Assessment of clinical competence using objective structured examination.

To avoid many of the disadvantages of the traditional clinical examination we have introduced the structured clinical examination. In this students rotate round a series of stations in the hospital ward. At one station they are asked to carry out a procedure, such as take a history, undertake one aspect of physical examination, or interpret laboratory investigations in the light of a patient''s problem, and at the next station they have to answer questions on the findings at the previous station and their interpretation. As they cannot go back to check on omissions multiple-choice questions have a minimal cueing effect. The students may be observed and scored at some stations by examiners using a check list. In the structured clinical examination the variables and complexity of the examination are more easily controlled, its aims can be more clearly defined, and more of the student''s knowledge can be tested. The examination is more objective and a marking strategy can be decided in advance. The examination results in improved feed-back to students and staff.     

Inhibition of Virus Release by Antibodies to Surface Antigens of Influenza Viruses

When influenza virus was mixed with antisera to its surface subunits before inoculation of cell cultures, anti-hemagglutinin antibodies neutralized infectivity but anti-neuraminidase did not. When the antisera were added after infection of cell cultures, anti-hemagglutinin and anti-neuraminidase antibodies were equally effective in reducing virus titers in culture fluids. Decreased virus titers were not due to interference of antibody with assay and were not accompanied by a reduction in the synthesis of hemagglutinin and neuraminidase subunits. Both antisera also effectively prevented in vitro virus spread. Inhibition of virus release by neuraminidase antibody appeared unrelated to its antienzyme property. Hydrolysis of N-acetyl neuraminic acid residues of infected host cells proceeded unimpaired in the presence of subunit antisera. Anti-hemagglutinin and anti-neuraminidase antibodies may act to prevent virus release by binding newly formed virus subunits to each other and to anti-genically altered cell membranes.     

A difference in sensitivity to alpha-adrenergic agonists exhibited by detrusor and bladder neck of rabbit.

In cumulative dose-response studies, strips from bladder neck of rabbit were significantly more sensitive to stimulation with noradrenaline, phenylephrine, and methoxamine than were strips from detrusor. There was no difference between the two regions in sensitivity to isoprenaline or carbachol. From the known characteristics of these agents, it seemed unlikely that metabolic destruction or uptake could account for the different sensitivities seen. Also, neither normetanephrine nor desmethylimipramine could alter significantly the potency of noradrenaline in either area of the bladder. It seems likely that the difference in sensitivity to alpha-adrenoceptor stimulation in the bladder neck and detrusor is due to factors at the receptor level.     

The Rhizobium leguminosarum nodulation gene nodF encodes a polypeptide similar to acyl-carrier protein and is regulated by nodD plus a factor in pea root exudate

The DNA sequence of ~3.5 kb of the nodulation (nod) region of the Rhizobium leguminosarum symbiotic plasmid pRL1JI was determined. Three open reading frames were identified; genes corresponding to these have been called nodD, nodE and nodF.nodD is adjacent to nodA and is transcribed in the opposite direction. The nodF and nodE genes are downstream of, and transcribed in the same direction as, nodD with 667 nucleotides between nodD and nodF and three nucleotides separating nodF and nodE. The induction of the nodFE operon requires the nodD gene product and a component present in plant root exudate. Regions of DNA sequence preceding nodF are similar to those preceding nodA; these sequences may be involved in the regulation of the expression of nodA and nodF. Analysis of nodD revealed an amino acid sequence similar to the predicted DNA-binding domain of known DNA-binding proteins. A protein comparison of the nodF protein showed it to be similar to the acyl-carrier protein from Escherichia coli and barley, especially around the pantothenate-binding region and on this basis it is thought that this protein may be involved in an acyl transfer reaction.     

Assembly of the adenosine triphosphatase complex in Escherichia coli: assembly of F0 is dependent on the formation of specific F1 subunits.

A strain of Escherichia coli (AN1007) carrying the polar uncD436 allele which affects the operon coding for the F1-F0 adenosine triphosphatase (ATPase) complex was isolated and characterized. The uncD436 allele affected the two genes most distal to the operon promoter, i.e., uncD and uncC. Although the genes coding for the F0 portion of the ATPase complex were not affected in strains carrying this mutant allele, the lack of reconstitution of washed membranes by normal F1 ATPase suggested that a functional F0 might not be formed. This conclusion was supported by the observation that the 18,000-molecular-weight F0 subunit, coded for by the uncF gene, was absent from the membranes. Plasmid pAN36 (uncD+C+), when inserted into a strain carrying the uncD436 allele, resulted in the incorporation of the 18,000-molecular-weight F0 subunit into the membrane. A further series of experiments with Mu-induced polarity mutants, with and without plasmid pAN36, showed that the formation of both the alpha- and beta-subunits of F1 ATPase was an essential prerequisite to the incorporation into the membrane of the 18,000-molecular-weight F0 subunit and to the formation of a functional F0. Examination of the polypeptide composition of membranes from various unc mutants allowed a sequence for the normal assembly of the F1-F0 ATPase complex to be proposed.     

Respiration-driven proton translocation by yeast mitochondria with differing efficiencies of oxidative phosphorylation

Measurements were made of the stoicheiometry of proton translocation coupled to respiration in mitochondria from Candida utilis where the number of functional energy-conservation sites between intramitochondrial NADH and oxygen was one in a mutant with a novel oxidase (Downie & Garland, 1972), two in sulphate-deficient cells (Haddock & Garland, 1971) or three in glycerol-limited cells (Light & Garland, 1971). The stoicheiometries of protons translocated per atom of oxygen utilized (i.e. -->H(+)/2e(-) ratio; Mitchell, 1966) were close to 2.0, 4.0 and 6.0 respectively. Thus by using the same substrate (intramitochondrial NADH) and oxygen throughout, the -->H(+)/2e(-) ratio is shown to be 2.0 per energy-conservation site when the number of such sites is varied from one to three.     

Identification of a rhizosphere protein encoded by the symbiotic plasmid of Rhizobium leguminosarum.

A protein was identified which was made by wild-type strains of Rhizobium leguminosarum but not by nodulation-deficient derivatives which had deletions of their symbiotic plasmids. The protein, which had a subunit molecular weight of ca. 24,000 ( 24K ), was found to be present in large amounts within bacteria that had been reisolated from the surface of inoculated pea roots but was not detected in bacteroids isolated from nodules. The protein could also be induced during growth of R. leguminosarum on nutrient medium and was purified from the cytoplasmic fraction of broken cells. Antiserum raised against the purified protein was used to screen transposon-induced mutants of R. leguminosarum, and four independent mutants were isolated which lacked the protein. The sites of the Tn5 insertions were found to map between the nitrogenase and nodulation genes on symbiotic plasmid pRL1JI , ca. 5 kilobases from the nitrogenase genes and 13 kilobases from the nodulation genes. Genetic determinants for the 24K protein were found to be closely linked to plasmid-borne nodulation genes for all strains of R. leguminosarum tested. However, the mutants which lacked the 24K protein still formed normal nitrogen-fixing nodules on peas, and the function of the protein is unknown.