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Biomedical subjects

M Young

Publications and source records attributed to M Young.

At least 325 records · Page 18Linked to original sources
PubMed1985

Identification of restriction fragments from two cryptic Clostridium butyricum plasmids that promote the establishment of a replication-defective plasmid in Bacillus subtilis.

Clostridium butyricum NCIB 7423 carries two cryptic plasmids, pCB101 (6.05 kbp) and pCB102 (7.8 kbp). Sites for the restriction enzymes EcoRI, EcoRV, HindIII, ClaI and PstI have been found in one or both of these plasmids and their relative positions determined. Restriction fragments from both plasmids have been inserted into a vector plasmid (pJAB1) that is able to replicate in Escherichia coli but not in Bacillus subtilis and the recombinant plasmids have been established in E. coli. A 3.3 kbp Sau3A fragment of pCB101 conferred upon the vector the ability to transform both Rec+ and Rec- strains of B. subtilis. Plasmid pRB1, a representative chimaera carrying only the 3.3 kbp Sau3A fragment of pCB101, was successfully transferred from B. subtilis back to E. coli. Plasmid pRB1 was readily lost from B. subtilis in the absence of selection. This evidence, together with the results of hybridization experiments, suggests that pRB1 is present as a weakly replicating autonomous element in B. subtilis. A recombinant plasmid carrying a 2.0 kbp Sau3A fragment of pCB102 underwent integration into the B. subtilis chromosome.

Bacillus subtilis↗
PubMed1985

Placental handling of zinc in the guinea pig.

The distribution of zinc between the mother and the fetoplacental unit, and its placental transfer, were studied using stable and isotopic zinc in unanaesthetized pregnant guinea pigs and an in situ perfusion preparation. The concentration of stable zinc in fetal plasma and skeletal muscle was higher than that in the maternal tissues: 2.0 compared with 1.4 micrograms/ml and 84 with 49 ng/mg dry weight, respectively. The placenta and maternal and fetal liver had similar zinc concentrations: 90, 75 and 88 ng/mg dry weight, respectively. The ability of the placenta to concentrate 65Zn, measured 1 h after a single intravenous injection into the unanaesthetized mother, was comparable with that of the maternal liver. Maternal-fetal mass transfer of zinc was directly related to maternal plasma zinc concentrations from 0.7 to 24.1 micrograms/ml (b = 2 ng X min-1 X g-1 X microgram-1, r = 0.92). At physiological plasma levels, the calculated transfer would supply the fetus with 0.12 mg zinc/day, similar to the accretion rate over the last trimester. Placental transfer of zinc was not influenced by the concentration of zinc in the placental perfusate. Extraction of zinc from the perfusate was also slow, and partly by absorption. Maternofetal transfer of zinc was directly related to both uterine and umbilical blood flows. The high concentration of zinc in the syncytium, relative to both maternal and fetal plasma levels, suggests active uptake at the maternal surface, combined with a slow release into the fetus, down a concentration gradient.

Animals↗
PubMed1985

Electron microprobe analysis of human labial gland secretory granules in cystic fibrosis.

X-ray microanalysis of freeze-dried labial gland cryosections revealed that Na concentration was doubled and the Ca/S concentration ratio was decreased in secretory granules of labial glands from patients with cystic fibrosis (CF) when compared with glands from normal subjects. Other results suggested that the decrease in the Ca/S concentration ratio resulted from an increase in S concentration. These findings imply that mucous granules in labial saliva showed a CF-related increase in Na and S content, and such changes would be expected to affect the rheology of the mucus after exocytosis. In contrast with a previous study in human parotid glands, no evidence was found for CF-related changes in cytoplasmic or nuclear Na, K, and Ca concentrations. Significant elemental differences were found between secretory granules and nuclei and cytoplasm of control cells.

Adolescent↗
PubMed1985

Nerve growth factor: a chemotactic factor for polymorphonuclear leukocytes in vivo.

Previous studies have shown that mouse submandibular gland nerve growth factor (NGF) stimulates chemotactic migration of human polymorphonuclear leukocytes in vitro. The results of the present study demonstrate that subdermal injection of NGF in mice also stimulates rapid and marked chemotactic recruitment of leukocytes. This property of NGF is manifest in the nanomolar range of concentrations, it requires the known serine class protease activity of the growth factor, and it does not require participation of the fifth component of complement. Another, as yet unrecognized, C5-independent pathway must be involved. Chemotactic stimulation of cells involved in the early inflammatory response to injury may help to explain earlier observations that NGF can accelerate the rate of contraction of experimentally induced wounds in mice.

Animals↗
PubMed1985

Stromal and peripheral eosinophilia in cervical carcinoma.

One hundred cases of Stage IB cervical carcinoma treated with radical hysterectomy and pelvic lymphadenectomy at University Hospital of Jacksonville, Florida between 1973 and 1982. Eight patients were found to have tumor stromal eosinophilia on pathology review. Thirteen patients showed eosinophilia in their peripheral smears. Statistical analysis did not reveal a significant recurrence rate in patients with either peripheral or stromal eosinophilia.

Adult↗
PubMed1985

Effect of ascorbic acid on plasma calcium in guinea pigs.

Ascorbic acid (246 mg/kg body weight/day) was administered orally to 9-week old female guinea pigs of the Hartley strain over a period of 20 months. The controls received 40 mg/kg body weight/day of ascorbic acid in the diet. Observations were made on body weight, food and water consumption, plasma ascorbic acid, and the total calcium and ionic calcium levels at various times during the growth of these animals. A second experiment was carried out when the guinea pigs were 18 months old. In addition to the oral intake, they received intraperitoneally 623 mg/kg body weight/day of sodium ascorbate for 6 weeks. With this treatment, the ascorbic acid intake for the test animals was 20 times that for the controls. The plasma ascorbic acid and calcium levels of these animals were measured during the treatment. In the ascorbic acid-treated animals, there was a significant elevation in plasma ascorbic acid level in comparison with the controls, but no substantial differences were observed in the body weight, total calcium or ionic calcium levels in the plasma. The results suggest that the administration of large quantities of ascorbic acid does not affect total calcium or ionic calcium levels in the plasma of these animals.

Animals↗
PubMed1984

An antibody probe to determine the native species of glycinamide ribonucleotide transformylase in chicken liver.

Antibody probes of Western blots [Renart, J., Reiser, J., & Stark, G. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 3116] of chicken liver homogenates under various conditions revealed that glycinamide ribonucleotide transformylase can be rapidly proteolyzed in such homogenates. These findings, along with molecular weight measurements by ultracentrifugation, identify the true form of glycinamide ribonucleotide transformylase as a monomeric protein of 117000 daltons. This protein has been purified 400-fold in 44% yield from chicken liver in one step on an affinity column of 10-formyl-5,8-dideazafolate-Sepharose. Native glycinamide ribonucleotide transformylase retains full activity after proteolytic cleavage to a form (Mr 55000) similar to fragments seen in the Western blot of the homogenates. This phenomenon may be responsible for the previous identification of glycinamide ribonucleotide (GAR) transformylase as a dimer of 55000-dalton subunits. Similar analyses using antibodies to 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase [Mueller, W. T., & Benkovic, S. J. (1981) Biochemistry 20, 337] and trifunctional enzyme [Smith, G. K., Mueller, W. T., Wasserman, G. F., Taylor, W. D., & Benkovic, S. J. (1980) Biochemistry 19, 4313] confirm that these two proteins were isolated in their native forms.

Acyltransferases↗
PubMed1984

A rapid technique for measuring leukocyte chemotaxis in vivo.

A modification of connective tissue air bleb technique was used to develop a model system in inbred strains of mice for the study of chemoattractants in vivo. The method was developed using the well characterized n-formylated chemotactic peptide, f-Met-Leu-Phe, as the positive control. Injection of 0.1 ml of f-Met-Leu-Phe solutions from 10(-7) to 10(-10) M resulted in an influx of polymorphonuclear leukocytes within 2 h. Study of the kinetics of the response showed that the number of infiltrating cells reached a peak within 8 h and slowly declined over a 2-day period. The predominant infiltrating cell type during the first 24 h was the polymorphonuclear leukocyte. Between 24 and 48 h the polymorphonuclear leukocytes were replaced by monocytes. By utilizing an inbred mouse strain (DBA-1J and 2J) sufficient or deficient in C5 it was possible to distinguish compounds that were directly chemotactic from those that worked indirectly, or whose chemotactic potential could be enhanced by generation of the chemotactic complement split product C5a. The method was found to be technically simple, reproducible and semi-quantitative and represents a good model system to facilitate the comparison of chemotactic responses in vivo and in vitro.

Animals↗
PubMed1984

Functional and anatomic correlates of markedly abnormal stress tests.

The functional state and coronary anatomy of 120 patients evaluated primarily because of a markedly positive ischemic exercise stress test (greater than 2 mm ST depression) is presented. Twenty-seven patients were asymptomatic (group A), 36 patients (group B) had type I angina (Canadian classification) and 57 patients (group C) had angina with only minor limitations (type II angina). All patients underwent exercise stress testing (Bruce protocol) within 2 months of cardiac catheterization. No significant intergroup differences were observed in exercise variables including time of onset of ischemia, maximal heart rate achieved, rate-pressure product, duration of exercise or mean change in blood pressure. Two patients in group A had normal coronary arteriograms. Comparison of the remaining asymptomatic patients in group A with patients in groups B and C revealed no significant differences in the number of coronary arteries involved, main left coronary artery disease, coronary score or the frequency of collateral circulation. In group A, 18% of collateral vessels were in jeopardy compared with 52% in groups B and C (p less than 0.05). Triple vessel disease was present in 57% and left main coronary artery disease in 16% of the total group. The only exercise variable useful in identifying patients with severe coronary disease was an abnormal exercise blood pressure response. This study indicates that a markedly ischemic stress test, regardless of the functional state of the patient, identifies patients, including those without symptoms, who have severe coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Gene amplification in Bacillus subtilis.

A strain of Bacillus subtilis that carries in its genome a staphylococcal chloramphenicol acetyltransferase gene (from pC194) responds to growth at different concentrations of chloramphenicol by an alteration in the number of copies per genome of the sequences encoding the gene. Growth at 20 micrograms chloramphenicol ml-1 results in a 15-fold amplification of the sequences, whereas growth in the absence of chloramphenicol results in their loss. The mechanism of in situ amplification probably has much in common with that involved in 'R factor transitioning'. The hybridization procedures that have been used for accurately determining the number of copies of the amplified DNA sequences are potentially useful for plasmid copy number determination. The findings reported here also provide a potentially useful alternative to more conventional cloning strategies that are based on autonomous plasmids in B. subtilis. The particular advantages that can be envisaged include enhanced stability of the cloned sequences and control of the number of copies that are present.

Bacillus subtilis↗