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Biomedical subjects

W C Hall

Publications and source records attributed to W C Hall.

At least 73 records · Page 4Linked to original sources
PubMed1978

Identification of Rickettsia rickettsii in formalin-fixed, paraffin-embedded tissues by immunofluorescence.

With slight modification of a trypsin digestion technique, Rickettsia rickettsii were demonstrated specifically by immunofluorescence staining in Formalin-fixed, paraffin-embedded tissue sections from a human, rhesus monkey, and guinea pig with Rocky Mountain spotted fever and in infected membranes from a chicken embryo. Tissues were cut at 4 micron and, using geltain as a tissue adhesive, were hydrated in a routine manner. Sections were then digested in refrigerated 0.1% trypsin for 16 h, washed, and stained specifically for R. rickettsii by direct or indirect immunofluorescence. Rickettsial organisms were localized in affected vessels of the mammalian species and within the yolk sac epithelium of the chicken embryo. Specificity was confirmed by adsorbing antibody conjugates with R. rickettsii organisms. Trypsin digestion probably decreased tissue proteins which interfered with immunochemical attachment of antibody to the rickettsiae. The technique is valuable in that a diagnosis of Rocky Mountain spotted fever can be confirmed from Formalin-fixed tissues processed in a routine manner.

Animals↗
PubMed1977

The organization of the pulvinar in the grey squirrel (Sciurus carolinensis). I. Cytoarchitecture and connections.

The posterior neocortex in the grey squirrel, Sciurus carolinensis, includes an extensive region which receives projections from the pulvinar. Previous studies have demonstrated that this cortical region can be subdivided on the basis of differences in cytoarchitecture and electrophysiologically defined representations of the visual field. The main purpose of the present paper was to determine whether these cortical subdivisions could be related to corresponding subdivisions in the pulvinar. The methods used to trace connections included anterograde degeneration, anterograde axonal transport of tritiated amino acids and the retrograde axonal transport of horseradish peroxidase. The results indicate that the pulvinar in this species contains at least three main subdivisions which can be distinguished by their cytoarchitecture and their patterns of connections. A caudal subdivision contains large, evenly-spaced neurons and receives bilateral input from the superficial, retinal-recipient layers of the superior colliculus. This caudal subdivision has reciprocal interconnections with a cytoarchitectonically distinct area in the temporal cortex. A rostro-lateral subdivision contains smaller, more lightly stained neurons which tend to form clusters. This subdivision receives only ipsilateral tectal input and projects to occipital area 18. This subdivision does not receive input from areas 17, 18, and 19, or from the temporal cortex. Finally, a rostro-medial subdivision is cytoarchitectonically similar to the rostro-lateral subdivision but receives little, if any, input from the superior colliculus. This rostro-medial area does, however, receive corticofugal projections from occipital areas 17, 18, and 19, and projects to area 19. These patterns of connections suggest that each of these subdivisions has close associations with the visual system. The question of whether similar subdivision are present in the visual thalamus of other species is discussed.

Afferent Pathways↗
PubMed1977

The organization of the pulvinar in the grey squirrel (Sciurus carolinensis). II. Synaptic organization and comparisons with the dorsal lateral geniculate nucleus.

The purpose of these experiments was to compare the synaptic organization of the subdivisions of the pulvinar defined in the preceding paper (Robson and Hall, '77) with each other and with the organization present in the dorsal lateral geniculate nucleus. The electron microscope was used to analyze normal synaptic arrangements and degenerating axonal terminals resulting from lesions. The dorsal lateral geniculate nucleus in the grey squirrel contains synaptic clusters similar to those described previously for other species. These clusters are characterized by large optic tract terminals which form multiple contacts onto large dendritic processes and other processes containing flat or pleomorphic vesicles. The geniculate lamina adjacent to the optic tract receives projections from the superior colliculus as well are from the retina. The terminals of the superior colliculus axons are small and medium sized and lie outside of the synaptic clusters. The retinal terminals are in the clusters. In the pulvinar, the rostro-medial subdivision contains synaptic clusters which resemble those in the lateral geniculate nucleus. These clusters contain large axon terminals which make multiple contacts onto large dendrites. However, these terminals are not contributed by an ascending sensory pathway but by axons from striate cortex. The rostro-lateral and caudal subdivisions of the pulvinar also contain synaptic clusters, but these clusters consist of a segment of a large dendrite which is ensheathed by medium-sized terminals. Since only a few of these medium sized terminals in any one cluster degenerate after tectal lesions, and none degenerate after cortical lesions, it is suggested that the morphological arrangement of these clusters may permit the convergence of axons from several sources, some of which are unidentified, onto the same dendritic segment.

Animals↗
PubMed1977

Efferent projections of the main and the accessory olfactory bulb in the tree shrew (Tupaia glis).

The projections of the main and the accessory olfactory bulb in the tree shrew (Tupaia glis) have been analyzed with anterograde degeneration and autoradiographic methods for identifying axonal projections, and with the horseradish peroxidase method for identifying the distribution of neurons from which these projections originate. The cytoarchitectonic features of the paleocortical areas which receive projections from the main and the accessory olfactory bulb have also been described. The efferent projections of the accessory olfactory bulb are distributed to the bed nucleus of the accessory olfactory tract, the medial amygdaloid area, the posteromedial cortical amygdaloid area, and to the caudal portion of the bed nucleus of the stria terminalis. In contrast, the efferent projections of the main olfactory bulb are distributed to the anterior olfactory nucleus, the tenia tecta, the olfactory tubercle, the pyriform cortex, the anterior cortical amygdaloid area, the posterolateral cortical amygdaloid area, and to the lateral entorhinal cortex. These observations are consistent with the notion that the olfactory system can be divided into at least two major subsystems: one related to the vomeronasal organ and accessory olfactory bulb, and another related to the main olfactory organ and main olfactory bulb. The paleocortical areas receiving olfactory projections have three basic layers: a superficially positioned plexiform layer (layer I), a pyramidal cell layer (layer II), and a polymorphic cell layer (layer III). The projections of both the main and the accessory olfactory bulb terminate in the outer portion of the plexiform layer (sublamina Ia). Sublamina Ia contains the distal segments of dendrites which originate from a heterogeneous population of neurons located in layer II and, to a lesser extent, layer III. Although the efferent projections of the main and the accessory olfactory bulb are segregated, evidence for a more refined topographical organization within these projections was not obtained. However, the distribution of retrogradely labeled neurons in the main olfactory bulb, following injections of horseradish peroxidase into its various paleocortical targets, indicates that the olfactory projections to these areas may not all originate from the same population of cells.

Amygdala↗
PubMed1977

Use of a photodensitometric technique to quantify microscopic lung lesions in mice: Antiviral activity against swine influenza virus.

During studies of swine influenza virus (A/NJ/76) infection, a technique was devised to quantify the pulmonary lesions in infected mice treated at different time intervals with antiviral chemotherapeutic agents. The technique is based on the premise that as the severity of microscopic change increases, the optical density of lung sections also increases because of edema and increased cell numbers in infected lungs. Seven days after intranasal instillation of the virus, mice were killed and the lungs were perfused with 2% glutaraldehyde at constant pressure. Lungs were processed in a routine manner, sectioned at standard levels, and stained with hematoxylin and eosin. By using standard photomicrography equipment, multiple optical density measurements were made of lung sections in a carefully controlled systematic manner, and a mean optical density was determined for each lung. The optical density of lungs of mice treated before and after infection with amantadine, rimantadine, or ribavirin was significantly reduced compared with that of the lungs of infected, untreated controls. If treatment was delayed until 15 h after infection, amantadine and ribavirin were effective in reducing pulmonary optical density, but rimantadine was without effect. These findings correlated well with mean lung weight of each group; however, the sensitivity of the optical density technique was greater. Subjective scoring of microscopic lesions revealed differences only between infected and uninfected controls. The densitometric method offers promise as a reliable means of objectively quantifying the pulmonary response to a variety of infectious, toxic, and therapeutic agents.

Animals↗
PubMed1977

Reaction of squirrel monkeys to intratracheal inoculation with influenza/A/New Jersey/76 (swine) virus.

To determine whether a model could be established for laboratory investigations, nine squirrel monkeys were inoculated intratracheally with 10(7) median egg-infectious doses of influenza virus type A/New Jersey/8/76 (HSW1N1) (swine influenza virus). They responded with clinically detectable illness including fever, leukopenia, decreased food consumption, increased respiratory rate, occasional coughing, labored breathing, nasal discharge, and lethargy. Convalescence was well advanced by the day 10. All monkeys excreted virus for 7 to 8 days. A scoring procedure (illness score) has been developed for use in studies of vaccine and chemotherapeutic efficacy.

Animals↗
PubMed1976

Tumours of the prostate and penis.

Tumours of the male genital tract, excluding the testes, are relatively rare in the six major domestic animals. The most important tumours are prostate carcinoma and transmissible venereal tumour of the penis in dogs, fibropapilloma of the penis in bulls, squamous papilloma and squamous cell carcinoma in horses, and squamous papilloma in pigs. Four histological types of canine prostate carcinoma exist: alveolar papillary, acinar, organoid, and poorly differentiated. The biological behaviour of prostate carcinomas is similar to that in man, with frequent metastasis to the regional pelvic nodes, bones, and lungs. There appears to be no relationship between the common diffuse glandular hyperplasia and carcinoma in the prostate of dogs. A unique lesion of dogs is squamous metaplasia of the prostate related to estrogen-producing Sertoli cell tumours of the testis. Three different transmissible tumours of the penis occur in domestic animals. The canine venereal tumours can be transmitted only by intact tumour cells during licking and coital contact, whereas bovine fibropapillomas and porcine squamous papillomas can be transmitted by cell-free material. In cattle, the fibropapillomas are caused by the same virus that produces cutaneous papillomatosis. All three tumours are benign and usually regress spontaneously.

Animals↗
PubMed1975

The connections and laminar organization ofthe optic tectum in a reptile (lguana iguana).

The goals of this study were: (1) to describe the total pattern of projections from the optic tectum of Iguana iguana and Pseudemys scripta; and (2) to describe the contributions of particular lamina of the Iguana's optic tectum to this total pattern. Lesions were made in the optic tectum of the Iguana which damaged either all or only certain tectal laminae and, for comparison with the Iguana, lesions in the turtle's optic tectum were made which involved all laminae. The anterograde degeneration resulting from these lesions was stained with the Fink-Heimer ('67) method. The total pattern of projections from the optic tectum in the Iguana and the turtle is similar to that reported for representatives of other vertebrate classes. That is, the optic tectum gives rise to ipsilateral ascending projections to pretectal nuclei, to nucleus rotundus and to nucleus geniculatus lateralis pars ventralis of the diencephalon and, in addition, to a contralateral ascending pathway which courses via the supraoptic decussation to the contralateral diencephalon. Tectotectal connections and several descending pathways were also recognized in each species. The descending pathways include ipsilateral tectobulbar and tecto-isthmi pathways and a contralateral predorsal bundle. Lesions which damaged only certain tectal laminae in the Iguana revealed a laminar organization of the efferent projections. A lesion restricted to the superficial retinal-recipient layers, stratum griseum et album superficiale, resulted in degeneration in only nucleus isthmi pars magnocellularis and nucleus geniculatus lateralis pars ventralis. A lesion which involved both the retinal-recipient layers and stratum griseum centrale resulted in degeneration in only one additional structure, nucleus rotundus. A small lesion involving the deep periventricular layers as well as the superficial layers produced degeneration in the predorsal bundle and the ipsilateral tectobulbar tract as well as in the structures receiving input from the more superficial layers. These results are compared to the results of similar analyses of the superior colliculus in mammals.

Animals↗
PubMed1975

The pulvinar nucleus of Galago senegalensis.

The present study was undertaken to analyze the connections of the pulvinar nucleus in a prosimian. The experiments, which rely on the Fink-Heimer ('67) method for staining degenerating axons and their terminals, fall into two parts: first, the tracing of ascending tectal projections to the caudal thalamus and second, the tracing of projections from this thalamic target to the cortex. Large lesions of the superior colliculus resulted in dense degeneration in the caudal half of the inferior subdivision of the pulvinar complex. This pathway could be identified when the lesion was restricted to the superficial layers of the superior colliculus, signifying that it is a visual pathway. In general, the projections of the deep and superficial layers of the superior colliculus were distinct and in this respect Galago resembles Tupaia. The inferior pulvinar nucleus in turn projects to area MT, a conspicuous subdivision of the temporal cortex. The superior division of the pulvinar, in contrast to the inferior division, is not a major target of ascending projections from the superior colliculus and projects to the areas of the occipital and temporal lobe intercalated between areas MT and 17. When these results are compared with similar studies in nonprimates, notably studies of Tupaia, a striking difference in organization emerges. In Tupaia, and in distantly related mammals such as the squirrel, the target of the tecto-pulvinar system includes area 18 adjacent to area 17. This feature is important since the two parallel projection systems seem to be related to each other in terms of the way in which the zero vertical meridian is spatially represented. However, in Galago the subdivision of the pulvinar receiving projections arising from the superior colliculus does not project to area 18. Area 18 is indeed the target of pulvinar projections, but these projections arise from that portion of the pulvinar which is not a recipient of ascending tectal projections. It is not easy to see how this primate organization, if indeed the Galago is representative of primates, evolved from the organization reflected in Tupais.

Animals↗
PubMed1975

Subdivisions of the medial geniculate body in the tree shrew (Tupaia glis).

The medial geniculate body of the tree shrew has 3 major divisions which can be identified on the basis of cytoarchitecture. Each of these major divisions can be subdivided further. The present paper describes these divisions and compares them in terms of their patterns of afferent and efferent connections. In particular, anterograde degeneration and autoradiographic techniques are used to demonstrate that the dorsal and medial divisions receive projections from the deep layers of the superior colliculus and from the tegmentum. Results are also presented which indicate that the dorsal division projects to a non-primary cortical area adjacent to primary auditory cortex. Evidence is discussed which suggests that large sectors of what we have called the medial geniculate body constitute subdivisions of the auditory thalamus.

Animals↗