Rat eustachian tube synthesizes disaturated phosphatidylcholine.

Otitis media results when the eustachian tube fails to adequately ventilate the middle ear. A surface tension-lowering substance may be required for normal tube opening, especially in young children with poorly developed naso-pharyngeal musculature. We report here that rat eustachian tube epithelium synthesizes disaturated phosphatidylcholine, which is recognized as the surface tension-lowering substance of pulmonary surfactant.

Efficient incorporation of large (>2 kb) heterologies into heteroduplex DNA: Pms1/Msh2-dependent and -independent large loop mismatch repair in Saccharomyces cerevisiae.

DNA double-strand break (DSB) repair in yeast is effected primarily by gene conversion. Conversion can conceivably result from gap repair or from mismatch repair of heteroduplex DNA (hDNA) in recombination intermediates. Mismatch repair is normally very efficient, but unrepaired mismatches segregate in the next cell division, producing sectored colonies. Conversion of small heterologies (single-base differences or insertions <15 bp) in meiosis and mitosis involves mismatch repair of hDNA. The repair of larger loop mismatches in plasmid substrates or arising by replication slippage is inefficient and/or independent of Pms1p/Msh2p-dependent mismatch repair. However, large insertions convert readily (without sectoring) during meiotic recombination, raising the question of whether large insertions convert by repair of large loop mismatches or by gap repair. We show that insertions of 2.2 and 2.6 kbp convert efficiently during DSB-induced mitotic recombination, primarily by Msh2p- and Pms1p-dependent repair of large loop mismatches. These results support models in which Rad51p readily incorporates large heterologies into hDNA. We also show that large heterologies convert more frequently than small heterologies located the same distance from an initiating DSB and propose that this reflects Msh2-independent large loop-specific mismatch repair biased toward loop loss.

Multiple heterologies increase mitotic double-strand break-induced allelic gene conversion tract lengths in yeast.

Spontaneous and double-strand break (DSB)-induced allelic recombination in yeast was investigated in crosses between ura3 heteroalleles inactivated by an HO site and a +1 frameshift mutation, with flanking markers defining a 3.4-kbp interval. In some crosses, nine additional phenotypically silent RFLP mutations were present at approximately 100-bp intervals. Increasing heterology from 0.2 to 1% in this interval reduced spontaneous, but not DSB-induced, recombination. For DSB-induced events, 75% were continuous tract gene conversions without a crossover in this interval; discontinuous tracts and conversions associated with a crossover each comprised approximately 7% of events, and 10% also converted markers in unbroken alleles. Loss of heterozygosity was seen for all markers centromere distal to the HO site in 50% of products; such loss could reflect gene conversion, break-induced replication, chromosome loss, or G2 crossovers. Using telomere-marked strains we determined that nearly all allelic DSB repair occurs by gene conversion. We further show that most allelic conversion results from mismatch repair of heteroduplex DNA. Interestingly, markers shared between the sparsely and densely marked interval converted at higher rates in the densely marked interval. Thus, the extra markers increased gene conversion tract lengths, which may reflect mismatch repair-induced recombination, or a shift from restoration- to conversion-type repair.

Success and failure rates of cylinder implants in type IV bone.

It is well documented that implant success rates are much lower in Type IV bone than in Types I, II, and III. However, all of these studies have reported on the use of screw type implants. The present study demonstrates the efficacy of cylinder implant use in Type IV bone. A total of 513 cylinders were placed in Type IV bone and were followed for 0 to 60+ months in function. The absolute success rate was 95.7%. Of the 22 fixture failures encountered, 8 were discovered at the time of second stage surgery, 3 during the first year following uncovering, and 11 occurred after 24 to 36 months in function. A possible rationale for the higher success rate of cylinders as compared to that reported for screw type implants in Type IV bone is presented. Further well-controlled studies directly comparing various implant designs in a range of bony sites are needed to better understand and to fully document the differences suggested by the present study.

Eight-year clinical retrospective study of titanium plasma-sprayed and hydroxyapatite-coated cylinder implants.

A total of 1,202 press-fit cylinder implants were placed in 479 patients from March 1986 to March 1994. The patients' ages ranged from 14 to 88 years. The implants included 889 titanium plasma-sprayed implants and 313 hydroxyapatite-coated implants. There were no statistically significant differences in the distribution of hydroxyapatite-coated and titanium plasma-sprayed implants based on implant location, type of restoration, age, and sex. Although differences in long-term success rates based on simple percentages were also not statistically significant, cumulative survival rates based on life table analysis up to 96 months were 92.7% for titanium plasma-sprayed systems and 77.8% for hydroxyapatite-coated systems. Graphical interpretations of these data revealed interesting contrasts, including the timing and results of implant failure, which are discussed in detail.

Tissue preservation and maintenance of optimum esthetics: a clinical report.

Today, most tooth replacement in the esthetic zone is done using implants placed in a delayed surgical protocol. Unfortunately, this delay can result in loss of both hard and soft tissue during the healing period, necessitating guided tissue regeneration techniques at the time of implant placement. Recent developments with tapered implants have facilitated predictable immediate implant placement, preserving the osseous structure surrounding the socket. Further developments with custom healing abutments can preserve the crestal soft tissues, including the papillae. This article reviews techniques that provide for the preservation of both bone and soft tissue while enhancing the esthetic results around implants.

Six-year clinical and histologic study of sinus-lift grafts.

This study retrospectively evaluated the results of 36 sinus-lift graft augmentations performed to place 66 implant cylinders in the posterior maxilla where vertical bone height was less than ideal. Grafts were accomplished with porous hydroxyapatite (HA) alone, porous HA mixed with autogenous bone removed from the iliac crest, and HA combined with autogenous bone removed from within the mouth. Nineteen core biopsy specimens were taken from different grafts at time intervals ranging from 4 to 36 months from the time of grafting. These cores were evaluated using histomorphometric analysis to yield data comparing volume fractions of bone formation, allowing comparison of different graft materials and healing times. Grafts using porous HA alone on mean produced 16.38% bone by volume after 6 months. After the same healing time, grafts using HA and hip bone on mean produced 19.30% bone by volume compared with an 11.30% bone volume when using HA and bone harvested intraorally. Evaluation of cores taken at 19 and 36 months revealed greater volumes of bone formation. Recommendations based on clinical and histologic results are discussed in detail.

The use of IMZ osseointegrated implants in partially and completely edentulous patients: success and failure rates of 2,023 implant cylinders up to 60+ months in function.

A total of 974 patients were treated with 2,023 IMZ implants. A variety of prosthodontic designs were utilized. These included replacement of single teeth, use as pier abutments, and for totally implant-supported prostheses. The implants were followed in function for 6 to 60+ months. Absolute success rates were 96.4% and 98.4% in the maxilla and mandible, respectively. Cumulative success rates at the end of the study were 92.9% and 95.8% in the maxilla and mandible, respectively. The use of an intramobile element is also discussed.

Pheochromocytoma in 50 dogs.

Fifty dogs with pheochromocytoma were identified in a retrospective study of a 9-year period. For 24 of 50 dogs (48%), the tumor was an incidental finding during necropsy or surgery. Presenting signs were referrable to the nervous system in 7 of the 26 symptomatic dogs (27%); were referrable to the cardiopulmonary system in 7 of 26 dogs (27%); or were nonspecific, reflecting general systemic disease, in 17 of 26 dogs (65%). Abnormal clinical findings were highly varied but were also generally referrable to the cardiopulmonary and nervous systems. Six of 7 dogs (86%) evaluated were hypertensive (systolic range, 164 to 325 mm Hg; diastolic range, 110 to 198 mm Hg). Serum biochemical findings were nonspecific, although 11 of 39 dogs (28%) were hypercholesterolemic. Abdominal fluid samples were analyzed in 6 dogs; 3 were nondiagnostic, and 3 were interpreted as lymphosarcoma. The imaging studies that were of most value included abdominal radiographs (mass identified in 9 of 16 dogs [56%]), caudal vena caval angiography (tumor thrombus correctly diagnosed in 4 of 7 dogs [57%]), and abdominal ultrasonography (mass seen in 5 of 6 dogs [83%] and tumor thrombus seen in 3 of 5 dogs [60%]). Local tumor invasion was present in 26 of 50 dogs (52%), regional lymph node metastases in 6 of 50 dogs (12%), and distant metastases in 12 of 50 dogs (24%). Cause of death was tumor-related in 19 of 50 dogs (38%) and non-tumor related in 28 of 50 dogs (54%).

Bone marrow cytological findings in 4 dogs and a cat with hemophagocytic syndrome.

Hemophagocytic syndrome or hemophagic histiocytosis was diagnosed in 4 dogs and 1 cat by evaluation of bone marrow aspirate smears. One of the dogs had a suspected infection with canine parvovirus and a confirmed infection with Salmonella spp, 2 dogs had presumptive diagnoses of myeloproliferative and lymphoproliferative disease, respectively, and 1 dog died without a diagnosis. The cat had hepatic lipidosis and lesions compatible with feline calicivirus infection. All animals had cytopenias involving 2 or more cell lines, and fragmented erythrocytes in the blood, along with mild to moderate increases in the number of macrophages in the bone marrow. Numerous marrow macrophages contained phagocytized hematopoietic cells. Other cytological features of the bone marrow were variable in each patient, but the degree of response in the blood was inadequate, even in those with bone marrow hyperplasia. The phagocytosis of hematopoietic elements did not appear to be caused by a primary immune disorder, but rather by the inappropriate activation of normal macrophages secondary to infectious, neoplastic, or metabolic diseases. These findings suggest that hemophagocytic syndrome may be an important factor in the development of cytopenias; the data also support the cytological evaluation of bone marrow aspirates as an aid in the diagnosis of hemophagocytic syndrome.

Exacerbation of hyperlactatemia by infusion of lactated Ringer's solution in dogs with lymphoma.

Blood lactate concentrations and acid-base status of six dogs with lymphoma were compared statistically with those from six healthy control dogs before, during, and after a 6-hour infusion of lactated Ringer's solution (LRS). Blood lactate concentrations in dogs with lymphoma were significantly (P less than 0.05) higher immediately before, and at the 1-, 2-, 4-, and 6-hour time periods after infusion when compared with controls. Blood lactate concentrations increased significantly (P = 0.016) after the first hour of infusion in dogs with lymphoma but did not increase in the control dogs. The increase in blood lactate concentrations over baseline values after 1 hour of LRS infusion was significantly (P = 0.008) greater in dogs with lymphoma when compared with controls. Blood lactate concentrations returned to baseline levels after 2 hours of infusion in dogs with lymphoma, suggesting that dogs with lymphoma have a transient inability to handle increased lactate loads when compared with controls. However, the potential to augment lactate use, clearance, or both is present and does occur over time. Blood gas values were not significantly altered within the lymphoma or control dog groups after 6 hours of LRS infusion. Blood bicarbonate concentrations in dogs with lymphoma were significantly decreased before and after LRS infusion when compared with controls.

A syndrome resembling lymphomatoid granulomatosis in the dog.

Lymphomatoid granulomatosis (LYG) was diagnosed in seven dogs. Most of the affected dogs were young to middle-aged, and there was no breed or sex predilection. Basophilia was detected in six of the seven dogs. Radiographic abnormalities included lung lobe consolidation or pulmonary mass lesions, as well as abnormally large tracheobronchial lymph nodes. Histologic changes included angiocentric and angiodestructive pulmonary infiltrates characterized by large lymphoreticular and plasmacytoid cells as well as normal lymphocytes, eosinophils, and plasma cells. Five dogs were treated with combination chemotherapy, and three had a complete response to treatment.

Alterations in carbohydrate metabolism in canine lymphoma.

Following an overnight fast, blood samples were obtained from 14 dogs with previously untreated lymphoma before and 5, 15, 30, 45, 60, and 90 minutes following an intravenous challenge with 500 mg/kg dextrose. Samples were assayed for glucose, lactate, and insulin concentrations and compared statistically with ten control dogs of similar weight and age undergoing an identical dextrose challenge. Dogs with lymphoma had similar glucose tolerance curves when compared with controls. Lactate concentrations were significantly higher (P less than 0.001) at baseline and all time periods of the glucose tolerance test in dogs with lymphoma when compared with controls. Rise in lactate concentrations over baseline levels in the first 30 minutes of the glucose tolerance test were significantly higher in dogs with lymphoma (P = 0.011). Insulin concentrations were significantly higher (P less than 0.001) at baseline and at the 5-, 45-, 60-, and 90-minute time periods of the glucose tolerance test in dogs with lymphoma. Rise in insulin concentrations over baseline in the first 5 minutes of the glucose tolerance test were also significantly greater in dogs with lymphoma (P = 0.021). These results indicate carbohydrate metabolism is altered in dogs with lymphoma. Many of these alterations parallel those observed in human patients suffering from cancer cachexia making canine lymphoma a potential model for further study of the pathogenesis and therapy of cancer cachexia.

Repeatability of energy expenditure measurements in clinically normal dogs by use of indirect calorimetry.

Energy expenditure (EE) was determined, using an open-flow indirect calorimetry system in a group of 20 clinically normal, apparently resting, client-owned dogs. Five evaluations were performed over an 8-hour period to determine reliability of the method. The intraclass correlation coefficient was calculated as the ratio of within- and between-subject variances, using repeated-measures ANOVA. When only the middle 3 evaluations were included, the intraclass correlation coefficient was 0.87, indicating good reliability. The first evaluation was higher than the subsequent 4 evaluations for rate of O2 consumption (Vo2/kg and Vo2/kg0.75; (P < or = 0.01), and EE/kg and EE/kg0.75 (P < or = 0.005). The respiratory quotients at the first (P = 0.004) and second (P = 0.013) evaluations were different from the respiratory quotient at the fourth evaluation. Therefore, the first evaluation may not be representative of the actual EE. The mean value of at least 3 subsequent evaluations after an adequate adaptation period (5 to 10 minutes) to the equipment will be useful for predicting energy requirements of apparently resting, clinically normal dogs.

Serum concentrations of thyroxine, 3,5,3'-triiodothyronine, thyrotropin, and prolactin in dogs before and after thyrotropin-releasing hormone administration.

Serum concentrations of thyrotropin (TSH), prolactin, thyroxine, and 3,5,3'-triiodothyronine in 15 euthyroid dogs and 5 thyroidectomized and propylthiouracil-treated dogs after thyrotropin-releasing hormone (TRH) administration were measured. Although thyroidectomized and propylthiouracil-treated dogs had higher (P less than 0.01) base-line concentrations of TSH in serum than did euthyroid dogs, concentrations of TSH after TRH administration varied at 7.5, 15, and 30 minutes with 14 of 45 samples obtained from healthy dogs having lower TSH concentrations than before TRH challenge. Similarly, concentrations of 3,5,3'-triiodothyronine in the serum of euthyroid dogs 4 hours after TRH administration were similar (P less than 0.05) to concentrations before TRH challenge. Although the mean concentration of thyroxine in serum was elevated (P less than 0.05) 4 hours after administration of TRH to euthyroid animals, as compared with base-line levels, the individual response was variable with concentrations not changing or decreasing in 4 dogs. Therefore, the TRH challenge test as performed in the current investigation was of limited value in evaluating canine pituitary gland function. Although mean concentrations of TSH in serum were higher (P less than 0.05) in euthyroid dogs after TRH administration, the response was too variable among individual animals for accurate evaluation of pituitary gland function. Concentrations of prolactin in the sera of dogs after TRH administration, confirmed previous reports that exogenously administered TRH results in prolactin release from the canine pituitary and indicated that the TRH used was biologically potent.

Serum concentrations of thyroxine and 3,5,3'-triiodothyronine before and after intravenous or intramuscular thyrotropin administration in dogs.

Response to thyrotropin (TSH) was evaluated in 2 groups of mixed-breed dogs. Thyrotropin (5 IU) was administered IV to dogs in group 1 (n = 15) and IM to dogs in group 2 (n = 15). Venous blood samples were collected immediately before administration of TSH and at 2-hour intervals for 12 hours thereafter. In group 1, the maximum mean concentration (+/- SD) of thyroxine (T4; 7.76 +/- 2.60 micrograms/dl) and 3,5,3'-triiodothyroxine (T3; 1.56 +/- 0.51 ng/ml) was attained at postinjection hours (PIH) 8 and 6, respectively. However, the mean concentration of T4 at PIH 6 (7.21 +/- 2.39 micrograms/dl) was not different (P greater than 0.05) from the mean concentration at PIH 8. The maximum mean concentration of T4 (10.10 +/- 3.50 micrograms/dl) and T3 (2.22 +/- 1.24 ng/ml) in group 2 was attained at PIH 12 and 10, respectively. Because dogs given TSH by the IM route manifested pain during injection, had variable serum concentrations of T3 after TSH administration, and may require 5 IU to achieve maximal increases in serum T4 concentrations, IV administration of TSH is recommended. The optimal sampling time to observe maximal increases in T3 and T4 after IV administration of TSH was 6 hours. Repeat IV administration of TSH may cause anaphylaxis and, therefore, is not recommended.

Continuous positive airway pressure therapy for aspiration pneumonia in a dog.

A 14-year-old mixed-breed dog aspirated a large amount of liquid barium sulfate. Calculation of the alveolar arterial oxygen tension difference (34 mm of Hg; normal, less than 7.5 mm of Hg) from the alveolar gas equation and the arterial blood gas analysis indicated impaired pulmonary gas exchange. The dog was treated for 5 days with continuous positive airway pressure and supplemental oxygen administered by a simple apparatus connected to a tracheostomy tube. Continuous positive airway pressure was believed to improve gas exchange and to increase pulmonary compliance by decreasing alveolar collapse in this dog.

Efficacy and toxicity of estrogens commonly used to terminate canine pregnancy.

Three groups of bitches were treated with diethylstilbestrol (75 micrograms/kg) orally for 7 days (n = 12), estradiol cypionate intramuscularly once (22 micrograms/kg; n = 12), or estradiol cypionate intramuscularly once (44 micrograms/kg; n = 12). Treatments commenced during late proestrus (n = 4/group), the fourth day of behavioral estrus (n = 4/group), or the second day of diestrus (n = 4/group). All bitches were bred on alternate days throughout estrus to stud dogs of known fertility. Ovariohysterectomies were performed on day 25 of diestrus to diagnose pregnancy and to assess any pathologic changes in the uterus. Eleven bitches treated with diethylstilbestrol, 6 bitches treated with the low dosage of estradiol cypionate, and 4 bitches receiving the high dosage of estradiol cypionate were pregnant at the time of surgery. Ten of the bitches treated with estrogens during proestrus, 6 treated during estrus, and 4 treated during diestrus were pregnant. The serum concentration of progesterone in 2 bitches treated with the high dosage of estradiol cypionate decreased to less than 2 ng/ml by day 25 of diestrus, suggesting premature luteal regression. Diethylstilbestrol appeared to have little efficacy in terminating pregnancy. Estradiol cypionate appeared to have greater efficacy when administered during estrus or early diestrus; however, pyometra developed in 2 bitches treated with this estrogen during diestrus.

Tissue preservation for single-tooth anterior esthetics.

Placing implants in the esthetic zone can be difficult because of the expectations of the patient. Inevitably, the hard and soft tissue architecture is lost after extraction in the traditional two-stage procedure, and additional surgical procedures are required to restore the tissue that has been lost. The authors describe techniques that can be applied to retain ideal soft tissue if it is present and predictably restore tissue that is less than ideal.

Randomized, controlled trial of budesonide and prednisone for the treatment of idiopathic inflammatory bowel disease in dogs.

BACKGROUND: Budesonide has been used to treat inflammatory bowel disease (IBD) in dogs, but no controlled studies have been performed to evaluate efficacy of this treatment. OBJECTIVE: To compare budesonide and prednisone for induction therapy of IBD in dogs by using IBD activity index scores and evaluating frequency and severity of owner-reported adverse effects. ANIMALS: Forty client-owned dogs with newly diagnosed idiopathic IBD were enrolled between April 2001 and January 2004; 34 dogs completed the 6 week study. METHODS: Double-blinded, randomized controlled trial. Dogs were randomized to receive either pure powder-based budesonide (3-7 kg: 1 mg PO q24h, 7.1-15 kg: 2 mg PO q24h, 15.1-30 kg: 3 mg PO q24h, >30 kg: 5 mg PO q24h) for 6 weeks or prednisone (1 mg/kg PO q12h × 3 weeks then 0.5 mg/kg PO q12h × 3 weeks). IBD activity index (IBDAI) scores were determined at diagnosis and after 6 weeks of treatment. Pet owners completed weekly questionnaires regarding clinical signs and incidence and severity of adverse effects. RESULTS: Significant differences in remission rates (>75% decrease in IBDAI scores) were not observed with a remission rate of 78% in the budesonide group and 69% in the prednisone group (P = .70). Frequency of adverse effects was similar between the 2 groups. CONCLUSIONS AND CLINICAL IMPORTANCE: There was no demonstrable difference in remission rates or incidence of adverse effects between prednisone and budesonide for induction therapy of IBD in dogs.