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Biomedical subjects

R J Higgins

Publications and source records attributed to R J Higgins.

At least 91 records · Page 5Linked to original sources
PubMed1987

Enzyme-linked immunosorbent assay for the detection of antibodies to bovine virus diarrhea virus in sera from border disease virus-infected sheep.

An enzyme-linked immunosorbent assay (ELISA) was established for the rapid detection of specific antibodies against the causative agent of border disease in ovine sera. Polyethylene-glycol concentrated, equilibrium density gradient purified bovine virus diarrhea virus was used as test antigen. The optimal amount of antigen was 0.5 microgram/well, and the optimal concentration of conjugate was at 1/4,000 dilution. A total of 20 ovine serum samples, which had been collected from animals with or without border disease, were compared by ELISA and serum neutralization test for the detection of border disease-specific antibodies. ELISA was shown to be equally specific but less time-consuming and easier to perform than serum neutralization test. A positive correlation (r = 0.60) between the two tests was found.

Animals↗
PubMed1987

Tropism of border disease virus for oligodendrocytes in ovine fetal brain cell cultures.

Primary dissociated ovine brain cell cultures prepared from 50- or 140-day-old fetuses were inoculated with border disease virus (BDV). The cells present in the cultures were identified, using immunofluorescence procedures and sera against various CNS cell-specific markers. These markers were glial fibrillary acidic protein, myelin basic protein, myelin-associated glycoprotein, neuron-specific enolase, neurofilament protein, and fibronectin. Double-labeling immunofluorescence techniques for visualization of BDV antigen and of the CNS cell markers were used to evaluate the pattern of individual cell susceptibility 48 hours after infection. In cultures from fetuses of both ages, about half of the infected cells were glial fibrillary acidic protein-positive astrocytes. Scattered myelin-associated glycoprotein-positive oligodendrocytes were positive for BDV antigen, but only in the infected cultures from the older fetuses. Fibronectin-positive cells were not infected with BDV. In infected and noninfected cultures, cells positive for neuron-specific enolase, myelin basic protein, or neurofilament protein were not seen. Therefore, the remaining infected cells in all the cultures were not identified by the cell-specific markers used. Results of these in vitro experiments indicate that BDV does not selectively infect oligodendrocytes, and that such a selective pattern of infection may not be the basis for the in vivo congenital hypomyelination in sheep with border disease.

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PubMed1986

Acquired scoliosis associated with hydromyelia and syringomyelia in two dogs.

Progressive scoliosis resulting from hydromyelia and syringomyelia was found in 2 dogs. In one dog, hydromyelia was associated with pachymeningeal fibrosis, with adhesions in the cervical portion of the spinal cord. In the other case, a cause was not established. Neither dog had congenital CNS malformations. The clinicopathologic findings in the 2 dogs are described, and the etiology and pathogenesis of hydromyelia and syringomyelia are discussed.

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PubMed1986

Computed tomographic characteristics of primary brain tumors in 50 dogs.

Fifty histologically identified primary brain tumors in the dog were analyzed by computed tomography to establish criteria for identifying tumor types by computed tomography characteristics. Meningiomas could be distinguished from tumors within the brain parenchyma because they usually were broad-based, peripherally located masses that were enhanced homogeneously with contrast material. Among parenchymal tumors, astrocytomas were not distinguished easily from oligodendrogliomas because both tumors had similar features of ring-like and nonuniform enhancement, and poorly defined tumor margins. Choroid plexus tumors were seen as well-defined, hyperdense masses that had marked, uniform contrast enhancement. Pituitary tumors were distinguished readily by their location, minimal peritumoral edema, uniform contrast enhancement, and well-defined margins. Distinguishing features of other less frequently seen tumors (ependymoma, primitive neuroectodermal tumor, glioma, and neoplastic reticulosis) were not identified.

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PubMed1986

Characteristics of cisternal cerebrospinal fluid associated with primary brain tumors in the dog: a retrospective study.

Results of cisternal CSF analyses of 77 dogs with primary brain tumors (1970 to 1984) were examined retrospectively. The types of primary brain tumors were astrocytomas, choroid plexus papillomas, ependymomas, meningiomas, and oligodendrogliomas. Fifty-three dogs had complete CSF analyses performed (total WBC count, total protein content, and pressure). Of these 53 CSF, 39.6% had a pattern of change consistent with current descriptions of CSF associated with brain neoplasia. Results of the remaining 60.4% of the 53 CSF were normal (9.4%) or had an atypical pattern of abnormality (50.9%). The CSF associated with meningiomas was unique in having CSF with a WBC count greater than 50 cells/microliter and a WBC differential count greater than 50% polymorphonuclear (PMN) cells. Within the meningioma group, a predominance of PMN cells in the CSF correlated with necrosis or PMN cell infiltration of the tumors. Additional correlations between specific CSF characteristics and histologic features of the tumors could not be made. Statistical analysis of the 77 CSF revealed that the mean CSF total WBC count of the oligodendroglioma group was significantly less than the mean WBC count of the choroid plexus papilloma group and the meningioma group. The mean CSF total protein contents of the astrocytoma group and the meningioma group were significantly less than the mean protein of the choroid plexus papilloma group. The mean CSF pressure of the tumor groups was not significantly different. For all 77 tumors, the most common abnormality was an increased total protein content (69.4%); the least common abnormality was an increased total WBC count (41.3%).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1986

Characteristics of cerebrospinal fluid associated with canine granulomatous meningoencephalomyelitis: a retrospective study.

Cerebrospinal fluid of 22 dogs with histologically confirmed granulomatous meningoencephalomyelitis was analyzed, retrospectively. Seventeen dogs had cisternal CSF analysis, 4 dogs had lumbar CSF analysis, and 1 dog had both. For cisternal CSF, the mean +/- SEM total WBC count was 800.8 +/- 300.9 cells/microliter. The WBC differential count was predominantly lymphoplasmacytic cells, but 13 of the 18 cisternal CSF had polymorphonuclear (PMN) cells, and the mean +/- SEM PMN cell percentage was 18.6 +/- 5.3%. The mean +/- SEM total protein content of cisternal CSF was 255.8 +/- 98 mg/dl. Of 5 cisternal CSF pressures measured, 4 were within the normal range. The mean +/- SEM total WBC count and total protein content of lumbar CSF were 533.4 +/- 256.5 cells/mu/microliter and 163.2 +/- 25 mg of protein/dl, respectively. As with cisternal CSF, the WBC differential count of lumbar CSF was predominantly lymphoplasmacytic cells. Of 5 lumbar CSF, 4 contained PMN cells, but the percentage was less than the PMN cell percentage of cisternal CSF. Although variable, the general pattern of CSF abnormality associated with granulomatous meningoencephalomyelitis was different from the CSF abnormalities commonly seen with viral, bacterial, or mycotic encephalitides.

Animals↗
PubMed1986

Normal brain iodine-125 radiation damage: effect of dose and irradiated volume in a canine model.

High-activity iodine-125 sources in plastic catheters were surgically placed in the cerebral white matter of healthy beagle dogs and later removed. Reference doses, calculated at a point 0.75 mm from the source, ranged from 10 to 40 Gy. Necrosis, vascular-related damage, and edema were quantified by computed tomography. Volumetric analyses were used to derive the relationship of dose and dose rate to necrosis and contrast enhancement. The extent of necrosis was related to irradiated volume; a minimum effective dose averaging 180-200 Gy was required to induce this type of damage. Contrast enhancement was less dependent on irradiated volume or total dose. The extent of radiation-induced edema was directly related to the volumes of necrosis plus contrast enhancement. Noninvasive serial studies in a well-characterized in vivo model can address specific clinically related questions on damage to normal tissue after interstitial irradiation.

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PubMed1985

Astrocytoma in a boar.

A 2-year-old Duroc boar was examined because of weakness, ataxia, and blindness. During hospitalization, fever spikes of about 41.6 C (107 F) were recorded every 24 hours. The tentative diagnosis was a space occupying mass in the diencephalon. The boar's condition deteriorated rapidly, so the boar was euthanatized and necropsied. On the basis of gross and histopathologic findings, as well as cell marker-specific-staining characteristics, astrocytoma was diagnosed.

Animals↗
PubMed1985

Spread and distribution of viral antigen in nervous canine distemper.

Canine distemper virus (CDV) antigen was demonstrated immunocytochemically in the central nervous system (CNS) of 19 dogs killed from 16 to 170 days after infection. In the earliest lesions, infection of glial cells preceded demyelination, and the degree of myelin destruction correlated with the amount of viral antigen in the tissue. It was concluded that initial demyelination in distemper is directly viral-induced, but the nature of the infected glial cells remains uncertain. Ependymal infection and spread of virus in the subependymal white matter was often seen, suggesting invasion of CDV into the CNS along the CSF pathways. Inflammation during the latter stages of the infection appeared to be associated with viral clearance from the CNS in most dogs. In two dogs with chronic progressive neurologic distemper, viral antigen was still present in the brain suggesting that viral persistence and associated immunologic reactions may contribute to further myelin damage. With the exception of one dog that survived for 6 months after infection, viral antigen was no longer detected in the dogs that had recovered.

Animals↗
PubMed1985

Radiation brain damage induced by interstitial 125I sources: a canine model evaluated by quantitative computed tomography.

The canine brain is a good model of the human brain for studying radiation damage after megavoltage x-irradiation for brain tumors. We have further developed this model to study radiation damage induced by high activity interstitial 125I sources. Removable 125I sources were implanted in normal canine brains, and doses of 1,000 to 10,000 rads were delivered to a reference point at a 10-mm radius from the source; dose rates were 35 to 40 rads/hour at the reference point. Serial quantitative analysis of tissue damage (tissue density and contrast enhancement) was done using computed tomographic scanning up to 6 months after implantation and was compared to histopathological findings after the animals were killed. At doses greater than 19,000 rads (i.e., inside the reference point), frank coagulation necrosis was observed. Pronounced vessel-related changes, manifest as areas of contrast enhancement, corresponded to tissues receiving a minimum of 6,000 rads and a maximum of 19,000 rads. These results indicate that this model can be used in serial noninvasive studies to quantify the development of damage induced by interstitial irradiation and to provide dose-response information in individual animals.

Animals↗
PubMed1985

Comparison of total white blood cell count and total protein content of lumbar and cisternal cerebrospinal fluid of healthy dogs.

Lumbar and cisternal CSF from 31 healthy dogs were analyzed and compared statistically. The mean total protein of the lumbar CSF samples was 28.68 mg/dl; the mean total protein of cisternal CSF was 13.97 mg/dl. The mean total WBC count of lumbar CSF was 0.55 cells/microliter; the mean WBC count of cisternal CSF was 1.45 cells/microliter. Statistical analysis indicated that the protein and WBC differences between the 2 types of CSF were significant (P = less than 0.001 and P = less than 0.01, respectively).

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PubMed1984

Protozoal myeloencephalitis in horses in California.

Three cases of equine protozoal myeloencephalitis were diagnosed over a 12-month period in horses that had never left the state of California. These cases suggest that the disease is enzootic in California.

Animals↗
PubMed1983

Fat cow syndrome in a British dairy herd.

The fat cow syndrome developed over a two year period in a 100 cow dairy herd following overfeeding in late lactation and the dry period. It was characterised clinically by a high incidence of parturient paresis and chronic unresponsive ketosis in early lactation. The reproductive performance of the herd was poor throughout this period, with extended calving indices confirming a suggested link between fatty liver and infertility.

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