Effects of salinity on physicochemical properties of Alaska pollock surimi after repeated freeze-thaw cycles.

The effects of residual salt in surimi on physicochemical properties as affected by various freeze and thaw (FT) cycles were examined. Fresh Alaska pollock surimi was mixed with 4.0% sugar and 5.0% sorbitol, along with 8 combinations of salt (0.4%, 0.6%, 0.8%, and 1.0% NaCl) and sodium polyphosphate (0.25% and 0.5%), vacuum-packed, and stored at -18 degrees C until used. FT cycles (0, 6, and 9) were used to mimic long-term frozen storage. At the time of gel preparation, each treatment was appropriately adjusted to maintain 2% salt and 78% moisture. The pH decreased as residual salt increased during frozen storage. Salt extractable protein (SEP) decreased (P < 0.05) as FT cycles extended from 0 to 9. Regardless of residual salt and phosphate concentration during frozen storage, whiteness value (L*- 3b*) decreased (P < 0.05) as FT cycles extended, except for samples with 0.4% salt/0.5% phosphate and 0.6% salt/0.25% phosphate. Water retention ability (WRA) and texture significantly (P < 0.05) decreased at higher salt content (0.8% and 1.0%) after 9 FT cycles, indicating higher residual salt concentration can shorten the shelf life of frozen surimi. Our study revealed lower residual salt concentration and higher phosphate concentration are likely to extend the shelf life of frozen surimi.

Investigation of factors that affect the sensitivity of accelerator mass spectrometry for cosmogenic 10Be and 26Al isotope analysis.

We report experiments designed to improve accelerator mass spectrometry (AMS) of (10)Be and (26)Al for a wide range of geological applications. In many cases, the precision of the AMS isotope ratio measurement is restricted by counting statistics for the cosmogenic isotope, which are in turn limited by the intensity of AMS stable ion beam currents. We present data obtained at the Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratories (LLNL) indicating that AMS ion beam currents are impacted by certain elemental impurities. For (10)Be analysis, the AMS ion beam current is most adversely affected by the presence of titanium (which can be challenging to separate chemically during sample preparation because of its tendency toward stable refractory forms) and aluminum (which can coelute with beryllium during cation exchange chromatography). In order to minimize impurities that suppress AMS ion beam currents, we evaluate, using inductively coupled plasma atomic emission spectroscopy (ICP-AES), a widely used chemical separation protocol involving a multiacid digestion scheme, preseparation elemental analysis, anion exchange chromatography, ad hoc selective precipitation, cation exchange chromatography, and postseparation elemental analysis.

Practice and feedback effects on the confidence-accuracy relation in eyewitness memory.

It has been claimed that the lack of a reliable confidence-accuracy relation in eyewitness memory stems from eyewitnesses' lack of knowledge concerning their relative expertise. Two studies tested this idea by contrasting the effects of practice alone with practice with feedback in three successive eyewitness tests. Experiment 1 tested recall for events, and Experiment 2 used recognition of faces as test materials. Both studies showed that practice alone did not increase the confidence-accuracy relation, but practice with feedback on relative performance produced robust increases in the confidence-accuracy relation. This suggests that lack of calibration is one factor that causes the reported lack of association between confidence and accuracy for eyewitness memory.

The biological activity of selected cyclic dipeptides.

Cyclic dipeptides are widely used as models for larger peptides because of their simplicity and limited conformational freedom. Some cyclic dipeptides have been shown to be antiviral, antibiotic and anti-tumour. The aim of this study was to determine the biological activity of four cyclic dipeptides synthesized in this laboratory: cyclo(L-phenylalanyl-L-prolyl), cyclo(L-tyrosyl-L-prolyl), cyclo(L-tryptophanyl-L-prolyl) and cyclo(L-tryptophanyl-L-tryptophanyl). The enhancement or inhibition of calcium channels in ventricular myocytes from rats and delayed-rectifier potassium channels in ventricular myocytes from guinea-pigs were determined by use of the whole-cell patch-clamp technique. The induction of differentiation in HT-29 cells was assessed by assaying for an increase in the expression of alkaline phosphatase. Antibiotic properties against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilus and Streptococcus sp. were determined by use of the Kirby-Bauer disc-diffusion assay. Results from these assays indicate that the cyclic dipeptides have biological activity in both prokaryotes and eukaryotes. Three of the dipeptides block cation channels in ventricular myocytes and all increase the expression of alkaline phosphatase. All the dipeptides have concentration-dependent antibacterial properties. These results suggest that with increased solubility the cyclic dipeptides might have potential as muscle relaxants, anti-tumour compounds and antibiotics.

Exclusion of the DYT1 locus in a non-Jewish family with early-onset dystonia.

The DYT1 gene on chromosome 9q34 underlies idiopathic torsion dystonia (ITD) in Jewish and non-Jewish families with childhood and adolescent-onset dystonia that usually starts in a limb, spreads to other limbs, and uncommonly involves cranial muscles. We examined 39 members of a Mennonite family of German ancestry in which seven were affected with ITD. Age at onset was 14.7 years (range 5-34 years) and symptoms began in a limb in four. The remaining three had onset in the neck, face, and larynx. Dystonia progressed to involve at least one arm and one leg in all seven and there was cranial involvement in six. Five of these six had moderate or severe speech impairment. Linkage analysis with 9q34 markers excluded the region containing the DYT1 locus in this family. This study suggests that a gene other than DYT1 underlies some cases of early limb-onset ITD. The clinical features of prominent cranial involvement and impaired speech distinguish this "non-DYT1" early-onset ITD family from the typical DYT1 phenotype.

The DYT1 gene on 9q34 is responsible for most cases of early limb-onset idiopathic torsion dystonia in non-Jews.

Idiopathic torsion dystonia (ITD) is characterized by involuntary twisting movements and postures. A gene for this disorder, DYT1, was mapped to chromosome 9q34 in 12 Ashkenazi Jewish (AJ) families and one large non-Jewish kindred. In the AJ population, strong linkage disequilibrium exists between DYT1 and adjacent markers within a 2-cM region. The associated haplotype occurs in > 90% of early limb-onset AJ cases. We examined seven non-Jewish ITD families of northern European and French Canadian descent to determine the extent to which early-onset ITD in non-Jews maps to DYT1. Results are consistent with linkage to the DYT1 region. Affected individuals in these families are clinically similar to the AJ cases; i.e., the site of onset is predominantly in the limbs and at least one individual in each pedigree had onset before age 12 years. None carries the AJ haplotype; therefore, they probably represent different mutations in the DYT1 gene. The two French Canadian families, however, display the same haplotype. Estimates of penetrance in non-Jewish families range from .40 to .75. We identified disease gene carriers and, with adjustments for age at onset, obtained a direct estimate of penetrance of .46. This is consistent with estimates of 30%-40% in the AJ population. Two other non-Jewish families with atypical ITD (later onset and/or cranial or cervical involvement) are not linked to DYT1, which indicates involvement of other genes in dystonia.

Bacterial flora of Tasmanian SIDS infants with special reference to pathogenic strains of Escherichia coli.

The general bacterial flora of 38 Tasmanian SIDS infants was examined together with faecal flora of 134 comparison infants ranging in age from birth to 6 months. The microflora of all specimens received was investigated with special emphasis on the toxigenic Escherichia coli (TEC). Samples were examined for verocytotoxigenic E. coli, free faecal verocytotoxin (FVT), heat labile toxin (LT) and heat stable toxin (ST) producers with the use of a Vero cell assay and commercial kits. The findings of this study revealed a high isolation rate (39%) of TEC from SIDS infants as compared to 1.5% from the healthy comparison infants. Atypical E. coli strains were also identified during the study, including E. coli A-D. An analysis of the same specimens for rotaviral and adenoviral antigens indicated that 30% of the SIDS cases were positive as compared to 20% in the comparison group.

A study of idiopathic torsion dystonia in a non-Jewish family: evidence for genetic heterogeneity.

A gene (DYT1) for idiopathic torsion dystonia (ITD) was mapped to chromosome 9q34 in non-Jewish and Jewish families; the dystonia in these families usually began in childhood, with the limb muscles affected first. The role of the DYT1 gene in adult-onset and cervical- or cranial-onset ITD is unknown. We examined 53 individuals from four generations of a non-Jewish North American family with adult-onset ITD. There were seven affected family members, with a mean age at onset of 28.4 years (range, 7 to 50 years). In six of the seven, the neck was affected first. All seven developed cervical dystonia, and dysarthria or dysphonia occurred in five. Linkage data excluded the region containing the DYT1 locus, indicating that DYT1 was not responsible for ITD in this family. This study provides evidence that a gene other than DYT1 is responsible for some cases of adult cervical-onset dystonia.

The clinical significance of Escherichia coli Alkalescens-Dispar in Tasmania.

An investigation in 1989 of human fecal specimens revealed that of 111 diarrheal samples examined Escherichia coli Alkalescens-Dispar (A-D) were found in 9 (8.1%), but none were isolated from normal stool samples. Further studies have shown that although these isolates may be potential pathogens, they seem to remain unrecognized by routine laboratories due to their biochemical similarity to shigellae, a problem further exacerbated by their extensive sharing of O antigens. All the isolates were screened with an invasive DNA probe and all but three isolates were found to have a common plasmid. They were also confirmed to be invasive in HEp-2 monolayers. No isolates were shown to produce heat-labile or heat-stable toxin but electronmicroscopy revealed the presence of pili. The A-D isolates were biotyped using the two-tier schema of Crichton and Old and were categorized into biotypes 11, 12 and 16. These data confirm the importance of introducing an awareness of this intermediate strain into routine laboratories.

Therapeutic trial of milacemide in patients with myoclonus and other intractable movement disorders.

We performed a therapeutic trial with the glycine precursor, milacemide, on 10 patients with intractable movement disorders. Six had myoclonus of various etiologies and one each had progressive supranuclear palsy, Filipino X-linked dystonia with parkinsonism, painful legs and moving toes, and stiff-person syndrome. Milacemide was initiated at a dose of 2,400 mg/day, orally, and increased gradually to a maximum of 4,800 mg/day. No clear-cut observable improvement occurred. There were no serious adverse effects.

Neuropathology of lubag (x-linked dystonia parkinsonism).

Lubag is an x-linked recessive dystonia parkinsonism that affects Filipino men originating principally from the Panay Island. Linkage analysis has confirmed the mode of inheritance and localized the disease gene to the proximal long arm of the x-chromosome. We studied the brain of a 34 year old Filipino man affected with lubag. He developed truncal dystonia at age 30, which subsequently generalized. With disease progression, he also presented with parkinsonism including, rigidity, bradykinesia, and impaired balance. His symptoms were largely unaffected by medication and, at age 34, he underwent a right cryothalamotomy. He died suddenly 2 days after the procedure. The principal neuropathological findings were neuronal loss and a multifocal mosaic pattern of astrocytosis restricted to the caudate and lateral putamen. Similar findings have been reported in two other men with dystonia--one Filipino and the other non-Filipino. The similar pathology of the two Filipino men suggests that this is the pathology of lubag. Recognition of this pathology in a non-Filipino man suggests that the mutation causing lubag may not be restricted to the Filipino population.

The use of prophylactic eye drops during high-dose cytosine arabinoside therapy.

An ocular toxic reaction presenting as conjunctivitis or keratitis develops in a significant number of patients who are treated with high-dose cytosine arabinoside (ara-C). Although eye drops containing glucocorticoid reportedly decrease the incidence, they do not totally eliminate this side effect. In comparing this technique with artificial tears, both were found to be equally effective. The primary mechanism by which eye drops decrease ocular toxic reactions associated with high-dose ara-C is presumably due to dilution of intraocular concentrations of ara-C.

An investigation of culture media for the isolation of shigellae.

In this study we have investigated the efficiency of presently available culture media for the isolation of shigellae. XLD was found to be the medium of choice, combined with both less and more selective culture media (e.g. MacConkey, and Hektoen or DCA). By using these media in combination it was found that not only were shigellae isolated more often and efficiently, but fewer problems were encountered in isolating other Enterobacteriaceae.

Clinical significance of MRI white matter lesions in the elderly.

The clinical relevance of white matter hyperintensities (WMH) seen on MRIs of elderly individuals is controversial. To resolve this issue, we performed MRI and neuropsychological testing on 46 healthy participants in the longitudinal Aging Process Study at the University of New Mexico. We graded the MRIs for severity of WMH using a scale tested on an elderly patient population. We found that 22% of normal subjects had moderate lesions and 9% had severe lesions. All subjects had normal neurologic examination findings and were within normal limits on a battery of neuropsychological tests. Neuropsychological performance decreased and the severity of WMH increased with age. However, when the data were corrected for age, there was no correlation between neuropsychological function and the presence of WMH. We conclude that white matter changes in the elderly by themselves are of doubtful clinical significance.

Studies on cyclopropane fatty acid synthesis. Effect of carbon source and oxygen tension on cyclopropane fatty acid synthetase activity in Pseudomonas denitrificans.

The cyclopropane fatty acid, methylene hexadecanoic acid, constituted from 1% to upwards of 30% of the total lipid fatty acids of the bacterium, Pseudomonas denitrificans. The amount of this component varied along with the levels of the enzyme, cyclopropane synthetase (unsaturated-phospholipid methyltransferase, EC 2.1.1.16). When P. denitrificans was grown on succinate in a culture medium saturated with oxygen, cyclopropane synthetase remained repressed while cell densities were low. As cell densities increased, the enzyme was induced and the activity rose to a maximum over a period of 4-6 h. Cyclopropane synthetase could also be induced by rapidly limiting the oxygen supply to cells growing in conditions where oxygen was in excess. This phenomenon was independent of the phase of growth and could be prevented by addition of chloramphenicol to the medium. Growth on glucose was also shown to repress the synthesis of cyclopropane synthetase under similar conditions. However, once maximum levels of cyclopropane synthetase were reached, they remained constant for at least the following 15 h irrespective of the source of carbon in the medium. Methylene hexadecanoic acid accumulated in a linear manner throughout this period until a maximum level was achieved, the rate of accumulation being related to the activity of cyclopropane synthetase detected in vitro. The rate of conversion of total fatty acid to methylene hexadecanoic acid was approximately 1.3-1.5% per h, the methylene hexadecanoic acid being metabolically stable - the relative percentage of methylene hexadecanoic acid to total fatty acid in repressed cells, falling linearly with increase in cell number. Repression of enzyme synthesis was further investigated by growing cells on various sources of carbon other than glucose. The results indicated that succinate was unique amongst tricarboxylic acid cycle intermediates in depressing cyclopropane synthetase under limited oxygen conditions.