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Biomedical subjects

G R Smith

Publications and source records attributed to G R Smith.

At least 325 records · Page 18Linked to original sources
PubMed1976

Partial characterization of somatomedin bioactivity in term human amniotic fluid.

Somatomedin (SM) activity in human amniotic fluid (AF) was partially characterized. Aliquots of pooled AF, obtained at term gestation, were acidified to pH 2.3 and sequentially studied by ultrafiltration on various membranes, Sephadex gel filtration, and starch gel electrophoresis (SGE). SM activity was measured by a rat cartilage bioassay. SM activity in AF, under these conditions, was present in several stable indicated molecular size (IMS) forms; large (greater than 45,000) and small (near 10,000). The small SM was found in basic and acidic forms after SGE. These studies suggest that SM activity in term human AF is somewhat similar to SM in unextracted plasma. In addition, immunoreactive GH and insulin were measured in AF but at lower concentrations than usually found in plasma. After chromatography of AF, GH was found in large and small IMS forms, whereas most of the insulin was found in the monomer insulin IMS area.

Amniotic Fluid↗
PubMed1976

Size heterogeneity of human serum somatomedin.

Somatomedin (SM) in unextracted human serum was studied by Sephadex chromatography, starch gel electrophoresis, and in vitro SM bioassays. Repeated rechromatography of the various serum fractions revealed SM activity in a variety of indicated molecular size (IMS) areas; greater than 90,000, (very large); 90,000-20,000, (large); 20,000-9000, (intermediate); 9000-2000, (small); and less than 2000, (very small). Chromatography of unextracted serum, at pH 7.4, revealed 65% of SM as very large SM. Most of this very large SM remained stable at neutral pH; less than 25% appeared in smaller molecular sizes after acid eluent rechromatography. The latter significantly reassociated with other serum proteins in alkaline conditions. The large IMS SM was relatively stable on rehcromatography, whereas most of the intermediate IMS SM was converted to acidic small IMS SM proteins. The small IMS SM was stable, as a basic protein, after repeated acidic rechromatography. Most of the very small IMS SM occurred in a molecular size of less than 500. These results suggest the presence of multiple molecular size forms of SM in unextracted serum. Some of the larger SM represents an SM-serum protein aggregation. The acidic SM, with a molecular size near insulin, may be derived from a larger SM. The very small SM may be a nonpolypeptide substance(s).

Acromegaly↗
PubMed1976

Optimal tomographic technique to demonstrate common bile duct stones. An in vitro study.

Six degree and 10 degree circular modes represent the optimal methods available for intravenous cholangiography with tomography within the technical limitations and constraints outlined in this study. The 10 degree mode is superior in the presence of superimposed gas. Ten degree linear tomography is an efficient method for determining the level of the common bile duct but is not the optimal method for obtaining image detail. Thin secretion unidirectional or pleuridirectional modes are occasionally helpful in delineating fine details. The zone of focus is very narrow, permitting very limited sampling within the usual zone of interest. These modes are inefficient in determining the level of the duct and produce less useful image detail than 10 degree circular tomography for ducts of normal, or slightly larger than normal diameters. They are seldom indicated as the primary modality in tomography of the common bile duct.

Gallstones↗
PubMed1976

A case of cerivco-thoracic anomaly simulating traumatic fracture-dislocation.

A patient who sustained severe head trauma had a simulated C7, T1 fracture dislocation. Anteroposterior tomography of the cervico-thoracic junction disclosed anomalous vertebral-costal articulations. The rotation of the spine and the abnormal posterior articulations were secondary to anterior costal bridging. Tomography of the costo-vertebral facets in patients with unusual rib configurations may help delineate cases of thoracic spine rotation.

Adolescent↗
PubMed1976

Virulence of established vaccine strains and artificially passaged field strain of Mycoplasma mycoides subsp mycoides.

The virulence of Mycoplasma mycoides for mice, which appears to parallel virulence for cattle, was assessed in respect of four vaccine strains well known for their use in the control of contagious bovine pleuropneumonia. The T1 strain was slightly more virulent than V5, and both were much more virulent than F and KH3J, which could not be distinguished from each other. There was no significant difference between cultures of the T1 strain supplied by three different vaccine-producing laboratories, The mousevirulence test was also used to study the effect of serial passage in artificial systems on virulent field strains of M mycoides; two such strains underwent no appreciable change in virulence during many passages in chick embryos or in mice, although the same strains, and two others, were readily attenuated by repeated subculture in broth. With one strain of M mycoides there was evidence that the total number of subcultures in broth over a given period was more important than the duration of each subculture.

Animals↗
PubMed1975

Startle reaction to air-bag restraints.

Air bags in vehicles constitute a means of passive restraint for individuals involved in auto accidents. There is fear, however, that the inadvertent nonaccident-connected deployment of one of these air bags might substantially interfere with the handling of a vehicle in which such deployment occurred. We have found that while physiologic and physical evidence of startle accompanies such unexpected deployment, good control of the vehicle continues to be exercised by the test subjects under the conditions of our experimental protocol.

Accident Prevention↗
PubMed1975

Oligo(A) not coded by DNA generating 3'-terminal heterogeneity in a lambda phage RNA.

An RNA species from Escherichia coli infected with phage lambda was purified by hybridization to lambda 1-strand DNA and shown to have variable length. This variability was due to a variable number of adenylate residues attached to the 3' end of the molecule. Pancreatic RNase treatment of the RNA-DNA hybrid removed the 3'-terminal adenylate residues, generating a homogeneous RNA molecule terminating with -Up. The results indicate the presence of adenylate residues not coded by the DNA template at the terminus of this transcript from intact cells.

Adenine Nucleotides↗
PubMed1975

Clostridium botulinum in the lakes and waterways of London.

Mud samples collected during 1974 from a large proportion of the lakes and waterways of London were examined for Clostridium botulinum. Of 69 such sites, 50 (72.5%) contained at least one type of the organism. Of the 50 positive sites, 31, 12, 1 and 10 contained, respectively, types B, C, D and E. Most of the demonstrations of type B required trypsinization of culture filtrates. An examination of 7 lakes in Edinburgh, made for the purpose of comparison, showed that 4 contained type B and one type C. An analysis of the results gave quantitative information on the value of (1) resampling apparently negative lakes, (2) the use of both heated and unheated culture inocula, and (3) trypsinization of culture filtrates.

Animals↗
PubMed1975

A somatomedin assay using normal rabbit cartilage in clinical studies.

Somatomedin (SM) is a growth hormone (GH) dependent biological growth factor in serum. A SM assay, using mechanically sliced discs from young normal rabbit costal cartilage was developed and evaluated. This assay is as sensitive and precise, while much less laborious and costly, than the hypophysectomized rat cartilage SM assay. The elevated serum SM levels in patients with acromegaly returned to normal in two patients who were cured, and remained elevated in four incompletely treated patients. The low serum SM levels in five GH deficient patients were increased to normal after treatment with human GH. SM levels were normal in 10 patients with normal GH levels and short stature due to various causes. SM levels in serum were very low in patients with chronic renal insufficiency; the mean SM level increased significantly after renal transplantation, however, it increased only minimally after hemodialysis. SM levels were subnormal in 14 patients with sever chronic liver disease. One patient with severe acute liver disease had low serum SM levels which increased after clinical recovery. These results further suggest that the liver produces SM, while the relationship of the kidney and SM is not clear.

Acromegaly↗
PubMed1975

Hemorrhage from the gastroesophageal junction. A cryptic angiographic diagnosis.

The angiographic localization of gastroesophageal-junction hemorrage emanating from the left inferior phrenic artery (which originated from the abdominal aorta) is described. The diagnosis was established after conventional selective celiac and left gastric arteriography failed to demonstrate extravasation. The arteriographic evaluation of upper gastrointestinal hemorrhage requires consideration of the variable arterial distribution to the gastroesophageal junction and an awareness of the variable causes of dense opacification (including superimposed adrenal glands) that may mimic extravasation.

Adult↗
PubMed1975

Inhibitory action of oestrogen on calcium-induced mitosis in rat bone marrow and thymus.

In the male rat injections of CaCl-2 and MgCl-2 stimulated mitosis in bone marrow and thymus tissue. The magnesium salt was also mitogenic in the normal female, but calcium only exerted its mitogenic effect after ovariectomy. Oestradiol, but not progesterone replacement therpy abolished calcium-induced mitosis in the ovariectomized rat. The inability of calcium to stimulate cell division was also apparent in the thyroparathyroidectomized female rat, suggesting the oestradiol blockage did not operate via some indirect action on the calcium homeostatic hormones calcitonin or parathyroid hormone. When thymic lymphocytes derived from male or female rats were isolated and maintained in suspension, increased calcium or magnesium concentrations in the culture medium stimulated the entry of cells into mitosis. Addition of oestradiol to the culture medium abolished the mitogenic effect of increased calcium levels, but had no effect on magnesium-induced proliferation. These experiments suggested that oestradiol might act at the cell surface to prevent the influx of calcium but not magnesium ions into the interior of the cell and thus to block the sequence of biochemical events which led to the initiation of DNA synthesis and culminate in mitosis.

Animals↗