Human IgG preparations isolated by ion-exchange or protein G affinity chromatography differ in their glycosylation profiles

IgG from patients with rheumatoid arthritis (RA) is abnormally glycosylated in the Fc region, with sialic acid and galactose levels lower than normal. Protein G and DEAE purify populations which are differentially glycosylated. Significantly increased exposure of sialic acid was detected in normal IgG compared with that of RA IgG when ion exchange was used to prepare samples. However, when the same samples were prepared using protein G, no difference in the detection of sialic acid was seen between the two groups. When examining the heavy chain of IgG, more sialic acid, galactose and N-acetylglucosamine were detected in DEAE purified IgG compared with that prepared by protein G Detection of sialic acid and N-acetylglucosamine was also increased on light chains from IgG prepared by ion exchange chromatography. Since this occurs notably on rheumatoid light chains it would appear that this arrangement would contribute to the overall glycosylation changes in IgG. In the case of molecules lacking galactose the discrimination between the RA and normal IgG is significantly improved when ion exchange chromatography is used. Since differentiation between disease and normal groups relies on the purification technique used, we recommend that more than one method is employed before undertaking an analysis of glycosylation changes.

Analysis of the mitochondrial DNA of the somatic hybrids of Solanum brevidens and S. tuberosum using non-radioactive digoxigenin-labelled DNA probes

Mitochondrial (mt) DNAs of somatic hybrids obtained by electrical and chemical fusion of mesophyll protoplasts of S. brevidens and a dihaploid line of S. tuberosum PDH 40 were analysed by Southern hybridization using the digoxigenin-labelled mtDNA sequences nad5 or orf25. In the Southern analysis of the hybrid mtDNA probed with nad5, most of the 19 hybrids analyzed had an RFLP pattern similar, but not identical, to one of the parents, S. tuberosum, PDH40. Nineteen percent of the hybrids had most of the S. brevidens fragments. Five of the hybrids had an identical RFLP pattern to either one of the parents while another two hybrids had novel RFLP patterns. Similar results were obtained by Southern analysis with orf25. These results clearly show that mtDNA rearrangements had occurred at a high frequency in the somatic hybrids. There were no differences in the frequencies of rearrangements observed between the hybrids regenerated from chemical and electrical fusions.

Production of asymmetric hybrids between Solanum tuberosum and irradiated S. brevidens

Asymmetric somatic hybrids were obtained by fusion of Solanum tuberosum (PDH40) protoplasts with 300- or 500-Gy irradiated protoplasts of S. brevidens. These radiation doses were sufficient to prevent the growth of the S. brevidens protoplasts. Putative hybrids were selected on the basis of phenotype from regenerated shoots and identified with a S. brevidens-specific probe. From these, 31 asymmetric hybrids were confirmed by morphological characteristics, isoenzyme patterns and RFLP analysis. The morphology of the asymmetric hybrids was intermediate between that of S. tuberosum and symmetric hybrids of both species (obtained without irradiation treatment). Chromosome counts from 17 asymmetric hybrids showed that the chromosome number of the hybrids ranged from 31 to 64. The asymmetric hybrids probably had one or two genome complements (i.e. either 24 or 48 chromosomes) from S. tuberosum and 7-22 chromosomes from S. brevidens. There was no clear correlation between the radiation dose and the degree of elimination of the S. brevidens genome.

Gene rescue in plants by direct gene transfer of total genomic DNA into protoplasts

To study the possibility of gene rescue in plants by direct gene transfer we chose the Arabidopsis mutant GH50 as a source of donor DNA. GH50 is tolerant of chlorsulfuron, a herbicide of the sulfonylurea class. Tobacco protoplasts were cotransfected with genomic DNA and the plasmid pHP23 which confers kanamycin resistance. A high frequency of cointegration of the plasmid and the genomic DNA was expected, which would allow the tagging of the plant selectable trait with the plasmid DNA. After transfection by electroporation the protoplasts were cultivated on regeneration medium supplemented with either chlorsulfuron or kanamycin as a selective agent. Selection on kanamycin yielded resistant calluses at an absolute transformation frequency (ATF) of 0.8 x 10(-3). Selection on chlorsulfuron yielded resistant calluses at an ATF of 4.7 x 10(-6). When a selection on chlorsulfuron was subsequently applied to the kanamycin resistant calluses, 8% of them showed resistance to this herbicide. Southern analysis carried out on the herbicide resistant transformants detected the presence of the herbicide resistance gene of Arabidopsis into the genome of the transformed tobacco. Segregation analysis showed the presence of the resistance gene and the marker gene in the progeny of the five analysed transformants. 3 transformants showed evidence of genetic linkage between the two genes. In addition we show that using the same technique a kanamycin resistance gene from a transgenic tobacco could be transferred into sugar beet protoplasts at a frequency of 0.17% of the transformants.

Comparison of some arthropod toxins and toxin fragments as antagonists of excitatory amino acid-induced excitation of rat spinal neurones

Wasp and spider venom toxins, which block glutamatergic transmission at invertebrate neuromuscular junctions, have recently been shown to block transmission at glutamate-operated synapses in mammalian central nervous system. Using the technique of iontophoresis on spinal neurones in anaesthetised rats, we have compared the action of five arthropod toxins and two toxin fragments, on responses to excitatory amino acids including alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate, kainate and N-methyl-D-aspartate (NMDA). All toxins caused greater than 70% mean reduction of non-NMDA responses. Only argiotoxin636 significantly reduced responses to NMDA. This blockade, like that induced by philanthotoxin-433 and -343, was readily reversible whereas blockade induced by Joro Spider toxin or Nephila Spider toxin was less readily reversible. Neither 2,4-dihydroxyphenylacetate nor 2,4-dihydroxyphenylacetylasparagine blocked NMDA or non-NMDA responses. It appears, therefore that small structural differences in the polyamine part of these toxin molecules give rise to different activity profiles with respect to selectivity and reversibility.

Excitatory amino acids: new tools for old stories or pharmacological subtypes of glutamate receptors: electrophysiological studies

Although the N-methyl-D-aspartate (NMDA) subtype of L-glutamate receptor is well characterized, the significance of non-NMDA glutamate-sensitive binding sites is not well documented. In this study, a new tricyclic quinoxalinedione (NBQX) and an arthropod toxin (philanthotoxin) were shown to block responses of spinal neurones in vivo to kainate, quisqualate, and AMPA in parallel but had little effect on responses to NMDA. Philanthotoxin appeared to be a use-dependent antagonist consistent with a channel-blocking mode of action. On cortical wedges in vitro, however, NBQX proved to be a more potent antagonist of AMPA and quisqualate than of kainate (pA2 values of 7.1, 7.0, and 5.6, respectively) with no effect at 10 microM on responses to NMDA. These studies provide evidence that on cortical neurones, but not on spinal neurones. AMPA and kainate depolarize by pharmacologically different mechanisms.

Epitope mapping

The immune response to extrinsic and intrinsic antigens involves specific antigen receptors on T and B cells. The precise antigenic determinants, or epitopes, recognized by these receptors are discrete sequences within the native antigen. The ability to identify and manufacture key epitopes in the immune response has important implications for disease diagnosis and immunointervention. Consequently, increasingly sophisticated technologies are being applied to epitope mapping. This report from a recent workshop gives a balanced view of progress to date and the challenges ahead.

Performance of new criteria for right ventricular hypertrophy and myocardial infarction in patients with pulmonary hypertension due to cor pulmonale and mitral stenosis

Historically, electrocardiographic criteria for right ventricular (RV) hypertrophy has achieved high specificity but low sensitivity. Recently, however, Butler-Leggett et al. have introduced three criteria that attained a 66% sensitivity in a population with RV hypertrophy due to mitral stenosis while maintaining a 95% specificity in an extensive normal control group. Electrocardiographic diagnosis of RV hypertrophy is principally dependent on changes in the QRS complex that may be masked or mimicked by myocardial infarction (MI). This dilemma has been confirmed by documentation of the low specificity of both the Selvester QRS scoring system for MI size estimation (greater than 3 points) and its screening subset (greater than 0 points) in a pure mitral stenosis population. This study introduces the population characterized by RV hypertrophy due to cor pulmonale, which has a mean pulmonary arterial systolic pressure that is higher than the mean for the mitral stenosis population and consequently suggests more severe RV hypertrophy. When compared, the Butler-Leggett criteria for RV hypertrophy are more sensitive in the new population than in the mitral stenosis population (89% versus 60%) and the Selvester QRS scoring system is less specific (12% versus 60%). Three sequential steps are suggested for electrocardiographic analysis: (1) diagnosis of RV hypertrophy using the Butler-Leggett criteria, (2) diagnosis of MI using the Selvester screening criteria in those patients with step 1 negative, and (3) estimation of MI size using the complete Selvester scoring system in patients with step 1 negative and step 2 positive.

Rheumatoid factors and complex formation. The role of light-chain framework sequences and glycosylation

New information regarding rheumatoid factors (RFs) indicates that the RFs synthesized in synovium and lymphoid tissues of patients with rheumatoid arthritis (RA) are different from monoclonal and nonspecific RFs associated with other inflammatory states. The characteristics of RF associated with RA are as follows. They are of all Ig isotypes (not just IgM), indicating T-cell participation in antibody maturation. They have higher avidity for human IgG than for rabbit IgG. They use the human germline heavy-chain variable region (VH) gene VHIII more frequently than other VH genes, and light chains from multiple families. (In contrast, monoclonal RFs use predominantly VH1 and very commonly the V kappa IIIb germline gene HUMkv325). RA IgG is somatically mutated. (In contrast, monoclonal RFs use unmutated germline Ig genes). This suggests they are matured by stimulation either with specific antigens or other activation signals such as cytokines. They are abnormally glycosylated. In general, during periods of disease activity in adult and juvenile RA, a galactose is missing from the Fc of the IgG molecule, leaving an empty "pocket" between the C gamma 2 domains of heavy chains. The IgG RFs self-associate. This may result at least in part when galactose on the F(ab')2 portion of one IgG molecule fills the empty pocket in the Fc of another Ig molecule. Self-association forms immune complexes capable of fixing complement and probably of causing joint damage and vasculitis.

Resistance in Solanum brevidens to both potato virus Y and potato virus X may be associated with slow cell-to-cell spread

A series of experiments was carried out to investigate the nature of the resistance of the wild potato species, Solanum brevidens, to potato virus X (PVX) and potato virus Y (PVY). In vitro inoculation of leaf protoplasts of S. brevidens and the virus-susceptible dihaploid S. tuberosum genotype PDH40 with PVX or PVY using polyethylene glycol showed that protoplasts of both species were similar in susceptibility. However, examination of protoplasts prepared from the leaves of S. tuberosum and S. brevidens inoculated 2 to 5 weeks earlier showed that the percentage of PVX- and PVY-infected leaf cells of S. tuberosum were, respectively, 45- to 100-fold and about 1000-fold greater than the percentage of infected leaf cells of S. brevidens. These results suggest that resistance in S. brevidens to both PVX and PVY could be associated with slow cell-to-cell spread rather than with slow virus replication.

NMDA receptor antagonist effects of the stereoisomers of beta-cyclazocine in rats, in vivo and in vitro

(+)- and (-)-beta-cyclazocine were examined as NMDA receptor antagonists following bath application to rat cortical wedges in vitro and i.v. administration to rat spinal cord neurones in vivo. Both isomers were found to be selective NMDA antagonists with little effect on excitations evoked by quisqualate. In vitro, IC50 values for (-)- and (+)-beta-cyclazocine against responses to 40 microM NMDA were estimated at 0.51 and greater than 100 microM, respectively. In vivo, (-)-beta-cyclazocine 0.25 mg.kg-1 reduced NMDA-evoked excitations by 70%, an effect substantially greater than that produced by (+)-beta-cyclazocine 2.5 mg.kg-1. (-)-beta-cyclazocine is the most potent NMDA antagonist benzomorphan tested to date, being about twice as potent as (-)-alpha-cyclazocine in this respect. In addition, the separation in potency exhibited by the beta-cyclazocine enantiomers as NMDA antagonists is much greater than that reported previously for the stereoisomers of the alpha-series.

Plant regeneration from protoplasts of Solanum species with potential agricultural value (S. hjertingii, S. polyadenium, S. capsicibaccatum)

Protoplasts have been isolated from three tuber-bearing Solanum species, S. hjertingii, S. polyadenium and S. capsicibaccatum, that are sexually incompatible with S. tuberosum, but possess potentially useful characters. For isolating protoplasts from leaves of in vitro shoot cultures of S. hjertingii and S. capsicibaccatum growth was improved by including silver thiosulfate in the medium. However, for S. polyadenium, leaves of pot-grown plants were the best source for protoplasts. Following protoplast division and culture, plants were regenerated from protoplasts of each of the species. The pattern of chromosome variation in regenerants was similar to that observed for other diploid and tetraploid Solanum species. The results indicate that it should be possible to introduce the potentially useful germplasm from these wild species into somatic hybrids with S. tuberosum by protoplast fusion.

Philanthotoxin blocks quisqualate-, AMPA- and kainate-, but not NMDA-, induced excitation of rat brainstem neurones in vivo

1. The effect of electrophoretic ejection of philanthotoxin (the polyamine toxin, from the Egyptian digger wasp) was tested on responses of brainstem and spinal neurones in the pentobarbitone-anaesthetized rat to excitatory amino acids. 2. Philanthotoxin caused a dose-dependent reduction of responses to quisqualate, alpha-amino-3-hydroxy-5-phenyl-4-isoxazolepropionate (AMPA) and kainate with little effect on those to N-methyl-D-aspartate (NMDA). 3. The time-course of this antagonist action was slow. In particular the rate of recovery was dependent on frequency of ejection of the agonist. This agonist-dependent recovery suggests that philanthotoxin has a channel blocking mode of action on mammalian central neurones.

Species-specific sequences in the genus Solanum: identification, characterization, and application to study somatic hybrids of S. brevidens and S. tuberosum

To aid in the identification and analysis of somatic hybrids between potato (Solanum tuberosum, dihaploid line PDH 40) and the non tuber-bearing wild species S. brevidens, a series of species-specific repetitive DNA sequences have been isolated. This was accomplished by making libraries of HaeIII-digested total DNA of S. tuberosum and S. brevidens, by cloning fragments into the SmaI site of plasmid pUC18 and transforming them into E. coli (JM83). The S. brevidens library consisted of 1,000 recombinant clones, and that of S. tuberosum, 700. Nitrocellulose filters with recombinant clones were hybridised to nick-translated total DNA of S. brevidens and also S. tuberosum, and, following autoradiography, clones that hybridised strongly to the DNA of only one of the species were chosen. Two highly repeated S. brevidens clones (pSB1, 400 bp and pSB7,210 bp), one highcopy-number s. tuberosum clone (pST10, 200 bp) and one low-copy-number sequence of S. tuberosum (pST3, 1.5 kbp) were selected for further analysis by Southern hybridisation to digested total DNA. Clone pSB7 gave a ladder pattern on hybridisation to EcoR1-digested total DNA of S. brevidens, with signals at multiples of 200 bp DNA. Using these probes it was possible to verify the hybridity of putative hybrids of dihaploid S. tuberosum and S.brevidens, and to confirm by Southern analysis and by slot blots the parental genome dosage of hexaploid hybrids (two s. brevidens: one S. tuberosum, and vice-versa). The S. tuberosum-specific probe, pSTIO, hybridised with DNA of three other tuber-bearing wild species (S. hjertingii, S. capsicibaccatum and S. berthaultii). A squash-blot procedure was developed using the probes that would allow early identification of somatic hybrid callus. There are a number of useful applications of such species-specific probes in the identification and analysis of somatic hybrids.

Specificity of rheumatoid factors in relation to the disease state in rheumatoid arthritis

Rheumatoid factors found in patients with rheumatoid arthritis react with human IgG and with IgG from some other species. The levels of rheumatoid factor give some indication of prognosis, albeit a rather poor one in this highly variable disease. The high degree of variability may, in part, be due to differences in the fine specificity of the rheumatoid factor in each individual patient, leading to differences in the types of immune complex formed. To study this hypothesis the fine specificity of rheumatoid factors of the IgM, IgA, and IgG classes for IgG from human, baboon, orangutan, macaque, owl monkey, gorilla, marmoset, cow, pig, sheep, goat, horse, mouse, and chicken was examined. Differential reactivity for these species was found and associations between the presence of rheumatoid factor and the development of moderate or severe erosions.

Prognostic use of a QRS scoring system after hospital discharge for initial acute myocardial infarction in the Framingham cohort

Myocardial infarct size is an important risk factor for survival after acute myocardial infarction (AMI). The purpose of this study was to determine the prognostic value of myocardial infarct size, as estimated by the Selvester 54-criteria/32-point QRS scoring system, in the Framingham cohort. During the first 30 years of the Framingham Heart Study, a total of 384 participants developed an AMI requiring hospitalization; from this group, 243 patients met the following inclusion criteria: (1) no electrocardiographic changes due to a previous infarction, (2) survival greater than 3 days after discharge from the AMI hospitalization and (3) no electrocardiographic evidence of conduction disturbances or ventricular hypertrophy at the time of their final in-hospital electrocardiogram. Univariate and multivariate analyses were performed to test the association of the QRS score, and other associated risk factors, with time until coronary heart disease-related death. QRS score was found to be significantly associated with outcome (p = 0.03), as was the systolic blood pressure before infarction (p greater than 0.001). Both univariate and multivariate analysis showed that a history of systolic hypertension was the variable most strongly associated with coronary heart disease-related death. Thus, identification of AMI survivors at high risk for subsequent mortality can be improved by routine blood pressure measurement before AMI, and QRS scoring of the electrocardiogram taken at hospital discharge.

Sarcoidosis presenting as recurrent alcohol-induced pancreatitis

A previously well 27-year-old Caucasian woman presented with five episodes of alcohol-induced abdominal pain over two years culminating in severe acute pancreatitis. Chest x-ray showed bilateral hilar lymphadenopathy and nodular pulmonary infiltrates. In hospital she developed a unilateral facial nerve palsy and other features of sarcoidosis, which was confirmed by biopsy of a pretracheal lymph node. No previous case is reported of sarcoidosis presenting with recurrent pancreatitis apparently induced on each occasion by moderate alcohol consumption and in the absence of other risk factors. Pancreatic involvement as part of sarcoidosis is uncommon but is treatable if recognized and has a good prognosis.

Urinary levels of proteins and metabolites in workers exposed to toluene. A cross-sectional study

We measured urinary excretion of albumin and retinol-binding proteins to investigate the occurrence of early renal dysfunction in 45 paint workers exposed principally to toluene, and in the same number of unexposed control subjects matched individually for sex and age. Two biological indicators of personal toluene absorption, namely urine hippuric acid and o-cresol, were also measured in the exposed subjects. A significantly higher level and increased prevalence of elevated retinol-binding protein in the urine of exposed workers was found, whereas no significant difference in urinary albumin concentration was seen between the two groups. Urinary concentrations of retinol-binding protein was correlated (r = 0.399, P less than 0.006) with that of o-cresol, but not with hippuric acid or employment duration. The results suggest a dose-dependent early tubular effect due to toluene exposure that might be useful for monitoring individuals exposed to toluene at work.

Molecular, cytogenetic and morphological characterization of somatic hybrids of dihaploid Solanum tuberosum and diploid S. brevidens

Fifty-eight somatic hybrid plants, produced both by chemical (11) and electrical fusion (47) of protoplasts of dihaploid Solanum tuberosum and S. brevidens, have been analysed by molecular, cytological and morphological methods. The potentially useful euploid plants constituted 34% of the total, of which 20% were tetraploid and 14% hexaploid; the remainder were aneuploid at the tetraploid, hexaploid and octoploid levels. Analysis of chloroplast DNA showed that 55% of hybrids contained chloroplasts from S. brevidens and 45% from S. tuberosum. Hexaploids, the products of three protoplasts fusing together, were analyzed with specific DNA probes, and this revealed that nuclear genome dosages could be either 2∶1 S. tuberosum∶S. brevidens, or vice-versa. Chloroplast types of hexaploids were not influenced by nuclear genome dosage, and all six possible combinations of genome dosage and chloroplast types were found amongst tetraploids and hexaploids. To examine the morphology of the hybrid population and its possible relation to the chromosome number and chloroplast DNA type, 18 morphological characteristics were measured on greenhouse-grown plants and analyzed by principal component and canonical variate analyses. Both analyses showed that nuclear ploidy has the most prominent influence on the overall morphology of the hybrids. Differential parental genome expression in the morphology of the hybrids is discussed. These results provide useful data on the range of genetic combinations that can be expected to occur amongst somatic hybrid plants.

Fasting urinary hydroxyproline: creatinine ratios in silicosis

Fasting urinary hydroxyproline: creatinine (HOP:C) ratios were measured in 74 patients with suspected (borderline) silicosis (10), simple silicosis (46) and complicated silicosis (9 silicotuberculosis, 4 massive fibrosis, and 5 combined silicotuberculosis and massive fibrosis) and in 18 healthy subjects (controls). There was no statistically significant difference in urinary HOP:C ratios between control subjects (mean 13.8, SD 3.6) and suspected silicotics (mean 18.0, SD 7.6); however, urinary HOP:C ratios were significantly higher in both simple silicosis (mean 25.0, SD 9.9, p less than 0.001) and complicated silicosis (silicotuberculosis and progressive massive fibrosis) (mean 28.6, SD 11.3; p less than 0.001). Urinary HOP:C ratios appeared to show a graduated increase to their highest levels in category 2 silicosis and thereafter remained constant or declined slightly in category 3 silicosis and massive fibrosis. The results support the suggestion that urinary hydroxyproline might be useful as an indicator of disease progression in established silicosis. However, further longitudinal studies are needed to confirm its predictive value.

Antitussive agents as N-methylaspartate antagonists: further studies

The relative potencies of ketamine and the morphinan derivatives dextrorphan, dextromethorphan, and levorphanol as antagonists of the excitatory actions of N-methylaspartate on rat spinal neurones in vivo were examined, both following their microelectrophoretic administration and, with the exception of levorphanol, after intravenous injection. Applied microelectrophoretically, dextrorphan was a more potent N-methylaspartate antagonist than ketamine, levorphanol, or dextromethorphan. After systemic administration, however, dextrorphan was rather less potent than ketamine in this respect, whereas dextromethorphan remained less potent than either ketamine or dextrorphan. Noscapine, an antitussive that lacks anticonvulsant activity, failed to reduce selectively responses to N-methylaspartate as did papaverine, an isoquinoline structurally related to noscapine, and triprolidine, an antihistamine commonly found in proprietary cough medicines. The results are discussed with particular reference to the potential of the compounds tested as anticonvulsant and neuroprotective agents in vivo.

A system for accelerated provision of hearing aids to residents of homes for the elderly

A study was undertaken to detect undiagnosed deafness in elderly people, living in Part III Residential Homes in North Tees, South Tees and Hartlepool Health Districts, to provide hearing aids and to estimate the subsequent success in rehabilitation. The residents were referred by the senior staff in the homes and assessed by a doctor and audiology technician in a domiciliary setting. Those found to have a significant hearing impairment were prescribed hearing aids without formal pure tone audiometry. A pilot study compared the method of hearing evaluation employed with such conventional testing. Six months after fitting, the degree of compliance with aiding was assessed. The results show a significant level of undiagnosed deafness in the community and, with this method of provision, an acceptance rate of 41.2 per cent of those recommended for aiding at six months which is higher than suggested by previous similar studies of this population.

Isolation, culture, and regeneration of plants from potato protoplasts

A technique is described for the routine isolation of protoplasts from storage parenchyma cells of potato tubers grown in vitro. The protoplasts typically contained many starch grains. On culture, most of the starch grains were metabolised during the first 7 days, after which the cells began to divide. Following further culture, protoplast-derived colonies and calli were obtained, from which shoots and intact plants were regenerated. Cytological study of regenerated plants showed that the majority were octaploid or aneuploid at the octaploid level. This aspect is compared with plants regenerated from mesophyll protoplasts of potato. The use of tuber protoplasts for studies on tissue-specific transient gene expression of chimeric gene constructs, following their introduction into the protoplasts by electroporation, is discussed, together with the uses of tuber protoplasts in fundamental physiological and biochemical studies.

The evolution of a simplified method for interpretation of EEG in the preterm neonate

We describe the evolution of a simplified method for the interpretation of serial EEG in preterm neonates which was tested in a first sample and revised and improved in a second sample of preterm neonates. There were 185 EEGs in the first sample and 206 EEGs in the second sample. The interpretation of the EEGs was related to mental, motor and neurological outcome in late infancy. Serial EEG is an excellent indicator of brain function in the preterm neonate.

Chemical models for the lethality curves of toxic metal ions

Several equilibrium models are presented for the calculation of the lethality curves due to toxic metal ions. In the first, a generalized Langmuir model is used to examine the occupancy of linear arrays of 1, 2, ..., 6 interacting adsorption sites on a macromolecular species. This model permits one to take into account cooperative or anticooperative interaction of occupied adjacent sites. In the second model, a variety of nonlinear distributions of interacting sites (in triangular, square, tetrahedral, and octahedral array) are analyzed, and the corresponding adsorption isotherms are calculated. The third model treated, the Ising model, represents a linear infinite array of sites with nearest-neighbor interactions. The fourth and fifth models examined are the Bragg-Williams model and the quasi-chemical model, both of which permit approximate treatment of infinite arrays of adsorption sites having arbitrary numbers of interacting nearest neighbors. These models are then combined with the assumption that the differential distribution of mortality is a known function of the fraction of sites occupied by the toxic metal ion to generate lethality curves. Results are computed for the special case in which the differential mortality distribution is Gaussian, and it is shown that all of the models are capable of generating lethality curves of the sort found experimentally when plots are made of percentage lethality versus log dosage. The models can also be used for situations in which toxic effects other than lethality arise from the interaction of a toxic molecule or ion with more than one site on a linear macromolecule or for reactions involving certain other arrays of specified configuration.

Stable transformation of sugarbeet protoplasts by electroporation

Conditions were optimized for the culture, antibiotic selection and stable transformation by electroporation of suspension culture protoplasts of sugarbeet,Beta vulgaris L.. Highest plating efficiencies (up to 65% at day 21) were obtained if protoplasts were cultured in PGO salts (de Greef and Jacobs, 1979) supplemented with 0.1 mg/1 2,4-D, 0.01 mg/l BAP and 9% mannitol, and in 0.6% agarose rather than in liquid medium. Sensitivity to kanamycin also depended on whether protoplasts were cultured in liquid or agarose medium. Stable transformation of protoplast-derived colonies, as determined by resistance to kanamycin and Southern blot analysis, was achieved by electroporation using both rectangular and exponentially-decaying pulses.

Field assessment of dihaploid Solatium tuberosum and S. brevidens somatic hybrids

Following both chemical and electrical fusion of protoplasts of a dihaploid line of potato (Solanum tuberosum), (PDH40), with those of the wild species, Solanum brevidens, 11 and 40 somatic hybrid plants, respectively were obtained. Fifteen of these somatic hybrid genotypes and the two parents were studied further in a small field trial to assess field performance and phenotypic variability. In the UK, somatic hybrid plants are classified as genetically engineered organisms, and the UK Advisory Committee on Genetic Manipulation have imposed various restrictions on field experiments. Examination of the somatic hybrids in the field showed extensive phenotypic variability, and no two genotypes were identical. Some of the variation reflected changes in chromosome numbers, but other factors were also involved. Half the somatic hybrid genotypes produced tubers in the field, although the tubers were smaller and differed morphologically from those of PDH40. The results of the study suggest that the extent of somaclonal variation manifested in somatic hybrids is greater than that found in protoplast-derived plants of potato. The implications of this observation and the current regulations concerning field experiments of somatic hybrid plants in the UK are discussed.

A comparison between the in vivo and in vitro activity of five potent and competitive NMDA antagonists

1. Phosphonate analogues of glutamate have been tested and compared as N-methyl-D-aspartate (NMDA) antagonists in electrophysiological and binding experiments. The compounds tested were three established NMDA antagonists: D-2-amino-5-phosphonopentanoate (D-AP5), DL-2-amino-7-phosphonoheptanoate (DL-AP7), 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonate (CPP), and two novel putative NMDA antagonists: 3-(2-carboxypiperidin-4-yl)propyl-1-phosphonate (CPPP) and 3-(2-carboxy-piperidin-4-yl)methyl-1-phosphonate (CPMP). 2. When administered electrophoretically to rat spinal neurones in vivo, these compounds were found to be selective NMDA antagonists with little effect on excitations evoked by quisqualate and kainate. CPMP and CPPP were approximately equipotent with CPP and about 5 times more potent than D-AP5. 3. Following systemic administration, 2-5 mg kg-1 i.v. of CPP, CPMP and CPPP reduced NMDA-evoked excitations by 70-100% whereas 50-100 mg kg-1 of D-AP5 and DL-AP7 produced a similar effect. The onset of the effects required 20-30 min and lasted more than six hours. 4. On bath application to cortical wedges, the IC50 values (microM) for antagonism of 40 microM NMDA were: CPP, 0.64 +/- 0.06 (mean +/- s.e.mean; n greater than 4); CPMP, 1.65 +/- 0.13; CPPP 0.89 +/- 0.09; D-AP5, 3.7 +/- 0.32; DL-AP7, 11.1 +/- 2.1; and DL-AP4 and DL-AP6 were inactive at 100 microM. 5. In binding studies with [3H]-CPP, the Ki values (nM) were: CPP, 446 + 150 (mean + s.e.mean; n > 3); CPMP, 183 + 74 and CPPP, 179 +/- 13 whereas against NMDA (lO microM)-stimulated [3H]- TCP (thienylcyclohexylpiperidine) binding the ICjo values (microM) for CPMP and CPPP respectively were 5.6 + 2.7 and 4.5 + 2.2. 6. Systemic administration of CPPP and CPMP, at doses sufficient to antagonize NMDA, also reduced cardiovascular responses to 5-hydroxytryptamine (Bezold-Jarisch reflex). This illustrates a role for NMDA receptors in central cardiovascular control. 7. The results indicate the systemic doses of piperidine and piperazine analogues of D-AP5 which may be used for assessing the role ofNMDA receptors in central synaptic function.

Production of somatic hybrids by electrofusion in Solanum

Conditions are described for large scale electrofusion of mesophyll protoplasts of dihaploid S. tuberosum with those of diploid S. brevidens. Overall fusion frequencies of 20%-30% were achieved, and following fusion, large numbers of protoplast-derived calli were obtained. Putative somatic hybrid plants were selected from the regenerated shoots by examining their morphological characteristics. Twenty-one somatic hybrids were confirmed by isoenzyme analysis and six somatic hybrids were further confirmed by Southern hybridization. Tetraploid hybrids were obtained, but cytogenetic studies indicated that more of the regenerated hybrids were hexaploid than had previously been found following chemical fusion of the same partners. Some advantages of electrofusion over chemical fusion are discussed.

Resistance to potato leaf roll virus and potato virus Y in somatic hybrids between dihaploid Solanum tuberosum and S. brevidens

Many somatic fusion hybrids have been produced between a dihaploid potato Solanum tuberosum and the sexually-incompatible wild species S. brevidens using both chemical and electrical fusion techniques. S. brevidens was resistant to both potato leaf roll virus (PLRV) and potato virus Y (PVY), the viruses being either at low (PLRV) or undetectable (PVY) concentrations as determined by enzyme-linked immunosorbent assay (ELISA). The S. tuberosum parent was susceptible to both viruses. A wide range of resistance, expressed as a decrease in virus concentration to both viruses was found amongst fusion hybrids, four of which were especially resistant. The practicality of introducing virus resistance from S. brevidens into cultivated potatoes by somatic hybridisation is discussed.

Use of initial ST-segment deviation for prediction of final electrocardiographic size of acute myocardial infarcts

The decision to administer thrombolytic therapy for limitation of acute myocardial infarction (AMI) size must occur when only the history, physical examination and 12-lead electrocardiogram of a patient are available. A method that could quickly assess the amount of jeopardized myocardium would greatly aid the physician. This study developed formulas from 68 anterior and 80 inferior AMI patients using the extent of initial ST-segment deviation (ST delta) to predict the final AMI size estimated by the Selvester QRS score in a population not receiving reperfusion therapy. Inclusion required: initial anterior or inferior AMI; admission electrocardiogram less than or equal to 8 hours after the onset of symptoms with evidence of epicardial injury; elevated creatine kinase-MB; a predischarge electrocardiogram taken greater than or equal to 72 hours after admission; and no AMI extension before the predischarge electrocardiogram. The extent of epicardial injury was quantified by counting the number of leads with greater than or equal to 0.1 mm ST delta, by the sum (sigma) of ST delta in all leads and by the sigma ST delta in the lead groups associated with each AMI location. These results were compared to the AMI size estimated from the predischarge electrocardiogram. Univariable and multivariable analyses generated these formulas for AMI size: anterior = 3[1.5 (number leads ST increases) - 0.4]; inferior = 3[0.6 (sigma ST increases II, III, aVF) + 2.0]. Thus, formulas based on quantitative measurements of ST delta on the admission electrocardiogram are predictive of final QRS-estimated AMI size, and may be useful in determining the efficacy of acute reperfusion therapy.

Plant tissue culture

Plant tissues normally grow in an organized fashion in which specific cell types differentiate from nonspecialised meristematic cells. Plant developmental processes can be modified by culture in vitro in a suitable nutrient medium and with the application of plant growth regulators. The interactions of the main growth regulators can be complex, but at the simplest level auxins can cause cell enlargement and division, cytokinins cause cell division, gibberellins cause elongation, and abscisic acid inhibits growth (1). When meristems are cultured, it is possible to maintain organization and multiply such meristems, and this is the basis of micropropagation. If a suitable combination of growth regulators is chosen, however, cultured tissues can be grown in a disorganized and undifferentiated way to form callus. Single isolated wall-less cells, protoplasts, can also be released from tissues following enzymatic degradation of cell walls, and these can be cultured to form callus. In both cases the aim is to regenerate intact plants from disorganized callus, usually by manipulating growth regulator concentrations so that the cytokinin/auxin ratio is increased (2).

Determination of endogenous abscisic acid levels in immature cereal embryos during in vitro culture

Levels of endogenous abscisic acid (ABA) in immature wheat (Triticum aestivum cv. Timmo) and barley (Hordeum vulgare cv. Golden Promise) embryos have been determined by enzyme-linked immunosorbent assay. Embryos of both cereal species showed an increase in ABA content during development on the parent plant. Immature embryos were excised and cultured in vitro on nutrient media that led to precocious germination or on media containing 9% (w/v) mannitol that maintained their developmental arrest. Barley and wheat embryos responded to these culture conditions in an identical manner with respect to changes in morphology, fresh weight, protein and lectin content. However, in complete contrast, the ABA content of barley embryos increased by an order of magnitude during culture on mannitol, whereas that of wheat embryos showed no significant change. The results are discussed within the context of the role of ABA in the regulation of embryo development.

The permeability of electroporated cells and protoplasts of sugar beet

A simple method has been developed to determine the changes in permeability of protoplasts and intact cells when electroporated. Cells and protoplasts of sugar beet, Beta vulgaris L., were subjected to electric pulse treatments of different field strengths, pulse number and pulse duration, and the ability to accumulate and retain the hydrophilic dye phenosafranine was determined spectrophotometrically. Results of timecourse studies of phenosafranine accumulation and retention indicated that pores are formed or enlarged rapidly in the plasmamembrane and remain permeable to phenosafranine for relatively long periods; the half-life of the 'pores" was temperaturedependent. Both cells and protoplasts retained the highest levels of phenosafranine when supplied with a series of five rectangular pulses of 50 μs duration and of field strength 2500 V·cm(-1). If these parameters were exceeded, The phenosafranine content was reduced, concomitant with a decline in viability as indicated by fluorescein-diacetate staining, indicating the loss of the integrity of the plasmamembrane. The pattern of accumulation and retention by protoplasts of radioactivity from [(3)H]pABD1, a modified bacterial plasmid, was similar to that of phenosafranine, but uptake of the plasmid by cells was not demonstrated. The mothod can be used to determine conditions for the optimum permeabilization of protoplasts for direct gene transfer.

Chromosome variation in dividing protoplasts and cell suspensions of wheat

The cytology of bread wheat (Triticum aestivum) suspension lines, recycled lines (selected for high division frequency) and their dividing protoplasts, have been examined. Extensive numerical and structural chromosome variation was present in all the lines. The most frequently observed chromosome numbers were around 2n=32, indicating that considerable chromosome loss from the normal wheat complement (2n=6x=42) had occurred during selection of the lines. Chromosome aberrations also indicated loss of chromosome arms and chromosome segments. The implications of this variation for studies on transformation and for the potential regeneration of whole plants from protoplasts of bread wheat are discussed.

The effect of dietary protein on glomerular filtration rate in normal subjects

The acute effect of the ingestion of 90 g of protein as meat and as milk protein (Casilan) on glomerular filtration rate (assessed by creatinine clearance) was examined in healthy subjects. The creatinine clearance increased 1.5 hours after the ingestion of meat and remained elevated for a further 2.5 hours. The mean maximal increase in creatinine clearance was 18 ml/min. Casilan on the other hand did not produce a significant increase in the creatinine clearance. When 6 subjects ingested 90 g of protein as Casilan daily for 5 days, the creatinine clearance increased after a delay of 3 to 4 days. When the same subjects increased their meat protein intake by 90 g as meat daily for 5 days, the creatinine clearance increased from the first day (by 23 ml/min) and remained elevated throughout the 5 days of study. We conclude that the effect of protein on glomerular filtration rate depends on the type of protein.

Transient gene expression in electroporated protoplasts and intact cells of sugar beet

Factors influencing the transient expression of introduced foreign DNA in electroporated protoplasts and intact cells of sugar beet were determined by assaying for the activity of chloramphenicol acetyltransferase (CAT), using a rectangular pulse generating system. Extractable CAT activity depended upon 1) applied plasmid DNA concentration, 2) protoplast density, 3) the interaction between pulse field strength, duration, number, time interval between pulses and the resultant effect on culture viability, and 4) the physiological state of the protoplasts. Mesophyll protoplasts were more susceptible to damage by electroporation, and were more specific in their requirement for electroporations which allowed CAT expression, than were protoplasts derived from suspension culture cells. CAT activity was also demonstrated, at low levels, after electroporation of intact suspension culture cells, and could be increased by pectinase treatment of the cells before electroporation.

Identification of the optimal electrocardiographic leads for detecting acute epicardial injury in acute myocardial infarction

Current coronary care electrocardiographic (ECG) monitoring techniques are aimed at detection of cardiac arrhythmias rather than myocardial ischemia. However, in patients with acute myocardial infarction (AMI) who undergo reperfusion therapy, monitoring ST-segment deviation could provide an early noninvasive indicator of coronary artery reocclusion. In this study, the admission 12-lead ECGs of patients with initial AMI were used to propose optimal lead locations for ST-segment monitoring. The study population was selected from consecutive Duke University Medical Center admissions during 1965 to 1981 who met the following inclusion criteria: chest pain for no more than 8 hours, initial AMI documented by ECG and 3 of 4 enzyme criteria, greater than or equal to 0.1 mV (1 mV = 10 mm) of ST elevation in at least 1 of the standard 12 leads (not aVR) on admission ECG, and no ECG evidence of conduction disturbances, ventricular hypertrophy or tachycardia. ST-segment deviation was quantified; AMI location was assigned based on the lead with maximal deviation. Of the 80 patients who had an inferior AMI, lead III was both the most frequent location for ST elevation (94%) and the most common site with maximal ST deviation. Lead V2 had the highest incidence of ST-segment depression (60%). In the 68 patients who had an anterior AMI, lead V2 had the highest frequency of ST elevation (99%). Leads V2 and V3 were the most common sites of maximal elevation. Thus, for monitoring ST deviation, leads III and V2 may be superior to leads II and V1, which are commonly used in arrhythmia monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatic hybridization of amino acid analogue-resistant cell lines of potato (Solanum tuberosum L.) by electrofusion

Intraspecific somatic hybridization between amino acid analogue-resistant cell lines of potato (Solanum tuberosum L.) has been carried out following electrofusion of protoplasts. In initial analytical electrofusion experiments (1 mm electrode separation) optimal fusion conditions were determined by changing the fusion medium (addition of Ca and/or spermine) and the electrical parameters. Subsequently, in large scale experiments, cell suspension protoplasts of aec-1, a variant resistant to AEC, were fused with the same type of protoplasts of 5mt-26 or 5mt-27, both variants resistant to 5MT and cross-resistant to 3 FT. After an extensive selection procedure only somatic hybrid lines of aec-1 + 5mt-26 were obtained. The resistance traits of aec-1 and 5mt-26 were expressed fully, indicating that the variant characters involved are transmitted dominantly. Quantitative examination of the free amino acid content revealed characteristics of both the parental cell lines in most of the somatic hybrids. However, initially selected double resistant colonies from fusions of aec-1 + 5mt-27 lines appeared not to be somatic hybrids.

Lectin levels in tissues of cultured immature wheat embryos

Levels of wheat germ agglutinin have been determined by radioimmunoassay in tissues of immature wheat embryos cultured under different conditions in order to determine the suitability of the lectin as a marker for somatic embryogenesis. Embryos cultured on media favouring continued embryo development accumulated lectin in a similar manner to zygotic embryos in planta unless precocious germination occurred. Embryos cultured on media containing 2,4-D produced callus, and some of this developed somatic embryos. Both embryogenic and non-embryogenic callus contained WGA, that in non-embryogenic callus possibly arising from developmentally arrested root primordia.

The results of checking a scoring system for neonatal seizures

We report the result of checking a scoring system for neonatal seizures in which information from the EEG, etiology, neurological examination, seizure type and birth weight are combined to predict neurological sequelae and to make decisions about treatment. The results for two samples are presented and compared. The first sample included 96 neonates; 103 neonates were evaluated in the second sample, yielding data from 199 neonates in the combined samples. The scoring system served to separate neonates who had neurological sequelae at age 10 months or more from those who did not. In addition, the scoring system provided an excellent guide for treatment of neonatal seizures. Neonates with scores less than or equal to 4 can be safely discharged from the hospital without anticonvulsant therapy. At age three months a score of less than or equal to 5 can be used as a guideline for discontinuing anticonvulsant therapy.

Improved efficiency of genotype-dependent regeneration from protoplasts of important potato cultivars

The regeneration of protoplasts from potato (Solanum tuberosum L.) cvs. Desiree and King Edward has been significantly improved. Different shoot culture media were required for the release of viable protoplasts from cvs. Maris Piper and Desiree, and the response of protoplasts to different culture conditions depended upon the cultivar genotype of the protoplast source. Using protoplast isolation media containing 6mM CaCl2 improved protoplast viability and culture in enriched media lead to the reproducible and relatively efficient recovery of colonies from protoplasts of these cultivars. Over 70% of protoplast-derived calli from King Edward and Desiree regenerated shoots. Many shoots were grown to mature plants in soil. This is the first report of the regeneration of mature Desiree plants from protoplasts.