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Biomedical subjects

J Ellis

Publications and source records attributed to J Ellis.

At least 181 records · Page 10Linked to original sources
PubMed1994

Attenuated hypercholesterolemic response to a high-cholesterol diet in subjects heterozygous for the apolipoprotein A-IV-2 allele.

BACKGROUND: Previous studies have suggested that the variant apolipoprotein (apo) allele apo A-IV-2 may influence the response of the plasma cholesterol concentration to dietary cholesterol. METHODS: We measured plasma lipids and lipoproteins in 11 subjects who were heterozygous for the apo A-IV-2 allele (apo A-IV-1/2 heterozygotes) and a control group of 12 subjects who were homozygous for the common apo A-IV allele (apo A-IV-1/1 homozygotes) in an outpatient dietary-modification study. (Approximately one in seven persons in the United States is a heterozygote.) The subjects consumed a low-cholesterol diet (about 200 mg [0.5 mmol] of cholesterol per day) during a two-week run-in period; daily cholesterol intake was then increased to approximately 1100 mg (2.8 mmol) by the addition of four egg yolks per day. RESULTS: The fat intake and the ratio of polyunsaturated to saturated fat were similar in the two groups throughout the study. After three weeks of egg intake, the mean plasma total cholesterol increased by 22 mg per deciliter (0.57 mmol per liter) in the apo A-IV-1/1 group, but by only 6 mg per deciliter (0.15 mmol per liter) in the apo A-IV-1/2 group (P = 0.05). The mean plasma low-density lipoprotein cholesterol increased by 19 mg per deciliter (0.49 mmol per liter) in the apo A-IV-1/1 group, but by only 1 mg per deciliter (0.03 mmol per liter) in the apo A-IV-1/2 group (P = 0.03). There were no changes in the plasma triglyceride or high-density lipoprotein cholesterol concentrations in either group. CONCLUSIONS: The apo A-IV-2 allele attenuates the hypercholesterolemic response to the short-term ingestion of a very-high-cholesterol diet and may partially account for the heterogeneous response to dietary cholesterol. However, cholesterol intake in this study was more than twice that of the general population; whether the apo A-IV-2 allele alters responsiveness at lower levels of cholesterol intake remains to be determined.

Adult↗
PubMed1994

The kinetics of the interaction between the actin-binding domain of alpha-actinin and F-actin.

Measurement of the binding equilibrium for the interaction of alpha-actinin with F-actin is complicated by secondary reactions involving cross-linking and/or bundling of the actin filaments. To quantitate the initial binding event, we studied the interaction of the bacterially expressed actin-binding domain (ABD) of chick smooth muscle alpha-actinin with F-actin. Stopped-flow measurements revealed a quench in protein fluorescence and an enhancement in light scattering when ABD binds to F-actin yielding second order rate constants for association of 2 x 10(5), 1.8 x 10(6) and 4 x 10(6) M-1.s-1 at 5 degrees C, 15 degrees C and 25 degrees C, respectively. At the latter two temperatures the dissociation rate constants were 1.5 and 9.6s-1, giving equilibrium constants of 0.83 and 2.4 microM, respectively. Optical changes on mixing intact alpha-actinin with F-actin were dominated by secondary bundling events.

Actinin↗
PubMed1994

An empirical comparison of distance matrix techniques for estimating codon usage divergence.

The quantitative description of codon usage divergence among taxa is a two-step process involving first the calculation of a standardized measure of intertaxon divergence for each possible pair of taxa followed by a summary and visual display of the patterns among the taxa inherent in these measures. Three different measures have been proposed in the literature, and three different summaries have been used. These different techniques are empirically compared using a data set consisting of gene sequences from seven species of Apicomplexa. The results suggest that the manhattan distance measure may be preferable to the use of the chi-square measure, although the separation of amino acid usage and codon usage by the genetic distance produces theoretical advantages. The multidimensional scaling ordination and unweighted pair-group clustering are both successful in displaying the patterns, while the eigenanalysis ordination is not.

Animals↗
PubMed1994

The phylogeny of Neospora caninum.

Morphological studies by electron microscopy on the protozoan Neospora caninum have shown that this organism possesses a subcellular structure typical of parasites classified in the family Sarcocystidae, subclass Coccidiasina of the phylum Apicomplexa. Using a strategy based on DNA sequence analysis of products derived by asymmetric PCR to determine the nucleotide sequences, we have tested the validity of this classification by comparing the small subunit ribosomal RNA (18S rRNA) gene sequences of N. caninum with those of other parasitic protozoa classified in the phylum Apicomplexa. The results of this analysis confirm the placing of N. caninum in the family Sarcocystidae and place it as a sister group to Toxoplasma gondii in the phylum Apicomplexa.

Animals↗
PubMed1994

Acute ammonium dichromate poisoning.

We report the ingestion of ammonium dichromate by a child that resulted in multiple-organ-system failure and death. Exchange transfusion and hemodialysis were ineffective in removing significant amounts of chromium or causing sustained clinical improvement. We suggest that immediate, large doses of the reducing agent ascorbic acid would allow effective reduction of hexavalent chromium with less cellular toxicity.

Chromates↗
PubMed1994

Lyme disease: a search for a causative agent in ticks in south-eastern Australia.

Attempts were made to identify the causative organism of Lyme disease in Australia from possible tick vectors. Ticks were collected in coastal areas of New South Wales, Australia, from localities associated with putative human infections. The ticks were dissected; a portion of the gut contents was examined for spirochaetes by microscopy, the remaining portion inoculated into culture media. The detection of spirochaetes in culture was performed using microscopy, and immunochemical and molecular (PCR) techniques. Additionally, whole ticks were tested with PCR for spirochaetes. From 1990 to 1992, approximately 12,000 ticks were processed for spirochaetes. No evidence of Borrelia burgdorferi or any other spirochaete was recovered from or detected in likely tick vectors. Some spirochaete-like objects detected in the cultures were shown to be artifacts, probably aggregates of bacterial flagellae. There is no definitive evidence for the existence in Australia of B. burgdorferi the causative agent of true Lyme disease, or for any other tick-borne spirochaete that may be responsible for a local syndrome being reported as Lyme disease.

Animals↗
PubMed1994

Trisomy 12 in B-cell chronic lymphocytic leukaemia: assessment of lineage restriction by simultaneous analysis of immunophenotype and genotype in interphase cells by fluorescence in situ hybridization.

We have studied the lineage restriction of trisomy 12 in six patients with B-cell chronic lymphocytic leukaemia (CLL) by simultaneous analysis of immunophenotype and fluorescence in situ hybridization (FISH) signals in single interphase cells. Fresh uncultured cells from each patient were immunophenotyped by the alkaline phosphatase anti-alkaline phosphatase method (APAAP) using monoclonal or polyclonal antibodies and hybridized with a chromosome 12 specific alpha-satellite DNA probe. In all cases trisomy 12 was restricted to the clonal B-cells, kappa positive or lambda positive, whereas T-cells (CD3 positive) and non clonal B-cells had only two chromosome 12 signals. Within the clonal B-cell population a large proportion of cells were disomic for chromosome 12, whilst trisomic cells ranged from 21% to 37%. The absence of trisomy 12 in T-cells and the mosaicism demonstrated in the clonal B-cells suggests that this abnormality is a secondary event during the leukaemic transformation of CLL and develops in an already established neoplastic B-cell population.

Aged↗
PubMed1994

Subungual keratoacanthoma--a report of four cases and review of the literature.

Subungual keratoacanthoma is a rare benign neoplasm which most commonly occurs in middle-aged Caucasians. It usually presents as a painful, rapidly growing lesion of the terminal phalanx. Radiography consistently demonstrates a well-defined cup-shaped erosion of the underlying bone. Clinically, subungual keratoacanthoma must be distinguished from subungual squamous carcinoma. We report four further cases and discuss the literature.

Adult↗
PubMed1994

Osteonecrosis following treatment for Hodgkin's disease.

Osteonecrosis is usually considered to be a minor and rare late sequelae of treatment for Hodgkin's Disease (HD). However, over ten years six patients out of a total of 53 patients treated for HD at the haematology department of a district general hospital developed osteonecrosis, an incidence of 11.3%. Routine isotope bone scanning of patients produced two further asymptomatic cases. These results suggest a higher incidence than previously suspected of a problem which caused our patients considerable morbidity. Further measures are required to identify and adequately treat a significant cause of late morbidity following chemotherapy for HD.

Adolescent↗
PubMed1994

Tumour necrosis factor production by monocytes from cattle infected with Trypanosoma (Duttonella) vivax and Trypanosoma (Nannomonas) congolense: possible association with severity of anaemia associated with the disease.

Plasma of cattle infected with Trypanosoma vivax IL2337 was analysed for the presence of bovine tumour necrosis factor (TNF) by EIA in which TNF was captured by a monoclonal antibody (MoAb BC9) and detected by a rabbit polyclonal antiserum. At week 2-3 post infection (p.i.) only a low activity was detected. Therefore, an alternative approach was used in which TNF production was measured ex vivo. Monocytes from T. vivax IL2337-infected cattle manifested a strong TNF production which peaked around week 2 1/2 p.i. Monocytes from pre-infection controls did not produce significant concentrations of TNF. In contrast to the strong production of TNF by monocytes from cattle infected with T. vivax IL2337, TNF production was not detected from monocytes of cattle infected with Trypanosoma congolense ILNat 3.1. Trypanosomiasis due to these parasites differs in the degree if anaemia as indicated by packed cell volume (PCV). T. vivax IL2337 causes a severe, acute PCV fall whereas T. congolense ILNat 3.1. causes a more gradual fall in PCV.

Anemia↗
PubMed1994

The periodontal problems and management of the renal transplant patient.

This review considers the periodontal problems of renal transplant patients with particular reference to their drug therapy and the pretransplant uremia. It would appear that either disease- or drug-induced immunosuppression affords the renal transplant patient a degree of "protection" against periodontal breakdown. However, of more significance to the periodontologist is the problem of drug-induced gingival overgrowth with reference to both cyclosporin and nifedipine. Approximately 30% of dentate renal transplant patients medicated with cyclosporin alone experience significant gingival overgrowth which requires surgical excision. This figure increases to 40% when patients are medicated with both drugs. The pathogenesis of this unwanted effect is uncertain and the relationship between the expression of gingival overgrowth and various periodontal or pharmacokinetic variables remains a contentious issue. Clinical measures to prevent the occurrence of either cyclosporin- or nifedipine-induced gingival overgrowth are unsatisfactory.

Chronic Disease↗
PubMed1993

Design and specificity of hammerhead ribozymes against calretinin mRNA.

We obtained a partial sequence of mouse calretinin mRNA from cDNA clones, and designed hammerhead ribozymes to cleave positions within it. With a view to optimising hammerhead ribozymes for eliminating the mRNA in vivo, we varied the length and sequence of the three duplex 'arms' and measured the cleavage of long RNA substrates in vitro at 37 degrees C (as well as 50 degrees C). Precise cleavage occurred, but it could only go to completion with a large excess of ribozyme. The evidence suggests that the rate-limiting step with a large target is not the cleavage, but the formation of the active ribozyme: substrate complex. The efficiency varied unpredictably according to the target site, the length of the substrate RNA, and the length of the ribozyme; secondary structure in vitro may be responsible. We particularly investigated the degree of sequence-specificity. Some mismatches could be tolerated, but shortening of the total basepairing with the substrate to less than 14 bp drastically reduced activity, implying that interaction with weakly-matched RNAs is unlikely to be a serious problem in vivo. These results suggest that specific and complete cleavage of a mRNA in vivo should be possible, given high-level expression of a ribozyme against a favourable target site.

Animals↗
PubMed1993

Trisomy 12 in chronic lymphocytic leukemia detected by fluorescence in situ hybridization: analysis by stage, immunophenotype, and morphology.

Fluorescence in situ hybridization (FISH) with a chromosome 12 specific alpha-centromeric probe was performed on interphase cells from 183 patients with B-cell chronic lymphocytic leukemia (CLL). Twenty one cases with trisomy 12 (11.5%) were detected. The number of trisomic cells ranged from 5.5% to 76% (mean 38.5%). No correlation was found between the presence of trisomy 12 and white blood cell count, hemoglobin level, platelet count, a specific immunophenotype, clinical stage, sex, splenomegaly, or lymphadenopathy. Morphologic review of all cases with trisomy 12 showed seven (33%) with more than 10% prolymphocytes and three (14%) with CLL of mixed cell type. While trisomy 12 is the most common chromosomal abnormality in CLL, it is more frequent in morphologically atypical cases, some of which may be undergoing transformation. There was a statistically significant difference in the incidence of atypical cases between those with (47%) and without (7.6%) trisomy 12 (P < .001). It remains to be determined whether this abnormality is associated with a worse prognosis; this is currently being investigated in the context of a national therapeutic trial. The technique used is more sensitive than conventional cytogenetic analysis, which in this series failed to detect trisomy 12 in six cases. FISH allows the systematic study on a large number of patients without the need of metaphase preparations.

Antigens, CD↗
PubMed1993

Analysis of dinucleotide frequency and codon usage in the phylum Apicomplexa.

Dinucleotide frequency (DiF) and codon usage (cu) were analysed in gene sequences from four parasitic protozoa, Babesia bovis, Theileria parva, Toxoplasma gondii and Eimeria tenella, of the phylum Apicomplexa. In keeping with the 'genome hypothesis', cu was found to be non-random and species specific in these organisms, although cu among members of the same subclass was found to be very similar. Several low-usage (lu) codons were identified, and the usage of lu codons appears to be related to the taxonomic position of the organisms under study. A comparison of the observed/expected DiF ratios obtained from gene coding regions revealed a low frequency of the TA and CG dinucleotides in all organisms studied. A comparison of these DiF ratios with those found in rRNA-encoding genes and in introns, showed that in the parasites, B. bovis and Th. parva (representing the piroplasms), the low frequency of dinucleotides appeared to be the result of coding pressure alone. In T. gondii and E. tenella (representing the coccidia), however, coding pressure could not completely explain differences in DiF.

Animals↗