Effect of once daily topical 0.3% naltrexone on tear parameters and corneal sensitivity in dogs with uncontrolled keratoconjunctivitis sicca: a double-masked randomized placebo-controlled clinical trial

OBJECTIVE

To determine the effect of once daily topical 0.3% naltrexone (NTX) on tear production, tear film breakup time (TFBUT), and corneal sensitivity in dogs with uncontrolled keratoconjunctivitis sicca (KCS).

ANIMALS STUDIED

Sixteen dogs with uncontrolled KCS.

PROCEDURES

A randomized placebo-controlled trial was performed in 16 dogs with topical 0.3% NTX once daily or topical saline solution drops once daily. A baseline was obtained at week 0 for tear production (Schirmer tear test 1 and 2-STT1, STT2), TFBUT, and corneal sensitivity. STT1, STT2, and TFBUT were then subsequently measured at weeks 1, 2, and 4 while on NTX or saline drops. Corneal sensitivity measures were repeated at week 4. The drops were subsequently discontinued and all parameters rechecked at week 5.

RESULTS

There was no statistically significant difference in tear parameters or corneal sensitivity between the NTX-treated and the saline-treated groups.

CONCLUSION

Topical 0.3% NTX given as a once daily dose over 4 weeks did not alter tear production, tear film stability, or corneal sensitivity in dogs with uncontrolled KCS.

Evaluation of the ocular penetration of topical alpha-luminol (Galavit®/GVT®)

PURPOSE

Oxidative stress plays a major role in the pathogenesis of many neurodegenerative diseases. It has also been implicated as part of the pathogenic mechanisms in the development of glaucoma. Alpha-luminol has shown profound anti-inflammatory and antioxidant effects in both experimental animal and human clinical studies. The purpose of this pilot study was to investigate for the first time the ocular penetration of topical alpha-luminol.

METHODS

Nine animals were divided into three treated groups (three animals each; one drop OU/n = 18), each group receiving a different concentration of the eyedrop (0.5%, 1.5%, 2.5%). Aqueous humor and peripheral blood samples were obtained from each rabbit at three different timepoints (20 min, 4 h and 12 h). Samples were analyzed by means of high performance liquid chromatography and mass spectrometry; median values were compared.

RESULTS

Alpha-luminol was found in the aqueous humor in all treated groups at all timepoints. At the 2nd and 3rd timepoints (4 h and 12 h), aqueous humor levels decreased significantly (P < 0.05) for two of the three dosages tested and it was not detectable in some eyes. The highest aqueous humor concentration of the drug was 272 ng/mL after 20 min (0.0217% of one drop, 2.5% group). Alpha-luminol was found in the vitreous in two animals, one in the 1.5% and another in the 2.5% group (16.4 and 21.5 ng/mL, respectively), at 12 h.

CONCLUSIONS

Topically administered alpha-luminol readily penetrates into the anterior chamber and can penetrate into the vitreous chamber. Further investigation is warranted to better understand the intraocular pharmacokinetics of alpha-luminol.

Histologic evaluation of the immediate effects of diamond burr debridement in experimental superficial corneal wounds in dogs

PURPOSE

To evaluate the corneal changes immediately after diamond burr debridement of superficial corneal wounds in dogs. Spontaneous chronic corneal epithelial defects (SCCEDs) are the most common form of canine recurrent corneal ulcers. The diamond burr has been used in the management of corneal lesions in humans since 1983. Recently, it has been successfully used in the treatment of SCCEDs in dogs; however, little has been documented as to its mechanism of action.

METHODS

Five adult female research dogs euthanized for reasons unrelated to the study were included, providing 10 normal eyes. An excimer laser spatula was used for epithelial removal after delineation with an 8 mm punch biopsy trephine. Diamond burr debridement was performed for 30 and 45 s in five eyes each (groups 1 and 2 respectively). The procedure was performed on the ventral half of the experimental defect as well as ventral normal cornea, immediately after euthanasia, and prior to enucleation. Samples were processed routinely for histologic evaluation and stained with periodic acid-Schiff.

RESULTS

No stromal defects could be identified under light microscopy. In experimental corneal wounds, multi-focal areas remained covered by the epithelial basement membrane (BM) after diamond burr treatment in both groups (group 1 = 48% ± 16SD, group 2 = 26% ± 12SD). Removal of BM on group 2 was significantly higher than group 1 (P < 0.05). CONCLUSIONS : The diamond burr allows a safe method of debridement and does not create defects beyond the epithelial BM in corneal wounds in normal dogs. Evaluation of the diamond burr debridement in cases of SCCEDs is warranted.

Effect of topical ophthalmic application of cidofovir on experimentally induced primary ocular feline herpesvirus-1 infection in cats

OBJECTIVE

To evaluate the efficacy of twice-daily ophthalmic application of 0.5% cidofovir solution in cats with experimentally induced primary ocular feline herpesvirus-1 (FHV-1) infection.

ANIMALS

Twelve 6-month-old sexually intact male cats.

PROCEDURES

Cats were randomly assigned to either a treatment or control group. Ocular infection with FHV-1 was induced (day 0) in all cats via inoculation of both eyes with 10(4) plaque-forming units of a plaque-purified FHV-1 field strain. Twice daily for 10 days beginning on day 4 after virus inoculation, the treatment group received 1 drop of 0.5% cidofovir in 1% carboxymethylcellulose in both eyes, and the control group received 1 drop of 1% carboxymethylcellulose in both eyes. A standardized scoring method was used to evaluate clinical signs of FHV-1 infection in each cat once daily for 24 days. The amount of ocular viral shedding was assessed by use of a quantitative real-time PCR procedure every 3 days during the study period. Clinical scores and viral quantification were averaged over the pretreatment (days 0 to 3), treatment (days 4 to 14), and posttreatment (days 15 to 24) periods for each cat.

RESULTS

During the treatment period, clinical scores and amount of viral ocular shedding were significantly lower in the treatment group, compared with findings in the control group.

CONCLUSIONS AND CLINICAL RELEVANCE

Twice-daily application of 0.5% cidofovir solution in both eyes significantly decreased the amount of viral shedding and the severity of clinical disease in cats with experimentally induced ocular FHV-1 infection.

Prevalence of feline herpesvirus 1, Chlamydophila felis, and Mycoplasma spp DNA in conjunctival cells collected from cats with and without conjunctivitis

OBJECTIVE

To use PCR assays to determine the prevalence of feline herpesvirus 1 (FHV-1), Chlamydophila felis, and Mycoplasma spp DNA in conjunctival cells collected from cats with and without conjunctivitis; to compare results of conventional and real-time fluorogenic PCR assays for amplification of FHV-1 DNA; and to determine whether copy numbers of FHV-1 DNA are correlated with conjunctivitis.

ANIMALS

55 cats with active conjunctivitis, 39 healthy cats that never had conjunctivitis, and 32 cats with a history of conjunctivitis that had been resolved for at least 3 months.

PROCEDURES

Samples were obtained by rolling cotton-tipped applicators on the ventral conjunctiva of awake cats treated topically with proparacaine. The DNA was extracted from the swab specimens and assessed in PCR assays to detect DNA of FHV-1 (fluorogenic PCR assay and conventional PCR assay), Mycoplasma spp (conventional PCR assay), and C felis (conventional PCR assay).

RESULTS

Overall prevalence rates of FHV-1, C felis, and Mycoplasma spp as assessed by the conventional PCR assays were 6.7%, 3.2%, and 9.6%, respectively. Percentage concordance between conventional PCR and fluorogenic PCR assays for FHV-1 was 92.5%. There were no significant differences among the 3 groups of cats for the mean copy number of FHV-1 divided by the copy number of glyceraldehyde-3-phosphate dehydrogenase.

CONCLUSIONS AND CLINICAL RELEVANCE

Mycoplasma spp were the most prevalent organism detected and was associated with conjunctivitis. This study could not confirm that there are increased copy numbers of FHV-1 DNA in cats with conjunctivitis, compared with the copy numbers for cats without conjunctivitis.

Prevalence of serum antibodies against Bartonella species in the serum of cats with or without uveitis

Bartonella henselae has been implicated as a causative agent of chronic uveitis in people and in some cats. The objective of this study was to determine whether Bartonella species seroprevalence or titer magnitude varies among cats with uveitis, cats without ocular diseases recorded and healthy cats, while controlling for age and risk of flea exposure based on state of residence. There was no difference in seroprevalence rates or titer magnitude between cats with uveitis and cats with non-ocular diseases. Healthy cats were more likely to be seropositive for Bartonella species than cats with uveitis. The median Bartonella species titer was 1:64 for all groups, although healthy cats were more likely to have higher titers than cats with uveitis and cats with non-ocular disease. The results suggest that serum antibody tests alone cannot be used to document clinical uveitis associated with Bartonella species infection.

Evaluation of retinal images for identifying individual dogs

OBJECTIVE

To F whether vessels in the ocular fundus changed over the lifetime of Beagles and whether any changes were substantial enough to likely preclude positive identification of individual dogs by use of their retinal vascular patterns.

ANIMALS

18 Beagles.

PROCEDURES

Fundic photographs of both eyes of 18 Beagles taken at 1 or 3, 5, and 7 or 9 years of age were digitalized. Photographs were analyzed by use of 2 software programs. One was used to determine vessel numbers and widths and the other to determine the locations of the 3 largest vessels. Measurements were compared over time periods in the life of each dog. Only observations made at baseline (1 or 3 years of age) and again at 5 and 9 years of age were included in the statistical analysis, as these points were common to all dogs.

RESULTS

No significant changes in numbers or locations of the blood vessels were detected over time. Widths of the vessels decreased significantly as the dogs aged.

CONCLUSIONS AND CLINICAL RELEVANCE

The ocular fundus of Beagles changed over each dog's lifetime in that the retinal blood vessels became smaller but did not change in number or location. Results suggest that digitalized retinal images can likely be used to identify dogs over their lifetimes.

Primary closure of the corneas of two Great Horned owls after resection of nonhealing ulcers

Two Great Horned owls were presented to the Colorado State University Veterinary Teaching Hospital for evaluation of corneal lesions. Each bird had a corneal ulcer and bullous keratopathy. Following unsuccessful attempts at medical and surgical management, the corneal defects in each bird were treated with penetrating keratoplasties and conjunctival pedicle grafts. In each bird the cornea healed well and regained approximately its normal shape. Both birds fully recovered and have been released into the wild.

Depletion of taurine and glutamate from damaged photoreceptors in the retinas of dogs with primary glaucoma

OBJECTIVE

To determine whether taurine and glutamate contents are reduced in damaged photoreceptors in dogs with primary glaucoma (PG) in a manner consistent with an ischemia-like release of both of these amino acids from damaged cells.

SAMPLE POPULATION

Retinas from 6 dogs with PG and 3 control dogs.

PROCEDURE

Serial, semithin sections of each canine retina were stained with toluidine blue to identify damaged photoreceptors or via immunogold techniques to quantify taurine and glutamate content in retinal cells.

RESULTS

Regions with a thin outer nuclear layer and pathologic nuclear changes in photoreceptors were evident in retinas of dogs with PG. The density of immunostaining for taurine in damaged photoreceptors was significantly reduced to (mean +/- SEM) 37.5 +/- 2.6% of the density in adjacent undamaged photoreceptors. Photoreceptors with decreased taurine immunostaining also had decreased glutamate immunostaining, consistent with ischemia-like release of both of these amino acids from damaged cells. Immunostaining for glutamate, but not taurine, was increased in presumptive radial glial cells (i.e., Miller cells) in damaged regions, consistent with an ischemia-induced redistribution of amino acids in dogs with PG.

CONCLUSIONS AND CLINICAL RELEVANCE

Retinal damage in dogs with PG includes ischemia-like losses of taurine and glutamate from photoreceptors and accumulation of glutamate, but not taurine, in nearby Müller cells. These changes are consistent with glutamate release and depletion of intracellular taurine in damaged regions, perhaps contributing to progressive damage in these areas.

Evaluation of glutamate loss from damaged retinal cells of dogs with primary glaucoma

OBJECTIVE

To determine whether retinal damage in dogs with primary glaucoma (PG) is consistent with ischemia-induced glutamate toxicosis.

SAMPLE POPULATION

Retinal tissue sections from 25 dogs with PG and 12 normotensive control dogs.

PROCEDURE

Retinal sections from control and glaucomatous dogs were stained for morphometric and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) analyses to determine whether retinal damage was consistent with glutamate toxicosis. Immunohistochemical analysis was performed to detect ischemia-like loss of glutamate from neurons in damaged areas.

RESULTS

In severely damaged glaucomatous retinas, all neurosensory layers had focal regions that were thin or disrupted. There was less thinning of the outer nuclear layer (ONL) and inner nuclear layer (INL) in moderately damaged retinas than in severely damaged retinas. Acute signs of damage in the INL included cells with dark, condensed chromatin and lightly stained cytoplasm interspersed with a few TUNEL-positive cells, which was consistent with glutamate toxicosis. Glutamate immunoreactivity was reduced in thin areas and in damaged cells of the INL and ONL, which was consistent with glutamate release in damaged areas. Glutamate immunoreactivity was increased in putative Müller cells in damaged areas, which also was consistent with glutamate release.

CONCLUSIONS AND CLINICAL RELEVANCE

Retinal damage in dogs with PG differs in intensity in focal areas. Damage in affected regions resembles damage induced by glutamate. Glutamate is lost from damaged neurons and accumulates in Müller cells, which is consistent with increased glutamate release contributing to the damage. Glutamate antagonists may protect INL cells in dogs with glaucoma.

Idiopathic ocular and nasal granulomatous inflammatory disease in a dog

A young female Akita presented for ocular and nasal lesions. Examination showed bilateral 360 degree limbal masses that extended onto the peripheral cornea. In addition, intranasal granulomatous masses were observed by rhinoscopy. Histopathologic examination with immunohistochemical staining showed that these masses were almost identical and were classified as an idiopathic, T-cell rich, granulomatous inflammation. The dog responded well to anti-inflammatory medication and the disease remains in remission 2 years after the initial presentation.

Ultrasound biomicroscopy of the feline anterior segment

Ultrasound biomicroscopy was performed on enucleated feline globes as a model for use in vivo. Quantitative measurements were obtained from the anterior segment using a 50-MHz transducer. Mean values from 26 feline globes were axial corneal thickness, 0.74 mm; anterior chamber depth, 4.20 mm; distance from the first ciliary process to the limbus, 3.17 mm; angle recess, 0.38 mm; angle opening distance, 1.05 mm; iris base width 0.38 mm; iris middle width 0.52 mm; iris tip width 0.13 mm, and iris-lens overlap, 0.69 mm. Distinctive features of the feline anterior segment include a relatively wide iridocorneal angle and deep anterior chamber.

Comorbidities and exercise capacity in older patients with intermittent claudication

Patients with peripheral arterial disease (PAD) and intermittent claudication often have coronary artery disease (CAD) and other comorbid medical problems. There is a paucity of information on the impact of coexistent medical conditions on exercise capacity and functional status in patients with PAD. This study examined the impact of CAD, diabetes, cigarette smoking, prior peripheral surgical revascularization and other medical conditions on claudication pain times and peak oxygen capacity (VO2) during maximal effort treadmill testing in 119 male outpatient volunteers (ankle-brachial index (ABI) of 0.65 +/- 0.2, mean +/- SEM) with a history of Fontaine Stage II PAD. Smoking status was significantly related to ambulatory function. Current smokers had a lower peak VO2 expressed in l/min than either former or never smokers (ANCOVA adjusted for age, p = 0.003). However, after adjustment for body weight, there was only a trend for a difference in peak VO2 between current (13.2 +/- 0.5 ml/kg per min), former (14.2 +/- 0.4 ml/kg per min) and never (15.4 +/- 1.0 ml/kg per min) smokers (ANCOVA, p = 0.10). Current smokers had a shorter time to onset of claudication pain (p = 0.023) and shorter maximal claudication pain times (p = 0.029) than former or never smokers (p = 0.023). The ABI 1 min after cessation of exercise was also lower in smokers compared to former and never smokers (p = 0.018). There were no significant differences in functional performance measures or time to recovery from maximal claudication pain when patients were categorized on the presence or absence of CAD, diabetes, peripheral revascularization, arthritis, hypertension or dyslipidemia. Therefore, smoking adversely affected exercise capacity in these PAD patients, whereas the presence of CAD, diabetes and other medical problems had a relatively minor impact on exercise capacity. In conclusion, the relatively minor impact of comorbid medical conditions on walking ability in patients with PAD reflects the overwhelming limitation in ambulatory function due to the claudication pain.

Inoculation with Bartonella henselae followed by feline herpesvirus 1 fails to activate ocular toxoplasmosis in chronically infected cats

Infection by Toxoplasma gondii is very common in cats although most remain disease free. The factors that trigger development of uveitis in some cats infected with T gondii have not been elucidated, but infection by more than one organism may be contributory. In this study, cats chronically infected with T gondii were inoculated with Bartonella henselae followed by FHV-1 to test the hypothesis that immune stimulation by multiple infections will reactivate ocular toxoplasmosis. Anterior uveitis and chorioretinitis were not detected in the cats with chronic T gondii infection thus allowing rejection of the hypothesis using this experimental design.

Aqueous misdirection and ciliary block (malignant) glaucoma after cataract removal in a llama

Ciliary block (malignant) glaucoma is caused by the posterior flow of aqueous humor into or behind the vitreous. It is a rare complication of anterior segment surgery in humans. This is a report of ciliary block glaucoma occurring as a postoperative complication of cataract surgery in a llama. Medical management was ineffective in lowering intraocular pressure (IOP). Posterior capsulotomy and anterior hyaloid disruption with a 22-gauge needle, in addition to medical management maintained IOP in the normal range until anterior vitrectomy could be performed. After vitrectomy, glaucoma resolved and medical treatment was no longer necessary.

Treatment of granulomatous meningoencephalomyelitis in a dog

The clinical work-up, diagnosis and follow-up of an 8-year-old, female-spayed Shih Tzu with diffuse, granulomatous meningoencephalomyelitis (GME)-causing visual deficits is reported. The use of cytosine arabinoside as an alternative treatment for GME is discussed.

Detection of Toxoplasma gondii in the milk of experimentally infected lactating cats

Tachyzoites of Toxoplasma gondii have been found in the milk of sheep, goats, cows and mice and infection by ingestion of raw goat milk has been documented in humans. Lactational transmission from infected cats to their kittens is suspected but the organism has not been detected in the milk. The purpose of this study was to demonstrate the presence of T. gondii in the milk of experimentally infected cats. Pregnant specific pathogen free cats were inoculated orally with T. gondii at various times prior to parturition. Feces were examined for oocyst shedding after sugar solution centrifugation. Milk was collected for polymerase chain reaction (PCR) and bioassay in mice. T. gondii was detected in the milk of five of six cats by either bioassay or PCR.

Analysis of aqueous humor obtained from normal eyes of llamas and alpacas

OBJECTIVE

To evaluate composition of aqueous humor obtained from normal eyes of llamas (Lama glama) and alpacas (Lama pacos).

SAMPLE POPULATION

Aqueous humor obtained from 10 male llamas and 10 male alpacas.

PROCEDURE

All animals had normal eyes, as determined by ocular examination. Aqueous humor samples were obtained via paracentesis of the anterior chamber of animals that were heavily sedated. Chemical analysis included measurement of concentrations of sodium, potassium, magnesium, chloride, bicarbonate, phosphorus, and glucose as well as osmolality and pH.

RESULTS

With the exception of potassium concentrations, values for aqueous humor composition did not differ significantly between llamas and alpacas. Mean +/- SD values for llamas and alpacas, respectively, were: sodium, 154.7 +/- 2.1 and 152.7 +/- 2.1 mEq/L; potassium, 5.3 +/- 0.4 and 4.6 +/- 0.4 mEq/L; magnesium, 1.8 +/- 0.1 and 1.7 +/- 0.1 mg/dl; chloride, 130.0 +/- 1.6 and 127.0 +/- 3.3 mEq/L; bicarbonate, 19.2 +/- 1.5 and 20.2 +/- 2.3 mEq/L; phosphorous, 2.7 +/- 0.3 and 2.5 +/- 0.4 mg/dl; glucose, 80.3 +/- 3.9 and 80.8 +/- 7.3 mg/dl; total protein, 29.0 +/- 8.6 and 31.5 +/- 10.1 mg/dl; and osmolality, 305.8 +/- 11.8 and 306.2 +/- 4.9 mOsm. The pH ranged from 7.5 to 8.0 for both species. Potassium concentrations were significantly higher in llamas than alpacas.

CONCLUSIONS AND CLINICAL RELEVANCE

Except for potassium, composition of aqueous humor did not differ significantly between llamas and alpacas. Aqueous humor composition of llamas and alpacas is similar to that of other species that have been examined.

Clinical ocular toxoplasmosis in neonatal kittens

OBJECTIVE

To describe ocular findings in kittens with congenital or early neonatal infection by Toxoplasma gondii and to determine if there are detectable differences in disease caused by three strains.

ANIMALS STUDIED

Six adult female cats and the offspring from seven litters.

METHODS

Four kittens from uninfected specific pathogen-free (SPF) queens and 21 kittens from SPF queens inoculated at various times late in gestation with Mozart, Maggie, or ME-49 strain of T. gondii were used. Ocular examinations were performed on queens prior to and after delivery, and on kittens weekly to bi-weekly for up to 27 weeks. Whole blood for serology was collected from all kittens at 5(1/2) to 8 weeks of age and again at 12 weeks of age or later.

RESULTS

No kittens from noninfected queens developed ocular lesions or antibody to T. gondii. Three of the 24 kittens from infected queens died or were euthanized early in the study. Chorioretinitis was detected in 15 of 21 living kittens from infected queens. Two developed concurrent anterior uveitis that resolved within 1 week. Posterior segment lesions varied ophthalmoscopically between strains. Of 21 kittens from T. gondii-infected queens, six developed positive antibody titers to T. gondii during the study. All seropositive kittens were born to queens infected with Mozart strain of T. gondii.

CONCLUSION

Results of this study suggest that ocular toxoplasmosis can occur without other evidence of clinical illness in kittens infected in utero or in the neonatal period, and that T. gondii strains may have varying degrees of ocular pathogenicity in cats.

Effects of exercise rehabilitation on cardiovascular risk factors in older patients with peripheral arterial occlusive disease

OBJECTIVE

The purpose of this study was to determine whether a 6-month exercise rehabilitation program can improve cardiovascular risk factors in patients with peripheral arterial occlusive disease (PAOD).

METHODS

Thirty-four patients (mean age, 68 +/- 8 years; range 54-84 years) with PAOD with intermittent claudication (Fontaine stage II) and 14 longitudinal controls of comparable age with stage II PAOD enrolled in an exercise intervention at the University Medical Center and Veterans Affairs Medical Center at Baltimore, Maryland. The main outcome measures were lipid profile (total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol [LDL-C]), fasting glucose, blood pressure, body mass index, treadmill times to onset and maximal claudication pain, cardiopulmonary function (peak oxygen uptake), and ankle/brachial index.

RESULTS

With exercise rehabilitation, treadmill times to onset and maximal claudication pain increased by 106% and 64% (P <.0001), whereas peak oxygen uptake increased 7% (P <.05). Exercise rehabilitation lowered total cholesterol and LDL-C levels by 5.2% (P <.005) and 8% (P <.01), respectively. Systolic blood pressure declined by 5.7% (P <.05) with no change in diastolic blood pressure. These changes in cholesterol and LDL-C concentrations were related to their initial values. All other cardiovascular risk factors measured did not change. There was no correlation between improvement of cardiovascular risk factors and functional performance measurements. None of the variables measured changed significantly in the control group.

CONCLUSIONS

Exercise rehabilitation not only improves functional performance, but also results in favorable alterations in cardiovascular risk factor profile, which is an important element in the management of PAOD.

A new device to limit extravasation during contrast-enhanced CT

OBJECTIVE

The extravasation detection accessory (EDA) is designed for use during contrast-enhanced CT studies performed with a power injector. The EDA detects the changes in soft-tissue impedance that occur with enhanced extravasation and halts the further infusion of contrast material via a feedback circuit to the injector. We tested the sensitivity of this device in a model of contrast extravasation.

MATERIALS AND METHODS

Study subjects had an extravasation of 5% dextrose in water (nonionic contrast equivalent) in one arm and 0.9% sodium chloride solution (ionic contrast equivalent) in the other. An EDA was placed over the site of infusion and connected to a power injector. Injections were performed at 0.25 ml/sec (n = 40), 2.5 ml/sec (n = 62), or 5 ml/sec (n = 20).

RESULTS

At infusion rates of 2.5 and 5 ml/sec, the device halted the injector in every subject after an average volume of 12.5 +/- 1.6 ml was delivered. At 0.25 ml/sec, the device failed to halt the injector in 11 of 20 events. After reprogramming the algorithm, 10 more subjects were tested at the lowest injection rate. The device halted 18 of 20 extravasation events with an average volume of 3.7 +/- 0.5 ml.

CONCLUSION

In our model of contrast extravasation, the EDA halted a power injector with reliability and reproducibility before a large volume of contrast material was delivered. The sensitivity of the device approached, but did not reach, 100%. This device may serve to diminish the morbidity of extravasation events.

Chronic venous insufficiency is associated with increased platelet and monocyte activation and aggregation

PURPOSE

This study assessed whether the increased numbers of platelet-monocyte aggregates observed in patients with venous stasis ulceration (VSU) represent a response to dermal ulceration or if it is a condition associated with underlying chronic venous insufficiency (CVI). We also analyzed the expression of CD11b in patients with CVI to determine whether leukocyte activation, known to occur in VSU, is a precursor of or a response to ulceration.

METHODS

Patients with varying classes of CVI (n = 24) and healthy control subjects (n = 15), whose status was documented by means of duplex scanning, stood upright and stationary for 10 minutes. Two aliquots of blood, drawn from a distal leg vein and an antecubital fossa vein, were incubated with either buffer or one of three platelet agonists. After fixation, these samples were further incubated with fluorescent-labeled monoclonal antibodies (f-MoAb) specific for CD14 (monocytes) and CD61 (platelets). The activated leukocyte assay was performed by incubating another aliquot of the blood samples with f-MoAb specific for CD11b and CD14. All samples were evaluated by means of flow cytometry.

RESULTS

We observed significantly more platelet-monocyte aggregates throughout the circulation in patients with CVI than in control subjects (29% vs. 8%; P <.0002). Furthermore, patients with CVI formed significantly more of these aggregates in response to all platelet agonists than did control subjects. There were no significant differences between baseline numbers of aggregates or response to agonists in patients who had CVI with (n = 10) or without (n = 14) ulceration. Patients with CVI had more circulating platelet-neutrophil aggregates than control subjects (7.2% vs. 3.6%; P =.05). The addition of platelet agonists to the blood of patients with CVI resulted in more platelet-neutrophil aggregates than in control subjects. Monocyte CD11b expression was higher in patients with CVI than in control subjects (7.5 vs. 3.7; P <.01), with no differences noted in CD11b expression between patients with or without ulceration. Neutrophil CD11b expression was low and similar in control subjects and patients with CVI.

CONCLUSION

All classes of CVI are associated with significantly increased percentages of platelet-monocyte aggregates and increased percentages of platelet-neutrophil aggregates throughout the circulation. The presence of more of these aggregates and the increased propensity to form aggregates in the presence of platelet agonists in all classes of CVI suggests an underlying state of platelet activation and increased reactivity that is independent of the presence of ulceration. The increased expression of monocyte CD11b throughout the circulation in all classes of CVI suggests that although systemic monocyte activation occurs in CVI, its presence is independent of VSU as well.

The prevalence of carotid artery stenosis in patients undergoing aortic reconstruction

BACKGROUND

Coronary artery disease occurs frequently in patients undergoing aortic reconstruction, and it has been presumed that internal carotid artery occlusive disease is also common. This has led to the practice of screening for and repairing significant carotid lesions in asymptomatic patients prior to aortic reconstruction. The purpose of this study was to determine the true prevalence of internal carotid artery disease in these patients.

METHODS

The records of 240 patients who underwent duplex ultrasound screening for carotid artery disease prior to aortic reconstruction were reviewed. Surgery was performed for aortic aneurysm (AA) or aorto-iliac occlusive disease (AO). The prevalence of hyperlipidemia and coronary artery disease was similar between the two groups, but tobacco use, hypertension, and diabetes mellitus differed.

RESULTS

Internal carotid artery stenosis > or = 50% occurred in 26.7% of the total group (64 of 240 cases). Stenosis > or = 50% was more common in the AO group (40 of 101 cases, 39.6%) than the AA group (24 of 139 cases, 17.3%, P = 0.0001). Severe disease (70% to 99%) was also more common in the AO group than the AA group (9.9% versus 3.6%, P = 0.0464).

CONCLUSION

Internal carotid artery disease occurs commonly in patients undergoing aortic reconstruction, and screening is worthwhile. Significant disease is more common in patients with aorto-iliac occlusive disease than in those with aortic aneurysm, although atherosclerotic risk factors occur with varying frequency in the two groups. These findings suggest that additional factors may contribute to the higher prevalence of internal carotid artery stenosis in aorto-iliac occlusive disease.

Sequencing and characterization of the citrus weevil, Diaprepes abbreviatus, trypsin cDNA. Effect of Aedes trypsin modulating oostatic factor on trypsin biosynthesis

Trypsin mRNA from the citrus weevil, Diaprepes abbreviatus, was reverse transcribed and amplified by PCR. A cDNA species of 513 bp was cloned and sequenced. The 3' and 5' ends of the gene (262 bp and 237 bp, respectively) were amplified by rapid amplification of cDNA ends, cloned and sequenced. The deduced sequence of the trypsin cDNA (860 bp) encodes for 250 amino acids including 11 amino acids of activation and signal peptides and exhibited 16.8% identity to trypsin genes of selected Lepidoptera and Diptera. A three-dimensional model of Diaprepes trypsin contained two domains of beta-barrel sheets as has been found in Drosophila and Neobellieria. The catalytic active site is composed of the canonical triad of His41, Asp92 and Ser185 and a specificity pocket occupied by Asp179 with maximal activity at pH 10.4. Southern blot analysis indicated that at least two copies of the gene are encoded by Diaprepes midgut. Northern blot analysis detected a single RNA band below 1.35 kb at different larval ages (28-100 days old). The message increased with age and was most abundant at 100 days. Trypsin activity, on the other hand, reached a peak at 50 days and fell rapidly afterwards indicating that the trypsin message is probably regulated translationally. Feeding of soybean trypsin inhibitor and Aedes aegypti trypsin modulating oostatic factor affected trypsin activity and trypsin biosynthesis, respectively. These results indicate that Diaprepes regulates trypsin biosynthesis with a trypsin modulating oostatic factor-like signal.

Adenosine A2a receptors increase arterial endothelial cell nitric oxide

BACKGROUND

Adenosine is a potent vasodilator of vascular smooth muscle. Endothelium-derived nitric oxide (NO) elicits vasodilation. We have previously reported that adenosine stimulates the production of NO from porcine carotid arterial endothelial cells (PCAEC) via a receptor-mediated mechanism. This study was to determine whether adenosine also enhances NO production from human arterial endothelium and to define the involvement of adenosine A1 and A2 receptors.

MATERIALS AND METHODS

Human iliac arterial endothelial cells (HIAEC) and PCAEC were harvested and cultured in dishes. NO production was evaluated with a NO electrode sensor which measured continuously real-time NO production.

RESULTS

NO content of the medium bathing HIAEC and PCAEC was significantly increased with adenosine (100 micromol/L). Ethylcarboxamidoadenosine (NECA), a nonselective adenosine receptor agonist, and carboxyethyl-phenethylamino-ethylcarboxamidoadenosine (CGS-21680), a selective adenosine A2a receptor agonist, increased NO production by HIAEC and PCAEC with respective EC50 values of 3.32 and 6.96 nmol/L for NECA and 30.97 and 29.47 nmol/L for CGS-21680. Chlorofuryl-triazolo-quinazolinamine (CGS-15943; 1 micromol/L), an adenosine A1 and A2 receptor antagonist, and aminofuryltriazolotriazinyl-aminoethylphenol (ZM-241385; 1 micromol/L), a selective adenosine A2a receptor antagonist, inhibited the effect of CGS-21680. Chlorocyclopentyl-adenosine (CCPA; 1 micromol/L), an adenosine A1 receptor agonist, significantly depressed NO production by both HIAEC and PCAEC: This effect was inhibited by cyclopentyl-dipropylxanthine (DPCPX), a selective adenosine A1 receptor antagonist.

CONCLUSIONS

The results demonstrate that adenosine A2a receptors increase, and adenosine A1 receptors decrease, the production of NO by human and porcine arterial endothelial cells.

Diaspirin crosslinked hemoglobin (DCLHb): more effective than lactated Ringer's solution in restoring central venous oxygen saturation after hemorrhagic shock in rats

Central venous oxygen saturation (ScvO2) has been shown to reflect tissue oxygen consumption in hemorrhagic shock. The purpose of this study was to test whether the "blood substitute" diaspirin crosslinked hemoglobin (DCLHb, Baxter Healthcare, Round Lake, IL) might be more effective than lactated Ringer's solution (LR) at restoring tissue oxygenation, as measured by ScvO2, when used as a resuscitative fluid following hemorrhage. Conscious male Sprague-Dawley rats (250-350 gm) were bled through a jugular venous catheter to a target central venous base deficit of 15 +/- 2 mmol/L. Animals were immediately resuscitated with either 10% DCLHb (1:1) or LR (3:1), based on shed blood volume, followed by a maintenance infusion of LR until completion of the experiment. Central venous blood was sampled at baseline, prior to resuscitation and every 15 minutes for the first hour following resuscitation. While the baseline and pre-resuscitation ScvO2 values were not significantly different between groups, ScvO2 values were greater (P < or = 0.01) in the DCLHb group at all times following resuscitation. Furthermore, DCLHb restored SvO2 to baseline by 15 minutes after resuscitation, whereas LR resuscitation never restored ScvO2 to baseline. Since venous desaturation is one of the major compensatory mechanisms by which oxygen consumption is maintained under conditions of limited oxygen supply, these data suggest that animals resuscitated with DCLHb had a more rapid restoration of tissue oxygenation than those resuscitated with LR in this model of hemorrhagic shock.

Subcutaneous oxygen tension: a useful adjunct in assessment of perfusion status

OBJECTIVES

Using a new fluorescence-quenching optode which, unlike earlier oximeters, neither consumes oxygen nor generates heat, we sought to determine the effects of hemorrhage and resuscitation on subcutaneous PO2. Additionally, we compared the effects of resuscitation with diaspirin crosslinked hemoglobin, an oxygen-carrying solution, on subcutaneous PO2 to that of traditional resuscitative fluids. We also compared mean arterial pressure and central venous oxygen saturation, indirect indices of perfusion, to subcutaneous PO2, a direct index of perfusion.

DESIGN

Prospective trial, randomized for selection of treatment regimen.

SETTING

Shock-trauma laboratory of a medical university.

SUBJECTS

Male Sprague-Dawley rats, weighing 260 to 380 g.

INTERVENTIONS

Rats were bled 22 mL/kg and resuscitated, 1 min later, with either 66 mL/kg of lactated Ringer's solution, 22 mL/kg of human serum albumin, 22 mL/kg of blood, or 22 mL/kg of diaspirin crosslinked hemoglobin. A fifth group of animals was not resuscitated after hemorrhage. Subcutaneous PO2 and mean arterial pressure were monitored continuously throughout the experiment, while central venous oxygen saturation was measured intermittently.

MEASUREMENTS AND MAIN RESULTS

Subcutaneous PO2 decreased in response to hemorrhage and, although it did increase after resuscitation with each fluid, no treatment was able to restore subcutaneous PO2 to baseline within 2 hrs postresuscitation. Subcutaneous PO2 continued to decrease after hemorrhage in the unresuscitated animals. In contrast, mean arterial pressure was restored to baseline values in only blood- and diaspirin crosslinked hemoglobin-treated animals, although this effect was lost within 30 mins in the blood-treated group. Only blood restored the central venous oxygen saturation to baseline values in the early postresuscitation period.

CONCLUSIONS

The fluorescence-quenching optode consistently followed changes in subcutaneous PO2 during hemorrhage and after resuscitation. Diaspirin crosslinked hemoglobin performed as well as blood in restoring peripheral perfusion, as measured by subcutaneous PO2, while both of these fluids were superior to either lactated Ringer's solution or albumin. Both whole blood and diaspirin crosslinked hemoglobin restored mean arterial pressure to baseline, although the effect of the latter was of a longer duration. The pressor effect of the crosslinked hemoglobin did not affect peripheral perfusion, as reflected by the values for subcutaneous PO2. Subcutaneous PO2 is a useful adjunct in assessment of the adequacy of peripheral perfusion and may help redefine targets for resuscitation.

Diaspirin crosslinked hemoglobin (DCLHb) attenuates bacterial translocation in rats

Intestinal barrier function is compromised following severe hemorrhage which may allow bacterial translocation (BT) to occur and subsequently initiate a systemic response leading to multiple system organ failure (MSOF). This study compared BT following hemorrhage and resuscitation with lactated Ringer's solution (LR) or diaspirin crosslinked hemoglobin solution (DCLHb). Rats (250-350 grams) were hemorrhaged to a base deficit of 15 +/- 2 mmol/L and immediately resuscitated with either 3:1 LR or 1:1 DCLHb based on shed blood volume. Four hours following resuscitation, the mesenteric lymph node complex was harvested, homogenized and plated onto MacConkey and Columbia CNA agar culture media. Facultative anaerobic and obligate aerobic bacteria were identified 48 hours later in 11/22 (50%) LR-treated rats and in 4/21 (19%) DCLHb-treated rats (p < or = 0.05). Following resuscitation, base excess (BE) and central venous oxygen saturation (SvO2) were not only restored to baseline but were significantly greater (p < or = 0.05) in DCLHb-treated rats than in LR-treated rats. In a separate group of rats subjected to the same hemorrhage and resuscitation protocol, mean arterial pressure in DCLHb-treated rats, but not LR-treated rats, was restored to baseline by 15 minutes and remained at or above baseline for up to 4 hrs. Twenty-four hour survival was 50% in LR-treated rats and 77% in DCLHb-treated rats (p > 0.05). These data suggest that DCLHb is superior to LR in restoring tissue oxygen delivery, as judged by BE and SvO2. Furthermore, since DCLHb restores oxygen delivery and attenuates BT, early resuscitation with DCLHb may limit gut ischemia and subsequent gut barrier failure and hence prevent the development of sepsis, MSOF and subsequent death.

The efficacy of diaspirin crosslinked hemoglobin solution resuscitation in a model of uncontrolled hemorrhage

Controversy exists whether early aggressive fluid therapy in the setting of uncontrolled hemorrhage worsens outcome by increasing blood loss from injured vessels. Since diaspirin crosslinked hemoglobin (DCLHb) is a vasoactive, oxygen-carrying solution, we compared the effects of DCLHb with other resuscitative fluids on blood loss, hemodynamics, and tissue oxygen delivery in a model of uncontrolled hemorrhage. Anesthetized rats (250-350 g) were subjected to a 50% tail transection and resuscitated 15 minutes later with 1:1 DCLHb, 3:1 lactated Ringer's solution (LR), 1:1 hypertonic saline (7.5% HTS), or 1:1 human serum albumin (8.3% HSA) based on initial volume of blood loss (average 4.7 +/- 0.3 mL/kg). An unresuscitated group served as a control. Cumulative blood loss was measured at 5 hours postresuscitation. By 15 minutes after tail transection, mean arterial pressure (MAP) decreased 19.2 +/- 3.8 mm Hg from the baseline value (102 +/- 5 mm Hg). The DCLHb solution restored and maintained MAP and subcutaneous tissue oxygen tension at baseline values better than all other resuscitative fluids. Although blood loss in DCLHb-treated animals was greater than in unresuscitated animals, it was no different from other resuscitative fluids and less than with HSA. There was no difference in 24-hour survival between all treatment groups. In conclusion, DCLHb elevates MAP but does not exacerbate blood loss or compromise tissue oxygen delivery compared with other resuscitative fluids in this model of uncontrolled hemorrhage.

Toxoplasma gondii-specific antibodies in the aqueous humor of cats with toxoplasmosis

We decided to determine whether Toxoplasma gondii-specific IgM or IgG is produced locally or is deposited in the aqueous humor of T gondii-naive cats after primary or secondary inoculation with T gondii. Cats were orally inoculated with T gondii tissue cysts during weeks 0 and 36. Aqueous humor and serum T gondii-specific IgM and IgG were measured, using ELISA, during weeks 0, 2, 4, 6, 8, 12, 16, 20, 26, 34, 38, 40, 42, 44, 48, 56, 62, 66, and 72 after primary oral inoculation. Total immunoglobulin-based Goldmann-Witmer coefficients were calculated to verify intraocular antibody production. Toxoplasma gondii-specific IgM was not detected in the aqueous humor of any cat. Data indicate that cats have transient local production of T gondii-specific IgG in the aqueous humor after primary and secondary oral inoculations with T gondii tissue cysts. The intraocular immune response to systemic T gondii infection may signal ocular recruitment of antigen-specific lymphocytes that function independently from the general humoral response to T gondii infection. Cautious interpretation of results that suggest intraocular production of T gondii-specific IgG in cats with uveitis is warranted.

Detection of Toxoplasma gondii antigen-containing immune complexes in the serum of cats

Enzyme-linked immunosorbent assays for the detection of Toxoplasma gondii antigen-containing IgM immune complexes (T gondii-specific IgM-IC) and IgG immune complexes (T gondii-specific IgG-IC) in the serum of cats were developed. Serum from clinically ill, naturally infected cats; healthy, naturally infected cats; and healthy cats experimentally inoculated with T gondii was assayed. All combinations of T gondii-specific IgM, IgG, antigens, IgM-IC, and IgG-IC were detected in naturally infected and experimentally infected cats. Clinically ill cats and cats with ocular signs of toxoplasmosis were more likely than healthy cats to have T gondii-specific IC in serum. It was concluded that T gondii-specific IC form in the serum of cats, may play a role in clinical disease development, and affect the results of T gondii-specific IgM, IgG, and antigen serologic assays.

Effect of feline immunodeficiency virus infection on Toxoplasma gondii-specific humoral and cell-mediated immune responses of cats with serologic evidence of toxoplasmosis

Serum samples from 89 cats with serologic evidence of toxoplasmosis were identified by using an enzyme-linked immunosorbent assay (ELISA) that detected Toxoplasma gondii-specific immunoglobulin M (IgM) or T. gondii-specific immunoglobulin G (IgG). Concurrent feline immunodeficiency virus (FIV) infection was detected in 36 cats using an ELISA for detection of FIV-specific IgG. The majority of the cats in both the FIV-seropositive and FIV-seronegative groups were male and > 5 years of age. FIV-seropositive cats were more likely to have T. gondii IgM titers without IgG (P < 0.05) or any T. gondii IgM titer (P < 0.05) than were FIV-seronegative cats. FIV-seronegative cats (1328) had a higher T. gondii IgG geometric mean titer than did FIV-seropositive cats (724) and were more likely to have T. gondii IgG titers > 1:2048 than were FIV-seropositive cats (P < 0.05). Cats with serologic evidence of both T. gondii and FIV infections had persistent T. gondii IgM titers for > 12 weeks. Lymphoblast transformation in response to concanavalin A, T. gondii-specific intracellular antigens, and T. gondii-specific secretory antigens was compared in T. gondii seropositive and FIV-seronegative cats, cats with serologic evidence of T. gondii infection alone, and cats with serologic evidence of concurrent FIV and T. gondii infections. Lymphocytes from all but one cat in the FIV-seropositive group responded to concanavalin A. Whereas lymphocytes from FIV-seronegative cats with serologic evidence of toxoplasmosis responded to T. gondii-specific antigens, four of five of the FIV-seropositive cats with concurrent serologic evidence of toxoplasmosis did not.

Effect of primary phase feline immunodeficiency virus infection on cats with chronic toxoplasmosis

The effect of primary phase feline immunodeficiency virus (FIV) infection on clinical signs, hematological values, Toxoplasma gondii oocyst shedding, T. gondii-specific serology, T. gondii-specific cell-mediated immune responses, non-specific cell-mediated immune responses, and lymphocyte subpopulations from cats with experimentally induced chronic toxoplasmosis was studied. No significant clinical or hematologic abnormalities were noted following inoculation with FIV. T. gondii-specific IgM was significantly increased, concanavalin A, T. gondii tachyzoite antigen and T. gondii secretory antigen induction of lymphocyte transformation were significantly suppressed, and CD4+ cell numbers were significantly decreased following inoculation with FIV. The changes were attributed to FIV effects on the immune system and resultant activated toxoplasmosis.

Serologic prevalence of selected infectious diseases in cats with uveitis

Serologic evidence of infection by Toxoplasma gondii, feline leukemia virus, feline coronaviruses, or feline immunodeficiency virus (FIV) is commonly found in cats with uveitis. Serum samples from 124 cats with uveitis were assayed by use of ELISA for the detection of T gondii-specific immunoglobulin M (IgM), IgG, and circulating antigens (Ag), as well as an ELISA for feline leukemia virus Ag, an ELISA for antibodies to FIV, and an indirect fluorescent antibody assay for antibodies to feline coronaviruses. Serologic evidence of infection by 1 or more of the infectious agents was detected in 83.1% of the samples. Serologic evidence of T gondii infection, defined as the detection of T gondii-specific IgM, IgG, or Ag in serum, was found in 74.2% of the samples. The seroprevalence of T gondii infection was significantly greater in cats with uveitis than in healthy cats from a similar geographic area. Serum samples from cats with serologic evidence of both T gondii and FIV infections were more likely to contain T gondii-specific IgM without IgG than samples from cats with serologic evidence of T gondii infection alone. Cats with serologic evidence of FIV and T gondii coinfection had a higher T gondii-specific IgM titer geometric mean and a lower T gondii-specific IgG titer geometric mean than did cats with serologic evidence of T gondii infection alone. Serologic evaluation for T gondii infection should include assays that detect IgM, IgG, and Ag, particularly in cats coinfected with FIV.

Enzyme-linked immunosorbent assays for the detection of Toxoplasma gondii-specific antibodies and antigens in the aqueous humor of cats

Serum and aqueous humor samples, collected from 14 clinically normal cats and 96 cats with clinical evidence of intraocular inflammation, were assayed with ELISA for Toxoplasma gondii-specific immunoglobulin M (IgM), T gondii-specific IgG, T gondii-specific antigens, total IgG, and total IgM. Additionally, serum was assayed with ELISA for feline leukemia virus p27 antigen and antibodies against the feline immunodeficiency virus as well as with an immunofluorescent antibody assay for antibodies against feline coronaviruses. Calculation of the Goldmann-Witmer coefficient (C-value) for the T gondii-specific antibodies detected in aqueous humor established the likelihood of local antibody production. Serologic evidence of present or prior infection by an infectious agent was found in 81.9% of the clinically affected cats from which serologic results were available (77/94 cats). Seropositive results for toxoplasmosis were found in 74.0% of the clinically affected cats. Anterior segment inflammation was found in 93.1% (81/87 cats from which information was available) of the clinically affected cats, most of which were older males. Toxoplasma gondii-specific antibodies were not detected in the aqueous humor of 6 seropositive, clinically normal cats. The C-values for aqueous T gondii antibodies were greater than 1 in 44.8% of the cats and greater than 8 in 24.0% of the cats. Response to treatment with clindamycin HCl was positive in 15/20 (75%) of the T gondii-seropositive, clinically affected cats treated with this drug. In 13/15 (86.7%) T gondii-seropositive, clinically affected cats having a C-value greater than 1, response to treatment with clindamycin HCl was positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of latex agglutination, indirect hemagglutination, and ELISA techniques for the detection of Toxoplasma gondii-specific antibodies in the serum of cats

The primary purpose of this study was to determine whether commercially available latex agglutination and indirect hemagglutination kits for the detection of Toxoplasma gondii-specific antibodies were capable of detecting T. gondii-specific immunoglobulin M (IgM) in the serum of cats. Serum samples from 35 cats containing either T. gondii-specific IgM, T. gondii-specific immunoglobulin G (IgG), or both were collected. Each serum sample was assayed using a latex agglutination kit, an indirect hemagglutination kit, an enzyme-linked immunosorbent assay (ELISA) for the detection of T. gondii-specific IgG, and an ELISA for the detection of T. gondii-specific IgM. When serum samples containing only T. gondii-specific IgM as determined by ELISA were assayed, the latex agglutination kit and the indirect hemagglutination kit detected antibodies in 33.3% and 13.3%, respectively. When T. gondii-specific IgG was present in a serum sample, the results from the latex agglutination kit, the indirect hemagglutination kit, and the IgG-ELISA were similar; however, there was a wide variation in titer magnitude results between the three assays. It was concluded that the latex agglutination kit and the indirect hemagglutination kit did not adequately detect T. gondii-specific IgM in feline serum.

Distribution of cholinergic and adrenergic nerve fibers in the lacrimal glands of dogs

The distribution of postganglionic autonomic nerve fibers in the lacrimal gland and gland of the third eyelid of dogs was studied by use of histochemical techniques. Adrenergic nerve distribution was identified by use of the sucrose-potassium phosphate-glyoxylic acid technique. A loose network of adrenergic nerves was found throughout the interstitium around acini and blood vessels and in vessel walls. Acetylcholinesterase staining was used to identify cholinergic nerve fibers. A cholinergic distribution pattern was found, although the cholinergic innervation appeared more dense than the adrenergic. In the gland of the third eyelid, mucus-secreting lobules and lipid-secreting lobules appeared to be equally innervated by parasympathetic fibers. These lobules could not be differentiated when the sucrose-potassium phosphate-glyoxylic acid technique was used. The techniques used in this study could not demonstrate whether direct contact was made by either cholinergic or adrenergic nerve fibers with secretory or myoepithelial cells. The presence of both nerve fiber types around acini suggests an interrelationship between the sympathetic and parasympathetic nervous system in lacrimal gland secretion in dogs.

Synapse formation and modification between distal retinal neurons in larval and juvenile Xenopus

A serial section analysis of photoreceptor synaptic bases was undertaken in the clawed frog Xenopus laevis. The developmental period from tadpole stage 48 through metamorphosis was studied. Horizontal cells contacted rod and cone photoreceptors at ribbon synapses; the number of such contacts per receptor base was constant for rods, but increased for cones as a function of developmental stage. In pre-metamorphic animals bipolar cells contacted receptors only through basal junctions; their number in cone bases increased dramatically during development but was unchanged in rod bases. A densitometric estimation of the cleft width of basal junctions showed that it ranged from 10 to 18 nm, but the junctions could not be divided reliably into the 'wide' and 'narrow' categories reported for other vertebrate species. Near metamorphic climax a new type of ribbon-related bipolar cell junction appeared. Gap junctions between horizontal cells and conventional synapses of horizontal cell onto bipolar cell processes were first seen in mid-larval developmental stages.