Gliomas in rodent whisker barrel cortex: a new tumor model

OBJECT

Surgical treatment of gliomas is difficult because they are invasive. Invasion of essential cortex often limits or precludes surgical resection. A tumor model was developed in which the rodent whisker barrel cortex was used to examine how gliomas affect cortical function and structure.

METHODS

Both DBT (mouse) and C6 (rat) glioma cell lines were grown in culture and labeled with the fluorescent marker Dil in vitro. Labeled tumor cells were then injected into the whisker barrel cortex of adult mice and rats. Neurological assessments were made daily and magnetic resonance (MR) images were obtained. Animals were killed by perfusion 6 to 14 days after injection, and histological sections were prepared and studied. Tumors were found in all 20 rats and 10 mice that had been injected with the C6 and DBT cell lines, respectively. The animal cells had been labeled with Dil in vitro, and all in vivo tumors proved to be Dil positive. The MR images revealed the tumor locations and serial MR images demonstrated tumor growth. Histological evaluation confirmed the location of the tumor and the disruption of barrel cortex architecture.

CONCLUSIONS

Both DBT and C6 glioma cell lines can be used to generate malignant glial tumors reproducibly in the whisker barrel cortex. Fluorescent labeling and cytochrome oxidase staining permit visualization of tumor growth patterns, which disrupt the barrel cortex by microscopic invasion and by gross tissue deformation. Magnetic resonance imaging demonstrates the anatomical extension of these tumors in live rodents. Using this model for further studies on the effects of malignant glioma growth on functional cerebral cortex should advance our understanding of the neurological issues and management of patients with these tumors.

Sepsis increases intracellular free calcium in brain

Using magnetic resonance methods and a clinically relevant rodent model of sepsis, we have made in vivo measurements of increased intracellular calcium in a pathologic state in the CNS. The intracellular calcium concentration was increased nearly twofold in septic rat brain compared with controls (p < 0.0001). This result, in a fully intact functioning mammalian system, ties together a previous spectrum of indirect evidence from numerous laboratories suggesting an important role for elevated intracellular calcium in sepsis. In addition, levels of the proinflammatory cytokine tumor necrosis factor-a were elevated threefold in septic rat brain (p < 0.02), and electron microscopic examination revealed scattered injury in approximately 0.25% of glial cells. These findings are discussed in light of the current understanding of the pathophysiology of sepsis.

Lectins isolated from Korean mistletoe (Viscum album coloratum) induce apoptosis in tumor cells

Cytotoxic lectins (KML-C) were isolated from an extract of Korean mistletoe [Viscum album C. (coloratum)] by affinity chromatography on a hydrolysed Sepharose 4B column, and the chemical and biological properties of KML-C were examined, partly by comparing them with a lectin (EML-1) from European mistletoe[Viscum album L. (loranthaceae)]. The hemagglutinating activity of KML-C was inhibited by N-acetyl-D-galactosamine and D-galactose at the minimum concentrations of 6.3 and 12.5 microM/ml, respectively. Further biochemical analyses indicated that KML-C consists of four chains (Mr = 27.5, 30, 31 and 32.5 kDa) which, in some of the molecules, are disulfide-linked, and that the chains of KML-C are distributed over a broad range of isoelectric points (pI), 8.0 to 9.0, whereas the range for EML-1 is 6.6-7.0. A difference was also observed between the N-terminal sequences of KML-C and EML-1. The isolated lectins showed strong cytotoxicity against various human and murine tumor cells, and the cytotoxic activity of KML-C was higher than that of EML-1. Tumor cells treated with KML-C exhibited typical patterns of apoptotic cell death, such as apparent morphological changes and DNA fragmentation, and its apoptosis-inducing activity was blocked by addition of Zn2+, an inhibitor of Ca2+/Mg2+ -dependent endonucleases, in a dose-dependent manner. These results suggest that KML-C is a novel lectin related to the cytotoxicity of Korean mistletoe, and that its cytotoxic activity against tumor cells is due to apoptosis mediated by Ca2+/Mg2+ -dependent endonucleases.

A comparative study on Pb2+ accumulation between Saccharomyces cerevisiae and Aureobasidium pullulans by SEM (Scanning Electron Microscopy) and EDX (Energy Dispersive X-Ray) analyses

Scanning electron microscopy and energy dispersive X-ray analyses were carried out in a comparative investigation of Pb(2+) accumulation in Saccharomyces cerevisiae and Aureobasidium pullulans. In S. cerevisiae, the time required to reach an equilibrium state was shortened from 100 h to 1 h as the initial Pb(2+) concentration decreased from 96.5 mg/l to 16.0 mg/l, whereas the time was almost independent of initial Pb(2+) concentration in A. pullulans. Concomitant with the Pb(2+) accumulation, the cell surface of S. cerevisiae became rough and the amounts of potassium, phosphorus and sulfur on the cell surface decreased. However, significant increase of Pb(2+) on the cell surface after Pb(2+) accumulation was not observed due to Pb(2+) penetration into the cell interior. In contrast, the Pb(2+) accumulation had no significant effect on the surface characteristics of A. pullulans and extreme Pb(2+) accumulation was observed on the cell surface because Pb(2+) could not penetrate into the cell interior due to the existence of extracellular polymeric substances.

Microbial production of inulo-oligosaccharides by an endoinulinase from Pseudomonas sp. Expressed in Escherichia coli

In an attempt to utilize the whole cell as a biocatalyst for inulo-oligosaccharide (IOS) production from inulin, the endoinulinase gene (inu1) of Pseudomonas sp. was cloned into the plasmid pBR322 using EcoRI restriction endonuclease and Escherichia coli HB101 as the host strain. The endoinulinase from E. coli HB101/pKMG50 was constitutively expressed, producing a high yield of IOS (78%). In a batchwise reaction, the initial enzyme concentration determined the total oligosaccharide yield, and excess enzyme decreased the total oligosaccharide yield due to the formation of high amounts of free sugars such as glucose and fructose. The recombinant E. coli expressing endoinulinase activity were immobilized on a polystyrene carrier material, resulting in a dramatically enhanced thermal stability of the enzyme. Continuous production of IOS from inulin was also carried out at 50 degrees C using a bioreactor packed with the immobilized cells. Under the optimal operation conditions, continuous production of IOS was achieved with a productivity of 150 g/l.h for 17 d at 50 degrees C without significant loss of initial activity.

Opposing effects of protein kinase A and C on capacitative calcium entry into HL-60 promyelocytes

Treatment of HL-60 cells with thapsigargin, a microsomal Ca2+/ATPase inhibitor, led to depletion of intracellular calcium stores followed by capacitative calcium entry. Stimulation of adenylyl cyclase with forskolin enhanced thapsigargin-induced Ca2+ influx. The forskolin effect was confirmed by enhanced fluorescence quenching induced by Mn2+ entry into fura-2 loaded cells. 1,9-Dideoxy-forskolin, an inactive analog of forskolin, did not affect capacitative calcium entry. On the other hand, phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, inhibited thapsigargin-induced Ca2+ entry. Histamine and prostaglandin E2 (PGE2) elevated intracellular adenosine 3':5'-cyclic monophosphate (cAMP) levels and enhanced the thapsigargin-induced capacitative calcium entry. Incubation with N-[2-(p-bromocynnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), an inhibitor of protein kinase A (PKA), blocked the forskolin effect, and GF109203X, an inhibitor of protein kinase C (PKC), blocked the phorbol 12-myristate 13-acetate effect. The results suggest that protein kinase A regulates capacitative calcium entry positively, but that protein kinase C regulates Ca2+ influx negatively. Furthermore, after differentiation of HL-60 promyelocytes with dimethylsulfoxide to granulocytes, the inhibitory effect of phorbol 12-myristate 13-acetate became more pronounced, whereas the stimulatory effect of prostaglandin E2 did not change. This result suggests that the regulation of capacitative calcium entry by protein kinase C and protein kinase A develops differently during differentiation.

Prophylactic effect of Korean mistletoe (Viscum album coloratum) extract on tumor metastasis is mediated by enhancement of NK cell activity

We here demonstrated the prophylactic effect of an extract (KM-110) from Viscum album coloratum, a Korean mistletoe, on tumor metastasis produced by highly metastatic tumor cells, colon 26-M3.1 carcinoma, B16-BL6 melanoma and L5178Y-ML25 lymphoma cells, using experimental models in mice. Intravenous (i.v.) administration of KM-110 (100 microg/mouse) 2 days before tumor inoculation significantly inhibited lung metastasis of B16-BL6 and colon 26-M3.1 cells, and liver and spleen metastasis of L5178Y-ML25 cells. The prophylactic effect of KM-110 on tumor metastasis was evident with various administration routes, i.e. subcutaneous, oral, intranasal as well as i.v., and was dependent upon the dose of KM-110 administered. Furthermore, mice given KM-110 (100 microg) 2 days before tumor inoculation showed significantly prolonged survival rates compared with the untreated mice. In a time course analysis of NK activity, i.v. administration of KM-110 (100 microg) significantly augmented NK cytotoxicity to Yac-a tumor cells from 1 to 3 days after KM-110 treatment. Furthermore, depletion NK cells by injection of rabbit anti-asialo GM1 serum completely abolished the inhibitory effect of KM-110 on lung metastasis of colon 26-M3.1 cells. These results suggest that KM-110 possesses immunopotentiating activity which enhances the host defense system against tumors, and that its prophylactic effect on tumor metastasis is mediated by NK cell activation.

Expression of a cDNA encoding Phytolacca insularis antiviral protein confers virus resistance on transgenic potato plants

To develop an antiviral agent and virus-resistant plants, a cDNA clone encoding Phytolacca insularis antiviral protein (PIP) was isolated from a cDNA library constructed with poly(A)+ RNA purified from leaves of P. insularis. The PIP cDNA contains an open reading frame encoding 307 amino acids. The deduced amino acid sequence includes a putative signal sequence of 22 amino acids at the N-terminus. The amino acid sequence of PIP shares 84% homology with that of the pokeweed antiviral protein (PAP). In addition, the mature PIP exhibits the conserved putative active site found in other ribosome-inactivating proteins (RIPs). Recombinant PIP (rPIP) synthesized in Escherichia coli inhibits protein synthesis in vitro in rabbit reticulocyte lysate through the N-glycosidase activity in a similar manner with other RIPs. Local lesion assays with purified rPIP revealed that it inhibits infection of various viruses to plants. Transgenic potato plants expressing the PIP cDNA under the control of the cauliflower mosaic virus 35S promoter are resistant to viruses, such as potato virus X, potato virus Y, and potato leafroll virus. These results suggest that the PIP cDNA could be used for the development of an antiviral agent and transgenic plants resistant against a broad spectrum of plant viruses infecting through both mechanical and aphid transmission.

A2A adenosine receptors inhibit ATP-induced Ca2+ influx in PC12 cells by involving protein kinase A

The regulatory role of A2A adenosine receptors in P2 purinoceptor-mediated calcium signaling was investigated in rat pheochromocytoma (PC12) cells. When PC12 cells were treated with 2-p-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS-21680), a specific agonist of the A2A adenosine receptor, the extracellular ATP-evoked rise in cytosolic free Ca2+ concentration ([Ca2+]i) was inhibited by 20%. Both intracellular calcium release and inositol 1,4,5-trisphosphate production evoked by ATP were not affected by CGS-21680 treatment. However, ATP-evoked Ca2+ influx was inhibited following CGS-21680 stimulation. The CGS-21680-mediated inhibition occurred independently of nifedipine-induced inhibition of the [Ca2+]i rise. The CGS-21680-induced inhibition was completely blocked by reactive blue 2. The CGS-21680 effect was mimicked by forskolin and dibutyryl-cyclic AMP and blocked by Rp-adenosine 3',5'-cyclic monophosphothioate, a protein kinase A inhibitor, or by staurosporine, a general kinase inhibitor. The data suggest that in PC12 cells activation of A2A adenosine receptors leads to inhibition of P2 purinoceptor-mediated Ca2+ influx through ATP-gated cation channels and involves protein kinase A.

Quantification of ion transport in perfused rat heart: 133Cs+ as an NMR active K+ analog

Proper ion balance between intra- and extracellular compartments is necessary for normal physiological function. Conversely, alterations in membrane ion transport occur in numerous pathological states. As a noninvasive, nondestructive spectroscopic technique, nuclear magnetic resonance (NMR) offers a powerful approach to the study of ion balance in intact biological systems. Unfortunately, rare NMR active nuclides that are isotopes of the 100% naturally abundant 23Na+ and 39K+ are not available for tracer kinetic studies of Na1 and K+ transport. However, Cs is a biologically active analog of K+, and the 100% naturally abundant NMR active 133Cs+ nuclide can be employed to examine K+ transport (Davis, D. G., E. Murphy, and R. E. London. Biochemistry 27: 3547-3551, 1988). The distinguishing feature of 133Cs+ is that it naturally gives two separate well-resolved NMR resonances for intra- and extra-cellular 133Cs+, permitting study of the time course changes of either of these compartments independent of the other. In this report, the experimental procedures and compartmental modeling formalism are developed that allow quantitative analysis of Cs+ membrane transport in the perfused rat heart. Intracellular 133Cs+ is shown to be 100% visible by solution-state NMR methods and its influx transport to be markedly inhibited by ouabain, a confirmation of findings previously reported by others. Intracellular 133Cs+ spin-lattice and spin-spin relaxation times at 7 T were determined to be 2.1 +/- 0.3 (SD)s (n = 8) and 0.065 +/- 0.007 (SD) s (n = 8), respectively, for T1 and T2. The rate constant for Na(+)-K(+)-ATPase pump dominated intracellular influx was measured to be 0.25 +/- 0.07 (SD) min-1 (n = 27) and that for efflux 0.005 +/- 0.001 (SD) min-1 (n = 14). The rate constant for 133Cs+ equilibration in the extracellular space at supraphysiological perfusate flow rate (20 ml/min) was found to be 4.6 +/- 0.9 (SD) min-1 (n = 20). Thus extracellular diffusion limitations do not dominate the 133Cs+ transport measurements.

Inhibition of ion transport in septic rat heart: 133Cs+ as an NMR active K+ analog

Sepsis, the systemic response to severe infection, and the resulting multiorgan failure it induces are major contributors to intensive care unit morbidity and mortality. A number of abnormalities in ion transport processes and intracellular free Na+ ([Na+]i) and K+ ([K+]i) concentrations have been reported to occur during sepsis/endotoxemia. An effect of sepsis on the NA(+)-K(+)-ATPase may be an important contribution to changes in intracellular ion balance and the resultant pathophysiology of the disorder. The purpose of this study was to examine the effect of sepsis on the Na(+)-K(+)-ATPase in the isolated perfused rat heart using 133Cs+ nuclear magnetic resonance (NMR). Cs+ is a K+ analog, and 133Cs-NMR offers the opportunity to examine Na(+)-K(+)-ATPase activity in the intact organ via tracer kinetics. Sepsis was induced in halothane-anesthetized male Sprague-Dawley rats using the cecal ligation and perforation (CLP) model. Twenty-four to thirty-six hours after surgery, hearts from CLP or sham-operated rats were perfused with Krebs-Henseleit buffer containing 1.25 mM Cs+. The influx rate constant for Cs+ was decreased by 24% in septic rat hearts, i.e., 0.25 +/- 0.08 (SD) min 1 for controls and 0.19 +/- 0.04 (SD) min-1 for septic animals (P = 0.003). There was no difference for Cs+ efflux [0.005 +/- 0.001 (SD) min-1 for controls and 0.005 +/- 0.002 (SD) min-1 for septic animals; P = 0.8]. These results are consistent with an inhibition of the Na(+)-K(+)-ATPase pump during sepsis/endotoxemia. A decrease in the activity of the Na(+)-K(+)-ATPase pump may be responsible for or contribute to the changes in [Na+]i and [K+]i during the disorder.

Human immunodeficiency virus type 1 Vpu modifies viral cytopathic effect through augmented virus release

We characterized two human immunodeficiency virus type 1 (HIV-1) strains, HIVMCK and HIV213, which have different cytopathic effects in infected cells. HIV213 was highly cytopathic, whereas HIVMCK was not. Biological analyses of chimeric viruses from the cloned infectious DNAs of HIVMCK and HIV213 showed that the Vpu region was responsible for the differing cytopathicity of these viruses. Although HIVMCK expressed Vpu protein, HIV213 did not because of a mutation at the start codon for Vpu. The amounts of envelope glycoprotein and virus particles associated with the cell surface were significantly increased on cells infected with Vpu-deficient viruses compared with Vpu-positive viruses. These data suggest that the highly cytopathic effects of HIV213 (Vpu-deficient) are due to an accumulation of envelope glycoprotein at the infected-cell surface, which would be caused by the retention of progeny virions in the absence of Vpu-facilitated virion release.

Histamine inhibits ATP-induced [Ca2+]i rise through the activation of protein kinase A in HL-60 cells

We investigated the cross-talk between the histamine and ATP receptors in HL-60 human promyelocytes. While both histamine and extracellular ATP increase intracellular Ca2+ concentration ([Ca2+]i) we found that histamine treatment causes a decrease in the subsequent ATP-induced Ca2+ release from intracellular stores and Ca2+ influx from extracellular space. In addition, histamine also inhibited the subsequent ATP-induced inositol 1.4,5-trisphosphate (IP3) generation in a manner comparable to the Ca2+ release. However, histamine did not inhibit thapsigargin-induced Ca2+ release and influx, thus indicating that histamine does not directly inhibit the Ca2+ release-activated channel (CRAC). Ca2+ elevation induced by 2'- and 3'-O-(4-benzoylbenzoyl) ATP (BzATP), which does not produce IP3, was also inhibited by treatment with histamine, suggesting the presence of ATP-gated channels that are regulated by histamine. Treatment with dibutyryl cAMP or 8-bromo-cAMP inhibited the subsequent ATP-induced response similar to histamine. Moreover, the incubation of cells with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), a protein kinase A inhibitor abolished histamine's inhibitory effect on the ATP-induced [Ca2+]i rise and IP3 formation. These results suggest that histamine inhibits both ATP-induced IP3 production and ATP-activated channel opening, through protein kinase A activation.

Induction of cytosolic Ca2+ elevation mediated by Mas-7 occurs through membrane pore formation

Mas-7, a mastoparan derivative, induces elevation of intracellular free Ca2+ concentration ([Ca2+]i) along two independent pathways. The minor contribution occurs via phospholipase C activation and is negatively regulated by treatment with phorbol 12-myristate 13-acetate, a protein kinase C activator. The major contribution involves plasma membrane pores allowing not only Ca2+, Mn2+, and Na+ to enter but also the uptake of ethidium bromide (314 Da) and lucifer yellow (457 Da), but not fura-2 (831 Da), Evans blue (961 Da), and fluorescein-conjugate phalloidin (1,175 Da). Mas-7-induced current, as measured in planar lipid bilayers, reveals that Mas-7-induced pores have two slope conductances, 290 and 94 pS, and that the pores are nonselective for cations. The results also indicate that Mas-7 can produce pores by direct interaction with the plasma membrane without the involvement of membrane proteins and cytosolic factors. Besides in human neuroblastoma cells, similar Mas-7 effects were also observed in other cell lines such as HL-60, 1321N1 human astrocytoma, and bovine chromaffin cells. The data suggest that the Mas-7-induced [Ca2+]i elevation is the combined result of Ca2+ release from stores via phosphoinositide turnover and prolonged Ca2+ influx through membrane pores.

Rates of shutdown of HIV-1 into latency: roles of the LTR and tat/rev/vpu gene region

CEM T-cells chronically infected with most HIV-1 isolates gradually cease virus production over a 4-6 week period. This is due to slow shutdown of virus replication in the majority of the cells, leading to latent infections. We identified one HIV-1 isolate (HIV213) which shut down into latency at a rate much slower than most HIV strains, requiring more than 12 weeks for the majority of the cells to become nonproductive. This indicated that genes of the virus influence the rate of shutting down, or alternatively, the length of time chronically infected cells produce virus. The viral gene(s) influencing differential rates of shutdown were mapped using chimeric viruses composed of the HIV213 genome substituted with various restriction fragments from HIV(MCK), which rapidly progresses into latency. We found that the 3' region of the LTR was the major determinant influencing the rate of shutdown, but the tat/rev/vpu region also slightly influenced this phenotype. These data show that at least these two genomic regions can influence the duration of virus production in chronically infected cells and that polymorphisms in these regions result in phenotypically divergent viruses which go into latency at different rates. It is also possible that this viral property may be an important determinant of clinical outcomes.

CUMC-6, a new diploid human cell line derived from a squamous carcinoma of the uterine cervix

A new cell line, CUMC-6, has been derived from an invasive nonkeratinizing squamous cell carcinoma of the uterine cervix in a 31-year-old patient. It has been maintained in long-term culture for 61 months, and passaged over 300 times. Monolayer-cultured cells were polygonal in shape, showing a pavement-like arrangement and a tendency to pile up without contact inhibition. The epithelial nature of the cultured CUMC-6 cells was confirmed by transmission electron microscopy which demonstrated the presence of desmosomes and tonofilaments. The subcutaneous injection of cultured cells into nude mice gave rise to fast-growing tumors. The transplanted tumor showed similar histological features, but poor differentiation compared to the original tumor. Cultured CUMC-6 cells produced human chorionic gonadotropin beta-subunit (beta-HCG) and alpha-fetoprotein (AFP). Cytosol estrogen and progesterone receptors were not measured in this cell line. The results of isozyme analyses were distinct from the HeLa cell line. Repeated chromosome analysis from passage 6 to 300 revealed that most metaphases of this cell line contained diploid number of chromosomes. The structural abnormality consistently observed in this cell line was the elongation of short arm of chromosome 1. The G- or R-banded pattern of this chromosome suggested inv dup (1) (1pter-->1p34[symbol: see text] 1p21-->1p34[symbol: see text] 1p34-->1qter). Human leukocyte antigen (HLA) typing of CUMC-6 cells indicated the presence of DR12 and DQw3. Analysis of the DNA extracted from the CUMC-6 cells showed the presence of human papillomavirus (HPV) type 16 and 18 DNAs. The results of oncogene analyses using Southern blotting technique revealed amplification and rearrangement of oncogene c-myc and no amplification of oncogene L-myc. Using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique, we have screened CUMC-6 cells for p53 mutation in exons 4 to 9. No mobility shift was observed in this cell line. These results suggest that chromosome 1 abnormality, oncogene alteration, and HPV infection work together in cervical tumorigenesis.

Determination of intracellular calcium in vivo via fluorine-19 nuclear magnetic resonance spectroscopy

Fluorine-19-nuclear magnetic resonance (19F-NMR) spectroscopic detection of the NMR-active Ca2+ indicator 5-fluoro-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (5F-BAPTA) is one method for measuring cytosolic free Ca2+ concentration ([Ca2+]i) and has been used previously to measure [Ca2+]i in isolated cells and perfused organs. The aim of the present investigation was to demonstrate the feasibility of determining [Ca2+]i in vivo and in situ using 19F-NMR and 5F-BAPTA. Experiments were performed on male Sprague-Dawley rats with a surface-coil antenna employed for NMR interrogation. The Ca2+ indicator, 5F-BAPTA, was infused either intravenously (kidney, spleen) or intraventricularly (brain) as a 100 mg/ml solution of the cell-permeant acetoxymethyl ester (5F-BAPTA-AM) in dimethyl sulfoxide. Rats tolerated intravenous infusion without evident change in mean arterial blood pressure. In all tissues examined, kidney, spleen, and brain, [Ca2+]i was approximately 200 nM. To our knowledge, these results represent the first in vivo and in situ determinations of [Ca2+]i employing 19F-NMR.

Effect of sepsis on brain energy metabolism in normoxic and hypoxic rats

Neurological abnormalities including agitation, confusion, disorientation, lethargy, and obtundation are early characteristic findings in patients with sepsis. The etiology of the changes in mental status that occur during severe infection is unknown. We investigated the effects of sepsis on intermediary metabolism and bioenergetics in the brain during normoxia and moderate hypoxia (8% inspired O2 concentration) in rats 36-42 hr following cecal ligation and perforation. The rats were anesthetized with halothane, and brains frozen using the funnel-freezing technique. Perchloric acid extracts of brains were analyzed with fluorometric enzymatic methods and 31P nuclear magnetic resonance spectroscopy. There was no impairment in bioenergetics or intermediary metabolism in septic brain, and sepsis did not compromise the ability of the brain to maintain high-energy phosphates during hypoxia. Hypoxia did cause the brain lactate-to-pyruvate ratio to increase equivalently in both septic and control rats from approximately 9:1 to 20:1 (P < 0.001). We conclude that the neurologic changes which are characteristic of sepsis are unlikely to be due to alterations in cellular energy stores or intermediately metabolism. In addition, there is no evidence that sepsis results in brain cellular hypoxia.

Increased intracellular Ca2+: a critical link in the pathophysiology of sepsis?

Severe bloodstream-borne infection--i.e., sepsis--and the resulting multiorgan failure are now the most common cause of death in many intensive care units. One of the most fundamentally important and controversial issues concerning the pathophysiology of sepsis is the role of intracellular free calcium concentration ([Ca2+]i) in this disorder. Because of the critical role of calcium as an intracellular second messenger and as a potential cellular toxin, resolution of this issue is crucial. Using 19F NMR spectroscopy and the calcium indicator 5,5'-difluoro-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetate we demonstrate in the intact perfused organ, the rat thoracic aorta, that [Ca2+]i in aortic smooth muscle is increased > 2-fold during sepsis. Furthermore, we determined that sodium dantrolene, a drug that decreases release of calcium from the sarcoplasmic reticulum and that is lifesaving in malignant hyperthermia (a disorder due to increased [Ca2+]i), is able to reduce the elevated [Ca2+]i in sepsis to control values when added in vitro or when given in vivo to the animal. These results suggest that an increase in [Ca2+]i is an early event in sepsis and that increased [Ca2+]i may be responsible for, or contribute to, cellular injury. Dantrolene may offer a therapeutic strategy in the treatment of sepsis.

Selective effect of chronic lead ingestion. III: Effect on dopamine beta-hydroxylase activity in brain regions of rats

Selectivity of lead effect on dopamine beta-hydroxylase activity in regions of brai nfrom rats postnatally exposed to lead was tested. Three groups of animals were prepared; (1) Rats exposed to lead at a low dose (0.05% PbAcetate: PbAc); (2) Rats exposed to lead at a high dose (0.2% PbAc); (3) Age-matched normal control rats. At 2, 4, 6 and 8 weeks of age weight of whole brain and body in each group were measured. At the same ages activities of dopamine beta-hydroxylase and Na+K(+)-ATPase were measured in 5 brain regions of each animal. Exposure of rats to lead generally decreased Na+/K(+)-ATPase activity and showed alternative changes of dopamine beta-hydroxylase activity were detected without concomitant changes of Na+/K(+)-ATPase activity were telencephalon and pons/medulla at 2 weeks of age and telencephalon, diencephalon and pons/medulla at 4 weeks of age and midbrain and pons/medulla at 6 weeks of age and cerebellum at 8 weeks of age in rats exposed to lead at a low dose, and those in rats exposed to lead at a high dose were midbrain at 6 weeks of age and cerebellum at 8 weeks of age. These data imply that noradrenergic nervous system in the brain regions described above could selectively be affected by lead.

Concurrent quantification of tissue metabolism and blood flow via 2H/31P NMR in vivo. II. Validation of the deuterium NMR washout method for measuring organ perfusion

The deuterium washout technique of measuring tissue blood flow is based upon NMR detection of HOD (administered as D2O saline, but typically detected as HOD because of rapid proton-deuteron exchange) as a freely diffusible tracer. Though this method is coming into more general use, it has not yet been rigorously validated in vivo against an accepted, independent measure of tissue blood flow. To this end, simultaneous radiolabeled microsphere and HOD washout blood flow measurements were made in rat gastrocnemius muscle. D2O saline was administered either intramuscularly or intraarterially (near the aortic bifurcation), and the sciatic nerve was electrically stimulated to increase the muscle blood flow rate. Over a range of flows of 2 to 80 ml/(100 g.min), comparison of microsphere and HOD washout measurements showed good agreement, with r = 0.92 (n = 16) for intramuscular administration and r = 0.91 (n = 12) for intraarterial administration. These data strongly suggest that the HOD washout technique provides accurate blood flow measurements in skeletal muscle.

Concurrent quantification of tissue metabolism and blood flow via 2H/31P NMR in vivo. III. Alterations of muscle blood flow and metabolism during sepsis

In the conclusion of this series of reports, the application of 31P/2H NMR to investigate the pathophysiology of sepsis in rat hindlimb muscle is demonstrated. Sepsis decreased muscle [PCr] by 18%, 18 +/- 4 SD vs 22 +/- 4 SD mmol/kg tissue wet wt (P = 0.01) in control rats but [ATP] was unchanged, 6 mmol/kg tissue wet wt (P = 0.2). The derived free cytosolic [ADP] in the two groups was similar, [ADP]septic = 0.023 +/- 0.004 SD and [ADP]control = 0.021 +/- 0.003 SD mmol/kg tissue wet wt, and not statistically different (P = 0.14). Likewise [Pi] in the septic and control groups was not statistically different, [Pi]septic = 1.1 +/- 0.5 SD and [Pi]control = 1.2 +/- 0.4 SD mmol/kg tissue wet wt (P = 0.2). Septic rats presented the symptom of respiratory alkalosis evidenced by elevated blood pH. Sepsis decreased muscle blood flow by 33%, P = 0.003, but examination of individual subjects did not demonstrate a correlation with the reduction in [PCr]. Thus, a metabolic energy deficit caused by cellular ischemia/hypoxia is not a likely cause of cellular abnormality in rat hindlimb muscle during sepsis.

Concurrent quantification of tissue metabolism and blood flow via 2H/31P NMR in vivo. I. Assessment of absolute metabolite quantification

In a series of three papers, we demonstrate and validate an approach for concurrent absolute quantification in situ of blood flow and energy metabolism with a modification of the NMR method for absolute concentration determination put forth by Thulborn and Ackerman [J. Magn. Reson. 55, 357 (1983)] and later expanded upon by Tofts and Wray. In this first paper of the series, we briefly review the theoretical basis for the concentration measurement and present, for the first time, a successful paired validation of metabolite quantification via 31P surface-coil NMR through corroborative in vitro enzymatic assays. The paired radiolabeled microsphere validation of blood flow measurement via 2H surface-coil NMR employing D2O as a freely diffusible tracer and the concurrent determination of blood flow and energy metabolism in a septic rat model are presented in the accompanying second and third paper to complete the series. In this article a classical RF tank circuit is employed to describe the effect of conductive sample loading on the NMR receiver by considering its apparent series resistance. It is shown in an easily visualized generalizable manner that the effect of sample loading on the observed NMR signal intensity can be accounted for quantitatively by monitoring changes in 90 degrees pulse width at constant power at a fixed reference point, i.e., Ssample = Sphantom (PW90phantom/PW90sample). In a series of paired experiments the absolute concentrations of high energy phosphates obtained from resting rat leg muscle (n = 4) in situ (NMR) and in vitro (enzymatic) were determined as follows: [PCr]NMR = 17.2 +/- 0.8 SD, [PCr]enzymatic = 17.3 +/- 2 SD, [ATP]NMR = 5.1 +/- 0.8 SD, [ATP]enzymatic = 5.0 +/- 0.2 SD mmol/kg tissue wet wt. Results of these two independent methods of concentration determination were not statistically different (P = 0.94 and P = 0.74 respectively) and serve to rigorously validate the Thulborn approach for absolute quantification of phosphorous metabolites in situ via NMR. Furthermore, these results strongly suggest that ATP and PCr in resting rat leg muscle under normal physiologic conditions are 100% NMR visible. The free cytosolic [ADP]NMR was estimated from the creatine kinase reaction equilibrium expression to be 0.022 +/- 0.003 SD mmol/kg tissue wet wt.

Evaluation of the role of cellular hypoxia in sepsis by the hypoxic marker [18F]fluoromisonidazole

Underlying cellular hypoxia, which may be difficult to detect, has been postulated to be a major cause of morbidity and mortality in sepsis. We employed the novel hypoxic marker [18F]fluoromisonidazole to determine whether cellular hypoxia was present in a peritonitis model of sepsis in the rat. A second group of septic and control rats had organ blood flow measurements determined by the radiolabeled microsphere technique to relate possible ischemia to decreased organ perfusion. No evidence of cellular hypoxia was detected in skeletal muscle, brain, liver, heart, or diaphragm in the septic rats. Ligation of the femoral artery caused a greater reduction in flow (55% decrease vs. 20% decrease, P less than 0.05) and an increased retention of [18F]fluoromisonidazole in skeletal muscle of the septic rats. We conclude that sepsis does not invariably result in systemic, i.e., multiorgan, cellular hypoxia and that underlying cellular hypoxia is not the major pathophysiological abnormality in sepsis. The greater reduction in muscle blood flow and the increased retention of [18F]fluoromisonidazole in the ischemic muscle of septic rats implies that they may be more vulnerable to hypoxia.

Effect of pretreatment on simultaneous saccharification and fermentation of hardwood into acetone/butanol

The effectiveness of pretreatments on hardwood substrate was investigated in connection with its subsequent conversion by simultaneous saccharification and fermentation (SSF), using Clostridium acetobutylicum. The main objectives of the pretreatment were to achieve efficient separation of lignin from carbohydrates, and to obtain maximum sugar yield on enzymatic hydrolysis of pretreated wood. Two methods have given promising results: (1) supercritical CO2-SO2 treatment, and (2) monoethanolamine (MEA) treatment. The MEA pretreatment removed above 90% of hardwood lignin while retaining 83% of carbohydrates. With CO2-SO2 pretreatment, the degree of lignin separation was lower. Under the scheme of SSF, the pretreated hardwood was converted to acetone, butanol, and ethanol (ABE) via single stage processing by cellulase enzyme system and C. acetobutylicum cells. The product yield in the process was such that 15 g of ABE/100 g of dry aspen wood was produced. In the overall process of SSF, the enzymatic hydrolysis was found to be the rate-limiting step. The ability of C. acetobutylicum to metabolize various 6-carbon and 5-carbon sugars resulted in efficient utilization of all available sugars from hardwood.