Activity of crystalline turkey egg white lysozyme

Hexagonal crystals of turkey egg white lysozyme have been examined for activity in order to evaluate their potential for use in time-resolved X-ray crystallographic experiments. Substrates used in this study were hexa-N-acetylglucosamine (hexa-GlcNAc) and a modified analogue of hexa-GlcNAc where the terminal sugar ring was opened by reduction with tritiated sodium borohydride. This gave a labeled beta-N-acetylglucosaminitol unit at the sixth position of the sugar chain and allowed easy quantitation of enzymatic cleavage on TLC plates. Using these substrates, it has been shown that turkey egg white lysozyme is enzymatically active in the crystal. Enzyme dispersed in the buffer surrounding the crystal does not show detectable activity under conditions relevant to an X-ray experiment. Unmodified hexa-GlcNAc is hydrolyzed into di-, tri-, and tetrasaccharides in the crystal. This cleavage pattern is different from that obtained with hen egg white lysozyme in solution and likely causes of the differences are discussed. The reduced radiolabeled oligosaccharide has a unique cleavage pattern with trisaccharides as the products. The specific activity of the enzyme with the radiolabelled analogue was 9.8 (+/- 1.0) x 10(-7) mmol/min/mg protein at 22 degrees C in the crystal.

Helicopter doctors?

All roadside procedures carried out by doctors of the Royal London Hospital Helicopter Emergency Medical Service were recorded. Of 100 injured patients treated consecutively, 68 patients required 73 treatments or procedures that were beyond the current training of the ambulance paramedic in the United Kingdom. Doctors are therefore an essential part of HEMS operations and allow earlier live-saving medical intervention in the prehospital phase of care.

4-Quinolone-resistant Neisseria gonorrhoeae in the United Kingdom

The auxotype, serogroup and antimicrobial susceptibility of 977 clinical isolates of Neisseria gonorrhoeae obtained at St Thomas' Hospital, London, during 1989 were determined; 23 isolates from 15 patients were resistant to 4-quinolones. Twelve of the patients acquired their infection in the UK and these strains were generally sensitive to other antimicrobial agents; strains from 10 patients were of serogroup IB-6. Three patients acquired their strains outside the UK and these isolates were multi-resistant and of different serogroups.

Temperature-dependent hysteresis in somatosensory and auditory evoked potentials

Fourteen adult patients undergoing open heart surgery under induced hypothermia had median nerve, short-latency somatosensory evoked potentials (SSEPs) recorded during cooling (from 36 degrees C to 19 degrees C) and subsequent rewarming. Similar data on another group of patients who had brain-stem auditory evoked potentials (BAEPs) were also analyzed. Hypothermia produced increased latencies of the major SSEP and BAEP components and the latencies returned to normal with subsequent warming. The temperature-latency relationship during the cooling phase was significantly different from that during the warming phase. For SSEP components the temperature-latency relationship was linear during cooling and curvilinear during warming, whereas for BAEP it was curvilinear both during cooling and warming. Furthermore, the regression curves were different during the two phases of temperature manipulation, particularly for temperatures below 30 degrees C both for SSEP and BAEP components. At the onset of warming there was an initial exaggerated warming response on the evoked potential (EP) latencies and amplitude of the EP components. The temperature-latency regression curves were uniformly less steep during the warming phase compared to those during cooling. These findings suggest the existence of hysteresis in the relationship between temperature and EP latencies. The latencies at a given temperature below 30 degrees C depend on whether that temperature is reached during cooling or during warming.

Effects of hypothermia on short latency somatosensory evoked potentials in humans

Short latency somatosensory evoked potentials (SSEPs) elicited by median nerve stimulation were monitored in 14 adult patients undergoing cardiac surgery under cardiopulmonary bypass and induced hypothermia. SSEPs were recorded at 1-2 degrees C steps as the body temperature was lowered from 37 degrees C to 20 degrees C to determine temperature-dependent changes. Hypothermia produced increased latencies of the peaks of N10, P14 and N19 components, the prolongation was more severe for the later components so that N10-P14 and P14-N19 interpeak latencies were also prolonged. The temperature-latency relationship had a linear correlation. The magnitude of latency prolongation (msec) with 1 degree C decline in temperature was 0.61, 1.15, 1.56 for N10, P14 and N19 components, respectively, and 0.39 and 0.68 for interpeak latencies N10-P14 and P14-N19, respectively. The rise time and duration of the 3 SSEP components increased progressively with cooling. Cortically generated component, N19, was consistently recordable at a temperature above 26 degrees C, usually disappearing between 20 degrees C and 25 degrees C. On the other hand, more peripherally generated components, N10 and P14, were more resistant to the effect of hypothermia; P14 was always elicitable at 21 degrees C or above, whereas N10 persisted even below 20 degrees C. The amplitude of SSEP components had a poor correlation with temperature; there was a slight tendency for N10 and P14 to increase and for N19 to decrease with declining temperature. Because incidental hypothermia is common in comatose and anesthetized patients, temperature-related changes must be taken into consideration during SSEP monitoring under these circumstances.

Developmental and genetic aspects of Mutator excision in maize

The regulation of excision of Mu elements of the Mutator transposable element family of maize is not well understood. We have used somatic instability of Mu receptor elements from the Bronze 1 and Bronze 2 loci to monitor the frequency and the timing of excision of Mu elements in several tissues. We show that spot size in the aleurone of a bz2::mu1 stock varies between one to approximately 256 cells. This indicates that excision events begin eight divisions prior to full aleurone differentiation and end after the last division of the aleurone. We show that excision is equally biased for late events in all other tissues studied. A locus on chromosome 5 has been identified that affects spot size, possibly by altering the timing of Mu excision. Using somatic excision as an assay of Mutator activity, we found that activity can change in small sectors of the tassel; however, there are no overall activity changes in the tassel during the period of pollen shedding. We also report the recovery of germinal revertants for the bz1::mu1 and bz2::mu1 alleles. One of these revertant alleles was characterized by Southern blot analysis and found to be similar to the progenitor of the mutable allele.

Psychological effects of dieting

Seven men and seven women, all of normal weight, were assessed by means of daily visual analogue scales for a two-week baseline period and for two weeks during which they were placed on a calorie-restricted diet. There were no significant changes in mood and no sex differences. Compared with the baseline, during the diet there were significant changes in their cognitions concerning eating: subjects were more preoccupied with thoughts about food, had strong urges to eat more frequently and were more likely to feel out of control of their eating.

Polymorphous low-grade adenocarcinoma of minor salivary gland. An immunohistochemical and clinicopathologic study

Polymorphous low-grade adenocarcinoma (PLGA) is a minor salivary gland carcinoma usually arising intraorally, primarily in the palate. It is characterized by cytologic uniformity, histologic blandness, and a variable, infiltrating growth pattern. To date, 117 tumors have been reported but the immunohistochemical features of this neoplasm have not been adequately described. This report describes the immunohistochemical distribution of epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), high-molecular-weight keratin, muscle-specific actin (MSA), and S-100 protein in four palatal polymorphous low-grade adenocarcinomas arising in two men and two women. Three patients were treated with a combination of radiation and surgery, and one was treated with just surgery; none of the tumors recurred or metastasized. More than 90% of tumor cells in all four tumors stained with S-100 and EMA, while 75 to 95% stained with keratin. MSA staining intensity was variable; it ranged from less than 10% to 67% of tumor cells staining positively. CEA staining also was markedly variable; it ranged from very focal luminal positivity to 75% of tumor cells staining positive. The diffuse staining pattern of EMA and S-100 and the difference in staining patterns of EMA and CEA in PLGA is distinct from that found in adenoid cystic carcinoma. In the latter neoplasm, EMA and CEA staining patterns are similar and they are localized to ductal lumina; S-100 stains much less diffusely. These differences are useful in the differential diagnosis between these two tumors.

Regulation of mutator activities in maize

We discuss the properties of the Mutator (Mu) transposable element family of maize. We report the cloning of bz2-mu1, a mutable allele containing a 1.4-kb Mu element, using a combination of transposon tagging and tests for differential hybridization to northern and Southern blots. We report the sequence of this allele and the Mu element insertion, and propose a model for the structure of the Bz2 locus. We discuss the relationship between increased DNA modification of Mu elements and loss of somatic instability at bz2-mu1. To further explore this aspect of regulation of Mutator, we have used gene-specific probes to determine the level of modification at this locus in active and inactive Mutator lines. We have also utilized CsCl density gradients to estimate the overall level of DNA modification in active and inactive lines; we find that Mu elements in active lines are hypomethylated relative to other maize nuclear DNAs examined, and that in inactive lines the level of modification in Mu elements is similar to the genome as a whole. Utilizing gamma-irradiation, we have demonstrated that inactive lines can be reactivated; this reactivation is first noted as restitution of the spotted kernel phenotype characteristic of bz2-mu1 in active Mutator lines. Hybridization analysis of DNA from reactivated plants demonstrates that the Mu elements in general, and specifically the Mu element at bz2-mu1, have the lower level of DNA modification characteristic of active lines. These results are discussed in terms of the role and timing of DNA modification in regulating Mutator activities.

Regulation of Mu element copy number in maize lines with an active or inactive Mutator transposable element system

In the progeny of an active Mutator plant, the number of Mu elements increases on self-pollination and maintains the average parental Mu content on outcrossing to a non-Mutator line; both patterns of transmission require an increase in the absolute number of Mu elements from one generation to the next. The same average copy number of Mu elements is transmitted through the male and female, but there is wide variation in the absolute copy number among the progeny. In inactive Mutator plants-defined both by the loss of somatic instability at a reporter gene (bronze2-mu1) and by modification of the HinfI sites in the terminal inverted repeat sequences of Mu elements - the absolute copy number of Mu elements is fixed in the parent. Thus, in outcrosses Mu element number is halved, and on self-pollination Mu copy number is constant. Reactivation of somatic mutability at cryptic bz2-mu1 alleles in inactive individuals by crossing to an active line seems not to involve an increase in Mu element copy number transmitted by the inactive individual. These and other results suggest that increases in Mu copy number occur late in plant development or in the gametophyte rather than after fertilization.

Oral cholecystography and sonography of gallbladder in cholecystectomy patients

In comparing the diagnostic specificity and sensitivity of oral cholecystography with that of sonography in 479 patients in a community hospital, the oral cholecystogram, when used with a double dose of contrast agent, showed greater specificity (1.00) and sensitivity (0.99) than the sonogram (0.54 and 0.94, respectively). Because of lower cost, the oral cholecystogram should be used as the initial diagnostic study when cholelithiasis is suspected, unless specific contraindications exist.

Effects of hypothermia on brainstem auditory evoked potentials in humans

Ten adult patients who underwent open heart surgery under induced hypothermia had brainstem auditory evoked potentials (BAEPs) recorded at 1 degree- to 2 degrees C-steps as body temperature was lowered from 36 degrees C to 20 degrees C to determine temperature-dependent changes. Hypothermia produced increased latencies of BAEP waves I, III, and V; the prolongation was more severe for the later components with the result that interpeak latencies I-III, III-V, and I-V were also prolonged. The temperature-latency relationship was nonlinear and best expressed by exponential curve. The latencies of waves I, III, V and the interpeak latency I-V increased roughly 7% for each 1 degree C drop; they doubled at a temperature around 26 degrees C. The amplitude of the BAEP components had a quasiparabolic relationship to temperature; the amplitude rose with hypothermia to 28 degrees or 27 degrees C, but decreased linearly with further cooling. All BAEP components were present at temperatures above 23 degrees C and absent below 20 degrees C. With rewarming, the changes reversed and BAEPs returned to initial prehypothermia status.

Serum hyaluronic acid in patients with disseminated neoplasm

Hyaluronic acid concentrations were measured by a laser nephelometric assay in serum samples from 50 patients with advanced disseminated neoplasm and 50 healthy controls matched for age and sex. The identity of hyaluronic acid was confirmed by a combination of electrophoretic and enzymatic techniques. The mean serum hyaluronic acid concentration for the control group was 1.09 mg/l, with a range of 0-4 mg/l. The mean concentration for patients with neoplastic disease was 10.38 mg/l, with a range of 0-100 mg/l. Sixty two per cent of the patients with disseminated neoplasm had serum hyaluronic acid concentrations above the control range. There was no correlation between the increased concentration of hyaluronic acid and tumour type, serum bilirubin, serum alkaline phosphatase, or serum urea concentrations. There was a higher incidence of hypercalcaemia in patients with increased hyaluronic acid concentrations, but the correlation between hyaluronic acid and calcium concentrations was not significant. In view of the possible role of hyaluronic acid in cellular differentiation and morphogenesis the finding of increased hyaluronic acid concentrations in patients with advanced neoplastic disease may be of fundamental importance in cancer biology.

Macrolide, lincosamide and streptogramin resistance in Campylobacter jejuni/coli

Strains of erythromycin-resistant Campylobacter jejuni/coli isolated in the United Kingdom, Canada and Europe, were also resistant to tylosin, spiramycin and clindamycin and, like sensitive strains, were insensitive to virginiamycin and pristinamycin component B. These were designated as macrolide-lincosamide-streptogramin generalized resistant organisms and macrolide-lincosamide generalized resistant on the basis of patterns of resistance to pristinamycin components A and B. Two erythromycin-sensitive strains whose resistance to spiramycin and tylosin had been produced in the laboratory showed cross resistance to erythromycin, but were still sensitive to clindamycin. These were characterized as macrolide-streptogramin A inducible resistant organisms. The isolates tested were identified and all were found to be C. coli, except for two strains, one erythromycin-resistant and one erythromycin-sensitive, which hydrolyzed hippurate and were thus identified as C. jejuni.

A comparison of the homogeneous enzyme immunoassay (EMIT) autocarousel and quantitative single test (QST) systems with the radioenzymatic assay

A comparison was made of three methods for gentamicin assay; a modification of the radioenzymatic transferase technique, which was used as the reference method; EMIT autocarousel; and EMIT quantitative single test (QST). Correlation of both EMIT systems with the radioenzymatic method and with each other gave acceptable correlation coefficients, 0.955-0.975, for the range of concentrations tested. The coefficients of variation for within assay studies were between 3.3 and 4.9 for all three methods. Both EMIT systems provided rapid results, within minutes, albeit at a higher cost than the radioenzymatic assay. The radioenzymatic technique although cheaper with regard to the cost of materials involves considerably more technical time and effort and might not be considered suitable for samples received out-of-hours. However the combination of both EMIT systems provides facilities for batch and one-off sample tests and the ease of operation and rapid results are suited to out-of-hours operation.

Monitoring of somatosensory evoked responses during carotid endarterectomy

During carotid endarterectomy (CEA), we monitored somatosensory evoked responses (SERs) ipsilaterally over the scalp following stimulation of the contralateral median nerve at the wrist. Thirty-eight CEAs in 36 patients were studied. Of the 10 CEAs performed with patients under general anesthesia, three involved marked changes in SERs, reversed by shunt insertion. The remaining 28 CEAs were done with patients under local anesthesia. The SERs remained stable during an average clamp time of 30 minutes in all except one patient, in whom SER changes developed within a minute of clamping; the changes were reversed by shunt placement. Four of the 38 CEAs required a shunt based on SER changes, although measurement of stump pressure (less than 50 mm Hg) would have indicated the necessity of a shunt in eight additional operations. We concluded that SERs are useful in signaling cerebral ischemia and the need for a shunt during CEA.

Evoked response studies in patients with adrenoleukodystrophy and heterozygous relatives

Brain-stem auditory evoked responses (BAERs) and somatosensory evoked responses (SERs) were studied in three patients and seven female relatives in three families with adrenoleukodystrophy (ALD). All patients with ALD had abnormal BAERs and SERs, reflecting the central demyelination occurring in ALD. Four of the seven female family members had abnormalities of SERs with or without abnormalities of BAERs, similar to those seen in the patients. We suggest that these abnormalities demonstrate the morphological effects of the ALD gene in the CNS and reflect the physiological alteration in the heterozygous females in families with ALD.

Cefotetan: in-vitro antibacterial activity and susceptibility to beta-lactamases

The in-vitro antibacterial activity of cefotetan was assessed against recent clinical isolates of common bacteria and also against reference strains that produced known beta-lactamases. The compound was active against most staphylococci (MICs 4 to 8 mg/l) though methicillin-resistant strains were less sensitive. It was also generally active against streptococci (MICs mostly in the range 1 to 16 mg/l). However, enterococci and penicillin-resistant pneumococci were resistant. Cefotetan was highly active against enterobacteria, with 75% of isolates inhibited by 0.5 mg/l and 90% inhibited by 4 mg/l. It was also highly active against Haemophilus influenzae (MICs 0.5 to 4 mg/l) and Neisseria gonorrhoeae (MICs 0.06 to 2 mg/l) but had relatively poor activity against Acinetobacter spp. (MICs mostly 4 to 128 mg/l). Cefotetan had little useful activity against Pseudomonas aeruginosa (MICs 16 to 512 mg/l) but was more active against most other pseudomonads. Cefotetan had moderate activity against the Bacteroides fragilis group (MICs mostly less than or equal to 32 mg/l), though Bact. fragilis sensu stricto and Bact. vulgatus were more sensitive (MICs usually less than or equal to 4 mg/l). It was more active against most other anaerobes, though its activity was always exceeded by that of ampicillin. Cefotetan possessed a high degree of resistance to both plasmid-mediated and chromosomally-determined beta-lactamases.

Brain stem auditory, visual and somatosensory evoked potentials in leukodystrophies

Brain stem auditory (BAERs), visual (VEPs) and somatosensory evoked responses (SEPs) were recorded in 12 patients with Pelizaeus-Merzbacher leukodystrophy (PMD), three with adrenoleukodystrophy (ALD) and three with metachromatic leukodystrophy (MLD). All the 3 evoked responses were abnormal in all patients except normal VEPs and SEPs in a patient with early ALD. In most patients wave I with and without wave II were the only components of the BAERs that remained, subsequent components (waves III-VII) were absent. VEPs were severely altered; either no identifiable response to flash or pattern reversal stimuli could be recorded or the major components were significantly delayed in latency. Short latency SEPs following median nerve stimulation usually showed a normally recorded Erb's potential (N10), but an absence or marked attenuation of cervical (N14) and early scalp components (N19 and P22) or the occurrence of the scalp components with a significant delay. Multimodality evoked responses provide more information regarding the functional integrity of several afferent systems in patients with white matter disorders.

Immune complexes in early arthritis. II. Immune complex constituents are synthesized in the synovium before rheumatoid factors

Synovial fluids and paired sera taken from patients either before, after or at the time of diagnosis of definite rheumatoid arthritis (RA) were compared with samples from patients with unclassified inflammatory arthropathies (IA). Raised levels of immune complexes (IC) were detected in some RA patients by C1q binding activity but in the majority of both RA and IA patients by the platelet aggregation test; levels were usually higher in joint fluids than in sera. IgM rheumatoid factors (RF) and IgA RFs were lower in synovial fluids but IgF RF levels were similar in matched samples. Synovial fluid to serum albumin ratios were used to estimate synovial permeability (inflammation) and then to calculate which patients synthesized macromolecules locally in the synovium. Local synthesis of RFs was detected in a greater proportion of RA than IA patients and only two patients formed RFs locally in the first months of symptoms. Half the patients in both groups however appeared to synthesize or trap IC constituents and in many patients there was evidence of local synthesis within 6 months after their symptoms had started. We conclude that local synthesis of large amounts of RFs is uncommon in the early stages of RA but that IC of unknown composition are synthesized or localized in the affected joints of many patients with RA and inflammatory arthropathies shortly after their symptoms appear.

In vitro antibacterial activity of norfloxacin (MK-0366)

The in vitro activity of norfloxacin (MK-0366) compared with that of beta-lactam antibiotics and, where appropriate of gentamicin or metronidazole was assessed against recent clinical isolates of common bacteria. The compound was highly active against most enterobacteria (minimal inhibitory concentrations [MICs], 0.008 to 32 micrograms/ml; 90% inhibited by 0.25 micrograms/ml), Haemophilus influenzae (MICs, 0.03 to 0.12 micrograms/ml), and Neisseria gonorrhoeae (MICs, 0.008 to 0.016 micrograms/ml). It was also active against Pseudomonas aeruginosa (MICs, 0.12 to 2 micrograms/ml), most other pseudomonads (MICs, 0.03 to 32 micrograms/ml), and Acinetobacter calcoaceticus (MICs 0.06 to 4 micrograms/ml). Norfloxacin was somewhat less active against staphylococci (MICs, 0.25 to 4 micrograms/ml; 1 microgram/ml required to inhibit 50% of isolates) and streptococci (MICs, 0.5 to 64 micrograms/ml). Members of the Bacteroides fragilis group of anaerobes were relatively resistant to norfloxacin (MICs, 8 to 128 micrograms/ml), as were most other anaerobes.

Serum concanavalin-A binding in rheumatoid arthritis

A nephelometric assay of concanavalin-A binding of serum acute phase proteins (con-A binding) has been used in cross-sectional and sequential studies of disease activity in rheumatoid arthritis (RA). Con-A binding correlated well with blood viscosity, C-reactive protein, and other individual acute phase reactants in patients with active RA. Twenty-four patients were treated for 6 months with D-penicillamine and assessed clinically and seriologically. Clinical improvement was accompanied by significant falls in both C-reactive protein and con-A binding, although the serological changes did not always occur in parallel in individual patients. The advantages of this simple, cheap assay of acute phase proteins are discussed.

The effects of priming on picture recognition

In two experiments we show that the prior presentation of a picture serves to facilitate the recognition of that picture in a tachistoscope up to 45 minutes later. Facilitation of recognition also occurred with prior presentation of a different picture with the same name. This cannot be explained items of a response bias, since the presentation of a word, which the subject read aloud, had no effect whatsoever upon the subsequent recognition of the picture. The data are interpreted in terms of a categorization stage for pictures which is completely independent of the verbal system. Data from other experimental paradigms are also examined. Our categorization model enables consistent interpretation of these data, which otherwise appear contradictory.

Measurement of serum glycosaminoglycans by laser nephelometry

A simple, sensitive micromethod for the assay of serum hyaluronic acid and chondroitin sulphates is presented. The method is based on the binding of the quaternary ammonium salt, cetylpyridinium chloride (CPC) to serum polyanions, and quantitation of the complexes by laser nephelometry. Measurement of the CPC complexes in serum before and after digestion with specific enzymes enables quantitation of hyaluronic acid and chondroitin sulphates in less than 100 microliters serum. Using this technique, hyaluronic acid is detectable in a small number of normal human sera at concentrations up to 4 mg/l, and chondroitin sulphates are consistently present at concentrations ranging from 2 to 25 mg/l.

In vitro antibacterial activity and susceptibility of the cephalosporin Ro 13-9904 to beta-lactamases

The in vitro activity of Ro 13-9904 was assessed against clinical isolated of common bacteria. Its activity against most enterobacteria was similar to that of cefotaxime and moxalactam, but it was even more active than these compounds against all Proteus species. It was also highly active against Haemophilus influenzae and Neisseria gonorrhoeae, including beta-lactamase producers. Like cefotaxime and moxalactam, Or 13-9904 was approximately eightfold more active than carbenicillin against most isolates of Pseudomonas aeruginosa and also active against highly carbenicillin-resistant isolates, but it was relatively inactive against moderately carbenicillin-resistant isolates. Ro 13-9904 also resembled cefotaxime and moxalactam in that it was active, though less so than cephaloridine, against staphylococci and streptococci, except for methicillin-resistant staphylococci and Streptococcus faecalis, which were resistant to it. It was less active than cefoxitin but slightly more active than ampicillin against both Bacteroides fragilis and other Bacteroides spp. Ro 13-9904 was resistant to most beta-lactamases but was attacked by enzymes from B. fragilis, isolates of indole-positive Proteus species, and also by a cefoxitin-hydrolyzing enzyme from an isolate of Enterobacter cloacae.