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Biomedical subjects

D Blair

Publications and source records attributed to D Blair.

At least 19 recordsLinked to original sources
PubMed1992

Genetic variants within the genus Echinococcus identified by mitochondrial DNA sequencing.

The pattern of species and strain variation within the genus Echinococcus is complex and controversial. In an attempt to characterise objectively the various species and strains, the sequence of a region of the mitochondrial cytochrome c oxidase subunit I (CO1) gene was determined for 56 Echinococcus isolates. Eleven different genotypes were detected, including 7 within Echinococcus granulosus, and these were used to categorise the isolates. The 4 generally accepted Echinococcus species were clearly distinguishable using this approach. In addition, the consensus view of the strain pattern within E. granulosus, based on a variety of criteria of differentiation, was broadly upheld. Very little variation was detected within Echinococcus multilocularis. Remarkable intra-strain homogeneity was found at the DNA sequence level. This region of the rapidly evolving mitochondrial genome is useful as a marker of species and strain identity and as a preliminary indication of evolutionary divergence within the genus Echinococcus.

Amino Acid Sequence↗
PubMed1992

Tumorigenicity of the met proto-oncogene and the gene for hepatocyte growth factor.

The met proto-oncogene is the tyrosine kinase growth factor receptor for hepatocyte growth factor/scatter factor (HGF/SF). It was previously shown that, like the oncogenic tpr-met, the mouse met proto-oncogene transforms NIH 3T3 cells. We have established NIH 3T3 cells stably expressing both human (Methu) and mouse (Metmu) met proto-oncogene products. The protein products are properly processed and appear on the cell surface. NIH 3T3 cells express endogenous mouse HGF/SF mRNA, suggesting an autocrine activation mechanism for transformation by Metmu. However, the tumor-forming activity of Methu in NIH 3T3 cells is very low compared with that of Metmu, but efficient tumorigenesis occurs when Methu and HGF/SFhu are coexpressed. These results are consistent with an autocrine transformation mechanism and suggest further that the endogenous murine factor inefficiently activates the tumorigenic potential of Methu. The tumorigenicity observed with reciprocal chimeric human and mouse receptors that exchange external ligand-binding domains supports this conclusion. We also show that HGF/SFhu expressed in NIH 3T3 cells produces tumors in nude mice.

3T3 Cells↗
PubMed1992

Population structure of Lankatrematoides gardneri (Digenea: Opisthotrematidae) in the pancreas of the dugong (Dugong dugon) (Mammalia: Sirenia).

The distribution among size and reproductive classes of the digenean Lankatrematoides gardneri was recorded from the pancreatic ducts of 41 dugongs from the Gulf of Papua, Papua New Guinea. Infrapopulation sizes ranged from 5 to 921 worms and showed no correlation with host age, sex, or month of capture. Immature worms tended to be concentrated in intermediate size classes, the largest immatures being no more numerous than matures. The mean proportion of mature worms in the 29 infrapopulations containing them was small (9.8%). Mature worms were significantly greater in mass than the largest immatures. There is evidence of an interaction between the presence or absence of mature worms and the distribution of immatures among classes.

Age Factors↗
PubMed1990

Structure, tissue-specific expression, and transforming activity of the mouse met protooncogene.

A 6.7-kilobase met complementary DNA (cDNA) was isolated from a pcD cDNA library prepared from C3H mouse fibroblast cell line polyadenylated RNA. Sequence analysis of 6.7-kilobase met cDNA insert revealed that it contained the entire open reading frame and shared an overall homology of 88.1% with the human met gene. Using the mouse met cDNA as probe, high levels of met expression were observed in the kidney, brain, lung, skin, and embryonic tissue as well as in several factor responsive mouse myeloid cell lines. Under SV40 promoter control, the mouse met protooncogene cDNA in the pCD vector was able to transform NIH 3T3 cells. These transformed cells possess multiple copies of mouse met cDNA and exhibit properties of malignant cells, including growth in soft agar and induction of tumors in nude mice. Tumor explant cell lines analyzed by Western blot also reveal the presence of high levels of Mr 170,000 and 140,000 met protein product(s).

Amino Acid Sequence↗
PubMed1989

Studies on cardiovascular fluke (Digenea: Spirorchiidae) infections in sea turtles from the Great Barrier Reef, Queensland, Australia.

Twenty-seven sea turtles (23 Chelonia mydas and four Eretmochelys imbricata) from northeast Queensland were found to be infected with cardiovascular flukes and/or their eggs. Five had originated from turtle farms in the Torres Strait, five from an oceanarium on Magnetic Island (146 degrees 56'E, 19 degrees S) and the remainder from coral reefs in the Torres Strait or near Townsville. The incidence of flukes and/or eggs in the groups was 4.8 per cent (5 of 104), 33.3 per cent (5 of 15) and 72.2 per cent (17 of 22), respectively. Affected animals ranged in size from 18 to 108 cm (curved carapace length) and weighed between 0.5 and 77 kg. The average number of flukes per host was 47. Flukes were recovered from the three chambers of the heart and major vessels (right aortic arch and brachiocephalic artery), where they were attached to the walls or free in the lumen. They were subsequently identified as Haplotrema spp. and/or Learedius spp. In 59.2 per cent (16 of 27) of turtles, flukes were not found, although their eggs were detected microscopically. Gross pathological changes associated with the presence of flukes included thickening and hardening of arterial walls (four turtles), thrombus formation (three), chronic pneumonia (two) and an excess of pericardial or peritoneal fluid (four). Microscopically, the essential changes was that of chronic inflammation, as evidenced by the proliferation of epithelial cells, reticulo-endothelial cells and fibroblasts in areas accessible to flukes and/or eggs. Multiple diffuse egg granulomas were a prominent feature of most organs, the spleen and lungs being predilection sites. Proliferative changes had occurred in the endocardium and in the endothelium of vessels supplying the spleen, stomach, intestine and pancreas (18 turtles). The walls of major arteries, lungs, liver, brain, crop and stomach were also acutely inflamed (eight turtles). Haemorrhage was recorded in the lungs and/or brain of eight turtles with heavy fluke infestations. Other vascular changes, viz. congestion, oedema and hypertrophy of arterial/arteriolar walls, resulted from the inhibition of blood flow by parasitic emboli.

Animals↗
PubMed1989

Restriction enzyme mapping of ribosomal DNA can distinguish between fasciolid (liver fluke) species.

Recognition sites for nine different restriction endonucleases were mapped on rDNA genes of fasciolid species. Southern blots of digested DNA from individual worms were probed sequentially with three different probes derived from rDNA of Schistosoma mansoni and known to span between them the entire rDNA repeat unit in that species. Eighteen recognition sites were mapped for Fasciola hepatica, and seventeen for Fasciola gigantica and Fascioloides magna. Each fasciolid species had no more than two unique recognition sites, the remainder being common to one or both of the other two species. No intraspecific variation in restriction sites was noted in F. hepatica (individuals from 11 samples studied; hosts were sheep, cattle and laboratory animals; geographical origins. Australia, New Zealand, Mexico, U.K., Hungary and Spain), or in F. gigantica (two samples; Indonesia and Malaysia). Only one sample of F. magna was available. One specimen of Fasciola sp. from Japan (specific identity regarded in the literature as uncertain) yielded a restriction map identical to that of F. gigantica. Almost all recognition sites occurred in or near the putative rRNA coding regions. The non-transcribed spacer region had few or no cut sites despite the fact that this region is up to about one half of the entire repeat unit in length. Length heterogeneity was noted in the non-transcribed spacer, even within individual worms.

Animals↗
PubMed1989

[Studies on oncogene and its products of human nasopharyngeal carcinoma].

Oncogene of nasopharyngeal carcinoma (NPC) by means of external origin DNA transfection experiment and its gene products by immunohistochemical method have been studied. These DNAs were isolated from human primary poorly differentiated NPC tissues and were transfected into NIH/3T3 mouse fibroblasts to induce the foci of the morphologically transformed cells in the culture, while DNAs of normal placenta tissues failed to do so. The DNAs were extracted from the primary and secondary transformed cells to analyse human sequence with human Alu sequence probe. The human sequence has been detected in the DNAs of the primary and secondary transformed foci cells, while none of the human sequence was detected in the DNAs of the control. The results indicated that human transforming sequences had been integrated into transformed cells. The malignant properties of the transformed foci cells were evidenced by tumorigenic experiment of nude mice. The transformed foci cells were inoculated subcutaneously in the nude mice and induced fibrosarcoma in vivo. The tumorigenic rate was 87.5%. It was further demonstrated that DNAs from human NPC possessed carcinogenicity and induced malignant transformation. The primary result revealed that the transforming gene of NPC may be homologue to Ha-ras oncogene. The expression of Ha-ras gene products-p21 has been studied in human NPC tissues. The primary results showed a positive expression of p21 in human NPC tissues by immunohistochemical method. The positive rate was 90.4%.

Animals↗
PubMed1988

Effects of subchronic inhalation of D-D (1,3-dichloropropene/1,2-dichloropropane) on reproduction in male and female rats.

The effects of inhaled D-D (1,3-dichloropropene/1,2-dichloropropane) on reproduction were studied in rats of both sexes. The rats inhaled nominal concentrations of 0, 10, 30, or 90 ppm (v/v) D-D for 6 hr/day, 5 days/week for 10 weeks. Treated males of proven fertility were paired with untreated virgin females at intervals during and after exposure. Treated females were paired with untreated males immediately after the 10-week exposure period. Various aspects of reproductive performance and general toxicity were assessed. Exposure to D-D produced no adverse effects on the libido, fertility, or morphology of the reproductive tracts of rats of either sex; no treatment-related dominant lethal effect was observed in male rats. Slight reductions in body weight gains and slight increases in liver and kidney weights were observed in 90 ppm rats of both sexes.

Allyl Compounds↗
PubMed1988

Correlation between H-ras p21TLeu61 protein content and tumorigenicity of NIH3T3 cells.

We have prepared a number of NIH3T3 clonal cell lines that contain an H-ras transforming gene with an A----T transversion at the 61st codon. The clonal lines contain 1 to 3 cell equivalents of the transforming oncogene and some lines look more morphologically transformed than others. Using Y13-238, a rat monoclonal antibody that recognizes H-ras p21 but not Ki- or N-ras in rodent cells, we found that the degree of morphological change is correlated with the relative amount of transforming protein in the selected clonal lines. Nude mice were injected with cells from lines containing different amounts of the transforming protein, ranging from approximately 1 to 10 times the level of normal H-ras protein present in NIH3T3 cells. Tumors arose in all mice that received cells containing the transforming protein. Their time of appearance (tumor latency) was correlated with the number of cells injected and the amount of transforming protein present in each clonal line; however, the subsequent rate of growth and ultimate size of the tumors were similar. Thus, it appears that the transforming protein has a significant effect on some early step in tumor development. Our results also show that relatively low amounts of transforming ras protein are sufficient to cause tumorigenicity in NIH3T3 cells and that higher amounts of the transforming protein cause proportionately faster responses.

Animals↗
PubMed1987

Causal role for an activated N-ras oncogene in the induction of tumorigenicity acquired by a human cell line.

ras oncogenes have been found in approximately 15% of the human tumors analyzed. However, a causal role for these genes in the tumorigenesis of human cells has yet to be shown. Tumorigenic late-passage PA-1 human teratocarcinoma cells (E-PA-1) contain an activated N-ras gene. In this report evidence is presented that nontumorigenic early passage revertant PA-1 cells (E-PA-1) contain only the germ-line protooncogene. Introduction by gene transfer of the activated L-PA-1 oncogene induces E-PA-1 cells to form tumors, suggesting that the activated N-ras oncogene has a causal role in the tumorigenesis of these cells.

Cell Adhesion↗
PubMed1987

The nubbin sign on computed tomography and sonography.

The loss of parenchyma in the lower pole of a kidney with a duplicated collecting system may mimic a mass on urography ("the nubbin sign"). Computed tomographic findings of this entity are diagnostic. The diagnosis may be difficult to make using sonography alone.

Adult↗
PubMed1987

Habitual daily energy expenditure and activity levels of lean and adult-onset and child-onset obese women.

The energy expenditure (EE) of eight lean, eight adult-onset obese (AOO), and eight child-onset obese (COO) women was determined over three 24-h periods by the factorial method, modified by subject-keypunched and mechanically recorded activity diaries. Mean daily EE was significantly higher in the pooled obese women (2472 +/- 488 kcal) than in lean women (1979 +/- 302 kcal) due to higher energy costs of sedentary and light activity in the obese. EE during moderate-to-strenuous activity was similar between groups because lean women performed these activities more vigorously. AOO and COO differed significantly in neither mean EE nor habitual activity. Fat-free mass (FFM) was a better predictor than body weight of both mean daily EE and the energy cost of activity. These data indicate that EE is positively related to obesity. Obese women tend to limit possible EE by reducing the vigorousness of weight-supported activity.

Activities of Daily Living↗