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Biomedical subjects

B Mills

Publications and source records attributed to B Mills.

53 records · Page 3Linked to original sources
PubMed1976

Membrane transport in synchronized Ehrlich ascites tumor cells: uptake of amino acids by the A and L system during the cell cycle.

Using the double thymidine block technique. Ehrlich ascites tumor cells (ELD) carried in continuous spinner culture have been synchronized. Simultaneous monitoring of 3H-thymidine incorporation, cell number and mitotic index yielded a cell cycle time of approximately 13.5 hours. This is composed of an S period of 3-4 hours. G2 of 6-8 hours and M of 1-2 hours. No appreciable G1 is present. Ehrlich cells synchronized in this manner were used to investigate the characteristics of two neutral amino acid transport systems during progression through the cell cycle. Unidirectional influx via the Na-dependent system A was studied using C14-alpha-aminoisobutyrate (AIB) as substrate. The Na-independent system L was monitored using 3H-leucine and 14C-cycloleucine as substrates. Transport by the A system was minimal in M and early S. It underwent a three-fold increase during late S and early G2. In mid G2 the transport via this system rapidly dropped and remained low again through M and early S. The intracellular/extracellular ratios of AIB indicate that the system is actively transporting AIB thoughout the cell cycle. The minimum ratios of approximately 3 were achieved during early M and the maximum ratios of approximately 9 were achieved in late S, early G2. The uptake of leucine and cycloleucine by the L system was quite different during the cell cycle. Maximal unidirectional influx by this system occurred during early and mid S period. Upon progression into G2 the transport rate dropped and remained reduced throughout M. Intracellular/extracellular ratios of leucine or cycloleucine were near unity at the peak of the transport activity (early S) and dropped to values of 0.5 to 0.6 throughout the remainder of the cycle. This result indicates that inward transport by the L system is, for the most part, non-active in growing cells.

Amino Acids↗
PubMed1976

Cell cycle dependent changes in potassium transport.

K transport has been investigated during progression of cultured Ehrlich ascites tumor cells through the cell cycle. Using a double thymidine block technique, Ehrlich cells carried in continuous culture have been synchronized, as verified by simultaneous monitoring of cell number, cell volume, 3H-thymidine incorporation and mitotic index. Unidirectional influx, efflux and cell content of K have been monitored throughout the cell cycle. The nature of the pump mediated, ouabain-sensitive K flux and the furosemide-sensitive component of K flux, presumably representing K-K exchange, have also been evaluated. In early S period the ouabain sensitive component, representing the Na-K pump, comprises 52% of the total unidirectional K influx and subsequently declines during G2 period to a minimum of 40% in mid G2. During M and early S the activity again rises. As the ouabain sensitive component becomes maximal in late S period, the furosemide sensitive component diminishes from approximately 30% of the total influx to approximately 10%. The same pattern is observed in the G2 period. As the pump component diminishes, the furosemide sensitive component increases. Furosemide sensitive K efflux has also been monitored and the pattern is equivalent to that observed in the invlux studies. No change in net K flux is observed in the presence of furosemide. This indicates that the furosemide sensitive component represents an exchange component for K. These results are consistent with the conclusion that the alterations in exchange and pump fluxes are physiological events associated with progression of the cell cycle.

Biological Transport, Active↗
PubMed1976

Erythrocyte receptors and thymus-associated antigens on human thymocytes, mitogen-induced blasts, and acute leukemia blasts.

Human thymus cells and blasts from some patients with acute lymphoblastic leukemia (ALL) express similar cell surface properties. This suggests that this type of ALL originates in the thymus or alternatively that these properties of ALL blasts reflect changes occurring during blastogenesis. To test these possibilities, we determined whether mitogen-thymus antigens found on blasts from E+ALL and on normal human thymocytes. E-rosettes of blood T-lymphocytes dissociated at 37 degrees; in contrast, rosettes formed by E+ALL blasts, human thymocytes, and pokeweed mitogen-stimulated blasts were stable at this temperature. Blasts that formed stable rosettes did not have cytoplasmic Ig, indicating that they were T-lymphoblasts. By immunofluorescence and a radiolabeled antibody assay we demonstrated a thymus antigen(s) that was present on the membrane of E+ALL blasts and on normal thymocytes, but not on normal blood T-lymphocytes [TL-like antigen(s)]. This antigen was not expressed on blasts induced by mitogens. The finding that that mitogen-induced blasts form temperature-stable rosettes, but lack TL-like antigen(s), indicates that this antigen is not required for the expression of E-receptors stable at 37 degrees. The results support the concept that E+ALL results from the malignant transformation of thymus cells.

Antigens↗
PubMed1975

Cation permeability and ouabain-insensitive cation flux in the Ehrlich ascites tumor cell.

The components of Na and K flux across the plasma membrane have been investigated in the Ehrlich ascites tumor cell. At intracellular K levels of approximately 100 mM, unidirectional K influx is composed of a ouabain-sensitive component, a ouabain-insensitive, nondiffusional component and a diffusional component. Unidirectional K efflux is composed of an external K-dependent component and a diffusional component. Upon reduction of intracellular K to approximately 50 mM, the external K-dependent component becomes maximal and diminishes upon further reduction of intracellular K. Unidirectional Na efflux is composed of a ouabain-sensitive component, a diffusional component and a saturable, external Na-dependent, ouabain-insensitive component. Unidirectional Na influx may be accounted for by a diffusional component, based on estimates of membrane permeability to Na, membrane potential and Na distribution. This would suggest that the ouabain-insensitive, external Na-dependent Na efflux is not Na--Na exchange. The origin of the cell membrane potential has not been previously established in the Ehrlich ascites cell. From the diffusional components of Na and K flux determined in these experiments, the membrane permeabilities to Na and K have been estimated. These permeabilities, in conjunction with the Na and K distributions across the plasma membrane, predict a cell membrane potential of - 18mV (inside negative). Passive Cl distributions in these cells predict a cell membrane potential of - 21 mV, which is in agreement with previous microelectrode measurements and dibenzyldimethylammonium distributions. The results are therefore consistent with the conclusion that the magnitude and polarity of the cell membrane potential in the Ehrlich ascites cell is dictated primarily by Na and K.

Animals↗
PubMed1975

Reactivity of antihuman thymocyte serum with acute leukemic blasts.

The presence of receptors for sheep erythrocytes (E) on some leukemic lymphoblasts is suggestive but not conclusive evidence for a thymic origin of these lymphoid cells. Normal and leukemic lymphoid populations were therefore examined to determine if the formation of spontaneous E rosettes correlated with the presence of thymus-associated cell surface antigens. Lymphoblasts from four of 12 children with acute lymphoblastic leukemia (ALL) formed spontaneous E rosettes at 4 degrees C and 37 degrees C (E+) and bound rabbit antihuman thymocyte serum, as determined by indirect immunofluorescence and by an indirect radiolabeled antibody assay. The blasts from the other eight children did not form E rosettes at 4 or 37 degrees C (E-) and did not bind antithymocyte serum. Absorption of the antiserum with peripheral blood leukocytes removed all detectable reactivity with normal peripheral blood lymphocytes, normal bone marrow cells, and E- bone marrow cells, but did not remove all reactivity with thymus cells or E+ leukemic blasts. Absorption of the antiserum with thymus from one donor removed all reactivity against thymus cells from another donor. After absorption with normal peripheral blood leukocytes, the antithymocyte serum reacted with E+ leukemic blasts but not with remission lymphocytes from the same patients. Thus, there are at least two distinct thymus-associated antigens-one that is present on T lymphocytes from peripheral blood as well as thymus and another that is present only on normal thymus and on ALL blasts that are identified by their ability to form E rosettes at 37 degrees C.

Adult↗
PubMedDate not supplied

Influence of carteolol and timolol on IOP an visual fields in glaucoma: a multi-center, double-masked, prospective study.

The influences of Carteolol and Timolol eye drops on intraocular pressure (IOP) and visual fields were compared in a multi-center, double-masked, prospective study. Two-hundred and forty eyes of 120 patients were initially included in the study, and 142 eyes of 72 patients fulfilled all the criteria for final statistical analysis. Both drugs significantly reduced IOP. The visual fields in both treatment groups did not change during one year of treatment. In both groups some patients improved slightly, and others deteriorated slightly. This indicates that locally applied beta-blockers may efficiently stop further progression of visual field defects in cases with increased IOP and early visual field damage. There was no difference between Carteolol and Timolol in this regard. The side effects were minimal, and there were no differences in their frequency or intensity in the two treatment groups.

Adolescent↗
PubMedDate not supplied

Home management of URI in children with Down syndrome.

There is an increased risk of upper respiratory infection (URI) for the child compromised by Down Syndrome. Nurses can educate parents to care for the child experiencing mild URI without the need for medical intervention.

Adult↗
PubMedDate not supplied

Comparison of volatile acid number test with enzymatic acetic acid assay for assessment of seafood quality.

Volatile acid number, an official AOAC method for assessing seafood quality, was compared with an enzymatic method for measuring acetic acid. Thirty-eight samples of fresh fish and 23 samples of canned fish were evaluated. The data showed high positive correlations between volatile acid number and enzymatic acetic acid methods; the correlation coefficient was 0.98 for fresh fish and 0.95 for canned fish. Positive correlation coefficients of 0.93 and 0.96 were also associated with samples of fish divided into 2 groups on the basis of acceptable or unacceptable quality, respectively. There was no significant difference between the means for the volatile acid number and enzymatic acetic acid procedures at the 5% level of significance. Decomposition studies on cod and mackerel, representing a lean and fatty fish, respectively, were monitored over 9 days by using the following analyses: volatile acid number, acetic acid, total volatile bases, and thiobarbituric acid. Results of the decomposition studies showed that enzymatic acetic acid levels closely paralleled volatile acid number values in both lean and fatty fish. Total volatile bases was a reliable supplemental measure for evaluating lean seafood quality, whereas thiobarbituric acid was more appropriate for further assessment of fatty fish quality.

Acetates↗