Hypothalamic-pituitary-adrenal axis activity and tricyclic response in major depression.

Hypothalamic-pituitary-adrenal (HPA) axis activity was studied in 28 endogenously depressed, hospitalized patients. Measures of HPA activity obtained were baseline serum cortisol level, 24-hour urinary free cortisol excretion, and an overnight 2-mg dexamethasone suppression test. The patients then received double-blind and randomized treatment with imipramine hydrochloride, 150 mg daily, or amitriptyline hydrochloride, 150 mg daily, for four weeks. Four-week treatment response of all patients was compared with pretreatment HPA axis variables, and higher cortisol values after dexamethasone administration were found to be significantly correlated with greater improvement. There were no significant differences between imipramine and amitriptyline response, however, when improvement with each drug was compared with the pretreatment HPA variables.

The dexamethasone suppression test: interaction of diagnosis, sex, and age in psychiatric inpatients.

A group of 277 semiconsecutive psychiatric inpatients manifesting a depressive affect underwent an overnight 1 mg dexamethasone suppression test (DST) and a semistructured diagnostic interview according to DSM-III criteria. For major depressive syndromes (major depression with and without psychosis, bipolar depressed) the sensitivity of the DST was 63.9%, specificity 73.0%, and diagnostic confidence 72.3%. Additionally, a significant interaction between age and baseline cortisol values and nonsuppression rates was found in depressed males but not in nondepressed males nor in depressed and nondepressed females. The authors discuss the implications of these findings.

The effect of age on dexamethasone suppression test results in alcoholic patients.

The authors studied the effects of age, liver function, mean corpuscular volume, and major depression on cortisol concentrations following the dexamethasone suppression test in 31 alcoholics. Only age was significantly correlated with cortisol levels, and it appeared to be an independent effect.

Resolution of neuroleptic malignant syndrome with dantrolene sodium: case report.

A case of neuroleptic malignant syndrome (NMS) with an abrupt onset was terminated quickly with i.v. dantrolene sodium. The prompt and satisfactory outcome after early diagnosis indicates that dantrolene should be considered a useful treatment in NMS.

Hypothalamic-pituitary-adrenal axis activity and age in major depression.

The authors assessed hypothalamic-pituitary-adrenal axis activity in 28 endogenously depressed patients. Postdexamethasone serum cortisol values were found to be positively correlated with age but not sex or severity of depression.

ESR and ENDOR study of adenosine single crystals X-irradiated at 10 K.

Single crystals of adenosine were X-irradiated at 10 K and investigated between 10 and 300 K using K-band ESR and ENDOR spectroscopy. Two free radicals were analyzed. Radical I exhibits small hyperfine couplings to the C8-H, C2-H, and a N3-H protons, and was identified as the N3 protonated base anion radical. Radical II exhibits small hyperfine couplings to a C8-H and an exocyclic -N10-H proton. It is suggested that this is therefore the N10 deprotonated base cation radical. Enough data were not available to analyze a third primary radical believed to be located on the ribose moiety. Upon warming Radical I decays at ca. 40 K with no apparent successor. Likewise, no successor was identified for Radical II, which decays at ca. 100 K. At ca. 200 K there is ESR evidence for the C2 and C8 H-addition radicals. Their precursors have not been identified.

Radical formation in X-irradiated single crystals of guanine hydrochloride monohydrate. II. ESR and ENDOR in the range 10-77 K.

In a study of guanine.HCl.H2O (Gm) single crystals X-irradiated at temperatures between 10 and 77 K, three radical species were found and characterized by ESR and ENDOR spectroscopy. All three are primary products in that they were present immediately following irradiation at T less than 10 K. Radical I, which apparently can exist in two slightly different conformations, was identified as the product of electron gain by the parent molecule and subsequent protonation at O6. Radical I decayed only after warming the crystals beyond 250 K. Radical II was the guanine cation previously reported (D. M. Close, E. Sagstuen, and W. H. Nelson, J. Chem. Phys. 82, 4386 (1985)); however, ENDOR data are reported here which confirm the previous results. The guanine cation in Gm resulted from electron loss from the parent and subsequent deprotonation at N7. It is proposed that Radical III results from OH attack at C8 of the parent molecule, followed by rupture of the C8-N9 bond and ring opening. The OH radicals thought to produce Radical III result from electron loss by the cocrystallized water molecules. The reaction leading to Radical III, unusual in solid-state radiation chemistry, is thought to be mediated by the specific hydrogen bonding network in this crystal.

Radical formation in X-irradiated single crystals of guanine hydrochloride monohydrate. III. Secondary radicals and reaction mechanisms.

This work involves an ESR and ENDOR study of the reactions of the three primary radicals observed in X-irradiated single crystals of guanine hydrochloride monohydrate. Radical I, the O6-protonated anion, decays at 250 K yielding a stable room temperature radical (Radical V). The experimental evidence indicates that Radical V results from H-abstraction at N9 of a neighboring molecule. Radical II, the N7-deprotonated cation, decays at 60 K with no detectable successor. Radical IV, a C8 H-addition radical, is formed when an imidazole ring-opened radical (Radical III) decays at 150 K. The added H-atom was found to be from an easily exchangeable source. It is proposed that Radical III decays by the formation of a diamagnetic formamido molecule and an H-atom. It is important to note that Radical IV, the purine H-addition radical, is the result of basic oxidation events. Previous assumptions have been that purine H-addition radicals result either from reduction, i.e., protonation of a pristine anion, or from the "excitation pathway," by addition of H-atoms dissociated from superexcited purine bases.

ESR/ENDOR study of guanosine 5'-monophosphate (free acid) single crystals X-irradiated at 10 K.

Single crystals of the free base of guanosine 5'-monophosphate were X-irradiated at 10 and at 65 K and investigated between these temperatures and room temperature using K-band ESR and ENDOR spectroscopy. Three free radicals were detected in this temperature range. Two of these were identified as the O6-protonated anion radical and the C8 H-addition radical. Both of these species were present immediately after irradiation at 10 K. The anion radical was formed in two slightly different conformations, of which one decayed at about 150 K and the second at about 250 K. No successor radicals could be detected following the decay of the anion radical. The C8 H-adduct was stable at all temperatures used. The use of partially deuterated crystals confirmed the assignments made and showed that the main pathway for the formation of the C8 H-adduct consisted of addition of a proton from an easily exchangeable site. It is suggested that the C8 H-adduct is formed subsequent to a primary oxidation event localized either at the guanine base or at a nearby water of crystallization. Possible mechanisms for the formation of this product are discussed.

Free radical formation in single crystals of 9-methyladenine X-irradiated at 10 K. An electron paramagnetic resonance and electron nuclear double resonance study.

Single crystals of 9-methyladenine were X-irradiated at 10 K and at 65 K and were studied using K-band EPR, ENDOR and field-swept ENDOR (FSE) techniques in the temperature range 10 K to 290 K. Three major radicals are stabilized in 9-methyladenine at 10 K. These are: MA1, the adenine anion, probably protonated at N3; MA2, the species formed by net hydrogen abstraction from the 9-methyl group; and MA3, the radical formed by net hydrogen addition to C8 of the adenine moiety. Radical MA1 decayed at about 80 K, possibly into the C2 H adduct (MA4). The other two species (MA2, MA3) were stable at room temperature. A fifth radical species was clearly present in the EPR spectra at 10 K but was not detectable by ENDOR. This species, which decayed above 200 K (possibly into MA3), remains unidentified. The radical population at room temperature is as described by previous authors. The mechanisms for radical formation in 9-methyladenine are discussed in light of the hydrogen bonding scheme and molecular stacking interactions.

The structure of the guanine cation: ESR/ENDOR of cyclic guanosine monophosphate single crystals after X irradiation at 10 K.

Following X irradiation of 3',5'-cyclic guanosine monophosphate single crystals at 10 K, several free radicals were trapped and detected by ESR/ENDOR/FSE spectroscopy. The two dominant species both have unpaired spin located on the guanine base. One is the product of net hydrogen atom loss from the exocyclic amino group. The spectroscopic characteristics of this resonance leave this assignment unambiguous. The experimental conditions make it likely that this species was formed by deprotonation of the guanine base cation. The nature of the other species is more uncertain. However, the evidence is consistent with the assignment that it is a net OH adduct to the C4 position of the base. Several species in which the unpaired spin was located on the sugar-phosphate region of the molecule were also observed. The mechanisms for the decay of the primary radicals, also leading to the well-known C8 hydrogen addition radical of the guanine base, are described and discussed.

Ionization of adenine derivatives: EPR and ENDOR studies of X-irradiated adenine.HCl.1/2H2O and adenosine.HCl.

Following X irradiation of adenine.HCl.H2O at 10 K, evidence for five distinct radical products was present in the EPR/ENDOR. (In both adenine.HCl.1/2H2O and adenosine.HCl, the adenine base is present in a cationic form as it is protonated at N1). From ENDOR data, radical R1, stable at temperatures up to 250 K, was identified as the product of net hydrogen loss from N1. This product, evidently formed by electron loss followed by proton loss, is equivalent to the radical cation of the neutral adenine base. Radical R2, unstable at temperatures above 60 K, was identified as the product of net hydrogen addition to N3, and evidently formed by electron addition followed by proton addition. Radicals R3-R5 could not be identified with certainty. Similar treatment of adenosine.HCl provided evidence for six identifiable radical products. Radical R6, stable to ca. 150 K, was identified as the result of net hydrogen loss from the amino group, and evidently was the product of electron loss followed by proton loss. Radical R7 was tentatively identified as the product of net hydrogen addition to C4 of the adenine base. Radical R8 was found to be the product of net hydrogen addition to C2 of the adenine base, and R9 was the product of net hydrogen addition to C8. Radical R10 was identified as the product of net hydrogen abstraction from C1' of the ribose, and R11 was an alkoxy radical formed from the ribose. With the exception of R11, all products were also found following irradiation at 65 K. Only radical R8 and R9 were stable at room temperature. Most notable is the different deprotonation behavior of the primary electron-loss products (radical R1 vs. R6) and the different protonation behavior of the primary electron-gain products (radical R2 vs. no similar product in adenosine.HCl). The major structural difference in the two crystals is the electrostatic environment of the adenine base. Therefore, this study provides further evidence that environmental influences are important in determining proton transfer processes.

Free radical formation in single crystals of 2'-deoxyguanosine 5'-monophosphate tetrahydrate disodium salt: an EPR/ENDOR study.

Single crystals of 2'-deoxyguanosine 5'-monophosphate were X-irradiated at 10 K and at 65 K, receiving doses between 4.5 and 200 kGy, and studied using K-band EPR, ENDOR, and field-swept ENDOR (FSE) spectroscopy. Evidence for five base-centered and more than nine sugar-centered radicals was found at 10 K following high radiation doses. The base-centered radicals were the charged anion, the N10-deprotonated cation, the C8 H-addition radical, a C5 H-addition radical, and finally a stable radical so far unidentified but with parameters similar to those expected for the charged cation. The sugar-centered radicals were the H-abstraction radicals centered at C1', C2', C3', and C5', an alkoxy radical centered at O3', a C5'-centered radical in which the C5'-O5' phosphoester bond appears to be ruptured, a radical tentatively assigned to a C4'-centered radical involving a sugar-ring opening, as well as several additional unidentified sugar radicals. Most radicals were formed regardless of radiation doses. All radicals formed following low doses (4.5-9 kGy) were also observed subsequent to high doses (100-200 kGy). The relative amount of some of the radicals was dose dependent, with base radicals dominating at low doses, and a larger relative yield of sugar radicals at high doses. Above 200 K a transformation from a sugar radical into a base radical occurred. Few other radical transformations were observed. In the discussion of primary radicals fromed in DNA, the presence of sugar-centered radicals has been dismissed since they are not apparent in the EPR spectra. The present data illustrate how radicals barely traceable in the EPR spectra may be identified due to strong ENDOR resonances. Also, the observation of a stable radical with parameters similar to those expected for the charge guanine cation is interesting with regard to the nature of the primary radicals stabilized in X-irradiated DNA.

On the proton transfer behavior of the primary oxidation product in irradiated DNA.

Results are surveyed from investigations of six adenine and six guanine crystal systems X-irradiated and studied at temperatures near that of liquid helium (T less than 10 K). Basic conclusions from the overall results are that the primary oxidation products deprotonate rapidly, and that the specific site of deprotonation is environment-dependent. The following systematic behaviors were identified: (1) in no case was there deprotonation at a site hydrogen-bonded to a halide ion (three examples with guanine and two with adenine); (2) likewise, in no case was there deprotonation at a site hydrogen-bonded to a phosphate group (three examples, all with guanine); (3) in no case was there deprotonation at a site involving an greater than N-H . . . N less than hydrogen bond; (4) in all cases except one, the site of net deprotonation involved greater than N-H . . . O hydrogen bonds. In the remaining case, the leaving proton was uninvolved in hydrogen bonding. A review of results obtained previously from DNA leads to the conclusion that the actual protonation states of DNA oxidation products are unknown at the present time. The results presented here predict with high probability that such DNA products also will deprotonate, but the environment dependence makes it difficult to predict the specific sites. Thus the importance of obtaining this information from direct experimental evidence is increased.

Free radical formation in X-irradiated anhydrous crystals of inosine studied by EPR and ENDOR spectroscopy.

Single crystals of anhydrous inosine were studied subsequent to exposure to high and low doses of X radiation at 10 K using K-band, EPR, ENDOR, and field-swept-ENDOR (FSE) techniques. Immediately following high radiation doses at 10 K at least eight different radicals, RI-RVIII, were observed. All radicals, except for RVIII, were also observed at low doses, but the relative yields varied with the radiation doses. RI, which decayed with no observable successor at about 65 K, has magnetic characteristics similar to those expected for the hypoxanthine base cation. RII, the dominating radical at low radiation doses, exhibits only one hyperfine coupling amenable for ENDOR analysis. From the nature of this coupling and the EPR and FSE characteristics of the resonance, it is suggested that RII is formed by addition of a neighbor sugar fragment to the C2 position of a hypoxanthine base, forming a C2-O5'-C5' ester bond. RII is unstable and decayed at about 60 K without any detectable successor. RIII and RIV are the C2 and C8 H-addition radicals, respectively. These species are formed in minor amounts after irradiation at low temperatures, and they are the only observable radicals left at room temperature. Two sugar-centered radicals, RV and RVI, are formed by net H-abstraction from the C4' and C5' positions, respectively. These radicals dominate the EPR spectra after high radiation doses at low temperatures. A transformation from RV into RIII, the C2 H-adduct, started at about 80 K. Similarly, a transformation of RVI into RIV started at about 210 K. Several minor species were analyzed. RVII is characterized by an alpha-coupling due to 26% spin density at C8, and RVIII is characterized by 12% pi-spin density at N1. Possible structures for these radicals are discussed.

Radiation damage to DNA base pairs. I. Electron paramagnetic resonance and electron nuclear double resonance study of single crystals of the complex 1-methylthymine.9-methyladenine X-irradiated at 10K.

Single crystals of the complex 1-methylthymine.9-methyl-adenine were X -irradiated at 10 and at 65 K and studied in the temperature range 10 to 290 K using K-band EPR, ENDOR and field-swept ENDOR (FSE) techniques. The EPR and ENDOR spectra are dominated by two major and four minor resonances. The two major resonances are: MTMA1, the well-known radical formed by net hydrogen abstraction fr om the CS methyl group of the thymine moiety, and MTMA2, the radical formed by net hydrogen abstraction from the N1 methyl group of the thymine moiety. The latter product has not been observed previously in any 1-methylthymine derivative. The four minor resonances are: MTMA3, the anion of 1-methylthymine, possibly protonated at the O4 position; MTMA4, the well-known species formed by net hydrogen addition to C6 of the thymine moiety; MTMA5, the species formed by net hydrogen addition to C2 of the adenine moiety; and MTMA6, the species formed by net hydrogen addition to C8 of the adenine moiety. Radical MTMA3, the O4-protonated thymine anion, was clearly detected at 10 K, but upon thermal annealing at 40 K the lines began to disappear. In crystals irradiated at 65 K MTMA3 was only weakly present. Radical MTMA2 decayed at about 250 K with no detectable successor, and radical MTMA5 disappeared at about 180 K. It was not possible to learn from the d ata if MTMA5 transformed into MTMA6. The radical distribution in the 1-methylthymine.9-methyladenine crystal system is different from that in crystals of the individual components. Reasons for this behavior are discussed in light of the hydrogen bonding schemes and molecular stacking interactions in each of the crystals. An important feature is the concept of excited-state transfer from the adenine to the thymine moiety, followed by dehydrogenation at the thymine Nl-methyl group, the mechanism resulting in radical MTMA2.

Free radical formation in X-irradiated crystals of 2'-deoxycytidine hydrochloride. Electron magnetic resonance studies at 10 K.

Single crystals of deoxycytidine hydrochloride (CdR.HCl) have been X-irradiated at 10 K with doses up to about 150 kGy and studied using 24 GHz (K-band) EPR, ENDOR and FSE spectroscopy. In this system, the cytosine base is protonated at the N3 position. Nine different radicals were characterized and identified. Three of these are ascribed to three versions of the one-electron reduced species, probably differing in their protonation state. Radicals formed by net hydrogen addition to the cytosine C5 and C6 positions were observed at 10 K. The hydrogen-abstraction radical at the deoxyribose C1' position most probably results from initial oxidation of the base. The remaining radical species are all localized to the sugar moiety, representing products formed by net hydrogen abstraction from three of the five available carbons of the deoxyribose sugar. The lack of base-centered oxidation products as well as the structures of the one-electron reduced species is rationalized by considering the specific proton donor-acceptor properties of this crystalline lattice in comparison with similar systems.

Electron spin resonance and electron nuclear double resonance study of X-irradiated deoxyadenosine: proton transfer behavior of primary ionic radicals.

A study of deoxyadenosine crystals (anhydrous form) after irradiation at 10 K found four base-centered radicals and one sugar-centered radical. Radical R1, thermally stable to about 100 K and photobleachable easily with white light, was the product of deprotonation at the amino group by the primary radical cation. Radical R2, also thermally stable to about 100 K, was the product of protonation at N3 of the primary radical anion. Radical R3, stable to about 170 K, was centered in the deoxyribose moiety and evidently was the result of net hydrogen abstraction from C4'. Radicals R4 and R5 were the C2 and C8 H-addition products with couplings typical of those species. Both R4 and R5 were formed at 10 K and were stable at room temperature. The behavior of R1 in several systems provides additional evidence for significant involvement of the hydrogen-bonding environment in controlling the stabilization (or formation) of radicals resulting directly from ionization, as described previously (Radiat. Res. 131, 272-284, 1992). From comparison of amino-group hydrogen-bonding environments in which radicals with the structure of R1 were stabilized, we conclude that oxygen atoms as proton acceptors are important in permitting the charge and spin separation necessary for radical stabilization. In particular, oxygens of ROH structures seem most efficient by readily permitting a multi-proton shuffle through a mechanism amounting to proton exchange. The collective results show that stabilization of these products is unlikely unless the charge and spin can be separated by at least one intervening molecule.

Electron paramagnetic resonance and electron nuclear double resonance studies of X-irradiated crystals of cytosine hydrochloride. Part I: free radical formation at 10 K after high radiation doses.

Anhydrous single crystals of cytosine hydrochloride (protonated at N3) have been X-irradiated at 10 K and studied using K-band EPR, ENDOR and FSE spectroscopy. At least seven radicals were present at 10 K after X irradiation with a dose of about 150 kGy. Two different protonation states of the one-electron reduced cytosine cation were observed: an amino-protonated species (R1) and the pristine one-electron reduced species (R2) with zero net charge. Apparently three deprotonated versions of the one-electron oxidized cytosine cation were formed: the amino-deprotonated cation (R3), an N3-deprotonated cation (R4) and an N1-deprotonated cation (R5). Finally, two products formed by net hydrogen addition to the cytosine base were observed: a C5 hydrogen-addition radical (R6) and a C6 hydrogen-addition radical (R7). The crystalline lattice of cytosine hydrochloride is characterized in part by a cytosine base initially protonated at the N3-position, thus forming a cytosine base cation, and in part by an extended network of hydrogen bonding involving the chlorine anions. Proton transfer properties of pristine one-electron oxidation and reduction base products in this lattice are discussed and are suggested as explanations of the unusual multitude of positions for deprotonation of the one-electron oxidized species as well as for the two protonation states of the reduction product observed. The magnetic parameters for the amino-protonated species R1 agree well with those extracted from previous studies of cytosine derivatives in frozen solutions and in various glasses.

Radiation damage to DNA base pairs. II. Paramagnetic resonance studies of 1-methyluracil x 9-ethyladenine complex crystals X-irradiated at 10 K.

Single crystals of the co-crystalline complex of 1-methyluracil and 9-ethyladenine were X-irradiated and studied using EPR, ENDOR and FSE spectroscopic techniques at 10 K. All together seven radicals were identified, and experimental evidence for at least one more species, as well as for a very low population of radical pairs, is available. Oxidation and reduction products appear to be stabilized at both base constituents of the pair. Of the 1-methyluracil moiety, the product formed by net hydrogen abstraction from the methyl group was observed, together with the 1-methyluracil anion and the 1-methyluracil-5-yl radical. From the 9-ethyladenine moiety, the N3-protonated 9-ethyladenine anion is stabilized. In addition, the 9-ethyladenine cation as well as traces of the amino-deprotonated cation were observed, together with the C8-H hydrogen adduct. The presence of oxidation and reduction products in each of the two bases may indicate that negligible energy transfer takes place between them. This behavior is different from that observed in the similar pair of 1-methylthymine-9-methyladenine. There also seems to be minor proton exchange between the two stacks of molecules: Interbase protonation-deprotonation channeled through the hydrogen-bonding scheme seems to be almost completely suppressed.