Biomedical subjects
Publications and source records attributed to S S Cross.
It is suggested that mitosis arose in evolution as a mechanism for 'excreting' damaged DNA (mutations). The mechanism for excretion involved replication of the DNA and was thus a pre-adaptation that could be used for cell replication. In multicellular organisms the mutated cells cannot always be lost and may persist as neoplasms.
Two brominated tyrosine metabolites, fistularin 3 [1] and a new compound 11-ketofistularin 3 [2] have been isolated from a marine sponge, Aplysina archeri. Their structures were determined on the basis of spectral data. Both compounds inhibited the growth of feline leukemia virus.
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The diffusion of fixatives is slow. Early work using plasma gels and animal tissues showed the distance penetrated by a fixative to be a simple function of the fixation time but this relation has not been established in human tissues. The rates of diffusion into whole human spleens were measured for three primary fixatives over periods ranging from one to 25 days. A positive correlation was demonstrated between penetration distance (mm) and fixation time (hours). The diffusion rates were slower than those in previous studies. These results have possible implications for the handling of surgical specimens.
Histopathology reports on 20 mastectomy and 20 colectomy specimens containing carcinomas were examined from the beginning of each decade for the period 1940-1990. The number of words and items of information in each report were recorded. There was a large (337%) increase in the number of words in reports of both types of specimens with a slightly smaller increase (273%) in the number of items of information. This increase may be due to clinician-led demand for more specific information or be related to the introduction of more detailed systems of pathological staging and prognostic assessment of breast and colonic tumours. The increase in data production and dissemination may not be reflected in workload measurement systems, such as Welcan, and must be considered when assessing the need for secretarial staff.
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The quality of specimen fixation was examined within a routine diagnostic histopathology service. For each specimen the adequacy of fixation was assessed and the transit time between operating theatre and the laboratory was measured. Preliminary fixation was found to be inadequate in 25% of specimens and some form of manipulation to assist fixation was required in 36% of specimens. The mean transit time was 22 (SD 10.7) hours. Specimen fixation and transport are additional factors to consider in quality assurance of histopathology.
The numbers of papers published between 1966 and 1990 which could be of relevance to a histopathologist were assessed. The search for papers was conducted under 18 medical subject headings using the CD-Plus Medline computerised database for the years 1966, 1978, 1982, 1986 and 1990. Between 1966 and 1990 16 categories showed an increase in the number of indexed papers and in 11 of these the increase was by over 200%. The two categories that showed a slight reduction were cytodiagnosis and polarisation microscopy. The total number of papers of probable relevance to histopathology in 1990 was 36,780, a 293% increase since 1966; this increase was greater than the increase in the total number of papers indexed (189%). The number of papers relevant to histopathology has increased dramatically in recent years and this increase has been proportionately greater than in some other areas of medicine.
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The effect of delay in fixation on the modified Bloom and Richardson grade of eight breast carcinomas was investigated. Topologically shuffled samples of each tumour were immersed in fixative at times of 0.5, 2, 4, 6, 18 and 24 h after surgical removal. The grade of each tumour was assessed at delays of 0.5 and 6 h. The tubule formation and nuclear pleomorphism components of the grade showed no change with a delay in fixation of 6 h. The number of mitotic figures declined by a mean of 53% over the same period and this resulted in a decrease in the histological grade of one of the tumours. The implications of these findings for the handling of breast specimens in a diagnostic histopathological laboratory are discussed.
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Histological sections of spleen and both kidneys from 372 necropsies were examined for the presence of cholesterol emboli. These were identified in nine (2.4%) cases and the clinical histories of these cases were reviewed. All the subjects with cholesterol emboli were older than 60 years and eight out of nine were male. Lesions of differing ages were found in individual cases, suggesting that the process of embolism was recurrent. Two of the cases had undergone arteriography procedures in the month before death and, if these were excluded, then the incidence of "spontaneous" cholesterol embolism was 1.9%. This incidence is much lower than that of previously published studies and may be due to a lower incidence of cholesterol embolism in Britain compared with North America or a decrease in incidence over the past two decades. In three of the subjects with cholesterol embolism the cause of death could be related to systemic atherosclerosis, but in the other six cases there was no apparent correlation between the finding of cholesterol embolism and the cause of death. The clinical relevance of the histological finding of cholesterol embolism can only be assessed in conjunction with clinical information.
One hundred necropsies were performed by four junior pathologists wearing safety spectacles. The number of blood splashes on the spectacle surfaces were counted after each necropsy. Splashes were found after 22 necropsies (range 10-34%), with higher numbers being seen among the more junior grades of pathologist. This suggests that the use of safety spectacles should be considered by all pathologists performing necropsies.
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The effect of delay in fixation on the number of mitotic figures in tissues has received little attention, and previous studies have reached differing conclusions. The numbers of mitotic figures in the normal mucosa of six colectomy specimens were counted with delays in fixation of 30 minutes, one hour, two hours, three hours and six hours for samples from each specimen. The numbers of mitotic figures were counted in 50 whole crypts in each specimen by two observers. All phases of mitosis were counted. The number of observable mitotic figures declined by about 30% with a delay in fixation of two hours and by 50% with a delay of six hours. This observation has important implications for the handling of surgical specimens.