International publication trends of JABA authorship

The present study addressed international publication trends in JABA authorship between 1970 and 1999. First, we analyzed authorship patterns to identify trends in the appearance of new first authors, unfamiliar authors, and frequent contributors. Second, articles were assigned to either a North American or an international category. The data show a decline in the number of articles by new authors and an increase in the publications of frequent contributors from North America. Trends are shown in comparison to those from the American Journal on Mental Retardation.

Novel assays for the detection of botulinum toxins in foods

Currently the only accepted method for the detection of botulinum neurotoxin in contaminated samples is the mouse bio-assay. Although highly sensitive this test has a number of drawbacks: it is expensive to perform, lacks specificity and involves the use of animals. With increasing resistance to such animal tests there is a need to replace the bio-assay with a reliable in vitro test. Over the past six years it has been demonstrated that all the botulinum neurotoxins act intracellularly as highly specific zinc endoproteases, cleaving proteins involved in the control of secretion of neurotransmitters. In the work described, this enzymatic activity has been utilised in assay formats for the detection in foods of neurotoxin from the serotypes involved in food-borne outbreaks in man. These assays have been shown to have a greater sensitivity, speed and specificity than the mouse bio-assay. It is envisaged that such assays will prove realistic alternatives to animal based tests.

Simultaneous EEG and EDA measures in adolescent attention deficit hyperactivity disorder

Adolescent unmedicated ADHD males and age- and sex-matched normal control subjects were examined simultaneously using EEG and EDA measures in a resting eyes-open condition. ADHD adolescents showed increased absolute and relative Theta and Alpha1 activity, reduced relative Beta activity, reduced skin conductance level (SCL) and a reduced number of non-specific skin conductance responses (NS.SCRs) compared with the control subjects. Our findings indicate the continuation of increased slow wave activity in ADHD adolescents and the presence of a state of autonomic hypoarousal in this clinical group.

Vinblastine pharmacokinetics in patients with non-small cell lung cancer given cisplatin

The pharmacokinetics of vinblastine were studied in 16 patients with non-small cell lung cancer after a bolus intravenous dose of 3 mg/m2 given before or after cisplatin (100 mg/m2). Venous blood was collected at 0, 10, and 36 hr for analysis by radioimmunoassay. The mean plasma vinblastine concentration at 10 hr was similar when vinblastine was given before (4.8 ng/ml; 95% CI, 3.2-6.3) or after cisplatin (4.9 ng/ml; 95% CI, 2.7-7.1). Plasma vinblastine concentrations in patients given cisplatin were higher than previously reported in patients given vinblastine alone. Patients with plasma vinblastine concentrations less than 2.75 ng/ml at 10 hr experienced less severe neutropenia (37% fall in neutrophil count; 95% CI, 18-55) than those with levels greater than 2.75 ng/ml (69% fall in neutrophil count; 95% CI, 62-77). In conclusion, the pharmacokinetics of vinblastine predict the severity of neutropenia and may be altered when given in conjunction with cisplatin.

Opioid analgesia: new information from gene knockout studies

The cloning of opioid peptides and receptors has led to the development of knockout mice deficient in a gene encoding for each peptide and each receptor. The major advantage of the knockout approach is the complete selectivity that the removal of a protein encoded for by a gene provides. These knockout animals are adding to our knowledge of the physiology, pathophysiology and pharmacology of opioid systems. In addition, they are providing real impact in addressing the long-standing debates over receptor subtype heterogeneity and functional cooperativity between receptor subtypes.

A highly conserved 3-methylhistidine modification is absent in yeast actin

To identify a protein histidine methyltransferase from Saccharomyces cerevisiae, we examined purified actin for the presence of the highly conserved 3-methylhistidine residue at position 73 by amino acid analysis of the whole protein and by amino acid analysis and mass spectrometry of the corresponding tryptic fragment. Surprisingly, we found that His-73 is not modified. A similar lack of modification was also found in actin from the yeast Candida albicans, while rabbit muscle actin revealed the expected 3-methylhistidine residue. Phylogenetic analysis of actin sequences suggests that this modification was introduced in evolution after the divergence of yeast from higher eukaryotic organisms, including unicellular eukaryotes such as Acanthamoeba, Dictyostelium, and Physarum, whose actins contain 3-methylhistidine. Our methodology for the analytical determination of 3-methylhistidine in actin offers an improved approach for investigating histidine methylation in proteins.

Polymorphic forms of the protein L-isoaspartate (D-aspartate) O-methyltransferase involved in the repair of age-damaged proteins

The protein L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1) can initiate the repair of age-damaged aspartyl and asparaginyl residues of intracellular proteins. The human gene PCMT1 encoding this enzyme has at least four polymorphic sites, one of which results in two major isoforms with either an Ile residue or a Val residue at amino acid position 119. The frequencies of the alleles encoding the Ile119 and Val119 variants are similar in Caucasian populations, but a predominance of the Ile119 allele exists in Asian and African populations. Analyses of the enzymatic activities of the Ile119 and Val119 variants in red blood cell lysates show that the higher specific activity and thermostability of the Ile119 isoform is balanced by the potentially compensating higher substrate affinity of the Val119 isoform. In a preliminary attempt to find an association between genotype frequency at the PCMT1 locus and healthy aging, we compared the distribution of genotypes in a healthy older population of Ashkenazi Jewish individuals with that in a younger ethnically matched control group. We found that 65% of the healthy older population had the heterozygous genotype, greater than the 50% expected by Hardy-Weinberg equilibrium, suggesting a possible selection for having both alleles of the repair methyltransferase in successful aging. Three additional polymorphisms in noncoding regions of the methyltransferase gene were found to be biallelic and demonstrated nonrandom association in a specific haplotype with the codon 119 polymorphism. Finally, we also detected a heterozygous mutation in the splicing branch site of intron 2 that did not appear to affect activity. This study will help define the normal physiological range of activity for this repair methyltransferase and give us a better understanding of its role in the processes of aging and disease.

Development of an in vitro bioassay for Clostridium botulinum type B neurotoxin in foods that is more sensitive than the mouse bioassay

A novel, in vitro bioassay for detection of the botulinum type B neurotoxin in a range of media was developed. The assay is amplified by the enzymic activity of the neurotoxin's light chain and includes the following three stages: first, a small, monoclonal antibody-based immunoaffinity column captures the toxin; second, a peptide substrate is cleaved by using the endopeptidase activity of the type B neurotoxin; and finally, a modified enzyme-linked immunoassay system detects the peptide cleavage products. The assay is highly specific for type B neurotoxin and is capable of detecting type B toxin at a concentration of 5 pg ml(-1) (0.5 mouse 50% lethal dose ml(-1)) in approximately 5 h. The format of the test was found to be suitable for detecting botulinum type B toxin in a range of foodstuffs with a sensitivity that exceeds the sensitivity of the mouse assay. Using highly specific monoclonal antibodies as the capture phase, we found that the endopeptidase assay was capable of differentiating between the type B neurotoxins produced by proteolytic and nonproteolytic strains of Clostridium botulinum type B.

Life threatening laryngeal toxicity following treatment with combined chemoradiotherapy for nasopharyngeal cancer: a case report with review of the literature

Nasopharyngeal carcinoma is a rare cancer in Western society, however there is a higher incidence in Asian. Chinese and African populations. A significant number of Asians reside in Australia, and consequently patients with nasopharyngeal carcinoma are an increasing clinical problem. Radiotherapy has been the predominant treatment in the past, but more recently multi-modality treatments have been utilised. The results of an Intergroup trial, coordinated by the Southwest Oncology Group (SWOG) demonstrated markedly superior progression free and overall survival for combined chemoradiotherapy compared to radiotherapy alone. At three years progression free survival was 24% for the radiotherapy arm and 69% for the chemoradiotherapy group (P < 0.001), and three-year survival was 47% for the radiotherapy arm compared with 78% for the combined arm (P = 0.005). There was minimum toxicity reported for either of the arms and no treatment related deaths. Based on these survival data the administration of concomitant cisplatin and radiotherapy has become standard of care for nasopharyngeal carcinoma in the USA. Our institution has also adopted a similar combined therapy protocol for patients with stage III and IV nasopharyngeal cancer and good performance status. The patients treated at our institution have experienced significant side effects. We describe the case of a woman so treated with this protocol who subsequently developed severe life threatening laryngeal necrosis.

Phenotypic analysis of seizure-prone mice lacking L-isoaspartate (D-aspartate) O-methyltransferase

Within proteins and peptides, both L-asparaginyl and L-aspartyl residues spontaneously degrade, generating isomerized and racemized aspartyl residues. The enzyme protein L-isoaspartate (D-aspartate) O-methyltransferase (E.C. 2.1.1.77) initiates the conversion of L-isoaspartyl and D-aspartyl residues to normal L-aspartyl residues. This "repair" reaction helps to maintain proper protein conformation by preventing the accumulation of damaged proteins containing abnormal amino acid residues. Pcmt1-/- mice manifest two key phenotypes: a fatal seizure disorder and retarded growth. In this study, we characterized both phenotypes and demonstrated that they are linked. Continuous electroencephalogram monitoring of Pcmt1-/- mice revealed that abnormal cortical activity for approximately 50% of each 24-h period, even in mice that had no visible evidence of convulsions. The fatal seizure disorder in Pcmt1-/- mice can be mitigated but not eliminated by antiepileptic drugs. Interestingly, antiepileptic therapy normalized the growth of Pcmt1-/- mice, suggesting that the growth retardation is due to seizures rather than a global disturbance in growth at the cellular level. Consistent with this concept, the growth rate of Pcmt1-/- fibroblasts was indistinguishable from that of wild-type fibroblasts.

Effect of peroxisome proliferator-activated receptor alpha activators on tumor necrosis factor expression in mice during endotoxemia

Inflammatory mediators orchestrate the host immune and metabolic response to acute bacterial infections and mediate the events leading to septic shock. Tumor necrosis factor (TNF) has long been identified as one of the proximal mediators of endotoxin action. Recent studies have implicated peroxisome proliferator-activated receptor alpha (PPARalpha) as a potential target to modulate regulation of the immune response. Since PPARalpha activators, which are hypolipidemic drugs, are being prescribed for a significant population of older patients, it is important to determine the impact of these drugs on the host response to acute inflammation. Therefore, we examined the role of PPARalpha activators on the regulation of TNF expression in a mouse model of endotoxemia. CD-1 mice treated with dietary fenofibrate or Wy-14,643 had fivefold-higher lipopolysaccharide (LPS)-induced TNF plasma levels than LPS-treated control-fed animals. Higher LPS-induced TNF levels in drug-fed animals were reflected physiologically in significantly lower glucose levels in plasma and a significantly lower 50% lethal dose than those in LPS-treated control-fed animals. Utilizing PPARalpha wild-type (WT) and knockout (KO) mice, we showed that the effect of fenofibrate on LPS-induced TNF expression was indeed mediated by PPARalpha. PPARalpha WT mice fed fenofibrate also had a fivefold increase in LPS-induced TNF levels in plasma compared to control-fed animals. However, LPS-induced TNF levels were significantly decreased and glucose levels in plasma were significantly increased in PPARalpha KO mice fed fenofibrate compared to those in control-fed animals. Data from peritoneal macrophage studies indicate that Wy-14,643 modestly decreased TNF expression in vitro. Similarly, overexpression of PPARalpha in 293T cells decreased activity of a human TNF promoter-luciferase construct. The results from these studies suggest that any anti-inflammatory activity of PPARalpha in vivo can be masked by other systemic effects of PPARalpha activators.

Development of in vitro assays for the detection of botulinum toxins in foods

Currently the only accepted method for the detection of botulinum neurotoxin in contaminated samples is the mouse bioassay. Although highly sensitive this test has a number of drawbacks: it is expensive to perform, lacks specificity and involves the use of animals. With increasing resistance to such animal tests there is a need to replace the bioassay with a reliable in vitro test. Over the past six years it has been demonstrated that all the botulinum neurotoxins act intracellularly as highly specific zinc endoproteases, cleaving proteins involved in the control of secretion of neurotransmitters. In the work described, this enzymatic activity has been utilised in assay formats for the detection in foods of neurotoxin of the serotypes involved in food-borne outbreaks in man. These assays have been shown to have a greater sensitivity, speed and specificity than the mouse bioassay. It is envisaged that such assays will prove realistic alternatives to animal-based tests.

Validity of the heart rate deflection point as a predictor of lactate threshold during running

During an incremental run test, some researchers consistently observe a heart rate (HR) deflection at higher speeds, but others do not. The present study was designed to investigate whether differences in test protocols could explain the discrepancy. Additionally, we sought to determine whether the HR deflection point accurately predicts lactate threshold (LT). Eight trained runners performed four tests each: 1) a treadmill test for maximal O(2) uptake, 2) a Conconi test on a 400-m track with speeds increasing approximately 0.5 km/h every 200 m, 3) a continuous treadmill run with speeds increasing 0.5 km/h every minute, and 4) a continuous LT treadmill test in which 3-min stages were used. All subjects demonstrated an HR deflection on the track, but only one-half of the subjects showed an HR deflection on the treadmill. On the track the shortening of stages with increasing speeds contributed to a loss of linearity in the speed-HR relationship. Additionally, the HR deflection point overestimated the LT when a continuous treadmill LT protocol was used. In conclusion, the HR deflection point was not an accurate predictor of LT in the present study.

RNase treatment of yeast and mammalian cell extracts affects in vitro substrate methylation by type I protein arginine N-methyltransferases

Type I protein arginine N-methyltransferases catalyze the formation of omega-NG-monomethylarginine and asymmetric omega-NG, NG-dimethylarginine residues using S-adenosyl-l-methionine as the methyl donor. In vitro these enzymes can modify a number of soluble methyl-accepting substrates in yeast and mammalian cell extracts including several species that interact with RNA. We treated normal and hypomethylated Saccharomyces cerevisiae and RAT1 cell extracts with RNase prior to in vitro methylation by recombinant protein N-arginine methyltransferases and found that the methylation of certain polypeptides is enhanced up to 12-fold whereas that of others is diminished. 2-D gel electrophoresis of RNase-treated yeast extracts allowed us to tentatively identify the glycine- and arginine-rich (GAR) domain-containing proteins Gar1, Nop1, Sbp1, and Npl3 as major methyl-acceptors based on their known isoelectric points and apparent molecular weights. These results suggest that the methylation and RNA-binding of GAR domain-containing proteins in vivo may regulate protein-nucleic acid or protein-protein interactions.

A novel methyltransferase catalyzes the methyl esterification of trans-aconitate in Escherichia coli

We have identified a new type of S-adenosyl-L-methionine-dependent methyltransferase in the cytosol of Escherichia coli that is expressed in early stationary phase under the control of the RpoS sigma factor. This enzyme catalyzes the monomethyl esterification of trans-aconitate at high affinity (Km = 0.32 mM) and cis-aconitate, isocitrate, and citrate at lower velocities and affinities. We have purified the enzyme to homogeneity by gel-filtration, anion-exchange, and hydrophobic chromatography. The N-terminal amino acid sequence was found to match that expected for the o252 open reading frame at 34.57 min on the E. coli genomic sequence whose deduced amino acid sequence contains the signature sequence motifs of the major class of S-adenosyl-L-methionine-dependent methyltransferases. Overexpression of the o252 gene resulted in an overexpression of the methyltransferase activity, and we have now designated it tam for trans-aconitate methyltransferase. We have generated a knock-out strain of E. coli lacking this activity, and we find that its growth and stationary phase survival are similar to that of the parent strain. We demonstrate the endogenous formation of trans-aconitate methyl ester in extracts of wild type but not tam- mutant cells indicating that trans-aconitate is present in E. coli. Since trans-aconitate does not appear to be a metabolic intermediate in these cells but forms spontaneously from the key citric acid cycle intermediate cis-aconitate, we suggest that its methylation may limit its potential interference in normal metabolic pathways. We have detected trans-aconitate methyltransferase activity in extracts of the yeast Saccharomyces cerevisiae, whereas no activity has been found in extracts of Caenorhabditis elegans or mouse brain.

Thalamic projections of the fusiform gyrus in man

Previous retrograde degeneration studies have shown that human extrastriate visual cortex receives projections from the pulvinar, but their precise topographical organization remained unknown. We report on the distribution of thalamic projections originating in the fusiform gyrus, as studied with the Nauta method for anterogradely degenerating axons, in a case of right fusiform gyrus infarction. Ipsilaterally to the lesion, high density of afferents was found in the inferior pulvinar nucleus and a low density in the medial pulvinar nucleus as well as in the postero-inferior part of the reticular nucleus; no degenerating fibres were found in the lateral geniculate body. Degenerating axons were completely absent in the contralateral thalamus. Thus, there is a precise topographic relationship between parts of the extrastriate cortex and the pulvinar, suggesting segregated thalamocortical pathways for different parts of the extrastriate cortex. As in nonhuman primates, the human inferior temporal cortex has no direct output to the lateral geniculate body.

Short-term memory for colour following posterior hemispheric lesions in man

Short-term memory for colour was studied in five patients with circumscribed posterior hemispheric lesions. It was impaired independently of colour discrimination in one and more than colour discrimination in two patients. Two patients were normal in colour short-term memory, one with normal and one with deficient colour discrimination performance. Deficient performance in colour short-term memory was associated with bilateral lesions of the inferior occipitotemporal junction including the lateral part of the fusiform gyrus or with a unilateral lesion of the left parieto-occipital convexity. An additional colour constancy deficit was found in the former but not the latter condition. Thus, colour short-term memory can be affected independently of colour discrimination or colour constancy, and may depend on at least two distinct neural circuits.

Do damaged proteins accumulate in Caenorhabditis elegans L-isoaspartate methyltransferase (pcm-1) deletion mutants?

The protein l-isoaspartate (d-aspartate) O-methyltransferase (E.C. 2. 1.1.77) can initiate the conversion of isomerized and racemized aspartyl residues to their normal l-aspartyl forms and has therefore been hypothesized to function as a repair enzyme, responsible for helping to limit the accumulation of damaged proteins in aging organisms. In this study, the effect of a disruption in the pcm-1 gene encoding the l-isoaspartyl methyltransferase was investigated in the nematode Caenorhabditis elegans. It was found that damaged proteins recognized by this enzyme accumulated to significant levels during long-term incubation of both pcm-1+ and pcm-1- nematodes in a specialized larval stage called the dauer. The l-isoaspartyl methyltransferase-deficient mutants accumulated about twice the level of damaged proteins as the control nematodes during dauer aging. The mutants also accumulated higher levels of damage when both strains were incubated at 30 degrees C for up to 3 days. However, when nonviable nematodes were removed in a Percoll separation, similar levels of damage were measured between the two strains following both dauer aging and 30 degrees C incubation. Both strains were able to effectively eliminate damaged proteins recognized by the methyltransferase after recovery from dauer. Characterization of the methyl-accepting polypeptide substrates which accumulate in aged dauers revealed that although substrates of all molecular weights are present, the majority of substrates are peptides not precipitated by acetone. These results suggest that protein degradation, rather than repair, may be the major mechanism by which C. elegans eliminates damaged proteins containing l-isoaspartyl residues.

Informed consent and general surgeons' attitudes toward the use of pain medication in the acute abdomen

To determine general surgeons' attitudes about the use of pain medications in the acute abdomen, a questionnaire was mailed to all practicing general surgeons in Iowa. The questionnaire sought to determine the frequency with which pain medications were administered either before informed consent was obtained or before the patient with an acute abdomen was examined, and, in cases when pain medications were withheld, the reasons for withholding. The response rate was 72% (131 of 182). Seven percent of patients with an acute abdomen received pain medications by a general surgeon before being seen and 22% received pain medication by another physician in the emergency department (ED). Fifty-three percent of general surgeons responded that they believe pain medications preclude a patient from signing a valid informed consent; 78% reported that concerns about informed consent enter into their decision to withhold pain medications. Sixty-seven percent agreed that pain medications interfere with diagnostic accuracy, and 82% consider diagnostic accuracy when deciding to withhold pain medication.

The effect of mannitol versus dimethyl thiourea at attenuating ischemia/reperfusion-induced injury to skeletal muscle

OBJECTIVE

Mannitol is used as a treatment for skeletal muscle ischemia/reperfusion (I/R) injury in humans, despite the fact that its effectiveness in vivo is still disputed. The purpose of this study was to determine the efficacy of mannitol in attenuating I/R injury at the microcirculatory level.

METHODS

The study was designed as an experimental study with male Wistar rats. The main outcome measures were intravital microscopy, which was used to measure capillary perfusion, capillary and venular red blood cell velocity (VRBC), and leukocyte-endothelial interactions in the extensor digitorum longus muscle of the rat hind limb before and after ischemia. In addition, tissue injury was assessed during reperfusion with the fluorescent vital dyes bisbenzimide and ethidium bromide. Dimethyl thiourea (DMTU), a highly effective therapeutic agent of experimental I/R injury, was used as a positive control.

RESULTS

No-flow ischemia (2 hour) resulted in a 40% drop in capillary perfusion, a decline in capillary and venular VRBC, and increased leukocyte venular adherence and tissue infiltration. Tissue injury increased to a constant level during reperfusion. Mannitol attenuated capillary malperfusion during the first 60 minutes of reperfusion and prevented a decline in capillary VRBC. However, mannitol did not reduce tissue injury or leukocyte adherence and infiltration during reperfusion. By comparison, DMTU not only prevented the perfusion deficits and the increases in leukocyte venular adherence and tissue infiltration but significantly reduced the magnitude of tissue injury.

CONCLUSION

Our findings suggest that mannitol may be of limited value for the prevention of early reperfusion-induced injury after no-flow ischemia in skeletal muscle. By comparison, DMTU was highly efficacious by not only reducing microvascular perfusion deficits but by also reducing leukocyte-endothelial cell interactions and the incidence of cellular injury.