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Biomedical subjects

J M Lucas

Publications and source records attributed to J M Lucas.

At least 19 recordsLinked to original sources
PubMed1999

Post operative performance of racing Standardbreds treated arthroscopically for carpal chip fractures: 176 cases (1986-1993).

A retrospective study of 176 Standardbred horses that had arthroscopic surgery for carpal chip fractures over a 7 year period was done in order to determine fracture location and post operative performance. Chip fractures of the proximal third carpal bone and the distal radiocarpal bone occurred with equal frequency (49.2 and 49.6% respectively), and chip fractures involving the antebrachiocarpal joint were rare. Trotters had significantly more third carpal bone lesions than radiocarpal bone lesions when compared to pacers (P = 0.0304). Seventy-four per cent of horses made at least one start following surgery. Pacers were significantly more likely to have at least one start after surgery than were trotters (P = 0.0009). Median earnings per start significantly decreased after surgery (P = 0.0081), while median race mark significantly increased after surgery (P = 0.0100). It is concluded that the majority of Standardbreds will be useful racehorses following carpal arthroscopy; however, most earn less money per start and many race at a lower class.

Animals↗
PubMed1997

A physiological evaluation of carbon sources for calcification in the octocoral Leptogorgia virgulata (Lamarck).

The union of calcium cations with carbonate anions to form calcium carbonate (CaCO3) is a fundamentally important physiological process of many marine invertebrates, in particular the corals. In an effort to understand the sources and processes of carbon uptake and subsequent deposition as calcium carbonate, a series of studies of the incorporation of 14C-labeled compounds into spicules was undertaken using the soft coral Leptogorgia virgulata. It has been surmised for some time that dissolved inorganic carbon in sea water is used in the biomineralization process. Furthermore, it was suspected that metabolically generated CO2 is also available for calcification. As a means of testing these possible sources of carbon in spicule calcification, key enzymes or transport systems in each pathway were inhibited. First, the enzyme carbonic anhydrase was specifically inhibited using acetazolamide. Second, the active transport of bicarbonate was inhibited using DIDS (4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid). Third, CO2 generation resulting from glycolysis and the citric acid cycle was arrested using iodoacetic acid, which interferes specifically with the enzyme glyceraldehyde-3-phosphate dehydrogenase. The results indicate that dissolved CO2 is the largest source of carbon used in the formation of calcitic sclerites, followed by HCO3- from dissolved inorganic carbon. In L. virgulata, the dissolved inorganic carbon is responsible for approximately 67% of the carbon in the sclerites. The other 33% comes from CO2 generated by glycolysis. Two important conclusions can be drawn from this work. First, carbon for spiculogenesis comes not only from dissolved inorganic carbon in the environment but also from metabolically produced carbon dioxide. While the latter has been theorized, it has never before been demonstrated in octocorals. Second, regardless of the carbon source, the enzyme carbonic anhydrase plays a pivotal role in the physiology of spicule formation in Leptogorgia virgulata.

Animals↗
PubMed1996

FRAXE mutation analysis in three Spanish families.

Very little is known about the phenotype of FRAXE-positive individuals and the relation between the genotype/phenotype and genotype/ cytogenetic expression. We describe three families with normal and mildly affected individuals and a severely retarded male expressing fragility at the FRAXE locus or presenting different expansions at the CGG FRAXE triplet. In addition, we analyze the FRAXE mutation in sperm DNA from a retarded male carrier with a handicapped daughter expressing fragility at the FRAXE locus. Mental status in FRAXE individuals is highly variable and, although mild mental retardation is observed in most cases, several carrier males are apparently normal. It seems that methylation is not as strictly associated with size of CGG triplets in the FRAXE locus as in FRAXA, and it is possible that normal carrier individuals with fully methylated increments in lymphocytes have a certain proportion of unmethylated alleles in the critical (i.e., neural) tissues, FRAXE mutation is apparently similar to FRAXA in that males with somatic large methylated increments are carriers of small unmethylated ones in germinal cells.

Adolescent↗
PubMed1995

Regulation of FGF-4 enhancer activity by transcription factor NF-Y.

Regulation of FGF-4 gene expression is controlled both by elements in the promoter and by an enhancer domain located in the untranslated region of the third exon. We have determined that transcription factor NF-Y binds to the FGF-4 promoter. We further show by mutational analysis that binding of NF-Y is essential for FGF-4 enhancer activity but has minimal effect on activity of the FGF-4 promoter alone.

Animals↗
PubMed1994

[Infection with hepatitis B and C viruses in the mentally retarded].

AIM: To study the prevalence of hepatitis C virus infection (HCV) and the associated risk factors in an institution for the mentally retarded, in addition to its relation with hepatitis B infection (HBV). METHODS: The presence of antibodies against the HCV (anti-HCV) and markers for the HBV was evaluated in 94 mentally retarded subjects admitted to a single institution. Information concerning the sex, age, length of admission, type and degree of mental retardation, history of sexual promiscuity, surgery and blood transfusions was collected in every individual. RESULTS: The prevalence of infection by HBV was 22.3%. Only one individual was detected as being positive for the HCV.

Adolescent↗
PubMed1994

The FGF-4 promoter is required for transformation and is active in both embryonal and somatic cells.

We report the independent isolation of a rearranged FGF-4 gene from a patient with chronic myeloid leukaemia. We show that the FGF-4 gene has been truncated 30 nucleotides 3' to the coding sequence and has been fused to the RNA processing signals from a putative unknown gene on chromosome 15. We demonstrate that the promoter region of the FGF-4 gene is active in NIH3T3 cells and is indeed necessary for transformation. Using the luciferase reporter assay we have shown that the FGF-4 5' flanking sequences possess easily detectable promoter activity in both F9 and HeLa cell lines. 5' deletion analysis of the FGF-4 promoter has delineated regions containing cis-acting elements of functional importance. These regulatory regions are common to both embryonal and somatic cell lines. Electrophoretic mobility shift assay, using nuclear extracts from F9 and HeLa cells, has allowed detection of DNA-protein interactions occurring in the functionally significant regions. Subsequent comparison of the human and murine FGF-4 promoters show that the regions of functional significance are highly conserved. We suggest that the FGF-4 gene may be suppressed through a distal suppressor locus and becomes active when separated from this suppressor.

3T3 Cells↗
PubMed1993

c-MYC repression of promoter activity through core promoter elements.

c-MYC was found to repress expression of the c-myc promoter in a transient assay system. Deletion constructs showed the cis-acting element(s) were common to both the P1 and P2 promoters. Further analysis involving replacement of the P2 TATA box and initiator elements with the SV40 late promoter initiator localized the cis-acting elements to the core promoter.

Dose-Response Relationship, Drug↗
PubMed1981

Effect of analytical variability on measurements of population blood lead levels.

The effect of analytical error on the interpretation of blood lead data obtained from population studies is discussed. Statistical analysis of measured blood lead values reported in four representative population studies shows over 40 percent of the variability in blood lead measurements is due to analytical error. Because of this analytical error, a large percentage of the observed lead measurements which exceed a threshold limit are "false positives" in that the true blood lead values for these individuals do not exceed the threshold. The EPA has suggested that the distribution of blood lead values could be used as a guide for determining the portion of a population at risk. "At risk" is defined as having blood lead values above a certain threshold. If this is done, the effect of analytical error which causes "false positives" should be considered properly to obtain an accurate estimate of the population at risk.

Analysis of Variance↗
PubMed1976

The synchronization of oestrus and subsequent fertility in ewes following treatment with a synthetic prostaglandin analogue (ONO 453).

ONO 453, a synthetic analogue of prostaglandin F2alpha (PGF2alpha) is a potent luteolytic agent in cycling ewes when given as a single intramuscular injection. The drug was effective in doses of 2 mg when administered after day 3 of the oestrous cycle. It is well tolerated by ewes, producing no apparent signs of toxicity at 5 mg and only a mild transient increase in the respiratory rate at 10 mg. To synchronise oestrus two dosing regimens were examined; a single i.m. dose of 2 mg administered without reference to the day of the oestrous cycle, and 2 injections of 2 mg administered 7 days apart. With the first method 86.6 per cent of the ewes were in oestrus within 24-50 hours of treatment, with the second, 82 per cent were in oestrus within 30-54 hours. To test the fertility of the oestrus following ONO 453-induced luteolysis, both groups of ewes were run with fertile rams and 86 per cent and 70.8 per cent of those induced by the single or double injection respectively, conceived and lambed.

Animals↗