Biomedical subjects

D J Gee

Publications and source records attributed to D J Gee.

At least 19 recordsLinked to original sources

PubMed1991

Urine hydroxyproline: a potential error in quantification and a proposed procedure for its measurement.

A modification of the colorimetric method of Bergman and Loxley for the measurement of urinary hydroxyproline using external aqueous hydroxyproline standards instead of individual internal standards is described. We show that this modification leads to an underestimation (average 32%) of hydroxyproline because suppression of colour development occurs in urine samples but not in aqueous standards. Use of an internal standard for each urine test corrects for this suppression. Recovery of hydroxyproline (250 mumol/L) added to 12 patient urine samples averaged 99% and the overall imprecision for the assay was then less than 5%. Modifications to the original hydrolysis and colour development procedures allow linearity to 1500 mumol/L. Details of our procedure are given.

Colorimetry↗

PubMed1989

Study on the effects of heat on blood and on the post-mortem estimation of carboxyhaemoglobin and methaemoglobin.

Blood samples of different carboxyhaemoglobin (CoHb) content (0%, 50%, 100%) were analysed, after short exposure to heat, for determination of the change of CoHb and methaemoglobin (MetHb) during the succeeding 14 days. Untreated blood showed an initial increase of MetHb after heating followed by a decrease during this period. There was no formation of CoHb in the untreated blood. When CoHb was already present in the blood the amount of MetHb was smaller in amount and was formed at a slower rate. In these samples the concentration of CoHb slowly decreased.

Burns↗

PubMed1988

Simple laboratory experiments to replicate some of the stresses on vertebro-basilar arterial walls. An investigation of possible mechanisms of traumatic subarachnoid haemorrhage.

The hypothesis that reversed blood flow in transiently occluded vertebral arteries may be responsible for some cases of massive traumatic subarachnoid haemorrhage has been investigated in vitro. Simple laboratory tests were performed on 25 vertebro-basilar arterial systems, and succeeded in producing either longitudinal tears in normally structured vertebral arteries, or tears at the origin of the posterior inferior cerebellar arteries. The results indicated that under such conditions, with systolic blood pressure in the physiological range, reversed blood flow had different characteristics and stressed the arterial wall to the point where it yielded.

Adult↗

PubMed1987

The toxic plant proteins ricin and abrin induce apoptotic changes in mammalian lymphoid tissues and intestine.

The toxins ricin and abrin are potent inhibitors of protein synthesis. Apoptosis has been shown to be induced in some cells by cycloheximide and actinomycin D whereas the process is prevented in other cells by the same agents, both inhibitors of protein synthesis. We were interested to find whether ricin and abrin caused any apoptotic changes in rapidly dividing tissues where we believed that these toxins concentrate. Rats were injected intramuscularly with toxin and killed at time intervals, tissues being removed and examined by light and electron microscopy. Apoptotic-like bodies were abundant in para-aortic lymph nodes, Peyer's patches and ideal crypts of ricin or abrin intoxicated rats. Abrin was found to cause markedly more pronounced changes in these tissues, when compared with a similar dose of ricin. Prior to this, these toxins have been reported as causing necrosis in animal tissues.

Abrin↗

PubMed1986

Immunocytochemical detection of ricin. II. Further studies using the immunoperoxidase method.

Radio-iodinated ricin was injected into rat muscle in vivo to establish the distribution of the toxin at various time intervals after injection. Injection site muscle and para-aortic lymph nodes were selected for localization of ricin by the immunoperoxidase technique. Sections of snap-frozen tissues were fixed using a variety of methods to establish the best protocol for the immunodetection method. This was found to be with an ether-ethanol mixture. Ricin was detected in tissue at the site of injection taken from rats sacrificed 1, 4, 8 and 24 h after injection and in tissue from animals dying from ricin intoxication after about 30 h. This method, however, failed to demonstrate unequivocally the presence of ricin in lymphoid tissue which had been indicated by the radiotracer study. The significance of these findings and their relevance to forensic diagnosis are discussed.

Immunoenzyme Techniques↗

PubMed1985

Renal tubular epithelia ultrastructure in autolysis.

Post-mortem changes in the proximal and distal tubules of rat kidneys left in situ have been studied at the light microscope and ultrastructural levels. The distal tubular nuclei showed distinct changes which were completely different from the usual nuclear appearances after death and resemble the changes seen in apoptosis. These observations suggest that the unusual changes in the autolytic distal tubular nuclei may be due to the activation of endogenous endonucleases.

Animals↗

PubMed1985

The use of fluorescence microscopy and microfluorimetry to study the distribution of quinacrine in mice.

A simple method was used to prepare cryostat-cut sections in which quinacrine-induced fluorescence could be seen by fluorescence microscopy. Such sections were used in preliminary studies of the distribution of this drug in mice. Micro-fluorimetry was used to quantify the fluorescence. The method may be of value in the detection of drugs in various fields.

Animals↗

PubMed1985

Immunocytochemical detection of ricin. I. Preliminary immunofluorescence studies.

Ricin injected into rat muscle in vivo can be localized within a few hours using routine immunofluorescence techniques on formalin-fixed tissues. However, the level of sensitivity decreases with increase in size of animal injected, time after administration and decrease in dose given. These findings are discussed in relation to the known chemistry and subcellular mode of action of ricin.

Animals↗

PubMed1984

Novel application of aniline blue. Fluorescent staining of glycogen and some protein structures.

The present study shows that aniline blue can be used as a fluorescent stain for glycogen. The dye is also helpful in tracing pathological and autolytic changes in lysosomes, mitochondria, erythrocytes and nuclei, and it can also be used for demonstrating bacteria in tissue sections and smears. The techniques used are simple, rapid and inexpensive. Spectrophotometric studies on aniline blue solutions have shown that aniline blue fluorescence was enhanced by the addition of certain proteins, or of glycogen to the dye solution. In case of albumen which has the maximum effect, enhancement is dependent upon the albumen-dye ratio. The mechanism of staining is mainly due to self quenching, but there is also an evidence of the presence of hydrophobic reaction.

Aniline Compounds↗

PubMed1984