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Biomedical subjects

R Kelly

Publications and source records attributed to R Kelly.

At least 163 records · Page 9Linked to original sources
PubMed1983

Characterization of cDNA clones specific for sequences developmentally regulated during Dictyostelium discoideum spore germination.

Spore germination in the slime mold Dictyostelium discoideum was used as a model to study the developmental regulation of protein and mRNA synthesis. Changes in the synthesis of these macromolecules occur during the transition from dormant spore to amoebae. The study of the mechanisms which regulate the quantity and quality of protein synthesis can best be accomplished with cloned genes. cDNA clones which hybridized primarily with mRNAs from only spores or germinating spores and not with growing amoebae were collected. Three such clones, denoted pLK109, pLK229, and pRK270, were isolated and had inserts of approximately 500, 1,200, and 690 base pairs, respectively. Southern blot hybridization experiments suggested that each of the genes is present in multiple copies in the D. discoideum genome. RNA blot hybridizations were performed to determine the sizes of the respective mRNAs and their developmental regulation. The mRNA that hybridized to pLK109 DNA was present predominantly in spores and at 1 h after germination but was absent in growing amoebae. Its concentration dramatically dropped at 3 h. The mRNA present in spores is apparently larger (approximately 0.5 kilobase) than in the later stages of germination (0.4 kilobase), indicating processing of the RNA during germination. The mRNA that hybridized to pLK229 DNA was approximately 1.0 kilobase and was present in very low amounts during growth. Its concentration rose until 1 h after spore germination and decreased thereafter. pRK270-specific RNA was approximately 2.7 kilobases and was found predominantly at 1 h after germination. It was present in lower concentrations at 2 and 3 h after germination and was absent in spores and amoebae. In vitro translation of mRNA selected from 1-h polyadenylated RNA which was hybridized to pLK109 or pLK229 DNA gave proteins of molecular weights consistent with the sizes of the mRNAs as determined by the RNA blot analysis.

Cloning, Molecular↗
PubMed1983

Comparison of the levels of the 21S mitochondrial rRNA in derepressed and glucose-repressed Saccharomyces cerevisiae.

A cDNA preparation, synthesized by using Saccharomyces cerevisiae mitochondrial RNA as template and oligodeoxythymidylic acid as primer, was found to specifically hybridize to the mitochondrial 21S rRNA by the following criteria: (i) it hybridizes only to the 21S RNA species in mitochondrial RNA and not to RNA from a [rho0] mutant, and (ii) it hybridizes to fragments in restriction digests of mitochondrial DNA that contain the 21S rRNA gene but not to nuclear DNA. This cDNA was used as a probe to demonstrate that a 2.6-fold decrease in the cellular level of the mitochondrial large rRNA is associated with glucose repression of mitochondrial function in S. cerevisiae. A corresponding decrease in the level of mitochondrial DNA was not observed.

DNA↗
PubMed1981

Mexiletine in plasma by high pressure liquid chromatography.

We report here a novel high pressure liquid chromatographic (HPLC) technique for use in therapeutic monitoring of the primary amine antiarrhythmic drug mexiletine in plasma samples. Mexiletine and its structural analogue, the internal standard Ko 768, are extracted with heptane after alkalinization of the sample. The extracts are evaporated to dryness, reconstituted, and injected into a liquid chromatograph equipped with an octadecylsilane reversed phase column using an acetonitrile/acetate buffer mobile phase. Detection is by ultraviolet absorption at 254 nm. The method is linear from 0.2 to 5.0 microgram/ml; the coefficient of variation ranges from 5 to 10% within the therapeutic range. The drug is stable for at least 99 days in samples stored at -20 degrees C. Our HPLC results showed good agreement with a popular gas liquid chromatographic method (14), and there are few incidents of interference from common drugs. The method is convenient for any laboratory equipped with standard liquid chromatographic equipment and is suitable for automation.

Chemical Phenomena↗
PubMed1981

Post-traumatic syndrome: another myth discredited.

Further studies confirm the authors' previous contention that patients suffering from the post-traumatic syndrome (PTS) do recover from this syndrome and return to full-time work before litigation is settled. Failure to have returned to work by the time of settlement indicates a bad prognosis, and such patients rarely return to work afterwards; the older the patient the worse the prognosis.

Adolescent↗
PubMed1979

Multiple sclerosis in southern Europe. I: Prevalence in Sicily in 1975.

Previous reports on large population groups have suggested that the prevalence of multiple sclerosis (MS) in Sicily and southern Italy is low, of the order of 4-8 per 100 000. In contrast, immigrants from Italy resident in Greater London, many of whom are from southern Italy and Sicily, had a hospitalised MS prevalence similar to that found among people born in the United Kingdom (1960-72). The present study shows that in Enna city (population 29 000) in central Sicily, the prevalence of probable MS was 53 per 100 000, which is of the same order of magnitude as has been reported from the United Kingdom and northern Europe. The high prevalence of MS found in Enna city may be due, at least in part, to the fact that the population studies was small. Because Enna is on high ground, similar studies are being undertaken in two small coastal towns of Sicily.

Adult↗
PubMed1978

Characteristics of red blood cell survival from subjects with hereditary elliptocytosis.

Hereditary elliptocytosis is an intrinsic red cell abnormality and 12% of elliptocytic individuals demonstrate hemolysis. Using tracer kinetic methodology (51Cr labeled RBC's) the destructive phase of erythropoesis was assessed in two healthy subjects receiving labeled donor red blood cells from individuals with hereditary elliptocytosis. The red blood cell survival time of transfused elliptocytes was significantly decreased in both recipients, with a survival half-time (T 1/2) of 19 days in one recipient and 20 days in the other (N 27 days). Abnormal splenic sequestration was also demonstrated. The decreased survival of transfused cells suggests that caution should be exercised in utilizing patients with hereditary elliptocyosis as donors in blood banking operations even in the absence of evidence of hemolysis.

Blood Transfusion↗
PubMed1978

Delayed hypersensitivity and neutrophil chemotaxis: effect of trauma.

To investigate alterations in host defense produced by trauma, skin testing with five standard recall antigens was done on admission and weekly on 53 patients with blunt trauma and seven with penetrating missile injuries, who then were classified as normal (N), 2 or more positive responses; relatively anergic (RA), one positive response; or anergic (A), no response. Neutrophil chemotaxis was tested 145 times in 32 patients. Degree of injury was assessed by assigning one point to pelvic fracture, long-bone fracture, head, chest, or abdominal injury, to a maximum of five. The A and RA patients had greater trauma, 3 vs. 1.6 for N, and a significantly increased rate of sepsis (p less than 0.005) and mortality (p less than 0.05). Incidence of anergy depended upon age and extent of trauma. Neutrophil chemotaxis in A and RA patients was significantly (p less than 0.001) worse at 96.7 +/- 2.4 mu and 99.8 +/- 1.7 mu compared to N, 113.2 +/- 1.7 mu, and controls 121 +/- 4 mu. With recovery, chemotaxis returned to normal. It is concluded that failure of delayed hypersensitivity responses follows trauma, is related to the severity of injury and age of patient, and is associated with an abnormality of neutrophil chemotaxis and increased rate of sepsis.

Adolescent↗