Lumbopelvic fixation in the treatment of spinopelvic dissociation: union, complications, and neurologic outcomes of a multicenter case series

PURPOSE

To review outcomes of spinopelvic dissociation treated with open lumbopelvic fixation.

METHODS

We reviewed all cases of spinopelvic dissociation treated at three Level-I trauma centers with open lumbopelvic fixation, including those with adjunctive percutaneous fixation. We collected demographic data, associated injuries, pre- and postoperative neurologic status, pre- and postoperative kyphosis, and Roy-Camille classification. Outcomes included presence of union, reoperation rates, and complications involving hardware or wound.

RESULTS

From an initial cohort of 260 patients with spinopelvic dissociation, forty patients fulfilled inclusion criteria with a median follow-up of 351 days. Ten patients (25%) had a combination of percutaneous iliosacral and open lumbopelvic repair. Average pre- and postoperative kyphosis was 30 degrees and 26 degrees, respectively. Twenty patients (50%) had neurologic deficit preoperatively, and eight (20%) were unknown or unable to be assessed. All patients presenting with bowel or bladder dysfunction (n = 12) underwent laminectomy at time of surgery, with 3 patients (25%) having continued dysfunction at final follow-up. Surgical site infection occurred in four cases (10%) and wound complications in two (5%). All cases (100%) went on to union and five patients (13%) required hardware removal.

CONCLUSION

Open lumbopelvic fixation resulted in a high union rate in the treatment of spinopelvic dissociation. Approximately 1 in 6 patients had a wound complication, the majority of which were surgical site infections. Bowel and bladder dysfunction at presentation were common with the majority of cases resolving by final follow-up when spinopelvic dissociation had been treated with decompression and stable fixation.

Spontaneous Unilateral Chiari I Secondary to Acquired Tonsillar Hypertrophy/Pseudomass With Syringomyelia in a Juvenile With Progressive Scoliosis

Chiari type 1 malformation (CM-1) is a structural defect of the central nervous system in which part of the cerebellar tonsils descend below the level of the foramen magnum, sometimes with associated syringomyelia. Although Chiari malformations were traditionally believed to be congenital, several cases of acquired CM-1 with syringomyelia have been reported. Usually associated with repeat lumbar puncture, increased intracranial pressure, and craniocephalic disproportion, CM-1 in the absence of an underlying etiology is rare. We report a rare case of spontaneous idiopathic tonsillar hypertrophy causing unilateral CM-1 with syringomyelia associated with progressive scoliosis in a juvenile with a previously normal neonatal MRI brain and no known underlying pathology. A 9-year-old boy was found to have scoliosis at a routine well-child visit with progression indicated on radiographs 4 months later. Whole spine MRI was performed and showed a new CM-1 with globular, mass-like configuration of the descended right tonsil with otherwise normal tonsillar characteristics. Surgical decompression via suboccipital craniectomy and C1 laminectomy with duraplasty was performed with improvement illustrated on repeat MRI 3 months postoperatively. This rare case emphasizes the importance of routine MRI spine early in select patients with idiopathic scoliosis and illustrates the favorable outcomes noted after decompressive craniectomy.

Non-osseous considerations in diagnostic imaging for pelvic and acetabular trauma

High-quality imaging is crucial for orthopedic traumatologists in the evaluation and management of pelvic and acetabular fractures. Computed tomography (CT) plays an essential role in the diagnosis and treatment of patients with these complex injuries. A thoughtful evaluation of associated soft tissues can reveal additional details about the patient and their injury that may impact treatment. This review aims to highlight soft tissue findings that should be identified when evaluating the initial diagnostic imaging after pelvic and acetabular trauma.

Neurologic injury after spinopelvic dissociation: Incidence, outcome, and predictors

BACKGROUND

Traumatic spinopelvic dissociation is a rare injury pattern resulting in discontinuity between the spine and bony pelvis. This injury is associated with a known risk of neurologic compromise which can impact the clinical outcome of these patients. We sought to determine incidence and characteristics of neurologic injury, outcomes following treatment, and predictive factors for neurologic recovery.

METHODS

We reviewed the clinical documentation and imaging of 270 patients with spinopelvic dissociation from three Level-1 trauma centers treated over a 20-year period. From this cohort, 137 patients fulfilled inclusion criteria with appropriate follow-up. Details surrounding patient presentation, incidence of neurologic injury, and outcome variables were collected for each injury. Neurologic injuries were categorized using the Gibbons criteria. Multivariate analysis was performed to assess for patient and injury factors predictive of neurologic injury and recovery.

RESULTS

The overall incidence of neurologic injury in spinopelvic dissociation injuries was 33% (45/137), with bowel and/or bladder dysfunction (n=16) being the most common presentation. Complete neurologic recovery was seen in 26 cases (58%) and two patients (4%) improved at least one Gibbon stage in clinical follow-up. The most common long-term neurologic sequela at final follow-up was radiculopathy (n=12, 9%). Increased kyphosis was found to be associated with neurologic injury (p=0.002), while location of transverse limb and Roy-Camille type were not predictive of neurologic injury (p=0.31 and p=0.07, respectively). There were no factors found to be predictive of neurologic recovery in this cohort.

CONCLUSION

Neurologic injury is commonly seen in patients with spinopelvic dissociation and complete neurologic recovery was seen in the majority of patients at final follow-up. When present, long term neurologic dysfunction is most commonly characterized by radiculopathy. While increasing kyphosis was shown to be associated with neurologic injury, no patient or injury factors were predictive of neurologic recovery.

Development and validation of a gene expression test to identify hard-to-heal chronic venous leg ulcers

Background

Chronic venous leg ulcers pose a significant burden to healthcare systems, and predicting wound healing is challenging. The aim of this study was to develop a genetic test to evaluate the propensity of a chronic ulcer to heal.

Methods

Sequential refinement and testing of a gene expression signature was conducted using three distinct cohorts of human wound tissue. The expression of candidate genes was screened using a cohort of acute and chronic wound tissue and normal skin with quantitative transcript analysis. Genes showing significant expression differences were combined and examined, using receiver operating characteristic (ROC) curve analysis, in a controlled prospective study of patients with venous leg ulcers. A refined gene signature was evaluated using a prospective, blinded study of consecutive patients with venous ulcers.

Results

The initial gene signature, comprising 25 genes, could identify the outcome (healing versus non-healing) of chronic venous leg ulcers (area under the curve (AUC) 0·84, 95 per cent c.i. 0·73 to 0·94). Subsequent refinement resulted in a final 14-gene signature (WD14), which performed equally well (AUC 0·88, 0·80 to 0·97). When examined in a prospective blinded study, the WD14 signature could also identify wounds likely to demonstrate signs of healing (AUC 0·73, 0·62 to 0·84).

Conclusion

A gene signature can identify people with chronic venous leg ulcers that are unlikely to heal.

Animal physiology and genetic aspects of ryegrass staggers in grazing sheep

Ryegrass staggers (RGS) is a metabolic disease of herbivores, caused by the ingestion of perennial ryegrass (Lolium perenne L.) containing a fungal endophyte (Neotyphodium lolii) which produces a tremorgenic toxin, lolitrem B. RGS has a major economic impact for agriculture in New Zealand as well as internationally. Management of RGS in grazing sheep can be problematic, and there is an incomplete knowledge of the interaction between the toxin and the grazing animal. This review is focused on recent advances in understanding the molecular physiology of RGS in the affected animal as well as the influence of animal genetics on the degree of susceptibility to RGS. Investigations to date suggest that the primary target for toxin is the large conductance, calcium-activated, potassium (BK) channel, resulting in disruption of neuromuscular junction signalling. Genetic investigation has established the existence of genes influencing resistance to RGS, however their identity has not been confirmed and their impact has not been established. Studies to date suggest that a multi-gene selection approach will be necessary in order to develop an effective selection tool for use in the agricultural industries.

Reversal of neurobehavioral social deficits in dystrophic mice using inhibitors of phosphodiesterases PDE5A and PDE9A

Duchenne muscular dystrophy is caused by mutations in the DYSTROPHIN gene. Although primarily associated with muscle wasting, a significant portion of patients (approximately 25%) are also diagnosed with autism spectrum disorder. We describe social behavioral deficits in dystrophin-deficient mice and present evidence of cerebellar deficits in cGMP production. We demonstrate therapeutic potential for selective inhibitors of the cGMP-specific PDE5A and PDE9A enzymes to restore social behaviors in dystrophin-deficient mice.

The effects of age, weight, and sire on pregnancy rate in cattle

The goal was to estimate the heritabilities and genetic variances for pregnancy rate (PR) and calving date (CD) in Angus cattle along with the effect of weight, age, and sire on PR and CD. The data consisted of 4,999 records on PR and CD. Statistical models included year as a fixed effect; premating/postmating weight and age as covariates; and sire of embryo, maternal grandsire (MGS), and permanent maternal environmental effects as random effects. The models also included the interactions between herd and weight (weight change). Direct and maternal effects on PR and CD were estimated using sire MGS and animal models in REML. Pregnancy rate increased from age 2 to 6 and decreased from age 7 to 11 (P < 0.01) and this effect was independent of the culling strategy. There was a quadratic effect of premating cow weight independent of age on PR, with lower PR for low weights (P < 0.01). Overall, cows with a premating weight of 550 kg had the greatest PR. Cows that lost weight during mating had lower PR (P < 0.01). The maternal additive heritability for PR was 0.001 ± 0.012 and the direct additive heritability was 0.024 ± 0.020. The ratio of permanent maternal environmental variance to phenotypic variance was significant (0.048 ± 0.017; P < 0.01). This demonstrates that permanent maternal environmental effects play a major role in the repeatability of PR (0.049 ± 0.015; P < 0.01). The maternal additive heritability for CD was 0.040 ± 0.022, and the direct additive heritability was 0.076 ± 0.045. The ratio of permanent maternal environmental variance to phenotypic variance was low (0.014 ± 0.017) and the repeatability for CD was significant (0.0544 ± 0.0180; P < 0.01). This suggests that maternal genetic effects are as important as direct genetic effects on CD. There was a positive quadratic relationship between premating cow weight and CD with delayed calving for low/high weights (P < 0.01). Cows that lost weight over mating also had a later CD (P < 0.01). Comparisons of a weight-selected herd to the control herd showed differences (P < 0.05) in the optimal premating weight for early calving (control, 480 kg, and weight selected, 615 kg). Calving date was also more sensitive to changes in weight over mating in the weight selection herd (P < 0.05). Therefore, the set point in the weight-fertility axis and the sensitivity of fertility to changes in weight both changed in the weight selection herd.

Intracellular localization and induction of a dynamic RNA-editing event of macro-algal V-ATPase subunit A (VHA-A) in response to copper

A V-ATPase subunit A protein (VHA-A) transcript together with a variant (C793 to U), which introduces a stop codon truncating the subunit immediately downstream of its ATP binding site, was identified within a Fucus vesiculosus cDNA from a heavy metal contaminated site. This is intriguing because the VHA-A subunit is the crucial catalytic subunit responsible for the hydrolysis of ATP that drives ion transport underlying heavy metal detoxification pathways. We employed a chemiluminescent hybridization protection assay to quantify the proportion of both variants directly from mRNA while performing quantification of total transcript using Q-PCR. Polyclonal antisera raised against recombinant VHA-A facilitated simultaneous detection of parent and truncated VHA-A and revealed its cellular and subcellular localization. By exploiting laboratory exposures and samples from an environmental copper gradient, we showed that total VHA-A transcript and protein, together with levels of the truncated variant, were induced by copper. The absence of a genomic sequence representing the truncated variant suggests a RNA editing event causing the production of the truncated VHA-A. Based on these observations, we propose RNA editing as a novel molecular process underpinning VHA trafficking and intracellular sequestration of heavy metals under stress.

Intracranial arteries in individuals with the elastin gene hemideletion of Williams syndrome

BACKGROUND AND PURPOSE

Williams syndrome, a rare genetic disorder with a striking neurobehavioral profile characterized by extreme sociability and impaired visuospatial construction abilities, is caused by a hemideletion that includes the elastin gene, resulting in frequent supravavular aortic stenosis and other stenotic arterial lesions. Strokes have been reported in Williams syndrome. Although the extracranial carotid artery has been studied in a sample of patients with Williams syndrome, proximal intracranial arteries have not.

MATERIALS AND METHODS

Using MRA, we studied the intracranial vessels in 27 participants: 14 patients with Williams syndrome (age range, 18-44 years; mean age, 27.3 ± 9.1; 43% women) and 13 healthy control participants with similar age and sex distribution (age range, 22-52 years; mean age, 33.4 ± 7.6; 46% women). All participants with Williams syndrome had hemideletions of the elastin gene. Blinded to group allocation or to any other clinical data, a neuroradiologist determined the presence of intracranial vascular changes in the 2 groups.

RESULTS

The Williams syndrome group and the healthy control group had similar patency of the proximal intracranial arteries, including the internal carotid and vertebral arteries; basilar artery; and stem and proximal branches of the anterior cerebral artery, MCA, and posterior cerebral arteries. The postcommunicating segment of the anterior cerebral artery was longer in the Williams syndrome group.

CONCLUSIONS

Despite the elastin haploinsufficiency, the proximal intracranial arteries in Williams syndrome preserve normal patency.

Quantitative trait loci for organ weights and adipose fat composition in Jersey and Limousin back-cross cattle finished on pasture or feedlot

A QTL study of live animal and carcass traits in beef cattle was carried out in New Zealand and Australia. Back-cross calves (385 heifers and 398 steers) were generated, with Jersey and Limousin backgrounds. This paper reports on weights of eight organs (heart, liver, lungs, kidneys, spleen, gastro-intestinal tract, fat, and rumen contents) and 12 fat composition traits (fatty acid (FA) percentages, saturated and monounsaturated FA subtotals, and fat melting point). The New Zealand cattle were reared and finished on pasture, whilst Australian cattle were reared on grass and finished on grain for at least 180 days. For organ weights and fat composition traits, 10 and 12 significant QTL locations (P<0.05), respectively, were detected on a genome-wide basis, in combined-sire or within-sire analyses. Seven QTL significant for organ weights were found at the proximal end of chromosome 2. This chromosome carries a variant myostatin allele (F94L), segregating from the Limousin ancestry, and this is a positional candidate for the QTL. Ten significant QTL for fat composition were found on chromosomes 19 and 26. Fatty acid synthase and stearoyl-CoA desaturase (SCD1), respectively, are positional candidate genes for these QTL. Two FA QTL found to be common to sire groups in both populations were for percentages of C14:0 and C14:1 (relative to all FAs) on chromosome 26, near the SCD1 candidate gene.

Genetic mapping of quantitative trait loci for meat quality and muscle metabolic traits in cattle

A whole-genome scan was carried out in New Zealand and Australia to detect quantitative trait loci (QTL) for live animal and carcass composition traits and meat quality attributes in cattle. Backcross calves (385 heifers and 398 steers) were generated, with Jersey and Limousin backgrounds. The New Zealand cattle were reared and finished on pasture, whilst Australian cattle were reared on grass and finished on grain for at least 180 days. This paper reports on meat quality traits (tenderness measured as shear force at 4-5 ages on two muscles as well as associated traits of meat colour, pH and cooking loss) and a number of metabolic traits. For meat quality traits, 18 significant QTL (P < 0.05), located in nine linkage groups, were detected on a genome-wise basis, in combined-sire (seven QTL) or within-sire analyses (11 QTL). For metabolic traits, 11 significant QTL (P < 0.05), located in eight linkage groups, were detected on a genome-wise basis, in combined-sire (five QTL) or within-sire analyses (six QTL). BTA2 and BTA3 had QTL for both metabolic traits and meat quality traits. Six significant QTL for meat quality and metabolic traits were found at the proximal end of chromosome 2. BTA2 and BTA29 were the most common chromosomes harbouring QTL for meat quality traits; QTL for improved tenderness were associated with Limousin-derived and Jersey-derived alleles on these two chromosomes, respectively.

Relationship between sporidesmin-induced liver injury and serum activity of gamma-glutamyltransferase in Romney lambs sired by facial eczema-resistant or control rams

AIM

To test whether long-term selection for resistance to facial eczema (FE) influences the relationship between liver injury score (LIS) and serum activity of gamma-glutamyltransferase (GGT) in sporidesmin-dosed sheep.

METHODS

Two groups of Romney lambs were generated for this study in 1999, out of an unselected group of ewes and sired by either selected FE-resistant (R) line (n=74 lambs) or unselected Control (C) line (n=119 lambs) rams from the Ruakura Research Centre long-term FE-selection experiment. The lambs were given a single oral dose of sporidesmin, sampled for determination of serum GGT activity 3 weeks later, and lambs that had serum GGT activity >55 IU/l (reactors) were humanely killed and assessed for LIS post mortem, 6 weeks after dosing. A second round of dosing was applied to the nonreactors, followed as above by analysis of serum GGT activity and assessment of LIS post mortem (both reactors and nonreactors).

RESULTS

There was a significant linear relationship between LIS and logeGGT, which did not differ between the 2 sire lines (LIS= -2.96 (SE 0.38) + 0.89 (SE 0.07) x loge GGT, R2=0.54, p<0.001).

CONCLUSIONS

Serum GGT is a valid indicator of LIS in lambs by sires selected for different levels of susceptibility to FE. The logeGGT-LIS relationship has not changed as a result of genetic selection for resistance to FE.

The relationship between estimates of ovarian size in live cattle and subsequent measurementspost mortem

The reproductive tract of each of 122 cows was palpated transrectally by a veterinarian on the day before they were slaughtered, to obtain estimates of ovarian size and to identify palpable ovarian structures. Reproductive tracts were then retrieved post mortem. Ovarian volumes were recorded and compared with in vivo size scores (coded 1-5; 1 being the smallest). Ovarian volumes averaged 4.0 ml (score 1), 7.0 ml (2), 10.0 ml (3), 12.9 ml (4) and 15.9 ml (5). There was a linear increase in ovarian volume of 3.0 +/- 0.1 ml per score unit (r2 = 0.792). The curvilinear regression included a significant quadratic term (p<0.05), but only accounted proportionally for an additional 0.003 of the sums of squares. Ovarian size score was about proportional to volume and could be used as a non-surgical technique to measure ovarian volume in live cattle.

Bowman-Birk inhibitor attenuates dystrophic pathology in mdx mice

Bowman-Birk inhibitor concentrate (BBIC), a serine protease inhibitor, has been shown to diminish disuse atrophy of skeletal muscle. Duchenne muscular dystrophy (DMD) results from a loss of dystrophin protein and involves an ongoing inflammatory response, with matrix remodeling and activation of transforming growth factor (TGF)-β(1) leading to tissue fibrosis. Inflammatory-mediated increases in extracellular protease activity may drive much of this pathological tissue remodeling. Hence, we evaluated the ability of BBIC, an extracellular serine protease inhibitor, to impact pathology in the mouse model of DMD (mdx mouse). Mdx mice fed 1% BBIC in their diet had increased skeletal muscle mass and tetanic force and improved muscle integrity (less Evans blue dye uptake). Importantly, mdx mice treated with BBIC were less susceptible to contraction-induced injury. Changes consistent with decreased degeneration/regeneration, as well as reduced TGF-β(1) and fibrosis, were observed in the BBIC-treated mdx mice. While Akt signaling was unchanged, myostatin activitation and Smad signaling were reduced. Given that BBIC treatment increases mass and strength, while decreasing fibrosis in skeletal muscles of the mdx mouse, it should be evaluated as a possible therapeutic to slow the progression of disease in human DMD patients.

Genetic variation in the beta, beta-carotene-9', 10'-dioxygenase gene and association with fat colour in bovine adipose tissue and milk

beta, beta-carotene-9', 10'-dioxygenase (BCO2) plays a role in cleaving beta-carotene eccentrically, and may be involved in the control of adipose and milk colour in cattle. The bovine BCO2 gene was sequenced as a potential candidate gene for a beef fat colour QTL on chromosome (BTA) 15. A single nucleotide base change located in exon 3 causes the substitution of a stop codon (encoded by the A allele) for tryptophan(80) (encoded by the G allele) (c. 240G>A, p.Trp80stop, referred to herein as SNP W80X). Association analysis showed significant differences in subcutaneous fat colour and beta-carotene concentration amongst cattle with different BCO2 genotypes. Animals with the BCO2 AA genotype had more yellow beef fat and a higher beta-carotene concentration in adipose tissues than those with the GA or GG genotype. QTL mapping analysis with the BCO2 SNP W80X fitted as a fixed effect confirmed that this SNP is likely to represent the quantitative trait nucleotide (QTN) for the fat colour-related traits on BTA 15. Moreover, animals with the AA genotype had yellower milk colour and a higher concentration of beta-carotene in the milk.

A genome-screen experiment to detect quantitative trait loci affecting resistance to facial eczema disease in sheep

Facial eczema (FE) is a secondary photosensitization disease arising from liver cirrhosis caused by the mycotoxin sporidesmin. The disease affects sheep, cattle, deer and goats, and costs the New Zealand sheep industry alone an estimated NZ$63M annually. A long-term sustainable solution to this century-old FE problem is to breed for disease-resistant animals by marker-assisted selection. As a step towards finding a diagnostic DNA test for FE sensitivity, we have conducted a genome-scan experiment to screen for quantitative trait loci (QTL) affecting this trait in Romney sheep. Four F(1) sires, obtained from reciprocal matings of FE resistant and susceptible selection-line animals, were used to generate four outcross families. The resulting half-sib progeny were artificially challenged with sporidesmin to phenotype their FE traits measured in terms of their serum levels of liver-specific enzymes, namely gamma-glutamyl transferase and glutamate dehydrogenase. In a primary screen using selective genotyping on extreme progeny of each family, a total of 244 DNA markers uniformly distributed over all 26 ovine autosomes (with an autosomal genome coverage of 79-91%) were tested for linkage to the FE traits. Data were analysed using Haley-Knott regression. The primary screen detected one significant and one suggestive QTL on chromosomes 3 and 8 respectively. Both the significant and suggestive QTL were followed up in a secondary screen where all progeny were genotyped and analysed; the QTL on chromosome 3 was significant in this analysis.

Variation in bull beef quality due to ultimate muscle pH is correlated to endopeptidase and small heat shock protein levels

This study set out to determine if ultimate pH (pH(u)) affected the performance of intracellular small heat shock protein and endopeptidase dynamics in muscle during beef ageing. Longissimus dorsi muscles from 39 Angus or Limousin×Angus bulls were examined to see if pH(u) achieved at 22h post mortem (rigor) affected tenderness and water holding capacity of beef. Samples were segregated into three pH(u) groups termed high (pH>6.3), intermediate (5.7<pH<6.3) and low (pH<5.7) pH(u) beef. More than 30% of bull beef did not achieve acceptable tenderness at 8 days post mortem with this ageing regime. No significant differences in calpain or cathepsin enzyme levels due to meat pH were observed until after 22h post mortem, but low pH(u) beef had elevated caspase 3/7 activity soon after slaughter. At 22h post mortem, greater levels of μ-calpain enzyme were found in the high and intermediate pH(u) beef and cathepsin B levels were superior in the low pH(u) beef after 2 days post mortem. Different rates of desmin and troponin T protein degradation were also observed in aged bull beef. Both proteins were degraded within 6h post mortem for high pH(u) beef, but took >3 days post mortem for intermediate pH(u) beef. High levels of alpha β-crystallin (aβC) at 22h post mortem coincided with delayed muscle protein degradation for low pH(u) beef. Our results support the hypothesis that aβC shields myofibrils and buffers against endopeptidase degradation of beef structure during ageing.

Effects of the myostatin F94L substitution on beef traits

This study investigated the effects of a SNP in the myostatin gene (MSTN or growth differentiation factor 8, GDF8) on birth, growth, carcass, and beef quality traits in Australia (Aust.) and New Zealand (NZ). The SNP is a cytosine to adenine transversion in exon 1, causing an amino acid substitution of leucine for phenylalanine(94) (F94L). The experiment used crosses between the Jersey and Limousin breeds, with the design being a backcross using first-cross bulls of Jersey x Limousin or Limousin x Jersey breeding, mated to Jersey and Limousin cows. Progeny were genotyped for the myostatin SNP and phenotyped in Aust., with finishing on feedlot (366 calves, over 3 birth years) and in NZ with finishing on pasture (416 calves, over 2 birth years). The effect of the F94L allele (A allele) on birth and growth traits was not significant. The F94L allele in Limousin backcross calves was associated with an increase in meat weight (7.3 and 5.9% of the trait mean in Aust. and NZ, respectively, P < 0.001), and a reduction in fat depth (-13.9 and -18.7% of the trait means on live calves (600 d) and carcasses, respectively, Aust. only, P < 0.001), intramuscular fat content (-8.2% of the trait mean in Aust., P < 0.05; -7.1% in NZ, not significant), total carcass fat weight (-16.5 and -8.1% of the trait mean, Aust. and NZ; P < 0.001 and P < 0.05, respectively). Meat tenderness, pH, and cooking loss of the M. longissimus dorsi were not affected by the F94L variant. In the Jersey backcross calves, additive and dominance effects were confounded because the F94L allele was not segregating in the Jersey dams. The combined effects, however, were significant on LM area (4.4% in both Aust., P < 0.05, and NZ, P < 0.01), channel fat (-11.7%, NZ only, P < 0.01), rib fat depth (-11.2%, NZ only, P < 0.05), and carcass fat weight (-7.1%, NZ only, P < 0.05). The results provide strong evidence that this myostatin F94L variant provides an intermediate and more useful phenotype than the more severe double-muscling phenotype caused by knockout mutations in the myostatin gene.

Heritability of resistance to infestation with the body louse, Bovicola ovis, in Romney sheep bred for differences in resistance or resilience to gastro-intestinal nematode parasites

The inheritance of resistance to louse infestation and the related allergic skin disease, cockle, was examined in Romney lambs. The lambs used in the study were the 2001- and 2004-born progeny of four experimental breeding lines ("Resistant", "Susceptible", "Resilient" and "Control") developed as part of a long-term study of the genetics of host resistance (maintenance of low faecal egg count (FEC) under nematode challenge) or resilience (maintenance of health and productivity under nematode challenge irrespective of FEC) to nematode parasites in sheep. Between 13 and 22 progeny (equally distributed between males and females, where possible) from each of five sires in each line were selected each year for this trial. All lambs (n=701) were examined for lice (Bovicola ovis) before artificial infestation; in 2001 the lambs were free of natural infestation, whilst in 2004 naturally acquired infestation was evident. In November 2001 and May 2002, approximately 60 B. ovis were transferred to each lamb, followed by monitoring at approximately 2-monthly intervals until August 2002. Similar procedures, but with fewer monitoring times, were repeated on the 2004 lambs. Overall, lambs in the Control line were significantly more susceptible to louse infestation and cockle compared with those in the other three lines (P<0.001). Least squares-means (SEM) of log-transformed louse score for the control, resistant, susceptible and resilient lines, respectively, were 2.178 (0.045), 1.499 (0.050), 1.618 (0.050) and 1.587 (0.044), and for cockle score were 1.36 (0.05), 0.76 (0.05), 0.95 (0.05) and 0.78 (0.05). From all progeny together, the heritability of log-transformed louse score was 0.22 (Standard Error (SE) 0.06) in autumn and 0.34 (SE 0.08) in winter, with a value of 0.44 (SE 0.09) when these data were combined. These estimates were similar to those obtained for resistance to gastro-intestinal nematodes in these breeding lines, using log-transformed FECs. Heritability estimates for cockle score in autumn, winter and when combined were 0.06 (SE 0.04), 0.45 (SE 0.09) and 0.40 (SE 0.09), respectively. The genetic correlations of mean log-transformed louse score with mean cockle score and levels of two different louse antigens in wool were, respectively, 0.97 (SE 0.04), 0.96 (SE 0.08) and 0.95 (SE 0.09). However, there was no significant genetic correlation between louse scores and FEC. These results suggest that selective breeding would be effective in reducing louse infestation and cockle in sheep, but that differences in louse burdens were not related to differences in nematode burdens as indicated by FECs.

Effect of myostatin F94L on carcass yield in cattle

In this study, a highly significant quantitative trait locus (QTL) for meat percentage, eye muscle area (EMA) and silverside percentage was found on cattle chromosome 2 at 0-15 cM, a region containing the positional candidate gene growth differentiation factor 8 (GDF8), which has the common alias myostatin (MSTN). Loss-of-function mutations in the MSTN gene are known to cause an extreme 'double muscling' phenotype in cattle. In this study, highly significant associations of MSTN with cattle carcass traits were found using maternally inherited MSTN haplotypes from outbred Limousin and Jersey cattle in a linkage disequilibrium analysis. A previously reported transversion in MSTN (AF320998.1:g.433C>A), resulting in the amino acid substitution of phenylalanine by leucine at position 94 of the protein sequence (F94L), was the only polymorphism consistently related to increased muscling. Overall, the size of the g.433C>A additive effect on carcass traits was moderately large, with the g.433A allele found to be associated with a 5.5% increase in silverside percentage and EMA and a 2.3% increase in total meat percentage relative to the g.433C allele. The phenotypic effects of the g.433A allele were partially recessive. This study provides strong evidence that a MSTN genotype can produce an intermediate, non-double muscling phenotype, which should be of significant value for beef cattle producers.

A review of genetic resistance to disease in Bos taurus cattle

Cattle show considerable variability in their responses to a wide range of disease challenges, and much of the variability is genetic. This review highlights genetic variation in disease susceptibility in Bos taurus cattle, with variation found at the breed level and also within breeds. Disease challenges come from bacteria and viruses, parasites and feed-borne toxins. For an animal to survive, it needs its own mechanisms for resisting these challenges, or for being resilient to them, or it must be protected artificially from them. Disease challenges have been classified as 'diseases from without', but there is also another class of genetic diseases resulting from inborn errors of metabolism, which might be called 'diseases from within'. Degrees of inheritance (heritabilities) are reviewed for a range of economically important traits including resistance to mastitis, ketosis, lameness, nematode parasites, external parasites, eye disease, respiratory disorders, tuberculosis, brucellosis, Johne's disease, foot-and-mouth disease, bovine spongiform encephalopathy, metabolic disorders caused by toxins found on the feed, and threshold levels of minerals and metabolites. Many, but not all, of the above require an immune response as part of the fight against an external challenge, and measurements have been made of general immune response as a way of describing or predicting how an animal will respond. There are now some examples of industry or breed societies applying selection for resistance to one or more diseases as part of a complete breeding objective in dairy cattle, beef cattle or dual purpose livestock. In most cases, industry and breed societies are in the early stages of applying effective selection pressure for resistance to specific cattle diseases, with the notable exceptions of Scandinavian cattle schemes, which lead the world in this respect.

The effect of Johne's disease on production traits in Romney, Merino and Merino x Romney-cross ewes

AIM

To quantify the effects of clinical Johne's disease on the performance of Romney, Merino and Merino x Romney-cross ewes.

METHODS

The performance of ewes was compared using eight birth cohorts (1971-1978). Merino and Merino-cross genotypes included New Zealand Merino and Australian Superfine Merino sources. Intensive monitoring of Johne's disease was undertaken over the production years 1975-1982. Positive diagnostic evidence of Johne's disease was established post mortem from lesions of granulomatous enteritis associated with high numbers of acid-fast bacilli. Over years, data on a total of 2,341 Romney ewes and 1,292 Merino and Merino x Romney-cross ewes were recorded, consisting of annual records of liveweight (LWT), greasy fleece weight (FWT), number of lambs born per ewe per year (NLB), and lifetime productivity of ewes.

RESULTS

A total of 82 (3.5%) Romney ewes and 62 (4.8%) Merino and Merino x Romney-cross ewes were diagnosed with clinical Johne's disease over the 8-year monitoring period, equivalent to 0.9% and 1.2% annual cases for these breeds, respectively, of the ewes present at mating. The percentage of clinical cases (p<0.04) and the age at death from Johne's disease (p<0.02) were lower for Romneys than for Superfine Merinos. The mean age of death from Johne's disease was 3.41 (standard error (SE) 0.06) years, lower than the mean disposal age from the flock of 5.03 (SE 0.02) years for clinically normal ewes (p<0.001). In their final year of production, ewes with clinical Johne's disease had lower LWT by 5.3 kg (10.5% of the mean; p<0.001), lower annual FWT by 0.54 (SE 0.10) kg (14.2%; p<0.001), fewer NLB by 0.15 (SE 0.07) lambs (13%; p<0.05), and lower litter weaning weights by 3.6 (SE 1.3) kg (15%; p<0.01) compared with clinically normal ewes. The size of the production losses associated with Johne's disease depended on the age to which ewes survived. Considering all production years of ewes (up to 8 years), the total weight of lambs weaned by ewes with clinical Johne's disease was 30.9 (SE 3.4) kg lower (46%; p<0.001) than the total from clinically normal ewes.

CONCLUSIONS

Clinical Johne's disease led to significant losses in LWT, FWT, NLB, and in the lifetime production of ewes, amounting overall to a 46% reduction in productivity (p<0.001).

CLINICAL RELEVANCE

Productivity losses from clinical cases of Johne's disease would be of considerable economic importance in flocks with a high incidence of the disease. The lack of good diagnostic tests for Johne's disease in the live animal, and the lack of active surveillance programmes, has made it difficult to establish the true prevalence of Johne's disease in sheep flocks in New Zealand, and its economic consequences.

Genotypic effects of calpain 1 and calpastatin on the tenderness of cooked M. longissimus dorsi steaks from Jersey x Limousin, Angus and Hereford-cross cattle

Single nucleotide polymorphisms (SNPs) in the calpain 1 (CAPN1) and calpastatin (CAST) genes were studied to determine their effects on meat tenderness in Bos taurus cattle. Strip loins (M. longissimus dorsi) were removed from cattle in four resource populations after slaughter (n = 1042), aged under controlled conditions until fixed times after rigor mortis, cooked and measured using a tenderometer. Animals were genotyped for the CAPN1 SNP c.947C>G (p.Ala316Gly; AF252504) and for the CAST SNP c.2959A>G (AF159246). Frequencies of CAPN1 C alleles ranged from 23% to 68%, and CAST A alleles from 84% to 99.5%. From all data combined, the CAPN1 CC genotype (compared with the GG genotype) was associated with a 20.1 +/- 1.7% reduced average shear force at intermediate stages of ageing (P < 0.001) and with a 9.5 +/- 1.3% reduction near ultimate tenderness (P < 0.001). The heterozygote was intermediate. For CAST, corresponding values for AA compared with AG genotypes were reductions of 8.6 +/- 2.0% and 5.1 +/- 1.6% respectively (both P < 0.001), but there were too few GG genotypes for comparison. There were small interactions between the CAPN1 and CAST genotypes. For the CAPN1 and CAST genotypes combined, the maximal genotype effect in average shear force was 25.7 +/- 5.5% (P < 0.001) at intermediate stages and 15.2 +/- 4.8% near ultimate tenderness (P < 0.01).

Marinobufagenin impairs first trimester cytotrophoblast differentiation

Preeclampsia is a pregnancy-specific syndrome that is the leading cause of maternal death during pregnancy in the developed world. In preeclampsia, a combination of immunological, genetic and environmental factors can lead to altered cytotrophoblast (CTB) invasion of the uterine wall, a process that is critical for normal placental development and pregnancy maintenance. Marinobufagenin (MBG) is an endogenous inhibitor of the sodium pump Na(+)/K(+) ATPase, and increased plasma MBG is associated with hypertension, chronic renal failure and preeclampsia. In the present study, the effects of MBG on CTB differentiation and invasion were investigated utilizing the first trimester extravillous CTB cell line SGHPL-4. MBG significantly inhibited SGHPL-4 proliferation in a dose-dependent manner. In addition, growth factor-induced migration and invasion were significantly inhibited by MBG treatment. These findings demonstrate that MBG impairs CTB differentiation along the invasive pathway. Elucidating the mechanisms by which MBG impairs placental development may increase our understanding of fetal and maternal pathologies associated with preeclampsia.

Human Cytomegalovirus-Induced Inhibition of Cytotrophoblast Invasion in a First Trimester Extravillous Cytotrophoblast Cell Line

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection in the United States and intrauterine transmission of HCMV occurs in approximately 40% of pregnant women with primary HCMV infection. Although HCMV infection during pregnancy clearly may be detrimental to fetal development, its consequences on placentation remain largely unexplored. In this study, the effects of HCMV infection on cytotrophoblast (CTB) invasion were investigated utilizing the first trimester extravillous CTB cell line SGHPL-4. HCMV infection significantly inhibited SGHPL-4 proliferation, epidermal growth factor (EGF)- and hepatocyte growth factor (HGF)-induced migration and invasion, as well as the secretion of matrix metalloproteinase (MMP)-2 and MMP-9. Both HCMV and EGF activated the EGF receptor (EGFR), inducing receptor tyrosine phosphorylation at specific residues. Of interest, EGFR was differentially activated by HCMV, and viral gene transcription was not required for the observed inhibitory effect on CTB invasiveness. These findings demonstrate that HCMV infection impairs CTB differentiation along the invasive pathway and that the differential regulation of EGFR by HCMV may contribute to impaired CTB function. Elucidating the mechanisms by which HCMV impairs placentation may be key in understanding fetal and maternal pathologies associated with intrauterine HCMV infection.

Three-dimensional growth of extravillous cytotrophoblasts promotes differentiation and invasion

Human trophoblast research relies on a combination of in vitro models, including isolated primary cultures, explant cultures, and trophoblast cell lines. In the present study, we have utilized the rotating wall vessel (RWV) bioreactor to generate a three-dimensional (3-D) model of human placentation for the study of cytotrophoblast (CTB) invasion. The RWV supported the growth of the human CTB cell line SGHPL-4 and allowed for the formation of complex, multilayered 3-D aggregates that were morphologically, phenotypically, and functionally distinct from SGHPL-4 monolayers. The cells cultured three-dimensionally differentiated into an aggressively invasive cell population characterized by the upregulation of matrix metalloproteinase-2 (MMP-2), MMP-3, MMP-9 and urokinase-type plasminogen activator (uPA) secretion and activation. Microarray analysis of the 3-D and 2-D cultured cells revealed increased expression in the 3-D cells of various genes that are known mediators of invasion, including MT1-MMP, PECAM-1 and L-selectin, as well as genes not previously associated with CTB differentiation such as MMP-13 and MT5-MMP. These results were verified by quantitative real-time PCR. These findings suggest that when cultured in 3-D, SGHPL-4 cells closely mimic differentiating in utero CTBs, providing a novel approach for the in vitro study of the molecular mechanisms that regulate CTB differentiation and invasion.

Breeding sheep in New Zealand that are less reliant on anthelmintics to maintain health and productivity

Breeding sheep that are less reliant on the use of anthelmintics to maintain acceptable health and productivity is one of several options that may assist farmers to manage the growing anthelmintic-resistance problem in New Zealand and meet consumer demands to minimise drug usage in livestock. Although it has been known for many years that genetic factors contribute to the ability of sheep to cope with roundworm challenge, attempts to selectively breed for such factors have occurred only recently. Two host traits, 'resistance' and 'resilience', are thought to be involved in limiting the deleterious effects of roundworms on the health and productivity of sheep, and the associated need for treatment with anthelmintics. Over the last decade, considerable advances have been made in our understanding of the feasibility and implications of breeding for these traits under practical conditions. The experimental breeding lines developed as part of this research are now proving to be a valuable resource for further work directed at identifying genes and/or genetic markers associated with host resistance and understanding the mechanisms of host immunity to nematode parasites in ruminants. This review provides an up-to-date summary of the results of research in this field, with particular reference to dual-purpose sheep in New Zealand, and describes how this information is being applied in practical breeding programmes.

Evaluation of a liquid formulation of monensin to control bloat in pasture-fed milking cows

AIM

To evaluate the effectiveness of a liquid formulation of monensin in reducing bloat score in milking cows grazing pasture.

METHODS

A Friesian x Jersey crossbred herd which had been genetically selected for high bloat susceptibility since 1973 was used in this study. Two trials were conducted, each involving two groups of 15 cows, randomly allocated to Treated or Control groups. Trial 1 involved twice-daily administration of a novel liquid formulation of monensin given to Treated cows at morning and afternoon milkings. Trial 2 involved once-daily administration of the same product to Treated cows at the morning milking only. Control cows received no preventative treatment. The total daily dose of monensin in each trial was 300 mg per cow, given in a total volume of 100 ml of liquid. Animals were scored for bloat twice-daily whilst grazing on white-clover/ryegrass or red-clover pastures. The scoring system used a scale of 0, 1, 1.5, 2, 2.5, or 3, representing scores of increasing bloat severity as assessed by palpation of abdominal pressure on the left and right sides of the cow.

RESULTS

In Trial 1, severe bloat was recorded at 9 out of 23 scoring sessions. Twelve Control cows required therapeutic treatment for bloat on at least one day, compared to 3 cows in the Treated group (p=0.003). In Trial 2, severe bloat in 3 of 9 scoring sessions led to 8/15 Control animals requiring therapeutic treatment compared to 1/14 cows in the Treated group (p=0.02).

CONCLUSIONS

Oral drenching with the liquid formulation of monensin tested was effective in reducing bloat score in milking cows grazed on pasture.

Three diagnostic signs in Williams syndrome

In a series of 48 patients with Williams syndrome examined from 1984 to 1988, 3 physical manifestations were noted which have not been emphasized in previous reports of this condition. Unusual sacral creases were found in 25/48 patients, a linear array of hemangiomas (nevus flammeus) on the back in 3/48, and limitation of supination in 5/48.

Hypothesis for development of a behavioral phenotype in Williams syndrome

We investigated the natural history of Williams syndrome (WS), including physical characteristics and cognitive, academic language, sensory integration, and adaptive and maladaptive behavior in 32 patients (age 3 to 30 years). These patients were available for psychoeducational testing, parent interview, medical and educational record review, and behavioral observation. Thirty-seven nonlocal individuals (age 8 months to 31 years) were not tested but data on history and development, sensory integration, adaptive and maladaptive behavior were collected resulting in a total sample of 69. The unique constellation of physical manifestations and associated clinical problems in WS contributes to a characteristic behavioral phenotype of 6 factors beginning in infancy with development of salient attachment behaviors. Later a key issue affecting the learning abilities of both the school-aged child and adult with WS was an inadequate development in the use of tools. Theoretical constructs from developmental behavioral genetics, attachment theory, operant conditioning, neuropsychology, and psychosocial theory considered interactively offer explanations for these characteristics.

Adults with Williams syndrome

Reports of adults with Williams syndrome (WS) have been rare. We have evaluated 13 adult WS patients and reviewed 16 case reports of WS in patients older than age 16 years. Adults in our study had progressive multisystem medical problems. Cardiovascular complications were common (12/13) including hypertension (8), supravalvular aortic stenosis (9), aortic hypoplasia (3), pulmonic artery stenosis (4), peripheral stenoses (3), and mitral valve prolapse (2). Joint limitation (12/13) was progressive, often accompanied by kyphoscoliosis and lordosis. Recurrent urinary tract infections in 6 individuals led to radiologic studies showing urethral stenosis in 2, and bladder diverticula and vesicoureteral reflux in 3. Gastrointestinal problems included obesity (5), chronic constipation (7), diverticulosis (3), and cholelithiasis (4). Hypercalcemia was documented in 5 patients, although others had hypercalcemic symptoms (abdominal pain, polyuria, and constipation). One 45-year-old man had parathyroid hyperplasia. Previous reports likewise document significant morbidity. Thus, Williams syndrome in an adult appears to dictate aggressive evaluation and monitoring. Investigation of calcium metabolism should be undertaken in each adult WS patient.

Inheritance of resistance to facial eczema: a review of research findings from sheep and cattle in New Zealand

Facial eczema (FE) is a costly problem to New Zealand pastoral agriculture, and has a detrimental impact on animal wellbeing. Incidence and severity of the disease can be reduced by grazing management and zinc prophylaxis. An additional strategy is to breed animals that are genetically resistant to intoxication with sporidesmin, the causative mycotoxin. This review summarises research findings on the inheritance of resistance of animals to FE, including evidence of among- and within-breed genetic variation, direct and correlated responses to selection, and identification of genetic markers and candidate genes for FE resistance.

Bovine parotid secretory protein: structure, expression and relatedness to other BPI (bactericidal/permeability-increasing protein)-like proteins

Members of the family of BPI (bactericidal/permeability-increasing protein)-like proteins are as yet incompletely characterized, particularly in cattle, where full-length sequence information is available for only three of the 13 family members known from other species. Structural bioinformatic analyses incorporating bovine homologues of several members of the BPI-like protein family, including two forms of bovine parotid secretory protein (PSP), showed that this family is also present in cattle. Expression analyses of several members of the BPI-like protein family in cattle, including PSP (Bsp30), von Ebner's minor salivary gland protein (VEMSGP) and lung-specific X protein (LUNX), showed a restricted pattern of expression, consistent with earlier hypotheses that these proteins function in the innate immune response to bacteria. The possible role of bovine PSP in susceptibility to pasture bloat in cattle is discussed.

Evaluation of single-nucleotide polymorphisms in CAPN1 for association with meat tenderness in cattle

Micromolar calcium activated neutral protease (CAPN1) was evaluated as a candidate gene for a quantitative trait locus (QTL) on BTA29 affecting meat tenderness by characterization of nucleotide sequence variation in the gene. Single-nucleotide polymorphisms (SNP) were identified by sequencing all 22 exons and 19 of the 21 introns in two sires (Piedmontese x Angus located at the U.S. Meat Animal Research Center in Clay Center, NE; Jersey x Limousin located at AgResearch in New Zealand) of independent resource populations previously shown to be segregating meat tenderness QTL on BTA29. The majority of the 38 SNP were found in introns or were synonymous substitutions in the coding regions, with two exceptions. Exons 14 and 9 contained SNP that were predicted to alter the protein sequence by the substitution of isoleucine for valine in Domain III of the protein, and alanine for glycine in Domain II of the protein. The resource populations were genotyped for these two SNP in addition to six intronic polymorphisms and two silent substitutions. Analysis of genotypes and shear force values in both populations revealed a difference between paternal CAPN1 alleles in which the allele encoding isoleucine at position 530 and glycine at position 316 associated with decreased meat tenderness (increased shear force values) relative to the allele encoding valine at position 530 and alanine at position 316 (P < 0.05). The association of maternal alleles with meat tenderness phenotypes is consistent with the hypothesis of CAPN1 as the gene underlying the QTL effect in two independent resource populations and presents the possibility of using these markers for selective breeding to reduce the numbers of animals with unfavorable meat tenderness traits.

Williams syndrome and related disorders

Three clinical conditions displaying phenotypic overlap have been linked to mutation or deletion of the elastin gene at 7q11.23. Supravalvar aortic stenosis, an autosomal dominant disorder characterized by elastin arteriopathy, is caused by mutation or intragenic deletions of ELN resulting in loss of function. Autosomal dominant cutis laxa, a primarily cutaneous condition, is the result of frameshift mutations at ELN that cause a dominant-negative effect on elastic fiber structure. Williams syndrome, a neurodevelopmental disorder is due to a 1.5 Mb deletion that includes ELN and at least 15 contiguous genes. The disorder is characterized by dysmorphic facies, mental retardation or learning difficulties, elastin arteriopathy, a unique cognitive profile of relative strength in auditory rote memory and language and extreme weakness in visuospatial constructive cognition, and a typical personality that includes overfriendliness, anxiety, and attention problems. The understanding of these disorders has progressed from phenotypic description to identification of causative mutations and insight into pathogenetic mechanisms for some aspects of the phenotype.

The subtle facial signs of prenatal exposure to alcohol: an anthropometric approach

OBJECTIVES

The purpose was to demonstrate that an objective, multivariate case definition of fetal alcohol syndrome (FAS) and partial fetal alcohol syndrome (PFAS) can be derived by means of craniofacial anthropometry.

STUDY DESIGN

Craniofacial measurements (n = 21) were taken of 100 individuals who had been exposed to alcohol before birth (41 FAS, 59 PFAS) and 31 members of a control group. Multivariate discriminant analysis was used to identify craniofacial measurements that best differentiated the 3 groups (FAS, PFAS, and control).

RESULTS

Both the FAS and PFAS groups had a unique craniofacial phenotype that could be accurately discriminated from that of the control group. Stepwise discriminant analysis identified 6 craniofacial measurements that could differentiate individuals with and without prenatal alcohol exposure with 96% accuracy, 98% sensitivity, and 90% specificity.

CONCLUSIONS

Individuals with FAS and PFAS have a distinctive facial phenotype that can be characterized anthropometrically. The phenotypic case definition could be used as a screening tool to identify individuals prenatally exposed to alcohol who do not exhibit a "classic" FAS phenotype but exhibit a more subtle craniofacial dysmorphia.

Modulation of contractile activation in skeletal muscle by a calcium-insensitive troponin C mutant

Calcium controls the level of muscle activation via interactions with the troponin complex. Replacement of the native, skeletal calcium-binding subunit of troponin, troponin C, with mixtures of functional cardiac and mutant cardiac troponin C insensitive to calcium and permanently inactive provides a novel method to alter the number of myosin cross-bridges capable of binding to the actin filament. Extraction of skeletal troponin C and replacement with functional and mutant cardiac troponin C were used to evaluate the relationship between the extent of thin filament activation (fractional calcium binding), isometric force, and the rate of force generation in muscle fibers independent of the calcium concentration. The experiments showed a direct, linear relationship between force and the number of cross-bridges attaching to the thin filament. Further, above 35% maximal isometric activation, following partial replacement with mixtures of cardiac and mutant troponin C, the rate of force generation was independent of the number of actin sites available for cross-bridge interaction at saturating calcium concentrations. This contrasts with the marked decrease in the rate of force generation when force was reduced by decreasing the calcium concentration. The results are consistent with hypotheses proposing that calcium controls the transition between weakly and strongly bound cross-bridge states.

Comprehensive linkage map of bovine chromosome 27

The results of genotypic data contributed to the International Society for Animal Genetics (ISAG) Bovine Chromosome 27 Workshop are presented. Eight laboratories contributed 23 261 informative meioses from 44 loci. Eighteen loci were typed by at least two laboratories and were used to construct a consensus linkage map. Twenty-one loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 66.9 cM. The sex-averaged comprehensive map was 75.5 cM, while the female and male maps were 73.1 and 63.7 cM, respectively. Five loci were excluded from the analysis because of ambiguous position in the linkage group and a low LOD score (less than 2.0). Average distance between loci in the comprehensive map was 1.98 cM.

Comprehensive linkage map of bovine chromosome 11

The results of genotypic data contributed to the International Society of Animal Genetics (ISAG) Bovine Chromosome 11 (BTA11) Workshop are presented. Six laboratories contributed a total of 26 199 informative meioses from 80 loci. Thirty-six loci were typed by at least two independent laboratories and were used to construct a consensus linkage map of the chromosome. The remaining loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 128.9 cM. The female consensus map was 101.2 cM, while the male consensus map was 129.8 cM. The comprehensive sex-averaged map was 134.2 cM and the average genetic distance between loci was 1.72 cM.

Complement activation by apoptotic endothelial cells following hypoxia/reoxygenation

Reperfusion of ischaemic tissue initiates an inflammatory reaction that increases tissue injury. Complement activation at the endothelium contributes to this inflammation. This study investigated the mechanism of complement activation following reoxygenation of hypoxic human umbilical vein endothelial cells (HUVEC) as a model for complement activation observed on endothelium in reperfused ischaemic tissue. HUVEC cultured in 1% oxygen followed by reoxygenation activated the classical complement pathway resulting in C3 deposition. There was an increase in apoptotic cells in these cultures that was demonstrated by binding of fluorescein isothiocyanate-Annexin V and staining for hypodiploid nuclei. To determine if apoptotic HUVEC activate complement, uniformly apoptotic cells were produced by serum and growth factor deprivation. These cells, but not the control HUVEC, activated the classical complement pathway in the absence of antibody or other serum factors. To determine if apoptotic cells in the reoxygenated cultures were activating complement, fluorescent analysis was done. Annexin V binding and C3d deposition on cells from reoxygenated cultures showed complete concordance on the subpopulation of apoptotic cells. In addition, complement activation following reoxygenation of HUVEC was eliminated by treatment of the cultures with a caspase inhibitor during reoxygenation. These results suggest that oxidative damage to endothelial cells during reoxygenation initiates apoptosis with exposure of phosphatidylserine. Apoptotic cells directly activate the classical pathway of complement by binding C1. Activation of complement at the endothelium may contribute to the inflammatory response as well as clearance and repair.

A possible dominant white gene in Jersey cattle

A white heifer ("Snow") was born in 1991 from coloured registered Jersey parents. She produced six calves sired by coloured Jersey bulls: three white bull calves, two white heifer calves, and one coloured bull calf. One of the white bull calves was mated with 40 Hereford x Friesian yearling heifers (white face, predominantly black body with some white patches). The 38 resulting calves included 16 white and 22 coloured calves. Twelve of the 16 white calves were heifers and four were bulls. Red or black spotting was recorded on some white calves. The results are consistent with an autosomal dominant mutant causing the white phenotype. The mutation appears to have arisen spontaneously in Snow, then passing to her white progeny and white grand-progeny. The white individuals varied from entirely white in a few cases, to most having some residual small areas of red or black pigmentation in patterns not typical of other reported white spotting patterns of cattle.

Bacterial populations on 30-night extended wear silicone hydrogel lenses

PURPOSE

Ocular infection and inflammation during hydrogel lens extended wear is often associated with colonization of the lenses with bacteria. This study compares colonization of a high Dk silicone hydrogel contact lens (lotrafilcon A) worn on a 30-night extended wear basis to a low Dk HEMA-based lens (etafilcon A) worn on a 6-night extended wear schedule.

METHODS

The group wearing the low Dk/t soft contact lens (n = 63) replaced their lenses weekly and the group wearing high Dk/t soft contact lenses replaced their lenses monthly (n = 64). Lens allocation was assigned randomly at enrollment. Worn lenses, from one eye only, were collected aseptically and placed in sterile vials. Microbial growth on various media was enumerated and the number of colony forming units (cfu) per lens was calculated in categories of normal ocular microbiota (such as coagulase-negative staphylococci and Propionibacterium spp.) and known ocular pathogens (such as Staphylococcus aureus and gram-negative bacteria). The proportion of samples colonized with these bacteria and the extent of colonization were compared between the two groups. The proportion of sterile lenses was calculated, and the types of bacteria on each lens group were compared.

RESULTS

No differences between the low and high Dk/t Soft contact lens groups were observed in the proportion of lenses colonized by Propionibacterium spp. (48% vs 43%, P = 0.4) or coagulase-negative staphylococci (47% vs 54%, P = 0.2). Similarly, no differences were found for lenses colonized by S. aureus (0% vs 2%, P = 0.1) or gram-negative bacteria (3% vs 2%, P = 0.8). The types of bacteria isolated from the high and low Dk/t lenses were similar. There were no differences in the number of sterile samples (28% vs 27%, P = 0.8) from each group.

CONCLUSIONS

These findings suggest that high Dk/t silicone hydrogel materials are colonized by similar numbers and types of microorganisms during extended wear compared to HEMA-based material. Most lenses were colonized by commensal bacteria during 30-night extended wear with high Dk/t lenses and during 6-night extended wear with low Dk/t lenses. The incidence of sterile samples was the same between the high and low Dk/t soft contact lens groups.

The Williams syndrome cognitive profile

Williams syndrome is a rare neurodevelopmental disorder caused by a hemizygous deletion of approximately 1.5 megabases on chromosome 7q11.23. In this article, we outline a Williams Syndrome Cognitive Profile (WSCP) that operationalizes the cognitive characteristics of the syndrome using measures of absolute and relative performance on subtests of the Differential Abilities Scales (Elliot, 1990a). Testing confirmed excellent sensitivity and specificity scores for the WSCP. Seventy-four of 84 individuals with Williams syndrome fit the WSCP while only 4 participants in a contrast group met all of the WSCP criteria. It was also found that the WSCP does not vary greatly with chronological age or overall level of cognitive ability for individuals with Williams syndrome. Possible applications for the WSCP include psychoeducational evaluation and empirical research such as the search for genotype/phenotype relations in this genetically based syndrome.

Sporidesmin-induced mortality and histological lesions in mouse lines divergently selected for response to toxins in endophyte-infected fescue

For eight generations, mouse lines were selected for smaller or larger reduction in postweaning gain from endophyte-infected fescue seed in the diet. After five generations in which there was no further selection for divergence in response to fescue toxicosis, the current experiment was conducted to determine whether resistant (R) and susceptible (S) lines differed in response to the mycotoxin sporidesmin (SPD). At approximately 8 wk of age, R and S mice that had never consumed endophyte-infected fescue seed were randomly assigned (five to seven per line x sex x SPD dose subclass) to receive dimethyl sulfoxide (DMSO) carrier or 10, 20, 30, or 40 mg/kg SPD by oral gavage. At death or euthanasia 14 d after treatment, livers and kidneys were collected for histological examination. Mice receiving 40 mg/kg SPD died sooner than mice receiving 30 mg/kg (63 vs 134 h; P = .02), but there was no line or line x dose interaction effect for time to death. Within those mice, neither line, dose, nor their interaction influenced liver weight or liver weight as a proportion of body weight. The R mice were more resistant to SPD than S mice; LD50 values were 23.6 and 31.8 mg/kg for the S and R lines, respectively (P < .05). Sporidesmin caused dose-related liver and kidney lesions in both lines. Selection lines did not differ significantly in the incidence of infarcts of hepatic lobules. However, at 30 and 40 mg/kg SPD doses, severity of this lesion was higher in affected S than in affected R mice. At the higher SPD doses, there also was a greater incidence of hepatic subacute cholangitis in S mice than in R mice. Foci of acute tubular necrosis were found in kidneys of mice receiving 20, 30, or 40 mg/kg SPD, with no protection against these lesions in the R line. Foci of tubular basophilia (indicative of tubular regeneration) were present in all line x dose subgroups, but incidence was not SPD dose-dependent in either line. In summary, divergent selection for weight gain response to ingestion of endophyte-infected fescue seed resulted in a favorable correlated response in survival following exposure to a chemically distinct toxin. It may be possible therefore, to select livestock populations for simultaneous resistance to a variety of toxins.