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Biomedical subjects

R Victor

Publications and source records attributed to R Victor.

At least 19 recordsLinked to original sources
PubMed2004

Evaluation of the mercury exposure of dental amalgam patients by the Mercury Triple Test.

AIMS: To establish and analyse reference data for the mercury burden of patients with and without amalgam fillings. METHODS: Atomic absorption spectroscopy was used to quantify Hg concentrations in the scalp hair and urine (before and after application of dimercaptopropane sulphonate), and Hg release from dental amalgams (using a newly developed, amalgam specific chew test), in 2223 subjects. RESULTS: 50th centiles were 1.3 microg Hg/g creatinine in basal urine, 32 microg Hg/g creatinine after DMPS application, 454 ng Hg/g in hair, and 27 microg Hg per g of chewing gum, which corresponds to about 1 micro g Hg released per minute of chewing. Total Hg intake (from ambient air, drinking water, food, and amalgams) of most patients is well below the provisioned tolerable weekly intake (PTWI) defined by the WHO, unless extremely Hg rich food is consumed on a regular basis. However, for patients exceeding the 75th centile in chew tests, total Hg intake exceeds the PTWI by about 50%, even at the low limit of intake from food. In the absence of occupational exposure, significant Hg release from dental amalgams is a necessary but insufficient condition to obtain a high long term body burden. After removal of dental amalgams, chew tests no longer exhibit oral Hg exposure, while basal urine Hg content and DMPS induced excretion display a exponential decrease (half life about 2 months in both cases). CONCLUSIONS: A standardised procedure for evaluation of the magnitude and origin of the Hg burden of individuals has been developed, which, by comparison with the database presented here for the first time, can serve as a diagnostic tool.

Body Burden↗
PubMed2004

A modified thionin acridine-orange stain for mast cells.

For in vitro studies in mesentery, toluidine blue and thionin dyes are generally used. We have tried thionin and acridine orange stains and found it to be good as it showed good colour contrast between mast cells and the background tissue. The two dyes were selected to give good colour contrast.

Acridine Orange↗
PubMed1999

Human breast-cancer metastasis formation in a nude-mouse model: studies of hyaluronidase, hyaluronan and hyaluronan-binding sites in metastatic cells.

Few animal models are available to study metastasis formation. The purpose of the present study was to obtain a useful model of metastasis formation in nude mice in an attempt to analyze the stroma reaction and in particular the production and the expression of hyaluronan (HA), hyaluronidase, and HA-binding sites by cultivated cells, and HA and hyaluronectin (HN) in the invasive areas of tumors. Nude mice were subjected to i.p. injections of several human cancer cell lines (PLC/PRF/5, HepG2, CB 191, CB 193, PC3, CAL 51, SA 87 and SA 98), and formation of metastases was analyzed in different organs (lung, liver, kidney, spleen and axillary nodes) by immunohistochemical techniques. CAL 51, a breast-cancer-metastasis-derived cell line with a normal karyotype, produced i.p. tumors in 75% animals and metastases in 90% animals (detected in the liver and axillary nodes). Two modes of invasion by CAL 51 cells were observed in the liver: one, direct, from the surface of the liver and the other, indirect, via the bloodstream. HA and HN were strongly expressed at the invasion areas. A cell line derived from hepatic metastasis of CAL 51 (HMD CAL 51) presented an abnormal karyotype. HMD CAL 51 produced more hyaluronidase (12-fold) and HA (10-fold) and expressed more CD44 (1.6-fold) and other HA-binding sites (9.5-fold) than the established cell line CAL 51. Our results show that i.p. injection of the CAL 51 cell line into nude mice provides a useful model of metastasis formation. The passage of the CAL 51 cells from the primary state to the metastatic state was characterized by a dramatic increase of HA and hyaluronidase production, and expression of HA, HN and HA-binding sites.

Animals↗
PubMed1999

Activation and inhibition of human cancer cell hyaluronidase by proteins.

Results regarding hyaluronidase activity in tumor extracts or cell lines are subject to variations according to the method used for the assay and, sometimes, within an assay. Hyaluronidase was assayed at pH 3.8 in the culture medium of the human cancer-derived cell lines SA87 and H460M by several techniques: HPLC, Reissig technique, ELSA technique, and zymographic analysis. The optimal pH was between 3.3 and 4 in solutions at constant 150 mM sodium concentration. The enzyme was reversibly inhibited by sodium concentration over 200 mM. The activity of purified hyaluronidase increased in the presence of low concentrations of the specific HA-binding glycoprotein hyaluronectin, or of bovine serum albumin or immunoglobulins, or of human albumin, transferrin, or hemoglobin, showing that proteins cooperate in enzyme activity. The ELSA technique showed that optimal pH was slightly lower in the presence of HN than that with BSA. The optimal BSA concentration was determined with the ELSA technique at 0.1 g/liter, and excess of either protein inhibited hyaluronidase. When measured with the Reissig technique, the activity of purified enzyme in the presence of 0.1 g/liter BSA was up to fourfold that without BSA. The cooperative effect of BSA was visualized by zymography. We conclude that the total protein content of hyaluronidase solutions must be considered to correctly interpret quantitation of the enzyme in sera or tissue extracts because protein concentrations above 200 microg/liter lead to underestimation of the enzyme.

Animals↗
PubMed1999

Carabid beetle invasion of the ear in Oman.

Two cases of human ear invasion by a predaceous beetle, Crasydactylus punctatus Guerin (Coleoptera; Carabidae), are reported from the Sultanate of Oman. The first case was that of a 35-year old woman who suffered a severe otologic injury caused by the biting and chewing of the external auditory canal and the tympanic membrane. The beetle then entered the middle ear and caused sensorineural hearing loss. The second case involved a 22-year-old male from whose ear a specimen of the same species was successfully removed after it was immobilized with 10% lidocaine spray. These cases are presented with discussion.

Adult↗
PubMed1998

Ophthalmomyiasis in Oman: a case report and comments.

A case of external ophthalmomyiasis caused by the first instar larvae of the sheep nasal botfly (Oestrus ovis) has been reported for the first time from the Sultanate of Oman, Southern Arabia. Sixty larvae were removed from the left eye of a 21-year-old male student, who acquired the infection during a field trip. The manual removal of larvae using a swab stick was the only effective treatment. The larval characteristics are described with illustrations, and the status of O ovis ophthalmomyiasis in the Middle East is discussed. The folk treatment administered for fly-mediated ophthalmomyiasis in Oman is also reported. Ophthalmomyiasis may not be a serious public health problem in Oman, but a nationwide survey of all myiases may be worthwhile.

Adult↗
PubMed1997

[Production of hyaluronidase by cultured human tumor cells].

The presence of hyaluronidase was detected at pH 3.8 in eight out of twelve human cancer cell line culture media. Eight cell lines derived from primary tumours and four from metastases. In three culture media the enzymatic activity was lower than 0.035 pU/cell/h. In five others (in a hepatoma cell line and in four metastasis-derived cell lines) the activity was higher than 0.057 pU/cell/h. A tumour-derived fibroblast culture was negative. The optimal activity was observed at a pH comprised between 3.6 and 4. Salt inhibition of hyaluronidase was reversible. The enzyme was denaturated by a 10-min heating at 70 degrees C. The enzyme was not strictly specific for hyaluronan hydrolysis but also digested chondroitin sulfates. PH20, a spermatozoid protein that has homologies with the bee venom hyaluronidase, was not expressed by cell lines tested.

Chromatography, High Pressure Liquid↗
PubMed1989

The effects of road and bridge construction on the bank-root macrobenthic invertebrates of a Southern Nigerian stream.

A comparative study was conducted at three stations on a fourth order Nigerian stream to evaluate the effects of a road and bridge construction on the macrobenthic invertebrates of the bank-root biotope. Siltation and sedimentation appear to be the important factors affecting macroinvertebrates. At station 2, the construction site, there was a considerable reduction in the occurrence and abundance of invertebrate taxa; different groups of invertebrates showed varying responses to perturbational stress; the taxa richness, general diversity and evenness were also low. Irregular fluctuations in diversity and evenness suggested that the benthic community of station 2 was less stable than those of upstream and downstream stations. The concentrated dominance of Ephemeroptera and Coleoptera at station 2, despite low diversity, reflected the ability of a few tolerant taxa to occur there in high abundance. Faunal comparisons of the three stations confirmed the perturbational stress caused by construction activities.

Journal Article↗
PubMed1989

Anticomplementary activity and the safety of intravenous immunoglobulin.

Quality assurance release levels for anti-complementary (AC) activity of a non-modified intravenous immunoglobulin (IGIV, pH 4.25) were reviewed over a period of one year and nine months in an attempt to correlate the incidence of complement-mediated-type adverse reactions with the AC level. Over 200 lots and ten possible complement-mediated side effects were evaluated. No correlation was found. A similar evaluation was made of a prospective study in which three lots of IGIV, pH 4.25 (one with a low, one with a mid-range, and one with a high AC activity) were used; again no correlation was found. Finally, a comparison was made between the AC activity assay used to release IGIV, pH 4.25 and an alternative AC activity assay designed for a highly modified IGIV preparation. It was demonstrated that the AC activity assay designed for the modified preparation and its assay limits were unsuitable in attempting to define AC activity of the nonmodified preparation.

Complement Inactivator Proteins↗
PubMed1979

Thermonuclease seroinhibition test for distinguishing Staphylococcus aureus from other coagulase-positive staphylococci.

Since coagulase-positive staphylococci from animals are heterogeneous, another test is necessary to distinguish Staphylococcus aureus from them. Staphylococcal thermonucleases appear to be heterogeneous; antisera raised against S. aureus isolated from humans inhibit thermonuclease activity as demonstrated by the metachromatic well-agar diffusion method. The serological specificity of the thermonuclease elaborated by S. aureus of human origin was demonstrated using three antisera and 407 strains of staphylococci from diverse human and animal sources.

Animals↗
PubMed1978

Effects of biofeedback and voluntary control procedures on heart rate and perception of pain during the cold pressor test.

The effects of biofeedback training and voluntary control procedures on heart rate and subjective reactions to 30-sec immersion of the hand in ice water were investigated in five experimental conditions, nine subjects in each condition. All subjects were given an initial cold pressor test and a final test interspersed by the particular condition. In two of the conditions, subjects were given biofeedback training for increasing or for decreasing heart rate. No training was given to the other three groups. In two of the latter conditions, subjects were simply asked to increase or decrease their heart rate during the second cold pressor test, without previous training. The fifth condition was a no-treatment habituation control. Significant variations between groups were obtained of the tachycardia and reports of pain associated with the second cold pressor test. In general, there was a correspondence between heart rate change and subjective report of pain. Voluntary control of heart rate or other autonomically-mediated responses, enhanced by biofeedback training, may have implications for research on and clinical management of physiological and subjective reactions to stressful stimuli.

Adolescent↗
PubMed1975

Glycosaminoglycans from Ateroid and bovine duodenal mucosa and pancreas.

Glycosaminoglycans (GG) were isolated from commercial Ateroid and compared with those from bovine duodenal mucosa and pancreas. The major GG in Ateroid is heparin. Heparan sulfate (HS) and dermatan sulfate were also found. HS, chondroitin sulfates, and heparin were isolated from duodenal mucosa after papain digestion, but a residue, non-digestible, was mostly heparin. Pancreas contains very little GG, and the GG composition is similar to that of mucosa. The heparin isolated from Ateroid and mucosa have similar lipoprotein lipase-releasing activity, but the former has considerably less anticoagulant activity. Interestingly, papain digestion of mucosa and pancreas did not release all heparin from the tissue, suggesting that the protein to which heparin is linked is not readily accessible to the enzyme.

Animals↗