Levels of monocyte reactive oxygen species are associated with reduced natural killer cell activity in major depressive disorder.

Major depressive disorder (MDD) is associated with reductions in natural killer cell activity (NKCA), however the mechanism(s) mediating reduced NKCA in MDD has yet to be determined. In light of evidence that MDD is associated with an inflammatory immune response, we propose that reactive oxygen species (ROS), generated by inflammatory leukocytes (monocytes and/or neutrophils), may mediate the suppression of NKCA in MDD. Intracellular levels of monocyte ROS were significantly associated with reductions in NKCA in outpatients (n = 15) diagnosed with MDD. Sleep disturbance was also significantly correlated with reductions in NKCA. Elevated levels of ROS may be an additional characteristic of a subset of depressed patients in whom an inflammatory response persists and elevations in ROS may, in part, mediate the associations observed between MDD, cardiovascular disease, and cancer.

Selective dopaminergic vulnerability: 3,4-dihydroxyphenylacetaldehyde targets mitochondria.

Parkinson's disease (PD) is a major cause of age-related morbidity and mortality, present in nearly 1% of individuals at ages 70-79 and approximately 2.5% of individuals at age 85. L-DOPA (L-dihydroxyphenylalanine), which is metabolized to dopamine by dopa decarboxylase, is the primary therapy for PD, but may also contribute to disease progression. Association between mitochondrial dysfunction, monoamine oxidase (MAO) activity, and dopaminergic neurotoxicity has been repeatedly observed, but the mechanisms underlying selective dopaminergic neuron depletion in aging and neurodegenerative disorders remain unclear. We now report that 3,4-dihydroxyphenylacetaldehyde (DOPAL), the MAO metabolite of dopamine, is more cytotoxic in neuronally differentiated PC12 cells than dopamine and several of its metabolites. In isolated, energetically compromised mitochondria, physiological concentrations of DOPAL induced the permeability transition (PT), a trigger for cell death. Dopamine was > 1000-fold less potent. PT inhibitors protected both mitochondria and cells against DOPAL. Sensitivity to DOPAL was reduced > or = 30-fold in fully energized mitochondria, suggesting that mitochondrial respiration may increase resistance to PT induction by the endogenous DOPAL in the substantia nigra. These data provide a potential mechanism of action for L-DOPA-mediated neurotoxicity and suggest two potentially interactive mechanisms for the selective vulnerability of neurons exposed to dopamine.

Catecholamine monoamine oxidase a metabolite in adrenergic neurons is cytotoxic in vivo.

3,4-Dihydroxyphenylglycolaldehyde is the monoamine oxidase-A metabolite of two catecholamine neurotransmitters, epinephrine and norepinephrine. This aldehyde metabolite and its synthesizing enzymes increase in cell bodies of catecholamine neurons in Alzheimer's disease. To test the hypothesis that 3,4-dihydroxyphenylglycolaldehyde, but not epinephrine or its major metabolite 4-hydroxy-3-methoxyphenylglycol, is a neurotoxin, we injected 3,4-dihydroxyphenylglycolaldehyde onto adrenergic neurons in the rostral ventrolateral medulla. Injections of epinephrine or 4-hydroxy-3-methoxyphenylglycol were made into the same area of controls. A dose response and time study were performed. Adrenergic neurons were identified by their content of the epinephrine synthesizing enzyme, phenylethanolamine N-methyltransferase, immunohistochemically. Apoptosis was evaluated by in situ terminal deoxynucleotidyl-transferase mediated dUTP nick end label staining. Injection of 3,4-dihydroxyphenylglycolaldehyde in amounts as low as 50 ng results in loss of adrenergic neurons and apoptosis after 18 h. The degree of neurotoxicity is dose and time dependent. Doses of 3,4-dihydroxyphenylglycolaldehyde 10-fold higher produce necrosis. Neither epinephrine nor 4-hydroxy-3-methoxyphenylglycol are toxic. A 2.5 microg injection of 3,4-dihydroxyphenylglycolaldehyde is toxic to cortical neurons but not glia. Active uptake of the catecholamine-derived aldehyde into differentiated PC-12 cells is demonstrated. Implications of these findings for catecholamine neuron death in neurodegenerative diseases are discussed.

Norepinephrine transmitter metabolite generates free radicals and activates mitochondrial permeability transition: a mechanism for DOPEGAL-induced apoptosis.

3,4-Dihydroxyphenylglycolaldehyde (DOPEGAL) is the monoamine oxidase A metabolite of norepinephrine (NE) and epinephrine. DOPEGAL, but neither NE nor its other metabolites induces apoptosis in differentiated PC-12 cells by an unknown mechanism. To study the mechanism of DOPEGAL-induced apoptosis, we tested DOPEGAL and NE for their capacity to generate free radicals and to induce mitochondrial permeability transition (PT). Results show that DOPEGAL but not NE forms reactive free radical intermediates under oxidative stress and enhances Ca2+-mediated induction of the mitochondrial PT. Linkage of these events to apoptosis is described. Implications for degenerative diseases are discussed.

Norepinephrine transmitter metabolite induces apoptosis in differentiated rat pheochromocytoma cells.

3,4-Dihydroxyphenylglycolaldehyde (DOPEGAL) is the monoamine oxidase A metabolite of norepinephrine and epinephrine. DOPEGAL, but not other metabolites, kills differentiated PC-12 cells. However, the type of DOPEGAL induced cell death, whether necrosis or apoptosis, is not known. To determine the type of cell death triggered by DOPEGAL, PC-12 cells cultured in the presence or absence of 30 microM DOPEGAL were examined by electron microscopy and DNA agarose gel electrophoresis for characteristic features of apoptosis. Results indicate that DOPEGAL induces apoptosis in these cells. Implications for degenerative diseases are discussed.

Norepinephrine transmitter metabolite is a selective cell death messenger in differentiated rat pheochromocytoma cells.

3,4-Dihydroxyphenylglycolaldehyde (DOPEGAL) is the monoamine oxidase A (MAO-A) metabolite of norepinephrine (NE) and epinephrine (Epi). Oxidative metabolites of amines are predicted toxins. In this study we determine the toxicity of DOPEGAL, its tautomer 2',3,4-trihydroxyacetophenone (THAP) as well as NE, Epi and their oxidative and methylated metabolites in cultures of differentiated PC-12 cells. At 59.5 microM DOPEGAL, THAP and Epi, but not NE or other NE or Epi metabolites decreased PC-12 cells by 43.8%, 26.7% and 16.8% respectively. DOPEGAL toxicity was concentration and time dependent. Possible implications for degenerative diseases are discussed.

Amplitude/intensity functions of auditory event-related potentials predict responsiveness to bupropion in major depressive disorder.

Patients diagnosed with major depressive disorder (MDD) and enrolled in an open-label safety surveillance study of a sustained release formulation of bupropion hydrochloride (100 to 300 mg/day) were evaluated with the Hamilton Rating Scale for Depression (HAM-D) immediately before and 6 to 12 weeks after the initiation of drug treatment. Auditory event-related potentials (ERPs) recorded under a stimulus intensity modulation paradigm were also obtained at these times. Patients were classified as responders and nonresponders based on post-treatment HAM-D scores, with responders having HAM-D scores less than 10 and nonresponders having scores greater than 10. Consistent with our previous findings, responders exhibited significantly larger positive slope coefficients for P2 ERP component amplitudes as a function of auditory stimulus intensity obtained at baseline and were not affected by bupropion treatment. Thus, these results further support our previous finding that ERP amplitude/intensity functions measured under a stimulus intensity modulation paradigm provide information about the likelihood of a positive therapeutic response to antidepressant pharmacotherapy in patients with MDD and extends these results to bupropion, a pharmacologically atypical antidepressant agent.

Taxol protects against calcium-mediated death of differentiated rat pheochromocytoma cells.

Elevated levels of intraneuronal calcium may contribute to neuronal death in both Alzheimer's disease and stroke. In part, this neuronal death may be due to calcium-induced disruption of microtubules and inhibition of axonal transport. Taxol stabilizes microtubules to disaggregation. To determine whether taxol could protect against calcium-mediated neuron cell death, a test system was established using a nerve growth factor-differentiated rat pheochromocytoma cell line (PC12 cells). PC12 cells were cultured with nerve growth factor to induce a neuronal phenotype. After 15 days, the cells were exposed to taxol, the calcium ionophore, A23187, or taxol plus ionophore for up to 24 h. Taxol alone reduced cell survival in a concentration dependent manner. At a concentration of 50 nM survival was reduced to between 63% and 84% of control after 4 h of exposure. The ionophore (1 microM) variably reduced cell survival to between 10 and 55% at 4h. However, when taxol was added to the ionophore the cell survival was significantly increased by 1.5 to 4-fold. The protective effect of taxol lasted up to 24h. We conclude that taxol has a protective effect on calcium-mediated neurotoxicity. Drugs targeting underlying cellular mechanisms involved in calcium-mediated neuronal death may lead to successful therapy for Alzheimer's disease and stroke.

Occurrence of cancer in Alzheimer and elderly control patients: an epidemiologic necropsy study.

Epidemiologic necropsy provides an accurate measure of the occurrence rates of diseases. To determine the occurrence of cancer in Alzheimer patients as well as in non-Alzheimer elderly controls, we examined autopsy reports of 575 control and 71 Alzheimer cases aged 50-100 years for histologic evidence of cancer. We compared expected rates of cancers calculated from the National Cancer Institute's Surveillance, Epidemiology and End Result (SEER) Program data to rates observed at autopsy using a chi-squared test. To determine whether there was an association between the occurrence of cancer and Alzheimer disease, we compared rates for all cancer and three specific cancers in Alzheimer and control patients using an odds ratio test. We found from fourfold to 98-fold more cancer in Alzheimer patients and controls than that expected from SEER data. There was no statistical difference in the autopsy incidence of total, lung, or prostate cancer between Alzheimer patients and controls. However, the occurrence of pancreatic cancer was 6.7-fold higher in Alzheimer patients than in control subjects. Controlling for multiple comparisons, the odds ratio for pancreatic cancer in Alzheimer's disease was significantly higher than in controls (p < 0.001). Our results indicate that cancer occurs more frequently than expected in both Alzheimer patients and control subjects. In addition, there may be an association between the occurrence of certain cancers and Alzheimer's disease.

Validation of a telephone version of the mini-mental state examination.

OBJECTIVE: To assess the construct validity of a telephone-administered version of the Mini-Mental State Examination (MMSE). DESIGN: Validity testing by comparing a telephone version of the MMSE administered first to a face-to-face evaluation done several days later. SETTING: Outpatient geriatric assessment center. SUBJECTS: 100 of 175 consecutive referrals. MAIN OUTCOME MEASURES: MMSE and a brief neuropsychological screening test (BNPS) face-to-face and a telephone version of the MMSE as part of the Adult Lifestyles and Function Interview (ALFI-MMSE). RESULTS: Test scores of the two MMSE versions correlated strongly for all subjects (Pearson's r = 0.85, P = 0.001) and remained significant for the cognitively intact (P = 0.02) and questionably (P = 0.002), mildly (P = 0.0001), and moderately (P = 0.003) demented. Comparison of the two versions' equivalent 22 items revealed no significant difference for scores of all subjects (P = 0.07) but with a trend toward higher scores in the original version. Diminished hearing, reported either by the subject (P = 0.003) or by the collateral source (P = 0.02) was associated with lower scores on the telephone version. Five individual test items were biased by the route of test administration. Sensitivity and specificity relative to the BNPS were 67% and 100% for the ALFI-MMSE and 68% and 100% for the MMSE, respectively. CONCLUSION: The scores on the ALFI-MMSE correlated strongly with the scores of the original version given face-to-face in subjects undergoing geriatric assessment. The results indicate that the ALFI-MMSE could be a useful and economical tool to screen for cognitive impairment.

The neurological features of early and 'latent' human immunodeficiency virus infection.

Neurological manifestations of unknown cause occurring in patients who become or are HIV antibody positive with presumed normal immune function have been described recently. This report adds a further six cases, all of whom had normal CD4+ cell counts either throughout the period of observation or after the episode of seroconversion. Three had an acute presentation, two in the context of documented seroconversion consisting of one of the following: an encephalitis, an ataxia, and confusion with neuralgic amyotrophy. Three had a subacute disorder occurring at a later phase of HIV infection but before opportunistic infections or neoplasms, and marked by a static mild cognitive deficit. This report extends the range of abnormalities that may be seen at seroconversion and documents the presence of a non-progressive cognitive deficit occurring in the latent phase of HIV infection.

A highly sensitive assay for phenylethanolamine N-methyltransferase in human brain.

A rapid, highly sensitive assay for phenylethanolamine N-methyltransferase in brain using the natural substrate, norepinephrine, is described. The method is based on the selective adsorption and elution of the reaction product, epinephrine, from alumina. A small but important further lowering of blanks and increase in sensitivity is attained by removal of the radiolabeled substrate, [methyl-3H]-S-adenosylmethionine by precipitation as the reineckate prior to adsorption of norepinephrine to alumina. The assay has a sensitivity of 30 fmole and the PNMT activity could be measured in as little as 1 mg (wet wt) of human locus coeruleus tissue. The sensitivity is enhanced by homogenizing tissue in small volumes and removing potential inhibitors by dialysis. We report for the first time PNMT activity in specific regions of the human cerebral and cerebellar cortex.

Decrease in tyrosine hydroxylase synthesis in cultured adrenal medulla by N6-methyladenosine.

Explants of adrenal medullae were cultured in defined media for up to 22 hr, during which time the tissue remained histologically intact. Addition of N6-methyladenosine to the medium led to a diminution in the activity of tyrosine hydroxylase (EC 1.14.16.2) in the tissue. The enzyme activity was inversely proportional to the concentration of N6-methyladenosine in the culture medium. The extent of loss of tyrosine hydroxylase, as measured by immunochemical titration, corresponded to the degree of loss in enzyme activity under the same conditions. The decreased amount of enzyme protein was due to a decreased rate of synthesis of tyrosine hydroxylase. A significant decrease in the relative rate of tyrosine hydroxylase synthesis indicates the selectivity of this effect of N6-methyladenosine. The rate of enzyme degradation was not affected by this compound. Neither adenosine, N6-cyclohexyladenosine, nor several other methylated nucleosides including N1-methyladenosine, N7-methylguanosine and N2-methylguanosine had an effect on the enzyme. However, two other N6-substituted adenosines, N6-dimethyladenosine and N6-gamma gamma-dimethylallyladenosine, were effective in reducing tyrosine hydroxylase. The results are consistent with the view that specific substitutions at the N6 position of adenosine could play a role in regulation of levels of tyrosine hydroxylase by altering its rate of biosynthesis.

Effects of N6-methyladenosine on the synthesis of phenylethanolamine N-methyltransferase in cultured explants of rat adrenal medulla.

Explants of adrenal medullae were cultured in defined media for up to 48 h, during which time the tissue remained histologically intact. Addition of N6-methyladenosine to the medium led to a diminution in the activity of phenylethanolamine N-methyltransferase (EC 2.1.1.28) in the tissue. The enzyme activity was inversely proportional to the concentration N6-methyladenosine in the culture medium. The extent of loss of phenylethanolamine N-methyltransferase, as measured by immunochemical titration, corresponded to the degree of loss in enzyme activity under the same conditions. Furthermore, the decreased amount of enzyme protein was due to a decrease in the rate of synthesis of phenylethanolamine N-methyltransferase. Neither adenosine nor several methylated nucleosides, including 7-methylguanosine, N2-methylguanosine, and 5-methylcytosine, had an effect on the enzyme. Two other adrenal medullary enzymes, monoamine oxidase (EC 1.4.3.4) and acid phosphatase (EC 3.1.3.2), were not affected by addition of N6-methyladenosine to the medium. The results are consistent with the view that this effect of N6-methyladenosine on the concentration of phenylethanolamine N-methyltransferase is due to an inhibition of its biosynthesis rather than to an alteration of its rate of degradation.

Insulin-induced enhancement of uptake of noradrenaline in atrial strips.

1 Addition of insulin to the organ bath increased the force of contraction of guinea-pig left atrial strips driven electrically at 1 Hz. 2 The positive inotropic response to insulin remained unaltered in atria depleted of catecholamine or when beta-adrenoceptors were blocked by addition of propranolol to the organ bath. 3 The response os isolated atria to noradrenaline was significantly reduced in the presence of insulin. 4 Insulin affected neither the calcium accumulating abilities of the heart sarcolemma, mitochondria or microsomes, nor the cyclic adenosine 3',5'-monophosphate (cyclic-AMP)-protein kinase-induced stimulation of microsomal calcium uptake. 5 Addition of insulin to the organ bath enhanced significantly the ability of the cardiac tissue to take up [3H]-noradrenaline as well as [3H]-metaraminol. The activities of monoamine oxidase and catechol-O-methyl transferase were not changed after addition of insulin to homogenates of the heart. 6 The ability of insulin to facilitate uptake of noradrenaline would be expected to cause a decrease in the amount of the amine reaching the receptors, thus leading to a diminished response to this amine. This may explain, at least in part, insulin-induced subsensitivity to noradrenaline. 7 This view is supported by the observation that after blockade of amine uptake by destruction of nerve terminals, insulin failed to reduce the positive inotropic response to noradrenaline.

Hypoglycaemia secondary to pancreatic islet cell adenoma.

The detailed case histories of 5 patients with hypoglycaemic episodes secondary to islet cell adenoma of the pancreas are presented. Clinical recognition of this syndrome remains the major problem but a full and detailed medical history is usually strongly suggestive of the correct diagnosis. The clinical diagnosis is confirmed by the repeated demonstrated that: 1) Symptomatic episodes produced by fasting are in fact due to hypoglycaemia (plasma glucose level less than 2.5 mmol/litre) 2) Such episodes are relieved by glucose administration 3) Concomitant hyperinsulinaemia is present (serum insulin greater than 8 micro-units/ml in the fasting state). Surgical resection of the adenoma produces a complete cure but the identification of the lesion at operation may be difficult and preoperative means of accurate localisation may be needed.