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Biomedical subjects

John M Davis

Publications and source records attributed to John M Davis.

At least 19 recordsLinked to original sources
PubMed2026

Transcranial Alternating Current Stimulation at 40 Hz Improves Social Functioning in Children With Autism Spectrum Disorder: A Randomized Clinical Trial.

BACKGROUND: Autism spectrum disorder (ASD) lacks rapid and effective interventions for its core social difficulties. The right temporoparietal junction (rTPJ), a critical hub for social cognition, together with gamma band abnormalities implicated in ASD, provides a promising neuromodulation target. METHODS: In this randomized, double-blind, sham-controlled trial, 47 children with ASD (39 male; mean [SD] age = 8.79 [2.71] years) were assigned to receive either 21 sessions of 40-Hz high-definition transcranial alternating current stimulation (tACS) targeting the rTPJ (3 sessions/day for 7 days) or sham stimulation, with assessments conducted at baseline, postintervention (week 1), and a 3-week follow-up (week 4). The primary outcome was change in Ohio State University Autism Rating Scale-DSM-5 (OARS-5) total scores. Secondary outcomes included the Aberrant Behavior Checklist-Second Edition, Social Responsiveness Scale-Second Edition, and Short Sensory Profile. Eye-tracking metrics during Frith-Happ&#xe9; animations were exploratory measures of theory of mind (ToM)-related social cognitive processing. RESULTS: The active group demonstrated significant improvements in OARS-5 total scores at week 1 (mean difference = -1.13, 95% CI [-1.78 to -0.47], p < .001) and week 4 (mean difference = -1.47, 95% CI [-2.20 to -0.74], p < .001). Improvements in selected behavioral and sensory domains were observed. Average fixation duration during ToM animations showed a significant group &#xd7; time interaction. No serious adverse events occurred. CONCLUSIONS: These findings suggest that 40-Hz tACS targeting the rTPJ may be associated with rapid improvements in ASD symptom severity, particularly social functioning, in children with ASD, while being well tolerated. Clinical significance requires further evaluation.

Humans↗
PubMed2025

Quantifying and improving rheumatoid arthritis algorithm performance in biobank settings.

OBJECTIVE: To quantify and improve the performance of standard rheumatoid arthritis (RA) algorithms in a biobank setting. METHODS: This retrospective cohort study within the Mayo Clinic (MC) Biobank and MC Tapestry Study identified RA cases by presence of at least two RA codes OR positive anti-cyclic citrullinated peptide antibodies (CCP) plus disease-modifying anti-rheumatic drug (DMARD) prescription as of 7/18/2022. Rheumatology physicians manually verified all RA cases using RA criteria and/or rheumatology physician diagnosis plus DMARD use. All other biobank participants served as non-RA controls. We defined seropositivity as rheumatoid factor and/or anti-CCP positivity. We assessed rules-based and Electronic Medical Records and Genomics (eMERGE) RA algorithms using positive predictive value (PPV). Finally, we developed a novel RA algorithm using a LASSO-based machine learning approach with five-fold cross validation. RESULTS: We identified 1,316 confirmed RA cases (968 MC Biobank, 348 Tapestry, 70 % seropositive) and 82,123 non-RA controls (mean age 65, 61 % female). The PPV of 3 RA codes was 43 %, codes plus DMARD was 54 %, and codes plus DMARD plus seropositivity was 85 %. The PPV of eMERGE was 77 %. Available in the MC Biobank, self-reported RA (PPV 10 %) only minimally improved algorithm performance (PPV from 83 % to 85 %), whereas family history of RA (PPV 3 %) worsened performance. At 90 % PPV, the novel RA algorithm incorporating key variables such as anti-CCP and DMARD use increased sensitivity by 4-11 % compared to eMERGE. CONCLUSION: Rules-based and eMERGE RA algorithms had worse performance in biobank than administrative settings. Our novel RA algorithm outperformed these standard algorithms.

Humans↗
PubMed2006

Is the superior efficacy of new generation antipsychotics an artifact of LOCF?

It has been argued that the efficacy superiority found in meta-analyses for some of the atypical antipsychotics is an artifact of higher dropout rates due to side effects in the haloperidol group combined with last-observation-carried-forward (LOCF) analyses. We therefore reanalyzed a number of pivotal studies comparing new generation antipsychotics (NGAs) and conventional antipsychotics (CAs). A total of 5 studies (n = 1271) comparing amisulpride and 3 studies (n = 2454) comparing olanzapine with CAs were reanalyzed using original patient data. We applied 4 different models: LOCF, completer analysis, LOCF but excluding dropouts due to adverse events, and LOCF but excluding all dropouts with the exception of dropouts related to efficacy. Effect sizes expressed as standardized mean differences between NGAs and CAs based on the 4 different analysis models were compared. The overall results were not different irrespective of the model used. Single studies, however, showed higher effect sizes when LOCF instead of other models was used. Overall, it does not seem that higher dropout rates due to side effects in the haloperidol groups together with LOCF analyses consistently biased the results in favor of amisulpride and olanzapine. Because the results of the single studies, however, showed that this may occasionally be the case, future studies should look at the data from different angles applying sensitivity analyses, and they may use alternative statistics such as mixed models, which need to be developed further. Ultimately, strategies to reduce dropout rates are needed.

Amisulpride↗
PubMed2006

Wound and insect herbivory responsive genes in poplar.

Insect herbivory leads to induced resistance to subsequent infestations in plants. This is due in part to feeding-induced expression of genes that can lead to reduced palatability and/or digestibility of the plant material. We identified 57 distinct differentially expressed genes from poplars that were either infested by gypsy moth (Lymantria dispar) or mechanically wounded. Eleven highly insect-inducible genes were also found to be wound-inducible. Time course analysis revealed diverse timing of peak transcript accumulation. Sequence analysis of promoters suggested that the wound responsive elements, W and DRE, and the jasmonic acid responsive H motif, are over-represented in wound-induced poplar promoters and should be investigated further.

Animals↗
PubMed2006

Reelin down-regulation in mice and psychosis endophenotypes.

Reelin, a large glycoprotein secreted by telencephalic GABAergic neurons, plays an important role in neuronal guidance embryonically and in synaptic plasticity postnatally. The reeler heterozygous mouse (+/rl) appears superficially normal but has been of interest as an animal model for psychosis since the discovery that reelin is 50% down-regulated in postmortem psychotic brain. Brain abnormalities in +/rl are similar to psychotic brain and include a reduction in glutamic acid de carboxylase 67 (GAD67), dendritic arbors and spine density in cortex and hippocampus, and abnormalities in synaptic function including long-term potentiation (LTP). In spite of these abnormalities, behavioral abnormalities in +/rl are subtle and controversial. Recent findings indicate that the reelin (RELN) and GAD67 promoters are hypermethylated in GABAergic neurons of psychotic postmortem brain and that DNA methyltransferase 1 (DNMT1) is up-regulated. Hypermethlyation of RELN and GAD67 promoters can be induced by treating mice with methionine, and these mice display brain and behavioral abnormalities similar to +/rl. Thus, an animal model that combines genetic heterozygocity with epigenesis holds promise for understanding the role of Reelin down-regulation in psychosis.

Animals↗
PubMed2006

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Antipsychotic Agents↗
PubMed2006

An evaluation of the performance of the self-rating of the effects of alcohol questionnaire in 12- and 35-year-old subjects.

OBJECTIVE: A low level of response (LR) to alcohol was originally established through evidence of less alcohol-related change in several parameters at a given blood alcohol level. This is a genetically influenced phenotype associated with an increased risk for alcoholism. When measured by a retrospective questionnaire (the Self-Rating of the Effects of Alcohol [SRE] scale), a lower LR (here indicated by a report that more drinks were historically needed for various effects) correlates with a family history of alcoholism and numerous alcohol use-related variables. The current analyses address the questions of how higher SRE scores (as indicators of a low LR) relate to alcohol use and problems across different age groups and when considered in the context of demography (e.g., age, gender, and weight), as well as the number of items endorsed on the questionnaire. METHOD: SRE data (scores and numbers of items endorsed), demography, and alcohol-related variables (quantity, frequency, and problems) were evaluated in two populations. The first population included 334 12-year-old children from the Avon Longitudinal Study of Parents and Children, and the second included more than 400 35-year-old men from the San Diego Prospective Study. In each group, Pearson correlations were established among all variables, and items that were significantly linked to alcohol-related outcomes were entered into regression analyses as predictors of these outcomes. RESULTS: In both samples, SRE scores correlated with all alcohol-related outcomes, with the highest values for the maximum quantity of alcohol consumed. Relationships between the SRE score and alcohol-related variables remained robust in both populations when entered into regression analyses incorporating demography and the number of SRE items answered by subjects. CONCLUSIONS: The SRE score appears to perform relatively similarly across the two populations regarding relationships with alcohol quantity, frequency, and problems. The most consistent results were observed for the maximum quantity of alcohol consumed.

Adolescent↗
PubMed2006

Concomitant medications may not improve outcome of antipsychotic monotherapy for stabilized patients with nonacute schizophrenia.

BACKGROUND: There are virtually no controlled data suggesting that concomitant psychotropic medications (CPMs) improve outcome in schizophrenia after the acute phase. Despite that, polypharmacy (with all of its disadvantages) is far more common than monotherapy. To our knowledge, there have been no published reports of prospective systematic investigations of the efficacy of unrestricted CPM use in nonacute schizophrenia. METHOD: This was a naturalistic, systematic study using a sample of 53 stabilized patients with DSM-IV-TR schizophrenia from 1 clinical practice setting including both private patients and patients from controlled research studies of the effectiveness of antipsychotics. Since there are meager controlled or systematic data on the effectiveness of CPM use with antipsychotics in nonacute schizophrenia, we tested the clinical strategy of CPM use by gradually tapering all CPMs (except antianxiety agents). The aim was to determine if the CPM improved outcome, had no effect, or worsened outcome using the Clinical Global Impressions-Improvement scale before and after taper, over at least 3 months and in some cases up to 18 months after discontinuation. Data were gathered from July 2002 to June 2005. RESULTS: For 21 patients undergoing 22 antidepressant tapers, no change was noted in 18 of 22 tapers, while in 3 improvement was noted and in 1 worsening was noted. For the 12 patients on treatment with mood stabilizers, no change was noted in 10 of 13 discontinuations, while in 3 mild worsening was noted. One patient was on treatment with both modafinil and trazodone and reported no change after tapering each in separate discontinuation trials, while another 3 patients were taking sleeping medications and also noted no change after discontinuation. CONCLUSION: For most stabilized, chronic patients with schizophrenia, tapering adjunctive medications did not change outcome. This naturalistic study further defines the limits of efficacy of some concomitant classes of medications in patients with chronic schizophrenia who are already receiving adequate antipsychotic therapy.

Adolescent↗
PubMed2006

Relapse of aggressive and disruptive behavior in mentally retarded adults following antipsychotic drug withdrawal predicts psychotropic drug use a decade later.

BACKGROUND: Mental retardation is frequently associated with aggression toward self and others. Antipsychotic medications are frequently used as a major treatment of such aggression. However, national and state policies and guidelines are weighted toward stopping or decreasing the doses of these medications whenever possible, although exceptions are permitted. The purpose of this study was to determine if relapse during or after antipsychotic drug withdrawal in mentally retarded adults predicts continuing antipsychotic drug use an average of a decade later. METHOD: We report here on a 6- to 13-year (average 10-year) follow-up of 151 institutionalized mentally retarded adults. During the period 1990-1997, the subjects had been prescribed antipsychotic medications to treat maladaptive behaviors, primarily consisting of aggression, disruptive/destructive behaviors, or a combination of these. We compared subjects' psychotropic medication profiles in 2003 as they related to outcome during the earlier period. Our goal was to determine if rapid relapse (a clinically significant increase in maladaptive target symptoms, beginning 3 months or less after antipsychotic drug termination or dosage reduction, that was reversed by antipsychotic drug reinstitution or dosage increases) during or after routine withdrawal of an antipsychotic predicted psychotropic drug use in 2003. RESULTS: For those individuals successfully withdrawn from antipsychotic medications, 66.3% (55/83) were still psychotropic drug free in 2003. For those who rapidly relapsed during the period 1990-1997 following antipsychotic drug withdrawal or dosage decreases, only 9.0% (5/55) were psychotropic medication free in 2003. CONCLUSION: These observations support policies and guidelines indicating that attempts to stop treatment with antipsychotic medications in mentally retarded individuals are worthwhile. However, the results also indicate that eventual discontinuation of antipsychotic medications in institutionalized mentally retarded adults who have previously relapsed upon such withdrawal is unlikely to be successful. Rigid adherence to drug withdrawal policies and guidelines in such individuals should be reconsidered.

Adult↗
PubMed2006

Omega-3 fatty acids: evidence basis for treatment and future research in psychiatry.

OBJECTIVE: To determine if the available data support the use of omega-3 essential fatty acids (EFA) for clinical use in the prevention and/or treatment of psychiatric disorders. PARTICIPANTS: The authors of this article were invited participants in the Omega-3 Fatty Acids Subcommittee, assembled by the Committee on Research on Psychiatric Treatments of the American Psychiatric Association (APA). EVIDENCE: Published literature and data presented at scientific meetings were reviewed. Specific disorders reviewed included major depressive disorder, bipolar disorder, schizophrenia, dementia, borderline personality disorder and impulsivity, and attention-deficit/hyperactivity disorder. Meta-analyses were conducted in major depressive and bipolar disorders and schizophrenia, as sufficient data were available to conduct such analyses in these areas of interest. CONSENSUS PROCESS: The subcommittee prepared the manuscript, which was reviewed and approved by the following APA committees: the Committee on Research on Psychiatric Treatments, the Council on Research, and the Joint Reference Committee. CONCLUSIONS: The preponderance of epidemiologic and tissue compositional studies supports a protective effect of omega-3 EFA intake, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in mood disorders. Meta-analyses of randomized controlled trials demonstrate a statistically significant benefit in unipolar and bipolar depression (p = .02). The results were highly heterogeneous, indicating that it is important to examine the characteristics of each individual study to note the differences in design and execution. There is less evidence of benefit in schizophrenia. EPA and DHA appear to have negligible risks and some potential benefit in major depressive disorder and bipolar disorder, but results remain inconclusive in most areas of interest in psychiatry. Treatment recommendations and directions for future research are described. Health benefits of omega-3 EFA may be especially important in patients with psychiatric disorders, due to high prevalence rates of smoking and obesity and the metabolic side effects of some psychotropic medications.

Epidemiologic Studies↗
PubMed2005

MHC class I-associated peptides identified from normal platelets and from individuals with idiopathic thrombocytopenic purpura.

Major histocompatibility complex (MHC) class I molecules bind and display peptide antigens on the cell surface. CD8(+) T lymphocytes recognize peptides in association with class I proteins to initiate a cytotoxic immune response. To understand the specificity of such immune responses and to facilitate the development of therapies for disease, it is important to identify MHC-presented peptides. In this study, platelets, easily obtainable and often associated with immune-mediated disease, were selected to identify MHC class I-associated peptides. MHC-associated peptides presented on platelets of normal individuals and individuals with idiopathic thrombocytopenic purpura (ITP) were characterized. ITP is characterized by the premature immune destruction of platelets. It is associated with the production of antiplatelet autoantibodies, most often targeting platelet membrane GPIIb/IIIa or GPIb/IX. In addition to characterizing five fully and several partially sequenced peptides from platelets, the peptide GPRGA(L/I)S(L/I)(L/I) was identified from four of the five ITP patients. The anchor motif of this peptide correlates with the presence of the HLA-B7 allele. A BLAST search identified this peptide as GPIb (4-12). In conclusion, platelets from normal and ITP individuals can present peptides from general cellular proteins and platelet specific proteins, such as GPIb, to the immune system via MHC class I.

Blood Platelets↗
PubMed2005

GABAergic dysfunction in schizophrenia: new treatment strategies on the horizon.

RATIONALE: Cortical gamma-aminobutyric acid (GABA)ergic neurons contribute to the orchestration of pyramidal neuron population firing as follows: (1) by releasing GABA on GABA(A) and GABA(B) receptors, (2) by releasing reelin in the proximity of integrin receptors located on cortical pyramidal neuron dendritic spines, and (3) through reelin contributing to the regulation of dendritic spine plasticity by modulating dendritic resident mRNA translation. In schizophrenia (SZ) and bipolar (BP) postmortem brains, the downregulation of mRNAs encoding glutamic acid decarboxylase 67 (GAD(67)) and reelin decreases the cognate proteins coexpressed in prefrontal cortex (PFC) GABAergic neurons. This finding has been replicated in several laboratories. Such downregulation suggests that the neuropil hypoplasticity found in the PFC of SZ and BP disorder patients may depend on a downregulation of GABAergic function, which is associated with a decrease in reelin secretion from GABAergic neuron axon terminals on dendrites, somata, or axon initial segments of pyramidal neurons. Indirectly, this GABAergic neuron downregulation may play a key role in the expression of positive and negative symptoms of SZ and BP disorders. OBJECTIVES: The above described GABAergic dysfunction may be addressed by pharmacological interventions to treat SZ and BP disorders using specific benzodiazepines (BZs), which are devoid of intrinsic activity at GABA(A) receptors including alpha(1) subunits but that act as full positive allosteric modulators of GABA action at GABA(A) receptors containing alpha(2), alpha(3), or alpha(5) subunits. These drugs are expected to enhance GABAergic signal transduction without eliciting sedation, amnesia, and tolerance or dependence liabilities. RESULTS AND CONCLUSIONS: BZs, such as diazepam, although they are efficient in equilibrating GABA(A) receptor signal transduction in a manner beneficial in the treatment of positive and negative symptoms of SZ, may not be ideal drugs, because by mediating a full positive allosteric modulation of GABA(A) receptors containing the alpha(1) subunit, they contribute to sedation and to the development of tolerance after even a brief period of treatment. In contrast, other BZ-binding site ligands, such as 6-(2bromophenyl)-8-fluoro-4H-imidazo [1,5-a][1,4] benzodiazepine-3-carboxamide (imidazenil), which fail to allosterically and positively modulate the action of GABA at GABA(A) receptors with alpha(1) subunits but that selectively allosterically modulate cortical GABA(A) receptors containing alpha(5) subunits, contribute to the anxiolytic, antipanic, and anticonvulsant actions of these ligands without producing sedation, amnesia, or tolerance. Strong support for the use of imidazenil in psychosis emerges from experiments with reeler mice or with methionine-treated mice, which express a pronounced reelin and GAD(67) downregulation that is also operative in SZ and BP disorders. In mice that model SZ symptoms, imidazenil increases signal transduction at GABA(A) receptors containing alpha(5) subunits and contributes to the reduction of behavioral deficits without producing sedation or tolerance liability. Hence, we suggest that imidazenil may be considered a prototype for a new generation of positive allosteric modulators of GABA(A) receptors, which, either alone or in combination with neuroleptics, should be evaluated in GABAergic dysfunction operative in the treatment of SZ and BP disorders with psychosis.

Animals↗
PubMed2005

Genetic dissection of fusiform rust and pitch canker disease traits in loblolly pine.

Loblolly pine (Pinus taeda L.) exhibits genetic resistance to fusiform rust disease (incited by the biotrophic fungus, Cronartium quercuum f. sp. fusiforme) and pitch canker disease (incited by the necrotrophic fungus, Fusarium circinatum). In this study, a total of 14,015 loblolly pine cuttings from 1,065 clones were screened in controlled greenhouse conditions to identify phenotypes of clones, families, and parents that guide a genetic dissection of disease traits associated with pitch canker and fusiform rust. A total of 23,373 phenotypic data points were collected for lesion length (pitch canker) and gall score, gall length, and gall width (fusiform rust). We verified heritable fusiform rust and pitch canker traits and calculated parental, clonal, and full-sib family rankings for both diseases. Genetic correlations revealed that traits associated with fusiform rust are genetically distinct from one another, and that the genetic mechanisms underlying pitch canker and fusiform rust resistance are independent. The disease phenotyping described here is a critical step towards identifying specific loci and alleles associated with fusiform rust and pitch canker resistance.

Analysis of Variance↗
PubMed2005

In psychosis, cortical interneurons overexpress DNA-methyltransferase 1.

Cortical DNA-methyltransferase 1 (DNMT1) is preferentially expressed in interneurons secreting GABA where it very likely contributes to promoter CpG island hypermethylation, thus causing a down-regulation of promoter functions. To consolidate and expand on previous findings that, in the cortex of schizophrenia (SZ) brains, glutamic acid decarboxylase 67 (GAD67) expression is down-regulated whereas that of DNMT1 is up-regulated, we studied both parameters in Brodmann's area (BA) 9 from the McLean 66 Cohort Collection (Harvard Brain Tissue Resource Center, Belmont, MA). In BA9 of SZ and bipolar disorder patients with psychosis, DNMT1 mRNA and protein expression preferentially increases in layer I, II, and IV interneurons, and this increase is paralleled by a decreased number of GAD67 mRNA-positive neurons. The increase in DNMT1 and the decrease in GAD67-expressing neurons were unrelated to postmortem interval, pH, RNA quality, or to the presence, dose, or duration of antipsychotic (APS) medication, with the exception of a subgroup of SZ patients treated with a combination of valproate and APS in which the expression of DNMT1 failed to change. The DNMT1 increase and the GAD67 decrease in BA9 interneurons are significant features of SZ and bipolar disorder with psychosis. Interestingly, the DNMT1 increase failed to occur when patients with psychosis received a combination of valproate and APS treatment but not APS monotherapy.

Adult↗
PubMed2005

Diagnosis and treatment of depression in patients with mental retardation.

Depression in mentally retarded individuals is not uncommon and usually is treatable. However, studies of the diagnosis and treatment of psychiatric illnesses in general and depression specifically in this population are relatively rare. Although Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria can be applied to mildly and moderately retarded individuals, the diagnosis of depression in those with intelligence quotients below 35 is challenging. However, the diagnosis of depression in the latter group is possible using modified criteria emphasizing observational data. Criteria include symptoms such as sadness, irritability, decreased social interaction, regression of skills, sleep disturbances, diurnal variation, and aggression. Furthermore, there is a growing body of evidence that antidepressant treatments, especially administration of selective serotonin reuptake inhibitors, are effective in treating depression in mentally retarded patients. This article reviews numerous studies elaborating on the diagnosis, phenomenology, and treatment of depression in mentally retarded individuals.

Aggression↗