A lateral surgical approach to the larynx may impair cervical esophageal function in dogs

OBJECTIVE

To determine whether muscle-sparing laryngoplasty results in fewer changes in swallowing function compared to standard surgical treatment for laryngeal paralysis.

ANIMALS

12 clinically normal sexually intact male Beagles.

PROCEDURES

Group A dogs (n = 4) had a standard approach to the larynx, with left arytenoid cartilage lateralization. Group B dogs (n = 4) had a muscle-sparing laryngoplasty performed with the thyropharyngeus muscle fibers bluntly separated, and the cricoarytenoideus dorsalis muscle spared. Pre- and 24-hour postoperative fluoroscopic swallowing studies were performed and graded. Larynges were harvested after humane euthanasia, and glottic area was measured. Group C dogs (n = 4) acted as controls, with surgical dissection ending lateral to the thyropharyngeus muscle, arytenoid lateralization not performed, and the dogs not euthanized. The study was performed between October 15, 2011 and May 15, 2021.

RESULTS

Changes in pharyngeal and upper esophageal sphincter function were not detected in any group. There was no difference in glottic area between treatment groups. Aspiration of liquid was not a consistent finding. Two dogs in each treatment group developed moderate to severe cervical esophageal paresis. This did not occur in control dogs.

CLINICAL RELEVANCE

We found no evidence to support our hypothesis that muscle-sparing laryngoplasty results in less severe changes in swallowing function compared to a standard technique. The cervical esophageal paresis identified in both treatment groups could increase the risk of postoperative aspiration pneumonia in dogs treated for laryngeal paralysis via a lateral approach to the larynx. Further study to determine the frequency, cause, and duration of esophageal dysfunction is warranted.

Evaluation of 3D Additively Manufactured Canine Brain Models for Teaching Veterinary Neuroanatomy

Physical specimens are essential to the teaching of veterinary anatomy. While fresh and fixed cadavers have long been the medium of choice, plastinated specimens have gained widespread acceptance as adjuncts to dissection materials. Even though the plastination process increases the durability of specimens, these are still derived from animal tissues and require periodic replacement if used by students on a regular basis. This study investigated the use of three-dimensional additively manufactured (3D AM) models (colloquially referred to as 3D-printed models) of the canine brain as a replacement for plastinated or formalin-fixed brains. The models investigated were built based on a micro-MRI of a single canine brain and have numerous practical advantages, such as durability, lower cost over time, and reduction of animal use. The effectiveness of the models was assessed by comparing performance among students who were instructed using either plastinated brains or 3D AM models. This study used propensity score matching to generate similar pairs of students. Pairings were based on gender and initial anatomy performance across two consecutive classes of first-year veterinary students. Students' performance on a practical neuroanatomy exam was compared, and no significant differences were found in scores based on the type of material (3D AM models or plastinated specimens) used for instruction. Students in both groups were equally able to identify neuroanatomical structures on cadaveric material, as well as respond to questions involving application of neuroanatomy knowledge. Therefore, we postulate that 3D AM canine brain models are an acceptable alternative to plastinated specimens in teaching veterinary neuroanatomy.

Cell trafficking through the choroid plexus

The choroid plexus is a multifunctional organ that sits at the interface between the blood and cerebrospinal fluid (CSF). It serves as a gateway for immune cell trafficking into the CSF and is in an excellent position to provide continuous immune surveillance by CD4 (+) T cells, macrophages and dendritic cells and to regulate immune cell trafficking in response to disease and trauma. However, little is known about the mechanisms that control trafficking through this structure. Three cell types within the choroid plexus, in particular, may play prominent roles in controlling the development of immune responses within the nervous system: the epithelial cells, which form the blood-CSF barrier, and resident macrophages and dendritic cells in the stromal matrix. Adhesion molecule and chemokine expression by the epithelial cells allows substantial control over the selection of cells that transmigrate. Macrophages and dendritic cells can present antigen within the choroid plexus and/or transmigrate into the cerebral ventricles to serve a variety of possible immune functions. Studies to better understand the diverse functions of these cells are likely to reveal new insights that foster the development of novel pharmacological and macrophage-based interventions for the control of CNS immune responses.

The neuropathogenesis of feline immunodeficiency virus infection: barriers to overcome

Feline immunodeficiency virus (FIV), like human immunodeficiency virus (HIV)-1, is a neurotropic lentivirus, and both natural and experimental infections are associated with neuropathology. FIV enters the brain early following experimental infection, most likely via the blood-brain and blood-cerebrospinal fluid barriers. The exact mechanism of entry, and the factors that influence this entry, are not fully understood. As FIV is a recognised model of HIV-1 infection, understanding such mechanisms is important, particularly as HIV enters the brain early in infection. Furthermore, the development of strategies to combat this central nervous system (CNS) infection requires an understanding of the interactions between the virus and the CNS. In this review the results of both in vitro and in vivo FIV studies are assessed in an attempt to elucidate the mechanisms of viral entry into the brain.

Ethanol suppression of peripheral blood mononuclear cell trafficking across brain endothelial cells in immunodeficiency virus infection

Earlier studies suggested that the combination of alcohol use and immunodeficiency virus infection resulted in more severe neurologic disease than either condition individually. These deleterious interactions could be due to increased immune cell and virus trafficking or may result from interactions between ethanol and human immunodeficiency virus (HIV)-associated toxicity within the brain. To determine the extent to which increased trafficking played a role, we examined the effect of ethanol on the migration of different peripheral blood mononuclear cell (PBMCs) subsets across a brain endothelial cell monolayer. We utilized combinations of feline brain endothelial cells with astrocytes, and/or microglia with either acute exposure to 0.08 g/dL ethanol, a combination of ethanol and feline immunodeficiency virus (FIV), or FIV alone. Adherence of PBMCs to endothelium was increased in all combinations of cells with the addition of ethanol. Despite increased PBMC adhesion with ethanol treatment, transmigration of B cells, monocytes, CD4 T cells and CD8 T cells was not increased and was actually decreased in the presence of astrocytes. Expression of three common adhesion molecules, intercellular adhesion molecule-1 (ICAM1), ICAM2, and vascular cell adhesion molecule, was unchanged or slightly decreased by ethanol. This indicated that although adherence is increased by ethanol it is not due to an increased expression of adhesion molecules. RANTES, MIP1α, MIP1β, and MCP-1 mRNA expression was also studied in brain endothelial cells, astrocytes and microglia by reverse transcriptase-polymerase chain reaction. Ethanol treatment of astrocytes resulted in modest changes of message while FIV caused 7–92-fold increases. The combination of ethanol and FIV reversed the large increase in RANTES and MIP1α message in astrocytes but increased MIP1β and MCP to 20–38-fold over control cells. Thus, modest concentrations of alcohol do not directly influence immune cell trafficking at the endothelium but may exert more complex effects on chemokine expression from astrocytes when combined with FIV.

Clinical anatomy of the canine brain using magnetic resonance imaging

The purpose of this study was to produce an magnetic resonsnce (MR) image atlas of clinically relevant brain anatomy and to relate this neuroanatomy to clinical signs. The brain of a large mixed breed dog was imaged in transverse, sagittal, and dorsal planes using a 1.5 T MR unit and the following pulse sequences: Turbo (fast) spin echo (TSE) T2, T1, and T2- weighted spatial and chemical shift-encoded excitation sequence. Relevant neuroanatomic structures were identified using anatomic texts, sectioned cadaver heads, and previously published atlases. Major subdivisions of the brain were mapped and the neurologic signs of lesions in these divisions were described. TSE T2-weighted images were found to be the most useful for identifying clinically relevant neuroanatomy. Relating clinical signs to morphology as seen on MR will assist veterinarians to better understand clinically relevant neuroanatomy in MR images.

Cerebrospinal fluid is an efficient route for establishing brain infection with feline immunodeficiency virus and transfering infectious virus to the periphery

Like human immunodeficiency virus (HIV), feline immunodeficiency virus (FIV) invades and infects the central nervous system (CNS) soon after peripheral infection. The appearance of viral RNA is particularly prominent in the cerebrospinal fluid (CSF), suggesting an efficient route of virus transfer across the blood-CSF barrier. This raises the concern whether this route can establish a stable viral reservoir and also be a source of virus capable of reseeding peripheral systems. To examine this possibility, 200 mul of cell-free NCSU1 FIV or FIV-infected choroid plexus macrophages (ChP-Mac) was directly injected into the right lateral ventricle of the brain. Negative controls were sham inoculated with uninfected ChP-Mac or virus-free culture supernatant and positive controls were infected systemically by intraperitoneal (i.p.) injection. Intracerebroventricular (i.c.v.) inoculation with cell-free FIV resulted in high levels of plasma FIV RNA detected as early as 1 to 2 weeks post inoculation in all cats. In each case, the plasma viremia preceded the detection of CSF viral RNA. Compared to i.p. cats, i.c.v. cats had 32-fold higher CSF viral loads, 8-fold higher ratios of CSF to plasma viral load, and a 23-fold greater content of FIV proviral DNA in the brain. No FIV RNA was detected in plasma or CSF from the cats inoculated with FIV-infected ChP-Mac but an acute inflammatory response and a slight suppression of the CD4+:CD8+ ratio were observed. These results indicate that free FIV circulating in the CSF promotes infection of the CNS and provides a highly efficient pathway for the transfer of infectious virus to the periphery.

Compartmentalization and evolution of feline immunodeficiency virus between the central nervous system and periphery following intracerebroventricular or systemic inoculation

The emergence of distinct neuropathogenic strains resulting from the adaptation and the unique evolution of human immunodeficiency virus (HIV) in the brain may contribute to the development of HIV-induced neurological diseases. In this study, the authors tracked early changes in virus evolution and compartmentalization between peripheral tissues and the central nervous system (CNS) after intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) inoculation of animals with cell-free feline immunodeficiency virus (FIV). Using the FIV-NCSU1 envelope V3-V4 heteroduplex tracking assay (HTA), the authors observed a rapid compartmentalization of envelope variants between the CNS and periphery. Animals receiving the i.c.v. inoculation showed two peaks of viral RNA in the cerebrospinal fluid (CSF) with very different HTA patterns. Compared to the initial viral peak in CSF, the second peak showed an increased compartmentalization from plasma, reduced viral diversity, and more divergence from the proviral DNA in peripheral blood mononuclear cells (PBMCs) and the choroid plexus. In contrast, changes in plasma over the same time period were small. Different animals harbored different FIV DNA genotypes with varied regional compartmentalization within the brain. These results demonstrated that the virus within the CNS experienced a relatively independent but variable evolution from the periphery. Initial penetration of virus into the CSF facilitated the development of brain-specific reservoirs and viral diversification within the CNS.

Astrocytes and microglia differentially regulate trafficking of lymphocyte subsets across brain endothelial cells

Feline brain endothelial cells (BECs), astrocytes, and microglia were combined in different configurations in a cell culture insert system to assess the effect of different cell types on the trafficking of peripheral blood mononuclear cell (PBMC) subsets in response to feline immunodeficiency virus (FIV). The addition of astrocytes to BECs significantly increased the adherence of PBMCs. This increase in adherence was suppressed by microglia, whereas microglia alone had no effect on PBMC adherence. FIV exposure of the glial cells did not alter PBMC adherence as compared to same configurations with untreated cells. All PBMC subsets showed some level of trafficking across the endothelial cell layer. The level of trafficking of monocytes and B cells was significantly increased if astrocytes were present. The presence of microglia with the astrocytes reduced transmigration across all PBMC subsets. FIV exposure of astrocytes significantly increased the percentage of CD8 T cell transmigration from 24% to 64% of the total CD4 and CD8 numbers. The presence of microglia significantly reversed the preferential trafficking of CD8 cells in the presence of astrocytes. The results suggested that interaction between the triad of endothelial cells, astrocytes, and microglia played an important, but varying, role in the trafficking of different PBMC subsets. In general, astrocytes had a positive effect on trafficking of PBMCs, while microglia had a suppressive effect. Effects of FIV on trafficking were largely restricted to increases seen in CD8 T cells and monocytes.

Cerebrospinal fluid centesis at the cerebellomedullary cistern of kittens

We needed an effective technique for obtaining cerebrospinal fluid (CSF) from young (2- to 18-week-old) kittens. Standard veterinary technique was not suitable, so we adapted a previously published technique for rats. We first established an effective isoflurane-only anesthetic protocol for young kittens. After inhalant anesthesia, the kittens were positioned on a supporting platform to gain flexion of the head and neck. A micromanipulator was used to hold and slowly advance the collection needle. At the time this report was written, we had collected a total of 33 samples from eight kittens without causing apparent neurologic deficits. Correct positioning of the animal and collection needle was critical for success. This procedure enabled the collection of approximately 0.5 ml CSF from kittens younger than 12 weeks and larger volumes from older kittens.

Choroid plexus macrophages proliferate and release toxic factors in response to feline immunodeficiency virus

Recent observations have suggested that lentiviruses stimulate the proliferation and activation of microglia. A similar effect within the dense macrophage population of the choroid plexus could have significant implications for trafficking of virus and inflammatory cells into the brain. To explore this possibility, we cultured fetal feline macrophages and examined their response to feline immunodeficiency virus (FIV) or the T-cell-derived protein, recombinant human CD40-ligand trimer (rhuCD40-L). The rhCD40-L was the most potent stimulus for macrophage proliferation, often inducing a dramatic increase in macrophage density. Exposure to FIV resulted in a small increase in the number of macrophages and macrophage nuclei labeled with bromodeoxyuridine. The increase in macrophage density after FIV infection also correlated with an increase in neurotoxic activity of the macrophage-conditioned medium. Starting at 16-18 weeks postinfection, well after the peak of viremia, a similar toxic activity was detected in cerebrospinal fluid (CSF) from FIV-infected cats. Toxicity in the CSF increased over time and was paralleled by strong CD18 staining of macrophages/microglia in the choroid plexus and adjacent parenchyma. These results suggest that lentiviral infection of the choroid plexus can induce a toxic inflammatory response that is fueled by local macrophage proliferation. Together with the observation of increasing toxic activity in the CSF and increased CD18 staining in vivo, these observations suggest that choroid plexus macrophages may contribute to an inflammatory cascade in the brain that progresses independently of systemic and CSF viral load.

Inverse relationship between the expression of the human papillomavirus type 16 transcription factor E2 and virus DNA copy number during the progression of cervical intraepithelial neoplasia

The human papillomavirus type 16 (HPV-16) status of 43 cervical biopsies, which had been characterized histologically as normal, various grades of cervical intraepithelial neoplasia (CIN) and invasive squamous cell carcinoma, was examined by using (i) a novel antibody against the HPV-16 E2 protein, (ii) sensitive HPV-16 DNA in situ hybridization and (iii) microdissection/PCR for the E2 ORF. The data indicate that E2 protein expression is highest in koilocytes in lower-grade CIN (I), but decreases with increasing grade, whereas the detection of HPV DNA is delayed until CIN I/II, rising to the highest levels in carcinoma cells. Co-localization of E2 with HPV-16 DNA-positive cells was most commonly observed in koilocytes in CIN II lesions. PCR analyses of microdissected epithelium from the same or serial sections indicated that E2 ORFs were retained in an intact form in a number of higher-grade CIN lesions and invasive carcinomas.

T cells overexpressing interferon-gamma and interleukin-10 are found in both the thymus and secondary lymphoid tissues of feline immunodeficiency virus-infected cats

Similar to human immunodeficiency virus type 1, feline immunodeficiency virus (FIV) replicates in the thymus of infected animals, causing marked alteration in thymic lymphocyte subpopulations. The immune phenotype and cytokine patterns in the thymus and secondary lymphoid tissues of FIV-infected cats were investigated. FIV infection caused an acute-stage transient reduction in CD4CD8 double-positive thymocytes, a marked increase in CD8 single-positive thymocytes, and formation of thymic B cell lymphoid follicles. Interferon (IFN)-gamma and interleukin (IL)-10 mRNA were up-regulated in both the thymus and lymph nodes of FIV-infected cats. Analysis of purified CD4 and CD8 cells revealed that CD4 cells produced most of the IL-10, whereas IFN-gamma was produced by both subsets. Quantitative-competitive reverse-transcription polymerase chain reaction analysis revealed that thymocytes, especially CD4CD8 thymocytes, had much greater levels of gag mRNA than did lymph node T cells. Thus, overexpression of IFN-gamma and IL-10 is a feature of the thymus and secondary lymphoid tissues of FIV-infected cats.

Shedding of feline immunodeficiency virus in semen of domestic cats during acute infection

OBJECTIVE

To examine shedding of cell-free and cell-associated feline immunodeficiency virus (FIV) in semen of domestic cats during acute infection.

ANIMALS

7 specific-pathogen-free sexually intact male cats.

PROCEDURE

6 cats were inoculated IV with 5 x 10(6) 50% tissue culture infective doses of FIV-NCSU1, and 1 cat served as an uninfected (control) cat. Infection was confirmed in the 6 cats. Periodically for up to 16 weeks after inoculation, cats were anesthetized and ejaculates obtained by use of electroejaculation. Virus was isolated from filtered seminal plasma and washed seminal cells by co-cultivation with a feline CD4+ T-cell line. Seminal cell lysates were also examined for a 582-base pair segment of FIV gag provirus DNA, using a nested polymerase chain reaction amplification.

RESULTS

During the acute phase of FIV infection, virus was evident in semen of 5 inoculated cats. Five cats had virus-positive seminal plasma and 3 had virus-positive cellular constituents during the study. Virus was isolated from 8/22 (36%) seminal plasma samples and 2/17 (18%) seminal cell specimens. Provirus DNA was detected in 5/24 (21%) seminal cell lysates. Cell-free virus was isolated as early as 6 weeks after inoculation, whereas cell-associated virus was isolated as early as 12 weeks after inoculation. Provirus DNA was detected in seminal cells from one cat as early as 1 week after inoculation.

CONCLUSIONS AND CLINICAL RELEVANCE

Cell-free and cell-associated FIV are shed in semen of cats early during the course of infection. Samples obtained before seroconversion may contain virus. Virus shedding in ejaculates varies between and within cats during acute infection.

Modulation of doxorubicin concentration by cyclosporin A in brain and testicular barrier tissues expressing P-glycoprotein in rats

P-glycoprotein (Pgp) is an inducible transmembrane protein that functions as an ATP-dependent efflux pump. Pgp is normally expressed in two types of cells: specialized epithelial cells with secretory/excretory functions (e.g., proximal renal tubules) and specialized endothelial cells (e.g., the capillary endothelial cells of the blood-brain barrier). In normal tissues, Pgp could exert a cytoprotective effect by facilitating excretion of drugs. It follows that inhibition of Pgp would alter the pharmacokinetics of drugs, like doxorubicin, in cells that express Pgp. The purpose of this study was to determine whether or not inhibition of Pgp by cyclosporin A (CsA) facilitated the transport of certain drugs across the blood tissue barriers of the brain and testes (barriers tissues expressing Pgp). 120 retired male breeder CD Fisher rats were randomly assigned to groups of 4 rats each. They were given either CsA, CsA vehicle, or saline followed by doxorubicin (Dox), cisplatin (CDDP), Evan's blue (EB), sodium fluorescein (NaF), or horseradish peroxidase (HRP). There was a CsA dose dependent increase in the tissue concentration of doxorubicin in brain and testes, but platinum (Pt) concentrations, derived from CDDP, were unaffected. Unlike CDDP, Dox, can be effluxed by Pgp. These increases in Dox concentrations were not due to altered vascular permeability as a result of CsA treatment as determined by lack of EB. NaF, or HRP in brain parenchyma. Modulation of Pgp function may prove to be useful for improving chemotherapy efficacy for patients with malignancies affecting tissues with blood-tissue barriers.

Clinical presentation of experimentally induced rabies in horses

Twelve naive and nine test-vaccinated horses which developed clinical signs of rabies as a result of the required protocol of a vaccine trial were prospectively observed. Nineteen of the 21 cases were confirmed positive for rabies infection of the brain by fluorescent antibody test. The two horses with negative results had ganglioneuritis of the trigeminal ganglion or lymphocytic perivascular cuffing in the brain stem in addition to clinical signs. Average incubation period was 12.3 days and average morbidity was 5.5 days. Naive animals had significantly shorter incubation and morbidity periods (P < 0.05). Muzzle tremors were the most frequently observed (81%) and most common initial sign. Other common signs were pharyngeal spasm or pharyngeal paresis (71%), ataxia or paresis (71%), lethargy or somnolence (71%). The furious form was manifested in 43% of rabid horses and some of these furious animals initially manifested the dumb form. The paralytic form was not observed. Histopathology was characteristics for rabies. The results of this trial do not reflect on the efficacy of commercially licensed equine rabies vaccines.

Use of a caudal auricular axial pattern flap in cats

A caudal auricular axial pattern flap was used in 3 cats to successfully reconstruct large cutaneous defects of the head that were a result of trauma or surgical excision of neoplasms. The technique was a convenient, practical, one-stage procedure for closure of the defects, and flaps up to 7.0 x 12.0 cm were developed. All flaps healed without complications. Anatomic landmarks and surgical guidelines for developing the flap were determined through anatomic dissections and angiographic studies of the cutaneous vasculature of the head and neck in feline cadavers. This report confirms findings of a previous study describing a platysma myocutaneous flap.

Clinical features of experimentally induced rabies in cattle and sheep

A total of 20 cattle and five sheep out of a larger group of animals that were experimentally challenged with virus as part of the required protocol for a vaccine trial developed clinical signs of rabies. All five sheep and 18 of the cattle tested positive for rabies in a direct fluorescent antibody (FA) test. The remaining two cattle had suspicious FA results. Prospective observations are reported in this study. In the diseased cattle, the average incubation period was 15.1 days and the average morbidity period was 3.7 days. Of those, the naive cattle had significantly shorter incubation and morbidity periods than the test-vaccinated cattle. Major clinical signs included excessive salivation (100%), behavioural change (100%), muzzle tremors (80%), vocalization (bellowing; 70%), aggression, hyperaesthesia and/or hyperexcitability (70%), and pharyngeal paresis/paralysis (60%). The furious form of rabies was seen in 70% of the cattle. In the diseased sheep, the average incubation period was 10.0 days and the average morbidity period was 3.25 days. Major clinical signs included muzzle and/or head tremors (80%), aggressiveness, hyperexcitability, and/or hyperaesthesia (80%), trismus (60%), salivation (60%), vocalization (60%) and recumbency (40%). The furious form of rabies manifested in 80% of the sheep. Current rabies vaccines on the market contain higher effective doses than that utilized for the test vaccine and the results of this study do not reflect in any way on commercially available ruminant rabies vaccines.

Persistent oropharyngeal membrane in a Hereford calf

Persistent oropharyngeal membrane was found in a 6-day-old Hereford calf. The calf was unable to nurse and had not passed feces since birth. Physical examination revealed a fold of tissue spanning the caudal oral cavity, and a barium study demonstrated that food remained within the oral cavity despite a swallowing reflex. A thickened epiglottis was demonstrated radiographically but was not confirmed on necropsy. Necropsy revealed a complete soft-tissue partition between oral cavity and oropharynx with a central blind-ended diverticulum. Only a few cases of persistent oropharyngeal membrane have been reported previously, all in humans. This is the first report of this defect in domestic animals. Possible similarities to the more common persistent anal membrane are discussed.

Symmetric bilateral brachymetacarpalia of a dog

Malformations of the canine manus are infrequently cited in the literature but include polydactylia and syndactylia. Here, a case of brachymetacarpalia affecting the second and fifth metacarpal bones of both forelimbs of a mixed-breed dog is described. The initial impression of shortened digits was disproved by statistical comparison with normal skeletons, but the presence of shortened metacarpal bones was demonstrated. Other malformations of the manus and appropriate terminology are briefly discussed.

Cerebrospinal fluid collection in rats: modification of a previous technique

Modification of a previously published technique for cerebrospinal fluid collection in rats is described. This technique uses general anesthesia, a supporting platform to flex the head-neck junction, a surgical approach to the dorsal atlanto-occipital region, and a micromanipulator to hold and control the approach of the collection needle. Critical steps for success of the procedure are correct positioning, avoiding premature incision of the subarachnoid space, and alignment of the collection needle with the midline and longitudinal axis of the head. The authors had a 95% success rate in obtaining > 0.1 ml of cerebrospinal fluid, using this technique.

Histochemical identification of the striated muscle of the canine esophagus

Histochemistry on the cervical, thoracic, and abdominal esophageal muscle of immature, young, and adult normal dogs revealed type IIA striated musculature in contrast to some other species. No other types or subtypes were observed. This suggests that esophageal muscle type is established at birth and does not vary or that any variation has been completed by 4 weeks-of-age unlike some canine limb musculature.

A possible feline model for human blepharospasm

'Benign essential blepharospasm' is a human eyelid disorder of unknown aetiology characterized by involuntary, bilateral, and disabling spasmodic contracture of the orbicularis oculi muscle. Treatments are frequently disappointing. Here we report what might be a first step toward developing an animal model for exploring mechanisms of the disorder and potential treatments. We surgically implanted stimulating electrodes into brain areas known to supply input to the lateral division of the facial nerve nucleus to induce blinking by electrical stimulation. Single-pulse stimuli at or near the facial, parabrachial, red, and interstitial nuclei produced consistent stimulus-induced eyelid contractions. Responses were ipsilateral to stimulation, except for the interstitial nucleus where contralateral responses occurred. Little or no other movements of the face, head, or body occurred at eye-blink threshold voltages. When these sites were stimulated with pulse trains, eyelid closures followed stimulus frequency and tended to fuse into constant closure. Thresholds at each stimulus site remained constant during three days of testing. Drug treatments produced no consistent effect on eye-blink threshold from any stimulation site, even when general behaviour was affected. We conclude that these input pathways to the facial nucleus may contribute to blepharospasm and that future neurochemical and electrophysiological study of these pathways may produce a suitable animal model for understanding this disorder.

Innervation of the feline eyelids

The innervation of the eyelids is incompletely understood. This is a particular problem for those who wish to develop animal models of eyelid dysfunction in humans. Blepharospasm, for example, is a disease of uncontrolled eyelid spasm that is difficult to manage clinically because the aetiology is not understood. The anatomical literature on eyelid innervation is sparse and even conflicting. We attempted to study eyelid innervation, both sensory and motor, with injection of horseradish peroxidase (HRP) into the superior eyelid, inferior eyelid, and bulbar conjunctiva. We used 13 anesthetized weanling cats. Shape and structure of the facial nucleus varied along its rostrocaudal extent, but there was a clear demarcation of lateral and medial division. HRP-filled facial nucleus cells were ipsilateral to the injection site, and label appeared throughout the rostrocaudal length. All injection sites, including bulbar conjunctiva, labelled facial nucleus neurons located with overlapping distribution, predominantly in the dorsal part of the lateral division. Likewise, heavy labelling occurred throughout the entire ipsilateral cranial cervical ganglion and the trigeminal ganglion in all kittens. Injection of upper or lower eyelids caused some labelling in the second through the fourth cervical spinal ganglia.

Horseradish peroxidase study of the location of extrinsic efferent and afferent neurons innervating the colon of dogs

The abdominal portion of the colon of 13 clinically normal dogs was divided into 5 regions (ascending, transverse, left colic flexure, proximal descending, and distal descending), and each region was injected with 30 mg of horseradish peroxidase (HRP). The injected colonic region, brain stem, L7-Cd1 portion of the spinal cord, sympathetic trunk ganglia, celiacomesenteric ganglia, caudal mesenteric ganglion, pelvic plexi, distal vagal (nodose) ganglia, and L1-Cd1 spinal ganglia were obtained at post-injection hour 48, sectioned, and processed by use of the tetramethylbenzidine method. The entire length of the colon was found to be under extrinsic influence of the parasympathetic nucleus of cranial nerve X (PX), with the largest average number of labeled cells resulting from injection of the ascending colon. It was also indicated that the entire colon is under extrinsic influence of the sacral portion of the spinal cord because the pelvic ganglia (second-order neurons) of the pelvic plexi contained labeled cells for all colonic regions. The largest average number of labeled cells in pelvic ganglia was seen after injection of the distal portion of the descending colon. Only after injection of the distal portion of the descending colon were labeled cells found in the S1-S3 portion of the spinal cord. Labeled cells in the PX, spinal cord, and pelvic ganglia were found bilaterally. Although the entire abdominal portion of the colon appears to be influenced by cranial and sacral parasympathetic preganglionic (via pelvic ganglia) neurons, the relative importance of the 2 areas seems to be reversed between the ascending colon and distal portion of the descending colon.(ABSTRACT TRUNCATED AT 250 WORDS)

Absence of an osseous patella and other observations in Macropodidae stifle

The patella is a large sesamoid bone that typically develops in the tendon of insertion of the large extensor muscles of the stifle joint. Although present in almost all species of mammals and birds, it has been found to be absent in the red kangaroo and two wallaby species (family Macropodidae). In its place is a fibrocartilage pad, located in the tendon of the quadriceps femoris muscle. This structure is visible grossly, is palpable, and has the form normally expected of a bony patella. In addition, the femoral trochlea is shallow and asymmetric, and the lateral gastrocnemius sesamoid is unusually prominent. These and other related modifications in the area of the Macropodidae stifle are presented.

A simplified method of casting the macroscopic airways of lungs

A technique for preparing casts of the macroscopic airways of mammalian lungs, which is both simplified and inexpensive in comparison with previous techniques, is described. The models are accurate, durable and flexible, and clearly demonstrate the orientation and branching pattern of the bronchial tree. The nature of the procedure also extends the availability of casts to laboratories or individuals with limited instrumentation and/or funding. Preliminary results using this technique to inject the lungs and certain air sacs of birds are also discussed.

The location of extrinsic efferent and afferent nerve cell bodies of the normal canine stomach

The location of the extrinsic efferent and afferent nerve cell bodies to the mucosa, submucosa, and tunica muscularis of the cardiac, gastric, and pyloric gland regions of the ventral stomach and to the mucosa-submucosa alone of these 3 glandular gastric regions was determined using the horseradish peroxidase technique. All animals of the study demonstrated labeling bilaterally in the rostrocaudal extent of the dorsal motor nucleus of the vagus nerve (DMV) although mucosa-submucosa injections resulted in fewer labeled cells in the DMV. There was no evidence of viscerotopic organization within the DMV for the different gastric regions. However, the left nucleus generally contained a greater number of labeled cells than the right nucleus. Injection of the mucosa, submucosa, and tunica muscularis of the cardiac gland region also resulted in labeling in the nucleus ambiguus in 4 of 5 animals. The vast majority of labeled postganglionic sympathetic neurons were found in the celiacomesenteric ganglion. Labeled cells were also located variously in the stellate ganglion, middle cervical ganglion, and sympathetic trunk ganglia for the different groups. There was no discernible pattern of localization of labeled cells within a sympathetic ganglion. For the stomach, afferent labeled cells were located in the range of the first thoracic to fourth lumbar spinal ganglia and the nodose ganglia, bilaterally. As with sympathetic neurons, there was no discernible pattern of localization of labeled cells within a sensory ganglion.

Percutaneous transtracheal ventilation and morphometric measurements of cervical structures in swine

Fifteen swine cadavers were examined to determine a quick, reliable means of locating the level of the cricothyroid ligament from consistently palpable structures in the head and neck area. From calculations of measurements made on these cadavers, it was discovered that when a 21-43 kg pig was placed in a standard position, the measured length (L) from the angle of the mandible to the manubrium sterni multiplied by a factor of 0.48 equals the parameter Z [L (0.48) = Z]. Z was measured, beginning at the manubrium sterni, along the ventral midline. The endpoint of Z was at the level of the cricothyroid ligament. A catheter inserted at this point through the ligament into the airway provides a means of transtracheal ventilation. This method of ventilation can be used in emergencies to avoid a tracheostomy or as an alternative to endotracheal ventilation. This method was applied successfully to four anesthetized pigs as determined by a series of arterial blood gas samples.

The origins of innervation of the canine caudal pharyngeal muscles: an HRP study

In deglutition, movements of the tongue and oropharynx direct a bolus to the laryngopharynx. The major muscles of this region, which includes the 'cricopharyngeal sphincter', must undergo sequential relaxation and contraction for correct swallowing action. The innervation of the caudal pharyngeal muscles involved in this action in the dog have not been determined previously by sensitive neuroanatomical techniques. In this study, the location of efferent and afferent neurons innervating the left cricopharyngeus, thyropharyngeus and hyopharyngeus muscles was determined by horseradish peroxidase (HRP) histochemistry in 7 puppies. Labeled cells were found ipsilaterally in the supraspinal nucleus, nucleus ambiguus (including nucleus retrofacialis) and nucleus intercalatus of all animals, in the parasympathetic nucleus of X (dorsal vagal efferent nucleus) of 6 animals, and in the hypoglossal nucleus of 4 animals. Small numbers of HRP-labeled cells were found contralaterally in the supraspinal nucleus of all animals, and in the rostral nucleus ambiguus, in the nucleus intercalatus and the parasympathetic nucleus of X of fewer animals. This defines a more extensive source of efferent neurons for these muscles than had been reported for the cat. Labeled postganglionic sympathetic neurons were found bilaterally in the cranial (superior) cervical, middle cervical and cervicothoracic (stellate) ganglia. Labeled afferent neurons were seen bilaterally in the proximal vagal (jugular) and distal vagal (nodose) ganglia and in the C1-C4 spinal ganglia. The location of sympathetic and sensory nerve cell bodies of the muscles of the laryngopharynx has not been previously reported.

The origins of innervation of the esophagus of the dog

This study defined the origins of extrinsic efferent and afferent innervation of the normal canine esophagus. When all the layers of the wall of the 3 esophageal regions (cervical, thoracic and abdominal) were injected with horseradish peroxidase (HRP), labeled nerve cells were found in the nucleus ambiguus (NA) and parasympathetic nucleus of X (PX) of the brainstem. Most labeled cells in the NA were located in the compact column (retrofacial nucleus) while labeled cells in the PX were located in separate rostral and caudal areas. There was no somatotopic organization in either the NA or PX. Labeled sympathetic postganglionic neurons were found in the cranial cervical, middle cervical, cervicothoracic, thoracic sympathetic trunk and celiacomesenteric ganglia. The HRP injection of the esophageal wall labeled sensory cell bodies in the glossopharyngeal, proximal and distal vagal, and C2-T6 spinal ganglia. There was no discernible pattern of distribution of labeled cells in the autonomic or sensory ganglia. When the HRP injections were confined to the mucosa-submucosa layers of the thoracic esophagus, a small number of labeled cells were identified in the NA; however, no labeled cells were found in the NA when injections were confined to the mucosa-submucosa of either the cervical or abdominal esophageal regions. With these confined injections, the labeled nerve cells appeared in the rostral part of the PX. Thus, it appeared that the internal tunics of the esophagus (i.e., the mucosa and submucosa) were innervated by neurons in the rostral PX while the muscular tunic was innervated by neurons in the caudal PX and the rostral NA. After mucosa-submucosa injections, labeled sympathetic neurons appeared in the same ganglia that were identified after whole wall injections and these had a similar random distribution. These injections also labeled neurons in the glossopharyngeal, proximal vagal, and distal vagal ganglia, but unlike the whole wall injections there was no labeling in the spinal ganglia. This suggested that the labeled cells of the spinal ganglia seen after whole wall injections conveyed impulses from the tunica muscularis and serosa.