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Biomedical subjects

D K Whittaker

Publications and source records attributed to D K Whittaker.

At least 73 records · Page 4Linked to original sources
PubMed1975

Ultrastructural changes in muscle following freezing in situ by a surface applied cold probe.

Freezing of tissues under the conditions of cryosurgery resulted in changes in the muscles shortly after thawing occurred. The changes were progressive and included dilatation of mitochondria and sarcoplasmic reticulum, loss of glycogen, disruption of myofilaments and pyknotic changes in the nuclei. The progression of events is similar to other diseases of muscle but is structurally and chronologically unique. It does not appear to be typical of the early stages of ischaemia of muscle. It is suggested that the rapid onset of fibre damage following thawing is consistent with progressive alterations caused by ice-crystals at the time of freezing.

Animals↗
PubMed1975

Some laboratory studies on the accuracy of bite mark comparison.

Bite marks in wax and in pig skin were compared with study models of the subject making the bite. Photographs, impressions and measurements of the bites were used. Bites in wax could be readily identified especially if measurements were made on photographs but identification from bites in non-vital pig skin was more unreliable. It is suggested that similar difficulties may be encountered in the assessment of bites in human skin. Expert witnesses involved in presenting evidence on bite marks in a court of law should be aware of the difficulties of making valid comparisons even under standardized laboratory conditions. Further studies to improve and substantiate the reliability of the technique are clearly required.

Adult↗
PubMed1971

Microstructure of colonies of rod-shaped bacteria.

Whole colonies of Bacillus cereus, B. megaterium, B. mycoides CN2495, Corynebacterium hofmanni NCTC1938, Escherichia coli, Lactobacillus acidophilus NCIB1899, Nocardia graminis NCTC4728, Pseudomonas viscosa, and Serratia marcescens were prepared for scanning electron microscopic examination by freeze-drying and metal-coating. The arrangement of individual cells within colonies could be seen. Cells of Bacillus colonies tended to be longer than in liquid culture and irregular in shape and to give the appearance of branching. B. megaterium colonies frequently had a dense covering film. Colonies of gram-negative bacteria consisted of fairly short rods covered by much adherent extracellular material. L. acidophilus had colonies comprised of densely packed, well-oriented rods. C. hofmanni colonies contained coccobacilli, packed together. Correlations were observed between plano-convex colony form and densely packed cells, rough colony form and random arrangement of well-separated microorganisms, and irregular colony edge and tendency of cells to grow out from the colony in filaments.

Aerobiosis↗
PubMed1970

Scanning electron microscopy of intact colonies of microorganisms.

Colonies of S. mutans OMZ61, Streptococcus sp. D182, Staphylococcus aureus Oxford NCTC 6571, and Candida albicans type A, MRL 3153 were grown on various media. Cubes of agar bearing two to three colonies were excised and processed for scanning electron microscopy. The characteristic shape of the colonies was seen when examined at low magnifications. At a magnification of 2,000 diameters, the arrangement of individual organisms within the colonies was observed. Plano-convex colonies consisted of uniformly distributed organisms, whereas S. mutans colonies presented a more complex arrangement possibly associated with the production of extracellular polysaccharides. Certain colonies were totally or partially covered by an adherent film through which the outline of the organisms could be distinguished.

Candida↗