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Biomedical subjects

G C Smith

Publications and source records attributed to G C Smith.

At least 325 records · Page 18Linked to original sources
PubMed1978

Observation of togavirus-like particles in nonhuman primates.

Particles resembling togaviruses were observed by electron microscopy in the urinary bladder lamina propria of one capuchin monkey and in placental syncytiotrophoblasts of one baboon. Type C viruses were observed in the baboon placenta, but not in the tissues of the capuchin monkey.

Animals↗
PubMed1977

Oncornavirus: isolation from a squirrel monkey (Saimiri sciureus) lung culture.

An oncornavirus isolated from a squirrel monkey (Saimiri sciureus) lung culture has a density of 1.16 to 1.17 grams per milliliter, contains 70S RNA, and has an RNA-directed DNA polymerase that prefers Mg2+ over Mn2+ in an assay in which polyribocytidylate - oligodeoxyguanylate (12-18) is used as a synthetic template. Morphologically, the virus resembles Mason-Pfizer monkey virus but is antigenically distinct from this virus. The virus grows in cells of human, chimpanzee, rhesus monkey, canine, and mink origin, but not cells of squirrel monkey origin. On the basis of its properties, the newly isolated virus can be classified as a retravirus.

Animals↗
PubMed1977

Oncornavirus-like particles in squirrel monkey (Saimiri sciureus) placenta and placenta culture.

Oncornavirus-like particles similar in morphology to type D particles were observed in 1 of 2 squirrel monkey (Saimiri sciureus) placentas. Intracytoplasmic type A particles, immature virus particles, and mature viruses with eccentric or occasionally centric nucleoids were associated with placental syncytiotrophoblasts. A spike layer typical of type B viruses was not detected in viral envelopes. Onvornaviruses, identical to those previously isolated from squirrel monkey tissues and similar to Mason-Pfizer monkey virus, were seen in cultures derived from the virus-positive squirrel monkey placenta cocultivated with a mink lung culture. The major morphologic difference between the in vivo and the in vitro squirrel monkey virus was in the nucleoid position of mature virus particles.

Animals↗
PubMed1977

Rio Grande--a new phlebotomus fever group virus from south Texas.

Three strains of a new Phlebotomus fever group virus were isolated from pack rats (Neotoma micropus) collected in south Texas during 1973--1974; the name Rio Grande was proposed for this virus. The virus is pH 3.0 labile, sensitive to the action of sodium deoxycholate and heat (56 degrees C) labile. The results of a serosurvey indicated that pack rats are probably the principal vertebrate host for Rio Grande virus and that year-round transmission of the virus may occur. Because no isolations of this virus were made from hematophagous insects, the vector, if any, remains undetermined.

Animals↗
PubMed1976

Effects of monosodium glutamate administration in the neonatal period on the diabetic syndrome in KK mice.

Administration of monosodium glutamate (MSG) to KK mice during the neonatal period resulted in a syndrome of obesity, stunting and hypogonadism. In some animals the genetic predisposition to diabetes was unmasked with the development of marked hyperglycaemia and or hyperinsulinaemia. Food intake was not increased compared to controls. The elevated plasma glucose and insulin in fed MSG treated mice fell rapidly with food deprivation. Glucose disposal was comparable in MSG treated and control mice after IP glucose, but after oral glucose MSG treated mice showed impaired glucose tolerance. Insulin secretion was defective in MSG treated mice after IP but not after oral glucose.

Administration, Oral↗
PubMed1976

Oncornavirus-like particles in baboon type C virus-infected chimpanzee lung cells (SFRE:CL-1).

Intracytoplasmic type A particles were observed in a fetal chimpanzee lung culture (SFRE:CL-1) inoculated with type C virus-containing supernatants from a coculture of baboon placenta and SFRE:CL-1 cells. Budding, immature, and mature type C particles were also noted. In thin section, spike-like structures were rarely detected on budding intracytoplasmic type A particles but were occasionally observed on some immature and mature virus particles. Unlike mouse mammary tumor virus or Mason-Pfizer monkey virus, infected SFRE:CL-1 cells contained no eccentric or rodshaped nucleoids.

Animals↗
PubMed1976

Arbovirus surveillance in six states during 1972.

A virus surveillance project was established and maintained during 1972 along 10 major river drainages in six states. Mosquitoes, biting flies, and blood specimens from sentinel equines were collected during 83 field trip visits to 141 arthropod collecting sites and 22 sentinel locations from April into December 1972. There were 173,074 mosquitoes tested and 303 arboviruses isolated from 11 of 41 species. From 13,388 biting flies tested, 8 arbovirus isolations were obtained in 1 of 5 species. There was no isolation of Venezuelan equine encephalitis (VEE) virus. Western equine encephalitis (WEE) virus isolates were the most numerous and were followed by Turlock, St. Louis encephalitis, Hart Park, California encephalitis, and Bunyamwera (BUN) group viruses. The first isolation of WEE from the mosquito Cullex (Mel). erraticus is reported, as is the extension of the ranges for Buttonwillow virus from California to New Mexico and Texas. Also a single isolation of the BUN group from Culicoides variipennis extends the range of this virus-vector relationship from California to Texas. New distribution records for mosquito species previously unreported for Arizona, Louisana, New Mexico, and Oklahoma are reported. The sentinel burros detected WEE serologic conversions at two sites in New Mexico and at one in Texas. The surveillance project provided state and federal officials with current information on the status of arbovirus activity, including the absence of VEE activity during 1972, and it demonstrated the existence of the potential for WEE epizootics and epidemics throughout a wide geographic area of the Western United States.

Animals↗
PubMed1975

Histochemical, ultrastructural and hormonal studies on the pars distalis of the echidna (Tachyglossus aculeatus).

There were no consistent significant differences between the concentrations of luteinizing hormone (LH) and adrenocorticotrophin (ACTH) in the rostral compared with the caudal zone of the echidna pars distalis. This suggests that LH is secreted by cells containing S-type granules (probably corresponding to secretory vesicles 200-300 nm diameter) which are distributed throughout the gland. Some of the cells containing vesicles 100-200 nm diameter, seen in small numbers in both zones of the gland, may be responsible for the secretion of ACTH. The concentration of pituitary LH is in the range of that found in eutherian mammals, but the concentration of ACTH is lower than that reported for other vertebrates, and this may be linked causally with the remarkably low rate of corticosteroid secretion in the echidna. The absence of significantly increased levels of pituitary LH and ACTH in a chronically orchidectomized and adrenalectomized animal adds to other evidence which suggests that mechanisms involving a negative feedback of steroid hormones on the hypothalamo-hypophysial axis may not be fully developed in the echidna.

Adrenalectomy↗
PubMed1975

Ultrastructure of cleavage stages and preimplantation embryos of the baboon.

The baboon preimplantation stages were examined using light and electron microscopy. Six cases were studied at 2, 3, 4, 5, 7 and 8 days estimated fertilization age. The first 3 specimens were composed of 2, 8 and 24 blastomeres respectively. At 5 days, 30 to 40 cells were counted and more than 60 cells in later stages. Primitive "trophoblast cells" differentiate at 7 days and a crescentic blastocoele appears at 8 days. Shedding of the zona pellucida is not observed in the 7 and 8 day specimens. The preimplantation period is longer in the baboon than in man. C-type viruses are observed in the zona pellucida, in the perivitelline and interblastomeric spaces. Microvilli and caveolae cover ther periphery of the baboon conceptus. As in many other mammals, transformation of the mitochondria, changes in the ribosomes distribution, multivesicular bodies, myelin figures, nucleoli and intranuclear clusters of granules are described in the baboon. Cytoplasmic fibrous strands are not present as in the mouse. Experiments on the influence of hormones and drugs on ultrastructural changes would help to evaluate the importance of biohazards during the early development of primates.

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