The Expert Consensus Guideline Series: Medication Treatment of Bipolar Disorder 2000

OBJECTIVES

New treatments for bipolar disorder have been reported since we first published survey-based expert consensus guidelines in 1996. The evidence for these treatments varies widely; data are especially limited regarding comparisons between treatments and how to sequence them. We therefore undertook a new survey of expert opinion in order to bridge gaps between the research evidence and key clinical decisions.

METHOD

Based on a literature review, a written survey was prepared which asked about 1,276 options for psychopharmacologic interventions in 48 specific clinical situations. Most options were scored using a modified version of the RAND Corporation 9-point scale for rating appropriateness of medical decisions. We contacted 65 national experts, 58 of whom (89%) completed the survey. Consensus on each option was defined as a non-random distribution of scores by chi-square test. We assigned a categorical rank (first-line/preferred choice, second-line/alternate choice, third-line/usually inappropriate) to each option based on the confidence interval of its mean rating. Guideline tables indicating preferred treatment strategies were then developed for key clinical situations.

RESULTS

The expert panel reached consensus on many key strategies, including acute and preventive treatment for mania (euphoric, mixed, and dysphoric subtypes), depression, and rapid cycling, and approaches to managing the complications of treatment resistance and comorbidity. Use of a mood stabilizer is recommended in all phases of treatment. Divalproex (especially for mixed or dysphoric subtypes) and lithium are the cornerstone choices among this class for both acute and preventive treatment of mania. Regardless of which is selected first, if monotherapy fails, the next recommended intervention is to use these agents in combination. The combination can then serve as the foundation on which other medications are added, if needed. Carbamazepine is the leading alternative mood stabilizer for mania. Expert opinion regards other new anticonvulsants as second-line options (e.g., if the previously mentioned mood stabilizers fail or are contraindicated). For milder depression, a mood stabilizer, especially lithium, may be used as monotherapy. Divalproex and lamotrigine are other first-line choices. For more severe depression, a standard antidepressant should be combined with lithium or divalproex. Bupropion, selective serotonin reuptake inhibitors (SSRIs), and venlafaxine are preferred antidepressants, and should be tapered 2 to 6 months after remission. Divalproex monotherapy is recommended for initial treatment of either depression or mania with rapid cycling. Antipsychotics are recommended for use with the above regimens for mania or depression with psychosis, and as potential adjuncts in non-psychotic episodes. Atypical antipsychotics, especially olanzapine and risperidone, were generally preferred over conventional antipsychotics. Recommendations are also given concerning the use of electroconvulsive therapy (ECT), clozapine, thyroid hormone, stimulants, and various novel agents for patients with treatment-refractory illness.

CONCLUSIONS

The experts reached high levels of consensus on key steps in treating bipolar disorder despite obvious gaps in high-quality data. To evaluate many of the treatment options in this survey, the experts had to extrapolate beyond controlled data; however, their recommendations are generally conservative. Experts reserve strongest support for initial strategies and individual medications for which there are high-quality research data, or for which there are longstanding patterns of clinical usage. Within the limits of expert opinion and with the understanding that new research data may take precedence, these guidelines provide clear pathways for addressing common clinical questions in a manner that can be used to inform clinicians and educate patients regarding the relative merits of a variety of interventions.

Acid resistance of Helicobacter pylori depends on the UreI membrane protein and an inner membrane proton barrier

ureI encodes an inner membrane protein of Helicobacter pylori. The role of the bacterial inner membrane and UreI in acid protection and regulation of cytoplasmic urease activity in the gastric microorganism was studied. The irreversible inhibition of urease when the organism was exposed to a protonophore (3,3',4', 5-tetrachlorsalicylanide; TCS) at acidic pH showed that the inner membrane protected urease from acid. Isogenic ureI knockout mutants of several H. pylori strains were constructed by replacing the ureI gene of the urease gene cluster with a promoterless kanamycin resistance marker gene (kanR). Mutants carrying the modified ureAB-kanR-EFGH operon all showed wild-type levels of urease activity at neutral pH in vitro. The mutants resisted media of pH > 4.0 but not of pH < 4.0. Whereas wild-type bacteria showed high levels of urease activity below pH 4.0, this ability was not retained in the ureI mutants, resulting in inhibition of metabolism and cell death. Gene complementation experiments with plasmid-derived H. pylori ureI restored wild-type properties. The activation of urease activity found in structurally intact but permeabilized bacteria treated with 0.01% detergent (polyoxy-ethylene-8-laurylether; C12E8), suggested a membrane-limited access of urea to internal urease at neutral pH. Measurement of 14C-urea uptake into Xenopus oocytes injected with ureI cRNA showed acid activation of uptake only in injected oocytes. Acceleration of urea uptake by UreI therefore mediates the increase of intracellular urease activity seen under acidic conditions. This increase of urea permeability is essential for H. pylori survival in environments below pH 4.0. ureI-independent urease activity may be sufficient for maintenance of bacterial viability above pH 4.0.

What is to be done? Controversies in the diagnosis and treatment of manic-depressive illness

BACKGROUND

In recent years, much progress has been made in the diagnosis and treatment of schizophrenia and depression. Bipolar disorder, however, remains frequently misunderstood, leading to inconsistent diagnosis and treatment. Why is the case? What is to be done about it?

METHODS

We critically review studies in the nosology of bipolar disorder and the effects of antidepressant agents.

RESULTS

Bipolar disorder is underdiagnosed and frequently misdiagnosed as unipolar major depressive disorder. Antidepressants are probably overused and mood stabilisers underused. Reasons for underdiagnosis include patients' impaired insight into mania, failure to involve family members in the diagnostic process, and inadequate understanding by clinicians of manic symptoms. We propose using a mnemonic to aid in diagnosis, obtaining family report, and utilising careful clinical interviewing techniques given the limitations of patients' self-report. We recommend aggressive use of mood stabilisers, and less emphasis on antidepressants.

CONCLUSIONS

The state of diagnosis and treatment in bipolar disorder is suboptimal. More diagnostic attention to manic criteria is necessary and the current pattern of use of antidepressant use in bipolar disorder needs to change.

Effects of mutations in M4 of the gastric H+,K+-ATPase on inhibition kinetics of SCH28080

The effects of site-directed mutagenesis were used to explore the role of residues in M4 on the apparent Ki of a selective, K+-competitive inhibitor of the gastric H+,K+ ATPase, SCH28080. A double transfection expression system is described, utilizing HEK293 cells and separate plasmids encoding the alpha and beta subunits of the H+,K+-ATPase. The wild-type enzyme gave specific activity (micromoles of Pi per hour per milligram of expressed H+,K+-ATPase protein), apparent Km for ammonium (a K+ surrogate), and apparent Ki for SCH28080 equal to the H+, K+-ATPase purified from hog gastric mucosa. Amino acids in the M4 transmembrane segment of the alpha subunit were selected from, and substituted with, the nonconserved residues in M4 of the Na+, K+-ATPase, which is insensitive to SCH28080. Most of the mutations produced competent enzyme with similar Km,app values for NH4+ and Ki,app for SCH28080. SCH28080 affinity was decreased 2-fold in M330V and 9-fold in both M334I and V337I without significant effect on Km,app. Hence methionine 334 and valine 337 participate in binding but are not part of the NH4+ site. Methionine 330 may be at the periphery of the inhibitor site, which must have minimum dimensions of approximately 16 x 8 x 5 A and be accessible from the lumen in the E2-P conformation. Multiple sequence alignments place the membrane surface near arginine 328, suggesting that the side chains of methionine 334 and valine 337, on one side of the M4 helix, project into a binding cavity within the membrane domain.

Comorbidity of attention deficit hyperactivity disorder with early- and late-onset bipolar disorder

OBJECTIVE

The relationship between attention deficit hyperactivity disorder (ADHD) and earlier age at onset of affective illness was examined in probands with a history of bipolar disorder.

METHOD

The authors assessed 56 adult bipolar subjects. Those with a history of childhood ADHD (N=8) were age and sex matched with bipolar subjects without a history of childhood ADHD (N=8).

RESULTS

The age at onset of the first affective episode was lower for the subjects with bipolar disorder and a history of childhood ADHD (mean=12.1 years, SD=4.6) than for those without a history of childhood ADHD (mean=20. 0 years, SD=11.3).

CONCLUSIONS

ADHD in children of bipolar probands might identify children at highest risk for development of bipolar disorder.

Comparison of covalent with reversible inhibitor binding sites of the gastric H,K-ATPase by site-directed mutagenesis

The gastric H,K-ATPase is covalently inhibited by substituted pyridyl-methylsulfinyl-benzimidazoles, such as omeprazole, that convert to thiophilic probes of luminally accessible cysteines in the acid space. The K(+) competitive inhibitor, SCH28080, prevented inhibition of acid transport by omeprazole. In stably expressing HEK293 cells, the benzimidazole-reactive cysteines, Cys-321 (transmembrane helix (TM) 3), Cys-813 and Cys-822 (TM5/6), and Cys-892 (TM7/8) were mutated to the amino acids found in the SCH28080-resistant Na,K-ATPase and kinetic parameters of H,K-ATPase activity analyzed. Mutations of Cys-822 and Cys-892 had insignificant effects on the K(i(app)), K(m(app)) or V(max), but mutations of Cys-813 to threonine and Cys-321 to alanine decreased the affinity for SCH28080. Mutation of Cys-321 to alanine produced mixed kinetics of inhibition, still with higher affinity for the cation-free form of phosphoenzyme. Since the phenylmethoxy ring of the imidazo-pyridine inhibitors binds to TM1/2, as shown by earlier photoaffinity studies, and the mutations in TM6 (Cys-813 --> Thr) as well as the end of TM3 (Cys-321 --> Ala) decrease the affinity for SCH28080, the TM1/2, TM3, and TM6 helices lie within approximately 16 A of each other based on the size of the active, extended conformation of SCH28080.

Expression of the Helicobacter pylori ureI gene is required for acidic pH activation of cytoplasmic urease

ureI encodes an integral cytoplasmic membrane protein. It is present in the urease gene cluster of Helicobacter pylori and is essential for infection and acid survival, but its role is unknown. To determine the function of UreI protein, we produced H. pylori ureI deletion mutants and measured the pH dependence of urease activity of intact and lysed bacteria and the effect of urea on the membrane potential. We also determined ureI expression, urease activity, and the effect of urea on membrane potential of several gastric and nongastric Helicobacter species. ureI was found to be present in the genome of the gastric Helicobacter species and absent in the nongastric Helicobacter species studied, as determined by PCR. Likewise, Western blot analysis confirmed that UreI was expressed only in the gastric Helicobacter species. When UreI is present, acidic medium pH activation of cytoplasmic urease is found, and urea addition increases membrane potential at acidic pH. The addition of a low concentration of detergent raised urease activity of intact bacteria at neutral pH to that of their homogenates, showing that urease activity was membrane limited. No acidic pH activation or urea induced membrane potential changes were found in the nongastric Helicobacter species. The ureI gene product is probably a pH activated urea transporter or perhaps regulates such a transporter as a function of periplasmic pH.

A novel lens epithelium gene, LEP503, is highly conserved in different vertebrate species and is developmentally regulated in postnatal rat lens

The development of the lens is dependent on the proliferation of lens epithelial cells and their differentiation into fiber cells near the lens bow/equator. Identification of genes specifically expressed in the lens epithelial cells and their functions may provide insight into molecular events that regulate the processes of lens epithelial cell differentiation. In this study, a novel lens epithelium gene product, LEP503, identified from rat by a subtractive cDNA cloning strategy was investigated in the genome organization, mRNA expression and protein localization. The genomic sequences for LEP503 isolated from rat, mouse and human span 1754 bp, 1694 bp and 1895 bp regions encompassing the 5'-flanking region, two exons, one intron and 3'-flanking region. All exon-intron junction sequences conform to the GT/AG rule. Both mouse and human LEP503 genes show very high identity (93% for mouse and 79% for human) to rat LEP503 gene in the exon 1 that contains an open reading frame coding for a protein of 61 amino acid residues with a leucine-rich domain. The deduced protein sequences also show high identity (91% between mouse and rat and 77% between human and rat). Western blot shows that LEP503 is present as a specific approximately 6.9 kDa band in the water-insoluble-urea-soluble fraction of lens cortex where lens epithelium is included. Immuno-staining shows that LEP503 is localized in the epithelial cells along the entire anterior surface of rat lens. Developmentally, LEP503 is expressed at a low level at newborn, and then the expression level increases by about ten-fold around postnatal day 14 and remains at this high level for about 25 days before it drops back to the low level by postnatal day 84. These data suggest that the LEP503 may be an important lens epithelial cell gene involving the processes of epithelial cell differentiation.

A H+-gated urea channel: the link between Helicobacter pylori urease and gastric colonization

Acidic media trigger cytoplasmic urease activity of the unique human gastric pathogen Helicobacter pylori. Deletion of ureI prevents this activation of cytoplasmic urease that is essential for bacterial acid resistance. UreI is an inner membrane protein with six transmembrane segments as shown by in vitro transcription/translation and membrane separation. Expression of UreI in Xenopus oocytes results in acid-stimulated urea uptake, with a pH profile similar to activation of cytoplasmic urease. Mutation of periplasmic histidine 123 abolishes stimulation. UreI-mediated transport is urea specific, passive, nonsaturable, nonelectrogenic, and temperature independent. UreI functions as a H+-gated urea channel regulating cytoplasmic urease that is essential for gastric survival and colonization.

Role of neuropeptide-sensitive L-type Ca(2+) channels in histamine release in gastric enterochromaffin-like cells

Peptides release histamine from enterochromaffin-like (ECL) cells because of elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)) by either receptor-operated or voltage-dependent Ca(2+) channels (VDCC). To determine whether VDCCs contribute to histamine release stimulated by gastrin or pituitary adenylate cyclase-activating polypeptide (PACAP), the presence of VDCCs and their possible modulation by peptides was investigated in a 48-h cultured rat gastric cell population containing 85% ECL cells. Video imaging of fura 2-loaded cells was used to measure [Ca(2+)](i), and histamine was assayed by RIA. Cells were depolarized by increasing extracellular K(+) concentrations or by 20 mM tetraethylammonium (TEA(+)). Cell depolarization increased transient and steady-state [Ca(2+)](i) and resulted in histamine release, dependent on extracellular Ca(2+). These K(+)- or TEA(+)-dependent effects on histamine release from ECL cells were coupled to activation of parietal cells in intact rabbit gastric glands, and L-type channel blockade by 2 microM nifedipine inhibited 50% of [Ca(2+)](i) elevation and histamine release. N-type channel blockade by 1 microM omega-conotoxin GVIA inhibited 25% of [Ca(2+)](i) elevation and 14% of histamine release. Inhibition was additive. The effects of 20 mM TEA(+) were fully inhibited by 2 microM nifedipine. Both classes of Ca(2+) channels were found in ECL cells, but not in parietal cells, by RT-PCR. Nifedipine reduced PACAP-induced (but not gastrin-stimulated) Ca(2+) entry and histamine release by 40%. Somatostatin, peptide YY (PYY), and galanin dose dependently inhibited L-type Ca(2+) channels via a pertussis toxin-sensitive pathway. L-type VDCCs play a role in PACAP but not gastrin stimulation of histamine release from ECL cells, and the channel opening is inhibited by somatostatin, PYY, and galanin by interaction with a G(i) or G(o) protein.

Analysis of the membrane domain of the gastric H(+)/K(+)-ATPase

A structure of the catalytic or alpha subunit of the H(+)/K(+)-ATPase, with ten transmembrane segments, and of the beta subunit, with a single such segment, was established using a combination of tryptic cleavage and peptide sequencing and in vitro translation. Sites at which covalent ligands bind to external surfaces were also defined by cleavage, separation and sequencing. Cys813 was found to be the common covalent binding site for all the substituted pyridyl methylsulfinyl benzimidazoles. The binding region of a K(+)-competitive reagent, the 1,2 α -imidazo-pyridine SCH 28080, was defined by the kinetic effects of site-specific mutations. Amino acids substitutions in membrane-spanning segments M1, M3, M4 and M6 were found to influence the apparent inhibitor constant, K(i), to varying degrees, some having a large effect, some a moderate effect and some a slight effect, whereas some mutations had no effect. We interpret changes in K(i) without effects on the apparent Michaelis constant, K(m), as affecting SCH 28080 binding only. Mutation of Cys813 significantly affected the K(i) for SCH 28080, explaining the prevention of benzimidazole inhibition by the imidazo-pyridine.A model of the α subunit was constructed with a vestibule on the luminal surface of the pump bounded by M1-M6 and containing the SCH 28080 binding region. The cation binding site is suggested to be more towards the cytoplasmic face of the enzyme's membrane domain. This model predicts the membrane peptide associations for the catalytic subunit. Biochemical and yeast two-hybrid methods place the beta subunit in association with M8, whereas similar methods place M5/6 in proximity to M9/10. These results, when combined with analysis of the two-dimensional crystals of the sarcoplasmic reticular Ca(2+) and Neurospora crassa H(+)-ATPases, provide the basis for a tentative model of the arrangement of the six core segments of the gastric H(+)/K(+)-ATPase.

Ovarian function before and after salpingectomy in artificial reproductive technology patients

To determine the effect of the removal of the tube on ovarian function we studied 52 artificial reproduction technology cycles in 26 women before and after undergoing laparoscopic salpingectomy for ectopic pregnancy. Ovarian response was measured by the duration and quantity of human menopausal gonadotrophins used in the cycle, the pre-ovulatory concentrations of oestradiol, the number of oocytes retrieved, and the quality of the embryos. All parameters were compared between cycles carried out before and after salpingectomy as well as between affected and unaffected sides. Our findings show no significant difference in any of the parameters studied. We conclude that laparoscopic salpingectomy does not abate ovarian response in artificial reproduction technology cycles that follow the procedure.

Weight gain associated with use of psychotropic medications

Weight gain is associated with the use of many psychotropic medications, including lithium, valproic acid, and several conventional and newer antipsychotics. Patients asked to select from among several comparable drugs often choose the one least likely to cause weight gain, even if the drug is less effective or has other troublesome adverse effects. For many patients, weight gain is so intolerable that they discontinue treatment. Patients who continue treatment are at risk for clinically significant weight gain that can progress to obesity. Even after patients stop taking the drug, weight gained during therapy may be difficult to lose. Thus, the best approach is to attempt to prevent weight gain when feasible, possibly through pretreatment dietary counseling and judicious drug selection, and to intervene as soon as weight gain becomes evident.

PACAP type I receptor activation regulates ECL cells and gastric acid secretion

Pituitary adenylate cyclase activating polypeptide (PACAP) is present in gastric nerves, and PACAP receptors (PAC1) are found on gastric enterochromaffin-like (ECL) cells. Expression of PAC1 splice variants in purified ECL cells was determined by RT-PCR. PACAP effects on ECL cells were analyzed by video imaging of [Ca(2+)](i) and histamine release; its effects on gastric glands were examined by confocal microscopy of [Ca(2+)](i) in ECL and parietal cells. PACAP action on D cells was measured by [Ca(2+)](i) and radioimmunoassay. PACAP effects on acid secretion were determined in fistula rats with or without neutralizing anti-somatostatin antibodies. All splice variants of PAC1 were found, but vasoactive intestinal polypeptide (VIP) receptor (VPAC) products were absent. PACAP-27 and -38 dose-dependently raise [Ca(2+)](i) in ECL cells, and stimulated histamine release. VIP had a much lower affinity, which demonstrates the presence of PAC1 but not VPAC. PACAP elevated [Ca(2+)](i) in ECL and parietal cells of superfused gastric glands, but only the parietal cell signal was inhibited by ranitidine, showing the absence of PAC1 on parietal cells, and demonstrating functional coupling between the cell types. PACAP and VIP stimulated calcium signaling and somatostatin release from D cells with almost equal efficacy. Acid secretion was stimulated after intravenous injection of PACAP into rats treated with somatostatin antibody. PACAP is a candidate as a mediator of neural regulation of acid secretion.

Five-factor personality traits in patients with seasonal depression: treatment effects and comparisons with bipolar patients

BACKGROUND

Increasingly, the Five Factor Model (FFM) of personality is being used to assess personality characteristics of patients with Axis I disorders. Recent study indicates that patients with the seasonal subtype of major depression (SAD) may differ meaningfully from other depressed patients. In the present study, we further examined this finding, with attention to the stability of personality characteristics across treatment.

METHODS

We used the NEO-FFM to assess the personality characteristics of two samples of depressed outpatients: patients with SAD and patients with bipolar disorder. Assessment was repeated in the SAD patients after light therapy.

RESULTS

Consistent with previous research, we found elevated scores on the Openness domain in the SAD patients. SAD patients also scored significantly lower on Neuroticism and significantly higher on the Conscientiousness and Extroversion domains than patients with bipolar disorder. Scores on the Openness domain remained elevated after treatment of SAD; this occurred in the context of significant decreases in Neuroticism and increases in Extroversion scores.

LIMITATIONS

These results were obtained in a relatively small-sample study. Although our sample of bipolar patients were taking mood stabilizers, it is unlikely that medication effects could explain our results.

CONCLUSIONS

Our findings are consistent with those reported by Bagby et al. (Major depression and the five-factor model of personality. J. Pers. Disord. 1995;9:224-234) and suggests that Neuroticism and Extroversion are the FFM domains most responsive to treatment for depression. Our results also suggest that elevations on the Openness domain do not change with treatment and may be an enduring characteristic of patients with SAD.

Membrane insertion scanning of the human ileal sodium/bile acid co-transporter

Mammalian sodium-dependent bile acid transporters (SBATs) responsible for bile salt uptake across the liver sinusoidal or ileal/renal brush border membrane have been identified and share approximately 35% amino acid sequence identity. Programs for prediction of topology and localization of transmembrane helices identify eight or nine hydrophobic regions for the SBAT sequences as membrane spanning. Analysis of N-linked glycosylation has provided evidence for an exoplasmic N-terminus and a cytoplasmic C-terminus, indicative of an odd number of transmembrane segments. To determine the membrane topography of the human ileal SBAT (HISBAT), an in vitro translation/translocation protocol was employed using three different fusion protein constructs. Individual HISBAT segments were analyzed for signal anchor or stop translocation (stop transfer) activity by insertion between a cytoplasmic anchor (HK M0) or a signal anchor segment (HK M1) and a glycosylation flag (HK beta). To examine consecutive HISBAT sequences, sequential hydrophobic sequences were inserted into the HK M0 vector or fusion vectors were made that included the glycosylated N-terminus of HISBAT, sequential hydrophobic sequences, and the glycosylation flag. Individual signal anchor (SA) and stop transfer (ST) properties were found for seven out of the nine predicted hydrophobic segments (H1, H2, H4, H5, H6, H7, and H9), supporting a seven transmembrane segment model. However, the H3 region was membrane inserted when translated in the context of the native HISBAT flanking sequences. Furthermore, results from translations of sequential constructs ending after H7 provided support for integration of H8. These data provide support for a SBAT transmembrane domain model with nine integrated segments with an exoplasmic N-terminus and a cytoplasmic C-terminus consistent with a recent predictive analysis of this transporter topology.

Lipocortin V may function as a signaling protein for vascular endothelial growth factor receptor-2/Flk-1

Binding of vascular endothelial growth factor (VEGF) to its receptor, VEGFR-2 (Flk-1/KDR), induces dimerization and activation of the tyrosine kinase domain of the receptor, resulting in autophosphorylation of cytoplasmic tyrosine residues used as docking sites for signaling proteins that relay the signals for cell proliferation, migration, and permeability enhancement. We explored the VEGF/receptor signaling pathway by performing a two-hybrid screen of a rat lung cDNA library in yeast using the intracellular domain of rat VEGFR-2 as bait. Two clones encoding lipocortin V were isolated. Subsequent studies with the yeast two-hybrid assay showed that the complete intracellular domain of VEGFR-2 was required for the interaction. Co-immunoprecipitation of translated proteins confirmed the interaction between the VEGF receptor and lipocortin V. VEGF induced a rapid tyrosine phosphorylation of lipocortin V in human umbilical vein endothelial cells (HUVEC). Pretreatment of HUVEC with antisense oligodeoxyribonucleotide (ODN) for lipocortin V significantly inhibited VEGF-induced cell proliferation, which was accompanied by a decrease in protein synthesis and tyrosine phosphorylation of lipocortin V. Our results indicate that lipocortin V may function as a signaling protein for VEGFR-2 by directly interacting with the intracellular domain of the receptor and appears to be involved in regulation of vascular endothelial cell proliferation mediated by VEGFR-2.

Stabilization of the H,K-ATPase M5M6 membrane hairpin by K+ ions. Mechanistic significance for p2-type atpases

The integral membrane protein, the gastric H,K-ATPase, is an alpha-beta heterodimer, with 10 putative transmembrane segments in the alpha-subunit and one such segment in the beta-subunit. All transmembrane segments remain within the membrane domain following trypsinization of the intact gastric H,K-ATPase in the presence of K+ ions, identified as M1M2, M3M4, M5M6, and M7, M8, M9, and M10. Removal of K+ ions from this digested preparation results in the selective loss of the M5M6 hairpin from the membrane. The release of the M5M6 fragment is directed to the extracellular phase as evidenced by the accumulation of the released M5M6 hairpin inside the sealed inside out vesicles. The stabilization of the M5M6 hairpin in the membrane phase by the transported cation as well as loss to the aqueous phase in the absence of the transported cation has been previously observed for another P2-type ATPase, the Na, K-ATPase (Lutsenko, S., Anderko, R., and Kaplan, J. H. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 7936-7940). Thus, the effects of the counter-transported cation on retention of the M5M6 segment in the membrane as compared with the other membrane pairs may be a general feature of P2-ATPase ion pumps, reflecting a flexibility of this region that relates to the mechanism of transport.

Donepezil in treatment-resistant bipolar disorder

BACKGROUND

A considerable percentage of patients with bipolar disorder do not respond or do not tolerate conventional treatment. Cholinesterase (ChE) inhibitors have been suggested to possess depressogenic and antimanic properties.

METHODS

We report a case series of treatment-resistant bipolar patients (n = 11) to whom we administered the ChE inhibitor donepezil. Four patients met criteria for current manic episode, 5 for mixed episode, 1 for hypomanic episode, and 1 for major depressive episode. Donepezil was added to current medication on an openlabel basis. Ratings were based on a retrospective chart review.

RESULTS

Of the 11 patients, 6 (54.5%) demonstrated marked improvement (improvement in CGI-S > or = 2), 3 (27.2%) demonstrated slight improvement, 1 did not respond, and 1 did not tolerate the medication. Among those patients who had marked improvement (i.e., responders, n = 6), improvement was observed within 2 weeks or less in 5 of them (83%). Patients experienced only minor side effects.

CONCLUSIONS

These pilot data suggest the efficacy and safety of donepezil in the treatment of bipolar disorder. To our knowledge this is the first published report on the use of donepezil in the treatment of mood disorders. Controlled, randomized, double-blind studies are necessary to validate these preliminary observations.

beta-subunit assembly is essential for the correct packing and the stable membrane insertion of the H,K-ATPase alpha-subunit

The alpha-subunits of H,K-ATPase (HKAalpha) and Na,K-ATPase require a beta-subunit for maturation. We investigated the role of the beta-subunit in the membrane insertion and stability of the HKAalpha expressed in Xenopus oocytes. Individual membrane segments M1, M2, M3, M4, and M9 linked to a glycosylation reporter act as signal anchor (SA) motifs, and M10 acts as a partial stop transfer motif. In combined HKAalpha constructs, M2 acts as an efficient stop transfer sequence, and M3 acts as a SA sequence. However, M5 and M9 have only partial SA function, and M7 has no SA function. Consistent with the membrane insertion properties of segments in combined alpha constructs, M1-3 alpha-proteins are resistant to cellular degradation, and M1-5 up to M1-10 alpha-proteins are not resistant to cellular degradation. However, co-expression with beta-subunits increases the membrane insertion of M9 in a M1-9 alpha-protein and completely protects M1-10 alpha-proteins against cellular degradation. Our results indicate that HKAalpha N-terminal (M1-M4) membrane insertion and stabilization are mediated by intrinsic molecular characteristics; however, the C-terminal (M5-M10) membrane insertion and thus the stabilization of the entire alpha-subunit depend on intramolecular and intermolecular beta-subunit interactions that are similar but not identical to data obtained for the Na,K-ATPase alpha-subunit.