Human alpha-tocopherol transfer protein: cDNA cloning, expression and chromosomal localization

alpha-Tocopherol transfer protein (alpha TTP), which specifically binds this vitamin and enhances its transfer between separate membranes, was previously isolated from rat liver cytosol. In the current study we demonstrated the presence of alpha TTP in human liver by isolating its cDNA from a human liver cDNA library. The cDNA for human alpha TTP predicts 278 amino acids with a calculated molecular mass of 31,749, and the sequence exhibits 94% similarity with rat alpha TTP at the amino acid level. The recombinant human alpha TTP expressed in Escherichia coli exhibits both alpha-tocopherol transfer activity in an in vitro assay and cross-reactivity to the anti-(rat alpha TTP) monoclonal antibody. Northern blot analysis revealed that human alpha TTP is expressed in the liver like rat alpha TTP. The human and rat alpha TTPs show structural similarity with other apparently unrelated lipid-binding/transfer proteins, i.e. retinaldehyde-binding protein present in retina, and yeast SEC14 protein, which possesses phosphatidylinositol/phosphatidylcholine transfer activity. Both Southern-blot hybridization of human-hamster somatic cell hybrid lines and fluorescence in situ hybridization revealed a single alpha TTP gene corresponding to the 8q13.1-13.3 region of chromosome 8, which is identical to the locus of a recently described clinical disorder, ataxia with selective vitamin E deficiency (AVED). The relationship between alpha TTP and AVED will be discussed.

New markers of remote ischemia in patients with evolving inferior myocardial infarction

Multivessel disease and decreased left ventricular ejection fraction (LVEF) are believed to be significant predictors of the outcome in patients with acute inferior myocardial infarction (AIMI). We attempted to determine new electrocardiographic (ECG) markers for detecting concomitant left anterior descending (LAD) disease and/or decreased left ventricular function in patients with AIMI. Eighty patients with AIMI were evaluated within 6 h of the onset of symptoms and grouped according to the presence (Group 1) or absence (Group 2) of concomitant LAD disease. All of the patients underwent coronary angiography and left ventriculography 4-6 weeks from the onset of their infarction. We studied the validity of two new ECG markers: S-T depression deeper in lead V5 than in V4 (S-T decreases V5 > V4) and negative U waves (NUs) > 0.5 mm (50 muV) in leads V4-6. The sensitivity and specificity of S-T decreases V5 > V4, NUs in V4-6, or both, in detecting concomitant LAD disease were 56% and 83%, 59% and 87%, and 35% and 98%, respectively. LAD lesions in patients who showed either of these new markers (74% of those with S-T decreases V5 > V4 and 80% of those with NUs in V4-6) were mostly in the proximal segments (AHA segments #6 or #7). Patients with either S-T decreases V5 > V4 or NUs in V4-6 tended to have asynergy in the anterolateral segment, while there was a strong correlation between the asynergy of the anterolateral and septal segments in patients who showed both ECG markers.(ABSTRACT TRUNCATED AT 250 WORDS)

Write compensation using the thermal transfer function in an optical disk

The theoretical basis for a write-compensation scheme is developed with a simplified thermal transfer function in an optical disk. The thermal transfer function is analytically approximated to a first-order exponential filter similar to that of an integrating circuit. A write-compensation method is then given directly by the inverse function of the filter. A simplified form of the compensation is also derived, and this is verified by experiments. This method eliminates the thermal interference and shows how to form mark edges uniformly for an arbitrary optical disk.

Action of metalloproteinases on porcine dentin mineralization

Samples containing predentin and mineralized dentin involving the mineralized front (newly formed dentin) were prepared by scraping developing porcine teeth after odontoblastic cell debris had been removed from the predentin surfaces. An extract was obtained separately from the matrices of predentin and of the newly formed dentin with a 4 M guanidine solution before and after demineralization with acetic acid solution. Enzymography detected 56 and 61 kDa gelatinases and 25 kDa proteoglycanase as neutral metalloproteinases in both extracts and proved them to be in an active form. Approximately half of the 56 and 61 kDa gelatinases binds to collagen fibers in predentin matrix. Three high molecular weight proteoglycans (70-85 kDa, 130-180 kDa, and 290 kDa) were found in the predentin matrix, but not in the newly formed dentin. The proteoglycanases in predentin degraded 290 kDa proteoglycan, if incubated together with calcium (Ca) ions. The results of this investigation indicate that active proteoglycanases which existed in the predentin perform no substantial work in proteoglycan degradation because the Ca ions are masked in the predentin matrix by coexisting proteoglycans. When mineralization occurs, however, they can degrade the proteoglycan at the mineralization front because excess Ca ions may be supplied via odontoblastic processes.

Effects of sympathetic stimulation, with and without previous alpha 1 and beta adrenoceptor blockade, on refractoriness dispersion in canine heart

OBJECTIVE

The aim was to determine the electrophysiological effects of cardiac sympathetic stimulation, with and without prior alpha 1 and beta adrenoceptor blockade during myocardial ischaemia in dogs.

METHODS

Chloralose anaesthetised dogs were studied 2 h after ligation of the obtuse marginal branches of the circumflex artery (OMB). The refractory period was measured at eight sites in the ischaemic zone, two sites in the border zone, and two sites in the normal zone with S1-S2 extrastimulus methods.

RESULTS

In group 1 (n = 13), before OMB ligation, stimulation of the ventrolateral cardiac nerve shortened the refractory period only in the ischaemic zone (p < 0.01). OMB ligation resulted in a significant shortening of the refractory period in the ischaemic zone (p < 0.01). In group 2 (n = 12), the alpha 1 blocker bunazosin (0.2 mg.kg-1, intravenously) blunted the shortening of the refractory period in the ischaemic zone induced by OMB ligation (p < 0.01), resulting in a reduction in refractory period dispersion between the ischaemic and non-ischaemic (border and normal) zones. Subsequent administration of the beta blocker propranolol (0.2 mg.kg-1, intravenously) prolonged refractory periods both in the ischaemic and in the non-ischaemic zones (p < 0.05 v p < 0.001). Ventrolateral cardiac nerve stimulation reversed the effects of bunazosin on the refractory period in the ischaemic zone; however, after the addition of propranolol, neural stimulation no longer influenced the refractory period. In group 3 (n = 13), propranolol (0.2 mg.kg-1, intravenously) reversed the shortening of the refractory period in the ischaemic zone (p < 0.01) induced by OMB ligation but also prolonged the refractory period in the non-ischaemic zone (p < 0.001); refractory period dispersion between the ischaemic and non-ischaemic zones was thus not reduced. Ventrolateral cardiac nerve stimulation had no effect on refractory period after administration of propranolol alone or propranolol followed by bunazosin.

CONCLUSIONS

Although an alpha 1 blocker may be better than a beta blocker in reducing refractory period dispersion between the ischaemic and non-ischaemic myocardium, a beta blocker may protect more effectively than an alpha 1 blocker against the detrimental effects of cardiac nerve activity on electrical instability in the ischaemic myocardium.

Evaluation of a nine-lead Holter monitor for identifying and localizing ischemia and coronary artery disease detected by quantitative thallium-201 tomography

We devised a nine-lead Holter monitor system with a lead-switching technique to record electrocardiograms from multiple sites in the anterior and the posterior or lateral chest. Leads CM1 to CM6, high lateral (HL), low lateral (LL), and low posterior chest (LB) were used. The sensitivity, specificity, and predictive accuracy of this system for identifying specific regions of myocardial ischemia and coronary artery disease were investigated in 130 patients with coronary artery disease. Anterolateral leads (CM4 to CM6, HL, and LL) showed high sensitivity for detecting anterior and lateral ischemia (69% to 100%) but low specificity (4% to 44%) compared with tomographic results. The specificity of these leads for identifying single-vessel disease was low (6% to 47%) although some leads showed high sensitivity (69% to 100%). In contrast, the LB lead exhibited high sensitivity and specificity for detecting inferior ischemia (70% and 95%, respectively) and right coronary artery (RCA) disease (74% and 93%, respectively). Consequently, ST depressions in the LB lead (anode) are specific for identifying inferior ischemia and RCA disease, whereas those in the anterior and lateral chest leads do not identify the ischemic region or the obstructed coronary artery.

Heterologous expression of BI Ca2+ channels in dysgenic skeletal muscle

We have examined the ability of BI (class A) Ca2+ channels, cloned from rabbit brain, to mediate excitation-contraction (E-C) coupling in skeletal muscle. Expression plasmids carrying cDNA encoding BI channels were microinjected into the nuclei of dysgenic mouse myotubes grown in primary culture. Ionic currents and intramembrane charge movements produced by the BI channels were recorded using the whole-cell patch-clamp technique. Injected myotubes expressed high densities of ionic BI Ca2+ channel current (average 31 pA/pF) but did not display spontaneous contractions, and only very rarely displayed evoked contractions. The expressed ionic current was pharmacologically distinguished from the endogenous L-type current of dysgenic skeletal muscle (Idys) by its insensitivity to the dihydropyridine antagonist (+)-PN 200-110. Peak BI Ca2+ currents activated with a time constant (tau a) of approximately 2 ms and inactivated with a time constant (tau h) of approximately 260 ms (20-23 degrees C). The time constant of inactivation (tau h) was not increased by substituting Ba2+ for Ca2+ as charge carrier, demonstrating that BI channels expressed in dysgenic myotubes do not undergo Ca(2+)-dependent inactivation. The average maximal Ca2+ conductance (Gmax) produced by the BI channels was quite large (approximately 534 S/F). In contrast, the average maximal charge movement (Qmax) produced in the same myotubes (approximately 2.7 nC/microF) was quite small, being barely larger than Qmax in control dysgenic myotubes (approximately 2.3 nC/microF). Thus, the ratio Gmax/Qmax for the BI channels was considerably higher than previously found for cardiac or skeletal muscle L-type Ca2+ channels expressed in the same system, indicating that neuronal BI Ca2+ channels exhibit a much higher open probability than these L-type Ca2+ channels.

Fully automated flow-injection system for quantifying 1,5-anhydro-D-glucitol in serum

We have developed a flow-injection system with colorimetric detection to measure 1,5-anhydro-D-glucitol in serum. Serum samples are directly and serially injected into a clean-up column every 3.5 min to remove interferences before the enzymatic reaction. 1,5-Anhydro-D-glucitol, after being passed through the column, is oxidized by immobilized pyranose oxidase (EC 1.1.3.10), and the hydrogen peroxide produced reacts with the chromogen substrate in the presence of immobilized horseradish peroxidase (EC 1.11.1.7) to form Bindshedler's Green. The detection limit was 1.2 mumol/L (1.2 pmol). The correlation between results obtained with the present system (y) and gas chromatography-mass spectrometry (GC-MS) (x) in samples containing &lt; 30 mumol/L 1,5-anhydro-D-glucitol, including many samples from patients with diabetes mellitus, was y = 0.975x-0.111 mumol/L (r = 0.997), which was superior to that obtained between the enzymatic and GC-MS methods. Our system needs only to be set up; it runs without any manual pretreatment, assays 17 samples/h, and shows imprecision (CV) of &lt; 2%.

Fully automated flow-injection system for quantifying 1,5-anhydro-D-glucitol in serum

We have developed a flow-injection system with colorimetric detection to measure 1,5-anhydro-D-glucitol in serum. Serum samples are directly and serially injected into a clean-up column every 3.5 min to remove interferences before the enzymatic reaction. 1,5-Anhydro-D-glucitol, after being passed through the column, is oxidized by immobilized pyranose oxidase (EC 1.1.3.10), and the hydrogen peroxide produced reacts with the chromogen substrate in the presence of immobilized horseradish peroxidase (EC 1.11.1.7) to form Bindshedler's Green. The detection limit was 1.2 mumol/L (1.2 pmol). The correlation between results obtained with the present system (y) and gas chromatography-mass spectrometry (GC-MS) (x) in samples containing < 30 mumol/L 1,5-anhydro-D-glucitol, including many samples from patients with diabetes mellitus, was y = 0.975x-0.111 mumol/L (r = 0.997), which was superior to that obtained between the enzymatic and GC-MS methods. Our system needs only to be set up; it runs without any manual pretreatment, assays 17 samples/h, and shows imprecision (CV) of < 2%.

Patch culturing and transfer of human fetal retinal epithelium

Human retinal pigmented epithelium (RPE) can be cultured by removing small patches of this layer from the choroid of the fetal eye. Such RPE patches give rise to healthy, epithelioid monolayers in vitro within 1-2 weeks without contamination from retinal or choroidal cells. The viability and proliferative capacity of these cultures is independent of the initial polarity of the patch. These RPE monolayers develop apical/basal polarity and a basal lamina and rest on a field of collagen fibers; they are capable of phagocytizing outer segments. A patch can be lifted off a confluent monolayer and transferred to another culture dish without risking the viability of either the old or the new culture. This provides a means of transplanting an organized, polarized patch of human RPE from one place to another.

New approach to aortic dissection: development of an insertable aortic prosthesis

We have developed a new aortic prosthesis with which we can replace or reinforce the aorta using a simple percutaneous technique. We have named the new prosthesis the shape-memory aortic prosthesis (SAP); it consists of a spiral-shaped nitinol stent and polyurethane tube. It can be compressed inside a 14F catheter at a low temperature and regain its original shape at above 30 degrees C. As a preliminary study, SAP sutureless grafting into the descending aorta was performed on 10 mongrel dogs. We found that when the proper diameter of SAP was applied, it functioned satisfactorily for 3 months or more. A percutaneous placement technique pertinent to the SAP also was developed and tried on 4 animals. Our procedure was applied to Stanford type B dissection models to close the entry point successfully. This newly developed SAP has potential to be applied to emergency cases of human aortic dissections.

A new type of staphylococcal exfoliative toxin from a Staphylococcus aureus strain isolated from a horse with phlegmon

A new type of staphylococcal exfoliative toxin (sET) was isolated from the culture filtrate of a Staphylococcus aureus strain isolated from a horse with skin infection including phlegmon. The new sET was purified by precipitation with 80% saturated ammonium sulfate, column chromatography on DEAE-cellulofine A-500, gel filtration on a Sephadex G-75 column, and polyacrylamide gel electrophoresis (7.5% polyacrylamide). The new sET elicited general exfoliation of the epidermis with the so-called Nikolsky sign when inoculated into both 3-day-old mice and 1-day-old chicks, whereas sETA and sETB from human strains of S. aureus caused exfoliation in a 3-day-old mouse alone and shET from a porcine strain of Staphylococcus hyicus caused exfoliation in 1-day-old chicks alone. Intraepidermal splitting was observed at the granular layer of the epidermis of mice inoculated with the new sET as well as those inoculated with sETA. Exfoliation at the germinative layer of the epidermis was also observed in the chicks inoculated with the new sET as well as those inoculated with shET. The new sET was serologically different from sETA, sETB, and shET and showed the same molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was thermolabile and lost its toxicity after being heated at 60 degrees C for 15 min. We propose that the new sET be designated as sETC.

Technical approach for reanimation of the chronically denervated larynx by means of functional electrical stimulation

Functional electrical stimulation (FES) of the posterior cricoarytenoid (PCA) muscle to produce vocal fold abduction offers an alternative approach to current surgical therapies for bilateral vocal fold paralysis. The purpose of this study was to characterize the application of FES to chronically denervated PCA muscles. Specific goals were to develop a stimulus delivery system for the PCA muscle, determine a practical means of implantation, and identify stimulus parameters effective in activating chronically denervated muscle. Seventeen dogs were implanted with planar electrode arrays 3 months after unilateral recurrent laryngeal nerve resection. A nail-bed electrode array allowed discrete activation of the PCA muscle and gave the greatest abductions, with minimal charge dissipation. Muscle mapping revealed hot-spot regions on the PCA muscle surface, in which stimulation produced maximum abduction. A conservative stimulus paradigm effective in activating chronically denervated muscle was a 1-second pulse train of 2-millisecond-duration pulses, delivered at a tetanizing frequency of 30 Hz and an amplitude of 4 to 14 mA.

Characterization of the human gene (TBXAS1) encoding thromboxane synthase

The gene encoding human thromboxane synthase (TBXAS1) was isolated from a human EMBL3 genomic library using human platelet thromboxane synthase cDNA as a probe. Nucleotide sequencing revealed that the human thromboxane synthase gene spans more than 75 kb and consists of 13 exons and 12 introns, of which the splice donor and acceptor sites conform to the GT/AG rule. The exon-intron boundaries of the thromboxane synthase gene were similar to those of the human cytochrome P450 nifedipine oxidase gene (CYP3A4) except for introns 9 and 10, although the primary sequences of these enzymes exhibited 35.8% identity each other. The 1.2-kb of the 5'-flanking region sequence contained potential binding sites for several transcription factors (AP-1, AP-2, GATA-1, CCAAT box, xenobiotic-response element, PEA-3, LF-A1, myb, basic transcription element and cAMP-response element). Primer-extension analysis indicated the multiple transcription-start sites, and the major start site was identified as an adenine residue located 142 bases upstream of the translation-initiation site. However, neither a typical TATA box nor a typical CAAT box is found within the 100-b upstream of the translation-initiation site. Southern-blot analysis revealed the presence of one copy of the thromboxane synthase gene per haploid genome. Furthermore, a fluorescence in situ hybridization study revealed that the human gene for thromboxane synthase is localized to band q33-q34 of the long arm of chromosome 7. A tissue-distribution study demonstrated that thromboxane synthase mRNA is widely expressed in human tissues and is particularly abundant in peripheral blood leukocyte, spleen, lung and liver. The low but significant levels of mRNA were observed in kidney, placenta and thymus.

The cyclic AMP response element plays an essential role in the expression of the human prostaglandin-endoperoxide synthase 2 gene in differentiated U937 monocytic cells

The promoter activity of 1432 bp upstream of the human prostaglandin-endoperoxide synthase 2 gene (PTGS2) was examined in differentiated U937 monocytic cells expressing prostaglandin-endoperoxide synthase 2 mRNA. Transient transfection experiments were performed using these cells and reporter vectors containing the upstream region of the gene with deletions or site-specific mutations and the luciferase gene. The deletion or destruction of the cyclic AMP response element (nucleotides -59 to -53) markedly reduced the promoter activity of this gene. Electrophoretic mobility shift assays showed that a nuclear protein(s) binding to the cyclic AMP response element was induced during monocytic differentiation of U937 cells. These results indicate that expression of the human prostaglandin-endoperoxide synthase 2 gene in differentiated U937 monocytic cells is regulated by the cyclic AMP response element.