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Biomedical subjects

D Kirk

Publications and source records attributed to D Kirk.

At least 91 records · Page 5Linked to original sources
PubMed1989

Two types of sheep Peyer's patches: location along gut does not influence involution.

In sheep, and some other species, there is evidence of two types of Peyer's patches (PPs), the ileal PP, which extends 150 cm along the terminal ileum, and the jejunal PPs distributed throughout the rest of the small intestine. The two types differ significantly in their histology, ontogeny and the extent of lymphocyte traffic. Another intriguing difference is that the ileal PP involutes about the time of puberty whereas the jejunal PPs function throughout life. This study shows that the differences in PP lifespan is not related to their specific location in the small intestine. Surgery was done at 1-2 months of age to transpose lengths of ileal PP into the jejunum, also, PP-containing lengths of jejunum were transposed into the midst of the ileal PP. Examination at age 12-16 months showed that ileal PP transposed into jejunum had involuted at the same rate as normally sited ileal PP. Also, jejunal PPs transposed into the ileum had not involuted unlike the surrounding ileal PP. It was concluded that the difference in lifespan of the two PPs were not related to the local microenvironment created by gut function, but may be inherent to the PP itself.

Aging↗
PubMed1988

Ketoconazole as primary treatment of prostatic cancer.

Ketoconazole 400 mg 8-hourly was used as primary hormonal treatment in 12 patients with advanced prostatic carcinoma. Four patients were withdrawn because of side effects and 1 died. The 7 patients who tolerated the drug had a reduction in testosterone and adrenal androgens. Six patients were fully evaluable. There was one partial response with complete remission of symptoms. Two patients enjoyed a subjective response and 3 showed no response. Ketoconazole had an effective biochemical action but the side effects seen in this study severely limit its usefulness. Ketoconazole has now been withdrawn as a treatment for prostatic cancer. However, less toxic derivatives might prove a useful addition to the drugs available to treat this condition.

Adrenal Cortex Hormones↗
PubMed1988

Progesterone assay by inhibition of reverse passive haemagglutination.

An assay for the steroid hormone progesterone is described based on the inhibition of the agglutination by progesterone-bovine serum albumin conjugate of red cells coupled with monoclonal antiprogesterone antibody (reverse passive haemagglutination). A low-affinity agglutination system produced the optimal sensitivity, capable of detecting less than 1 ng/ml steroid. This assay has the simplicity and sensitivity for a potential clinical test for placental or corpus luteum function. It also serves as a model for detection of other small ligands (drugs, hormones) by inhibition of reverse passive haemagglutination.

Animals↗
PubMed1988

Effects of low temperature on the respiratory metabolism of carbohydrates by plants.

The effects of lowering the temperature from 25 degrees C to 2-8 degrees C on carbohydrate metabolism by plant cells are considered. Particular emphasis is placed on the mechanism of cold-induced sweetening in tubers of potato (Solanum tuberosum). Temperatures between 0 and 10 degrees C were shown to cause a marked reduction in the rate of respiration of a wide range of plant tissues. At these temperatures the ability of suspension cultures of soybean (Glycine max), and callus cultures and tubers of potato to metabolize [14C]glucose was appreciably diminished. The detailed distribution of 14C showed that lowering the temperature decreased the proportion of the metabolized [14C]glucose that entered the respiratory pathways and increased the proportion converted to sucrose. Pulse and chase experiments, in which [14C]glucose was supplied to potato tubers at 2 and 25 degrees C, showed that lowering the temperature led to accumulation of label in hexose 6-phosphates, which were subsequently converted to sucrose. The patterns of 14CO2 production from specifically labelled [14C]glucose supplied to soybean suspension cultures and disks of potato tuber suggested that lowering the temperature reduced the activity of glycolysis more than that of the oxidative pentose phosphate pathway. It is argued that the above experiments demonstrate that lowering the temperature not only reduces the rate of carbohydrate metabolism but also alters the relative activities of the different pathways involved. A disproportionate reduction in glycolysis at the lower temperatures is suggested. Mature tubers of many varieties of potato accumulate sucrose and hexose when stored between 2 and 10 degrees C. Starch is the source of carbon for this synthesis of sugar. We could not detect cytosolic fructose-1,6-bisphosphatase in potato tubers and suggest that carbon for sugar synthesis in the cold leaves the amyloplast, not as triose phosphate, but probably as a six-carbon compound. Evidence is presented that phosphofructokinase (EC 2.7.1.11) plays a major role in regulating the entry of hexose 6-phosphates into glycolysis in potato tubers. Phosphofructokinase was purified from potato tubers and shown to consist of four forms. Three of these forms were shown to have higher Q10 values over the range 2-6 degrees C than over the range 12-16 degrees C and are regarded as being cold-labile. No such cold-lability was detected for the key enzymes involved in sucrose synthesis and the oxidative pentose phosphate pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1987

Idiotype-anti-idiotype interactions of VHIX-coded anti-progesterone and anti-arsonate antibodies. Comparison of passive haemagglutination and radioimmunoassays.

The reactivity and specificity of polyclonal and monoclonal anti-idiotypic antibodies raised against monoclonal anti-progesterone and anti-arsonate antibodies have been studied by solid phase radioimmunoassay (RIA) with immobilized idiotype and by passive haemagglutination with idiotype-coupled red cells. The sensitivity of the two methods was comparable, though some cross-reactions were only detected by RIA. Passive haemagglutination was found to be especially suitable in screening for monoclonal anti-idiotypes in hybridoma supernatants and ascites, and had advantages over RIA in detection of syngeneic anti-idiotypes. Demonstration of binding site-associated idiotopes was possible by haemagglutination inhibition. RIA and haemagglutination were used to investigate the idiotypic relationships between BALB/c antiprogesterone and anti-arsonate monoclonal antibodies which share heavy chains encoded by VHIX variable region genes.

Amino Acid Sequence↗
PubMed1986

What causes childhood leukaemia? Some beliefs of parents of affected children.

The theories of parents about the cause of their children's leukaemia have been documented in the course of a case-control study. From a sample of 175 children who were diagnosed as having acute lymphoblastic leukaemia, 91.4% of their parents put forward their theories. Some of these theories were related clearly to material that had been published and therefore had some scientific validity. Other theories often had no apparent scientific basis. Persons who are involved in the care of children with leukaemia should be aware of the wide variety of theories that are held by their parents so that they may provide counselling which could be of help in the relief of feelings of anxiety or guilt among the parents. Parents should always be afforded the opportunity to put forward their own theories so that they may be discussed on a rational basis. It is conceivable that some parents might put forward new hypotheses about leukaemogenesis that could be tested scientifically.

Attitude to Health↗
PubMed1986

Morphologically stable epithelial vesicles cultured from normal human endometrium in defined media.

Epithelium from normal human endometrium was cultured as morphologically stable vesicular structures in a defined, hormone-supplemented PFMR-4 medium. The structures consisted of a single layer of polarized epithelial cells with the apical surface facing the external culture medium, and the basal surface resting on a well-defined basal lamina adjacent to the internal lumen. Vesicles were shown to retain their viability for up to 3 mo. in culture, to actively synthesize DNA after being cultured for over a month in a defined medium, and to respond to steroid hormones. When embedded within a collagen gel, the vesicles reversed their epithelial polarity and formed branching, pseudoglandular structures. It was concluded that the three-dimensional shape of the epithelial vesicles had a critical role to play in their morphological stability, nutrient requirement, and hormone sensitivity.

Adult↗
PubMed1986

Comparison of silicone and latex catheters in the development of urethral stricture after cardiac surgery.

In an earlier series of 100 men followed up for between 3 and 12 months after coronary artery bypass grafting, the incidence of urethral stricture was 2%. These patients have now been followed up for between 15 and 24 months and the incidence of urethral stricture has risen to 5.2%. Latex catheters were used in these patients. A separate group of 117 men underwent coronary artery bypass grafting and were catheterised with silicone catheters. They were followed up for between 12 and 28 months and no urethral strictures were found. It is recommended that silicone catheters be used routinely for short-term catheterisation in men undergoing cardiac bypass surgery.

Coronary Artery Bypass↗
PubMed1985

Delayed methylation and the matrix bound DNA methylase.

It is shown that the methylation of DNA that occurs in isolated nuclei is "delayed methylation". This methylation is not reduced in nuclei which have been pretreated with 0.2M NaCl to extract the soluble methylase suggesting that this methylation is the product of a firmly bound matrix associated DNA methylase. Evidence is provided that, like the methylase, the DNA substrate is associated with the nuclear matrix.

Animals↗
PubMed1985

Selective growth of normal adult human urothelial cells in serum-free medium.

A serum-free medium (HMRI-2) has been developed for the outgrowth and subculture of epithelial cells from normal adult human ureter and bladder. Medium HMRI-2 consists of Ham's MCDB 152 with double the amounts of the essential amino acids in Stock 1, low Ca2+ (0.06 mM) and is supplemented with epithelial growth factor, 5 ng/ml; transferrin, 5 micrograms/ml; insulin, 5 micrograms/ml; ethanolamine and phosphoethanolamine, 0.1 mM each; hydrocortisone, 2.8 X 10(-6) M; and bovine pituitary extract, 126 micrograms protein/ml. The cultured cells showed ultrastructural markers of epithelial cells (prekeratin fibers, tonofilaments, surface microvilli with glycocalyx), exhibited ABO antigens, and had a normal human diploid karyotype. Primary cultures could be subcultured and also cryopreserved in HMRI-2 in liquid nitrogen. Cells in mass cultures showed a population doubling time of 40.5 +/- 4.5 h and had a maximum in vitro life span of 20 to 25 population doublings. It was observed that primary outgrowths, secondary cultures, and even cryopreserved cells all retained the capacity to respond to high Ca2+ and serum by differentiation and desquamation. This study has resulted in the availability of easily obtainable serum-free epithelial cultures from normal adult human ureter and bladder. The useful in vitro life span of these cultures may be important in future studies of carcinogenesis.

Adolescent↗
PubMed1985

Novel antigen system for tracking epithelial cell migration in serum-free culture.

We report here a unique system for tracking normal human urothelial cell migration in serum-free culture medium (HMRI-1). The key observation was that urothelial cells deposited red blood cell surface antigen on the culture dish in a remarkable pattern. Scrutiny of this pattern showed that each migrating cell left behind antigen imprints which formed parallel tracks the width of the cell. Hence the previous migratory history of the cells was instantly mapped by simply visualizing the antigen tracks deposited by the cells on the dish. Apart from providing a simple method for tracking urothelial cells, this observation has wider implications for mechanistic studies of epithelial cell movement in general. It also highlights the complicating effects associated with the addition of serum as a traditional culture supplement, since the inclusion of serum in the HMRI-1 medium abolished the above effect by inhibiting cell migration.

ABO Blood-Group System↗
PubMed1985

Growth of a malignant human urothelial cell line (J82) in a serum-free medium (HMRI-1) developed previously for normal human urothelium.

A malignant human urothelial cell line (J82) has been cultured in a serum-free medium (HMRI-1) developed specifically for normal human urothelium. Unlike the normal human urothelium which grew as an attached monolayer, the J82 cells proliferated as free floating cellular aggregates. Comparative growth kinetic studies have shown that the J82 cells, unlike normal cultured urothelial cells, did not require epidermal growth factor, bovine pituitary extract or transferrin as single additives in the HMRI-1. However, deletion of certain combinations of these factors markedly reduced growth. It was concluded that the J82 cells had a reduced dependency on the normal urothelial cell growth factors suggesting that the J82 cells had altered nutritional requirements which might possibly be associated with the production of autocrine growth factors.

Carcinoma, Transitional Cell↗