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Biomedical subjects

D L Miller

Publications and source records attributed to D L Miller.

At least 487 records · Page 27Linked to original sources
PubMed1977

Translation in Escherichia coli mini-cells containing hamster mitochondrial DNA-Co1E1 - Ampr recombinant plasmids.

Hamster mitochondrial DNA is cleaved into two fragments (4.2 and 11.4 kilobase pairs of DNA (kb)) by the restriction enzyme, Eco RI. Recombinant DNA molecules formed in vitro between an Escherichia coli plasmid, Co1E1 - Ampr, and Eco RI-digested hamster mitochondrial DNA were transformed into E. coli K12. The translation products of the parent plasmid, Co1E1 - Ampr, and recombinant plasmid DNAs containing (i) the 4.2 kb mitochondrial DNA fragment and (ii) the 11.4 kb fragment were characterized on sodium dodecyl sulfate-polyacrylamide gels using bacterial mini-cell lysates. The Co1E1 - Ampr plasmid specifies at least six polypeptides whose structural genes comprise 56% of the plasmid DNA. Insertion of hamster mitochondrial DNA at the Eco RI site of the plasmid alters the relative rate of synthesis of these six polypeptides and induces the occurrence of a new band on sodium dodecyl sulfate-polyacrylamide gels which is probably not specified by the inserted mitochondrial DNA sequences.

Ampicillin↗
PubMed1977

Transcription and translation of cloned Drosophila DNA fragments in Escherichia coli.

The expression of three unique DNA fragments from Drosophila melanogaster which have been inserted into Escherichia coli (E. coli) via the plasmid, pSC 101, was studied. The hybrid plasmid DNA molecules containing Drosophila DNA were transformed into the minicell producing strain of E. coli, X1411. Drosophila DNA-directed RNA synthesis was studied by hybridizing newly synthesized RNA isolated from the minicells with various DNA fragments which were immobilized on nitrocellulose filters. RNA was synthesized as readily from the inserted Drosophila DNA as from the original bacterial plasmid, pSC 101. In one case, transcription appeared to be initiated preferentially on one of the two strands of a Drosophila DNA fragment regardless of the orientation of that Drosophila DNA fragment with respect to the pSC 101 sequences. Two of the three Drosophila DNA fragments did not induce the synthesis of new polypeptides in minicells as detected by autoradiography of [35S]methionine-labeled polypeptides on polyacrylamide gels. The third Drosophila DNA fragment caused the synthesis of one additional polypeptide of 29 000 daltons. When an 8200 base pair portion of the third inserted Drosophila DNA (63% OF THE TOTAL Drosophila insertion) was removed by digestion with the restriction enzyme, Eco R1, this new polypeptide was no longer synthesized by minicells containing the remaining Drosophila DNA. When the 8200 base pair fragment was placed back into its parent plasmid as an inversion, the new polypeptide did not reappear. In addition, the presence of some, but not all, of the Drosophila DNA insertions affected the relative synthesis of the six polypeptides coded for by the parent plasmid, pSC 101.

Animals↗
PubMed1977

Cromolyn sodium nasal solution in the prophylactic treatment of pollen-induced seasonal allergic rhinitis.

A large-scale multicenter investigation was undertaken in 3 cities with comparable pollen seasons and atmospheric pollen concentrations in order to obtain more definite information about the safety and efficacy of cromolyn sodium in the treatment of pollen-induced seasonal rhinitis. The 9-wk double-blind study was conducted in 104 patiets in Pittsburgh, Pa., Cleveland, Ohio, and Louisville, Ky., during the 1975 ragweed season. It indicated that a nebulized 4% aqueous solution of cromolyn sodium is effective in reducing sneezing, rhinorrhea, nasal congestion, and ocular irritation in ragweed hay fever patients. The efficacy of the drug was notable despite the fact that patients used an average of 52 mg instead of the recommended 62.4 mg daily. Cromolyn sodium did not appear to have a significant effect on transseasonal antiragweed IgE (IgEAR) levels. Patients acceptance of the cromolyn nasal solution was good, and there were no significant adverse reactions. The side effects, which were distributed equally between the drug and placebo groups, were mild and of limited duration.

Administration, Intranasal↗
PubMed1977

Intestinal absorption of glycine and glycyl-L-proline in the rat.

1. Absorption of [3H]glycine and [14C]-glycyl-L-proline at concentrations between 0-5 and 4 mmol/l was studied by perfusion in vivo of rat jejunal and ileal segments. Absorption was defined as net removal of radioisotope from the perfusate. Radioactivity assays and amino acid analyses were performed on perfusates and on mucosal tissue samples obtained from the perfused segments. 2. At the concentrations studied, absorption rates of glycine and glycylproline were proportional to concentration. Ileal rates were approximately 60% of jejunal rates. Glycylproline absorption was slightly faster than glycine absorption and was associated with the appearance in the perfusate of free glycine and proline in the ratio approximately 3:1. Intraluminal hydrolysis was insufficient to account for the amounts of free amino acids found and glycylproline hydrolase activity at the brush border is known to be minimal. 3. Glycylproline absorption apparently occurred by transport of the intact peptide followed by its intracellular hydrolysis. However, more than one-third of absorbed glycine and one-eighth of absorbed proline returned to the lumen as free amino acid. This reflux of glycine and proline was not proportional to their concentrations in the mucosa.

Animals↗
PubMed1977

Plasma protein synthesis by isolated rat hepatocytes.

A system of preparation of rat hepatocytes with extended viability has been developed to study the role of hormones and other plasma components upon secretory protein synthesis. Hepatocytes maintained in minimal essential medium reduced the levels of all amino acids in the medium except the slowly catabolized amino acids leucine, isoleucine, and valine, which steadily increase as the result of catabolism of liver protein. Although the liver cells catabolize 10-15% of their own protein during a 20-h incubation, the cells continue to secrete protein in a linear fashion throughout the period. The effects of insulin, cortisol, and epinephrine on general protein synthesis, and specifically on fibrinogen and albumin synthesis, have been tested on cells from both normal rats and adrenalectomized rats. Cells from normal animals show preinduction of tyrosine amino transferase (TAT), having at the time of isolation a high level of enzyme which shows only an increase of approximately 60% upon incubation with cortisol. In contrast, cells from adrenalectomized animals initially have a low level of enzyme which increases fourfold over a period of 9 h. The effects of both epinephrine and cortisol on protein synthesis are also much larger in cells from adrenalectomized animals. After a delay of several hours, cortisol increases fibrinogen synthesis sharply, so that at the end of the 20-h incubation, cells treated with hormone have secreted nearly 2.5 times as much fibrinogen as control cells. The effect is specific; cortisol stimulates neither albumin secretion nor intracellular protein synthesis. The combination of cortisol and epinephrine strongly depresses albumin synthesis in both types of cells. Insulin enhances albumin and general protein synthesis but has little effect on fibrinogen synthesis.

Adrenalectomy↗
PubMed1977

Thermoanalytical probes for the analysis of physical properties of stratum corneum.

Thermomechanical analysis (TMA) measurements were used to characterize the physical properties of normal and treated stratum corneum. TMA measures changes in the overall mechanical and dimensional properties of the material as a result of temperature-induced transformations such as lipid melting, protein conformational changes, and glass transitions. TMA indicates several softening transitions in normal human stratum corneum which occur at about 50, 150, 260 degrees C. Differential scanning calorimetry and thermomechanical analysis studies show that the 50 degrees C softening is related to lipid melting as well as protein side chain motion while the other observed transitions appear to result from a change in state of the protein organization and decomposition, respectively. These particular parameters are sensitive to changes in composition and macromolecular structure of the stratum corneum brought about by disease and chemical alteration. Shifts in the temperature of the second softening transition are observed between normal stratum corneum and stratum corneum treated with a retinoic acid product, occlusive therapy, petrolatum, propylene glycol-ethanol, and normal saline. These shifts imply a possible alteration of the higher-level organization of the keratin in the stratum corneum.

Calorimetry, Differential Scanning↗
PubMed1977

Attendance at a London casualty department.

Patients who attended the casualty department of the Middlesex Hospital during one week in 1973 were interviewed. A predominantly young and working population used the department. Relatively few patients lived close to the hospital but many worked nearby. One third of all attendances were by patients who had been asked to return by casualty doctors. About half the new patients came of their own accord; the next largest group had been sent directly from work by an employer or occupational health service. Half the patients came with injuries, many of them superficial, although there were also serious accident cases. One fifth of the patients had no general practitioner whom they could consult. Age and geographical mobility were related to whether or not patients were registered with a general practitioner. The main reasons for not consulting a general practitioner were that patients felt they needed hospital treatment or that it was more convenient to attend the casualty department. It is suggested that the view that casual attenders with relatively trivial complaints should be encouraged to go to a general practitioner is not always applicable since social as well as medical circumstances determine whether or not patients decide to visit casualty.

Emergency Service, Hospital↗
PubMed1977

Proliferation rate and transit time of mucosal cells in small intestine of the diabetic rat.

Streptozotocin-induced diabetes in the rat alters intestinal function, causes hyperphagia and arrests body growth, but stimulates intestinal growth, particularly in the mucosa. Therefore we measured several indices of epithelial cell proliferation to gain insight on possible factors responsible for the increased mucosal cell mass in the small intestine. We examined epithelial cell proliferation in upper jejunum and terminal ileum of weight-matched control and diabetic rats pair fed or eating ad libitum. Cell proliferation was measured two ways: (1) isolating whole crypts 1 hr after injection of [3H]thymidine ([3H]TdR) and calculating disintegrations per minute per crypt (dpm per crypt), and (2) autoradiography of mucosal sections to obtain labeled cells per crypt, total cells per crypt-villus column, and cell migration rates. Autoradiography showed diabetes: (1) increased cell number of crypt-villus columns and increased labeled cells per crypt section, primarily jejunum, and (2) did not alter cell migration except for an increase in the ileum of diabetics eating ad libitum. Cell proliferation measured as dpm per crypt virtually doubled in diabetics in both segments regarless of dietary regimen. Dpm per crypt is a three-dimensional measurement based on the whole crypt. The increase in cell number and labeled cells per crypt in jejunal sections is also consistent with increased cell division, but shows a much smaller effect. The nature of the histological technique (two-dimensional) limits its usefulness for measuring morphological changes, and this may explain the discrepancy. Hence, the primary effect of diabetes is increased DNA synthesis (dpm per crypt) and this appears to be the main explanation for stimulated mucosal growth.

Animals↗
PubMed1976

DNA-directed in vitro synthesis of elongation factor Tu.

The in vitro synthesis of EF-Tu was studied using the transducing phage lambdarifd18 DNA as template. The EF-Tu synthesized was identified by its immunological properties, gel analysis, and its ability to interact with GDP and EF-Ts. Two other unidentified polypeptides were also precipitated from the incubation mixture by EF-Tu antiserum. The synthesis of total EF-Tu immunoprecipitable material was depressed about one-half by guanosine-5'-diphosphate-3'-diphosphate which was shown to inhibit the transcription process.

Antibodies↗
PubMed1976

Completeness of statutory notification for acute bacterial meningitis.

Several different sources of data, including statutory notifications, were used to identify cases of acute bacterial meningitis in childhood in a defined population. Only half the cases of meningococcal meningitis and less than one quarter of ofther types of bacterial meningitis had been notified. Notified cases differed from the remainder with respect to causative organism, age, outcome, and type of hospital of admission. Thus notifications are an unreliable measure of incidence for this disease, and studies of infectious disease based on notified cases alone should be interpreted with considerable reserve. It is suggested that infectious-disease surveillance should be both clinical and microbiological and that data from different sources need to co-ordinated. The reason for reporting each disease (or organism) should be specified and and reviewed periodically.

Bacterial Infections↗
PubMed1976

Reconstitution of a purified acetylcholine receptor.

Dialysis of the purified acetylcholine receptor from Torpedo californica electroplax with lipids from the same organ results in a vesicular membrane system in which the receptor is embedded in the bilayer and oriented so that most of the neurotoxin-binding sites appear to be on the outer surface. The reconstituted vesicles are chemically excitable by acetylcholine and carbamylcholine, as measured by 22Na+ efflux. The excitability is specifically blocked by the antagonist alpha-bungarotoxin. These results demonstrate that the purified reconstituted receptor system not only can specifically bind neurotransmitter but can also trigger ion translocation. It therefore has the properties necessary to effect postsynaptic depolarization in vivo.

Acetylcholine↗
PubMed1976

Monitoring communicable disease: vaccination programmes.

The success of vaccination as a means of disease prevention depends on its appropriate application and its reputation with the profession and the public. Surveillance, by providing accurate information on effectiveness and the frequency and nature of hazards, is essential to this purpose. Several factors that influence the success and safety of vaccination programmes are discussed. The essential elements of a vaccine surveillance scheme are outlined with special reference to experience derived from monitoring vaccines in current use.

Antibodies, Viral↗