Biomedical subjects
A Taylor
Publications and source records attributed to A Taylor.
Bone scanning in the diagnosis of acute osteomyelitis.
Fifty-nine patients with suspected osteomyelitis were referred to the Nuclear Medicine Service for bone scanning during a twelve month period. The bone scan correctly identified abnormal sites in 18 of 19 patients with osteomyelitis (sensitivity of 95%) while the radiograph detected only 6 of 19 (sensitivity of 32%). In this clinical setting, the bone scans and radiographs had specificities of 92% and 89% respectively. Technetium-99m phosphate radiopharmaceuticals are superior to the previously used isotopes of fluorine and strontium in that they are readily available, can be imaged with conventional instruments, and allow high quality scans to be completed within 4 h. Routine bone scanning should be performed in patients presenting with suspected osteomyelitis and normal radiographs. The scan can be helpful in confirming or excluding the clinical suspicion and can lead to a more rapid institution of appropriate treatment.
Specific response of Escherichia coli K12 sfiA mutants to the presence of ethyl ester of N-alpha-palmitoyl-L-lysyl-L-lysine dihydrochloride (PLL) in a nutrient medium.
N-alpha-palmitoyl-L-lysyl-L-lysine dihydrochloride ethyl ester (PLL) in sublethal doses (6--12.5 microgram/ml) inhibits cell division in E. coli K12 strains C600, JM1, and derivatives of JM1 carrying mutations tif-1, tif-1, sfiA, tif-1 sfiB and sfiB in conditions which do not induces SOS functions. Only sfiA mutants divide normally in the presence of PLL. This response enables direct discrimination between phenotypes of sfiA and sfiB and moreover, also the selection of spontaneous mutants sfiA in a tif+ (recA+) genetic background. The PLL mediated inhibition of cell division in tif-1 sfiA double mutants may indicate that the recA gene product plays a role in the restoration of cell division by sfiA.
Murein transglycosylase from phage lambda lysate. Purification and properties.
Lysates of induced E. coli (lambda) lysogens contain two enzymes acting on murein: endopeptidase and murein transglycosylase. The transglycosylase was separated from the endopeptidase and purified to homogeneity. Its bacteriolytic activity was 200-fold higher than of hen egg lysozyme. The bacteriolytic activity of the lysate depends on the presence of the enzyme. The endopeptidase alone not lyse the cells, but it enhances the extent of lysis. The properties of the transglycosylase (molecular weight 17 500, pH optimum at 6.6, inactivation by Zn2+), show that it is entirely different from the bacterial enzyme of the same specificity described by others. Data are presented, which suggest that this enzyme is the phage lambda R-gene product.
Unwinding and rewinding of DNA by the RecBC enzyme.
Under physiological conditions the initial action of the RecBC enzyme (exonuclease V) on duplex DNA is unwinding of the DNA strands. We have examined by electron microscopy the initial products of this unwinding reaction. When such reactions are carried out in the presence of DNA binding protein, unwinding structures are seen both at the terminus of the duplex DNA and at locations remote from the ends of the DNA molecule. Both terminal and internal unwinding structures proceed along DNA at about 300 nucleotides per second, and the single-stranded loops in both types of structure enlarge at about 100 nucleotides per second. In the internal unwindings DNA must be rewound behind the enzyme at about 200 nucleotides per second. The structures do not occur on supercoiled or nicked circular DNA, indicating that free ends are needed for their formation. In the absence of DNA binding protein only internal unwinding structures are seen, suggesting that the internal structures are formed from the terminal unwindings by base-pairing of their unwound single-strand tails. We present a model which incorporates these structures and is consistent with previous observations on the unwinding and degradative actions of the enzyme. In this model the enzyme travels through duplex DNA by unwinding the DNA ahead of itself and rewinding it behind itself. The internal unwindings produced by the RecBC enzyme could be active in initial synapsis step in genetic recombination.
Fusimotor activity in masseter nerve of the cat during reflex jaw movements.
1. Unit recordings have been made from the central ends of filaments of the masseter nerve in lightly anaesthetized cats. Evidence is presented to show that fusimotor activity may be distinguished from alpha motor activity. 2. During reflex cyclic movements induced by intra-oral stimulation, two distinct patterns of fusimotor firing emerged. One type of unit increased firing at the beginning and sustained this with little modulation throughout the movements. The other type was strongly modulated approximately in parallel with the alpha motor activity. 3. By comparison with records of jaw elevator spindle afferents under similar conditions, it was deduced that the sustained type of action was due to dynamic fusimotor neurones while the modulated type was due to static fusimotor neurones. 4. The patterns of fusimotor activity seen in these rhythmic movements under light anaesthesia agree well with the patterns deduced from spindle recordings in the conscious cat during mastication. 5. The results emphasize the importance of looking beyond a simple hypothesis of 'alpha-gamma co-activation' to explain fusimotor function. It is proposed that tonic dynamic fusimotor activity is set at the beginning of a movement to determine the incremental sensitivity of primary endings to stretch. The static fusimotor fibres are activated principally during shortening to help keep both primary and secondary endings active.
Immunochemical properties of Vi antigen from Salmonella typhi Ty2: presence of two antigenic determinants.
Antigen Vi of Salmonella typhi was found to have at least two antigenic determinants. In one of them, O-acetyl moiety played a dominant role. The second antigenic determinant did not involve O-acetyl residues, but both carboxyl and N-acetyl groups were necessary for the antigen-antibody reaction. These results were obtained by performing serological tests with antigen Vi, with its structural analog, polygalacturonic acid, and with the derivatives of both polysaccharides.
Diversity of Vi-related antigens in the microcapsule of Salmonella typhi.
Two new antigenic acidic polysaccharides, Vi-P and Vi-C, were isolated from the microcapsule of Salmonella typhi by a very mild procedure. The antigens were purified to serological homogeneity, and it was found that each of them shares with Vi antigen one of its two serological determinants (a different one in each case). One of the antigens Vi-C, was also isolated from Escherichia coli B, which is not a Vi-producing strain.
Delayed scanning with DMSA: a simple index of relative renal plasma flow.
Relative renal uptake of 99mTc-dimercaptosuccinic acid (DMSA) was compared with the relative effective renal plasma flow (ERPF) to each kidney. In 25 patients with serum creatinine less than or equal to 2.0 mg/dl, there was excellent agreement when the regions of interest were assigned by a computer. In 10 patients with serum creatinine greater than 2.0 mg/dl, agreement was poor. A 24-hour image is sufficient to obtain such data. In patients with renal failure, this technique may give inaccurate results due to high tissue background activity; moreover, since it reflects the current functioning status of the kidney, it should not be used to predict recoverable function in patients with acute or unstable renal disease.
Saliva from patients with cystic fibrosis inhibits amiloride-sensitive sodium transport.
A factor is present in the saliva and sweat from patients with cystic fibrosis (CF) which inhibits the reabsorption of sodium in the ducts of the salivary and sweat glands. Inasmuch as the physiology of sodium absorption is similar in salivary ducts and the distal colon, we have examined the sensitivity of the sodium absorption in the rat colon to saliva from CF patients. Sodium absorption by the rat colon, estimated as the shortcircuit current, was inhibited by saliva from both patients with CF and normal volunteers. However, only with CF saliva was the inhibition consistently proportional to the saliva concentration. Furthermore, the inhibitory activity of CF saliva was greater than the inhibition observed with saliva from age- and sex-matched controls (percentage of inhibition: CF = 20.1 +/- 2.2, and controls = 14.9 +/- 2.1; P < 0.02), and the inhibition of the colonic shortcircuit current was proportional to the activity measured by the ductal retrograde perfusion assay with the rat parotid gland (linear correlation coefficient = 0.634; P < 0.005). This latter assay is an accepted assay for CF factor activity. We conclude that the CF factor present in saliva probably interacts in a reversible manner with the amiloride-sensitive sodium transport system which is present in all sodium scavenging epithelia. The rat colon is a promising assay system for CF factor activity because the electrical measurements permit a rapid quantitative estimate of activity and a single piece of tissue can be used to measure the activity of several saliva samples.
Optimal handling of dimercaptosuccinic acid for quantitative renal scanning.
Methods of optimizing quantitative renal imaging with Tc-99m dimercaptosuccinic acid (DSMA) were investigated. Rats were injected with DMSA (one kit per rat) and sacrificed at 0.5, 2.0, and 24 hr after injection. Fifty percent of the injected dose localized in the kidneys at 0.5, 2, and 24 hr after injection while background activity peaked at 0.5 hr and then declined to give substantially higher kidney-to-background ratios at 24 hr. Delayed scanning should increase the accuracy of clinical studies in patients with low kidney-to-background ratios at 1-2 hr. After injection of DMSA, 1 ml of air was introduced into the reaction vials and incubated 20 min. Kidney uptake decreased from 50 to 40% and liver uptake increased from 7.5 to 17%. If multiple doses must be drawn from a single vial, air should not be introduced, and the doses should be drawn together and administered immediately to minimize radiopharmaceutical deterioration.
Improving the effectiveness of generic outcome screening criteria.
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Renal gallium accumulation in rats with antibiotic-induced nephritis: clinical implications. Concise communication.
To determine the effect of antibiotic-induced nephrotoxicity on the renal accumulation of gallium, groups of ten Sprague-Dawley rats were given intraperitoneal injections of gentamycin, amphotericin, or neomycin for a period of 16--21 days. In all cases, mild to moderate nephrotoxicity was documented by one or more of the following parameters: serum creatinine, renal weight, urine volume (renal concentrating ability), light microscopy, and electron microscopy. In none of these cases was the renal accumulation of gallium increased over control values. Consequently, diffuse renal accumulation of gallium in patients with subclinical or mild nephrotoxicity is unlikely to be related to short-term treatment with aminoglycosides or amphotericin. In such cases, the physician should seek some other clinical explanation, such as infection.
Nabilone as an antiemetic.
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Intoxication of normal and virus-transformed cells by diphtheria toxin.
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Low-molecular-weight substrate for the lysozyme of T4 bacteriophage.
It has been shown that muropeptide CB, the chemically defined product of Escherichia coli B murein digestion by phage lambda endolysin, is the substrate for T4 lysozyme. This is the tetrasaccharide GlcNAc-MurNAc-GlcNAc-anMurNAc in which the carboxyl groups of MurNAc and anMurNAc residues are substituted by tetrapeptide LAla-DGlu-msA2pm-DAla (MurNAc = N-acetylmuramic acid, GlcNAc = N-acetyl-D-glucosamine, anMurNAc = 1,6-anhydro-N-acetylmuramic acid, LAla = L-alanine, DGlu = D-glutamic acid, msA2pm = meso-diaminopimelic acid). The substrate contains one bond hydrolysable by T4 lysozyme. The products of hydrolysis are the easily identifiable disaccharide muropeptides C6 (GlcNAc-MurNAc-LAla-DGlu-msA2pm-DAla) and CA (GlcNAc-anMurNac-LAla-DGlu-msA2pm-DAla). Thus the substrate may be used for the specific identification of murein N-acetylmuramoylhydrolases of the T4 lysozyme type, as well as for any quantitative measurement of the enzymatic reaction.
Leucine aminopeptidase (bovine lens): an electron microscopic study.
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The group psychotherapy literature: 1978.
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