Abrupt burial imparts persistent changes to the bacterial diversity of turbidite-associated sediment profiles.

The emplacement of subaqueous gravity-driven sediment flows imposes a significant physical and geochemical impact on underlying sediment and microbial communities. Although previous studies have established lasting mineralogical and biological signatures of turbidite deposition, the response of bacteria and archaea within and beneath debris flows remains poorly constrained. Both bacterial cells associated with the underlying sediment and those attached to allochthonous material must respond to substantially altered environmental conditions and selective pressures. As a consequence, turbidites and underlying sediments provide an exceptional opportunity to examine (i) the microbial community response to rapid sedimentation and (ii) the preservation and identification of displaced micro-organisms. We collected Illumina MiSeq sequence libraries across turbidite boundaries at ~26 cm sediment depth in La Jolla Canyon off the coast of California, and at ~50 cm depth in meromictic Twin Lake, Hennepin County, MN. 16S rRNA gene signatures of relict and active bacterial populations exhibit persistent differences attributable to turbidite deposition. In particular, both the marine and lacustrine turbidite boundaries are sharply demarcated by the abundance and diversity of Chloroflexi, suggesting a characteristic sensitivity to sediment disturbance history or to differences in organic substrates across turbidite profiles. Variations in the abundance of putative dissimilatory sulfate-reducing Deltaproteobacteria across the buried La Jolla Canyon sediment-water interface reflect turbidite-induced changes to the geochemical environment. Species-level distinctions within the Deltaproteobacteria clearly conform to the sedimentological boundary, suggesting a continuing impact of genetic inheritance distinguishable from broader trends attributable to selective pressure. Abrupt, <1-cm scale changes in bacterial diversity across the Twin Lake turbidite contact are consistent with previous studies showing that relict DNA signatures attributable to sediment transport may be more easily preserved in low-energy, anoxic environments. This work raises the possibility that deep subsurface microbial communities may inherit variations in microbial diversity from sediment flow and deformation events.

Experimental precipitation of apatite pseudofossils resembling fossil embryos.

Certain phosphatic grains preserved in the rock record are interpreted as microfossils representing a diversity of microorganisms from bacteria to fossil embryos. In addition to bona fide primary biological features, phosphatic microfossils and fossil embryos commonly exhibit features that result from abiotic precipitation or diagenetic alteration. Distinguishing between abiotic and primary biological features can be difficult, and some features thought to represent biological tissue could instead be artifacts that are unrelated to the original morphology of a preserved organism. Here, we present experimentally generated, abiotically produced mineral precipitates that morphologically resemble biologically produced features, some of which may be observed in the rock record or noted in extant organisms, including embryos. These findings extend the diversity of biomorphic features known to result from abiotic precipitation.

Challenges and opportunities in evaluating a digital sexual health intervention in a clinic setting: Staff and patient views.

OBJECTIVES: The aim of the study was to gather the views of sexual health clinic staff and male clinic users regarding digital sexual health promotion and online trial procedures. METHODS: The Men's Safer Sex website was offered on tablet computers to men in the waiting rooms of three sexual health clinics, in a feasibility online randomised controlled trial (RCT). Interviews were conducted with 11 men who had participated in the trial and with nine clinic staff, to explore their views of the website and views of the online trial. Interviews were audio-recorded and transcribed, and we conducted a thematic analysis of interviews and of 281 free text comments from the online RCT outcome questionnaires. RESULTS: Clinic users and staff felt that digital interventions such as the Men's Safer Sex website are useful, especially if NHS endorsed. Pre-appointment waiting time presents a good opportunity for intervention but clinic users and staff felt that a website should supplement rather than replace face-to-face healthcare. The RCT procedures fitted well around clinical activities, but men did not self-direct to the tablet computers. Staff were more concerned about consent and confidentiality than clinic users, and staff and patients were frustrated by multiple technical problems. The trial outcome questionnaire was thought-provoking and could constitute an intervention in itself. Participants felt that clinics would need to promote a digital intervention and/or offer the site routinely to promote engagement. CONCLUSION: Digital interventions could usefully supplement in-person sexual health care, but there are important obstacles in terms of IT access in NHS settings, and in promoting engagement.

Increasing condom use in heterosexual men: development of a theory-based interactive digital intervention.

Increasing condom use to prevent sexually transmitted infections is a key public health goal. Interventions are more likely to be effective if they are theory- and evidence-based. The Behaviour Change Wheel (BCW) provides a framework for intervention development. To provide an example of how the BCW was used to develop an intervention to increase condom use in heterosexual men (the MenSS website), the steps of the BCW intervention development process were followed, incorporating evidence from the research literature and views of experts and the target population. Capability (e.g. knowledge) and motivation (e.g. beliefs about pleasure) were identified as important targets of the intervention. We devised ways to address each intervention target, including selecting interactive features and behaviour change techniques. The BCW provides a useful framework for integrating sources of evidence to inform intervention content and deciding which influences on behaviour to target.

Barite encrustation of benthic sulfur-oxidizing bacteria at a marine cold seep.

Crusts and chimneys composed of authigenic barite are found at methane seeps and hydrothermal vents that expel fluids rich in barium. Microbial processes have not previously been associated with barite precipitation in marine cold seep settings. Here, we report on the precipitation of barite on filaments of sulfide-oxidizing bacteria at a brine seep in the Gulf of Mexico. Barite-mineralized bacterial filaments in the interiors of authigenic barite crusts resemble filamentous sulfide-oxidizing bacteria of the genus Beggiatoa. Clone library and iTag amplicon sequencing of the 16S rRNA gene show that the barite crusts that host these filaments also preserve DNA of Candidatus Maribeggiatoa, as well as sulfate-reducing bacteria. Isotopic analyses show that the sulfur and oxygen isotope compositions of barite have lower δ(34)S and δ(18)O values than many other marine barite crusts, which is consistent with barite precipitation in an environment in which sulfide oxidation was occurring. Laboratory experiments employing isolates of sulfide-oxidizing bacteria from Gulf of Mexico seep sediments showed that under low sulfate conditions, such as those encountered in brine fluids, sulfate generated by sulfide-oxidizing bacteria fosters rapid barite precipitation localized on cell biomass, leading to the encrustation of bacteria in a manner reminiscent of our observations of barite-mineralized Beggiatoa in the Gulf of Mexico. The precipitation of barite directly on filaments of sulfide-oxidizing bacteria, and not on other benthic substrates, suggests that sulfide oxidation plays a role in barite formation at certain marine brine seeps where sulfide is oxidized to sulfate in contact with barium-rich fluids, either prior to, or during, the mixing of those fluids with sulfate-containing seawater in the vicinity of the sediment/water interface. As with many other geochemical interfaces that foster mineral precipitation, both biological and abiological processes likely contribute to the precipitation of barite at marine brine seeps such as the one studied here.

Horizontal gene transfer and the rock record: comparative genomics of phylogenetically distant bacteria that induce wrinkle structure formation in modern sediments.

Wrinkle structures are sedimentary features that are produced primarily through the trapping and binding of siliciclastic sediments by mat-forming micro-organisms. Wrinkle structures and related sedimentary structures in the rock record are commonly interpreted to represent the stabilizing influence of cyanobacteria on sediments because cyanobacteria are known to produce similar textures and structures in modern tidal flat settings. However, other extant bacteria such as filamentous representatives of the family Beggiatoaceae can also interact with sediments to produce sedimentary features that morphologically resemble many of those associated with cyanobacteria-dominated mats. While Beggiatoa spp. and cyanobacteria are metabolically and phylogenetically distant, genomic analyses show that the two groups share hundreds of homologous genes, likely as the result of horizontal gene transfer. The comparative genomics results described here suggest that some horizontally transferred genes may code for phenotypic traits such as filament formation, chemotaxis, and the production of extracellular polymeric substances that potentially underlie the similar biostabilizing influences of these organisms on sediments. We suggest that the ecological utility of certain basic life modes such as the construction of mats and biofilms, coupled with the lateral mobility of genes in the microbial world, introduces an element of uncertainty into the inference of specific phylogenetic origins from gross morphological features preserved in the ancient rock record.

Filamentous sulfur bacteria preserved in modern and ancient phosphatic sediments: implications for the role of oxygen and bacteria in phosphogenesis.

Marine phosphate-rich sedimentary deposits (phosphorites) are important geological reservoirs for the biologically essential nutrient phosphorous. Phosphorites first appear in abundance approximately 600 million years ago, but their proliferation at that time is poorly understood. Recent marine phosphorites spatially correlate with the habitats of vacuolated sulfide-oxidizing bacteria that store polyphosphates under oxic conditions to be utilized under sulfidic conditions. Hydrolysis of the stored polyphosphate results in the rapid precipitation of the phosphate-rich mineral apatite-providing a mechanism to explain the association between modern phosphorites and these bacteria. Whether sulfur bacteria were important to the formation of ancient phosphorites has been unresolved. Here, we present the remains of modern sulfide-oxidizing bacteria that are partially encrusted in apatite, providing evidence that bacterially mediated phosphogenesis can rapidly permineralize sulfide-oxidizing bacteria and perhaps other types of organic remains. We also describe filamentous microfossils that resemble modern sulfide-oxidizing bacteria from two major phosphogenic episodes in the geologic record. These microfossils contain sulfur-rich inclusions that may represent relict sulfur globules, a diagnostic feature of modern sulfide-oxidizing bacteria. These findings suggest that sulfur bacteria, which are known to mediate the precipitation of apatite in modern sediments, were also present in certain phosphogenic settings for at least the last 600 million years. If polyphosphate-utilizing sulfide-oxidizing bacteria also played a role in the formation of ancient phosphorites, their requirements for oxygen, or oxygen-requiring metabolites such as nitrate, might explain the temporal correlation between the first appearance of globally distributed marine phosphorites and increasing oxygenation of Neoproterozoic oceans.

Computer-based interventions for sexual health promotion: systematic review and meta-analyses.

This systematic review was conducted to determine the effects of self-help interactive computer-based interventions (ICBIs) for sexual health promotion. We searched 40 databases for randomized controlled trials (RCTs) of computer-based interventions, defining 'interactive' as programmes that require contributions from users to produce personally relevant material. We conducted searches and analysed data using Cochrane Collaboration methods. Results of RCTs were pooled using a random-effects model with standardized mean differences for continuous outcomes and odds ratios (ORs) for binary outcomes, with heterogeneity assessed using the I(2) statistic. We identified 15 RCTs of ICBIs (3917 participants). Comparing ICBIs to minimal interventions, there were significant effects on sexual health knowledge (standardized mean difference [SMD] 0.72, 95% confidence interval [CI] 0.27-1.18); safer sex self-efficacy (SMD 0.17, 95% CI 0.05-0.29); safer-sex intentions (SMD 0.16, 95% CI 0.02-0.30); and sexual behaviour (OR 1.75, 95% CI 1.18-2.59). ICBIs had a greater impact on sexual health knowledge than face-to-face interventions did (SMD 0.36, 95% CI 0.13-0.58). ICBIs are effective tools for learning about sexual health, and show promising effects on self-efficacy, intention and sexual behaviour. More data are needed to analyse biological outcomes and cost-effectiveness.

Experimental taphonomy of giant sulphur bacteria: implications for the interpretation of the embryo-like Ediacaran Doushantuo fossils.

The Ediacaran Doushantuo biota has yielded fossils interpreted as eukaryotic organisms, either animal embryos or eukaryotes basal or distantly related to Metazoa. However, the fossils have been interpreted alternatively as giant sulphur bacteria similar to the extant Thiomargarita. To test this hypothesis, living and decayed Thiomargarita were compared with Doushantuo fossils and experimental taphonomic pathways were compared with modern embryos. In the fossils, as in eukaryotic cells, subcellular structures are distributed throughout cell volume; in Thiomargarita, a central vacuole encompasses approximately 98 per cent cell volume. Key features of the fossils, including putative lipid vesicles and nuclei, complex envelope ornament, and ornate outer vesicles are incompatible with living and decay morphologies observed in Thiomargarita. Microbial taphonomy of Thiomargarita also differed from that of embryos. Embryo tissues can be consumed and replaced by bacteria, forming a replica composed of a three-dimensional biofilm, a stable fabric for potential fossilization. Vacuolated Thiomargarita cells collapse easily and do not provide an internal substrate for bacteria. The findings do not support the hypothesis that giant sulphur bacteria are an appropriate interpretative model for the embryo-like Doushantuo fossils. However, sulphur bacteria may have mediated fossil mineralization and may provide a potential bacterial analogue for other macroscopic Precambrian remains.

Sexually transmitted infections in women who have sex with women.

OBJECTIVES: To describe the prevalence of sexually transmitted infection (STIs) in a sample of women who have sex with women (WSW) and to identify risk factors for the acquisition of STI. METHOD: Cross sectional survey. Questionnaire for demographic, sexual history, and sexual practice data linked with the results of genitourinary examination. 708 new patients attending two sexual health clinics for lesbians and bisexual women in London were surveyed. RESULTS: A majority of WSW reported sexual histories with men (82%). Bacterial vaginosis and candida species were commonly diagnosed (31.4% and 18.4% respectively). Genital warts, genital herpes, and trichomoniasis were infrequently diagnosed (1.6%, 1.1%, and 1.3% respectively). Chlamydia, pelvic inflammatory disease, and gonorrhoea infections were rare (0.6%, 0.3%, and 0.3% respectively) and diagnosed only in women who had histories of sex with men. CONCLUSIONS: Although we have demonstrated a low prevalence of STI, WSW may have sexual histories with men as well as women or histories of injecting drug use, and are therefore vulnerable to sexually transmitted or blood borne infections. Diagnosis of trichomoniasis, genital herpes, and genital warts in three women who had no history of sex with men implies that sexual transmission between women is possible.

Sexual behaviour of lesbians and bisexual women.

OBJECTIVES: To provide data about the sexual histories of a large sample of lesbians and bisexual women, to inform those who provide health care or carry out research with women who may be sexually active with other women. DESIGN: Cross sectional survey. SETTING/SUBJECTS: 803 lesbians and bisexual women attending, as new patients, lesbian sexual health clinics, and 415 lesbians and bisexual women from a community sample. MAIN OUTCOME MEASURES: Self reported sexual history and sexual practice with both male and female partners. RESULTS: 98% of the whole sample gave a history of sexual activity with women, 83% within the past year, with a median of one female partner in that year. 85% of the sample reported sexual activity with men; for most (70%) this was 4 or more years ago. First sexual experience tended to be with a man (median 18 years old), with first sexual experience with a woman a few years later (median 21 years). Oral sex, vaginal penetration with fingers, and mutual masturbation were the most commonly reported sexual practices between women. Vaginal penetration with penis or fingers and mutual masturbation were the most commonly reported sexual activities with men. CONCLUSIONS: These data from the largest UK survey of sexual behaviour between women to date demonstrate that lesbians and bisexual women may have varied sexual histories with both male and female partners. A non-judgmental manner and careful sexual history taking without making assumptions should help clinicians to avoid misunderstandings, and to offer appropriate sexual health advice to lesbians and bisexual women.

Podotrochlear bursa endoscopy in the horse: a cadaver study.

OBJECTIVES: To evaluate podotrochlear bursa (navicular bursa) endoscopy as a diagnostic technique in horses and to correlate observations to radiographic and pathologic findings. STUDY DESIGN: Descriptive study. SAMPLE POPULATION: Seventeen equine cadaver forelimbs. METHODS: Five standard radiographic views of the navicular region and a bursographic study with lateromedial and caudal tangential radiographic views were taken of each forelimb. Radiographic scoring of the navicular bone (0, excellent; 1, good; 2, fair; 3, poor) was performed using a previously reported technique. Endoscopic examination was performed using a 30 degrees wide-angle forward oblique-viewing, 4-mm outside diameter (OD), arthroscope. Four examiners using recorded videotapes made independent evaluations of bursal endoscopy. The specimens were then dissected and examined to verify radiographic and endoscopic findings. RESULTS: The distribution of radiographic scores (RS) were 0 (5 limbs), 1 (7), 2 (2), and 3 (3). Abnormal endoscopic findings (fibrillation of the deep digital flexor tendon, a defect in the navicular bone fibrocartilage, and synovial hyperplasia) were identified in 3 limbs (2 with an RS of 1, and 1 with an RS of 3). The endoscopic observations made in the two RS 1 bursae were not confirmed on gross examination, whereas they were in the RS 3 specimen, which also had the only abnormal bursogram. Evaluation of the bursa on the side ipsilateral to the arthroscope portal was difficult. Complications of the technique included inadvertent penetration of the distal interphalangeal joint and the digital sheath, and superficial scoring of the navicular bone fibrocartilage. CONCLUSIONS: Podotrochlear bursa endoscopy is feasible and may be a useful technique in identifying early abnormalities associated with podotrochleosis. CLINICAL RELEVANCE: In horses with podotrochleosis, endoscopic examination of the podotrochlear bursa may improve identification of pathologic changes within the bursa.

Comparison of 2 techniques for regional antibiotic delivery to the equine forelimb: intraosseous perfusion vs. intravenous perfusion.

The purpose of this study was to compare the synovial fluid concentrations and pharmacokinetics of amikacin in the equine limb distal to the carpus following intraosseous and intravenous regional perfusion. The front limbs of 6 horses were randomly assigned to either intraosseous or intravenous perfusion. A tourniquet was placed distal to each carpus and the limb perfused with 500 mg of amikacin. Systemic blood samples and synovial fluid samples were collected over 70 min from the distal interphalangeal (DIP) joint, metacarpophalangeal joint, and digital flexor sheath. The tourniquet was removed following the 30 min sample collection. The mean peak amikacin concentration for the DIP joint was significantly higher with intravenous perfusion. There were no significant differences in time to peak concentration or elimination half-life between methods at each synovial structure. Each technique produced mean peak concentrations ranging from 5 to 50 times that of recommended peak serum concentrations for therapeutic efficacy.

Outcome of limb amputations in wapiti: 13 cases (1995-2001).

The object of this investigation was to determine the outcome of limb amputation in wapiti. Medical records of 13 wapiti that underwent limb amputation were reviewed to determine age, weight, sex, injury preceding amputation, limb amputated, amputation location, length of hospital stay, complications, and outcome. Ages ranged from 3 months to 8 years and weights from 70 kg to 280 kg. All animals were female. Eleven animals sustained catastrophic long bone fractures prior to amputation. Five animals had front limb amputations and 8 had hind limb amputations. Of these animals, 1 with a front limb amputaiton and 5 with hind limb amputations survived. Postsurgical inability to stand is associated with hospitalization of > 1 day. Of the 13 wapiti reviewed, 5 with hind limb amputations have produced and reared offspring. Hind limb amputation can be considered a viable alternative to euthanasia when catastrophic orthopedic injuries occur in female wapiti.

An evaluation of chemical arthrodesis of the proximal interphalangeal joint in the horse by using monoiodoacetate.

The use of monoiodoacetate (MIA) for arthrodesis of the proximal interphalangeal joint (PIJ) and the effect of exercise on the degree of fusion were investigated. Eight horses received 3 injections (Weeks 0, 3, 6) of MIA (2 mL; 60 mg/mL) into the right or left front PIJ. Peri-operatively, the horses received phenylbutazone, butorphanol, and abaxial sesamoidean nerve blocks to relieve pain. During the study, the horses were monitored for general health, lameness, and swelling around the injection area. Radiographs were taken biweekly to evaluate bony fusion. Horses were randomly divided into non-exercised and exercised groups. Exercise consisted of 20 minutes of trotting on a treadmill (4 m/s), 3 days per week for 13 weeks. The horses were euthanized at 24 weeks. Slab sections of the PIJ were evaluated grossly and radiographically for bony fusion. Histologic examinations were performed to evaluate articular cartilage. Three horses were excluded from the study after developing soft tissue necrosis around the injection site, septic arthritis, and necrotic tendinitis. The remaining horses remained healthy, developed a grade 1 to 4 lameness with minimal to severe swelling in the PIJ region. All 5 horses showed radiographic evidence of bony fusion, however, no fusion was present when injected joints were examined on postmortem examination. Histologic examination revealed thinning of the cartilage, diffuse necrosis of chondrocytes, with the calcified zone intact. Subjectively, exercise did not influence the degree of cartilage destruction. Based on this study, chemical arthrodesis cannot be advocated in clinical cases because of the high complication rate and lack of bony fusion.

Lesbians and cervical screening.

Confusion exists in clinical practice about whether lesbians should be offered routine cervical smears. We found cervical smear abnormalities in a sample of 624 lesbians, including those who had never been sexually active with men. These findings suggest that lesbians should be routinely offered cervical cytology as part of the national screening programme. Evidence of human papilloma virus (HPV) infection in the 'exclusively lesbian' group indicates that sexual transmission of HPV may occur between women. The belief by some lesbians that they have less need for cervical smears, coupled with poor uptake of cervical screening by a significant proportion, demonstrates a need for education of lesbians and health service providers.

Age-related changes to the molecular and cellular components of equine flexor tendons.

Specific tendons show a high incidence of partial central core rupture which is preceded by degeneration. In the performance horse, the superficial digital flexor tendon (SDFT) is most often affected. We have described previously the molecular changes that are associated with degeneration in the central core region of the equine SDFT. The pathophysiological mechanism leading to change in synthetic activity of central zone cells in degenerated tendons is not known. In this study, we test the hypothesis that ageing results in matrix composition changes within the central zone of the SDFT. Extracellular matrix composition and cellularity were analysed in equine SDFTs collected from Thoroughbred horses and compared with a flexor tendon which rarely shows degenerative change and subsequent injury (deep digital flexor tendon, DDFT). Data were examined for age-related changes to central and peripheral zone tissue of the SDFT and DDFT. Ageing in both tendons (SDFT and DDFT) resulted in a significant increase in collagen-linked fluorescence and a decrease in cellularity in the DDFT but not the SDFT. The central zone tissue from the SDFT had a significantly higher proportion of type III collagen than the peripheral zone of the tendon. The highest level of type III collagen was found in the central zone tissue of the SDFT from the older group of horses and this may represent the early stages of a degenerative change. Collagen content did not differ between the 2 flexor tendons; however, there were differences in collagen type and organisation. The SDFT had a higher type III collagen content, higher levels of the mature trifunctional collagen crosslink hydroxylysylpyridinoline, lower total chondroitin sulphate equivalent glycosaminoglycan content, smaller diameter collagen fibrils and a higher cellularity than the DDFT. In conclusion, differences in macromolecular composition exist between the flexor tendons and ageing contributes to a tendon specific change in composition.

Effect of feed rate and drill speed on temperatures in equine cortical bone.

OBJECTIVE: To examine the amount of heat generated in equine cortical bone by a 6.2-mm drill, using low- and high-speed and controlled feed rate drilling. SAMPLE POPULATION: 10 metacarpal bones harvested from five 2-year-old draft-type horses. PROCEDURE: Drilling on metacarpal bones was done using a machine shop mill with which the feed rate and drill speed could be precisely controlled. Bones were drilled, using 6 combinations of feed rate (1, 2, and 3 mm advance/s) and drill speed (317 and 1,242 revolutions/min [rpm], with maximal temperatures recorded by thermocouples placed 1, 1.5, and 2 mm from the drill. Maximal temperatures were evaluated for the effect of feed rate, drill speed, cortical thickness, and distance from the drill, using linear regression analysis. RESULTS: Increasing feed rate from 1 to 2 and from 2 to 3 mm/s significantly decreased mean maximal temperature. Increasing drill speed from 317 to 1242 rpm significantly increased mean maximal temperature. Increasing cortical thickness significantly increased mean maximal temperature, and increasing the distance from the drill hole significantly decreased mean maximal temperatures. CONCLUSIONS: On the basis of our results, we recommend using low drill speeds while applying sufficient axial force to advance the drill as rapidly as possible through the bone. CLINICAL RELEVANCE: Results of using this in vitro model suggest that temperatures at the drill-bone interface may be sufficiently high to result in significant thermal necrosis when drilling equine cortical bone.

Management of limb fractures in wapiti (Cervus elaphus): 22 cases (1993-1997).

OBJECTIVE: To determine treatment and outcome of a series of wapiti (elk) with fractures of the limbs. DESIGN: Retrospective study. ANIMALS: 22 wapiti. PROCEDURE: Medical records were reviewed to determine affected limb and bone, fracture configuration, method of treatment, outcome, and complications. RESULTS: 2 animals had fractures of the humerus; 8 had fractures of the radius, ulna, or both; 5 had fractures of the third metacarpal bone; 3 had fractures of the tibia; 2 had fractures of the femur; and 2 had fractures of the tarsal bones. Most fractures (n = 11) were closed, displaced, nonarticular fractures; 6 fractures were open. Four animals died or were euthanatized prior to fracture treatment, 2 were not treated because fractures had already healed, and 14 underwent fracture repair. In the remaining 2 animals, the affected limb was amputated. Five animals developed nonfatal complications (wound dehiscence, osteomyelitis [2 animals], delayed union, and malunion) and 2 developed fatal complications (gastrocnemius rupture and femoral fracture during recovery). Overall, 16 animals were discharged from the hospital, and all were doing well at follow-up, 2 months to 4 years after discharge. CLINICAL IMPLICATIONS: In wapiti, limb fractures can be successfully treated by means of internal or external fixation. The high rate of fracture healing, even among wapiti with open fractures, should encourage veterinarians to repair limb fractures in wapiti.

Effect of ischemia and reperfusion on neutrophil accumulation in equine microvascular tissue flaps.

OBJECTIVE: To investigate neutrophil accumulation after ischemia and reperfusion (IR) in microvascular tissue flaps in horses. STUDY DESIGN: Randomized controlled experiment. SAMPLE POPULATION: A total of 8 horses between 1 and 10 years of age, 4 of each sex. METHODS: Control and experimental myocutaneous island flaps based on the superficial branch of the deep circumflex iliac vessels were dissected on each horse. Atraumatic vascular clamps were applied to the pedicle of the experimental flap for 90 minutes and then removed to allow reperfusion. Based on the assumption that rapid infiltration of neutrophils into affected tissues is a hallmark of IR injury, radiolabeled autogenous leukocytes were used to indirectly quantify neutrophil accumulation in flap tissues. Labeled leukocytes were administered through a jugular catheter 30 minutes before flap reperfusion. Biopsies were collected from each flap over a 6 hour postischemia time period; in group 1 (n = 4) from 0 to 6 hours postischemia, and in group 2 (n = 4) from 24 to 30 hours postischemia. Biopsies were examined scintigraphically and histologically for evidence of neutrophil infiltration. RESULTS: All control flaps survived and 6 of 8 experimental flaps survived. There was no significant evidence of acute neutrophil infiltration into flap tissues after reperfusion in either group. CONCLUSIONS: The results of this study suggest that equine myocutaneous flap tissues can survive a 90-minute ischemic period and reperfusion. No significant evidence of the occurrence of IR injury in flap tissues was found. CLINICAL RELEVANCE: The reasons for the previously reported failures of equine free tissue transfer remain uncertain, but they do not appear to be caused by neutrophil mediated injury associated with ischemia and reperfusion.