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Biomedical subjects

M Horne

Publications and source records attributed to M Horne.

At least 55 records · Page 3Linked to original sources
PubMed1990

Expression of the major gas vesicle protein gene in the halophilic archaebacterium Haloferax mediterranei is modulated by salt.

In the moderately to extremely halophilic archaebacterium Haloferax mediterranei gas vacuoles are not observed before the stationary phase of growth, and only when the cells are grown in media containing more than 17% total salt. Under the electron microscope, isolated gas vesicles appear as cylindrical structures with conical ends that reach a maximal length of 1.5 microns; this morphology is different from the spindle-shaped gas vesicles found in the Halobacterium halobium wild type which expresses the plasmid-borne p-vac gene, but resembles that of gas vesicles isolated from H. halobium strains expressing the chromosomal c-vac gene. Both the p-vac and the c-vac genes encode very similar structural proteins accounting for the major part of the "membrane" of the respective gas vesicles. The homologous mc-vac gene was isolated from Hf. mediterranei using the p-vac gene as probe. The mc-vac coding region indicates numerous nucleotide differences compared to the p-vac anc c-vac genes; the encoded protein is, however, almost identical to the c-vac gene product. The start point of the 310 nucleotide mc-vac transcript determined by primer extension analysis and S1 mapping was located 20 bp upstream of the ATG start codon, which is at the same relative position as found for the other two vac mRNAs. During the growth cycle, mc-vac mRNA was detectable in Hf. mediterranei cells grown in 15% as well as 25% total salt, with a maximal level in the early stationary phase of growth. The relative abundance of mc-vac mRNA in cells grown at 25% salt was sevenfold higher than in cells grown in 15% total salt.

Amino Acid Sequence↗
PubMed1989

Expression of two gas vacuole protein genes in Halobacterium halobium and other related species.

The archaebacterium Halobacterium halobium contains two genes encoding gas vacuole proteins (vac). One resides on a large naturally occurring plasmid and encodes a protein of 76 amino acids (p-vac), while the other is a chromosomal gene that encodes a highly similar protein of 79 amino acids (c-vac). Northern analysis determined the c-vac and p-vac mRNA to be approximately 340 nucleotides in length, and S1 mapping of both transcripts indicated that the 5' terminus for each starts at the same relative nucleotide. Three other Halobacterium species producing gas vacuoles were investigated, H. spec. GN101, YC819-9, and SB3. All three contain only a chromosomal c-vac gene, and the 5' terminus of the 340 nucleotide mRNA starts at the same nucleotide as found for H. halobium. The c-vac gene region of H. spec. GN101 contains nine nucleotide exchanges, three of which occur in the coding region with no effect on the amino acid sequence. In contrast, the c-vac gene of H. spec. SB3 has an identical nucleotide sequence to the H. halobium c-vac gene. Gas vacuole production in each of these species was monitored during culture growth by phase contrast microscopy, and the vac mRNA level was determined for each time point. H. halobium p-vac deletion mutants, as well as the halobacterial species GN101 and YC819-9, start to synthesize gas vacuoles in early stationary growth phase with a maximal mRNA content in stationary phase. In contrast, H. halobium wild-type synthesizes gas vacuoles exclusively due to p-vac gene expression with a maximal mRNA level during logarithmic growth, and transcripts of the c-vac gene were not detectable.(ABSTRACT TRUNCATED AT 250 WORDS)

Archaeal Proteins↗
PubMed1989

Postoperative absorption of controlled-release morphine sulphate. A study in patients given no parenteral opioids.

The absorption of morphine sulphate in a controlled-release formulation was studied in 12 patients who had undergone unilateral inguinal hernia repair under a light general anaesthetic and ilio-inguinal block. Serum morphine concentrations were measured serially and gastric emptying was assessed by measurement of paracetamol absorption. Three patients had delayed gastric emptying and impaired morphine absorption in the immediate postoperative period. Four hours later, there was a significant reduction in gastric emptying in eight patients who had normal paracetamol and morphine absorption in the immediate postoperative period.

Absorption↗
PubMed1989

Genome structure of Halobacterium halobium: plasmid dynamics in gas vacuole deficient mutants.

Halobacterium halobium contains two gas vacuole protein genes that are located in plasmid pHH1 (p-vac) and in the chromosomal DNA (c-vac). The mutation frequency for these genes is different: the constitutively expressed p-vac gene is mutated with a frequency of 10(-2), while the chromosomal gene expressed in the stationary phase of growth is mutated with a frequency of 10(-5). The difference in the mutation susceptibility is due to the dynamics of plasmid pHH1. p-vac gene mutations are caused (i) by the integration of an insertion element or (ii) by a deletion event encompassing the p-vac gene region. In contrast, c-vac mutants analyzed to date incurred neither insertion elements nor deletions. Deletion events within pHH1 occur at high frequencies during the development of a H. halobium culture. The investigation of the fusion regions resulting from deletion events indicates that insertion elements are involved. The analysis of pHH1 deletion variants led to a 4 kilobase pair DNA region containing the origin of replication of the pHH1 plasmid.

Archaeal Proteins↗
PubMed1988

Two genes encoding gas vacuole proteins in Halobacterium halobium.

The archaebacterium Halobacterium halobium contains two related gas vacuole protein-encoding genes (vac). One of these genes encodes a protein of 76 amino acids and resides on the major plasmid. The second gene is located on the chromosome in a (G + C)-rich DNA fraction and encodes a slightly larger but highly homologous protein consisting of 79 amino acids. The plasmid encoded vac gene is transcribed constitutively throughout the growth cycle while the chromosomal vac gene is expressed during the stationary phase of growth. Comparison of the nucleotide sequences of the two genes indicates differences in the putative promoter regions as well as 35 single base-pair exchanges within the coding regions of the two genes. The majority of the nucleotide exchanges in the coding region occur in the third position of a codon triplet generating the codon synonym. The only differences between the two encoded proteins are the exchange of 2 amino acids (positions 8 and 29) and a deletion of 3 amino acids near the carboxy-terminus of the plasmid encoded vac protein. The genomic DNAs from other halobacterial isolates (Halobacterium sp. SB3, GN101 and YC819-9) were found to contain only a chromosomal vac gene copy. There is a high conservation of the chromosomal vac gene and the genomic region surrounding it among the halobacterial strains investigated.

Amino Acid Sequence↗
PubMed1988

Acute myopathy in severe acute asthma treated with intravenously administered corticosteroids.

An association between the use of parenteral corticosteroids in acute asthma and the development of an acute myopathy was first reported in 1977. We report 2 further cases that contribute significantly to our knowledge of this rare complication of the treatment of acute asthma. These cases demonstrate that the acute myopathy is not just a complication of the use of parenteral hydrocortisone in patients requiring ventilatory support during an episode of acute asthma. The acute myopathy can occur with several parenteral corticosteroids, may be severe (with rhabdomyolysis and myoglobinuria), and may have protracted morbidity. Prospective follow-up allowed demonstration of histopathology, electrophysiology, and also the contribution of various pharmacologic agents. Careful analysis of the evidence strongly implicates corticosteroids as the causative agent.

Acute Disease↗
PubMed1987

Inhibition of thrombin-induced platelet aggregation by uteroglobin.

Uteroglobin, a steroid-dependent, small molecular weight (15K) protein in the rabbit, inhibited thrombin-induced aggregation of both rabbit and human gel-filtered platelets (GFP). GFP aggregation by arachidonic acid was not affected by uteroglobin. There were no effects of uteroglobin on thrombin-induced clotting of plasma or purified fibrinogen, or inhibition of thrombin by antithrombin III. Additionally, preliminary results suggest that uteroglobin does not interfere with binding of thrombin to platelets. We suggest that inhibition of platelet aggregation by uteroglobin may function in preventing thrombosis and ensuring free flow of blood through the microvasculature of the uterus and the placenta and may induce some of the antimotility effects of progesterone on the uterus.

Animals↗
PubMed1987

Anorexia nervosa: an object relations approach to primary treatment.

Concurrent behaviour therapy and psychotherapy in the treatment of anorexia nervosa creates significant problems in the development of a therapeutic alliance and in the multiple roles staff are required to assume. Our protocol was developed to keep treatment personnel in their usual roles so that their various treatment skills could be fully utilised. A physician treated the anorexia with naso-gastric feeding, freeing the psychotherapist to act in the usual manner. This avoided role confusion, and the split of 'bad' and 'good' treatment personnel was appropriate and therapeutic, rather than pathological. Four successful cases are described.

Adolescent↗
PubMed1985

Availability of drug assay results and dosage advice improves antiepileptic care in a specialist neurology outpatient clinic.

The incidence of grand mal seizures, distribution of drug levels relative to the therapeutic range and the incidence of side effects were monitored before and after the provision of same-day preconsultation assay results (phenytoin and carbamazepine) to an epilepsy clinic. A total of 300 patients completed the study. The proportion of patients fitting fell from 23.3% at entry to 10% at review (P less than 0.01) while the incidence of side effects fell from 30.7% to 17.3% (P less than 0.01) and the proportion of phenytoin levels in the therapeutic range rose from 41% to 58% (P less than 0.01). Similar patterns were observed in 111 patients who entered the study during a control observation period. The provision of appropriate support services (assay results and dosage advice) to specialist epilepsy clinics allows improvement in the management of epilepsy.

Adolescent↗
PubMed1982

Expectation and the blood-pressure-lowering effects of relaxation.

In a study of the blood-pressure-lowering effects of relaxation training in patients with essential hypertension, instructions concerning the relaxation procedure were varied so that one group was told to expect delayed blood-pressure-lowering and the other group immediate lowering. The systolic blood pressure decrease during the training period in the immediate lowering group was 17.0 mm Hg, compared with 2.4 mm Hg for the delayed group (p = 0.001). Diastolic blood pressure changes were not significantly different. Measures of therapy credibility and perceived relaxation failed to differentiate the groups. The implications of these findings for future research and for clinical practice are considered.

Adult↗
PubMed1978

Dust from carbon fibre.

Carbon fibre, manufactured from a polyacrylonitrile fibre precursor, is used to reinforce plastic in the aircraft industry. When carbon fibre was fed into a hammer mill, only low concentrations of dust of respirable size could be produced and less than 1% of the respirable carbon particles were fibrous. The dust cloud contained a few transparent fibres, probably glass, of respirable size. When the dust was inhaled by guinea pigs nonfibrous particles were phagocytosed. The few carbon fibres found in the lung that were longer than 5 microns were still extracellular after 27 weeks and they were uncoated. No free transparent fibres were found in the lungs but fibre bodies with a ferruginous coating were probably derived from the transparent fibres. No pathological effects were observed.

Animals↗