Haemostatic resuscitation in practice: a descriptive analysis of blood products administered during Operation HERRICK, Afghanistan

INTRODUCTION

Life-threatening haemorrhage is the leading cause of potentially survivable injury in battlefield casualties. During Operation HERRICK (Afghanistan), mortality rates improved year on year due to a number of advances in trauma care, including haemostatic resuscitation. Blood transfusion practice has not previously been reported in detail during this period.

METHODS

A retrospective analysis of blood transfusion at the UK role 3 medical treatment facility (MTF) at Camp Bastion between March 2006 and September 2014 was performed. Data were extracted from two sources: the UK Joint Theatre Trauma Registry (JTTR) and the newly established Deployed Blood Transfusion Database (DBTD).

RESULTS

3840 casualties were transfused 72 138 units of blood and blood products. 2709 adult casualties (71%) were fully linked with JTTR data and were transfused a total of 59 842 units. Casualties received between 1 unit and 264 units of blood product with a median of 13 units per patient. Casualties wounded by explosion required almost twice the volume of blood product transfusion as those wounded by small arms fire or in a motor vehicle collision (18 units, 9 units, and 10 units, respectively). More than half of blood products were transfused within the first 2 hours following arrival at the MTF. There was a trend towards balanced resuscitation with more equal ratios of blood and blood products being used over time.

CONCLUSION

This study has defined the epidemiology of blood transfusion practice during Operation HERRICK. The DBTD is the largest combined trauma database of its kind. It will ensure that lessons learnt during this period are defined and not forgotten; it should also allow further research questions to be answered in this important area of resuscitation practice.

Medical leadership in the military and NHS: what transferable lessons can be identified?

In this article, I explore the different ways leadership in healthcare is taught and developed by the British Army and National Health Service. What lessons and elements of best practice can be taken from each sector, and does traditional infantry-based leadership advice easily translate to civilian healthcare practice?

The UK defence anaesthesia experience with the Zambia Anaesthesia Development Programme

For 18 months UK military anaesthetic trainees have been travelling to Zambia for a 3-month fellowship under the auspices of the Zambia Anaesthesia Development Programme. In this article we will discuss the history, current state and future intent of the fellowship in order to better inform the anaesthetic cadre and wider UK Defence Medical Services.

The discovery of a galaxy-wide superwind from a young massive galaxy at redshift z ≈ 3

High-velocity galactic outflows, driven by intense bursts of star formation and black hole accretion, are processes invoked by current theories of galaxy formation to terminate star formation in the most massive galaxies and to deposit heavy elements in the intergalactic medium. From existing observational evidence (for high-redshift galaxies) it is unclear whether such outflows are localized to regions of intense star formation just a few kiloparsecs in extent, or whether they instead have a significant impact on the entire galaxy and its surroundings. Here we present two-dimensional spectroscopy of a star-forming galaxy at redshift z = 3.09 (seen 11.5 gigayears ago, when the Universe was 20 per cent of its current age): its spatially extended Lyalpha line emission appears to be absorbed by H i in a foreground screen covering the entire galaxy, with a lateral extent of at least 100 kpc and remarkable velocity coherence. This screen was ejected from the galaxy during a starburst several 10(8) years earlier and has subsequently swept up gas from the surrounding intergalactic medium and cooled. This demonstrates the galaxy-wide impact of high-redshift superwinds.

Comparative analyses of Pasteurella multocida strains associated with the ovine respiratory and vaginal tracts

Thirty-five isolates of Pasteurella multocida from the vagina and respiratory tract of sheep were compared by analysing their capsular polysaccharide types and outer membrane protein profiles. The phylogenetic relationships of selected isolates with respect to reference strains of P. multocida were also determined by comparative 16S rRNA sequence analysis. Three capsular types, A, D and F, and three major outer membrane protein types were identified, and there were four different combinations of these characteristics which probably marked four individual clones of P. multocida. Strains representing three of these clones were recovered from cases of ovine pneumonia, whereas isolates of the fourth clone were associated exclusively with the vagina of healthy ewes and the liver of a dead septicaemic lamb on the same farm. Analysis of the 16S rRNA sequences showed that there was 100 per cent identity between representative pneumonic isolates and reference strains of P. multocida subspecies galliseptica and P. multocida subspecies multocida. The 16S rRNA genes of representative vaginal and liver isolates from the same farm were identical but differed from the other strains at one nucleotide position, providing strong evidence that the vaginal and liver isolates represent a distinct subpopulation of P. multocida.

Sequence diversity and molecular evolution of the leukotoxin (lktA) gene in bovine and ovine strains of Mannheimia (Pasteurella) haemolytica

The molecular evolution of the leukotoxin structural gene (lktA) of Mannheimia (Pasteurella) haemolytica was investigated by nucleotide sequence comparison of lktA in 31 bovine and ovine strains representing the various evolutionary lineages and serotypes of the species. Eight major allelic variants (1.4 to 15.7% nucleotide divergence) were identified; these have mosaic structures of varying degrees of complexity reflecting a history of horizontal gene transfer and extensive intragenic recombination. The presence of identical alleles in strains of different genetic backgrounds suggests that assortative (entire gene) recombination has also contributed to strain diversification in M. haemolytica. Five allelic variants occur only in ovine strains and consist of recombinant segments derived from as many as four different sources. Four of these alleles consist of DNA (52.8 to 96.7%) derived from the lktA gene of the two related species Mannheimia glucosida and Pasteurella trehalosi, and four contain recombinant segments derived from an allele that is associated exclusively with bovine or bovine-like serotype A2 strains. The two major lineages of ovine serotype A2 strains possess lktA alleles that have very different evolutionary histories and encode divergent leukotoxins (5.3% amino acid divergence), but both contain segments derived from the bovine allele. Homologous segments of donor and recipient alleles are identical or nearly identical, indicating that the recombination events are relatively recent and probably postdate the domestication of cattle and sheep. Our findings suggest that host switching of bovine strains from cattle to sheep, together with inter- and intraspecies recombinational exchanges, has played an important role in generating leukotoxin diversity in ovine strains. In contrast, there is limited allelic diversity of lktA in bovine strains, suggesting that transmission of strains from sheep to cattle has been less important in leukotoxin evolution.

Distribution of hepatic venous blood in the total cavo-pulmonary connection: an in vitro study

OBJECTIVES

The objective of this project was to quantify the effects of geometry on the distribution of hepatic blood to the lungs in patients with a total cavo-pulmonary connection. The basis for this work is the supposition that hepatic blood is necessary for proper lung function.

METHODS

Plastic models of these connections were made with varying degrees of offset between the inferior and superior vena cava and attached to an in vitro flow loop. Dye was injected into the inferior vena cava and its concentration quantified in each pulmonary artery. These data were converted to percentage concentration and distribution of hepatic blood to each lung.

RESULTS

With no offset between the vena cava, hepatic blood distribution and concentration to each lung was similar to normal. For an offset of one or more diameters, hepatic blood tended to flow preferentially towards the nearest pulmonary artery with the opposite pulmonary artery exhibiting a deficit (<10% of normal).

CONCLUSIONS

Distribution of hepatic blood to each lung was found to be a function of vena cava offset and pulmonary artery flow split. Under normal conditions, 60% of blood towards the right pulmonary artery, the hepatic blood distribution to both lungs could be maintained above 50% of normal if the inferior vena cava was offset towards the left pulmonary artery. Offsetting the inferior vena cava towards the right pulmonary artery jeopardized the delivery of hepatic blood to one lung.

Evolutionary genetics of Pasteurella haemolytica isolates recovered from cattle and sheep

Genetic diversity and relationships among 194 Pasteurella haemolytica isolates, which were recovered predominantly from cattle (39%) and sheep (58%) suffering from pneumonic pasteurellosis in the United Kingdom, Germany, and the United States, were estimated by examination of allelic variation at 18 enzyme-encoding loci detected by multilocus enzyme electrophoresis. The isolates formed two major divisions. One included 178 Pasteurella haemolytica sensu stricto strains representing serotypes A1, A2, A5 to A9, A12 to A14, and A16; the other was composed of 16 isolates belonging to the A11 taxon. P. haemolytica isolates were classified into 22 electrophoretic types (ETs) that formed three primary phylogenetic lineages. One lineage was represented by ovine serotype A2 isolates, a second lineage consisted of bovine serotype A2, together with serotype A7 and A13 isolates, and the third lineage included isolates representing all of the other serotypes, as well as a second group of serotype A7 strains. Electrophoretic types were nonrandomly associated with specific capsular serotypes, lipopolysaccharide (LPS) types, outer membrane protein (OMP) types, and host species. Bovine isolates were represented by only three serotypes (A1, A2, and A6) in 5 ETs, whereas ovine isolates were represented by all of the serotypes in 19 ETs. The majority (76%) of bovine isolates were of serotypes A1 or A6 and belonged to a single ET that marked a virulent, cattle-specific clonal group. Among the ovine isolates, 40% were of serotype A2 and belonged to two ETs that represented two virulent, sheep-specific clonal groups. Bovine A1 and A6 isolates and bovine A2 isolates were phylogenetically distinct from ovine isolates of the same serotypes, indicating that different subpopulations of these serotypes are associated with disease in cattle and sheep. Consistent differences in the OMP profiles of strains of the bovine and ovine lineages of these three serotypes suggest that certain OMPs are involved in host specificity and virulence. Evolutionary relationships among P. haemolytica isolates indicate that the ancestral host is the sheep and that several distinct clonal lineages have crossed the species barrier into cattle. The A11 taxon is a heterogeneous group of opportunistic pathogens of sheep that represents a separate species.

Phylogenetic relationships and diversity within the Pasteurella haemolytica complex based on 16S rRNA sequence comparison and outer membrane protein and lipopolysaccharide analysis

The outer membrane protein (OMP) and lipopolysaccharide (LPS) profiles of 30 untypeable isolates of Pasteurella haemolytica were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and compared with the profiles of typeable isolates. The phylogenetic relationships of 28 isolates representing each of the serotypes of P. haemolytica and Pasteurella trehalosi, as well as untypeable isolates of P. haemolytica, were determined by comparing 16S rRNA sequences. The analysis of the OMP and LPS profiles of the untypeable isolates revealed five groups, which were designated untypeable groups 1 (UG1) through UG5. The UG1 and UG2 isolates had OMP and LPS profiles identical to the profiles of certain serotype A1 and A2 isolates, respectively. Furthermore, UG1 isolates originating from cattle and sheep could be clearly differentiated on the basis of their OMP profiles. The OMP and LPS profiles of UG3 isolates were similar appearance to the profiles of serotype A11 isolates, suggesting that these two groups are closely related. The OMP profiles of UG4 and UG5 isolates were unique and different from the OMP profiles of the UG1 through UG3 isolates. A comparison of 16S rRNA sequences revealed that typeable isolates of P. haemolytica could be divided into the following three groups: (i) serotype A1, A5 through A9, A12 through A14, and A16 isolates, (ii) serotype A2 isolates, and (iii) serotype A11 isolates. the isolates belonging to the first group all had identical sequences, whereas the sequences of isolates belonging to the second and third groups differed from the sequences of the isolates belonging to the first group at two and four base positions, respectively. The sequence data for the untypeable isolates confirmed the conclusions derived from the OMP and LPS analysis. Isolates belonging to UG1 and UG2 were identical to serotype A1 and A2 isolates, respectively; isolates belonging to UG3 were related to serotype A11 isolates, although there was some sequence heterogeneity within this group; and isolates belonging to UG4 and UG5 were more distantly related to P. haemolytica than were isolates belonging to UG1 through UG3 and were clearly members of two different species. As expected, isolates of P. trehalosi were event more distantly related to P. haemolytica than were the untypeable isolates, but there was significantly more sequence variation among the four serotypes of this species than there was among the serotypes of P. haemolytica. The correlation of the OMP and LPS data with the 16S rRNA sequence data suggested that OMP and LPS analyses might be useful for preliminary screening and comparing large numbers of isolates in taxonomic and epidemiological studies of the Pasteurellaceae.

Intra-specific diversity and host specificity within Pasteurella haemolytica based on variation of capsular polysaccharide, lipopolysaccharide and outer-membrane proteins

Intra-specific diversity within Pasteurella haemolytica was assessed by analysing variation in the capsular polysaccharide (serotypes), lipopolysaccharide (LPS) and outer-membrane proteins (OMPs) of 184 isolates recovered from cattle and sheep. Four 12 serotypes comprised 83% of the total number of isolates, including A1 and A2 as the most frequently recovered serotypes from cattle and sheep, respectively. Nine distinct LPS profiles were identified. Four different core-oligosaccharide patterns were present, each of which occurred alone as rough LPS and also in association with single O-antigen profile as smooth LPS; the ninth LPS type was also smooth but had a different O-antigen profile. The capsular serotypes could be divided into four groups based on the dominant LPS profile within each serotype: (1) A1, A6, A9, A12 and A5; (2) A2, A8, A14 and A16; (3) A7 and A13; and (4) A11. Smooth LPS of type 1A, which was found only in the first group, was associated primarily with bovine disease isolates, whereas rough LPS of types 1B and 3B were associated primarily with group 2 serotypes and ovine disease isolates. Similarly, the variation of OMP profiles generated three groups: (1) A1, A6 A9, A12, A5 and A8; (2) A2, A14 and A16; and (3) A7, A11 and A13. Isolates belonging to groups 2 and 3 exhibited greater diversity in their OMP profiles than those belonging to group 1. Although the majority of group 3 isolates possessed profiles unique to that group, a smaller number of A7 isolates possessed profiles with similarities to those of serotypes A1 or A2. OMP profiles clearly differentiated bovine from ovine isolates of the same serotypes. The association both of specific LPS and OMP profiles with bovine or ovine disease isolates suggested a correlation between specific cell-surface structures and host specificity. The combined analysis of capsular serotypes, LPS types and OMP profiles identified seven major groups within P. haemolytica which were responsible for 59% of the disease cases, suggesting a clonal structure for this species. Overall, comparison of the capsular serotypes, LPS types and OMP profiles proved extremely useful for assessing diversity within P. haemolytica.

Intra-specific diversity within Pasteurella trehalosi based on variation of capsular polysaccharide, lipopolysaccharide and outer-membrane proteins

Intra-specific diversity within Pasteurella trehalosi was investigated by analysis of variation of capsular polysaccharide, and lipopolysaccharide (LPS) and outer-membrane protein (OMP) profiles. Sixty isolates of P. trehalosi, from diverse geographical locations within the UK, were examined. Capsular polysaccharide serotypes were determined by indirect haemagglutination assay; LPS and OMP profiles were compared by SDS-PAGE analysis. Capsular serotyping identified three isolates of serotype T3, 18 isolates each of serotypes T4, T10 and T15, and three untypable (UT) isolates. Analysis of LPS and OMP profiles identified six smooth LPS types and four OMP types among the 60 isolates. Forty-five (75%) of the isolates belonged to a single OMP type whereas 52 (87%) of the isolates possessed one of three LPS types. Each typing method, by itself, was not very discriminating but when the data from the three methods were combined, the 60 isolates could be separated into 14 distinct subgroups containing from one to 16 isolates as follows: serotype T3, two subgroups; serotype T4, four subgroups; serotype T10, two subgroups; serotype T15, five subgroups; UT isolates, one subgroup. Certain subgroups were associated with only one serotype whereas other subgroups were common to two or more serotypes. The subgroupings were capable of differentiating between isolates of the same serotype from the same and different geographical origins. Based on their LPS and OMP profiles, isolates of serotypes T4 and T15 were more closely related to each other than to isolates of serotype T10; serotype T4 and T15 isolates were also more heterogeneous than those of serotype T10. Certain isolates of serotype T10, recovered from a wide geographical area, were characterized by the possession of a unique capsule/LPS/OMP combination and represented a single clonal group which was responsible for a large proportion (31%) of recent disease outbreaks. Overall, a combination of capsular serotyping, and LPS and OMP typing, was found to be extremely useful for assessing diversity within P. trehalosi and should be of value for epidemiological and virulence studies.

Physical mapping of the human ELA1 gene between D12S361 and D12S347 on chromosome 12q13

ELA1, the pancreatic elastase 1 gene, is conserved in mammalian genomes. ELA1 was previously mapped to chromosome 12 using a panel of mouse-human somatic cell hybrids. We now report the physical and cytogenetic localization of the ELA1 gene. On the physical map, ELA1 is adjacent to the polymorphic marker AFMa283yg1 and between D12S361 and D12S347. Using fluorescence in situ hybridization, we determined that ELA1 maps to 12q13.

Comparison of outer-membrane proteins of Pasteurella haemolytica expressed in vitro and in vivo in cattle

Outer-membrane protein (OMP) profiles of two serotype A1 isolates of Pasteurella haemolytica were compared by SDS-PAGE and Western blotting with bovine convalescent serum after growth (a) in vitro under iron-sufficient and -deficient conditions, (b) in vivo in the lungs of experimentally infected calves and (c) in vivo in diffusion chambers implanted into the peritoneal cavities of calves. Lung-grown bacteria differed from iron-sufficient in vitro-grown bacteria in having enhanced expression of the previously recognized 71, 77 and 100 kDa iron-regulated proteins, reduced expression of 18, 31, 39.5 and 50 kDa proteins, and expression of a 19 kDa protein. Differences were also apparent in the Western blot profiles of OMPs of in vitro- and lung-grown bacteria. These included the apparent lack of recognition of the 100 kDa protein in the lung-grown bacteria, but not in the in vitro-grown bacteria, and more intense staining of a 47 kDa protein in in vitro-grown bacteria, but not in lung-grown bacteria. The OMP profiles of the chamber-grown bacteria resembled those of the lung-grown bacteria in that expression of the 18, 19, 31 and 39.5 kDa proteins was similar. These similarities demonstrated that the chamber-grown bacteria had adapted to the in vivo environment, and that growth conditions within the chambers resembled, but not perfectly, those within the lungs. For example, expression of the three iron-regulated OMPs was very low in the chamber-grown bacteria compared to the lung-grown bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of an intraperitoneal implant chamber for the study of in vivo-grown Pasteurella haemolytica in cattle

An intraperitoneal implant chamber was developed for the study of the in vivo growth of Pasteurella haemolytica in calves. The chamber had a volume of approximately 100 ml and featured an external sampling port which allowed multiple and sequential sampling of the chamber contents. A single polycarbonate diffusion membrane with a pore size of 0.22 micron allowed host peritoneal fluid to diffuse into the chamber and maintained the bacterial population free of white blood cells. Chambers were implanted into the peritoneal cavities of four five-month-old dairy-cross calves, demonstrated to be sero-negative by indirect haemagglutination assay. Three days later, four different P. haemolytica isolates, of serotypes A1 or A2, were inoculated into the chambers. In all cases, there was a slow decline in the viable bacterial numbers within the chambers. Western blot analysis of the antibody content of the chamber fluids revealed IgG antibodies to P. haemolytica OMPs in the fluid prior to inoculation and both 9 and 15 days after inoculation. Furthermore, there was no significant change in the IgG antibody content of the chamber fluid, either quantitatively or qualitatively, during the course of the experiment. Analysis of the bactericidal activity of pre-inoculation chamber fluid against the corresponding bacterial isolate suggested that an antibody-dependent complement-mediated process was not responsible for the decline in bacterial numbers. Overall, the chamber design was demonstrated to be extremely effective for in vivo studies of P. haemolytica in calves, allowing easy and regular sampling of the chamber contents and maintaining bacteria free of white blood cells. Although there was a slow decline in bacterial numbers over time, sufficient numbers of cells could be obtained for analysis of cell-surface antigens.

Variation in outer-membrane protein and lipopolysaccharide profiles of Pasteurella haemolytica isolates of serotypes A1 and A2 obtained from pneumonic and healthy cattle

The outer-membrane protein (OMP) and lipopolysaccharide (LPS) profiles of 29 isolates of Pasteurella haemolytica serotypes A1 (18 isolates) and A2 (11 isolates), obtained from pneumonic (13 isolates) or healthy (16 isolates) cattle, were compared by SDS-PAGE and Western blot analysis. Coomassie-blue-stained OMP profiles of serotype A1 and A2 isolates could be distinguished from each other by differences in both major and minor proteins. Whereas the OMP profiles of the serotype A1 isolates were extremely uniform in stained gels, there was variation in the mobilities of high-molecular-mass minor proteins and one of the major proteins of serotype A2 isolates. Differences in the OMP profiles of isolates within both the A1 and A2 serotypes were more clearly distinguished by Western blotting than by staining after SDS-PAGE. Thus, by Western blot analysis, four distinct OMP profiles were identified within the serotype A1 and A2 isolates, respectively. The profiles of the serotype A1 isolates were designated OMP types 1.1, 1.2, 1.3 and 1.4; those of the serotype A2 isolates were designated OMP types 2.1, 2.2, 2.3 and 2.4. Three distinct LPS profiles were recognized among the isolates which, by comparison with previously described LPS types, were identified as smooth LPS type 1 and rough LPS types 3 and 5. Isolates of serotype A1 consisted of LPS type 1 only. whereas isolates of serotype A2 consisted of LPS types 3 or 5. OMP and LPS analysis of P. haemolytica has applications in epidemiological and virulence studies.

Evaluation of different methods for the detection of outer membrane proteins and lipopolysaccharides of Pasteurella haemolytica by immunoblotting

The optimal conditions for the detection of outer membrane proteins (OMPs) and lipopolysaccharide (LPS) of Pasteurella haemolytica by immunoblotting were evaluated. The variables examined included the equilibration time of the gels before transfer, composition of the transfer buffer, type of blotting membrane, blocking agent, effect of the zwitterionic detergent Empigen BB on protein renaturation, and the development reagent. The composition of the transfer buffer and time of gel equilibration significantly affected the efficiency of transfer of both OMPs and LPS. However, the optimal conditions for the transfer of OMPs were not the same as those for LPS. Thus, optimal transfer of OMPs occurred in Tris-glycine buffer, with prior equilibration of the gels to allow for expansion, whereas optimal transfer of LPS was achieved in Tris-glycine-methanol buffer with no equilibration of the gels. In Tris-glycine-methanol buffer, gel equilibration resulted in a significantly reduced transfer of both OMPs and LPS, probably due to the removal of SDS from these components. The use of Zeta-Probe blotting membrane which, unlike nitrocellulose, does not require methanol for optimal protein binding, did not result in improved binding of OMPs or LPS in the absence of methanol and, even after prolonged blocking (> 2 h), gave higher background staining than did nitrocellulose. Effective blocking of nitrocellulose was achieved with 3% (w/v) gelatin, 2.5% (w/v) skimmed milk or 0.3% (v/v) Tween 20, whereas increased background staining occurred with 1% (w/v) bovine serum albumin or 1% (w/v) ovalbumin. The incorporation of Empigen BB in the primary antibody buffer did not improve antibody recognition of proteins as a result of their renaturation. For the horseradish-peroxidase enzyme development system, the substrate 3,3'-diaminobenzidine tetrahydrochloride was more sensitive, and developed more quickly, than 4-chloro-1-naphthol, but faded more rapidly after drying of the membrane. 4-chloro-1-naphthol was more suitable for identifying OMPs because less background staining occurred, whereas 3,3'-diaminobenzidine tetrahydrochloride was more suitable for the detection of LPS due to its greater sensitivity.

Lipopolysaccharide heterogeneity in Pasteurella haemolytica isolates from cattle and sheep

Lipopolysaccharide (LPS) from 40 isolates of Pasteurella haemolytica, comprising 23 serotype A1, seven serotype A2, one serotype T4, one serotype T10 and eight untypable isolates, obtained from diseased and healthy cattle or sheep, was characterized by SDS-PAGE and Western blotting. Ten different SDS-PAGE LPS profiles, five smooth and five rough, were identified among the biotype A and untypable isolates and designated LPS types 1-10. LPS types 1 and 2 were smooth, had similar O-antigen banding-patterns but differed in the low-molecular-mass or core-oligosaccharide regions; type 3 LPS was rough but had a core-oligosaccharide region similar to that of LPS type 1. No similarities were observed between these LPS types and types 6, 7 and 9, which were smooth, and types 4, 5, 8 and 10, which were rough. Most serotype A1 isolates (19/23) were of LPS type 1, whereas two isolates each had LPS of types 2 and 3. The majority (5/7) of serotype A2 isolates possessed type 3 LPS, whereas the remaining two isolates each had LPS of types 4 and 5. There was much greater heterogeneity within the untypable group of isolates, which comprised LPS of types 1 and 9 (two isolates each), and 6, 7, 8 or 10 (one isolate each). Western blotting analysis demonstrated that LPS types 1 and 2 had immunologically identical O-antigen side-chains but differed in their core-oligosaccharide regions, whereas the core-oligosaccharide region of rough LPS type 3 was immunologically very similar to that of LPS type 1. The other LPS types were immunologically unrelated to these three LPS types. The majority (20/23) of serotype A1 isolates originated from cattle and possessed LPS types 1 or 2, different from most (5/7) of the serotype A2 isolates which originated from sheep and possessed LPS of types 3 or 4. However, two of the three ovine serotype A1 isolates had the same type 3 LPS as occurred in most of the ovine serotype A2 isolates, suggesting a possible correlation between LPS type and host specificity. This study has demonstrated that LPS diversity within different serotypes of P. haemolytica is greater than was previously thought and that certain LPS types might be host-specific.

Effects of intrathecal and intraperitoneal morphine on gastrointestinal motility in the rat

A method has been developed to compare gastrointestinal (GI) transit time after intrathecal (i.t.) drug injection in the rat. Each animal had a catheter implanted in the i.t. space. Eight rats, on three separate occasions, had either i.t. morphine 16 micrograms kg-1 (in 50 microliters) or intraperitoneal (i.p.) morphine (0.1%) 7.5 mg kg-1 or i.t. saline (50 microliters). The dose of morphine was the ED50 for analgesia by each route. After halothane and oxygen anaesthesia, 10 steel balls and 1 ml of contrast medium were placed into the stomach, the whole procedure being completed within 5 min. Radiographs were taken at 5 min, 3, 6 and 24 h, and the number of balls in the stomach, small and large intestine were counted. The inhibitory effect of i.t. or i.p. morphine on gut motility caused an equally significant delay at 6 h. In a separate series of eight rats the delay by i.t. morphine could be completely antagonized by i.p. naloxone 1 mg kg-1. Thus, i.t. morphine in an analgesic dose even though smaller than the i.p. dose has a similar inhibitory effect on GI tract motility in the rat. This method would enable comparisons on GI transit to be made between a variety of intrathecally administered drugs.

Outer-membrane protein and lipopolysaccharide variation in Pasteurella haemolytica serotype A1 under different growth conditions

Growth characteristics, as well as outer-membrane protein (OMP) and lipopolysaccharide (LPS) profiles in SDS-polyacrylamide gels, of two serotype A1 isolates of Pasteurella haemolytica were examined under different in vitro growth conditions. The two isolates were chosen as representatives of disease (S/C 82/1) and non-disease (W/D 83/4) isolates, respectively. The growth rates and final cell densities of both isolates increased as the degree of aeration increased. In particular, the final cell densities varied significantly according to the degree of aeration. Under anaerobic conditions, however, both the growth rate and final cell density were significantly reduced. There was reduced expression of a 40.5 kDa protein under anaerobic conditions in both isolates, whereas in S/C 82/1 expression of the 71, 77 and 100 kDa iron-regulated proteins increased as aeration decreased. There were also differences in low-molecular-mass components of LPS between cells grown anaerobically and those grown aerobically. Growth in the presence of 5% CO2 did not significantly alter the growth rate and had little, if any, affect on OMPs or LPS. Differences in the expression of certain proteins occurred as growth progressed from the exponential to the stationary phase. Growth in the presence of the iron chelators 2,2'-dipyridyl, ethylenediamine-dihydroxyphenylacetic acid (EDDA), desferrioxamine mesylate (desferal), ovotransferrin (conalbumin) and bovine transferrin was inhibited within a very narrow concentration range. In the presence of 2,2'-dipyridyl, EDDA or desferal, 71 and 100 kDa iron-regulated OMPs increased in both isolates whereas a 77 kDa protein increased in isolate S/C 82/1 only. In the presence of ovotransferrin or bovine transferrin there was, in both isolates, increased expression of the 71 kDa protein, a slight increase in expression of the 100 kDa protein but no expression of the 77 kDa protein; there was also increased production of the 40.5 kDa protein, and synthesis of two additional proteins of 23 and 26 kDa. Other differences occurred after growth in foetal and newborn calf sera. In foetal calf serum there was enhanced expression of the 71 but not of the 100 kDa protein. In newborn calf serum there was no enhanced expression of the 71, 77 or 100 kDa proteins, but expression of novel proteins of 97 and 98 kDa as well as a high-molecular-mass protein occurred. There was also slight quantitative differences in the LPS profiles of cells grown in foetal or newborn calf sera compared to those of cells grown in other media.(ABSTRACT TRUNCATED AT 400 WORDS)

Optimal conditions for the analysis of Pasteurella haemolytica lipopolysaccharide by sodium dodecyl sulphate-polyacrylamide gel electrophoresis

The optimal conditions for the analysis of the lipopolysaccharide (LPS) of two serotype A1 isolates and a serotype A2 isolate of Pasteurella haemolytica by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining were determined. The LPS of the A1 isolates possessed O side chains, consisting of high molecular mass bands with the appearance of a ladder-like pattern, as well as a low molecular mass core-oligosaccharide region; the LPS of the A2 isolate consisted only of the core-oligosaccharide region. Furthermore, the LPS of the two A1 isolates differed in the core-oligosaccharide region. Optimal resolution of low molecular mass LPS components was obtained in a 15% acrylamide resolving gel containing 4 M urea whereas optimal resolution of high molecular mass components was obtained when urea was omitted. Conventional silver staining resulted in excellent visualisation of LPS bands, whereas a modified staining method did not detect additional bands, as has been demonstrated with the LPS of Pseudomonas aeruginosa. Proteinase K digestion of outer membranes gave more clearly defined LPS profiles than did similar digestions of whole cells, and more closely resembled the profiles of purified LPS. With the exception of slight variation in the average molecular mass of a group of O side chains between logarithmic and stationary phases there were no differences in LPS profiles at various stages of the growth cycle; freezing and thawing of LPS samples had no effect on the profiles.

Virulence and serum-resistance in different clonal groups and serotypes of Yersinia ruckeri

The virulence in rainbow trout (Oncorhynchus mykiss) of 32 isolates of Yersinia ruckeri, representing a range of biotypes, serotypes, and OMP-types, was examined. Virulence was assayed in fish of average weight 7.7 g by bath challenge for 1 h with approximately 5 x 10(7) cells per ml. Two of the six serotype O1 clonal groups of Y. ruckeri, clones 2 and 5, were virulent, whereas the other four clonal groups, clones 1, 3, 4 and 6, as well as all serotype O2, O5, O6 and O7 isolates examined, were avirulent. Analysis of susceptibility to the bactericidal effect of non-immune rainbow trout serum demonstrated an association between virulence and serum resistance. The virulent serotype O1 clonal groups were serum resistant, whereas the avirulent serotype O1 clonal groups and other serotypes were, with some exceptions, serum sensitive. The fact that some serum resistant isolates were avirulent suggested that other factors may be required for the full expression of virulence. The study also demonstrated that rainbow trout and brook trout (Salvelinus fontinalis) differ in their susceptibility to Y. ruckeri.

Effects of regional myocardial ischaemia on coronary artery calibre in the rabbit

Microangiographic and electron microscopic studies were undertaken in isolated, perfused rabbit hearts to examine the effects of acute regional myocardial ischaemia on coronary artery calibre, vascular resistance and ultrastructure. Selective left coronary angiograms were recorded prior to, after 90 min of acute regional myocardial ischaemia induced by occlusion of the marginal left ventricular branch of the circumflex artery, and after reperfusion for 5 min. Vasodilation occurred in the proximal left anterior descending artery (9 +/- 1%, P less than 0.01) and the unoccluded part of the marginal branch (21 +/- 1%, P less than 0.001) during ischaemia which reversed on reperfusion. During reperfusion, coronary vascular resistance increased by 43 +/- 10% (P less than 0.001) despite mild vasodilation of vessels in the ischaemic zone (up to 10 +/- 1%, P less than 0.01). Failure of reperfusion occurred in vessels smaller than 30 microns in diameter (terminal arterioles) and was associated with ultrastructural damage in the ischaemic zone which was particularly prominent at the apex. These findings suggest that failure of reperfusion following 90 min of acute regional myocardial ischaemia in the rabbit is associated with damage to terminal arterioles and capillaries and that the calibre of the larger coronary vessels is maintained. Failure of reperfusion after prolonged myocardial ischaemia may occur despite arterial dilatation in the ischaemic zone.

The protective role of eicosapentaenoic acid [EPA] in the pathogenesis of nephrolithiasis

The low incidence of atherosclerosis and other degenerative diseases including stone disease in the Greenland Eskimo has been attributed to their high consumption of oily fish with its high concentration of eicosapentaenoic acid (EPA). Man cannot synthesis EPA from the precursor essential fatty acid, linolenic acid, and can only assimilate preformed EPA present in fish and fish oil, to bring about a change in the pathway of eicosanoid metabolism from the n-6 to the n-3 series. With a westernised diet the oxygenated products of renal prostaglandin synthesis are metabolites of the n-6 series and these are known to play an important role in several pathophysiological states including stone disease. Our previous studies have shown a relationship between prostaglandin activity and urinary calcium excretion and it would seem that the initiating factor/s for stone formation trigger the mechanisms for prostaglandin synthesis resulting in the biochemical abnormalities associated with stone disease. The Eskimo may be protected from these events by possession of an eicosanoid metabolism that follows an n-3 pathway. To test this hypothesis experiments were performed using an animal model of nephrocalcinosis. The animals were divided into three groups; one group was given an intra-peritoneal injection of 10% calcium gluconate daily for 10 days to induce nephrocalcinosis; a second group was fed MaxEPA fish oil before and during the calcium gluconate injections and a third group only received an intra-peritoneal injection of N saline. A group of 12 recurrent, hypercalciuric/hyperoxaluric stone-formers were treated with fish oil for eight weeks to study the effects on solute excretion. Nephrocalcinosis, which was readily produced in the control animals, was prevented in the experimental animals by pre-treatment with fish oil and urine calcium excretion was significantly reduced. The urinary calcium and oxalate excretion in the recurrent, hypercalciuric stone-formers was significantly reduced with fish oil treatment over an eight week period. There were no untoward side-effects. These studies indicate that the incorporation of EPA in the diet as a substitute metabolic pathway could be a unique way of correcting the biochemical abnormalities of idiopathic urolithiasis.

Outer membrane protein profiles of Yersinia ruckeri

The outer membrane protein (OMP) profiles of 135 isolates of Yersinia ruckeri, obtained from nine European countries (100 isolates), North America (23 isolates), Australia (six isolates) and South Africa (two isolates), and including four reference strains, were examined by SDS-PAGE. Outer membranes were isolated by selective solubilisation of the cytoplasmic membrane with 0.5% (w/v) sodium N-lauroyl sarcosinate (Sarkosyl). Outer membrane proteins were stable after in vitro passage and there was no variation in OMP profiles due to colony selection. With the exception of a 39.5 kDa peptidoglycan-associated protein there was also no variation at different stages of the growth cycle. The 39.5 kDa protein was not produced during logarithmic growth phase but increased in abundance as the stationary phase progressed. Interstrain variation occurred in the possession of a 36.5 or 38 kDa heat-modifiable protein and in the possession of peptidoglycan-associated proteins in the molecular weight range 36.5 to 40.5 kDa. Based on variation of these proteins five OMP-types, designated OMP-types 1-5, were identified among the 135 isolates examined. Outer membrane protein analysis was demonstrated to be useful in epidemiological studies of Y. ruckeri.

Comparison of methods for the analysis of outer membrane antigens of Neisseria meningitidis by western blotting

The method of extraction of outer membrane proteins (OMPs), the conditions of electrophoretic transfer, and the conditions of antibody binding, were compared in Western blotting studies of Neisseria meningitidis outer membrane antigens. The OMP profiles obtained by SDS-PAGE of outer membrane vesicles extracted with lithium chloride/sodium acetate were compared with profiles obtained by Sarkosyl extraction; these profiles were further compared with the patterns obtained by 125I-labelling of surface-exposed proteins. Sarkosyl extracts gave profiles most closely resembling those of 125I-labelled whole-cells and gave the best resolution of the major proteins. After transfer in Tris-glycine-methanol buffer some proteins, including the major proteins, were not completely transferred and remained in the gel, with the class 2/3 and 5 proteins not effectively detected on nitrocellulose by amido black staining. There was weak antibody recognition of the class 1 and 4 proteins but good recognition of lipooligosaccharide (LOS) and H8 antigen. Empigen BB had no effect on renaturation of the class 1 protein. When 0.1% SDS was incorporated in the same buffer all of the proteins were removed from the gel, and although the major proteins bound to nitrocellulose other proteins did not. There was weak antibody recognition of the class 1 and 4 proteins, stronger reaction to the class 5 protein, but no recognition of the class 2 protein, LOS or H8 antigen, Empigen BB slightly enhanced antibody recognition of the class 1 protein. After transfer in Tris-glycine buffer, all the major proteins were transferred and bound to nitrocellulose and, other than the class 2 protein, were recognised by antibody, both in the presence or absence of Empigen BB, as were LOS and the H8 antigen. Differences existed in the patterns of antibody recognition between the lithium and the Sarkosyl extracts; additional proteins were recognised in the lithium extracts. The surface-labelling studies indicated, however, that some of these proteins were not surface-exposed. Some minor proteins appeared to be more highly immunogenic than the major proteins.

Origin and structure of benign prostatic hyperplasia

The development of microradiography of the prostate gland has provided a new approach to investigating the origin and structure of benign hyperplasia. It has demonstrated that benign prostatic hyperplasia is usually microadenomatous in structure, although reticular types do occur. It originates at the lateral boundary of the periurethral muscle in the position of the transitional zone. In contrast, stromal nodules are homogeneous and amorphous in structure and develop at the site of the short straight urethral ducts within the periurethral muscle.

Human cytochrome P450IIA3: cDNA sequence, role of the enzyme in the metabolic activation of promutagens, comparison to nitrosamine activation by human cytochrome P450IIE1

We report that, in a human cell line, human cytochrome P450IIA3 is capable of metabolizing aflatoxin B1, benzo[a]-pyrene, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) to cytotoxic and mutagenic species. Cytochrome P450IIA3-mediated activation of NDMA and NDEA was compared with human cytochrome P450IIE1-mediated activation in the same cell system. P450IIE1 was more effective at activating NDMA than P450IIA3, while P450IIA3 was more effective at activating NDEA than P450IIE1. Whole cells and microsomal fractions obtained from control cells and from cells expressing the P450IIA3 cDNA were characterized for expression of P450IIA3. Microsomal coumarin 7-hydroxylase activity was some 40 times greater in the transfected cells than in the control cells and was catalyzed by a protein that was immunochemically related to the rat liver cytochrome P450IIA gene family. Immunoblot analysis demonstrated that this protein was readily detectable in transfected cells but barely detectable in control cells. We also report the DNA and deduced amino acid sequence of the P450IIA3 cDNA isolate used in this study. Our isolate encodes a protein 489 amino acids that is five amino acids shorter at the N terminus but otherwise identical to a previously reported human P450IIA3 cDNA sequence.

O-serotyping of Yersinia ruckeri with special emphasis on European isolates

Yersinia ruckeri is the aetiological agent of enteric redmouth disease (ERM), an acute to chronic bacteraemic infection of salmonid fish. The O-serotypes of 127 isolates of Y. ruckeri obtained from Europe (96 isolates), North America (23 isolates), Australia (six isolates) and South Africa (two isolates), as well as four reference strains, were determined by slide agglutination test and microplate agglutination assay. A serotyping scheme is proposed based on heat-stable O-antigens; the serotypes were designated O1, O2, O5, O6 and O7. The proposed scheme is compared to serotyping schemes described by other authors. All five O-serotypes were present in both Europe and North America, whereas only serotype O1 isolates were identified in Australia and South Africa. These findings suggest that European and North American populations of Y. ruckeri are interrelated, thus supporting previous evidence which suggests that the organism was introduced into Europe from North America by the importation of asymptomatic infected carrier fish. Conversely, the results suggest that Australia and South Africa are more isolated from the dissemination of Y. ruckeri. Serotypes O5, O6 and O7 have not previously been recognized in Europe and these findings will have important implications on the diagnosis of ERM and on the vaccination of fish against this disease. It is suggested that the Australian isolate previously described as serotype III is a rough-type mutant and that other isolates described in the literature as serotype III have been incorrectly serotyped and are, in fact, serotype O1. To avoid further confusion it is suggested that the scheme described here be adopted for serological studies of Y. ruckeri.

Structure and per-rectal ultrasonography of prostatic disease using cadaver specimens

One hundred cadaver prostates were examined by per-rectal ultrasound and the findings correlated with the microradiographic and histopathological features of whole sections taken at the levels of scanning. The normal gland consists of both periurethral muscle and glands. The periurethral muscle has little structure on microradiography and is therefore hypoechoic (low amplitude echoes) on ultrasound scanning. The gland itself, both central and peripheral zones, has a lattice appearance on microradiography (reticular structure) and therefore produces mid-range amplitude echoes on ultrasound. Benign hypertrophy develops at the edge of the periurethral muscle and is microadenomatous in structure. This produces mid-range amplitude echoes which are coarser than in the normal gland. Associated calcification has a characteristic distribution around the adenomas. Cancer produces an amorphous structure resulting in loss of ultrasonic echoes (hypoechoic). In a few cancers irregular calcification is present, resulting in high echoes in the ultrasound scan (hyperechoic) which are not in the typical benign distribution. The internal structure of the prostate was therefore demonstrated in its histopathological states by the technique of microradiography and seen to relate to its representation by ultrasound.

The correlation of histopathological, microradiographic and ultrasonographic features in disease of the prostate gland

The histopathological, microradiographic and ultrasonographic features of corresponding areas of 100 cadaveric prostates were examined and correlated statistically to investigate their relationship. Benign glands are seen to be related to reticular structure and mid-range echoes. Benign prostatic hyperplasia is related to microadenomatous structure and mid-range echoes, whilst cancer is related to amorphous structure and low echoes. A small number of cancers have irregular calcification present and these tumours are related to high echoes. The structure of the prostate gland is therefore related to its pathology and explains its ultrasound echogenicity.

Development of a human cell line by selection and drug-metabolizing gene transfection with increased capacity to activate promutagens

We have isolated a human lymphoblastoid cell line with higher levels of native cytochrome P450IA1 activity and by DNA transfection introduced human cDNAs for a putative cytochrome P450IIA2 and epoxide hydrolase (E.C. 3.3.2.3). The resultant cell line, designated MCL-1, was substantially more sensitive to the mutagenicity of dimethylnitrosamine and benzo[a]pyrene than the AHH-1 cell line and was found to have increased metabolism of benzo[a]pyrene to dihydrodiols. The increase in native cytochrome P450IA1 activity was achieved by mutation and selection based on resistance to the phototoxicity of benzo[ghi]perylene. One resistant clone, designated L3, was used for subsequent studies. Two complete cDNAs, one encoding a putative cytochrome P450IIA2 and the other a microsomal epoxide hydrolase, were isolated from a human liver cDNA library. After introduction of the cDNAs into an expression vector and transfection into AHH-1 cells, gene expression was detected at the level of enzyme activity (epoxide hydrolase) or by increased sensitivity to dimethylnitrosamine cytotoxicity/mutagenicity (putative P450IIA2). A vector containing both cDNAs was then constructed and transfected into L3 cells to produce MCL-1 cells. The potential usefulness of drug-metabolizing gene transfection and of the MCL-1 cell line, in particular, for genetic toxicity testing is discussed.

Comparative histopathology, microradiography and per-rectal ultrasonography of the prostate using cadaver specimens

A technique for examining cadaver prostates by per-rectal ultrasonography has been developed. The ultrasonic plane was defined and corresponding sections taken for microradiographic and histopathological examination. The technique has enabled a comparison to be made of the structural changes that occur in the prostate in disease states and the corresponding ultrasonic features.

Adonis microcarpa (pheasant's eye) toxicity in pigs fed field pea screenings

Seed of Adonis microcarpa (pheasant's eye) fed at 5.6 g/kg of the diet induced virtually total feed refusal within 3 d in growing and finishing pigs. It also caused vomiting, rapid and shallow breathing and death in a minority. These effects were probably caused by cardiac glycosides whose structure and effects closely resemble those of digoxin. Feed intake and growth recovered within 2 weeks of removal of the seed.

The role of EDRF in flow distribution: a microangiographic study of the rabbit isolated ear

A microangiographic technique was used to study the influence of endothelium-derived relaxing factor (EDRF) on vasomotor control mechanisms in resistance vessels of intact buffer-perfused rabbit ear. Selective inhibition of EDRF activity by hemoglobin unmasked an intrinsic ("myogenic") constrictor response to sudden increases in flow rate. EDRF activity was greatest in arteries in which calculated shear stress and hydraulic resistance were maximal, namely the central ear artery and its first generation of branch arteries: these are proximal "feed" vessels (150-700 microns internal diameter) in this bed. The findings are consistent with enhancement of EDRF release by the physical stimulus of shear stress in resistance vessels as previously demonstrated in conduit vessels-a phenomenon which is likely to exert a major influence on flow in vascular networks. EDRF activity thus reduced perfusion pressure and power losses, particularly in highly constricted preparations. Shear-induced release of EDRF may provide an integrating link between flow and arterial topography by optimizing perfusion characteristics over a wide range of flow rates.

Microangiographic investigation of the effects of radiographic contrast media and hyperkalaemia on coronary artery calibre in the rabbit

A microangiographic technique, using novel methods of contact X-ray microscopy, was developed and used to study the effects of ionic (Urografin 370) and non-ionic (Omnipaque 350) radiographic contrast media, and hyperkalaemia (exposure to 15, 30 and 60 mM-K+ solutions) on coronary artery calibre and total coronary vascular resistance in isolated, Langendorff-perfused rabbit hearts. Repeated injection of both types of contrast media produced similar haemodynamic effects and some reduction in coronary diameter, but greater variation in arterial calibre was observed with Urografin (P less than 0.001). Perfusion with hyperkalaemic solutions produced a dose-related increase in total coronary vascular resistance (P less than 0.001), but this was associated with a complex pattern of changes in large-vessel calibre. The direction and magnitude of the responses to hyperkalaemia varied depending on the site within the artery studied; in general hyperkalaemia produced a dose-related vasoconstriction which was greater distally than proximally. Thus, with 15 mM-K+ vasoconstriction occurred in the left anterior descending artery (4.3% proximally; 15.6% distally) which increased to 40.7 and 52.1% (proximally and distally, respectively) with 30 mM-K+. With 60 mM-K+ further diffuse and segmental vasoconstriction occurred in 4/5 and 1/5 hearts respectively (mean values 31.5 and 56.7% at the proximal and distal sites). During perfusion with 15 mM-K+, net vasodilatation (17% at both the proximal and distal sites) was noted in the left ventricular branch of the circumflex artery, but with 30 mM-K+ vasoconstriction (18.3% proximally and 38.0% distally) occurred. Thus, while hyperkalaemia consistently increased coronary vascular resistance, these changes were associated with marked variation in the extent and distribution of in situ constriction and dilatation within the coronary circulation.

Transfection of a human cytochrome P-450 gene into the human lymphoblastoid cell line, AHH-1, and use of the recombinant cell line in gene mutation assays

We have demonstrated that the human cytochrome P1-450 gene can be transfected into the AHH-1 human lymphoblastoid cell line using the pHEBo vector and hygromycin selection. The transfected gene was expressed when regulatory sequences derived from the herpes simplex virus thymidine kinase gene were incorporated in appropriate orientations. Gene expression was monitored at the enzyme level using assays for 7-ethoxyresorufin deethylase, 7-ethoxycoumarin deethylase and benzo[a]pyrene hydroxylase activities. Bulk transformed cell populations had 2- to 3-fold more of these enzyme activities compared with control populations. Subclones of the bulk population expressing still higher levels of 7-ethoxyresorufin deethylase activity were also obtained. Expression of the transfected cytochrome P1-450 gene was stable for 20-30 days in the presence of hygromycin B. The transformed cell populations were found to be suitable for use in gene locus mutation assays and the mutagenicity of aflatoxin-B1 and 2-acetylaminofluorene (AAF) were examined. Aflatoxin-B1 was found to be 2-3 times more mutagenic to cells bearing the transfected cytochrome P1-450 activity as compared with control cells. In contrast, no difference in AAF mutagenicity was observed. Analysis of the AAF metabolite profile indicated that cells expressing the transfected cytochrome P1-450 gene produced 8-fold more N- and 7-hydroxy-AAF than control cells. The similarity in mutagenic responses between control cells and cells bearing the transfected cytochrome P1-450 gene may be due to the low deacetylase activity of AHH-1 cells. These observations indicate that this vector and expression system are suitable for introducing novel metabolic activities into the AHH-1 cell line.

An evaluation of biological and conventional pig selection indices

Two biological and 4 conventional pig selection indices were compared. The biological indices were lean meat growth (LGRTH) and lean meat feed conversion (LFCR). The conventional indices included average daily gain (ADG) and back fat measured at the P2 site (FP2) as criteria (index OF), or as in OF but with the addition of feed conversion ratio (FCR) as a selection criterion (index BTS). Also, using the same criteria as in BTS and OF, restricted indices were derived setting the genetic change in FP2 at zero (indices BTS.FP2 and OF.FP2). The correlated response in average daily feed intake (ADI) was calculated for all indices. The application of all indices resulted in variable, but desirable, predicted genetic changes in ADG, FCR and FP2. The correlated response in AD1 was positive, except for BTS and LFCR, where it was zero and negative, respectively. The correlations among all indices were high (r > 0.7) except for those restricting FP2. It is concluded that conventional selection indices have advantages over biological indices because they more easily enable the monitoring of changes in the components of overall merit and updating of breeding objectives.

X-ray microscopy of the prostate gland

A technique is described for investigating the internal structure of the prostate gland (including calcification) by projection X-ray microscopy (microradiography). The results show that the technique can be used in conjunction with the corresponding histological preparations to complement the examination of the prostate gland by demonstrating tissue density and the structure and location of microcalcification less than 5 microns in diameter.

Endothelium-derived relaxing factor (EDRF) and resistance vessels in an intact vascular bed: a microangiographic study of the rabbit isolated ear

1. Microradiographic techniques have been used to show that endothelium-derived relaxing factor (EDRF), which is believed to be nitric oxide, influences vasomotor responses in small arteries and arterioles down to 25 micron in diameter in an isolated, intact, buffer-perfused ear preparation of the rabbit. Arteries down to 75 micron in diameter, i.e. the central ear artery (G0) and its first three generations of branch vessels (G1, G2 and G3) were studied quantitatively. 2. Relative constrictor responses to 1 micron 5-hydroxytryptamine (5-HT) and the combination of 1 microM 5-HT and 1 microM histamine diminished progressively from G0 to G3. Constrictor responses to 5-HT were doubled in all generations by 1 microM haemoglobin which abolishes EDRF activity. 3. Relative dilator responses to acetylcholine or to substance P in preconstricted arteries were, in contrast, equal in the different generations. Mean -log (IC50) values calculated from diameter measurements were 7.63 +/- 0.10 M and 9.80 +/- 0.11 M, respectively. These dilator responses were abolished by 1 microM haemoglobin, implying that they were EDRF-mediated. Spatial homogeneity of relative dilator responses was found also with glyceryl trinitrate (10 or 50 microM) whose activity is thought to depend on biotransformation to nitric oxide, in both the presence and the absence of haemoglobin. 4. This finding of spatial homogeneity of the diameter response to changes in EDRF activity (or to glyceryl trinitrate) implies that EDRF influences hydrodynamic resistance more in vessels where constrictor tone is high.

EDRF coordinates the behaviour of vascular resistance vessels

Constriction of vascular smooth muscle in response to the stimulus of raised intravascular pressure--the myogenic response--represents a positive feedback mechanism which, if unopposed, could theoretically lead to instability in the intact circulation. Dilation in response to increased intraluminal flow would provide an opposing feedback mechanism which could confer overall stability. Flow-dependent dilation in conduit vessels is mediated by endothelium-derived relaxing factor (EDRF), but the relationship between flow and EDRF activity has not been studied in resistance vessels in situ. We here demonstrate that EDRF can coordinate the aggregate hydrodynamic properties of an intact network. Under control conditions, EDRF maintains a fourth-power relationship between diameter and flow so that the pressure gradient in each vessel asymptotically approaches a constant value at high flow rates. Basal EDRF release may also maintain a similar spatial distribution of flow at different flow rates, even under conditions of moderate pharmacological constriction.