Methylation of selenium in the aquatic environment

Conversion of inorganic and organic selenium compounds to volatile selenium compounds (dimethyl selenide, dimethyl disetenide, and an unknown compound) by microorganisms in lake sediment has been observed. This conversion could also be effected by pure cultures of bacteria and fungi. Such transformations are significant in the transportation and cycling of elements in the environment.

Variation in Quantitative Requirements for Na for Transport of Metabolizable Compounds by the Marine Bacteria Alteromonas haloplanktis 214 and Vibrio fischeri

The rates of uptake by Alteromonas haloplanktis of 19 metabolizable compounds and by V. fischeri of 16 of 17 metabolizable compounds were negligible in the absence of added alkali-metal cations but rapid in the presence of Na. Only d-glucose uptake by V. fischeri occurred at a reasonable rate in the absence of alkali-metal cations, although the rate was further increased by added Na, K, or Li. Quantitative requirements for Na for the uptake of 11 metabolites by A. haloplanktis and of 6 metabolites by V. fischeri and the characteristics of the Na response at constant osmotic pressure varied with each metabolite and were different from the Na effects on the energy sources used. Li stimulated transport of some metabolites in the presence of suboptimal Na concentrations and for a few replaced Na for transport but functioned less effectively. K had a small capacity to stimulate lysine transport. The rate of transport of most of the compounds increased to a maximum at 50 to 300 mM Na, depending on the metabolite, and then decreased as the Na concentration was further increased. For a few metabolites, the rate of transport continued to increase in a biphasic manner as the Na concentration was increased to 500 mM. Concentrations of choline chloride equimolar to inhibitory concentrations of NaCl were either not inhibitory or appreciably less inhibitory than those of NaCl. All metabolites examined accumulated inside the cells against a gradient of unchanged metabolite in the presence of Na, even though some were very rapidly metabolized. The transport of l-alanine, succinate, and d-galactose into A. haloplanktis and of l-alanine and succinate into V. fischeri was inhibited essentially completely by the uncoupler 3,5,3',4'-tetrachlorosalicylanilide. Glucose uptake by V. fischeri was inhibited partially by 3,5,3',4'-tetrachlorosalicylanilide and also by arsenate and iodoacetate.

Pressure locking of the subgel phase of hydrated dipalmitoyl phosphatidylcholine bilayers: a Raman spectroscopic study

Raman spectra of aqueous dispersions of 1,2-dipalmitoyl-phosphatidylcholine (DPPC) have been measured as a function of pressure (up to 46 kbar) for samples incubated at 2 degrees C and for nonincubated DPPC samples subjected to equally high pressure. The nature of the transition from the GII gel phase of the hydrated lipid into the subgel phase on incubation is entirely different from that of the transition from the GII gel phase into the GIII gel phase of the nonincubated lipid. The GIII gel phase has a monoclinic interchain packing, while the subgel phase exhibits a triclinic interchain structure. It is shown that pressure cannot induce the transition from the GII gel phase to the subgel phase; however, it does stabilize the subgel phase above the subtransition temperature. The mechanism for the formation of the subgel phase and the complex phase behavior of the gel phase of DPPC are rationalized in terms of the dynamic properties of the acyl chains of the lipid molecule.

Chronic high dose captopril decreases total heart rate variability and increases heart rate in C57BL/6J mice

The effects of high dose captopril, within the therapeutic range, on autonomic activity are unknown in those with normal cardiovascular function. Thus the study aims were to assess the effects of high dose captopril on autonomic function in mice. Autonomic activity was measured using heart rate variability (HRV). ECG recordings were obtained from 18 Male C57BL/6J mice (20-25 g) subdivided into control (N=8) or mice receiving oral captopril (0.688 mg/ml captopril in the drinking water for 6 weeks, N=10). HRV results for linear and non-linear parameters were attenuated following chronic captopril for 6 weeks compared to control. Captopril was associated with a trend for an increase in average heart rate and approximate entropy (ApEn), a non-linear measure of HRV decreased significantly compared to control (p<0.05). In conclusion high dose captopril reduces total HRV and increases heart rate in normotensive mice with normal cardiac function.

High pressure fourier transform infrared spectroscopy of poly(dA)poly(dT), poly(dA) and poly(dT)

The effect of hydrostatic pressure upon the DNA duplex, poly(dA)poly(dT), and its component single strands, poly(dA) and poly(dT) has been studied by fourier-transform infrared spectroscopy (FT-IR). The spectral data indicate that at 28 degrees C and pressures up to 12 kbar (1200 MPa) all three polymers retain the B conformation. Pressure causes the band at 967 cm(-1), arising from water-deoxyribose interactions, to shift to higher frequencies, a result consistent with increased hydration at elevated pressures. A larger pressure-induced frequency shift in this band is observed in the single stranded polymers than in the double stranded molecule, suggesting that the effect of pressure on the hydration of single strands may be greater than upon a double stranded complex. A pressure-dependent hypochromicity in the bands attributed to base stacking indicates that pressure facilitates the base stacking in the three polymers, in agreement with previous assessments of the importance of stacking in the stabilization of DNA secondary structure at ambient and high pressures.

Uterine effects of tamoxifen: a prospective study

The purpose of the study was to evaluate tamoxifen-associated changes in the vagina and uterus in postmenopausal breast cancer patients. Between June 1994 and December 1998, 45 patients enrolled in a prospective study before commencing tamoxifen therapy. Patients with endometrial thickness >5 mm or neoplasia were excluded. Transvaginal ultrasonography, vaginal maturation indexes (VMI), and endometrial biopsy were performed at baseline and repeated at 6 months (n= 42), 1 year (n= 39), 2 years (n= 32), 3 years (n= 26), 4 years (n= 19), and 5 years (n= 15). For the 39 patients followed for 1 year, VMI (% parabasal/intermediate/superficial) was 21/71/8 at baseline compared with 1/90/9 at 1 year (P value = 0.0008/0.001/0.78). At baseline, mean endometrial thickness and uterine volume were 2.6 mm and 64 cm(3), respectively, compared with 5.8 mm and 84 cm(3) at 1 year (P= 0.0002, 0.002). At baseline, 80% of patients had atrophic endometrium and 9% proliferative endometrium compared with 61% and 26% at 1 year, respectively (P= 0.04). No cases of endometrial hyperplasia or adenocarcinoma were detected. Findings observed at 6 months persisted through 5 years of follow-up. Tamoxifen exerts a weak estrogenic effect on the vagina and uterus in highly prescreened postmenopausal women without preexisting endometrial pathology.

Positive and negative modulation by AMPA- and kainate-receptors of striatal kainate injection-induced neuronal loss in rat forebrain

We investigated the roles of ionotropic glutamate receptor subtypes in mediating striatal kainate injection-induced neuronal loss in rat forebrain, using subtype-specific antagonists and histochemical staining. Our study demonstrates that kainate injected unilaterally into the striatum induces a massive neuronal loss in the rat ipsilateral forebrain through activation of kainate receptors and, to a limited extent, a consequent involvement of M-methyl-D-aspartate (NMDA) receptors, whereas activation of alpha-amino-3-hydroxy-5-methylisoxazol-4-propionate (AMPA) receptors shows a neuroprotective effect. These and previous results suggest that three subtypes of ionotropic glutamate receptors play differential roles in mediating excitatory amino acid (EAA)-induced neurodegeneration.

Strain differences in freezing behavior of PVG hooded and Sprague-Dawley rats: differential cortical expression of cholecystokinin2 receptors

PVG hooded, but not Sprague-Dawley (SD), rats showed remarkable freezing behavior on cat exposure. Experiments using cDNA microarray and reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated that cholecystokinin (CCK)2 receptors were expressed to a greater extent in the PVG hooded rats. A CCK2 antagonist, LY225910, inhibited freezing behavior in the PVG hooded rats while a CCK2 agonist, CCK-4, increased freezing behavior in the SD rats. These results strongly suggest that CCK2 receptors mediate the freezing behavior and the differential expression of these receptors underlie the strain difference in such behavior.

Acute antidepressant-like and antianxiety-like effects of tryptophan in mice

The antidepressant-like, antianxiety-like and sedative effects of tryptophan (TRP), in the absence and presence of p-chlorophenylalanine (p-CPA), and melatonin were studied in mice using the forced-swimming test, open-field test and activity cage, respectively. Single-dose TRP caused an antidepressant-like effect dose dependently up to 125 mg/kg. No significant effect was observed, however, when the TRP dose was increased to 250 mg/kg, i.e. a reversal of effect occurred at high dose. With p-CPA pretreatment, the effects observed at 125 and 250 mg/kg TRP were similar to those obtained at 50 and 125 mg/kg without p-CPA pretreatment, respectively. Melatonin also caused an antidepressant-like effect in a similar manner, but appeared to be less potent than TRP. These results strongly indicate that the antidepressant-like effect of TRP was due to its conversion to 5-hydroxytryptamine (5-HT). An antianxiety-like effect was observed for TRP only at 250 mg/kg dose together with p-CPA pretreatment, while no sedative effect was observed at all. In contrast, melatonin did not produce any antianxiety-like effect, but produced sedation at 200 mg/kg dose. It may be concluded that the antianxiety-like effect of TRP is unrelated to 5-HT and melatonin formation, but associated with TRP itself or, perhaps, with other anxiolytic metabolites.

Polymorphic phases of galactocerebrosides: spectroscopic evidence of lamellar crystalline structures

Fourier transform infrared spectroscopy was applied to study the structural and thermal properties of bovine brain galactocerebroside (GalCer) containing amide linked non-hydroxylated or alpha-hydroxy fatty acids (NFA- and HFA-GalCer, respectively). Over the temperature range 0-90 degrees C, both GalCer displayed complex thermal transitions, characteristic of polymorphic phase behavior. Upon heating, aqueous dispersions of NFA- and HFA-GalCer exhibited high order-disorder transition temperatures near 80 and 72 degrees C, respectively. En route to the chain melting transition, the patterns of the amide I band of NFA-GalCer were indicative of two different lamellar crystalline phases, whereas those of HFA-GalCer were suggestive of lamellar gel and crystalline bilayers. Cooling from the liquid-crystalline phase resulted in the formation of another crystalline phase of NFA-GalCer and a gel phase of HFA-GalCer, with a phase transition near 62 and 66 degrees C, respectively. Prolonged incubation of GalCer bilayers at 38 degrees C revealed conversions among lamellar crystalline phases (NFA-GalCer) or between lamellar gel and crystalline bilayer structures (HFA-GalCer). Spectral changes indicated that the temperature and/or time induced formation of the lamellar crystalline structures of NFA- and HFA-GalCer was accompanied by partial dehydration and by rearrangements of the hydrogen bonding network and bilayer packing mode of GalCer.

Crucial role of kainate receptors in mediating striatal kainate injection-induced decrease in acetylcholine M(1) receptor binding in rat forebrain

We investigated the roles of kainate-, alpha-amino-3-hydroxy-5-methylisoxazol-4-propionate (AMPA)- and N-methyl-D-aspartate (NMDA)-receptors in mediating striatal kainate injection-induced decrease in the binding of acetylcholine M(1) receptors in rat forebrain. After unilateral intrastriatal injection of kainate (4 nmol), the bindings of [3H]kainate (10 nM), [3H]MK-801 (4 nM) and [3H]pirenzepine (4 nM) to the rat ipsilateral forebrain membranes declined, reaching the lowest on day 2 to 4 and recovering on day 8. Saturation binding studies, performed on day 2 post-injection, showed that kainate (1, 2, 4 nmol) dose-dependently decreased B(max) and K(d) of the three ligands. (+)-5-Methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801), a selective NMDA receptor channel blocker, antagonised (from a dose of 4 nmol) kainate-induced decreases in the bindings of [3H]kainate (up to approximately 20%), [3H]MK-801 (up to approximately 90%) and [3H]pirenzepine (up to approximately 70%). In contrast, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a selective non-NMDA receptor antagonist, almost completely abolished (from a dose of 12 nmol) kainate-induced decreases in the bindings of all the three ligands (up to approximately 95-98%). Cyclothiazide, a selective potentiator that enhances AMPA receptor-mediated responses, significantly enhanced (from a dose of 4 nmol) kainate-induced decrease in the binding of [3H]kainate but not that of [3H]pirenzepine or [3H]MK-801. In summary, these results indicate that striatal kainate injection-induced decrease in the binding of acetylcholine M(1) receptors in rat forebrain is dependent on activation of kainate receptors and, to a certain extent, a consequent involvement of NMDA receptors. These and previous studies provide some evidence showing that kainate receptors might play a crucial role in regulating excitatory amino acids (EAA)-modulated cholinergic neurotransmission in the central nervous system (CNS).

A Fourier-transform infrared study of the interaction between germ-cell specific sulfogalactosylglycerolipid and dimyristoylglycerophosphocholine

In this study, we investigated structural and dynamic changes of sulfogalactosylglycerolipid (SGG) and dimyristoylglycerophosphocholine (DMPC) in a liposomal system (SGG+DMPC, molar ratio 2:3) by Fourier-transform infrared (FTIR) spectroscopy. Cooling of the preheated SGG liposomes (5-65 degrees C) revealed that the liquid crystalline-to-gel phase transition was centered at 45 degrees C. SGG+DMPC liposomes showed a single phase transition at 28 degrees C. Spectral changes of the ester C&z. dbnd6;O groups of SGG and DMPC in the mixed liposomes indicated a decrease in their interfacial hydrogen bonding intermolecularly and with water. Analysis of SGG's symmetric and antisymmetric CH(2) stretching bands revealed that the insertion of DMPC into SGG bilayers increased the number of gauche conformers in SGG's hydrocarbon chains. Overall, the SGG+DMPC liposomes were homogeneous, with reduced interfacial hydrogen bonding and increased orientational and conformational disorder of SGG's hydrocarbon chains.

Expression of angiotensin II AT2 receptor in the acute phase of stroke in rats

A male Wistar rat model of stroke (middle cerebral artery occlusion; MCAO) was used to study the angiotensin II (Ang II) receptor subtype 2 (AT2) gene expression by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical staining. After permanent occlusion of the middle cerebral artery (MCA), AT2 receptor gene expression was found to increase in the infarct cortex by 2.7-fold (1 day) and 1.7-fold (3 days), respectively. Positive AT2 immunostaining was also observed in the infarct area of the cerebral cortex. Apoptotic markers were detected in the necrotic area of the stroke cerebral cortex 1 day after MCAO. This demonstrated up-regulation of AT2 receptor may be involved in the apoptosis of tissue repair after stroke.

The adenosine receptor agonist, APNEA, increases calcium influx into rat cortical synaptosomes through N-type channels associated with A2a receptors

N6-2-(4-aminophenyl)ethyladenosine (APNEA) is a nonselective adenosine receptor agonist known to have a high affinity for the adenosine A1 and A3 receptors. It was found to be able to dose-dependently increase the sustained (4 min) Ca2+ influx into rat cortical synaptosomes while 2-chloro-N6-(3-iodobenzyl)-adenosine-5-N-methyluronamide (Cl-IB-MECA), a selective A3 agonist has no effect. However, this effect of APNEA was not affected by the presence of 8-cyclopentyl-1,3-dimethylxanthine (CPT), a selective A1 antagonist; but instead completely abolished by 8-(3-chlorostyryl)caffeine (CSC), a selective A2a antagonist, or omega-conotoxin GVIA. These results show that in the rat cortex, presynaptic A2a receptors can mediate neurotransmitter release by increasing Ca2+ influx through the N-type calcium channels. A1 and A3 receptors appear not to be involved.

Different distributions of nitric oxide synthase-containing neurons in the mouse and rat hypothalamus

The distribution of nitric oxide synthase-containing neurons was studied in the rat and mouse hypothalamus by immunohistochemistry and NADPH-diaphorase histochemistry. Immunostaining and NADPH-diaphorase staining of hypothalamic neurons were comparable in all hypothalamic nuclei of either species except in the arcuate nucleus that stained positive for nitric oxide synthase immunoreactivity but negative for NADPH-diaphorase reactivity. The presence of nitric oxide synthase-immunopositive neurons in the arcuate nucleus was confirmed by nitric oxide synthase immunofluorescence viewed under the confocal microscope at 1 microm thickness. Cross-species comparison showed that, in general, the number and intensity of nitric oxide synthase-containing neurons were much higher in the rat than in the mouse hypothalamus. Differences in the distribution of nitric oxide synthase-containing neurons between these two rodents were found in most hypothalamic nuclei. In particular, two dense clusters of nitric oxide synthase-containing neurons were found in the paraventricular and supraoptic nuclei of the rat hypothalamus in contrast to their scarcity in the same nuclei of the mouse hypothalamus.

Regulation of striatal dopamine release through 5-HT1 and 5-HT2 receptors

Dopamine (DA) release in the striatum is regulated by 5-hydroxytryptamine (5-HT, serotonin) through putative heteroreceptors. However, the effect of 5-HT is controversial. The present study investigated the effects of different 5-HT receptor ligands on DA release in the rat striatum by using in vivo microdialysis in conscious and freely moving rats. Perfusion with 5-carboxamidotryptamine, anpirtoline, pindobind-5-HT1A, and isamoltane demonstrated the involvement of 5-HT1A and 5-HT1B receptors in facilitating DA release. In contrast, 5-HT2 receptors mediated inhibition of DA efflux, as shown by experiments with DOI [R-(-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane] and ketanserin. A 5-HT3 agonist (1-(m-chlorophenyl)-biguanide hydrochloride) did not have any effect. None of the agonists used affected DA uptake into striatal synaptosomes. Unilateral 6-hydroxydopamine lesioning of the nigrostriatal DA pathway led to a selective decrease in 5-HT2 receptors. It is concluded that there are 5-HT2 heteroreceptors at the dopaminergic terminals that mediate inhibition of DA release. Further investigation is required to clarify the localization of the 5-HT1 receptors in the striatum.

Effects of mitogen-activated protein kinase kinase inhibitor PD 098059 on antigen challenge of guinea-pig airways in vitro

1. It has been shown that activation of protein tyrosine kinases is the earliest detectable signalling response to FcepsilonRI cross-linking on mast cell. Following tyrosine kinase activation, a family of mitogen-activated protein kinases (MAPKs) was found to be activated as well. The present study examined the role of MAPK signalling cascade in in vitro model of allergic asthma using a specific MAPK kinase inhibitor PD 098059. 2. Guinea-pigs were passively sensitized with IgG antibody raised against ovalbumin (OA). Effects of PD 098059 on OA-induced anaphylactic contraction of isolated bronchi and release of histamine and peptidoleukotrienes from chopped lung preparations were studied. 3. PD 098059 (10-50 microM) produced only minor reduction of maximal OA-induced bronchial contraction. In contrast, the rate of relaxation of OA-induced bronchial contraction was markedly faster in the presence of PD 098059 than the vehicle control in a concentration-dependent manner. 4. These observations corroborate well with the inability of PD 098059 (5-50 microM) to substantially block the OA-induced release of histamine and with marked inhibition of OA-induced release of peptidoleukotrienes from lung fragments in the presence of PD 098059. Exogenous arachidonic acid-induced release of peptidoleukotrienes from lung fragments was not blocked by PD 098059. 5. In immunoblotting study, we found that p42MAPK was constitutively expressed in guinea-pig bronchi. However, treatment with OA, histamine or LTD4 did not cause activation of p42MAPK. These findings together with the lack of inhibitory effects of PD 098059 on bronchial contraction induced by histamine or LTD4 suggest that histamine- and LTD4-induced bronchial contractions are not mediated by p42MAPK activation. 6. Taken together, our findings show that inhibition of MAPK signalling cascade by PD 098059 significantly reduced the OA-triggered release of peptidoleukotrienes leading to rapid relaxation of anaphylactic bronchial contraction. On the other hand, p42MAPK did not play a role in histamine- or LTD4-induced bronchial smooth muscle contraction suggesting that PD 098059 exerts its inhibitory effects on OA-induced bronchial contraction primarily through inhibition of peptidoleukotrienes release from mast cells.

Interaction between sulfogalactosylceramide and dimyristoylphosphatidylcholine increases the orientational fluctuation of their lipid hydrocarbon chains

The objective of this study was to investigate the interaction between sulfogalactosylceramide (SGC) and dimyristoylphosphatidylcholine (DMPC) in a mixed model liposomal system (molar ratio SGC:DMPC, 2:3). Structural and dynamic changes of the liposome components were monitored by Fourier-transform infrared spectroscopy (FTIR). Thermotropic FTIR analysis of the mixed liposomes showed a single gel/liquid crystalline phase transition, centered at approximately 42 degrees C. Spectral changes of the amide and ester C = O bands arising from functional groups at the interfacial region indicated a reduced hydrogen bonding of these groups in the mixed liposomes. Pressure-tuning FTIR of mixed liposomes showed that the methylene chains of SGC and DMPC were more orientationally disordered than those of the individual lipid SGC liposomes or DMPC liposomes. These results suggest that the mixed liposomes (molar ratio SGC:DMPC, 2:3) consisted of a homogeneous mixture of SGC and DMPC molecules in which mutual shielding reduced hydrogen bonding in the interfacial region, with a concurrent increase in the orientational disorder of the hydrocarbon chains of both SGC and DMPC.

Ischemic tolerance and lipid peroxidation in the brain

Using a modified method of focal ischemic preconditioning (FIP) followed by permanent middle cerebral artery occlusion (MCAO), we studied the effects of ischemic tolerance on infarct volume. The FIP was achieved by obstructing the blood flow into the MCA using miniature clamps at two points simultaneously. The first point was proximal to its origin and the second was where it intersects the middle cerebral vein. In rats subjected to three short conditioning periods (3 x 3 min with 7 min reperfusion between occlusions), there were significant reductions in the infarct volume in the cerebral cortex induced by the subsequent MCAO in FIP-treated rats compared with sham-operated controls. This rapid FIP-induced ischemic tolerance to subsequent MCAO occurred within 1 day and lasted for 5 days. Tissue lipid peroxidation in the cortex was significantly reduced for up to 2 days after FIP. In contrast, lipid peroxidation increased rapidly after MCAO. A significant reduction in this increase was observed in FIP-treated rats, suggesting a correlation with the subsequent reduction in the infarct volume.

Nitric oxide synthase-, N-methyl-D-aspartate receptor-, glutamate- and aspartate-immunoreactive neurons in the mouse arcuate nucleus: effects of neonatal treatment with monosodium glutamate

Glutamate-, aspartate-, N-methyl-D-aspartate receptor (NMDAR1 and 2 subunits)-, and nitric oxide synthase (NOS)-immunoreactive neurons were studied in the arcuate nucleus (AN) of mice treated neonatally with monosodium glutamate (MSG) which is known to cause extensive neuronal loss in this hypothalamic nucleus. It was found that intensely stained glutamate- and aspartate-immunoreactive neurons present in the AN of control mice were completely absent in the MSG-lesioned AN as well as the ventromedial nucleus lateral to the AN. Similarly, NMDAR1-immunoreactive neurons were mostly absent in the MSG-lesioned AN but remained intact in the ventromedial nucleus. There was also a substantial loss of NMDAR2 immunoreactivity within the AN. In contrast, NOS-immunoreactive neurons in the AN survived the neonatal glutamate treatment, although they appeared to be less intensely stained.

Effects of tyrosine kinase inhibitors on antigen challenge of guinea pig lung in vitro

The present study was conducted to examine the effects of two protein tyrosine kinase inhibitors, genistein and tyrphostin 47, on an in vitro model of allergic asthma. Guinea pigs were sensitized with purified IgG raised against ovalbumin (OA). Isolated sensitized bronchial rings contracted in response to OA in a concentration-dependent manner, maximum contraction being achieved at 1 microg/ml. Genistein and tyrphostin 47 concentration-dependently (10-100 microM) inhibited OA-induced anaphylactic contraction of the bronchi, as well as release of histamine and peptidoleukotrienes from chopped lung preparations. Genistein, but not tyrphostin 47, significantly suppressed bronchial contraction to leukotriene D4 at 50 microM and to histamine at 100 microM. Daidzein, an inactive congener of genistein, did not alter OA-induced anaphylactic contraction. However, it slightly reduced bronchial contraction to leukotriene D4 and the OA-stimulated release of peptidoleukotrienes. The inhibitory effects were significantly weaker than those of genistein. Taken together, our results show that tyrphostin 47 inhibited anaphylactic contraction mainly by preventing mast cell degranulation, whereas genistein exerted inhibitory effects partly by blocking mast cell degranulation and partly by attenuating leukotriene D4-induced bronchial contraction. These findings suggest that protein tyrosine kinase inhibitors have a therapeutic potential as mast cell stabilizers in the treatment of allergic diseases such as bronchial asthma.

Comparison of Fourier-transform infrared spectroscopic screening of exfoliated cervical cells with standard Papanicolaou screening

To compare Fourier-transform infrared (FTIR) spectroscopy in screening cervical cytology and standard Papanicolaou (Pap) screening with colposcopic directed biopsy as a "gold standard," we prospectively gathered FTIR samples and Pap smears of all patients attending our program's colposcopy clinics, from February to October 1995. We recorded demographic data for each patient including colposcopy, cytology, treatment follow-up, and histology. Using the colposcopically directed biopsy as the gold standard, exfoliated cervical cells from 301 patients were collected to compare cytology and FTIR spectroscopy. Based on previously established criteria, we provided distinctive definitions of both negative/positive FTIR, cytology, and histology. Results of 301 cases showed 196 positive and 105 negative cytologies. The sensitivity, specificity, false-negative rate, and false-positive rate for the Pap test were 86.6, 90.5, 13.4, and 9.5%, respectively. However, FTIR results versus histology showed 215 positive and 86 negative with a sensitivity of 98.6% and specificity of 98.8%. False-negative and false-positive rates were 1.4 and 1.2%, respectively. In the 12 cervical cancers there were no false-negative FTIR results but 3 false-negative Pap smears. The positive and negative predictive values for FTIR were 99.5 and 96.5% while the Pap values were 95.9 and 72.3%. Compared to standard Pap smears, FTIR has a better false-negative rate and negative predictive value in this preliminary study. Further work, to establish the range of each of the spectral criteria for different grades of dysplasia and that among various infectious effects, needs to be conducted before applying this research tool to a population-based study.

Deficits in water escape performance and alterations in hippocampal cholinergic mechanisms associated with neonatal monosodium glutamate treatment in mice

Mice treated neonatally with monosodium glutamate (MSG) were found to have learning and memory deficits in performing a non-spatial water escape task. Scopolamine impaired the water-escape performance of the control mice but not that of the MSG-treated mice. It was suggested that the water-escape performance deficit in the MSG-treated mice was a result of impaired central cholinergic mechanisms. As such, scopolamine was unable to further incapacitate an already impaired cholinergic system. This is strongly supported by the decreased affinity of the sodium-dependent high-affinity choline uptake observed in the hippocampus. D-Cycloserine, a partial agonist at the glycine site of the NMDA receptor, did not affect the water-escape performance of the MSG-treated and control mice; nor did it alter the effects of scopolamine. This lack of effect of D-Cycloserine may imply that the NMDA receptors are not involved in non-spatial learning, in contrast to their reported involvement in spatial learning.

Increased iron in the substantia nigra of 6-OHDA induced parkinsonian rats: a nuclear microscopy study

The trace elemental concentrations, including iron, in the substantia nigra (SN) of a 6-OHDA induced rat model of Parkinson's disease were measured using nuclear microscopy. Only rats that exhibited amphetamine induced rotation of more than 7 turns/min were used. The results showed that the iron levels were significantly increased in the 6-OHDA lesioned SN, compared with the intact contralateral SN, and the SN of normal control rats injected with ascorbic acid, which showed no significant difference in iron levels between injected and non-injected sides. In both 6-OHDA lesioned and ascorbic acid injected SN, there were no alterations in the levels of calcium, magnesium, copper and zinc. In the 6-OHDA lesioned SN there was an almost complete loss of tyrosine hydroxylase positive cells in the SN. These results suggested that the 6-OHDA induced dopaminergic cell death may be related to the increased iron.

Detecting structural changes at the molecular level with Fourier transform infrared spectroscopy. A potential tool for prescreening preinvasive lesions of the cervix

OBJECTIVE

To study cervical exfoliated cells with Fourier transform infrared spectroscopy (FTIR).

STUDY DESIGN

Consecutive samples from 133 women attending the Dysplasia Clinic, Ottawa Civic Hospital, were collected in balanced electrolyte solution. After centrifugation, two smears were prepared for routine screening. The remainder of the pellet was frozen for FTIR spectroscopic study.

RESULTS

In 120 samples, adequate material was available for spectroscopic study. All smears from 17 women with normal spectra were within normal limits (WNL). One hundred three spectra were abnormal. The corresponding smears were interpreted as: 41 low grade squamous intraepithelial lesions, 20 high grade squamous intraepithelial lesions, 6 atypical squamous cells of undetermined significance, 17 cases with benign cellular changes, and 19 WNL. Ten of 17 cases with benign cellular changes had characteristic spectra consistent with inflammatory changes.

CONCLUSION

FTIR spectroscopy is a highly sensitive technique for detecting cervical abnormalities and a potential tool for prescreening preinvasive lesions of the cervix.

Pressure tuning infrared spectroscopic study of cisplatin-induced structural changes in a phosphatidylserine model membrane

The dynamic effect of cis-diamminedichloroplatinum(II) (DPP) and its aquated metabolite (DDP-OH) on a dimyristoylphosphatidylserine (DMPS) model membrane was investigated by pressure tuning vibrational spectroscopy. The native species (DDP-Cl) and the aquated species (DPP-OH) were both observed to bind to the carboxylate group of the serine as evidenced by a frequency shift of 1622-1620 cm-1. However, only DDP-OH was observed to bind to the phosphate group (PO(-)2). The binding of either drug to DMPS resulted in an increased pressure required to halt the reorientational fluctuations of the acyl chains, indicating that the distance between the chains were increased. The two drugs did not partition into the matrix of the hydrophobic section in the model membrane. Collectively, these data suggest that DDP-Cl and DDP-OH are capable of binding to the polar head group of DMPS, resulting in an enlargement of the area of the head and a subsequent increase in the intermolecular distance between the acyl chains.

A novel analgesic toxin (hannalgesin) from the venom of king cobra (Ophiophagus hannah)

The pharmacological effects of a purified neurotoxin from king cobra (Ophiophagus hannah) venom were studied. Using the hot-plate test, it is shown that this neurotoxin increased latency time dose-dependently when administered i.p. Similar analgesic action was observed when it was administered p.o. or i.c.v. The rota-rod performance, which is a good index for neurological deficits including sedation, muscle relaxant and impairment of motor activity and coordination, was not significantly affected in the dose range of 16-32 ng/g that caused analgesia. The toxin did not increase the convulsion threshold in the dose range of 8-64 ng/g in the maximal electroshock seizure tests. These results demonstrated that this neurotoxin produced analgesia in the dose range of 16-32 ng/g (i.p.) without causing any neurological or muscular deficits. It is further shown that such analgesic action was blocked by naloxone and L-NG-nitro-arginine methyl ester, suggesting the possible involvement of the opioid and nitric oxide systems, respectively. In view of the source of this neurotoxin (O. hannah) and its potent analgesic action, it is proposed that this toxin be named hannalgesin.

Compression of the facial nerve caused increased nitric oxide synthase activity in the facial motor nucleus

Nitric oxide synthase activities in the facial motor nucleus were studied in rats after unilateral compression of the facial nerve. Using a radiometric assay which measured the total soluble nitric oxide synthase activities in the facial motor nucleus and the surrounding tissues, it was found that nitric oxide synthase activities were markedly increased during facial paralysis that resulted from compression of the facial nerve. The subsequent decrease in nitric oxide synthase activities between postoperative days 20 and 40 coincided with the recovery of facial functions. In contrast, staining with NADPH-diaphorase histochemistry revealed that the diaphorase activities in the facial motor neurons were markedly increased between days 20-40 when the total activities as measured biochemically were in decline. However, staining of the vascular endothelium was increased on postoperative day 7 when the total activity was high. It is suggested that the increase in total nitric oxide synthase activities immediately after facial nerve compression may be predominantly endothelial. Since the increase in neuronal NADPH-diaphorase reactivity coincided with the recovery of facial functions, increased neuronal nitric oxide synthase may be a contributing factor to the restoration of facial innervation. The results of this study show that biochemical measurements of soluble nitric oxide synthase activities in tissue homogenates and NADPH-diaphorase histochemical staining in tissue sections may represent two distinct populations of nitric oxide synthase.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of the dopaminergic and serotonergic systems in the rat striatum: effects of selective antagonists and uptake inhibitors

The effects of some selective dopamine (DA) and 5-hydroxytryptamine (5-HT) antagonists and uptake inhibitors on the outflow of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in the striatum were studied using microdialysis in conscious rats. Eticlopride (D2 antagonist, 2.5 mg/kg) increased HVA but decreased 5-HIAA, while nomifensine (DA uptake inhibitor, 10 mg/kg) decreased both. Mianserin (5-HT2 antagonist, 2 mg/kg) and citalopram (5-HT uptake inhibitor, 11 mg/kg) also decreased both HVA and 5-HIAA. The selectivity of these drugs and the time course of their effects on HVA and 5-HIAA suggested that the dopaminergic drugs may affect the serotonergic systems primarily via changes in extraneuronal DA and conversely, serotonergic drugs affect the dopaminergic systems via changes in extraneuronal 5-HT. The results obtained are consistent with current evidence that DA and 5-HT release from striatal terminals are regulated by D2 and 5-HT1B autoreceptors, respectively. They also support the idea that, in the rat striatum, presynaptic inhibitory heteroreceptors are a major mechanism that contributes to a reciprocal interaction of the dopaminergic and serotonergic systems.

Effects of ethanol on peripheral benzodiazepine binding sites in the mouse cerebellum and brain stem

[3H]PK 11195 binding to the peripheral benzodiazepine binding site was investigated in the brain and liver of mice treated with ethanol (4 g/kg, p.o.) daily for 5 days. In the brain stem, Bmax was decreased by 78% in the ethanol-treated group with unaltered Kd (2 nM). The ethanol-withdrawn group did not differ from the control group in both parameters. In the cerebellum, Bmax was decreased by 74% but the binding affinity increased 5-fold as the Kd decreased from 10 to 2 nM. The ethanol-withdrawn group did not differ significantly from the ethanol-treated group. No changes were observed in the cerebrum and liver. These results further support the idea that [3H]PK 11195 binding may be a useful marker for ethanol consumption. The observed changes in these binding sites may represent a functional adaptive response to the ethanol insult and/or a role in the mediation of the effects of ethanol.

Interaction of divalent cations with germ cell specific sulfogalactosylglycerolipid and the effects on lipid chain dynamics

Sulfogalactosylglycerolipid (SGG) is a sulfoglycolipid found ubiquitously in the plasma membrane of mammalian male germ cells. Although its exact cellular function(s) is unknown, it is speculated that SGG may play a role in cation transport, which may be important in sperm-egg interaction. Given the significant role of Ca2+ in many fertilization-related events, the purpose of this study was to determine whether Ca2+ interaction with the negatively charged sulfate group of SGG results in changes to the SGG lipid chain molecular dynamics and to compare these lipid dynamics with those resulting from Na+, Mg2+, or Sr2+ interaction with SGG. Pressure-tuning Fourier transform infrared spectroscopy was used in this study. The results obtained showed that all three divalent cations interacted electrostatically with the sulfate moiety of hydrated SGG, although with varying degrees of strength. It was found that the hydrocarbon chains of hydrated SGG-Na+ multilamellar bilayers were interdigitated, thus increasing disorderedness of the terminal CH3 group of the hydrocarbon chains. The presence of each of the three divalent cations abolished this interdigitation state. Presumably, this is through the cross-linking interaction of each divalent cation with the sulfate groups of neighboring lipid molecules. Moreover, divalent cation interaction was found to increase the lipid chain dynamics of SGG, with Mg2+ inducing the greatest chain disorder followed by Ca2+ and then Sr2+. An increase in chain disorder would increase the bilayer fluidity. Such a phenomenon may prove relevant to the changes observed in the sperm plasma membrane during fertilization-related events.

Pressure-induced correlation field splitting of vibrational modes: structural and dynamic properties in lipid bilayers and biomembranes

Correlation field splittings of the vibrational modes of methylene chains in lipid bilayers, isolated lipid molecules in perdeuterated lipid bilayers, crystalline lipid, and interdigitated lipid bilayers have been investigated by pressure-tuning Fourier-transform infrared spectroscopy. The correlation field splittings of these modes are originating from the vibrational coupling interactions between the fully extended methylene chains with different site symmetry along each bilayer leaflet. The interchain-interactions of the methylene chains with the same site symmetry only contribute to frequency shift of the vibrational modes. The magnitude of the correlation field splitting is a measure of the strength of the interchain-interactions, and the relative intensities of the correlation field component bands provide information concerning the relative orientation of the zig-zag planes of the interacting methylene chains. It has been demonstrated in the present work that the correlation field splitting of the CH2 bending and rocking modes commonly observed in the vibrational spectra of lipid bilayers is the result of the intermolecular interchain-interactions among the methylene chains of the neighboring molecules. The intramolecular interchain-interactions between the sn-1 and sn-2 methylene chains within each molecule are weak. The correlation field splitting resulting from the intramolecular interchain-interactions exhibits a much smaller magnitude than that from the intermolecular interchain-interactions and is observed only at very high pressure. Interdigitation of the opposing bilayer leaflets disturbs significantly the intermolecular interchain-interactions and results in dramatic changes in the pressure profiles of the correlation field component bands of both the CH2 bending and rocking modes. The relative intensities of the correlation field component bands of these modes and the magnitude of the splitting are also altered significantly. These results provide further evidence that the correlation field splitting of the CH2 bending and rocking modes in the vibrational spectra of lipid bilayers is due to the intermolecular interchain-interactions. The present work has also demonstrated that the correlation field splitting of the vibrational modes in lipid bilayers is mainly contributed by the intermolecular interchain-interactions among the nearest neighboring molecules and that the long-range correlation interactions beyond the second neighboring molecules are insignificant.

Effects of high hydrostatic pressures on secondary structure of acetylcholinesterase with and without carbachol

Ultra-high hydrostatic pressures (to 13 kbar) were applied to acetylcholinesterase (AChE) in the presence and absence of 1 mM carbachol (a muscarinic agonist) by means of a piston-and-cylinder system designed for use with Fourier transform infrared spectroscopy. At normal atmospheric pressure, carbachol decreased the number of intramolecular hydrogen bonds and the anti-parallel beta-sheet structure. In the absence of carbachol, pressure dramatically increased the number of intermolecular hydrogen bonds but decreased the alpha-helical, beta-sheet, and anti-parallel beta-sheet segments. In the presence of carbachol, pressure had the opposite effects, decreasing the number of intermolecular hydrogen bonds and increasing the alpha-helix: beta-sheet ratio. Thus in the absence of an attached ligand, the enzyme molecule was vulnerable to pressure-induced distortions that would most likely impair its function. These effects were observed in the absence of a lipid component, indicating that pure proteins are vulnerable to pressure-induced changes in configuration that could affect function.

Prejunctional action of the venom from the Indian red scorpion Mesobuthus tamulus on adrenergic transmission in vitro

Venom (RSV) from the Indian red scorpion, Mesobuthus tamulus (Buthus tamulus), can cause increased peripheral sympathetic activity with consequent enhancement of adrenergic responses. We have therefore investigated the effects of RSV on adrenergic transmission in the rat isolated anococcygeus muscle. The effects of phentolamine (5 microM), tetrodotoxin (2 microM), guanethidine (5 microM), desipramine (1 microM) and reserpine pretreatment in vivo (5 mg/kg s.c. x 24 hr and 5 mg/kg i.p. x 3 hr) on the contractile responses of the rat anococcygeus muscle to RSV (1.5 microgram/ml), field stimulation, noradrenaline (NA, 1 microM or 3 microM) and tyramine (15 microM) were compared. The contractile responses to RSV and to field stimulation were completely blocked by phentolamine, tetrodotoxin, guanethidine and reserpine pretreatment, but the responses were potentiated by desipramine. The contractile responses to tyramine were completely blocked by phentolamine, reserpine pretreatment as well as desipramine. The responses to NA were completely blocked by phentolamine, but were potentiated by guanethidine, desipramine and reserpine. Relatively low concentrations (0.1 microgram/ml x 4) of RSV which did not produce any observable increase in tone of the anococcygeus muscle, potentiated the contractile response of the anococcygeus muscle to field stimulation, but not the responses to exogenous NA; 4-aminopyridine (25 microM x 2) also potentiated the muscle responses to field stimulation. HPLC measurements revealed only very low concentrations (0.10 +/- 0.03 mumol/g venom) of NA in RSV. Thus, the adrenergic agonist action of RSV in the rat isolated anococcygeus muscle can be attributed to the involvement of some prejunctional mechanism(s) of action that stimulates the release of neurotransmitter which differs from the indirect action mediated by tyramine.

Cisplatin and radiation in the treatment of tumors of the central nervous system: pharmacological considerations and results of early studies

PURPOSE

To review the human central nervous system pharmacology of cisplatin, factors that affect cisplatin uptake in tumors, and use alone and with radiation for the treatment of primary brain tumors.

METHODS AND MATERIALS

The authors review their own prior published and unpublished experience and data published by other groups on the above issues.

RESULTS

Cisplatin is one of the most active chemotherapy drugs available for the treatment of solid tumors. It is synergistic with several other agents, including radiation. While it attains only low concentrations in the normal central nervous system, concentrations and plasma-tissue transfer constants for human intracerebral tumors are comparable to those in extracerebral tumors. Tumor type appears to be a more important determinant of platinum concentration than is tumor location, and gliomas do achieve lower concentrations than do other intracerebral or extracerebral tumors. Several other factors have also been identified that correlate with concentrations of cisplatin achieved in human tumors. While cisplatin alone and in combination with other drugs does have some degree of efficacy against primary brain tumors, combining it with cranial irradiation has generally not resulted in any substantial improvement in outcome to date, although some individual studies have been somewhat encouraging. New approaches are currently under investigation.

CONCLUSION

Human pharmacology studies provide a rationale for use of cisplatin in the treatment of human brain tumors, and human and in vitro studies suggest some manipulations that might potentially further augment tumor platinum concentrations. While clinical studies suggest that cisplatin combinations may be of some value vs. human primary brain tumors and brain metastases, and while in vitro studies suggest that cisplatin potentiates radiation efficacy, no combination of cisplatin plus radiation yet tested has appeared to be superior to radiation alone.

Molecular structural changes in Mallory body proteins in human and mouse livers: an infrared spectroscopy study

To study the molecular structure of Mallory body (MB) proteins we applied infrared spectroscopy of the isolated MBs from livers obtained from autopsied patients with alcoholic cirrhosis and griseofulvin-fed (GF-fed) mice. Liver frozen sections were extracted with detergent and digested with deoxyribo- and ribonuclease and collagenase. MB-enriched fractions were then separated out using the aqueous two-phase polymer system. Immunohistochemical and electron microscopic examination showed that the MB composition was virtually identical in human and mouse livers. Infrared spectra of both MB samples showed that the MBs had more numerous and stronger intermolecular hydrogen bonding than did the background control fractions as well as the cytoskeletal fraction from control and GF-fed mice. This may explain why the proteins in MBs are aggregated. The relative amount of beta-sheets was increased compared to the alpha-helices in the MBs, indicating that conformational changes in the cytokeratin peptides of the MBs had occurred. This may explain why the antigenic sites observed in MB proteins show changes in affinity for antibodies to cytokeratins as observed by immunohistochemical staining of MBs.

A microdialysis study on striatal dopamine, 5-HT and metabolites in conscious rats after various treatments: evidence for extravesicular release of dopamine

The effects of death and various treatments that affect the status of nigrostriatal neurones on striatal release of dopamine (DA) and 5-hydroxytryptamine (5-HT) and their metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), 3-methoxy-4-hydroxyphenylethylamine (3-MT), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were studied by in vivo microdialysis. In conscious rats, DA and 5-HT levels were very low compared with their metabolites except 3-MT which was rarely detectable. Upon death by pentobarbitone overdose, there was an immediate surge of the DA level reflecting massive release of the neurotransmitter. This increase was accompanied by a significant increase in 3-MT level but not the other two DA metabolites. Post mortem release of 5-HT was also observed but to a much smaller extent than that of DA. The amounts of amines released appeared to be proportional to the amine stores. When L-dihydroxyphenylalanine (DOPA) was administered to reserpinized rats, the extracellular levels of both DOPAC and HVA increased but not that of DA. However, marked release of DA occurred at death in contrast to reserpinized rats not injected with the precursor. It is evident that exogenous L-DOPA is taken up into the dopaminergic nerve endings and is converted to releasable extravesicular DA, and that this releasable DA is released, at least in part, in accordance with neuronal activities.

The black scorpion Heterometrus longimanus: pharmacological and biochemical investigation of the venom

Documentation on the biological activity (including the lethality) of the venom (BSV) from the black scorpion Heterometrus longimanus is lacking. We have investigated the effects of BSV on adrenergic transmission using the rat isolated anococcygeus muscle (Acm), since the venom from several species of scorpions causes peripheral sympathetic nerve stimulation with enhanced adrenergic responses. The catecholamine content in BSV was also measured by HPLC. The effects of phentolamine (5 microM), guanethidine (5 microM), desipramine (1.5 microM), tetrodotoxin (2 microM) and reserpine pretreatment in vivo (5 mg/kg s.c. x 24 hr and 5 mg/kg i.p. x 3 hr) on contractile responses of the rat Acm to field stimulation, crude BSV (2-10 microliters in 6 ml bath), noradrenaline (3 microM), tyramine (10-15 microM), carbachol (2-3 microM) and potassium chloride (50-75 mM) were investigated. BSV mimicked the agonist actions of noradrenaline (NA) by acting directly on postjunctional alpha-adrenoceptors in the anococcygeus muscle. The LD50 of crude BSV injected i.v. into mice was 0.13 ml per kg mouse. Sequential ultrafiltration of the crude BSV revealed the presence of a substance of low mol. wt which mediates the postjunctional alpha-agonist actions of BSV. HPLC measurements confirmed the presence of noradrenaline (NA; mean concentration of 1.8 +/- 0.3 mM) in BSV; the dopamine concentration (mean of 31 +/- 4 microM) was 60-fold lower than that of NA, whereas adrenaline was not detected in all the 15 samples investigated. Thus, the presence of NA in BSV can account for the postjunctional alpha-agonist actions of the venom in the Acm.

Interactions of Laurdan with phosphatidylcholine liposomes: a high pressure FTIR study

The interactions of 6-lauroyl-2-dimethylaminonaphthalene (Laurdan) with L-alpha-dimyristoylphosphatidylcholine (DMPC) have been studied isothermally at 28 degrees C by Fourier-transform infrared spectroscopy (FTIR) at two pH values (6.8 and 3.0) and over the pressure range of 0.001-25 kbar. The results obtained with Laurdan are compared with those previously obtained with 6-propionyl-2-dimethylaminonaphthalene (Prodan) (Chong et al. (1989) Biochemistry 28, 8358-8363). The objective of this study is to delineate the differential interactions of Prodan and Laurdan with lipid membranes. The Laurdan carbonyl and naphthalene vibrational bands as well as the correlation field splitting of the methylene scissoring mode all indicate that in phospholipid model membrane systems, Laurdan behaves differently from Prodan. The data suggest that the chromophore of Laurdan is embedded somewhat deeper in the membrane than that of Prodan. The correlation field splitting pressure suggests that Laurdan causes more perturbation to DMPC vesicles than Prodan. Instead of being relocated to the exterior of the membrane as is the case of Prodan, Laurdan is found to remain in the membrane even when it is partially positively charged at pH 3. Apparently the stabilizing forces come from the strong van der Waals and hydrophobic interactions between the lauroyl chain and its neighboring lipid molecules. Laurdan seems to remain in the membrane at high pressures (up to 25 kbar). Using deuterated DMPC (d-DMPC) and deuterated L-alpha-dipalmitoylphosphatidylcholine (d-DPPC), we have demonstrated that, at 1 atm, there is a void space between the lauroyl chain of Laurdan and the acyl chain of the matrix lipid, regardless of the physical state of the matrix lipid. This void space, probably caused by the bulky naphthalene ring, is eventually diminished by elevated pressures.

Percutaneous endoscopic gastrostomy: the Heidelberg Repatriation Hospital experience

Percutaneous endoscopic gastrostomy (PEG) was performed on 32 patients (mean age 75 years) who were dysphagic but enteral alimentation was possible. Seventeen patients were recovering from a stroke; the interval between the onset of stroke and PEG averaged 44 days. The procedure was successful and well tolerated by 16 of these 17 patients. Ten patients (31%) still had a functioning PEG, a median of 30 weeks after placement. Seven patients whose swallowing recovered had their tubes removed an average of 3 months after their insertion. Fifteen patients (47%) subsequently died from their underlying disease, a mean of 126 days following PEG. There were no deaths directly related to catheter placement. Percutaneous endoscopic gastrostomy is a useful alternative to surgical gastrostomy in elderly patients with long-term oral feeding problems.

Interactions of indomethacin with central GABA systems

Neurochemical studies showed that indomethacin is a noncompetitive inhibitor of the mouse cortical synaptosomal uptake of [3H]GABA with a Ki of 0.7 mM. Indomethacin also displaced [3H]flunitrazepam and [3H]GABA binding to washed cortical membranes in a competitive manner with IC50 values of 0.18 and 0.55 mM, respectively. It binds to the benzodiazepine receptors with the same characteristics as an inverse agonist and to the GABAA receptors as an antagonist. Behavioral studies showed that indomethacin dose-dependently increased the durations of loss of righting reflex induced by either diazepam or pentobarbitone, decreased rota-rod treading times and effectively prevented generalized seizures induced by pentylenetetrazole, bicuculline, methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate or maximal electroshock treatment. It is concluded that these effects of indomethacin are probably a result of GABA uptake inhibition. The present findings may explain some side effects of indomethacin on the central nervous system, such as impairment of psychomotor functions.

Distinct infrared spectroscopic patterns of human basal cell carcinoma of the skin

Infrared spectroscopy combined with high pressure (pressure-tuning infrared spectroscopy) was applied to the study of paired sections of basal cell carcinomas (BCC) and normal skin from ten patients. Atmospheric pressure IR spectra from BCC were dramatically different from those from the corresponding normal skin. Compared to their normal controls, BCCs displayed increased hydrogen bonding of the phosphodiester group of nucleic acids, decreased hydrogen bonding of the C--OH groups of proteins, increased intensity of the band at 972 cm-1, a decreased intensity ratio between the CH3 stretching and CH2 stretching bands, and accumulation of unidentified carbohydrates. Some of these changes are shared by all human epithelial malignancies studied to date, while some others appear as yet unique to basal cell carcinoma. The diagnostic value of infrared spectroscopy in BCC remains to be determined.

Binding of Ca2+ to sulfogalactosylceramide and the sequential effects on the lipid dynamics

Sulfogalactosylceramide (SGC) is a sulfoglycolipid commonly found in epithelial cells and most animal germ cells. Its cellular function in sperm is unknown, although it has been implicated in cation transport in epithelial cells. The purpose of this study was to determine the lipid dynamic effects of Ca2+ binding to SGC. High-pressure Fourier transform infrared spectroscopy was used in this study. Our spectral results showed that Ca2+ bound to the sulfate moiety of SGC. Moreover, Ca2+ binding weakened the hydrogen bonding of the polar head region of SGC and the hydrocarbon chains became more disordered as revealed by an increase in the correlation field splitting pressure of SGC. Consequently, Ca2+ binding to SGC would increase the fluidity of SGC multibilayers. However, the presence of an alpha-hydroxyl group on the SGC fatty acid was found to strengthen the hydrogen bonding of the polar head region and as a consequence reduced the Ca(2+)-enhanced hydrocarbon chain disorder. Experimental approaches, described in this paper, serve as a model for further studies of the effects of Ca2+ binding on the dynamics of membranes containing SGC or other sulfatides.

High pressure FTIR study of interaction of melittin with dimyristoylphosphatidyl glycerol bilayers

Infrared spectra of hydrated dimyristoylphosphatidyl glycerol (DMPG) and of aqueous dispersions of melittin and DMPG at peptide:lipid molar ratios of 1:10 and 1:4 were recorded as a function of pressure from atmospheric to 22 kbar. Spectral features corresponding to vibrations of the amide linkages in melittin and to various functional groups in DMPG (carbonyl, methlylene, phosphate) were monitored in order to investigate the structure and dynamics of melittin:DMPG dispersions. Melittin was found to cause conformational and orientational disordering of the acyl chains in DMPG bilayers. The magnitude of these disorders was higher for higher concentration of melittin in DMPG. The higher concentration of melittin was also found to disrupt the DMPG bilayers through interactions with the lipid head groups. Such disruption may be related to some of the biological properties of melittin.

Pressure-induced conformational changes in an antigen and an antibody and the implications on their use for hyperbaric immunoadsorption

Pressure-induced conformational changes in two proteins, bovine serum albumin (BSA) and immunoglobulin G (IgG), were studied to assess the application of hyperbaric manipulation to the dissociation of antigen-antibody complexes. Antigen-antibody dissociation is important in the product-recovery phase of immunoadsorption, an affinity purification process. Three techniques were used in parallel for this study, including fluorescence, Fourier transform infrared (FTIR) spectroscopy, and the enzyme-linked immunosorbent assay (ELISA). Employing a fluorescent probe, fluorescent intensity measurements were used to detect protein conformational changes. FTIR spectroscopy was used to determine changes in protein secondary structure induced by high pressure, while the ELISA test was used to examine antibody recognition after the proteins had been pressure-treated. The results from this work demonstrate that IgG is resistant to conformational changes induced by pressures below 2 kbar. In contrast, BSA undergoes reversible conformational changes in this pressure range. However, these conformational changes are not reflected in tests measuring antibody recognition. These findings indicate that IgGs have the potential to be used as recycled ligands in immunoadsorption separation processes. Different antigens that are being considered for purification by immunoadsorption and separated by means of high pressure could be screened by the methods disclosed to determine their stability under high pressure conditions.

FTIR spectroscopic kinetic analysis of alkaline phosphatase under hyperbaric manipulation

For the first time, high-pressure infrared spectroscopy has been used in an enzyme kinetics study. This technique allows not only the investigation of kinetics under very high pressure, but it also allows simultaneous determinion of changes in the secondary structure of enzymes at the corresponding pressures. In the present study, a classical enzyme reaction, the conversion of p-nitrophenol phosphate into p-nitrophenol by alkaline phosphatase was selected to demonstrate the potential of infrared spectroscopy as an alternative physical method in the high-pressure study of enzyme kinetics. The rate constants of this enzyme reaction have been determined as a function of pressure in the pressure range 0.001-14 kbar. The first-order rate constants thus obtained increases with increasing pressure up to 8.3 kbar. At this pressure, the reaction rate decreases abruptly due to the denaturation of the enzyme arising from the conformational changes of some alpha-helical segments in the enzyme molecules into beta-sheet structure. The present results suggest that the pressure-enhanced overall hydrogen-bond strength in the amide groups of the enzyme is one of the factors which stimulate the enzyme activity. Moreover, the dissociation of the dimeric enzyme into its subunits does not inhibit the enzyme activity but only attributes to a slight change in activation volume.

Decreased prostaglandin synthesis in postmortem cerebral cortex from patients with Alzheimer's disease

The syntheses of prostaglandin (PG) F2 alpha, E2 and D2, and thromboxane (TX) B2 from [14C]arachidonic acid were studied in frontal cortex of human control and Alzheimer's disease (AD) brains using the microsomal fractions. Under the assay conditions employed, it was found that the major metabolite of [14C]arachidonic acid was PGE2 accounting for 63% of total prostanoid production; PGF2 alpha accounted for 21.5%, TXB2 for 9%, and PGD2 for 6.5%. When AD samples were compared to control samples, microsomal PG synthesis was significantly decreased, with reduced production of PGE2, PGF2 alpha and PGD2. Such decreases in AD brain seem unrelated to age, sex, postmortem delay and, as far as could be determined, antemortem state. In both control and Alzheimer groups, a history of anti-inflammatory therapy seemed to correlate with increased PG synthesis.

Aggregation of chymotrypsinogen: portrait by infrared spectroscopy

Changes in the secondary structure and aggregation of chymotrypsinogen were investigated by infrared difference spectroscopy in conjunction with temperature and pressure tuning IR spectroscopy; both the amide I' band and side chain bands were studied. A prominent component of the amide I' band in the difference spectrum obtained upon cooling a chymotrypsinogen solution, or increasing the hydrostatic pressure, was observed in the region between 1627 and 1622 cm-1. Under denaturing conditions a white gel was formed, which is attributed to irreversible self-association or aggregation. This process was accompanied by the appearance of two new amide I' bands in the infrared spectrum of the protein: a very strong band at 1618 cm-1 and a weak band at 1685 cm-1. These bands are assigned to peptide segments with anti-parallel aligned beta-strands.

An infrared study of 2H-bond variation in myoglobin revealed by high pressure

A high-pressure Fourier-transform infrared technique was used to probe the evolution of 2H bonds inside the helical segments of myoglobin in relation to p2H, Tris concentration in the medium and iron-ligand nature. The analysis was focused on changes in the conformation-sensitive amide-I' band, reflecting the peptide C = O group stretching vibrations coupled to the in-plane N-2H bending and C = N stretching modes. From data obtained under high pressure, the strength of 2H bonds, inside the alpha-helical segments of the protein at atmospheric pressure, is not simply a function of p2H and salt concentration. At low Tris concentration (50 mM), the strength of these 2H bonds increases with p2H, whereas for a higher Tris concentration (100 mM) this strength is lower at p2H 7 than at p2H 6.0 or 8.5. It is also observed that the azidometmyoglobin molecule exhibits tighter intrahelical interactions and lower sensitivity to pressure than aquametmyoglobin. Information is also presented regarding interhelical interactions in relation to the solvent.

The structure of anhydrous and hydrated dimyristoylphosphatidyl glycerol: a pressure tuning infrared spectroscopic study

The addition of water to anhydrous phospholipids has profound effects on the intermolecular interactions and packing order of phospholipid molecules. These changes, as well as alterations induced by hydration in the orientation of the acyl chains, can be qualitatively assessed using high pressure infrared spectroscopy. Application of this technique to dimyristoylphosphatidyl glycerol (DMPG) showed that hydration causes major changes in (i) the orientation of the carboxyl groups in relation to the glycerol backbone; (ii) the degree of orientational disorder of the acyl chains and (iii) the proximity of neighbouring DMPG molecules. In addition, the frequency of the carbonyl group is shown to be strongly affected not only by changes in the hydrogen bond network, but also by subtle environmental perturbations induced by the conformation of nearby structural units.