Four unique monoclonal antibodies to the putative receptor binding domain of erythropoietin inhibit the biological function of the hormone

We have produced a series of monoclonal antibodies (MoAbs) to amino acid region 99-129 of human erythropoietin (Epo) that distinguish unique structural features within this putative receptor binding domain of the hormone. The MoAbs recognize denatured Epo with widely different sensitivities on a Western blot and differentially bind to native Epo in solution. In addition, three of the four MoAbs neutralize the biological activity of Epo in a concentration-dependent fashion in vitro. Neutralization was measured both by inhibition of Epo-induced differentiation in Rauscher murine erythroleukemia cells and by inhibition of Epo-induced proliferation in normal murine splenic erythroid precursors. Characterization of the structural epitopes recognized by each of these four reagent MoAbs should provide us with important information concerning the requirements for hormone-receptor interaction.

A psychobiological perspective on the personality disorders

A preliminary but growing body of evidence supports the existence of genetic and biological substrates of personality, suggesting the utility of a psychobiological perspective on the personality disorders. The investigation of biological correlates of personality disorders can provide an empirical base to explore the relationship between biological predispositions and psychological function. The authors propose a psychobiological model based on dimensions of cognitive/perceptual organization, impulsivity/aggression, affective instability, and anxiety/inhibition. These dimensions span the DSM-III-R axis I and axis II disorders. The authors review phenomenological, genetic, and biological evidence in relation to each of these dimensions. Although such an approach remains heuristic, this model provides a promising vantage point from which to generate investigation of the development and treatment of the personality disorders.

Dopamine in schizophrenia: a review and reconceptualization

OBJECTIVE

The initial hypothesis that schizophrenia is a manifestation of hyperdopaminergia has recently been faulted. However, several new findings suggest that abnormal, although not necessarily excessive, dopamine activity is an important factor in schizophrenia. The authors discuss these findings and their implications.

METHOD

All published studies regarding dopamine and schizophrenia and all studies on the role of dopamine in cognition were reviewed. Attention has focused on post-mortem studies, positron emission tomography, neuroleptic drug actions, plasma levels of the dopamine metabolite homovanillic acid (HVA), and cerebral blood flow.

RESULTS

Evidence, particularly from intracellular recording studies in animals and plasma HVA measurements, suggests that neuroleptics act by reducing dopamine activity in mesolimbic dopamine neurons. Post-mortem studies have shown high dopamine and HVA concentrations in various subcortical brain regions and greater than normal dopamine receptor densities in the brains of schizophrenic patients. On the other hand, the negative/deficit symptom complex of schizophrenia may be associated with low dopamine activity in the prefrontal cortex. Recent animal and human studies suggest that prefrontal dopamine neurons inhibit subcortical dopamine activity. The authors hypothesize that schizophrenia is characterized by abnormally low prefrontal dopamine activity (causing deficit symptoms) leading to excessive dopamine activity in mesolimbic dopamine neurons (causing positive symptoms).

CONCLUSIONS

The possible co-occurrence of high and low dopamine activity in schizophrenia has implications for the conceptualization of dopamine's role in schizophrenia. It would explain the concurrent presence of negative and positive symptoms. This hypothesis is testable and has important implications for treatment of schizophrenia and schizophrenia spectrum disorders.

Effects of neuroleptic treatment on symptoms of schizophrenia and plasma homovanillic acid concentrations

Measurement of plasma concentrations of the dopamine metabolite, homovanillic acid, is an indirect tool to assess changes in dopamine turnover in schizophrenic patients. Plasma homovanillic acid concentrations have been reported to decrease during neuroleptic treatment, with the decrement correlating with symptomatic improvement in symptoms of schizophrenia. The present study tested the hypothesis that neuroleptic drugs decrease plasma homovanillic acid concentrations in those schizophrenic patients who improve with administration of neuroleptic drugs but not in patients who fail to display a treatment response. Twenty schizophrenic men who remained drug free for at least 2 weeks were treated with 20 mg/d of haloperidol for 5 weeks. Symptoms and plasma homovanillic acid concentrations were assessed on the last drug-free day and weekly for 5 weeks. Mean plasma homovanillic acid concentrations decreased in the group of patients who responded to neuroleptic treatment and did not change in the group of patients who did not improve. These findings suggest that there may be a qualitative distinction between responders and nonresponders to dopamine antagonists.

Plasma homovanillic acid in schizotypal personality disorder

Schizotypal patients were found to have a significantly higher mean plasma HVA concentration than normal comparison subjects. Furthermore, plasma HVA concentration positively correlated with "psychotic-like" schizotypal symptoms. These results implicate dopaminergic mechanisms modulating the psychotic-like symptoms of schizotypal personality disorder.

Time course and clinical predictors of treatment response in schizophrenia

The severity of schizophrenic symptoms was examined in 50 male chronic patients while neuroleptic free for at least 3 weeks and during 6 weeks of treatment with haloperidol. The results suggested that 50% of the improvement associated with haloperidol administration occurred by the end of the first treatment week and that early improvement, at both 1 and 4 weeks of treatment, was predictable from drug-free symptom severity. There was a negative correlation between week 1 improvement and improvement during the next 3 weeks of treatment, suggesting that medication response is not linear. Finally, dose increases after 4 weeks of treatment with 20 mg of haloperidol did not lead to any clinical improvement. These results are discussed in terms of their implications for selecting chronic schizophrenic patients who will and will not benefit from medication treatment.

Brief neuroleptic discontinuation and clinical symptoms in Kraepelinian and non-Kraepelinian chronic schizophrenic patients

Neuroleptic medication was abruptly discontinued in 24 male chronic schizophrenic patients who were subdivided on the basis of their history of illness into Kraepelinian (n = 8) and non-Kraepelinian (n = 16) subgroups. These patients were kept drug free for 6 weeks and then returned to treatment with haloperidol, 20 mg/day. Half of the non-Kraepelinian patients developed exacerbations of their symptoms, which quickly resolved when they were returned to medication, while none of the Kraepelinian patients showed a worsening of symptomatology. On-medication clinical severity failed to predict risk for exacerbation, with severity of exacerbation predicting the amount of improvement when returned to medication. The Kraepelinian patients were found to be much less variable than the non-Kraepelinian patients in their symptoms during both medication manipulations, suggesting that medication truly has a negligible effect on them.

Reactive oxygen metabolites inhibit spontaneous lymphatic contractions

The effects of oxygen-derived free radicals on the contractile activity of the mesenteric collecting lymphatics were evaluated in the anesthetized rat. Lymphatic contractions were monitored before, during and after the application of oxyradicals. Contraction frequency (F), stroke volume (SV), ejection fraction (EF), contraction propagation (PC), and lymph pump flow (LPF) were determined from the lymphatic diameter tracings. Oxyradicals were generated using hypoxanthine and xanthine oxidase. Exposure to oxyradicals inhibited the lymphatic pumping mechanism: 1) F fell from 15.5 +/- 0.8 to 0.8 +/- 0.7 beats/min; 2) EF went from 0.44 +/- 0.02 to 0.08 +/- 0.04; 3) PC dropped from 92 +/- 2 to 56 +/- 8%; and 4) LPF fell precipitously from 41.0 +/- 5.2 to 0.7 +/- 0.4 nl/min. The effects of the oxyradicals were attenuated by superoxide dismutase, implicating superoxide anion as one of the predominant causative agents. We conclude that oxyradicals significantly inhibit the lymph pump and that this inhibition could be a factor contributing to the formation of interstitial edema during inflammation.

Increased biosynthesis of Alzheimer amyloid precursor protein in the cerebral cortex of rats with lesions of the nucleus basalis of Meynert

The nucleus basalis of Meynert was lesioned by infusion of N-methyl-D-aspartate (NMDA) unilaterally in adult rat brain. Seven days post lesion we observed that polysomes isolated from the cerebral cortex affected by the lesion synthesized 2.6-fold greater amounts of the Alzheimer amyloid precursor protein (AAPP) compared to the nonlesioned side of the same rat brain. This increase exhibited specificity to AAPP in that overall protein synthesis was not altered by the lesion. The increase of AAPP did not alter the ratio of AAPP isotypes in rat brain (in which AAPP 695, which is lacking the protease inhibitor insert remains the predominant form). The increased synthesis did not result in the apparent accumulation of mature AAPP. These results indicate that a cholinergic lesion which models many of the neurochemical changes observed in Alzheimer's disease induces the expression of AAPP in a major projection region, the cerebral cortex.

Diagnostic issues in chronic schizophrenia: kraepelinian schizophrenia, undifferentiated schizophrenia, and state-independent negative symptoms

Data are presented concerning three recent clinical distinctions in schizophrenia: kraepelinian versus non-kraepelinian patients; mixed versus simple undifferentiated subtypes; and state-dependent versus state-independent negative symptoms. Schizophrenic patients who have been ill and dependent on others for the past 5 years ('kraepelinians') were compared to other chronic schizophrenics. The kraepelinian patients met the criteria for schizophrenia by more diagnostic systems than other patients, were less responsive to haloperidol, had more severe negative symptoms and formal thought disorder, and had similarly severe positive symptoms. They also had cerebral ventricles that demonstrated more left-to-right asymmetry and a greater family history of schizophrenia spectrum disorders. Mixed undifferentiated schizophrenic patients, who met criteria for more than one schizophrenic subtype, were compared to simple undifferentiated schizophrenic patients, who met criteria for no subtype. The mixed group was characterized by more severe positive and negative symptoms and formal thought disorder, worse social functioning, and a worse response to haloperidol. In a subgroup of patients who were studied once while in a state of exacerbation and once while in a state of relative remission, the negative symptoms of inattention and affective flattening were state-dependent, while anhedonia-asociality was state-independent.

Pharmacological alleviation of combined cholinergic/noradrenergic lesion-induced memory deficits in rats

Data derived from a number of preclinical studies examining the effects of combined cholinergic and noradrenergic lesions in a rat model of Alzheimer's disease are reviewed. Results from these studies indicated that a nucleus basalis of Meynert (nbM) lesion combined with a lesion of the ascending noradrenergic bundle (ANB) did not exacerbate 72-h passive avoidance retention deficits beyond the degree of impairment produced by nbM lesions alone. However, the addition of an ANB lesion did block the efficacy of two choiinomimetics (physostigmine and oxotremorine) to reverse the lesion-induced memory impairment. Memory in combined lesioned rats was restored when cholinomimetic therapy was administered in combination with low doses of clonidine. Studies investigating a number of Hoechst-Roussel Pharmaceuticals compounds have produced memory-enhancing effects in animals prepared with combined nbM/ANB lesions without the need for clonidine supplementation. These compounds include P128, P86-7493, and P87-8184. Moreover, these compounds have also been shown to be effective in reversing passive avoidance memory deficits in animals with nbM lesions and treated with the noradrenergic toxin DSP-4. Implications for pharmacotherapeutic approaches for the treatment of Alzheimer's disease are discussed.

Platelet phospholipid synthesis in Alzheimer's disease

The rates of incorporation of [3H]choline and [3H]ethanolamine into membrane phospholipids of platelets from 22 drug-free Alzheimer's disease patients and 18 normal elderly controls were compared. No significant differences between groups were found. If alterations in lipid metabolism are involved in the pathophysiological processes underlying Alzheimer's disease, such alterations are not manifest in measures of radiolabeled base incorporation into platelet phospholipids.

Effects of indomethacin on plasma homovanillic acid concentration in normal subjects: a study of prostaglandin-dopamine interactions

In laboratory animals, prostaglandins have been shown to act as endogenous neuromodulators of central dopamine (DA) activity. To examine the interaction between prostaglandins and DA in man, the effect of a prostaglandin synthesis inhibitor, indomethacin, was studied on plasma concentrations of the DA metabolite, homovanillic acid (pHVA). Indomethacin (150 mg PO) as compared to placebo significantly elevated mean pHVA concentrations in eight normal subjects. Results of this study support the hypothesis that, as in animals, inhibition of prostaglandin synthesis increases central DA turnover in man.

Changes in plasma homovanillic acid concentrations in schizophrenic patients following neuroleptic discontinuation

Changes in plasma levels of the dopamine metabolite homovanillic acid have been reported to correlate with changes in the severity of schizophrenic symptoms during neuroleptic administration and after neuroleptic discontinuation. This study examined the effects of discontinuation of neuroleptic treatment on plasma homovanillic acid levels in 23 patients with chronic schizophrenia. It was hypothesized that clinical decompensation would be associated with increased plasma homovanillic acid levels. Plasma homovanillic acid was measured during administration of neuroleptic medication and during a subsequent 6-week drug-free period. Nine patients decompensated during the drug-free period and 14 patients did not. Following drug discontinuation, plasma homovanillic acid concentrations were higher in schizophrenic patients who decompensated than in those who did not. Furthermore, peak plasma homovanillic acid elevation after discontinuation of neuroleptic medication was significantly correlated with peak Brief Psychiatric Rating Scale increase. The data suggest that, in some schizophrenic patients, symptomatic decompensation after discontinuation of neuroleptic treatment is associated with increases in dopamine turnover.

Attentional markers of vulnerability to schizophrenia: performance of medicated and unmedicated patients and normals

Medicated and unmedicated schizophrenic patients (both n's = 14) were compared to a normal control sample (n = 15) on two attentional tasks hypothesized to be markers of vulnerability to schizophrenia. These tasks, the continuous performance test and the visual backward masking task, were found to be more deviant in schizophrenic patients than in normals. In addition, the group mean levels of performance did not differ consistently across medication status within the medicated patients. It was found, however, that the association between these tasks varied as a function of medication status, with unmedicated patients more similar to normals than to medicated patients. The implications of these results for the two tasks as markers are discussed, with special focus on those earlier studies that did not evaluate unmedicated patients.

Hormonal stimulation of 12(R)-HETE, a cytochrome P450 arachidonic acid metabolite in the rabbit cornea

12(R)-HETE [12(R)-hydroxy-5, 8, 10, 14 eicosatetraenoic acid] is one of the major arachidonic acid metabolites produced by microsomal cytochrome P450 of the corneal epithelium. This metabolite is a potent inhibitor of Na(+)-K(+)-ATPase activity in several tissues. We investigated endogenous production of 12(R)-HETE in the rabbit corneal epithelium. Incubation of corneal epithelial sheets (prelabeled with 14C-arachidonic acid) with arginine vasopressin resulted in the production of radioactive 12(R)-HETE suggesting its formation from endogenously labeled-arachidonic acid. The maximal response was obtained with 1 microM arginine vasopressin and represents a 15-fold increase in 12(R)-HETE formation compared with that of control tissues. Stimulation of 14C-arachidonic acid release with a detergent, digitonin, also resulted in endogenous 12(R)-HETE formation. Analysis of the incubation media following digitonin treatment of prelabeled corneal epithelial sheets revealed that 12(R)-HETE production was maximal at 20 microM digitonin, a 17-fold increase over control values. This study is the first to describe hormonal and traumatic stimulation of 12(R)-HETE formation from endogenously labeled arachidonic acid in intact corneal tissues. This study demonstrates that the formation of this Na(+)-K(+)-ATPase inhibitor can be modulated by physiological and pathophysiological regulation.

Increased morbid risk for schizophrenia-related disorders in relatives of schizotypal personality disordered patients

To evaluate whether probands from a clinical sample diagnosed as having DSM-III schizotypal and/or paranoid personality disorder have a familial relationship to the schizophrenia-related disorders, the morbid risk for schizophrenia-related disorders and other psychiatric disorders were evaluated in the first-degree relatives of patients with schizotypal and/or paranoid personality disorder and compared with the corresponding risk for these disorders in the first-degree relatives of patients with other non-schizophrenia-related personality disorders. The morbid risk for all schizophrenia-related disorders, and specifically for schizophrenia-related personality disorders, was significantly greater among the relatives of the probands with schizotypal and/or paranoid personality disorder than among the relatives of probands with other personality disorder. The morbid risk for other psychiatric disorders did not differ significantly between the first-degree relatives of the schizotypal/paranoid personality disorder and the other personality disorder control proband samples. These results suggest a specific familial association between schizophrenia-related disorders, particularly schizophrenia-related personality disorders, and clinically diagnosed schizotypal patients.

Surface-enhanced Raman scattering of dopamine at polymer-coated silver electrodes

Attenuation of dopamine surface-enhanced Raman scattering (SERS) spectra at silver electrodes by protein adsorption is described. Polymer-modified electrodes eliminate protein adsorption effects. Partially hydrolyzed cellulose acetate coatings prevent protein adsorption and allow transport of dopamine to and from the electrode surface. Dopamine SERS spectra from these electrodes are similar to those obtained at uncoated electrodes. Perfluorosulfonate (Nafion) coatings also prevent protein adsorption. However, dopamine transported to the electrode remains trapped inside the coating and cannot be removed.

Restoration of cholinomimetic activity by clonidine in cholinergic plus noradrenergic lesioned rats

The effects of combined lesions of forebrain cholinergic and noradrenergic systems on memory and responsivity to the memory enhancing effects of cholinomimetics were investigated in rats. Forebrain noradrenergic deficits produced by the injection of 6-hydroxydopamine into the ascending noradrenergic bundle (ANB) blocked the ability of cholinomimetics such as physostigmine and oxotremorine to enhance retention test performance in nucleus basalis of Meynert lesioned rats. Low doses of the noradrenergic receptor agonist clonidine, when administered in conjunction with cholinomimetics reversed this blockade. These results suggest that combined cholinergic/noradrenergic therapy may be of value in the treatment of some Alzheimer's disease patients.

Dementia with coexistent major depression

Eleven percent (N = 25) of 232 dementia patients seen in an active geropsychiatry service also met criteria for major depression. Ten patients with dementia/depression were prospectively compared with 10 non-depressed demented and 33 nondemented depressed patients on pretreatment and posttreatment ratings of depression and cognition/memory. Seventy percent (N = 7) of the dementia/depression group and 73% (N = 24) of the depression-only group responded to antidepressant therapy. Signs and symptoms of depression complicating dementia were similar to depressive phenomena in the depression-only group. Depression with dementia appeared to lower performance on cognitive tests. Following treatment, although cognitive impairment remained in the demented range, test performance improved.

Interactions of forebrain cholinergic and somatostatinergic systems in the rat

The neurochemical, behavioral and pharmacological effects of forebrain cholinergic and somatostatinergic deficits were assessed in adult rats. Brain somatostatinergic activity was manipulated by the systemic administration of different doses of cysteamine. Forebrain cholinergic systems were lesioned by the infusion of ibotenic acid into the nucleus basalis of Meynert (nbM). Forebrain cholinergic lesions did not affect forebrain somatostatin-like-immunoreactivity (SLI). Depletion of forebrain SLI by cysteamine did not significantly affect forebrain cholinergic marker activity. The combination of forebrain cholinergic deficits with forebrain somatostatinergic deficits did not lead to any greater impairment of mnemonic function than that produced by lesions alone, nor did SLI deficits hamper the efficacy of physostigmine to enhance memory in sham operated or nbM-lesioned rats. These results suggest that although forebrain cholinergic and somatostatinergic systems do interact at some levels, this interaction is a minor one with respect to neurochemical, behavioral or pharmacological variables.

Toward a therapeutic strategy based on amyloid precursor protein: unanswered questions

Undoubtedly, the future will see experimental therapeutics based on attempts to alter the processing of the amyloid precursor protein, and the formation of senile plaques. As these approaches evolve, it will become increasingly important to determine the role of amyloid precursor protein in normal and abnormal brain. Amyloid precursor protein may have beneficial therapeutic effects that need to be preserved. Any agent designed to alter the process of amyloid precursor protein would be designed to alter the course of Alzheimer's disease. Methodological problems abound in clinical studies designed to show the ability of a therapeutic agent to slow the progress of a degenerative brain disease. These difficulties and possible solutions are explored.

9-Amino-1,2,3,4-tetrahydroacridin-1-ols: synthesis and evaluation as potential Alzheimer's disease therapeutics

The synthesis of a series of 9-amino-1,2,3,4-tetrahydroacridin-1-ols is reported. These compounds are related to 1,2,3,4-tetrahydro-9-acridinamine (THA, tacrine). They inhibit acetylcholinesterase in vitro and are active in a model that may be predictive of activity in Alzheimer's disease--the scopolamine-induced impairment of 24-h memory of a passive dark-avoidance paradigm in mice. Two compounds, (+/-)-9-amino-1,2,3,4-tetrahydroacridin-1-ol maleate (1a, HP-029) and (+/-)-9-(benzylamino)-1,2,3,4-tetrahydroacridin-1-ol maleate (1p, HP-128), were also active in reversing the deficit in 72-h retention of a one-trial dark-avoidance task in rats, induced by ibotenic acid lesions in the nucleus basalis magnocellularis. In addition, compound 1 p showed potent in vitro inhibition of the uptake of radiolabeled noradrenaline and dopamine (IC50 = 0.070 and 0.30 microM, respectively). Compounds 1a and 1p, which showed less acute toxicity in both rats and mice than THA, are in phase II and phase I clinical trials, respectively, for Alzheimer's disease.

Serotonergic studies in patients with affective and personality disorders. Correlates with suicidal and impulsive aggressive behavior

Dysfunction of the central serotonergic system has been variously associated with depression and with suicidal and/or impulsive aggressive behavior. To evaluate central serotonergic function in relation to these variables, prolactin responses to a single-dose challenge with fenfluramine hydrochloride (60 mg orally), a serotonin releasing/uptake-inhibiting agent, were examined in 45 male patients with clearly defined major affective (n = 25) and/or personality disorder (n = 20) and in 18 normal male control patients. Prolactin responses to fenfluramine among all patients were reduced compared with responses of controls. Reduced prolactin responses to fenfluramine were correlated with history of suicide attempt in all patients but with clinician and self-reported ratings of impulsive aggression in patients with personality disorder only; there was no correlation with depression. These results suggest that reduced central serotonergic function is present in a subgroup of patients with major affective and/or personality disorder and is associated with history of suicide attempt in patients with either disorder, but with impulsive aggression in patients with personality disorder only.

Attenuation of nucleus basalis of Meynert lesion-induced cholinergic deficits by nerve growth factor

Nerve growth factor (NGF) was administered into either the lateral ventricle or into the basal forebrain of n. basalis of Meynert (nbM) lesioned rats. Rats received either continuous infusion of 5 micrograms of 7S NGF per day for 28 days, or 5 micrograms of 7S NGF on 4 occasions distributed evenly during the first two post-lesion weeks. The administration of NGF reduced lesion-induced cortical cholinergic marker deficits by approximately 50%, irrespective of the locus or mode of NGF administration. Thus NGF is able to attenuate lesion-induced cholinergic deficits across a range of treatment and lesion conditions.

Cyclic-AMP production by polymorphonuclear leukocytes in psychiatric disorders

The cyclic adenosine monophosphate (cAMP) responses to histamine, prostaglandin-E1, and isoproterenol in polymorphonuclear leukocytes from drug-free normal controls and patients with schizophrenia or major depressive disorder were compared. These three groups of subjects did not differ in their cAMP responses to receptor activation. Exacerbated and remitted patients with either schizophrenia or major depressive disorder did not differ in their cAMP responses. The data indicate that in polymorphonuclear leukocytes, the cAMP responses to activation of histamine H2, prostaglandin-E1, or beta-adrenergic receptors are neither state-independent nor state-dependent markers for schizophrenia or major depressive disorder.

Premorbid sociosexual functioning and long-term outcome in schizophrenia

Chronic schizophrenic patients with the most severe social deterioration have been shown to differ from other chronic schizophrenic patients with respect to measures of left-to-right ventricular asymmetry, negative symptoms, and response to haloperidol treatment. In the current study, the authors investigated the social antecedents of these characteristics of very poor outcome schizophrenia in 69 chronic schizophrenic patients. Poor premorbid sociosexual functioning was associated with more severe left-to-right ventricular asymmetry, greater severity of negative symptoms, fewer positive symptoms, and worse current social functioning. These data suggest that factors associated with severe social deterioration in the end stage of schizophrenia are also associated with premorbid sociosexual impairment.

Eye tracking, schizophrenic symptoms, and schizotypal personality disorder

Schizophrenic patients and patients with schizotypal personality disorder were significantly more likely than normal controls to demonstrate impaired eye tracking performance. Fifteen of 27 schizophrenics and 15 of 27 schizotypals had impaired eye tracking, compared with 11 of 39 normal controls. In the schizophrenic group, including 10 out-patients in a stable state of relative remission, impaired eye tracking was associated with more severe formal thought disorder and more time spent in psychiatric hospitals. Among stable schizophrenic out-patients, poor eye tracking was related to more severe formal thought disorder and greater overall psychopathology. This pattern of results suggests a possible relation between eye tracking impairment and more severe enduring symptoms across the spectrum of schizophrenic and schizophrenia-related disorders.

Age-dependent expression of familial risk in Alzheimer's disease

There is growing evidence for genetic causes of Alzheimer's disease; therefore, consideration of its age at onset among genetically predisposed individuals is timely. The authors studied the onset of Alzheimer-like dementia in families of 79 probands ascertained clinically for the Bronx Veterans Administration/Mt. Sinai School of Medicine longitudinal studies of Alzheimer's disease. Analyses among their 379 first-degree relatives, living and decreased, suggested that 1) early onsets form a distribution that is distinct from that of later onsets, and thus, different causes or mechanisms may operate in early- and late-appearing disease; 2) age at onset varies as a familial characteristic; 3) with present population survival, only one third of the theoretical predisposition to Alzheimer's disease will become manifest during the lifetime of relatives at risk; and 4) a stable annual incidence of 1.5 per cent in the early ninth decade, reported by others, can be explained by the operation of a dominant gene with a population allele frequency of 0.13. The authors conclude that different (possibly genetic) causes of Alzheimer's disease may operate in different families or individuals, although much of its predisposition remains latent during the lifetime of those at risk.

Growth hormone response to edrophonium in patients with Alzheimer's disease and normal control subjects

The authors found that growth hormone (GH) response to edrophonium was no different in 12 Alzheimer's disease patients than in eight healthy elderly subjects. Previously reported differences could be due to differences in gender or baseline GH concentrations between patients and control subjects.

A comparison of plasma homovanillic acid concentrations in schizophrenic patients and normal controls

Plasma homovanillic acid concentrations, a potential index of central dopamine turnover, were examined in normal control subjects and chronic schizophrenic patients over a 12-hour period, including the period of sleep. Plasma homovanillic acid concentrations were lower in schizophrenic patients compared with normal controls at all times; however, within the group of schizophrenics, the more symptomatic patients had higher plasma homovanillic acid concentrations than the less severely ill patients. These data are consistent with a more complex role of dopamine in schizophrenia than was previously conceptualized.

Central serotoninergic stimulation by fenfluramine challenge does not affect plasma thyrotropin-stimulating hormone levels in man

Thyrotropin-stimulating hormone (TSH) and prolactin (PRL) responses to an acute oral challenge of fenfluramine (60 mg), a central serotoninergic (5-hydroxytryptamine) releasing/uptake inhibiting agent, were examined in 8 healthy males in order to assess the role of central serotoninergic stimulation in the release of TSH. Plasma PRL, but not TSH, was significantly elevated by fenfluramine. These data suggest that central serotoninergic activity does not play an important role in the physiologic release of plasma TSH in man. Further, thyrotropin-releasing hormone is unlikely to be the PRL-releasing factor involved in the fenfluramine-induced stimulation of PRL.

4-Aminopyridine in the treatment of Alzheimer's disease

The cognitive and behavioral effect of 4-aminopyridine (4-AP) was examined in Alzheimer's disease (AD) using a dose finding/replication study design. Fourteen inpatients, aged 54-89 years (mean 66.1 +/- 10.6 SD), meeting NINCDS criteria for probable AD, were studied. Three doses of 4-AP--2.5 mg b.i.d., 5 mg b.i.d., and 10 mg b.i.d.--or placebo were administered for 4 consecutive days in random order. Symptomatic assessment was performed on the fourth day of each condition using the Alzheimer Disease Assessment Scale (ADAS). Thereafter, the dose on which the best performance occurred was readministered, as was placebo. Of the 13 patients who completed the dose-finding phase, 7 patients had at least one dose of 4-AP that was associated with less severe symptoms than was placebo, and those patients were included in the replication phase. Results indicated no significant difference in total ADAS scores (p greater than 0.05). Examination of the ADAS subscales revealed no significant 4-AP effect on any particular symptom. Possible explanations of the lack of a drug effect in this study include the unselective release of neurotransmitters by 4-AP, poor penetration into the central nervous system (CNS), and the presenile onset of the disease in these patients.

Endocrine changes in Alzheimer's disease

In conclusion, at present, no consistent endocrine abnormalities can be detected in patients suffering from Alzheimer's disease. However, assessment of neuroendocrine function might help identify subpopulations of patients with particular neurotransmission abnormalities who are likely to benefit from a specific pharmacologic strategy. For example, patients in whom cholinomimetic drugs produce the greatest elevation in plasma cortisol concentration appear to derive the most symptomatic benefit from these drugs.

Purification and characterization of cytochrome P-450-dependent arachidonic acid epoxygenase from human liver

A novel human liver cytochrome P-450 isozyme (P-450-AA), which catalyzes arachidonic acid epoxidation, has been purified to electrophoretic homogeneity from human liver. As judged spectrally, the newly described isozyme is low spin in the oxidized state, with a soret band at 415 nm and an increased maximum at 451 nm in the CO-difference spectrum. Cytochrome P-450-AA appeared homogeneous as judged by the appearance of a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an estimated molecular weight of 53,100. Although cytochrome P-450-AA had a relatively low specific content of 10.8 nmol/mg, it possessed a high activity of arachidonic acid epoxidation. The P-450-AA oxidized arachidonic acid in a reconstituted system into the four regioisomeric epoxyeicosatrienoic acids (EETs) (5, 6-, 8, 9-, 11, 12-, 14, 15-EETs) at a rate of 2,010 pmol/nmol/min, a rate which is 37-fold higher than that observed with the crude microsomal preparation. Moreover, the purified cytochrome P-450-AA catalyzed the de-ethylation of 7-ethoxyresorufin at the rate of 2970 pmol/nmol/min, whereas other cytochrome P-450-dependent reactions were carried out at 23-2,000-fold lower rates and ranged between 0.3-130 pmol/nmol/min. The amino acid composition is different from that of other cytochrome P-450 isozymes. The NH2-terminal sequence of 20-amino acid residues was compared to that of LM2 and PB2-B2, the phenobarbital-induced forms in rabbit and rats, respectively. Comparison was also made with two forms of human cytochrome P-450, HLc and HLd. There were 7/20 identical residues for P-450-AA and LM2 and 4/20 for P-450-AA and PB2-B2. There were 2/20 identical residues for P-450-AA and HLd, and no identical residues were found for HLc. We conclude that the biologically active EETs, are formed by a distinct and unique P-450 isozyme from human liver and that arachidonic acid can serve as a screen for detection of the novel P-450 isozyme.

Familial aggregation in Alzheimer's disease: comparison of risk among relatives of early-and late-onset cases, and among male and female relatives in successive generations

Although the morbid risk of Alzheimer's disease (AD) is increased among relatives of AD index cases, it is not yet clear whether the extent of familial aggregation is similar for probands of all ages, or for male and female relatives. The present study investigated the incidence of AD-like illness among 379 first-degree relatives of 79 probands in a continuing longitudinal study of AD. Cumulative incidence among relatives increased strikingly with age to 49% by age 87, and the risks observed did not differ appreciably among relatives of presenile-onset versus senile-onset probands. Risks were also similar among parents and sibs. Female relatives appeared to develop the disease earlier than males, but the age-specific risk curves for the two sexes did not differ significantly. These results should not be viewed as direct evidence for dominant genetic transmission of late-onset AD, but they suggest a rationale for formal genetic studies in late-onset (often apparently "sporadic") disease as well as earlier-onset ("familial") cases.

Endocrine changes in Alzheimer's disease

In conclusion, at present, no consistent endocrine abnormalities can be detected in patients suffering from Alzheimer's disease. However, assessment of neuroendocrine function might help identify subpopulations of patients with particular neurotransmission abnormalities who are likely to benefit from a specific pharmacologic strategy. For example, patients in whom cholinomimetic drugs produce the greatest elevation in plasma cortisol concentration appear to derive the most symptomatic benefit from these drugs.

Memory impairment in schizophrenic patients with tardive dyskinesia

Memory functioning was contrasted in 40 schizophrenic patients with and without tardive dyskinesia (TD). Visual and verbal memory tests were used to investigate specific types of impairments. The presence of TD was ascertained using the Abnormal Involuntary Movement Scale (AIMS). TD patients scored significantly lower than non-TD patients on two measures of visual learning, though no differences were found for verbal learning or immediate recall. These results are consistent with previous reports that schizophrenic patients with TD demonstrate impaired cognitive functioning. They also raise the possibility that the neurochemical and structural changes underlying TD may produce specific deficits in memory for visual materials. In addition, a significant relationship was found between total score on the Brief Psychiatric Rating Scale (BPRS) and performance on all of the test measures included in the cognitive test battery. This demonstrates the importance of attending to the overall level of schizophrenic symptomatology when evaluating results from experimental learning tasks.

Platelet alpha 2-adrenergic receptor function in psychiatric disorders

The inhibitory effects of norepinephrine (NE) on the cyclic adenosine-3',5'-monophosphate (cAMP) response to prostaglandin E1 (PGE1), a measure of alpha 2-adrenergic receptor function, have been compared in platelets from drug-free schizophrenic patients, depressive patients, and normal controls. The absolute value of the inhibition by NE of the cAMP response to PGE1 was smaller in platelets from schizophrenic and depressive patients than in controls. However, this result was secondary to the smaller baseline platelet cAMP response to PGE1 in patients with these disorders. Effects of NE on cAMP production did not discriminate between actively ill and remitted patients with either schizophrenia or depression. Platelet alpha 2-receptor sensitivity, as measured by the effects of NE on cAMP production, does not appear to be altered in these psychiatric disorders.

Effects of debrisoquin and haloperidol on plasma homovanillic acid concentration in schizophrenic patients

Plasma levels of the dopamine metabolite homovanillic acid (pHVA) may potentially reflect upon central dopamine activity. This study examines the effects of debrisoquin, haloperidol, and the two drugs combined on pHVA concentrations of schizophrenic patients. Debrisoquin is a drug that suppresses the peripheral formation of homovanillic acid without affecting the central formation. Acute haloperidol administration consistently increased pHVA concentrations in patients pretreated or not pretreated with debrisoquin, suggesting that this increment reflects haloperidol's central and not peripheral effects.