Assembly of the antifreeze glycoprotein/trypsinogen-like protease genomic locus in the Antarctic toothfish Dissostichus mawsoni (Norman).

To investigate the genomic architecture underlying the quintessential adaptive phenotype, antifreeze glycoprotein (AFGP) that enables Antarctic notothenioid survival in the frigid Southern Ocean, we isolated the AFGP genomic locus from a bacterial artificial chromosome library for Dissostichus mawsoni. Through extensive shotgun sequencing of pertinent clones and sequence assembly verifications, we reconstructed the highly repetitive AFGP genomic locus. The locus comprises two haplotypes of different lengths (363.6 kbp and 467.4 kbp) containing tandem AFGP, two TLP (trypsinogen-like protease), and surprisingly three chimeric AFGP/TLP, one of which was previously hypothesized to be a TLP-to-AFGP evolutionary intermediate. The ~100 kbp haplotype length variation results from different AFGP copy number, suggesting substantial dynamism existed in the evolutionary history of the AFGP gene family. This study provided the data for fine resolution sequence analyses that would yield insight into the molecular mechanisms of notothenioid AFGP gene family evolution driven by Southern Ocean glaciation.

Induction of periodontal disease via retentive ligature, lipopolysaccharide injection, and their combination in a rat model.

Periodontitis is a highly prevalent, chronic immune-inflammatory disease of the periodontium that results in the periodontium and alveolar bone loss's progressive destruction. In this study, the induction of periodontal disease via retentive ligature, lipopolysaccharide, and their combination at three different times were compared in a rat model. Seventy-two Sprague Dawley rats were distributed into four treatment groups: 1) control group with no treatment; 2) application of 4/0 nylon ligature around second maxillary molars; 3) combination of ligature and LPS injection (ligature-LPS); 4) intragingival injection of Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) to the palatal mucosa of the second maxillary molars. Six rats were sacrificed from each group after 7, 14, and 30 days of periodontal disease induction. Alveolar bone loss, attachment loss, number of inflammatory cells, and blood vessels were evaluated histologically. A micro-CT scan was used as a parameter to know the rate of alveolar bone loss. Parametric data were analyzed using two-way ANOVA followed by Bonferroni correction with a significance set at 5%. Non-parametric data were analyzed using Kruskal-Wallis, followed by multiple comparisons with Bonferroni correction. The histological results revealed significant destructive changes in the periodontal tissues and alveolar bone following the ligature and ligature-LPS induction techniques. These changes were evident as early as seven days, maintained until 14 days post-treatment, and declined with time. The ligature technique was effective in inducing acute periodontal disease. The LPS injection technique did not induce alveolar bone loss, and its combination to ligature added insignificant effects.

Controlling Liquid-Liquid Phase Separation of Cold-Adapted Crystallin Proteins from the Antarctic Toothfish.

Liquid-liquid phase separation (LLPS) of proteins is important to a variety of biological processes both functional and deleterious, including the formation of membraneless organelles, molecular condensations that sequester or release molecules in response to stimuli, and the early stages of disease-related protein aggregation. In the protein-rich, crowded environment of the eye lens, LLPS manifests as cold cataract. We characterize the LLPS behavior of six structural γ-crystallins from the eye lens of the Antarctic toothfish Dissostichus mawsoni, whose intact lenses resist cold cataract in subzero waters. Phase separation of these proteins is not strongly correlated with thermal stability, aggregation propensity, or cross-species chaperone protection from heat denaturation. Instead, LLPS is driven by protein-protein interactions involving charged residues. The critical temperature of the phase transition can be tuned over a wide temperature range by selective substitution of surface residues, suggesting general principles for controlling this phenomenon, even in compactly folded proteins.

C(60) and water-soluble fullerene derivatives as antioxidants against radical-initiated lipid peroxidation.

C(60), vitamin E, and three C(60) derivatives (polar 1 and water-soluble C(3)/D(3)C(60)s) were examined for their antioxidant effects on prevention of lipid peroxidation induced by superoxide and hydroxyl radicals. The protection effect on lipid peroxidation was found to be in the sequence: C(60) >/= vitamin E > 1 > none, for liposoluble antioxidants, and C(3)C(60) >> D(3)C(60) > none, for water-soluble ones. Fluorescence quenching of PyCH(2)COOH (Py = pyrene) by both C(3)- and D(3)C(60)s shows that the Stern-Volmer constant, K(SV), is about the same for both quenchers in aqueous solution. Upon addition of liposomes, the fluorescence quenching becomes more efficient: 5-fold higher in K(SV) for C(3)C(60) than for D(3)C(60). When Py(CH(2))(n)()COOH (n = 1, 3, 5, 9, or 15) was incorporated in lipid membranes, the K(SV)s all were small and nearly equal for D(3)C(60) but were quite large and different for C(3)C(60) with the sequence: n = 1 < 3 < 5 < 9 < 15. The better protection effect of C(3)C(60) on lipid peroxidation than that of D(3)C(60) is attributed to its stronger interaction with membranes. Overall, the antioxidation abilities of the compounds examined were rationalized in terms of the number of reactive sites, the location of antioxidant in lipid membranes, and the strength of interactions between antioxidants and membranes.

Stresses at the cervical lesion of maxillary premolar--a finite element investigation.

OBJECTIVES: The objective of this study was to use a three-dimensional (3-D) finite element model to investigate normal stress distribution to substantiate the tooth flexure mechanism. The study also compared the changes in the stresses by different occlusal loading sites and directions. METHODS: The 3-D finite element analysis was used. A maxillary premolar was selected to construct the simulation model. The model was constructed step-by-step for convergence and validity. Seven load conditions for various load sites and different directions were simulated to the model. RESULTS: The maximal principal stress and minimal principal stress distributions developed within the structures of seven load conditions were output and their stress distributions on z-plane at the vertical midline were shown. The peak tensile stress of the cervical area for various load conditions were compared and listed. CONCLUSIONS: This study has shown that the presence of tensile stresses in the cervical region of a maxillary premolar by various loading sites and different directions. The results coincided with the stress-induced theory, hence sustaining it. The relationship of the affected factors of leverage to the development of cervical abfraction lesions, was explored.

Statistical and parametric analysis of beta-2-microglobulin removal from uremic patients in high flux hemodialysis.

Beta-2-microglobulin (beta 2M) associated amyloidosis has been seen in patients with chronic renal failure after long-term hemodialysis. However, the exact mechanism of beta 2M formation and accumulation is not clinically understood. In this investigation, the formation and removal kinetics of beta 2M were studied by compartmental modeling of a patient dialyzer system. Statistical and parametric analyses of model equations, coupled with clinical data from selected patients, enabled us to predict the behavior and influence of membrane materials upon the clearance characteristics of beta 2M during and between hemodialysis treatments.

Cardiac dysrhythmias with midazolam sedation.

A randomized cross-over study was made of 32 young healthy Hong Kong Chinese to compare the incidence and nature of dysrhythmias that occurred during third molar surgery done under local anesthesia, alone or supplemented with midazolam sedation. The incidence of dysrhythmias during surgery was not significantly different during the two procedures. However prior to surgery, 25% of the patients had dysrhythmias during sedation with midazolam. The majority of dysrhythmias were infrequent unifocal ventricular ectopics. During sedation with midazolam it may be beneficial to monitor the electrocardiogram, especially in high risk patients such as those suffering from ischaemic heart disease, cardiomyopathy, and those on antidysrhythmic drugs.

Molecular diversity and genomic organisation of the alpha, beta and gamma eye lens crystallins from the Antarctic toothfish Dissostichus mawsoni.

The eye lens of the Antarctic toothfish living in the -2 degrees C Southern Ocean is cold-stable. To investigate the molecular basis of this cold stability, we isolated, cloned and sequenced 22 full length crystallin cDNAs. We found two alpha crystallins (alphaA, alphaB), six beta crystallins (betaA1, betaA2, betaA4, betaB1, betaB2, betaB3) and 14 gamma crystallins (gammaN, gammaS1, gammaS2, gammaM1, gammaM3, gammaM4, gammaM5, gammaM7, gammaM8a, gammaM8b, gammaM8c, gammaM8d, gammaM8e, and gammaM9). Alignments of alpha, beta and gamma with other known crystallin sequences indicate that toothfish alpha and beta crystallins are relatively conserved orthologues of their vertebrate counterparts, but the toothfish and other fish gammaM crystallins form a distinct group that are not orthologous to mammalian gamma crystallins. A preliminary Fingerprinted Contig analysis of clones containing crystallin genes screened from a toothfish BAC library indicated alpha crystallin genes occurred in a single genomic region of ~266 kbp, beta crystallin genes in ~273 kbp, while the gamma crystallin gene family occurred in two separate regions of ~180 and ~296 kbp. In phylogenetic analysis, the gammaM isoforms of the ectothermic toothfish displayed a diversity not seen with endothermic mammalian gamma crystallins. Similar to other fishes, several toothfish gamma crystallins are methionine-rich (gammaM isoforms) which may have predisposed the toothfish lens to biochemically attenuate gamma crystallin hydrophobicity allowing for cold adaptation. In addition to high methionine content, conservation of alphabeta crystallins both in sequence and abundance suggests greater functional constraints relative to gamma crystallins. Conversely, reduced constraints upon gamma crystallins could have allowed for greater evolutionary plasticity resulting in increased polydispersity of gamma crystallins contributing to the cold-stability of the Antarctic toothfish lens.

Serotonin-independent model of cisplatin-induced emesis in the ferret.

para-Chlorophenylalanine (PCPA, 100-200 mg/kg) was used as a pharmacological tool to characterize the 5-hydroxytryptamine (5-HT) involvement in the emesis occurring 24 hr after the administration of cisplatin (10 mg/kg) in the ferret. PCPA was effective to antagonize the initial 8 hr period of retching and vomiting, but potentiated the emesis that occurred during the remaining 8- to 24-hr observation period. Tissue samples removed from the brainstem at 24 hr post injection of cisplatin alone revealed an elevation of 5-HT, dopamine and homovanillic acid that was antagonized by the injection of PCPA. Cisplatin also induced increases in the urinary levels of 5-hydroxyindoleacetic acid that was similarly antagonized by PCPA. Results are discussed in terms of the relevance of 5-HT to the model of cisplatin (10 mg/kg)-induced emesis in the ferret compared to the problem of acute and delayed emesis in man. The residual or delayed phase of cisplatin-induced emesis may involve a 5-HT-independent mechanism.

'Leopard' syndrome.

'Leopard' syndrome is a rare inherited disorder associated with a high prevalence of cardiac abnormalities. General anaesthesia for dental treatment in a patient who had cardiomyopathy and bizarre electrocardiographic abnormalities associated with this syndrome is described. A thorough cardiac assessment is advised in a patient with multiple lentigines, although no clinical symptoms or signs may be found. Even if no cardiac abnormality is found before it is better to re-assess the patient, since abnormalities may develop later. The assessment should be repeated if any abnormality was detected before but without clinical significance, since the disease is progressive and may progress more rapidly in some patients than in others.

Clinical experience and model analysis on beta-2-microglobulin kinetics in high-flux hemodialysis.

Beta-2-microglobulin (beta 2M) is associated with amyloidosis. The study of beta 2M kinetics can provide information on the elimination of this uremic toxin. A beta 2M kinetic model modified from Gotch, considering the volume changes between intracellular, interstitial, and intravascular compartments and the generation stimulation and inhibition during hemodialysis is proposed. The clinical experiments on 8 stable hemodialysis patients treated with polysulfone (F80) and polymethyl methacrylate (PMMA, BK2.1p) 3 times a week were conducted. There was an 18% decrease of beta 2M clearance in the period from 30 to 180 min with a time-averaged beta 2M clearance of 48 ml/min using polysulfone dialyzers (F80). In PMMA dialyzers, there was a 64% decrease of beta 2M clearance from 30 to 180 min with a time-averaged clearance of 56.3 ml/min. During hemodialysis, the generation rate was 0.379 mg/min in polysulfone and 0.828 mg/min in PMMA dialyzers. There was a stimulation generation of 0.309 mg/min in polysulfone and 0.749 mg/min in PMMA during hemodialysis. In conclusion, we provide a beta 2M kinetic model including volume changes, polymerization, generation stimulation, and inhibition that is similar to the human physiological condition. This model can be used for further clinical study.