Biomedical subjects
Publications and source records attributed to S Nordling.
Charged polymers, known to alter cell surface characteristics, reversibly inhibit the intercellular communication required in kidney tubule induction. This effect seems to be a function of their charge density. It is suggested that this effect is due to the formation of a molecular barrier between the interacting cell surfaces.
The induction of kidney tubules in metanephric mesenchyme has previously been shown to require close contact between the interacting tissues. In our study we show that low concentrations of inhibitors of RNA, DNA and protein synthesis inhibit tubule induction, although they do not seem to prevent the formation of contacts between the interacting tissues. The effective concentrations were about the same as those which inhibited the synthesis of macromolecules. Cycloheximide caused an increased synthesis of RNA. Low concentrations of Mitomycin C inhibited DNA synthesis but not tubule formation. A concentration of the inhibitors which caused weakened induction also caused a marked decrease in leucine incorporation. We concluded therefore, that a decrease in protein synthesis in the inducing tissue is responsible for the inhibition of induction.
The human En(a-) blood group is a rare recessive trait. These erythrocytes lack the major membrane sialoglycoprotein (PAS1, MN protein, or glycophorin) and contain a decreased amount of PAS2 as demonstrated by radiolabeling of surface porteins and chemical techniques. A third glycoprotein, Band 3, contains two labeled oligosaccharide chains; the more complex oligosaccharide has a higher molecular weight in En(1-) cells than in normal cells. A fourth glycoprotein, PAS3, is present in usual amounts in En(a-) cells. Cells heterozygous for En(a) are intermediate in these respects. The sialic acid is decreased in En(a-) cells, but the total carbohydrate is similar in the different membranes. The glycolipids are present in normal amounts but are much more exposed to galactose oxidase in En(a-) cells than in normal cells.
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Five cases with multiple jaw cysts from two families, and two other unrelated patients are presented. Multiple keratocysts of the jaws were found in all patinets whose cysts had been examined histologically. There were also several follicular cysts without keratinization. In some cysts there was even a pronounced proliferation of the basal cells, which resembled basal cell carcinoma. Basal cell carcinomas were seen in only three patients, apparently because the series had been selected for the presence of multiple jaw cysts. However, two patients with only pigmented nevi showed a marked proliferation of the basal cells. An elevation of serum alkaline phosphatase was noted in four out of five patients. The sella turcica was bridged in all but one patient and fusion of the vertebrae was seen in all but two patients. In addition, a high frequency of rib anomalies, frontal and parietal bossing, mild mandibular prognathism and dural calcification was seen. Therefore, what is called the basal cell nevus syndrome may be regarded as a skeletal dystrophy syndrome. Based on the family pedigrees, an autosomal dominant inheritance with poor penetration seems probable.
Guinea pig lymph node and blood lymphocytes have been physically fractionated in preparative cell electrophoresis into two functionally viable populations, the high mobility cell population (HMC) and the low mobility cell population (LMC). By using cell surface markers and functional tests known to be specific for T and B lymphocytes, respectively, it is shown that the T lymphocytes localize in the HMC population and the B lymphocytes in the LMC population. The spleen lymphocytes do not separate into the two populations. They move into one single broad peak containing both T and B cells. This finding indicates the presence of electrokinetically different subsets of T and B lymphocytes in the spleen on one hand and in the lymph node and blood on the other hand.
The presence of cytoplasmic material inside thin Millipore filters between interacting mouse metanephric mesenchyme and spinal cord was investigated using different fixation methods. The transmission of induction was studied from sections of Zenker-fixed paraffin-embedded explants. Formation of kidney tubules was taken as evidence for induction. Filters with 0.8 and 0.22 mum pores permitted induction, whereas only 6 out of 31 filters with 0.1 mum pores did so. Glutaraldehyde-fixed Epon-embedded explants were used for study of cytoplasmic penetration into filters. In thick sections, filters with large pores were seen to contain cytoplasmic material at all levels. Filters with 0.1 mum pores usually showed only shallow ingrowth, but those which had permitted passage of induction contained material at least half way from the spinal cord and shallow ingrowth from the mesenchyme. With 0.8 mum filters the ingrowths from both sides met first after 18 h of transfilter cultivation. This has previously been shown to be the minimum time needed for induction to take place in this system. In electron microscopy cytoplasmic processes were seen deep inside the 0.8 and 0.22 mum filters regularly permitting induction. In small pores such material was only preserved by certain glutaraldehyde fixatives. Diffusion studies did not reveal major differences between induction-permitting 0.22 mum filters and induction-preventing 0.1 mum filters. Thus in the kidney tubule induction system this and our previous work speak in favor of a mechanism based on close apposition of cells rather than on long-range diffusion of inductive substances or on matrix interaction.
The correlation between the histopathological diagnosis of biopsies from colorectal villous tumours and that of the excised tumour (in 16 cases of carcinoma only clinical diagnosis, autopsy or death certificate) was investigated. In the persent retrospective study 235 biopsies were taken from 134 tumours where the final diagnosis had been established. In the benign groups the grade of the biopsy was the same as that of the surgically excised tumour in about 50%. However, 25% of the biopsies with a benign diagnosis were in fact taken from carcinomas. Not even multiple biopsies exclude the presence of cancer in a villous papilloma. The tumour should be totally excised and histologically examined.
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Electrophoretically fractionated CBA/Ca spleen T cells alone respond to allogeneic cells in one-way MLC and to PHA. They do not respond to E. coli LPS. B cells alone do not respond to allogeneic cells nor to PHA, but do respond to LPS. When karyotypically distinguishable syngeneic mixtures of T and B lymphocytes are stimulated with allogeneic cells, at the most 5% of mitoses on 5-9th culture day are of B cell origin. This indicates that B cells are not substantially recruited to proliferate in the MLC.
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