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.

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.

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.

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.

Osteochondritis dessicans and subchondral cystic lesions in draft horses: a retrospective study.

The clinical features, radiographic findings, treatment, and outcome in 51 draft horses with osteochondritis dessicans (OCD) or subchondral cystic lesions (SC) are reported. Clydesdale and Percheron were the most commonly affected breeds, and affected animals represented only 5% of the hospital population of draft horses. Horses were most frequently affected in the tibiotarsal joints and 73% (24 of 33 cases) of the horses with tibiotarsal effusion were affected bilaterally. Osteochondritis dessicans of the distal intermediate ridge was the most common lesion found in the tibiotarsal joint. The stifle was also frequently affected; 87% (13 of 15 cases) of horses with femoropatellar OCD only were lame, and lesions were most commonly located on the lateral trochlear ridge. Sixteen cases were managed conservatively, 30 received surgery, and 5 were euthanized. Lameness, effusion, or both clinical signs resolved in more than 50% of surgically treated cases, but clinical signs improved in 30% of conservatively-managed cases.

Comparison of herniorrhaphy versus clamping of umbilical hernias in horses: a retrospective study of 93 cases (1982-1994).

Many uncomplicated umbilical hernias have been managed successfully in foals by the application of a hernia clamp. Isolated reports of complications following clamp application have led some authors to suggest that it is an unsuitable method of treatment. Little information has been published comparing the complication rates associated with the use of hernia clamps and herniorrhaphy in the treatment of umbilical hernias. The purpose of this retrospective study was to report the characteristics of clinical cases of umbilical hernia and to compare the complication rates following these 2 treatment approaches. Information was collected from records or from owners to identify the occurrence of complications and owner satisfaction following treatment. Of 93 cases, 10 complicated and 18 uncomplicated hernias were treated by herniorrhaphy, 40 uncomplicated hernias were treated by clamping, 1 originally uncomplicated hernia was treated by both techniques, and 24 cases were untreated. Nineteen percent of uncomplicated hernias treated by herniorrhaphy, and 19% of those clamped developed minor complications. This study demonstrates that although minor complications may be associated with either technique, they generally do not result in significant morbidity.

An examination of the occurrence of surgical wound infection following equine orthopaedic surgery (1981-1990).

Post operative surgical wound infection rates were determined 452 cases of equine orthopaedic surgery performed at the Western College of Veterinary Medicine, Saskatoon, Saskatchewan, between January 1, 1981 and December 31, 1990. Only surgical procedures classified as clean or clean-contaminated by the National Research Council were included in this study. The overall post operative infection rate was 10.0% (45 of 452). Clean surgeries (n = 433) had an 8.1% infection rate while clean-contaminated surgeries (n = 19) had a 52.6% infection rate. Information collected from the medical records was used in univariate and multivariate logistic regression models to evaluate significant determinates of post operative infection. Significant determinates of post operative infection were: surgical classification, orthopaedic involvement, duration of surgery, administration of preoperative antibiotics and gender. Clean-contaminated surgeries had an increased risk of infection compared to clean surgeries (odds ratio (OR) = 24.3), procedures involving long bones had an increased risk of infection compared to procedures involving articular surfaces (OR = 5.1), surgeries lasting 90 minutes or longer had an increased risk of infection compared to those less than 90 minutes (OR = 3.6), administration of preoperative antibiotics was associated with an increased risk of infection (OR = 4.6) and female patients were 2.6 times more likely to develop post operative infection than male patients.

Mechanical properties of suture materials in vitro and after in vivo implantation in horses.

Tensile testing of reproducible loops of size 5 braided polyester, size 2 polyglycolic acid, size 2 monofilament nylon, and size 2 polydioxanone sutures was performed in vitro and after subcutaneous implantation in horses for 7, 14, and 28 days. Maximum breaking strength, energy absorption, and percentage elongation to breakage point were measured. Size 5 braided polyester had the highest maximum breaking strength and energy absorption over 28 days. Polydioxanone had better mechanical performance over 28 days than did polyglycolic acid. On day 28, none of these parameters was measurable in polyglycolic acid. Monofilament nylon had the lowest breaking strength of the three materials tested on day 28.

Proximal interphalangeal arthrodesis in the horse. A retrospective study and a modified screw technique.

Arthrodesis of the proximal interphalangeal joint was used to treat lameness resulting from osteoarthrosis and for closed subluxation in 35 horses. Six horses had bilateral arthrodeses. Several conventional internal fixation techniques and a three converging screw method were used. Criteria for success included the horse performing its previous or intended athletic activity and the owner being satisfied with the outcome. Using these criteria, a successful outcome was obtained in 65% of the 26 animals in which adequate follow-up was available. A successful outcome was observed in four of six horses with bilateral arthrodeses. The internal fixation technique used did not influence the success rate, and the duration of postoperative casting was similar in successful and unsuccessful cases. The success rate of proximal interphalangeal arthrodeses was 46% in the fore limbs and 83% in the hind limbs. Complications included infection, cast ulcers, bone or implant failure, implant loosening, and laminitis.

Balloon-tipped catheter arterial occlusion for prevention of hemorrhage caused by guttural pouch mycosis: 13 cases (1982-1985).

Epistaxis, caused by guttural pouch mycosis, was treated by balloon-tipped catheter and ligature occlusion of the involved arteries in 13 horses. In 7 horses, more than one artery was catheterized. Serious postoperative hemorrhage was prevented in all horses. Long-term endoscopic follow-up examination was possible in 8 horses, and all had complete regression of the fungal lesion as early as 5 weeks after surgery. Six of the 8 horses did not receive medical treatment. Problems related to the use of the balloon-tipped catheter technique were rare. There were incisional infections in 3 horses, catheter breakage during removal occurred twice, and in one horse, a catheter was inappropriately placed.

Bilateral carpus valgus with cranial bowing of the distal radius in a foal.

Bilateral carpus valgus with concomitant outward rotation and cranial bowing of the distal radii was diagnosed in a crossbred foal. The foal was not lame on admission and showed no radiographic evidence of carpal bone abnormalities. Surgery was limited to the most severely affected leg, and consisted of a combination of growth promotion (periosteal transection and stripping) and temporary physeal retardation (transphyseal bridging) procedures. Correction of the valgus deformity was nearly complete in the operated limb and substantial improvement was observed in the cranial bowing and outward rotation in both limbs, five months postoperatively.

Bovine arthritides. Classification, diagnosis, prognosis, and treatment.

Bovine arthritides are an important aspect of food animal practice, and a good understanding of these conditions allows the practitioner to develop effective treatment regimens. This article discusses the complexities of joint diseases and the problems associated with their diagnoses and treatments.

Herniation of small intestine through the right lateral ligament of the bladder in a bull.

A three year old Charolais bull was examined because of anorexia and depression of five days duration and progressive abdominal distention. Intestinal obstruction was diagnosed. A right flank celiotomy allowed diagnosis and correction of a herniated jejunoileal loop through the right lateral ligament of the bladder. An annular constriction located in mid-ileum was by-passed by ileocecal side-to-side anastomosis. The bull's appetite and fecal production returned to normal within 72 hours of surgery. Ten months following discharge the bull was reported to be well.