T-regulatory FOXP3+ positive lymphocyte infiltration rates were associated with a particularly poor prognosis independent of surgical stage (p<0.001). Conclusions: Microlocalization of infiltrating T-lymphocytes, in particular Treg cells, is a powerful predictor of outcome for surgically resected NSCLC and compares favourably with recently published prognostic genomic approaches. Assessment of inflammatory cell infiltrates may help determine which patients should receive adjuvant chemotherapy and, in the future, in predicting benefit from novel adjuvant vaccine/immunotherapies.

No significant financial relationships to disclose.

Report of the equine herpesvirus-1 Havermeyer Workshop, San Gimignano, Tuscany, June 2004

Amongst the infectious diseases that threaten equine health, herpesviral infections remain a world wide cause of serious morbidity and mortality. Equine herpesvirus-1 infection is the most important pathogen, causing an array of disorders including epidemic respiratory disease abortion, neonatal foal death, myeloencephalopathy and chorioretinopathy. Despite intense scientific investigation, extensive use of vaccination, and established codes of practice for control of disease outbreaks, infection and disease remain common. While equine herpesvirus-1 infection remains a daunting challenge for immunoprophylaxis, many critical advances in equine immunology have resulted in studies of this virus, particularly related to MHC-restricted cytotoxicity in the horse. A workshop was convened in San Gimignano, Tuscany, Italy in June 2004, to bring together clinical and basic researchers in the field of equine herpesvirus-1 study to discuss the latest advances and future prospects for improving our understanding of these diseases, and equine immunity to herpesviral infection. This report highlights the new information that was the focus of this workshop, and is intended to summarize this material and identify the critical questions in the field.

[Type IV secretion system and their effectors: an update]

Subversion of eukaryotic hosts by bacterial pathogens requires specialized macromolecules secretion systems delivering virulence factors either into the environment or directly into host cells. Transport of molecules across bacterial and eukaryotic membranes is a process requiring multi-component machineries called secretion systems. This review focuses on the Type IV secretion system. This complex is required for genetic exchange (DNA transport) and secretion of effectors (proteins, macromolecules, DNA-proteins complex) into target cells. They transport a wide variety of substrates including large DNA/protein complexes, multi protein toxins, or individual proteins. We describe recent advances on the structure and the function of this secretion system, their effectors and their effects on the functions of eukaryotic cell.

Effects of diets fed to dairy cows before and after calving on their plasma progesterone profiles after calving

Four weeks before their predicted mean second lactation calving date, 60 spring-calving Holstein-Friesian cows were blocked into groups of six on the basis of their predicted calving date and body condition score, and allocated at random to one of six dietary treatments in a factorial design: ad libitum grass silage, ad libitum grass silage plus barley straw or ad libitum grass silage plus 3 kg of concentrates, was offered for four weeks before the expected calving date, and after calving they were offered either 4 kg or 8 kg of concentrates plus ad libitum grass silage for eight weeks. On average, the first luteal activity occurred in all the groups at 29 days after calving. Seventeen of the cows had an atypical first plasma progesterone profile; 12 were anovulatory, three had prolonged luteal phases and two became anovulatory after having been cyclic. The cows offered grass silage only before calving had a significantly shorter mean (se) interval between calving and second luteal activity (44.9 [2.1] days), than the cows offered grass silage and straw (53.5 [1.9] days) or grass silage and concentrates (51.5 [3.2] days) (P<0.05). After calving none of the 28 cows offered grass silage and 4 kg of concentrates started cycling before day 21, whereas five of the 30 cows offered grass silage and 8 kg of concentrates cycled before day 21 (P<0.05).

[Strategies for bacterial virulence genes identification]

One of the recent preoccupations of medical microbiology has been to characterise the mechanisms of virulence of bacterial pathogens at the molecular level. One hundred years after Koch, Stanley Falkow proposed a new, molecular version of Koch's postulates to define avirulence gene: (a) the gene confers a certain phenotype to the studied bacteria, (b) inactivation of the gene abolishes the phenotype, (c)reintroduction of the gene restores the wild type to the mutant. Although this strategy, based upon mutagenesis and the use of experimental models, allows the identification of many genes, it is not comprehensive. Other methods can be used to complete the identification of virulence factors such as differential expression, either at the level of transcription (transcriptome) or at the level of protein expression (proteome). All these techniques are now supported by the data from complete genome sequencing projects. The pool of information obtained from these approaches allows the definition of the 'virulome', which is the assembly of factors a pathogen requires for virulence. Understanding the virulome will open the way to the development of new strategies for vaccination or the development of new generation of antimicrobials.

Influence of nutrition on the effectiveness of superovulation programmes in ewes: effect on oocyte quality and post-fertilization development

Two experiments were carried out to study the effect of nutrition on embryo development in two periods in superovulated ewes (Expt 1) and on oocyte developmental capacity during the late follicular phase (Expt 2). In Expt 1, a lower superovulation response in terms of animals ovulating (P < 0.05), ovulation rate per ewe ovulating (P = 0.1) and number of good quality embryos per animal treated (P < 0.07) was noted in ewes fed an ad libitum diet compared with ewes offered control (1.5 times the daily maintenance energy requirements, 1.5 x M) or low energy (0.5 x M) diets. Nutrition also modified the morphological and functional quality of the oocytes and embryos recovered. Thus, 92% of day 4 embryos recovered from ewes offered the control diet were classified as good embryos, compared with 70 and 82% of those recovered from ewes offered the ad libitum and low diets, respectively (P < 0.05). Ewes offered the ad libitum diet had a greater percentage of poorly developed embryos compared with ewes offered the control or low diets (P < 0.05). Ewes fed the low diet tended to have more non-fertilized oocytes than ewes offered the control diet (P = 0.09). Diet of recipient ewes to which good quality embryos were transferred on day 4 did not affect embryo quality, when assessed 12 days later (day 16 of pregnancy). However, recipient diet affected prostaglandin F(2alpha) (PGF(2alpha)) production in vitro, and uterine tissue that originated from recipient ewes on the low diet secreted more PGF(2alpha) relative to uterine tissue that originated from recipients on the control diet (P < 0.05). In Expt 2, fewer total (P < 0.05) and good quality (P < 0.01) oocytes and a lower percentage of good quality oocytes (P < 0.01) were obtained from superovulated ewes offered the ad libitum diet compared with ewes offered the low diet. In addition, cleavage rate tended to be higher (51 versus 35%, P = 0.09) in ewes offered the low diet compared with ewes offered the ad libitum diet. In conclusion, changes in diet can affect the quality of the oocyte and embryo in superovulated sheep. A lower superovulation response and a decrease in the quality of oocytes and embryos indicate that ad libitum diets are highly detrimental for superovulatory programmes when compared with low and control diets. In addition, the results from the present study indicate that a low energy diet during early embryo development increased the uterine production in vitro of PGF(2alpha) which could lead to a poor uterine environment thereby compromising the development of the embryo.

Influence of nutrition on the effectiveness of superovulation programmes in ewes: effect on oocyte quality and post-fertilization development

Two experiments were carried out to study the effect of nutrition on embryo development in two periods in superovulated ewes (Expt 1) and on oocyte developmental capacity during the late follicular phase (Expt 2). In Expt 1, a lower superovulation response in terms of animals ovulating (P < 0.05), ovulation rate per ewe ovulating (P = 0.1) and number of good quality embryos per animal treated (P < 0.07) was noted in ewes fed an ad libitum diet compared with ewes offered control (1.5 times the daily maintenance energy requirements, 1.5 x M) or low energy (0.5 x M) diets. Nutrition also modified the morphological and functional quality of the oocytes and embryos recovered. Thus, 92% of day 4 embryos recovered from ewes offered the control diet were classified as good embryos, compared with 70 and 82% of those recovered from ewes offered the ad libitum and low diets, respectively (P < 0.05). Ewes offered the ad libitum diet had a greater percentage of poorly developed embryos compared with ewes offered the control or low diets (P < 0.05). Ewes fed the low diet tended to have more non-fertilized oocytes than ewes offered the control diet (P = 0.09). Diet of recipient ewes to which good quality embryos were transferred on day 4 did not affect embryo quality, when assessed 12 days later (day 16 of pregnancy). However, recipient diet affected prostaglandin F(2alpha) (PGF(2alpha)) production in vitro, and uterine tissue that originated from recipient ewes on the low diet secreted more PGF(2alpha) relative to uterine tissue that originated from recipients on the control diet (P < 0.05). In Expt 2, fewer total (P < 0.05) and good quality (P < 0.01) oocytes and a lower percentage of good quality oocytes (P < 0.01) were obtained from superovulated ewes offered the ad libitum diet compared with ewes offered the low diet. In addition, cleavage rate tended to be higher (51 versus 35%, P = 0.09) in ewes offered the low diet compared with ewes offered the ad libitum diet. In conclusion, changes in diet can affect the quality of the oocyte and embryo in superovulated sheep. A lower superovulation response and a decrease in the quality of oocytes and embryos indicate that ad libitum diets are highly detrimental for superovulatory programmes when compared with low and control diets. In addition, the results from the present study indicate that a low energy diet during early embryo development increased the uterine production in vitro of PGF(2alpha) which could lead to a poor uterine environment thereby compromising the development of the embryo.

Effects of calcium salts of fatty acids and calcium salt of methionine hydroxy analogue on plasma prostaglandin F2alpha metabolite and milk fatty acid profiles in late lactation Holstein-Friesian cows

Effects of a dietary lipid supplement containing calcium salts of fatty acids and methionine hydroxy analogue on plasma prostaglandin F2alpha (PGF2alpha) metabolite (PGFM) and milk fatty acid profiles were examined in 40 late lactation, nonpregnant, Holstein-Friesian cows for a period of 70 days. Effects on milk production, milk composition, and blood metabolites were also examined. Cows were paired on the basis of lactation number (first lactation, n = 8; second lactation, n = 32) and randomly assigned from within pairs to one of two dietary treatments: unsupplemented control (C) or 400 g per cow per day of the lipid supplement (S). Cows receiving the supplement had higher (P < 0.05) total milk production, total fat production (kg), and total lactose production (kg). Plasma cholesterol was significantly higher (P < 0.01) after 30 days of treatment in cows receiving the supplement. Cows receiving the supplement had lower (P < 0.01) concentrations of short chain milk fatty acids (C4:0 to C14:1) and higher concentrations of long chain fatty acids (C18:1 and C18:2; P < 0.01) than control animals. Oxytocin-induced prostaglandin release on Day 16 postovulation was increased (P < 0.01) in cows receiving the supplement. In conclusion, supplementation with calcium salts of fatty acids and methionine hydroxy analogue significantly increased milk yield and plasma PGFM.

Effect of nutrition on endocrine parameters, ovarian physiology, and oocyte and embryo development

Reproductive efficiency in high yielding dairy cows has decreased over the past 50 years, despite significant gains in genetic selection for increased milk output. One possible reason for this decline has been a change in the nutritional intake to meet the increased energy and protein demands for higher milk production. Excess energy intake in sheep will lead to significant reductions in progesterone concentrations; the effects in cattle are not so clear. Nutrition, unless radically changed, will have little effect on gonadotropin concentrations in ruminants, and this is in contrast to the situation for pigs and for primates, where very short-term nutritional changes manifest themselves in altered gonadotropin secretion. Cattle with reduced energy intake have smaller dominant follicles and more three-wave cycles, compared with animals on higher feed intakes. One of the main areas where nutrition influences reproductive efficiency is at the level of embryo production. Several studies indicate that excess energy intake reduces the response to superovulation and also decrease the yield of embryos and alters expression of some gene constructs within the developing embryo. The mechanism of this effect is not clear but indications are that the quality of the oocytes may be compromised. Indeed recent data indicate that nutritional changes around the time of mating may have detrimental effects on the establishment of pregnancy in heifers. Thus, nutritional balancing is critical for high-yielding dairy cows, in particular. The challenge remains to modify nutritional and management strategies in such cows to maintain the levels of production made possible by genetic selection and still maintain an acceptable level of fertility.

Effect of diet quantity and urea supplementation on oocyte and embryo quality in sheep

The objective was to investigate the effects of dietary energy and urea supplementation on oocyte and embryo quality in sheep using in vivo and in vitro experimental models. Sixty-three ewes were fed grass meal at 0.5 or 2.0 times maintenance energy requirements (MER). The diet was supplemented with feed grade urea (U) for half of the ewes on each energy treatment. Ewes were stimulated with 1000 IU eCG and either slaughtered on the day of pessary withdrawal, for in vitro embryo production, or mated and slaughtered on Day 5 for embryo recovery. Urea decreased cleavage rate (48.3 vs 39.7%) and consequently blastocyst rate (41.6 vs 36.8%) but the differences were not significant. Oocytes from animals on 2.0 MER had a lower cleavage rate (54.9 vs 36.0%) and blastocyst yield (49.3 vs 31.4%) than those on 0.5 MER. However, there was an interaction between urea and energy for cleavage (P = 0.04) and blastocyst yield (P = 0.03) indicating a variable response to urea in the presence of high energy. This was manifested by a decrease in cleavage rate in the presence of urea and high energy (22%, 8 of 36), and a reduction in blastocyst development (19%, 7 of 36). When blastocyst development rate was expressed as a proportion of cleaved oocytes there was no difference between groups; in addition, there was no difference between groups in terms of blastocyst hatching rate (overall mean 66.1%) or blastocyst cell number on Day 8 (overall mean +/- SEM, 138.4 +/- 9.0, n=61). The effect of urea on cleavage rate in vivo was more severe. Urea supplementation reduced (P<0.001) the cleavage rate (93 vs 62%). Despite this, the yield of blastocysts was unaffected. Oocytes from ewes on 0.5 MER exhibited a lower (P<0.05) cleavage rate than those on 2.0 MER (66 vs 87%). This effect was also apparent at the blastocyst stage (40.0 vs 50.9%), although the difference was no longer significant. There were no differences in hatching rate (overall mean 70.7%) or blastocyst cell numbers (overall mean +/- SEM, 166.3 +/- 15.6, n=40). Collectively, these results suggest that both high dietary energy and urea content influence subsequent embryo development in vitro, and the deleterious effects of urea are likely influenced by concomitant energy intake.

Brucellosis: a worldwide zoonosis

Brucella is one of the world's major zoonotic pathogens, and is responsible for enormous economic losses as well as considerable human morbidity in endemic areas. Control of brucellosis requires practical solutions that can be easily applied to the field. Rapid DNA-based diagnostic tests for both humans and livestock have now proved themselves on an experimental level. Data on the virulence of Brucella suggest common mechanisms shared with plant pathogens and endosymbionts of the alpha-proteobacteria. Understanding virulence will have practical repercussions in the realms of vaccine development and, perhaps, development of new antibiotics. The first complete Brucella genome sequence will be released soon, and this will help greatly in our understanding of the biology and evolution of this pathogen.

Epithelial calcium transporter expression in human duodenum

Calcium absorption in intestine and kidney involves transport through the apical membrane, cytoplasm, and basolateral membrane of the epithelial cells. Apical membrane calcium influx channels have recently been described in rabbit (epithelial calcium channel, ECaC) and rat (calcium transport protein, CaT1). We amplified from human duodenum a 446-base partial cDNA probe (ECAC2) having a predicted amino acid similarity of 97% to rat CaT1. Duodenum, but not ileum, colon, or kidney, expressed a 3-kb transcript. A larger transcript was also found in placenta and pancreas, and a different, faint transcript was found in brain. In duodenal biopsies from 20 normal volunteers, expression varied considerably but was not significantly correlated with vitamin D metabolites. This signal correlated with calbindin-D(9k) (r = 0.48, P < 0.05) and more strongly with the plasma membrane calcium ATPase PMCA1 (r = 0.83, P < 0.001). These data show that although individual variations in calcium channel transcripts are not vitamin D dependent, expression of genes governing apical entry and basolateral extrusion are tightly linked. This may account for some of the unexplained variability in calcium absorption.

Genetic merit for milk production and reproductive success in dairy cows

The effect of genetic merit for milk production traits - fat, protein and milk yield - in dairy cows on milk production, body condition, blood metabolites, reproductive hormones, feed intake and reproductive performance was studied over a period of 2 years. Cows were grouped into two categories, based on calculated pedigree indices using multiple-trait across country evaluation (MACE). Cows of high genetic merit (HGM, n = 48 in year 1 and n = 46 in year 2) had a mean predicted difference +/- standard deviation for milk production of 475 +/- 76kg. The cows of medium genetic merit (MGM, n = 48 in both years) had a mean predicted difference for milk production of 140 +/- 68kg. The cows calved between January and April, and were offered grass silage ad libitum plus 9kg concentrates per cow per day, irrespective genetic merit, from calving to turnout in March, when they were subjected to one of three grazing systems. Cows were available for rebreeding from late April until late July of each year.High genetic merit cows had higher milk production, incurred greater body condition loss between calving and first service and had lower plasma glucose and insulin-like growth factor-1 (IGF-1) concentrations than medium genetic merit cows. Furthermore, HGM cows had lower first and second service and overall conception rates, and required more services per conception than the MGM cows. Cows that did not conceive to first service were retrospectively compared to those that conceived to first service within each genetic merit group. There were no significant differences between the HGM cows that did not conceive to first service and those that conceived to this service in terms of milk production, body condition score change between calving and first service, feed intake at first service, or in plasma concentrations of glucose, non-esterified fatty acids (NEFA) or IGF-1. Medium genetic merit cows that did not conceive to first service lost more body condition between calving and first service than did those that conceived to this service. In the present study, HGM cows had higher milk production and reduced reproductive performance in comparison with MGM cows. However, reproductive performance was not associated with milk production, feed intake or plasma concentrations of glucose, NEFA or IGF-1 between calving and first service, since there were no significant differences in these variates between high or medium genetic merit cows that did not conceive to first service and those that conceived to this service. Therefore, these variates are unlikely to be useful predictors of reproductive performance, under the conditions of the present study.

Aromatic compound-dependent Brucella suis is attenuated in both cultured cells and mouse models

The aroC gene of the facultative intracellular pathogen Brucella suis was cloned and sequenced. The cloned aroC gene complements Escherichia coli and Salmonella enterica serovar Typhimurium aroC mutants. A B. suis aroC mutant was found to be unable to grow in a defined medium without aromatic compounds. The mutant was highly attenuated in tissue culture (THP1 macrophages and HeLa cells) and murine virulence models.

Quantitative changes in collagen levels following 830-nm diode laser welding

BACKGROUND AND OBJECTIVE

The actual mechanism by which laser irradiation welds tissue is presently unknown; however, collagen is a major constituent of tissue welded by laser irradiation.

STUDY DESIGN/MATERIALS AND METHODS

Collagen was extracted from the abdominal aorta of Wistar rats by acetic acid extraction and repeated pepsin digestion after tissue welding (254 W/cm2) by using an 830-nm diode laser. The collagen levels were determined by using the Sircol Collagen Assay (Biocolor, Northern Ireland).

RESULTS

Compared with untreated aorta, the collagen content of the treated vessel was obvious decreased (P < 0.001) immediately after laser irradiation. Levels then increased by day 3, with a peak at day 10 (P < 0.002). The collagen content returned to normal levels on day 30 and remained at this level throughout the rest of the experimental period.

CONCLUSION

These results suggest that a proportion of the collagen molecules in the vessel are denatured by the heat of the laser. Collagen synthesis is stimulated during the healing process after laser welding with the parameters used in the present study.

Effect of nutrition and superovulation on oocyte morphology, follicular fluid composition and systemic hormone concentrations in ewes

The objective was to determine the effect of dietary intake on follicle and oocyte morphology in unstimulated and superovulated ewes. Fifty-four ewes were fed grass meal at 0.5, 1.0 or 2.0 times maintenance energy requirements (M) for 32 days. Oestrous cycles were synchronized using progestagen pessaries and either unstimulated or superovulated with 200 mg pig FSH. The ewes were killed and ovaries were collected either 36 or 12 h before the anticipated LH surge. Serum progesterone concentrations in ewes on day 10 after withdrawal of the pessary were lower in ewes fed 2.0M than in ewes fed 0.5M or 1.0M (P < 0.05). LH pulse frequency tended to be higher in ewes fed 2M than 1M (1.0 +/- 0.3 versus 0.3 +/- 0.2 pulses per 8 h) on day 6 after removal of the pessary but the effect was not significant. In unstimulated ewes, more follicles (>/= 3 mm) were observed when the animals were killed in ewes fed 2.0M (3.5 +/- 0.3) than in ewes fed 0.5M (2.4 +/- 0.3) or 1.0M (2.4 +/- 0.5; P < 0. 05). Fewer follicles were observed in superovulated ewes on 0.5M (7. 5 +/- 1.2) than in ewes on 1.0M (12.0 +/- 0.5) or 2.0M (12.3 +/- 1. 4; P < 0.05). Follicular fluid progesterone concentrations were higher in ewes fed 0.5M compared with those fed 1M or 2M (P < 0.05). Insulin-like growth factor (IGF)-I concentrations were higher in follicular fluid from ewes on 1M compared with either those on 0.5M or 2M (P < 0.05), whereas IGF-II concentrations were lower in follicular fluid from ewes on 2M compared with those on 1M or 0.5M (P < 0.05). Superovulation increased follicular fluid progesterone, oestradiol, IGF-I and IGF-II concentrations (P < 0.01). Concentrations of the 34, 22 and 20 kDa IGF binding proteins were lower in follicles from superovulated ewes compared with unstimulated ewes (P < 0.05). Oocytes from superovulated ewes showed abnormalities such as premature activation of cumulus expansion and vacuolation of the nucleolus and increased frequency of detachment of interchromatin-like granules from the nucleolar remnant. Collectively, these results indicate that both high and low dietary intakes can alter systemic and follicular fluid hormone concentrations. Relative to dietary effects, the effects of superovulation were greater and involved substantial increases in follicular fluid hormone concentrations and abnormal oocyte morphology.

Identification of Brucella suis genes affecting intracellular survival in an in vitro human macrophage infection model by signature-tagged transposon mutagenesis

Bacteria of the genus Brucella are facultative intracellular pathogens which have developed the capacity to survive and multiply in professional and nonprofessional phagocytes. The genetic basis of this aspect of Brucella virulence is still poorly understood. To identify new virulence factors, we have adapted signature-tagged transposon mutagenesis, which has been used essentially in animal models, to an in vitro human macrophage infection model. A library of 1,152 Brucella suis 1330 tagged mini-Tn5 Km2 mutants, in 12 pools, was screened for intracellular survival and multiplication in vitamin D(3)-differentiated THP1 cells. Eighteen mutants were identified, and their attenuation was confirmed in THP1 macrophages and HeLa cells. For each avirulent mutant, a genomic fragment containing the transposon was cloned. The genomic DNA sequence flanking the transposon allowed us to assign functions to all of the inactivated genes. Transposon integration had occurred in 14 different genes, some of which were known virulence genes involved in intracellular survival or biosynthesis of smooth lipopolysaccharide (the virB operon and manB), thus validating the model. Other genes identified encoded factors involved in the regulation of gene expression and enzymes involved in biosynthetic or metabolic pathways. Possible roles in the virulence of Brucella for the different factors identified are discussed.

Effect of nutrition and superovulation on oocyte morphology, follicular fluid composition and systemic hormone concentrations in ewes

The objective was to determine the effect of dietary intake on follicle and oocyte morphology in unstimulated and superovulated ewes. Fifty-four ewes were fed grass meal at 0.5, 1.0 or 2.0 times maintenance energy requirements (M) for 32 days. Oestrous cycles were synchronized using progestagen pessaries and either unstimulated or superovulated with 200 mg pig FSH. The ewes were killed and ovaries were collected either 36 or 12 h before the anticipated LH surge. Serum progesterone concentrations in ewes on day 10 after withdrawal of the pessary were lower in ewes fed 2.0M than in ewes fed 0.5M or 1.0M (P < 0.05). LH pulse frequency tended to be higher in ewes fed 2M than 1M (1.0 +/- 0.3 versus 0.3 +/- 0.2 pulses per 8 h) on day 6 after removal of the pessary but the effect was not significant. In unstimulated ewes, more follicles (>/= 3 mm) were observed when the animals were killed in ewes fed 2.0M (3.5 +/- 0.3) than in ewes fed 0.5M (2.4 +/- 0.3) or 1.0M (2.4 +/- 0.5; P < 0. 05). Fewer follicles were observed in superovulated ewes on 0.5M (7. 5 +/- 1.2) than in ewes on 1.0M (12.0 +/- 0.5) or 2.0M (12.3 +/- 1. 4; P < 0.05). Follicular fluid progesterone concentrations were higher in ewes fed 0.5M compared with those fed 1M or 2M (P < 0.05). Insulin-like growth factor (IGF)-I concentrations were higher in follicular fluid from ewes on 1M compared with either those on 0.5M or 2M (P < 0.05), whereas IGF-II concentrations were lower in follicular fluid from ewes on 2M compared with those on 1M or 0.5M (P < 0.05). Superovulation increased follicular fluid progesterone, oestradiol, IGF-I and IGF-II concentrations (P < 0.01). Concentrations of the 34, 22 and 20 kDa IGF binding proteins were lower in follicles from superovulated ewes compared with unstimulated ewes (P < 0.05). Oocytes from superovulated ewes showed abnormalities such as premature activation of cumulus expansion and vacuolation of the nucleolus and increased frequency of detachment of interchromatin-like granules from the nucleolar remnant. Collectively, these results indicate that both high and low dietary intakes can alter systemic and follicular fluid hormone concentrations. Relative to dietary effects, the effects of superovulation were greater and involved substantial increases in follicular fluid hormone concentrations and abnormal oocyte morphology.

Effect of genetic merit, milk yield, body condition and lactation number on in vitro oocyte development in dairy cows

The effects of milk yield, body condition score (BCS) and lactation number on the number of oocytes recovered and blastocysts formed were studied following in vitro maturation, fertilization and culture of bovine oocytes collected from 48 high and 46 medium genetic merit dairy cows in their first and third lactation. The cows were slaughtered between 125 and 229 d post partum. Ovaries were recovered, and 2- to 10-mm follicles were aspirated. Cleavage rate and number of blastocysts were determined at 44 h and 7 d after insemination, respectively. Oocytes from high genetic merit cows formed fewer blastocysts and had lower cleavage and blastocyst formation rates than those from medium genetic merit cows (0.36 +/- 0.19, 70.4 and 6.8% vs 0.85 +/- 0.22, 77.4 and 11.4%, respectively). The effect of milk production was tested by grouping cows in their third lactation into high and low groups. There was no difference in number of oocytes recovered and subsequent development into blastocysts between the cows in the high milk production group (4559 to 5114 kg, n = 20) and cows in the low yield (3162 to 3972 kg, n = 20) group (6.9 +/- 1.34 vs 8.9 +/- 1.32, respectively). The effect of BCS was tested by grouping cows in their first or third lactation into high and low groups. Cleavage and blastocyst formation rates were greater for oocytes from cows with a high BCS (3.3 to 4.0, n = 20) than a low BCS (1.5 to 2.5, n = 20) (75.7 vs 61.9% and 9.9 vs 3.0%, respectively). Cows in the first lactation yielded fewer oocytes (5.7 +/- 1.24) than cows in the third lactation (7.8 +/- 0.79). Thus, the quality of oocytes probably contributes to reduced fertility, often evident in high genetic merit dairy cows.

Effects of superovulated heifer diet type and quantity on relative mRNA abundances and pyruvate metabolism in recovered embryos

This study investigated the effects of quantity and type of diet fed to superovulated donor heifers on molecular and metabolic indices of embryonic development. These effects included the relative abundances of mRNAs for the alpha 1 subunit of Na/K-ATPase and the antioxidant enzyme Cu/Zn-SOD, as well as pyruvate utilization in bovine morulae and blastocysts developed in vivo. Heifers were fed a daily ration of either grass silage and a citrus-beet pulp-based concentrate or grass silage and a barley-based concentrate for 116 days, both at 3 kg per day or ad libitum. In embryos derived from heifers fed the pulp-based diets, the relative abundances of the transcripts were not affected by either day of collection or quantity of diet. In embryos derived from heifers fed the barley-based diets, the relative abundances of the Na/K-ATPase transcripts were also not changed by these main effects, while the relative abundances of the Cu/Zn-SOD transcripts were affected by day of collection and by the quantity of diet. Pyruvate metabolism was affected by day of collection, and was significantly increased in day 8 embryos compared with day 7 and day 6 embryos. Diet quantity did not affect pyruvate utilization, whereas diet type did increase pyruvate metabolism in the barley group when compared with the pulp group. The results of this study show for the first time that molecular and metabolic variations may exist in embryos derived in vivo and developed in donor heifers on nutritional regimens differing in type and quantity. Differences in embryos collected on different developmental days may be attributed to varying cell numbers. Alterations in the relative abundances of the Cu/Zn-SOD transcripts and pyruvate metabolism caused by the quantity of diet fed to the donor animal were likely to have been due to alterations in metabolic end products that accumulate in reproductive tract fluids, whereas differences in embryonic metabolism caused by type of diet are related to the composition of the diet. These findings characterize embryos produced in vivo at the molecular level, indicating that the molecular markers used in the present study can differentiate between populations of embryos produced under different nutritional regimens and determine conditions conductive to the production of good quality embryos.

Effects of superovulated heifer diet type and quantity on relative mRNA abundances and pyruvate metabolism in recovered embryos

This study investigated the effects of quantity and type of diet fed to superovulated donor heifers on molecular and metabolic indices of embryonic development. These effects included the relative abundances of mRNAs for the alpha 1 subunit of Na/K-ATPase and the antioxidant enzyme Cu/Zn-SOD, as well as pyruvate utilization in bovine morulae and blastocysts developed in vivo. Heifers were fed a daily ration of either grass silage and a citrus-beet pulp-based concentrate or grass silage and a barley-based concentrate for 116 days, both at 3 kg per day or ad libitum. In embryos derived from heifers fed the pulp-based diets, the relative abundances of the transcripts were not affected by either day of collection or quantity of diet. In embryos derived from heifers fed the barley-based diets, the relative abundances of the Na/K-ATPase transcripts were also not changed by these main effects, while the relative abundances of the Cu/Zn-SOD transcripts were affected by day of collection and by the quantity of diet. Pyruvate metabolism was affected by day of collection, and was significantly increased in day 8 embryos compared with day 7 and day 6 embryos. Diet quantity did not affect pyruvate utilization, whereas diet type did increase pyruvate metabolism in the barley group when compared with the pulp group. The results of this study show for the first time that molecular and metabolic variations may exist in embryos derived in vivo and developed in donor heifers on nutritional regimens differing in type and quantity. Differences in embryos collected on different developmental days may be attributed to varying cell numbers. Alterations in the relative abundances of the Cu/Zn-SOD transcripts and pyruvate metabolism caused by the quantity of diet fed to the donor animal were likely to have been due to alterations in metabolic end products that accumulate in reproductive tract fluids, whereas differences in embryonic metabolism caused by type of diet are related to the composition of the diet. These findings characterize embryos produced in vivo at the molecular level, indicating that the molecular markers used in the present study can differentiate between populations of embryos produced under different nutritional regimens and determine conditions conductive to the production of good quality embryos.

A homologue of the Agrobacterium tumefaciens VirB and Bordetella pertussis Ptl type IV secretion systems is essential for intracellular survival of Brucella suis

Analysis of a TnblaM mutant of Brucella suis 1330, identified as being unable to multiply in Hela cells, allowed us to identify a 11 860 bp region of the B. suis genome encoding a type IV secretion system, homologous to the VirB system of Agrobacterium tumefaciens and the Ptl system of Bordetella pertussis. DNA sequence revealed 12 open reading frames (ORFs) encoding homologues of the 11 VirB proteins present in the pTi plasmid of Agrobacterium with a similar genetic organization, and a twelfth ORF encoding a putative lipoprotein, homologous to a protein involved in mating pair formation during bacterial conjugation and to adhesins used by Pseudomonas species to bind to plant roots. Phylogenetic trees based on the sequences of VirB4 and VirB9 protein homologues suggest that evolution of the systems from DNA transfer towards protein secretion did not stem from a single event but that the protein secretion systems have evolved independently. Four independent mutants in virB5, virB9 or virB10 were highly attenuated in an in vitro infection model with human macrophages. The virulence was restored by complementation with a plasmid containing the full virB region. The virB region appears to be essential for the intracellular survival and multiplication of B. suis.

Investigation into the role of the response regulator NtrC in the metabolism and virulence of Brucella suis

During infection, Brucella species have to adapt to a range of different environments. Environmental sensing in bacteria often involves the concerted action of two-component regulatory systems consisting of sensor and response regulator components. In this study, we identified, cloned and sequenced four independent response regulator gene fragments from Brucella melitensis. One amplified gene fragment showed nearly 90% identity to the response regulator subfamily of NtrC transcriptional activators, and further analysis revealed the presence of an adjacent gene encoding the sensor protein NtrB. The NtrBC two-component regulatory system has been shown to play varying roles in nitrogen metabolism and potentially in virulence in other bacterial species. A B. suis ntrC isogenic mutant was constructed which showed no significant differences in growth rates compared to the wild-type strain when grown at different temperatures in vitro. However, the mutant exhibited a reduction in metabolic activity in the presence of many amino acids. The mutation did not affect survival or multiplication of B. suis in macrophages, but during the initial stages of infection in the murine brucellosis model, the ntrC mutant showed a reduced ability to multiply rapidly in splenic tissue.

Effect of type and quantity of concentrates on superovulation and embryo yield in beef heifers

Embryo yield and quality can be decreased following superovulation of cattle on high levels of concentrates. Concentrate type can alter rumen fermentation patterns and so affect energy availability and thus embryo quality. The objectives of this experiment were to examine the effect of 2 levels and 2 types of concentrate on superovulatory response and embryo quality in beef heifers. Beef heifers received grass silage as a basal diet and barley at 3 kg (n = 20) or ad-libitum (n = 19), or citrus/beet pulp at 3 kg (n = 18) or ad-libitum (n = 19) as the source of concentrate supplement. Silage was available ad-libitum for heifers offered 3 kg but was restricted to 1 kg DM/day for heifers on ad-libitum concentrate intake. Both concentrates contained 14% crude protein. After 100 d, heifers were treated with an intravaginal progesterone releasing device (CIDR) for 7 d, and superovulation was initiated 60 h before CIDR withdrawal. Heifers received pFSH (a total of 265 mg NIH-FSH-P1 equivalent) administered over 8 injections at 12 h intervals with the last 2 injections administered at 12 and 24 h after CIDR withdrawal; they were inseminated at 56 and 72 h after CIDR withdrawal without reference to estrus. Heifers were slaughtered 6, 7 or 8 d after the first insemination, and embryos were flushed from the uterus with PBS and were graded morphologically. Statistical analyses were performed using analysis of variance. There was no interaction between level and type of diet, and thus data for the main effects are presented separately. Final live weights at the end of the experiment and carcass weights for heifers offered ad-libitum concentrate (643.8+/-6.9 kg; 354+/-8 kg, respectively) were higher (P<0.01) than those of heifers offered 3 kg concentrate (613.1+/-7.5 kg; 338.4+/-3.2 kg, respectively) while live weights and carcass weights of heifers offered barley (625.6+/-8.1 and 345.4+/-4.1 kg, respectively) or citrus/beet pulp concentrate (631.4+/-7.0 and 348.0+/-3.1 kg, respectively) were not different (P>0.05). Superovulatory responses (number of corpora lutea at slaughter) was greater (P<0.06) when heifers were offered 3 kg (15.5+/-1.6) than when offered ad-libitum concentrates (12.3+/-1.4). However, the superovulatory response for both citrus/beet pulp (14.4+/-1.5) and barley (13.4+/-1.5) diets were not different (P>0.05). Heifers offered 3 kg concentrates produced greater (P<0.05) numbers of transferable embryos (4.8+/-0.7) compared with heifers fed ad-libitum concentrates (2.8+/-0.4). Heifers offered citrus/beet pulp produced greater (P<0.05) numbers of transferable embryos (4.8+/-0.7) than heifers offered barley (2.9+/-0.5). These data indicate that high concentrate intake has a negative effect on embryo yield and quality and that a barley compared with citrus/beet pulp based concentrate has a negative effect on embryo quality following superovulation in beef heifers.

Effect of immunization against melatonin on prolactin concentrations and the timing of reproductive transitions in ewes

The objective of this experiment was to develop a procedure for immunizing ewes against melatonin that would alter the effects of changing photoperiod on seasonal reproduction and prolactin secretion. Ewes were immunized against human serum albumin (HSA) as controls (n = 9) or a melatonin-human serum albumin conjugate (0.25 mg; n = 10) on December 14th (Day 0) and boosted 9 times. They were maintained on natural photoperiod and then transferred indoors and exposed to long days for 35 d, followed by short days for 146 d, long days for 93 d, and short days for a further 123 d. Antibody titers to melatonin (at a serum dilution of 1:1,250) were significantly higher in immunized ewes (27.3 +/- 6.6%) than controls (0.7 +/- 0.1%; P < 0.001). At the end of the experiment, antibody titers in immunized ewes (at dilution of 1:50) were higher in blood (43.7 +/- 8.2%) than in cerebrospinal fluid (10.8 +/- 3.9%; P < 0.05), and highly correlated (r2 = 0.746). Onset of the breeding season was advanced slightly after the second transfer from long to short days in immunized ewes (April 12 +/- 3 d) compared with controls (April 25 +/- 3 d; P < 0.05). Mean serum prolactin concentrations were lower (P < 0.05) in melatonin-immunized ewes compared with controls on natural photoperiod, after transfer from long to short days, during long days, and after the second transfer from long to short days. In conclusion, despite melatonin-immunization increasing antibody titers in blood and cerebrospinal fluid, and decreasing prolactin concentrations over much of the experiment, minimal effects on the timing of reproductive transitions in the ewes were evident. This discrepancy between the response of the prolactin and reproductive axes to melatonin immunization supports the hypothesis of a dual site of action of melatonin, with melatonin acting in the pituitary gland to mediate the effects of photoperiod on prolactin secretion and in the mediobasal hypothalamus to affect reproductive responses.

Effect of roughage type and concentrate supplementation on follicle numbers and in vitro fertilisation and development of oocytes recovered from beef heifers

Increasing dietary energy tends to decrease the ovulatory response and produce fewer viable embryos following superovulation of beef cattle. Data in sheep indicate that high energy intake can decrease progesterone concentrations (P4), although effects in cattle are not as clear. The objectives were to evaluate the effects of roughage type and concentrate supplementation on P4 concentrations, follicle growth and subsequent oocyte fertilisation and embryo development in vitro. Forty-two beef heifers were allocated to 3 treatment groups: (i) silage ad libitum plus 6 kg concentrates (silage + conc.; n = 14); (ii) silage ad libitum (silage; n = 14) or (iii) hay ad libitum (hay; n = 14) for 40 days. Oestrus was synchronised using a controlled intravaginal progesterone releasing device (CIDR) for 7 days plus prostaglandin F2 alpha (15 mg luprostiol) administered 2 days before CIDR withdrawal. Ovaries were stimulated with 600 i.u. of follicle stimulating hormone (pFSH) administered in 6 equal doses at 12-h intervals, starting 12 days after CIDR withdrawal. Daily blood samples were collected from 3 days after CIDR insertion until CIDR withdrawal, and for another 3 days prior to pFSH, for P4 determination. Oocytes were recovered postmortem 12 h after the last pFSH injection, matured, fertilised and cultured in vitro. There was no overall effect of diet (P > 0.05) on P4 concentrations. The number of follicles grown in heifers on silage + conc (18.8 +/- 3.3), silage (23.5 +/- 3.4) or hay (18.1 +/- 2.6) were not affected by the dietary treatment (P > 0.05). The percentage of oocytes fertilised from heifers on hay (88%) was higher compared to oocytes from heifers on silage (79%; P < 0.05), but was not different (P > 0.05) compared to the proportion of oocytes from heifers on silage + conc. (86%). The percentage of fertilised oocytes that cleaved was higher from heifers on silage (94%; P < 0.01) compared with oocytes from heifers on hay (82%) or silage + conc. (86%). The proportion of embryos that developed to blastocyst was not different (P > 0.05) between groups of oocytes from heifers on silage + conc. (8%), silage (14%) or hay (15%). Heifers on silage produced numerically more blastocysts (silage: 19 from 14 heifers; silage + conc.: 8 from 14 heifers; hay: 12 from 14 heifers). These results suggest that dietary treatment used prior to oocyte recovery did not significantly influence the developmental competence of the oocytes in vitro.

Seasonal variation in long-day stimulation of prolactin secretion in ewes

Whereas ewes initiate reproductive activity in response to a photoperiod signal initiated after the winter solstice of 35 long days (35 LD) followed by short days, the reproductive axis fails to respond to this signal between the autumn equinox and the winter solstice. The aim of experiment 1 was to determine whether the prolactin axis, like the reproductive axis, is unresponsive to a 35 LD photoperiod signal followed by continuous exposure to short days between the autumn equinox and the winter solstice. Whereas the 35 LD signal from September 21 (</= 6 h increase in day length) failed to influence prolactin secretion, all other long-day treatments (> 6 h increase in day length) initiated a rise in prolactin in at least 75% of ewes in each group (p < 0.05). The aim of experiment 2 was to determine whether ewes failed to secrete prolactin during a 35 LD photoperiod from September 21 because they did not recognize a 6-h increase in day length at any time of year as a stimulatory photoperiod signal or because hypothalamic/pituitary regulation of prolactin synthesis or secretion is compromised in September. The results demonstrated that while hypothalamic regulation of prolactin secretion and pituitary stores of prolactin were normal at all times of year examined, the ability of ewes to secrete prolactin in response to a long-day photoperiod signal appears to be dependent on photoperiodic history rather than the time of year of the photoperiodic challenge.

The influence of short-term nutrient changes on follicle growth and embryo production following superovulation in beef heifers

Acute decreases in nutrient intake can improve embryo quality in sheep, although reductions in ovulation rate can also occur. In cattle, short-term nutrient restriction prior to ovulation has been shown to increase subsequent pregnancy rates. Thus, the objective was to determine the effect of a severe reduction in food intake on follicle growth and embryo quantity and quality in heifers superovulated with FSH. Beef heifers (n = 61) were offered a diet of grass silage and concentrates (ratio of 5:1, on a fresh weight basis), which was adjusted to provide a predicted intake of 28.6 Mcal/kg ME/d (H) or 9.6 Mcal/kg ME/d (L). Heifers were synchronized with a progesterone-releasing device for 7 d. They were allocated to oocyte recovery (n = 16/treatment) after 3 (225 IU) or 8 (600 IU) injections of FSH given at 12-h intervals. Oocytes were matured, fertilized and cultured individually in vitro. The remaining heifers (n = 14/treatment) were superovulated using FSH (600 IU), and embryos were recovered 7 d after breeding. The embryos were morphologically graded and subsequently cultured for 24 h before differential staining to determine inner cell mass and trophectoderm cell numbers. Follicle numbers increased following 8 (16.6 +/- 2.0) compared with 3 (6.7 +/- 0.6) injections of FSH (P < 0.0001). Heifers on the L diet had more follicles than those on the H diet (13.5 +/- 2.4 vs 9.6 +/- 1.2; P < 0.06), which was predominantly due to an increase in the number of 7- to 10-mm follicles. However, this effect was only evident after 8 injections of FSH. There was no nutritional effect on cleavage rates in vitro (55.6 +/- 8.1 vs 53.8 +/- 9.0 for H vs L diets, respectively). However, cleavage rates were lower in oocytes collected after 8 than after 3 injections of FSH (31.3 vs 69.2%; P < 0.0001). There was no significant effect of nutrition on ovulation rate after FSH (14.4 +/- 1.9 vs 16.3 +/- 3.0 for H vs L diet, respectively). The number of embryos recovered was not different between heifers on H (10.4 +/- 1.3) and L (11.3 +/- 2.4) diets. Following culture for 24 h, a significantly higher proportion of embryos from heifers on the L diet developed to the blastocyst stage (72.9 vs 41.5%; P < 0.01). Total cell numbers on Day 8 were greater in embryos from heifers on the L diet (98.3 vs 75.4; P < 0.0001); yet the inner cell mass as a percentage of total cells was not different (21 vs 20%). These data indicate that low energy intake prior to and during superovulation resulted in more follicles and in improved embryo quality, as evident from the increased number of blastocysts formed and higher cell numbers.

Effect of timing of oestradiol benzoate injection relative to gonadotropin treatment on superovulatory response, and on embryo yield and quality in beef heifers

Variation in superovulatory responses in cattle may be related to the stage of follicular growth at the time of gonadotropin treatment. Waves of follicle growth are regulated by both follicle-stimulating hormone (FSH) and oestradiol. The objective of experiment 1 was to determine the dynamics of follicle wave emergence and the relationship with FSH and oestradiol concentrations, after treatment of heifers with oestradiol benzoate (ODB) in the presence of an intravaginal progesterone-releasing device (CIDR-B). Experiment 2 examined the superovulatory response, embryo yield and quality following treatment with porcine follicle-stimulating hormone (pFSH) at different times relative to ODB injection. In experiment 1, 28 beef heifers were treated with a CIDR for 9 days and allocated at random to one of four groups to receive either: (I) CIDR only, or 5 mg ODB given as a single intramuscular injection at (II) day 0 (d0); (III) day 1.5 (d1.5); or (IV) day 3 (d3) post CIDR insertion. Ovaries were examined using daily ultrasound and blood samples were collected twice daily for 11 days. In experiment 2, 96 heifers were treated with a CIDR and 5 mg ODB as in experiment 1, and were allocated using a 4 x 3 factorial design plan to a superovulation programme using three doses (400 IU; 600 IU; 800 IU) of pFSH. FSH was given for 4 days at 12-h intervals beginning 6.5 days after CIDR insertion. Heifers received prostaglandin analogue 12 h before CIDR removal and were inseminated (AI) at 48 and 60 h post CIDR withdrawal and embryos were recovered 7 days after AI. In experiment 1, the interval from CIDR insertion to follicle wave emergence (FWE) was longer (P < 0.05) in heifers treated with ODB at d1.5 (5.4 +/- 0.4 days) and d3 (5.1 +/- 0.6 days) compared to heifers treated with CIDR only (2.4 +/- 0.4 days). On the basis of time to proposed injection of pFSH heifers would have had follicle emergence 4.4, 2.3, 1.5 and 1.4 days prior to pFSH for groups I, II, III and IV, respectively. In experiment 2, heifers treated with ODB at d1.5 had a higher (P < 0.05) superovulatory response (18.2 +/- 1.7) than heifers treated at d3 (12.8 +/- 1.7), but superovulatory response in both groups did not differ (P > 0.05) from heifers treated at d0 (14.4 +/- 2.0) or with CIDR only (15.0 +/- 1.8). There were fewer (P < 0.05) freezable-grade embryos recovered from heifers treated with ODB at d0 (1.5 +/- 0.7) and d3 (2.1 +/- 0.5) compared to heifers treated at d1.5 (3.0 +/- 0.6) or in heifers treated with CIDR only (3.4 +/- 0.7). Increasing the dose of pFSH caused a linear increase in the superovulatory response (11.7 +/- 1.0, 15.8 +/- 1.4 and 18.0 +/- 1.9) and in the number of embryos recovered (5.8 +/- 0.9, 7.0 +/- 0.8 and 9.1 +/- 1.0) for 400 IU, 600 IU and 800 IU, respectively. In conclusion, heifers treated with ODB had wide variation in time to follicle wave emergence and there was not a consistent beneficial effect of pretreatment with ODB on embryo yield and quality following superovulation.

Identification, cloning and initial characterisation of FeuPQ in Brucella suis: a new sub-family of two-component regulatory systems

To cause disease, Brucella species have to adapt to a range of different environments. Environmental sensing and adaptive responses in bacteria often involve the concerted action of a two-component regulatory system, consisting of sensor and response regulator components. Amplification and sequence analysis of response regulators from Brucella species identified a response regulator sequence with 96% similarity to Rhizobium leguminosarum FeuP. In R. leguminosarum, the FeuPQ two-component system is involved in the regulation of iron uptake. A Brucella suis feuP isogenic mutant was constructed but was not attenuated in the murine brucellosis model. The survival and multiplication of the mutant in macrophages was also unaffected. The FeuPQ regulon represents a newly characterised sub-family of response regulators.

Differences in chromosome number and genome rearrangements in the genus Brucella

We have studied the genomic structure and constructed the SpeI, PacI and I-CeuI restriction maps of the four biovars of the pathogenic bacterium Brucella suis. B. suis biovar 1 has two chromosomes of 2.1 Mb and 1.15 Mb, similar to those of the other Brucella species: B. melitensis, B. abortus, B. ovis and B. neotomae. Two chromosomes were also observed in the genome of B. suis biovars 2 and 4, but with sizes of 1.85 Mb and 1.35 Mb, whereas only one chromosome with a size of 3.1 Mb was found in B. suis biovar 3. We show that the differences in chromosome size and number can be explained by rearrangements at chromosomal regions containing the three rrn genes. The location and orientation of these genes confirmed that these rearrangements are due to homologous recombination at the rrn loci. This observation allows us to propose a scheme for the evolution of the genus Brucella in which the two chromosome-containing strains can emerge from an hypothetical ancestor with a single chromosome, which is probably similar to that of B. suis biovar 3. As the genus Brucella is certainly monospecific, this is the first time that differences in chromosome number have been observed in strains of the same bacterial species.

Genome structure and phylogeny in the genus Brucella

PacI and SpeI restriction maps were obtained for the two chromosomes of each of the six species of the genus Brucella: B. melitensis, B. abortus, B. suis, B. canis, B. ovis, and B. neotomae. Three complementary techniques were used: hybridization with the two replicons as probes, cross-hybridization of restriction fragments, and a new mapping method. For each type strain, a unique I-SceI site was introduced in each of the two replicons, and the location of SpeI sites was determined by linearization at the unique site, partial digestion, and end labeling of the fragments. The restriction and genetic maps of the six species were highly conserved. However, numerous small insertions or deletions, ranging from 1 to 34 kb, were observed by comparison with the map of the reference strain of the genus, B. melitensis 16M. A 21-kb Spel fragment specific to B. ovis was found in the small chromosome of this species. A 640-kb inversion was demonstrated in the B. abortus small chromosome. All of these data allowed the construction of a phylogenetic tree, which reflects the traditional phenetic classification of the genus.

Structural and antigenic identification of the ORF12 protein (alpha TIF) of equine herpesvirus 1

The equine herpesvirus 1 (EHV-1) homolog of the herpes simplex virus type 1 (HSV-1) tegument phosphoprotein, alpha TIF (Vmw65; VP16), was identified previously as the product of open reading frame 12 (ORF12) and shown to transactivate immediate early (IE) gene promoters. However, a specific virion protein corresponding to the ORF12 product has not been identified definitively. In the present study the ORF12 protein, designated ETIF, was identified as a 60-kDa virion component on the basis of protein fingerprint analyses in which the limited proteolysis profiles of the major 60-kDa in vitro transcription/ translation product of an ORF12 expression vector (pT7-12) were compared to those of purified virion proteins of similar size. ETIF was localized to the viral tegument in Western blot assays of EHV-1 virions and subvirion fractions using polyclonal antiserum and monoclonal antibodies generated against a glutathione-S-transferase-ETIF fusion protein. Northern and Western blot analyses of EHV-1-infected cell lysates prepared under various metabolic blocks indicated that ORF12 is expressed as a late gene, and cross reaction of polyclonal anti-GST-ETIF with a 63.5-kDa HSV-1 protein species suggested that ETIF and HSV-1 alpha TIF are antigenically related. Last, DNA band shift assays used to assess ETIF-specific complex formation indicated that ETIF participates in an infected cell protein complex with the EHV-1 IE promoter TAATGARAT motif.

Influence of previous photoperiodic exposure on the reproductive response to a specific photoperiod signal in ewes

Two experiments were carried out to determine whether the reproductive response of ewes to a specific photoperiodic signal depends on the time of year that the signal is given, and, if so, whether this dependence can be attributed to the photoperiodic history of the ewes. The aim of experiment 1 was to expand upon previous findings that the reproductive response to a specific photoperiodic challenge in ewes previously maintained on natural photoperiod varies with time of year. Ewes were transferred at one of three times of year from natural photoperiod to photochambers and were immediately exposed to 35 long days (18L:6D) followed by continuous exposure to short days (8.5L: 15.5D); this treatment is referred to as LD-->SD. The three times of year when long days started corresponded to the beginning of the breeding season, the mid-breeding season, and early anestrus (September 21, December 21, March 21, respectively). In ewes exposed to LD-->SD beginning in September, the breeding season and subsequent anestrous season was not altered. In ewes exposed to LD-->SD beginning in December, the transition to anestrus was advanced (p < 0.05) relative to that in controls maintained in simulated natural photoperiod. Subsequently, half of these ewes resumed reproductive activity within 180 days; this occurred 131 +/- 8 days after transfer to short days. In contrast, all ewes exposed to LD-->SD beginning in March resumed reproductive activity; this began 100 +/- 3 days after transfer to short days (p < 0.05 versus December group). The purpose of experiment 2 was to assess the extent to which the difference in response to a photoperiodic challenge can be attributed to photoperiodic history. Ewes were maintained on short days from the winter solstice interrupted with 35 long days from March 21, June 21, September 21, or December 21. The majority of ewes exhibited an onset of reproductive activity after exposure to LD-->SD at the different times of year, and there was no group difference in latency to onset of reproductive activity. The duration of reproductive activity, however, was longer (p < 0.05) in ewes exposed to LD-->SD beginning in June than in the other groups. Thus we conclude that the seasonal difference in the ability of the photoperiodic challenge of long followed by short days to induce reproductive activity in ewes previously maintained outdoors can be attributed, in large measure, to photoperiodic history. Other factors, such as phase of the endogenous rhythm, however, may influence the duration of reproductive activity resulting from this photoperiodic challenge.

Effect of immunization of rams against bovine inhibin alpha 1-26 on semen characteristics, scrotal size, FSH, LH and testosterone concentrations

The effects of inhibin immunization on inhibin antibody titres, semen characteristics, scrotal size, fertility, FSH, LH and testosterone concentrations were determined by immunizing adult rams against bovine inhibin alpha 1-26-Gly-Tyr conjugated to human serum albumin (n = 16) in non-ulcerative Freund's adjuvant and DEAE:dextran (1:1) or adjuvant alone (n = 16) on days 0 (29 June), 30, 60, 191, 303 and 394. Blood samples were collected and bovine inhibin alpha 1-26-Gly-Tyr antibody titres and serum testosterone concentrations were determined. Each month, between days 174 and 417, semen was collected every 30 min to a maximum of 15 ejaculates over 7 h and scrotal circumference was measured. Ram fertility was recorded during natural service. FSH, LH and testosterone concentrations and GnRH-induced FSH and LH release were measured in a subgroup of immunized (n = 5) and control (n = 5) rams at frequent intervals. Antibody titres were variable among immunized rams (0-46% 125I-labelled bovine inhibin alpha 1-26-Gly-Tyr at 1:1600 serum dilution) but mean titres were consistently higher than in control rams (P < or = 0.001). Immunization did not alter the semen volume, output or quality of spermatozoa or ram fertility, but increased the mean scrotal circumference (37.6 +/- 0.8 cm versus 34.4 +/- 0.7 cm, P < 0.001). Mean FSH concentrations were higher in immunized rams during two intensive blood sampling periods (in June and August) (5.8 +/- 0.7 ng ml-1 versus 3.0 +/- 0.3 ng ml-1, P < 0.001 in June; and 4.8 +/- 0.9 ng ml-1 versus 2.0 +/- 0.3 ng ml-1, P < 0.02 in August), and were correlated with antibody titres (r2 = 0.3, P < 0.05 in June; and r2 = 0.8, P < 0.001 in August). Discrete FSH pulses were not detected. Immunization did not alter mean or basal testosterone or LH concentrations, or LH pulse frequency; LH pulse amplitude was increased (1.6 +/- 0.2 ng ml-1 versus 0.8 +/- 0.2 ng ml-1, P < 0.02) and was correlated with antibody titres (r2 = 0.6, P < 0.01). Immunization enhanced GnRH-induced FSH (P < 0.05) but not LH release. In conclusion, immunization of adult rams against bovine inhibin alpha 1-26 Gly-Tyr increased scrotal circumference, mean FSH concentrations and LH pulse amplitude, without altering semen characteristics, fertility, mean LH concentrations, LH pulse frequency or mean testosterone concentrations.

Investigation of the Actinobacillus actinomycetemcomitans genome by pulsed field gel electrophoresis

Pulsed field gel electrophoresis was used to investigate nineteen strains of Actinobacillus actinomycetemcomitans. The genome was found to contain a single chromosome whose size we estimate to be 2300 kb from the sum of restriction fragments generated with rare cutting endonucleases. We detected the presence of large plasmids with sizes ranging from 35 to 300 kb. In some strains, extrachromosomal elements constitute over 20% of the total genome. Comparison of the profiles of ApaI digests of the 19 strains showed a high degree of polymorphism with 13 different profiles, providing a new tool for epidemiological studies.

Response of Brucella suis 1330 and B. canis RM6/66 to growth at acid pH and induction of an adaptive acid tolerance response

Acid pH is an environmental stress often encountered by Brucella during both the "environmental" and the "pathogenic" stages of its life. We have investigated the behaviour of B. suis biovar 1 and B. canis in acid conditions. Growth at suboptimal pH was characterized by a dramatic reduction in growth yield due to an early onset of stationary phase. B. suis was more resistant to low pH than B. canis, which lysed at pH 4.6. Viable counts measured after a 4-h acid shock at pH 3.2 showed that the relative survival of B. suis was 1,000-fold greater than that of B. canis. An adaptive acid tolerance response (ATR) was induced in both species by culture at pH 5.8; however, while the acid-sensitive B. canis had more than a 2,000-fold increase in survival following acid shock at pH 3.2, the increase in survival of B. suis was only around 50-fold. The kinetics of the induction of ATR were followed: for B. suis, 1-2 h (1 generation) at pH 5.8 were required to induce acid tolerance (50-fold protection), and these levels remained constant over 24 h. B. canis became relatively acid-resistant after only 30-min exposure to pH 5.8. Levels of acid tolerance continued to increase and were maximal at 24 h. Stationary phase pH 7.2 cultures of either species did not exhibit acid resistance, suggesting that, like Salmonella, Brucella does not have an rpoS-controlled stationary phase acid resistance.