Spatiotemporal measurement of free radical elimination in the abdomen using an in vivo ESR-CT imaging system

Electron spin resonance (ESR) imaging can visualize the distribution of free radicals in living systems according to their concentrations. However, the application of ESR imaging to living animals has not been well established. Using a rapid field scan L-band ESR imaging system, we have successfully obtained two-dimensional ESR projection (xz-plane projection) and three-dimensional ESR-CT (trans-axial section along the y-axis) images of the abdomen of living mice after an injection of 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (carbamoyl-PROXYL) into the tail vein. The in vivo two-dimensional ESR projection imaging clearly visualized the carbamoyl-PROXYL distribution and the rapid decay process in the abdomen. Because among the viscera, the liver is most abundantly associated with a blood volume, the outline of the image can be composed mainly of this organ. We therefore attempted to find whether there will be a difference in spatiotemporal dynamics of carbamoyl-PROXYL in the abdomens between the control and the mice with liver damage by two-dimensional ESR projection. In the control mice, carbamoyl-PROXYL was almost completely eliminated from the abdomen within 5 minutes after administration. On the other hand, in mice with carbon tetrachloride-damaged livers, the decay of carbamoyl-PROXYL was markedly prolonged. Even at 5 min after administration, carbamoyl-PROXYL remained clearly visible in the abdomen. In vivo three-dimensional ESR-CT imaging showed an even distribution of carbamoyl-PROXYL throughout the whole liver, which corresponded well with the images of trans-axial sections of the murine abdomen. We have succeeded in displaying two-dimensional ESR projection and three-dimensional ESR-CT images of carbamoyl-PROXYL distribution and clearance in the abdomen of a living animal. The ESR-CT imaging technique is considered to be a powerful new tool for noninvasive investigations of the in vivo spatiotemporal dynamics of free radical distribution and elimination in the organs.

Two types of differentially photo-regulated nuclear genes that encode sigma factors for chloroplast RNA polymerase in the red alga Cyanidium caldarium strain RK-1

A nuclear gene, sigA, that encodes a sigma factor for chloroplast RNA polymerase has previously been identified and characterized in the primitive red alga Cyanidium caldarium strain RK-1. Southern hybridization analysis indicated the presence of two additional sigma factor genes, which have now been cloned and shown to encode virtually identical proteins that are homologous to eubacterial sigma factors. These genes, which are also present in the nuclear genome, have therefore been named sigB and sigC. The substantial sequence similarity of sigB and sigC to sigA of the same strain as well as to cyanobacterial principal sigma factors and other chloroplast sigma factors strongly suggests that the nuclear genome of C. caldarium contains three genes that encode two types of chloroplast sigma factors. Each of the three recombinant Sig proteins showed sigma factor activity in vitro when combined with the Escherichia coli RNA polymerase core enzyme. Northern blot analysis revealed that, whereas the overall abundance of sigA transcripts was not affected by light, the amount of sigB and sigC mRNAs was greater in the light than in the dark. Thus, multiple sigma factors appear to contribute to light-regulated gene expression in the chloroplast.

Gain characteristics of tellurite-based erbium-doped fiber amplifiers for 1.5-microm broadband amplification

The signal-gain characteristics of tellurite-based erbium-doped fiber amplifiers are clarified based on spectroscopic properties and signal-gain measurements. The potential of tellurite-based erbium-doped fiber for use as a broadband light source is also described.

Productive interactions between the two domains of pig heart CoA transferase during folding and assembly

The enzyme CoA transferase from porcine heart (EC 2.8.3.5) is a homodimer; each subunit consists of two domains linked by a hydrophilic "hinge" region. We have prepared separate DNA segments encoding each of these domains. Incorporation of these two DNA segments within an operon or within two separate transcription units does not preclude the synthesis and assembly of CoA transferase in Escherichia coli. When the two domain fragments are produced and purified individually from separate cultures and subsequently mixed, enzyme activity accumulates to near wild-type levels only after a lengthy incubation. Each domain is more susceptible to aggregation than wild-type CoA transferase. Circular dichroism shows that, prior to mixing, the domains possess a different secondary structural profile compared to their counterparts in the native enzyme. However, mixing and incubation of the domains produces a complex with far-UV CD, fluorescence, and ultracentrifugation properties similar to those of wild-type CoA transferase. Finally, we show that the intact hydrophilic peptide which links the two domains is essential for the recovery of activity observed upon refolding of the denatured enzyme in vitro. These results indicate that the folding and assembly of pig heart CoA transferase require a productive interaction between its two domains, involving a substantial conformational rearrangement.

[Psychosocial support to improve quality of life (QOL) in home terminal carcinoma patients]

There are numerous psychosocial problems with home care for terminal cancer patients. We studied one case from the viewpoint of providing support for cancer patients and their families. Psychosocial problems are important for the life of cancer patients and their families. The cancer diagnosis and the terminal stage have different levels of psychosocial concerns. We must consider effective intervention with such psychosocial support. (1) The team delivery of health care in oncology is more crucial than ever. (2) Social work plays a key role. (3) We should strive to understand the roles of other members of teams. (4) Members of a support team should take turns in providing care according to the psychosocial conditions of the patients. (5) Sympathy and a broad social outlook are required of medical staff members.

[Assistance to enhance the use of home helper services for the cancer patient]

For the end-stage cancer patient to live at home with his or her quality of life (QOL) sustained, Home Helper Services are considered effective. In fact, however, many do not avail themselves of such services. Since the disease situation is apt to change dramatically, it is difficult to predict the length of time of care at home, and the patient's family does not tend to utilize such services unless the patient is completely bedridden. Short-term use or the difficulty or rapid response of such services has been among the reasons given of this. Given this background, there appears to be a need for suitable assessment in dealing quickly with possible disabilities which might occur and a number of occupations. Also, when considering home medical care for the cancer patient, an administrative system capable of a rapid response when problems of this kind occur is indispensable. Working on the administration to fulfill this need is also the task of the professionals in this field.

A 3D- and 4D-ESR imaging system for small animals

A new version of in vivo ESR-CT system composed of custom-made 0.7 GHz ESR spectrometer, air-core magnet with a field-scanning coil, three field-gradient coils, and two computers enables up- and down-field, and rapid magnetic-field scanning linearly controlled by computer. 3D-pictures of distribution of nitroxide radicals injected in brains and livers of rats and mice were obtained in 1.5 min with resolution of 1 mm. We have also succeeded in obtaining spatial-time imagings of the animals.

Fluorescence studies of lipid association-induced conformational adaptations of an exchangeable amphipathic apolipoprotein

The conformational adaptability of Manduca sexta apolipophorin III (apoLp-III) has been evaluated by monitoring the spectroscopic properties of its sole tyrosine residue, Tyr145, present in the fifth helical segment of the protein. M. sexta apoLp-III adopts a globular five-helix bundle structure in solution and has been postulated to undergo an opening at putative hinge domains upon interaction with lipid surfaces. Previous results have shown that the intrinsic fluorescence of Tyr145 is highly quenched in the closed, water-soluble conformation but is dramatically enhanced upon lipid association. We have carried out a spectroscopic characterization of Tyr145 and its microenvironment, to enable its use as a structural probe of lipid-induced conformational changes of apoLp-III. The pKa of Tyr145 in lipid-free apoLp-III was found to be 10.5, as determined from uv-spectrophotometry, indicating that, in the ground state, the tyrosyl phenolic group is not ionized under physiological conditions. Compared to free tyrosine in aqueous buffer (pH 7.0), a red shift (77 nm) in the (lambda)max of absorbance of Tyr145 was observed, suggesting that an H-bonding interaction is responsible for the quenched state of tyrosine fluorescence. In an effort to explain the observed quenching phenomenon, the quantum yield and lifetimes of Tyr145 fluorescence emission were investigated as a function of pH and lipid binding. The quantum yield of Tyr145 in lipid-free apoLp-III was enhanced fivefold upon decreasing the pH, with a half-maximal point around pH 5.5. Time-resolved fluorescence decay analysis showed that Tyr145 exhibits nonexponential emission decay with two components having lifetimes of 3.3 ns (76%) and 0.89 ns (24%) in the lipid-free state. The lifetime and amplitude of Tyr145 remain essentially unaltered upon lipid association or decreasing the pH. This is consistent with the hypothesis that, in the lipid-free helix bundle conformation, a quenching residue exists within H-bonding distance of the phenolic side chain of Tyr145 which, at physiological pH, is responsible for the observed fluorescence quenching. Opening of the helix bundle repositions this acceptor base, possibly a carboxylate or an imidazole side chain, making it unavailable for quenching. Using differential polarized phase and modulation fluorometry, it was seen that the segmental motion of Tyr145 is also altered considerably upon lipid interaction. These spectroscopic and motional properties of Tyr145 distinguish this unique residue as a useful probe to monitor structural flexibility of apoLp-III.

The consequences of engineering an extra disulfide bond in the Penicillium camembertii mono- and diglyceride specific lipase

The extracellular lipase from Penicillium camembertii has unique substrate specificity restricted to mono- and diglycerides. The enzyme is a member of a homologous family of lipases from filamentous fungi. Four of these proteins, from the fungi Rhizomucor miehei, Humicola lanuginosa, Rhizopus delemar and P. camembertii, have had their structures elucidated by X-ray crystallography. In spite of pronounced sequence similarities the enzymes exhibit significant differences. For example, the thermostability of the P. camembertii lipase is considerably lower than that of the H. lanuginosa enzyme. Since only the P. camembertii enzyme lacks the characteristic long disulfide bridge, corresponding to Cys22-Cys268 in the H. lanuginosa lipase, we have engineered this disulfide into the former enzyme in the hope of obtaining a significantly more stable fold. The properties of the double mutant (Y22C and G269C) were assessed by a variety of biophysical techniques. The extra disulfide link was found to increase the melting temperature of the protein from 51 to 63 degrees C. However, no difference is observed under reducing conditions, indicating an intrinsic instability of the new disulfide. The optimal temperature for catalytic activity decreased by 10 degrees C and the optimum pH was shifted by 0.7 units to more acidic.

In vivo EPR detection and imaging of endogenous nitric oxide in lipopolysaccharide-treated mice

Nitric oxide (NO), a simple diatomic free radical, is known to play a critical physiological role in diverse organisms. An iron complex, with N-(dithiocarboxy)sarcosine (Fe-DTCS), has a high affinity for endogenous NO and can trap, stabilize, and accumulate it. The stable NO adduct thus formed is detectable at room temperature with electron paramagnetic resonance (EPR) spectrometry. We report in vivo EPR imaging of endogenous NO, trapped by an Fe-DTCS complex, in the abdomen of a live mouse. To our knowledge, this is the first report on EPR imaging of endogenous free radicals produced in vivo. This EPR imaging method will be useful for the noninvasive investigation of the spatial distribution of NO in pathologic organs or tissues.

Nuclear encoding of a chloroplast RNA polymerase sigma subunit in a red alga

A chloroplast RNA polymerase sigma factor is encoded by a nuclear gene, sigA, in the red alga Cyanidium caldarium RK-1. The encoded protein functions as an RNA polymerase sigma factor in vitro and it is localized to the chloroplast in vivo. SigA shows high sequence similarity to the sigma factors of cyanobacteria, which is indicative of the ancestral endosymbiotic event and subsequent transfer of the sigA gene to the nuclear genome.

Free radical imaging by electron spin resonance computed tomography in rat brain

Images of nitroxide radicals were obtained from the brains of living rats following intracarotid injection of imaging agent, [2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinylox y] (16 DS) using L-band electron spin resonance computed tomography (ESR-CT). The image patterns obtained from the 3-carbamoyl-2,2,5,5-tetramethyl-1-pyrrolinyloxy injected rats showed the agent in tissues of the cranium but not within the brain. The uptake of 16 DS was found in the cortex, hippocampus, striatum, midbrain, pons medulla oblongata and cerebellum, and nuclei, mitochondria, synaptosomes of the cerebrum after intracarotid injection of 16 DS using an x-band ESR spectrometer. These results suggest that 16 DS penetrates the blood brain barrier.

Hepatitis E probably contracted via a Chinese herbal medicine, demonstrated by nucleotide sequencing

Hepatitis E is endemic in developing countries and may occur as imported hepatitis in industrialized countries. A 46-year-old Japanese man developed immunoserologically diagnosed acute hepatitis E in Japan 4 months after he had made a trip to China. He had bought a Chinese herbal medicine there, taking it occasionally until approximately 6 weeks prior to the onset of acute hepatitis. Nucleotide sequencing of the 3' terminal region of the viral cDNA amplified from the patient's serum by polymerase chain reaction revealed a high degree of homology (99.8% of 752 nucleotides) with the Chinese strain. Thus, the results of sequencing suggest that his hepatitis E was caused by infection with the Chinese strain, via the Chinese herbal medicine.

[Free radical generation in electron transport system of mitochondria after cold preservation in UW solution]

In the liver transplantation one of the causes of primary graft nonfunction is likely associated with lipid peroxidation at reperfusion after cold preservation. In this study, we investigated whether free radicals produced in mitochondrial electron transport system would result in lipid peroxidation after cold preservation in UW solution.

MATERIALS AND METHODS

Under anesthesia, the liver of male Wistar rat was flushed via the portal vein with cold Ringer lactate, and then placed in 4 degrees C UW solution for 24 hr. After cold preservation, we examined mitochondrial respiratory control ratio (RCR), free radicals (O2-) from mitochondrial electron transport system by MCLA induced chemiluminescence, and lipid peroxidation by chemiluminescence (CL) after reoxygenation.

RESULTS

RCR gradually decreased up to 24 hr preservation. O2- generation from mitochondrial electron transport system was not recognized at any length of the time after cold preservation up to 24 hr. At 6 hr, CL values were slightly higher than those of the control, but significantly decreased at 24 hr.

CONCLUSION

O2(-)-generated in electron transport system of mitochondria did not increase with cold preservation up to 24 hr, therefore, the radical from mitochondria did not cause a lipid peroxidation at reperfusion injury.

Bacterial expression and site-directed mutagenesis of a functional recombinant apolipoprotein

To facilitate structure-function studies of Manduca sexta apolipophorin III (apoLp-III), its nucleotide coding sequence was cloned from a fat body cDNA library by in vitro DNA amplification. The amplification product was cloned in the pET expression vector and introduced into E. coli. After induction, cultures were screened for apoLp-III protein production by immunoblotting with anti-apoLp-III serum. Data obtained indicated the presence of apoLp-III in both cell lysates and media of cell cultures harboring the apoLp-III-pET construct but not in cells containing the parent vector. The protein was isolated from the cell-free supernatant of cultures grown in minimal media 4 h after induction. Verification that the recombinant protein produced was indeed apoLp-III was obtained by electrospray mass spectrometric analysis. Circular dichroism (CD) spectroscopy of the isolated recombinant protein revealed a characteristic content of alpha-helical secondary structure with a further induction of helix upon addition of 50% trifluoroethanol. In urea denaturation studies, monitored by CD, evidence was obtained that recombinant and natural apoLp-III possess indistinguishable thermodynamic properties. In addition, lipid binding assays revealed that recombinant apoLp-III formed stable complexes with phospholipids and was capable of associating with lipoprotein surfaces. Examination of the fluorescence properties of recombinant apoLp-III revealed the presence of a noncovalently associated fluorescent contaminant that was effectively removed by reverse phase HPLC.(ABSTRACT TRUNCATED AT 250 WORDS)

The properties of specific binding site of 125I-radioiodinated myotoxin a, a novel Ca++ releasing agent, in skeletal muscle sarcoplasmic reticulum

It was found that myotoxin a (MYTX), which is isolated from prairie rattlesnakes (Crotalus viridis viridis), is a powerful Ca++ releaser in the heavy fraction of sarcoplasmic reticulum (HSR). 125I-labeled MYTX (125I-MYTX), which has high Ca(++)-releasing ability, was successfully prepared. It specifically bound to a single class of binding sites in HSR with a KD of 0.4 microM and Bmax of 6 nmol/mg of protein. 125I-MYTX binding was markedly inhibited by Na+ and K+, whereas it was little affected by Ca++ and Mg++. The binding activity was markedly decreased by spermine, a blocker of Ca++ releasing channels, and was not affected by the other modulators of Ca++ release such as caffeine, procaine or ruthenium red. Spermine decreased the binding in a concentration-dependent manner with the IC50 value of 20 microM. Scatchard analysis of 125I-MYTX binding indicated that the Bmax value was decreased by spermine, although the KD value was not changed, which indicates a noncompetitive mode of inhibition. 125I-MYTX did not bind to the purified ryanodine receptor. Ca++ electrode experiments indicated that MYTX induced Ca++ release from HSR at doses of 0.1 microM or more; this was abolished by spermine. The maximal response to MYTX (10 microM) was further increased by caffeine (10 mM) in 45Ca++ release, which probably indicates that the effects of MYTX and caffeine are synergistic in Ca(++)-releasing action. These results suggest that MYTX binds to an important regulatory protein of Ca++ release, which is not the ryanodine receptor.