Search PubMed⌕ Search

Biomedical subjects

C Richardson

Publications and source records attributed to C Richardson.

At least 163 records · Page 9Linked to original sources
PubMed1986

Efficacy of porcine parvovirus vaccines.

Three inactivated porcine parvovirus vaccines were tested for efficacy in 66 susceptible gilts. The gilts were challenged with virulent virus on the 40th day of gestation. All the vaccines provided excellent protection against fetal mortality despite insignificant serological responses to one of them. Good protection was obtained with two of the vaccines even when the dose was substantially reduced. Unvaccinated controls had very few viable fetuses.

Animals↗
PubMed1986

Experimental infection of pregnant ewes with Listeria monocytogenes.

Eight 18-month-old ewes were infected orally with Listeria monocytogenes between 77 and 91 days of pregnancy. Only one ewe aborted, 10 days after the first infecting dose, at 94 days of gestation; L monocytogenes was isolated from several sites in both its aborted fetuses. Two days after the first infecting dose all the ewes exhibited mild illness and pyrexia lasting for two to three days but the ewe which aborted was seriously ill until nine to 10 days after aborting. Agglutination tests carried out on 2-mercaptoethanol reduced sera revealed a strong immunological response in all the infected ewes but in the ewe which aborted this response was delayed. Four uninfected ewes which were kept as controls remained healthy throughout the experiment and showed no evidence of 2-mercaptoethanol resistant antibodies to L monocytogenes. Growth retardation lines, occurring at the time of and after experimental infection, were found in the bones of 14 of 17 newborn lambs in both the infected and control groups; in the aborted lambs these lines occurred before the infection.

Abortion, Veterinary↗
PubMed1986

Characterization of reticulofibroblastoid colonies (CFU-RF) derived from bone marrow and long-term marrow culture monolayers.

The maintenance of hemopoietic precursors in long-term liquid bone marrow cultures (LTBMC) is associated with the presence of an adherent stromal layer composed of heterogeneous cell populations. We have used a culture assay to promote the growth of one of its cellular components and characterize its properties. Freshly obtained bone marrow cells and cells derived from the adherent layer of LTBMC were grown in methylcellulose-clotted plasma in the presence of phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM), hydrocortisone (HC), and citrated normal human plasma. Both sources contained cells (CFU-RF) that gave rise to colonies of cells with a reticulofibroblastoid appearance. In the presence of HC, most colonies contained lipid-laden cells. Colonies could be further propagated as adherent layers when transferred into liquid cultures. These cells produced laminin, fibronectin, and collagen types I, III, IV, and V. They were negative for Von Willebrand factor VIII. The ability to synthesize laminin and collagen type IV distinguished these cells from a population of previously described bone marrow fibroblasts (CFU-F). The relationship of CFU-RF to hemopoietic precursors was investigated using patients with chronic myeloid leukemia and bone marrow transplant recipients. Cells within CFU-RF-derived colonies were uniformly negative for the Philadelphia chromosome, thus making it unlikely that they belonged to the malignant hemopoietic clone. CFU-RF-derived colonies in bone marrow transplant recipients were found to be exclusively of host origin. Both observations support the view that CFU-RF is not part of the repertoire of hemopoietic stem cells.

Antigens↗
PubMed1986

The nucleotide sequence of the mRNA encoding the fusion protein of measles virus (Edmonston strain): a comparison of fusion proteins from several different paramyxoviruses.

Membrane fusion is the primary cytopathic effect observed in cells infected with measles virus. The viral protein responsible for this process has previously been defined as the fusion (F) protein. Fusion is activated by the proteolytic cleavage of a precursor molecule (F0) to yield two disulfide-linked polypeptides (F1 and F2). In this paper the mRNA for the membrane fusion protein has been cloned and the resulting cDNAs were sequenced. A mRNA composed of 2377 nucleotides was found to contain one open reading frame which could potentially code for a protein of 550 amino acids. This corresponding gene product was identified as the fusion protein through use of antibodies directed against a synthetic peptide which was constructed from the deduced amino acid sequence. A long and rather G-C rich 5' terminus was found on the mRNA and this noncoding region may play some role in regulation of protein synthesis at the translational level. Protein sequence data derived from the cDNA clones revealed a highly conserved F1 amino terminus which is characteristic of most paramyxoviruses. Very little amino acid homology (except for the conservation of the F1 terminus and 9 cysteines) was evident when the sequence was compared to other paramyxovirus fusion proteins. However an overall hydrophobic nature was characteristic of all the F proteins and hydrophobicity plots for the fusion proteins of 4 different paramyxoviruses were very similar. Computer analysis was also employed to analyze the secondary structure of the measles virus F protein. Large stretches of alpha helix were characteristic of the regions which purportedly interact with membranes. The functional domains of the F protein and their similarity to those of the influenza hemagglutinin protein are discussed in this communication. We concluded that the distribution of hydrophobic regions capable of spanning biological membranes determines the fusogenic nature of the F protein.

Amino Acid Sequence↗
PubMed1986

Ribosomal initiation at alternate AUGs on the Sendai virus P/C mRNA.

Peptide sera specific for the C, C/C', and P proteins of Sendai virus have been used to confirm that the viral nonstructural proteins originate from internal AUG codons and are translated in a different reading frame from that of the P protein. The C protein undergoes aberrant migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and is expressed at higher levels in infected cells than are the P and C' proteins.

Animals↗
PubMed1986

Changes in muscle activity during fast, alternating flexion-extension movements of the knee.

The effects of high frequency alternating knee flexion-extension on muscle activity of the quadriceps and hamstring muscle groups has been investigated. Standard loads were used for each subject. The muscle activity in vastus medialis, vastus lateralis, rectus femoris and the lateral hamstrings were recorded by electromyography during increasing velocities. Rectus femoris and hamstrings were found to increase their activities significantly with increasing speed while vastus medialis and vastus lateralis showed no such change. The individual thigh muscles thus differ in function in relation to the velocity of movement.

Adult↗
PubMed1985

Skeletal abnormality of sheep: clinical radiological and pathological account of occurrence of dwarf lambs.

Details are given of the clinical, radiological and pathological appearance of dwarf lambs. Twenty-seven of 110 lambs born were affected, occurring as singletons, twins or one of a pair of twins. All affected lambs were dead within a few minutes of birth. They were short and plump with a domed head and shortened nose, short paddle-like limbs, a narrow thorax and swollen abdomen. The defect involved chondrocyte dysplasia, producing defective endochondral ossification and the presence of abnormal cartilage in the respiratory tract. No specific genetic or environmental cause was identified.

Animals↗
PubMed1985

Electromyographic and neuromuscular force patterns associated with unexpectedly loaded rapid limb movements.

A series of ballistic, unidirectional arm movements were studied to evaluate the electromyographic (EMG) and neuromuscular force patterns that occur when a limb is unexpectedly perturbed. Multiple training trials were continued with a control load spring attached to the apparatus until a pre-specified criterion for learning was attained. The limb was then unexpectedly loaded with one of four test load springs. Examination of the integrated EMG records revealed a coactivation pattern of neuromuscular activity during a major part of the movement. Analysis of applied force data supported the notion of sustained agonist activity. Reciprocal innervation and coactivation patterns were considered in terms of a common motor control system as proposed by the equilibrium point control hypothesis. Manifestation of coactivation rather than reciprocation in the present study was discussed in terms of the execution of unloaded/inertially loaded movements and variable loaded movements.

Biomechanical Phenomena↗
PubMed1985

Observations on transplacental infection with bluetongue virus in sheep.

Twenty-four ewes were inoculated with 1 of 2 strains of bluetongue virus type 4 at 40, 60, or 80 days of gestation. Two ewes aborted, 2 ewes died, and 1 was killed during the experiment, but their fetuses were recovered. At term, 2 mummified fetuses, 4 dead lambs, and 17 clinically healthy lambs were produced by 12 sheep, and the remaining 7 sheep were barren. Porencephaly and cerebellar dysgenesis were found in term lambs born to sheep inoculated at 40 and 60 days of gestation. Radiographic examination of 12 fetuses showed developmental ages far less than their chronologic age; 8 fetuses had skeletal growth-retardation lines, which were also observed in the dead lambs. A systemic lymphoreticular hyperplasia was observed in the dead lambs and in all lambs at 12 weeks of age; in 4 of the latter, granulomatous reactions were present in the liver and kidney. Lungs of the full-term lambs were reduced in weight and showed poor alveolar development and mononuclear cell infiltration, which persisted in the 12-week-old lambs. It was concluded that bluetongue virus is capable of causing not only gross abnormalities of the CNS, but also generalized growth retardation and fetal lymphoreticular hyperplasia.

Abortion, Veterinary↗
PubMed1984

Bovine virus diarrhoea-mucosal disease virus-induced fetopathy in cattle: Efficacy of prophylactic maternal pre-exposure.

Maternal immunity was produced in Jersey heifers by exposing them to bovine virus diarrhoea-mucosal disease virus before conception. In the following pregnancy this immunity protected the fetuses from transplacental infection arising from challenge of the dams at 100 days gestation with homologous virus. Unprotected Jersey heifers showed a high incidence of death and fetal intrauterine growth retardation associated with transplacental viral infection. Functional normality of the locomotor system was assessed retrospectively from ciné films of each calf after birth, and scored for each of an overlapping series of clinical signs. The progeny of non-immune dams scored significantly lower than calves from the vaccinated heifers.

Animals↗
PubMed1984

Maintenance of equilibrium point control during an unexpectedly loaded rapid limb movement.

Two experiments investigated whether the equilibrium point hypothesis or the mass-spring model of motor control subserves positioning accuracy during spring loaded, rapid, bi-articulated movement. For intact preparations, the equilibrium point hypothesis predicts response accuracy to be determined by a mixture of afferent and efferent information, whereas the mass-spring model predicts positioning to be under a direct control system. Subjects completed a series of load-resisted training trials to a spatial target. The magnitude of a sustained spring load was unexpectedly increased on selected trials. Results indicated positioning accuracy and applied force varied with increases in load, which suggests that the original efferent commands are modified by afferent information during the movement as predicted by the equilibrium point hypothesis.

Humans↗
PubMed1984

A pulmonary abnormality of newborn lambs.

Nineteen pregnant ewes deliberately infected orally with Campylobacter coli/jejuni at either 80 or 120 days gestation and accidentally subjected to a period of heat stress during the latter half of pregnancy produced clinically normal but growth-retarded lambs at term. A group of 7 pregnant ewes uninfected with Campylobacter but subjected to the same heat stress produced lambs clinically and morphologically similar to the lambs of the other 2 groups. Microscopically, the lungs from 11 lambs showed areas of increased cellular density which were interpreted as pulmonary collapse. The cause remains unknown, but the lesion could have its origins in some form of airway obstruction associated with intra-uterine infection and/or heat stress.

Animals↗
PubMed1984

Ontogeny of brain neurotensin in the rat: a radioimmunoassay study.

Concentrations of neurotensin-like immunoreactivity in several discrete brain areas were measured by radioimmunoassay in rats of different ages (2, 5, 10, 20, 30, and 60 days). Neurotensin-like immunoreactivity increased steadily from 2 to 30 days of age in the hypothalamus and then plateaued, while the preoptic area and amygdala concentrations peaked at 30 days of age. Brainstem neurotensin-like immunoreactivity concentrations increased from 2 to 10 days of age and decreased from 20 to 60 days of age. Several other regions showed no significant age-associated changes in neurotensin-like immunoreactivity.

Amino Acid Sequence↗
PubMed1983

Changes in nucleotide-binding proteins during oocyte maturation in Xenopus laevis.

Photoaffinity nucleotide analogs of ATP and GTP have been used to investigate the purine nucleotide-binding proteins of Xenopus laevis oocytes. These analogs label Xenopus oocyte supernatant proteins in a highly specific manner. The pattern of proteins labeled with these analogs was determined by polyacrylamide gel electrophoresis. A number of changes in this pattern were observed during the time course of progesterone-stimulated maturation in vitro. If one alters the dynamic balance of phosphatase and kinase activities with NaF, these changes are not observed. This photoaffinity approach also provides an assay for the purification of high-affinity nucleotide-binding proteins, including protein kinases, which may be important in the process of oocyte maturation.

Adenosine Triphosphate↗
PubMed1983

Lymphocyte markers in the bovine foetus.

The ontogeny of lymphocyte surface markers was studied in thymus, retropharyngeal lymph nodes, spleen, bone marrow, and liver of 48 bovine foetuses, 80-280 days of gestation. The markers examined were the spontaneous (E) rosette against sheep erythrocytes (SRBCs) in foetal calf serum (E/FCS), in medium supplemented with gelatin (E/CFG), and in medium supplemented with dextran (E/dextran), the erythrocyte-antibody (EA) rosette for immunoglobulin (Fc) receptors, the erythrocyte-antibody-complement (EAC) rosette for complement receptors, and the immunofluorescence test (IFT) for surface-membrane immunoglobulins (SmIg). E-rosette-forming cells (RFCs) occurred in the thymus in substantial numbers throughout the period studied, in spleen and lymph nodes only after 160 days, and in bone marrow and liver rarely. The dynamics of E rosettes formed in the three supplements suggested that each supplement might be supporting rosette formation by different populations of cells, albeit considerable overlap might be expected. Organ distribution and development of EA and EAC RFCs did not parallel the expected ontogeny of any class of lymphocytes. Cells carrying SmIg developed mainly in spleen and lymph nodes. Towards the end of gestation some cells in liver also had SmIg.

Animals↗
PubMed1983

Release of protein from normal and mutant tomato cell walls.

The nitrogen content of cell wall preparations from normal tomato (cv Ailsa Craig) fruit remained constant during ripening, whereas salt-soluble protein increased throughout this process. Tomato polygalacturonase released about twice as much protein from the preparations as salts did, with a maximum at the orange stage of development. Polygalacturonase-solubilized protein from the tomato mutant ;ripening inhibitor' (rin) was less, and that from the mutant ;Never ripe' (Nr) cell walls was more than that from normal wall preparations. Release of protein by fungal cellulase was limited, but was increased by the addition of polygalacturonase from the same source. Salt-solubilized protein contained a range of enzymic activities but these were distributed between fewer multimolecular forms than is the case for whole cell preparations. The results suggest that metabolically active protein, removable by strong salt solutions, cellulase, or polygalacturonase, remains attached to the cell walls of tomato fruit until late in ripening. The unusual amounts of protein attached to the cell walls of mutant fruit appear to be a reflection of the absence of some or all of the isoenzymes of polygalacturonase that are associated with normal ripening.

Journal Article↗
PubMed1982

Strategies of intervention with families of pediatric leukemia patients: a longitudinal perspective.

As part of a longitudinal research study, families of children with leukemia were provided with a psychosocial intervention program over a two-year period. This paper describes the approaches used at specific times during the illness: diagnosis and initial treatment, early outpatient treatment, later outpatient treatment, remission, relapse, and death. The goals of the intervention strategies were to facilitate: an understanding of the realities of the illness; management of emotional distress; and utilization of resources to care for the child, attend to other responsibilities, and support and communicate with one another.

Age Factors↗