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PubMed1995

Laparoscopic bilateral pelvic and paraaortic lymph node sampling: an evolving technique.

OBJECTIVE: Reports describing laparoscopic lymph node sampling in patients with gynecologic malignancies have yet to describe a method to sample left-sided aortic lymph nodes that has been successful in a large series of patients. We submit our experience with evolving techniques that allow for excellent visualization and resection of both left and right aortic and pelvic lymph nodes. STUDY DESIGN: Forty patients with gynecologic malignancies underwent laparoscopy for surgical staging. Thirty-five of the patients were completely staged laparoscopically with minimal blood loss. The average number of lymph nodes sampled was 27.7 (range 14 to 35). RESULTS: Five patients required laparotomy, two to control bleeding, two to remove unsuspected intraabdominal disease, and one because of equipment failure. Four patients were rehospitalized within 30 days of surgery, two with small bowel obstructions resulting from herniation of the intestine through 12 mm trocar sites and two others with deep vein thromboses. CONCLUSION: These preliminary results demonstrate an ability to complete surgical staging in patients with gynecologic malignancies by means of specific endoscopic techniques. However, there remains a need for continued evaluation of these techniques and the associated morbidities.

Aorta↗
PubMed1986

Functional linkage between phycobilisome and reaction center in two phycobilisome oxygen-evolving photosystem II preparations isolated from the thermophilic cyanobacterium Synechococcus sp.

Photosystem II oxygen-evolving preparations with attached phycobilisomes were isolated from the thermophilic cyanobacterium Synechococcus sp. with beta-octylglucoside or digitonin. Fluorescence emission spectra of the two preparations determined at 77 K largely lacked a far red band which originates from photosystem I. The spectrum of the digitonin preparation was otherwise similar to that of intact cells, whereas the beta-octylglucoside preparation showed a pronounced band at 687 nm, which is considered to be emitted from phycobilisomes. The relative yield of phycobilin fluorescence was similar between the digitonin preparations and the cells but was considerably larger in the beta-octylglucoside preparations at room temperature. The quantum yield of ferricyanide photoreduction determined with light which is absorbed mainly by phycobiliproteins was 0.85 for the digitonin preparation and 0.57 for the beta-octylglucoside preparation. The results indicate that excitation energy is transferred from phycobilisomes to photosystem II reaction centers in the digitonin preparation as efficiently as in intact cells, while a significant portion of light energy harvested by phycobilisomes is not utilized by the primary photochemistry in the beta-octylglucoside preparation. Digitonin and beta-octylglucoside preparations had 65 and 48 chlorophyll a molecules per photosystem II reaction center, respectively. The beta-octylglucoside preparation contained twice as much phycocyanin and allophycocyanin per photosystem II reaction center as the digitonin preparation, which has a phycobiliprotein-to-photosystem II reaction center ratio very similar to that of cells. It is concluded that whereas the beta-octylglucoside preparation contains a considerable amount of free phycobilisomes, all phycobilisomes present in the digitonin preparation are physically and functionally linked to photosystem II reaction center complexes.

Cell Fractionation↗
PubMed1987

Photoreduction of QA, QB, and cytochrome b-559 in an oxygen-evolving photosystem II preparation from the thermophilic cyanobacterium Synechococcus sp.

Light-induced absorption changes in an oxygen-evolving photosystem II (PS II) preparation from the thermophilic cyanobacterium Synechococcus sp. were analyzed using continuous illumination which caused the reduction of both QA (first stable quinone electron acceptor) and QB (second quinone electron acceptor of photosystem II). In this photosystem II preparation in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) the amount of QA was estimated to be 1 per 42 chlorophylls. In the absence of DCMU, plastoquinone (1.68 per QA) was photoreduced to plastohydroquinone within a few seconds, indicating that QB is reduced and protonated during this period. An electrochromic band shift centered around 685 nm was observed with and without DCMU. The extent of this band shift caused by QB reduction per electron was about a third or half of that caused by QA reduction. A significant amount of cytochrome b-559 (0.86 per QA) was photoreduced. Only 60% of the photoreduction of cytochrome b-559 was inhibited by a DCMU concentration that inhibited electron transfer beyond QB, indicating that the site of the reduction of cytochrome b-559 is located before the QB site and possibly on the donor side of PS II.

Chlorophyll↗
PubMed1987

Modification of the properties of S2 state in photosynthetic O2-evolving center by replacement of chloride with other anions.

Properties of the S2 state formed in photosystem II membranes in which Cl- had been replaced by various anions were investigated by means of thermoluminescence measurements and low temperature EPR spectroscopy. The Br--substituted membranes showed the normal thermoluminescence B-band arising from S2Q-B charge recombination, whereas the SO2-4-, F--, CH3COO--, and NO-3-substituted membranes showed modified B-bands with variously upshifted peak temperatures. The extent of the peak temperature upshift varied in parallel with the extent of inhibition of O2 evolution depending on the anion species. A normal EPR S2 multiline signal was induced in Br--substituted membranes, but its amplitude was reduced to less than 10% in F--, NO-3-, CH3COO--, and SO2-4-substituted membranes, In contrast, the g = 4.1 signal from S2 was markedly enhanced in F-- and NO-3-substituted membranes, not much affected in CH3COO-- and SO2-4-substituted membranes, and decreased to 70% in Br--substituted membranes. Based on these data, the effect of various types of S2 modification on the O2-evolving activity was discussed. It was suggested that anions have an important role in regulating the interaction between the Mn atoms, and thereby adjust the redox properties of the S2 state to enable further transitions beyond S2.

Anions↗
PubMed1987

Assignment of the g = 4.1 EPR signal to manganese in the S2 state of the photosynthetic oxygen-evolving complex: an X-ray absorption edge spectroscopy study.

X-ray absorption spectroscopy at the Mn K-edge has been utilized to study the origin of the g = 4.1 EPR signal associated with the Mn-containing photosynthetic O2-evolving complex. Formation of the g = 4.1 signal by illumination of Photosystem II preparations at 140 K is associated with a shift of the Mn edge inflection point to higher energy. This shift is similar to that observed upon formation of the S2 multiline EPR signal by 190 K illumination. The g = 4.1 signal is assigned to the Mn complex in the S2 state.

Darkness↗
PubMed1992

The g = 2 multiline EPR signal of the S2 state of the photosynthetic oxygen-evolving complex originates from a ground spin state.

The amplitude of the g = 2 Mn 'multiline' EPR signal of the S2 state of the photosynthetic oxygen-evolving complex varies inversely with temperature, indicating that this signal arises from a ground spin state. Electron spin echo experiments at temperatures of 4.2 K and 1.4 K show such Curie-law behavior of the g = 2 multiline EPR signal, as do continuous-wave EPR experiments performed at a non-saturating microwave power in the range from 15.0 K to 4.2 K.

Electron Spin Resonance Spectroscopy↗
PubMed1992

Stabilisation of PS-II-mediated electron transport in oxygen-evolving PS II core preparations by the addition of compatible co-solutes.

Addition of high concentrations of compatible co-solutes such as sugars, sugar alcohols and polyols has recently been shown to lead to marked increases in the thermal stability of oxygen-evolution in chloroplasts (Williams et al. (1992) Biochim. Biophys. Acta 1099, 137-144). In this paper, a similar stabilisation is demonstrated for oxygen-evolving PS II core preparations. The presence of such co-solutes appears, however, to have no ability to stabilise PS II reaction-centre preparations against heat-induced changes in their absorption spectrum. Nor do they protect electron transport from artificial electron donors in PS II core preparations lacking the extrinsic 33 kDa polypeptide of the oxygen-evolution system. Measurements performed on core preparations retaining the 33 kDa polypeptide but lacking the 17 kDa and 23 kDa polypeptides indicate that the co-solutes protect PS-II-mediated electron transport by stabilising the binding of the 33 kDa polypeptide to the core complexes. These findings are discussed in terms of an extension of the general principles underlying the Hofmeister effect observed for soluble proteins to the stabilisation of photosynthetic membrane preparations.

Blotting, Western↗
PubMed1986

Effects of trypsin and calcium chloride on signal IIs in oxygen-evolving PS II preparations.

Photosystem II oxygen-evolving preparations exhibited a reversible loss of signal IIs hyperfine structure when treated with 1.0 M CaCl2. A progressive irreversible loss of hyperfine structure was observed upon trypsin treatment of these preparations. These treatments appear to alter the environment of the radical responsible for signal IIs. Gel electrophoresis of trypsin-treated photosystem II preparations indicates that three polypeptides (45, 32-34, and 26 kDa) are altered with the same kinetics as observed for the trypsin-induced loss of signal IIs. Two of these polypeptides (45 and 32-34 kDa) are core components of photosystem II.

Calcium Chloride↗
PubMed1984

pH dependence of the multiline, manganese EPR signal for the 'S2' state in PS II particles. Absence of proton release during the S1----S2 electron transfer step of the oxygen evolving system.

The pH dependence of oxygen evolution rates, 2,6-dichlorophenolindophenol (DCIP) reduction rates and the intensity of the multiline manganese EPR signal associated with the S2K ok state has been studied using oxygen-evolving spinach (PS) II particles. The oxygen evolution and DCIP reduction rates are found to be very sensitive to pH, with the maximal rates occurring at pH 6.5-7.0. Both the rate and yield of the S2 multiline manganese EPR signal intensity, produced by single flash excitation at room temperature or by continuous illumination at 200 K, are found to be independent of pH, indicating that no proton is released from this manganese site during the S1----S2 electron transfer. These results agree with those from other laboratories showing no proton release on this transition, but using techniques monitoring other species.

2,6-Dichloroindophenol↗
PubMed1986

Do the higher oxidation states of the photosynthetic O2-evolving system contain bound H2O?

A modified mass spectrometer was used to determine whether the higher oxidation states of the photosynthetic O2-evolving system contain substrate water that is not freely exchangeable with the external medium. Our data indicated that the higher oxidation states contain no appreciable bound, non-exchangeable H2O. This suggests that H2O oxidation takes place via a rapid, concerted, all-or-none mechanism rather than by a mechanism involving stable, partially oxidized, H2O-derived intermediates. These findings set definite constraints on possible mechanisms of O2 evolution.

Chloroplasts↗
PubMed1989

The 23 KDa polypeptide of the photosynthetic oxygen-evolving complex from mustard seedlings (Sinapis alba L.). Nucleotide sequence of cDNA and evidence for phytochrome control of its mRNA abundance.

The nucleotide sequence of a cDNA from mustard shows 78% homology in deduced amino acid sequence for the mature protein compared to the sequence for the 23 kDa protein of the oxygen-evolving complex from spinach [(1987) FEBS Lett. 216, 234-240]. There is also a high degree of homology between the premature protein sequences concerning the hydrophobic domain and its distance from the suggested processing site. The accumulation of mRNA for the 23 kDa protein in mustard was stimulated by continuous far-red light and reversal experiments by means of red/far-red light pulse treatment show the involvement of phytochrome in controlling the mRNA abundance for the 23 kDa polypeptide in mustard. The accumulation of the mRNA can be inhibited in white light if the seedlings are treated with the herbicide Norflurazon.

Amino Acid Sequence↗
PubMed1989

N-terminal sequencing of photosystem II low-molecular-mass proteins. 5 and 4.1 kDa components of the O2-evolving core complex from higher plants.

High resolution gel electrophoresis in the low-molecular-mass region combined with electroblotting using polyvinylidene difluoride membranes enabled us to sequence the low-molecular-mass proteins of photosystem II membrane fragments from spinach and wheat. The determined N-terminal sequences, all showing considerable homology between the two plants, involved two newly determined sequences for the 4.1 kDa protein and one for the 5 kDa proteins. The sequence of the 4.1 kDa protein did not match any part of the chloroplast DNA sequence from tobacco or liverwort, suggesting that it is encoded by the nuclear genome. In contrast, the sequence of the 5 kDa protein matched ORF38, which is located just downstream of psbE and psbF in the chloroplast DNA and is assumed to be co-transcribed with them. These two components were associated with the O2-evolving core complex. Sequences of other low-molecular-mass proteins confirmed the previous identification as photosystem II components.

Amino Acid Sequence↗
PubMed1989

A 10 kDa polypeptide associated with the oxygen-evolving complex of photosystem II has a putative C-terminal non-cleavable thylakoid transfer domain.

The N-terminal amino acid sequence of the 10 kDa polypeptide associated with the oxygen-evolving complex of wheat photosystem II has been determined and shown to be homologous to the amino acid sequence of the product of the ST-LS1 gene from potato. The N-terminal sequence of the mature protein indicates that the polypeptide is synthesized with a 39 amino acid N-terminal presequence which is similar to chloroplast import sequences but which lacks a hydrophobic domain for transfer of the protein across the thylakoid membrane. The mature polypeptide has a C-terminal hydrophobic region which shows homology to the hydrophobic thylakoid transfer domain of other lumenal proteins and this hydrophobic region of the 10 kDa polypeptide is suggested to facilitate transfer of the protein across the thylakoid membrane.

Amino Acid Sequence↗
PubMed1993

Flash induced XANES spectroscopy for the Ca-depleted Mn-cluster in the photosynthetic O2-evolving enzyme.

Flash-induced changes of the Mn K-edge absorption spectra have been studied in the oxygen-evolving complex depleted of Ca. The Mn K-edge energy for the Ca-depleted S1-state was lower by 1.5 eV than that for the normal S1-state. The K-edge energy upshifted by 1 eV after one flash, indicative of an oxidation of Mn. After two flashes, the K-edge was elevated as well by 0.4 eV, and then reached a steady-state high level after continuous illumination where the K-edge energy was higher by 0.9 eV than that after one flash. The results indicate that the Mn-cluster and/or its direct ligand could be oxidized up to two electrons but further events are blocked.

Calcium↗
PubMed1996

Unassembled subunits of the photosynthetic oxygen-evolving complex present in the thylakoid lumen are long-lived and assembly-competent.

Physiologically healthy pea chloroplasts contain unassembled, soluble subunits of the oxygen-evolving complex in the thylakoid lumen. We report that the lifetimes of two of these subunits, both on and off the membrane, exceed 8 h in vitro. We also demonstrate that each of the subunits present in the thylakoid lumen is competent for assembly into the membrane-bound complex. These data are consistent with the postulate that the soluble lumen-resident subunits play a role in photosystem II homeostasis. We also demonstrate that the reconstitution of the 33 kDa subunit is inhibited by extremely low concentrations of Triton X-100, suggesting that hydrophobic interactions are involved in the binding of this subunit to the photosystem II reaction center.

Cell Fractionation↗
PubMed1992

A myoglobin evolved from indoleamine 2,3-dioxygenase.

Hemoglobins and myoglobins are some of the best studied proteins. They are distributed in animals, plants and bacteria, and the characteristic two intron-three exon structure is widely conserved in animal globin genes (Jhiang et al., 1988). To date, all of the hemoglobins and myoglobins are believed to have a common origin, and so they are considered to be homologous. We have isolated a completely new type of myoglobin from the red muscle of the abalone Sulculus diversicolor aquatilis. The myoglobin consists of an unusual 41 kDa polypeptide chain, contains one heme per chain and forms a homodimer under physiological conditions. The cDNA-derived amino acid sequence of Sulculus myoglobin showed no significant homology with any other globins, but, surprisingly, showed high homology (35% identity) with human indoleamine 2,3-dioxygenase, a tryptophan degrading enzyme containing heme. This clearly indicates that Sulculus myoglobin evolved from a gene for indoleamine dioxygenase, but not from a globin gene. Sulculus myoglobin lacks the enzyme activity of indoleamine dioxygenase. However, in the presence of tryptophan, the autoxidation rate of oxymyoglobin was greatly accelerated, suggesting that a tryptophan binding site remains near or in the heme cavity as a relic of the molecular evolution.

Amino Acid Sequence↗
PubMed1975

Environmental mutagenesis: evolving strategies in the USA.

A recent Environmental Mutagen Society report (the "Committee 17" report) made recommendations regarding the screening of environmental mutagens and the use of the resulting data. It is important in this respect to employ highly sensitive tests which detect heritable genetic damage of all possible molecular types. Mutagens of artificial origin which are being considered for continued production must be characterized with respect to their level and pattern of distribution and their persistence in the environment in order to perform realistic risk evaluations. Risk evaluation itself, particularly the summation of the effects of numerous distinct mutagens, may be assisted by adopting a common measure of mutagenicity such as the REC (rem-equivalent-chemical). Finally, the Committee 17 report laid out highly specific recommendations concerning maximum permissible exposures to environmental mutagens. Federal regulatory agencies and their enabling legislation are in fact evolving toward the effective control of this highly complicated problem.

Environmental Exposure↗