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Biomedical subjects

J P Mitchell

Publications and source records attributed to J P Mitchell.

At least 55 records · Page 3Linked to original sources
PubMed1986

Immunocytochemical localization of proteins in differentiating tissues of Pisum sativum.

Although there may be documented morphological changes during development, it is obvious that important changes in protein content occur in a vascular plant during the several stages of differentiation. In the absence of the latter information, an approach has been established for the localization of antigenic proteins in developing tissues of Pisum sativum. Monoclonal antibodies were raised to proteins extracted from pea internode tissue, and employed for the localization of three proteins in tissue sections. One of the proteins has two polypeptide subunits with molecular weights of 25,000 and 40,000 daltons, and the antibody binds to both of them. The three monoclonal antibodies produce different patterns of cellular localization in the tissue sections, as visualized by indirect immunocytochemical labeling. In another series of analyses, quantitative and qualitative differences in the protein contents of apical shoot tissue and mature internode shoot tissue have been found. These studies were based on the use of Western blots with both polyclonal (rabbit) antibodies and monoclonal (mouse) antibodies.

Antibodies, Monoclonal↗
PubMed1983

Quantitative changes in the degree of chromatin condensation during the cell cycle in differentiating Pisum sativum vascular tissue.

Fixed tissue from the base of the fourth internode above the cotyledons of Pisum sativum plants were Feulgen-stained for DNA. In squash preparations three cell types: xylem vessel elements, phloem fibres and phloem sieve tube elements were identified. Measurement of Feulgen absorbance values in 0.5 X 0.5 microns measuring points across each nucleus were obtained with a scanning cytophotometer. Condensed chromatin was defined as any measuring point having an absorbance value greater than 0.32. Calculating 'percent condensed chromatin' as the percentage of the total nuclear DNA contained in those densely stained points, the pattern of change in this parameter during interphase in each cell type was observed. A generally similar pattern occurs in all three cell types. Percent condensed chromatin decreased from about 45% to 12% during G1, increased rapidly to the end of S, decreased during G2 and the following G1 to increase again during the subsequent S phase.

Cell Cycle↗
PubMed1983

Nuclear and nucleolar protein during the cell cycle in differentiating Pisum sativum vascular tissue.

Squash preparations of Pisum sativum fourth internode tissue were stained with a combined Feulgen and dinitrofluorobenzene (DNFB) procedure. Nuclei from differentiating xylem vessel elements, phloem sieve tube elements and phloem fibres were measured for their DNA and protein contents with a Zeiss scanning cytophotometer linked to an interactive computer system. Nuclei were examined from both slowly growing and more rapidly growing internodes. A computer program was constructed to calculate nuclear protein alone as well as the ratio of DNFB (protein) to Feulgen (DNA) staining in each 0.5 X 0.5 micron measuring point. Nuclei were assigned to each of ten interphase fractions based on DNA content, nuclear area and percent condensed chromatin. There was a slight increase of nuclear protein during G1, a gradual increase in S, and a continued, often sharper, rise as G2 proceeded. In all three cell types, there was, on the average, a higher protein content throughout interphase in nuclei from the more rapidly growing internodes than from the slower growing ones. A population of fibre nuclei designated G0, however, differed from phloem and xylem G0 nuclei in the pattern of protein change. The nucleolar protein/DNA ratios of xylem nuclei increased in G1, showed no significant change in S, but increased thereafter.

Cell Differentiation↗
PubMed1982

Nuclear changes accompanying cell differentiation in stems of Pisum sativum L.

Nuclear DNA, nuclear protein and nuclear size have been measured in cells of the cortex, pith and vascular tissue from three successive internodes in the stem of Pisum sativum. New techniques of computer-linked cytophotometry were used to measure these parameters simultaneously in both section and squash preparations. In cortical cells no endoreduplicated nuclei were seen in the internodes measured. In cortical cells from the oldest internode measured, a population of large nuclei with the 2C DNA amount was observed which was not present in the younger internodes. In the oldest pith nuclei measured a few 8C nuclei were present, but maturing pith was most characterized by increasing nuclear size and the population of nuclei accumulating with the 4C DNA amount. Polyploid nuclei were present in all of the vascular tissue measured, including the youngest internode. Maturing vascular tissue was also characterized by increasing nuclear size. Nuclear protein measurements demonstrated a close link between nuclear protein and nuclear size and suggest that increased nuclear size, with constant DNA content, may be due to increased nuclear protein. This raises the question of the nature and function of this nuclear protein, perhaps more characteristic of differentiating cells than dividing cells.

Cell Differentiation↗
PubMed1981

Combined staining procedures for cytophotometry of protein and DNA Feulgen-Naphthol Yellow S and dinitrofluorobenzene-Feulgen.

A comparison has been made between dinitrofluorobenzene (DNFB) and Naphthol Yellow S (NYS) as protein stains in combination with the pararosaniline-SO2 Feulgen procedure. Chicken erythrocytes were used as test cells. Cytophotometric measurements were made using a Zeiss scanning stage cytophotometer coupled to a PDP 11/10 minicomputer using the BICOSCAN program to obtain values for protein per cell, protein per "nuclear area' and DNA per nucleus. With 5N HCl as the Feulgen hydrolysis agent, DNFB staining, applied before the Feulgen procedure, was found to be unaffected by hydrolysis conditions required to give optimum Feulgen staining and showed only small losses after longer hydrolysis times. On the other hand measurements of NYS staining, of necessity applied after the Feulgen procedure, seem to be susceptible to the duration of Feulgen hydrolysis. This susceptibility is probably due to the interaction of the DNA phosphates with the basic amino acid residues, potential binding sites for NYS. Since the degree of this interaction may be variable, it is argued that NYS binding will measure the available basicity of proteins at the time of staining but no specific protein fraction. DNFB binding is unaffected by DNA-protein interactions and therefore can give a more reliable measure of "nuclear' protein, particularly in conjunction with Feulgen-DNA measurements.

Animals↗
PubMed1980

Protein staining methods in quantitative cytochemistry.

The chemical action and practical application of the Naphthol Yellow S, Alkaline Fast Green, Coomassie Brilliant Blue, Dinitrofluorobenzene and some lesser known protein staining methods have been surveyed with respect to their potentialities for quantitative cytochemical analyses. None of the dyes can be said to bind to any specific protein or group of proteins, but each may be used to analyse the presence of one or more particular amino acid residues. For the cytophotometric measurement of the 'total protein content' of individual cells and cell organelles the covalent binding Dinitrofluorobenzene and the electrostatic binding Naphthol Yellow S can properly be used. Fast Green FCF, applied at alkaline pH, binds electrostatically to the basic amino acid side chains of strongly basic proteins only but not in a quantitative (stoichiometrical) way. Coomassie Brilliant Blue, recently introduced to protein cytochemistry, may be useful for quantitative purposes. The combined Feulgen-Pararosaniline(SO2)/Naphthol Yellow S and Dinitrofluorobenzene/Feulgen-Pararosaniline(SO2) methods enable the simultaneous cytophotometric analysis at two different wavelengths for protein and DNA within the same microscopical preparation.

Animals↗
PubMed1979

Dual wavelength scanning cytophotometry (Bicoscan).

A computer program has been developed for stage-scanning cytophotometry of double-stained microscopical specimens. The program permits the simultaneous measurement of absorbance values at two wavelengths in each measuring spot. To account for overlap in the absorbance spectra of the two stained endproducts, the program incorporates correction of the measured data to compensate for the contribution of each chromophore to the absorbance measured for the other. The program will compute the corrected local absorbance values at specified wavelengths for each chromophore at each measuring spot and integrate these values over the total object to give separate totals for each stain. It is also possible to have integrated the absorbance values of one chromophore for all those measuring spots where the local corrected absorbance value of the other chromophore exceeds a preset minimum value. When this other chromophore is a nuclear DNA stain, it is possible to obtain an approximate measure of the content of any compound in the nuclear area which can be stained with a chromophore having an absorbance spectrum different from the DNA stain. The validity of the program was investigated on model preparations consisting of two (differently) coloured films of which the absorbance values could be measured either individually or in combination, by partially overlaying one film on the other. The program's potential has been demonstrated by using the combination of either Naphthol Yellow S or dinitrofluorobenzene as protein stains with the Feulgen-pararosaniline(SO2) procedure for DNA in chicken erythrocytes and rat liver cells.

Animals↗
PubMed1979

Hibitane bladder irrigation in the prevention of catheter-associated urinary infection.

The effect of regular chlorhexidine bladder irrigations on catheter-induced urinary infection in patients admitted as urological emergencies was investigated. Excluding patients infected on admission the urine remained sterile throughout the period of catheterisation in 52% of those receiving chlorhexidine but in only 26% of a control group of patients.

Aged↗
PubMed1979

The isolated circuit diathermy.

When using the conventional diathermy generator in surgery failure to apply the plate electrode can always present a serious risk of a thermoelectrical burn at any point where the patient makes contact with an earthed object on the operating table. The recent introduction of the earth-free (isolated circuit) diathermy should, under most conditions, provide complete protection against such risks. However, there are still certain circumstances under which even the isolated circuit may give rise to a thermoelectrical burn. Two such hypothetical examples are described; the sequences of events for these are fairly frequent occurrence.

Burns↗