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Biomedical subjects

M Abrams

Publications and source records attributed to M Abrams.

At least 19 recordsLinked to original sources
PubMed2001

Design and biological activity of (S)-4-(5-([1-(3-chlorobenzyl)-2-oxopyrrolidin-3-ylamino]methyl)imidazol-1-ylmethyl)benzonitrile, a 3-aminopyrrolidinone farnesyltransferase inhibitor with excellent cell potency.

The synthesis, structure-activity relationships, and biological properties of a novel series of imidazole-containing inhibitors of farnesyltransferase are described. Starting from a 3-aminopyrrolidinone core, a systematic series of modifications provided 5h, a non-thiol, non-peptide farnesyltransferase inhibitor with excellent bioavailability in dogs. Compound 5h was found to have an unusually favorable ratio of cell potency to intrinsic potency, compared with other known FTIs. It exhibited excellent potency against a range of tumor cell lines in vitro and showed full efficacy in the K-rasB transgenic mouse model.

Alkyl and Aryl Transferases↗
PubMed2001

Francisella tularensis strain typing using multiple-locus, variable-number tandem repeat analysis.

Francisella tularensis, the etiological agent of tularemia, is found throughout the Northern hemisphere. After analyzing the F. tularensis genomic sequence for potential variable-number tandem repeats (VNTRs), we developed a multilocus VNTR analysis (MLVA) typing system for this pathogen. Variation was detected at six VNTR loci in a set of 56 isolates from California, Oklahoma, Arizona, and Oregon and the F. tularensis live vaccine strain. PCR assays revealed diversity at these loci with total allele numbers ranging from 2 to 20, and Nei's diversity index values ranging from 0.36 to 0.93. Cluster analysis identified two genetically distinct groups consistent with the current biovar classification system of F. tularensis. These findings suggest that these VNTR markers are useful for identifying F. tularensis isolates at this taxonomic level. In this study, biovar B isolates were less diverse than those in biovar A, possibly reflecting the history of tularemia in North America. Seven isolates from a recent epizootic in Maricopa County, Ariz., were identical at all VNTR marker loci. Their identity, even at a hypervariable VNTR locus, indicates a common source of infection. This demonstrates the applicability of MLVA for rapid characterization and identification of outbreak isolates. Future construction of reference databases will allow faster outbreak tracking as well as providing a foundation for deciphering global genetic relationships.

Animals↗
PubMed2001

Computer-guided surgery utilizing a computer-milled surgical template.

The primary objective of implant placement is to support prosthetic restorations that return patients to proper oral form, function, and aesthetics. Since correct implant placement can be a technique-sensitive process, it is performed in conjunction with various diagnostic and guidance procedures. For accurate diagnosis, radiographic templates, computed tomography scans, and surgical simulation software are unparalleled. This article demonstrates the manner by which computer-guided surgery and computer-milled surgical templates can enable precise implant placement for the entire implant team.

Alveolar Process↗
PubMed2001

Systematic finger guided transrectal needle biopsies of the prostate--alternative to TRUS guided biopsies in clinical practice.

OBJECTIVE: To prospectively evaluate the efficacy of a Systematic Finger Guided (SFG) approach to transrectal Prostate Needle Biopsy (PNB). PATIENTS AND METHODS: One hundred and eighty-nine sets of SFG PNB were performed on 145 men. At least four biopsy cores were taken systematically from apex to base on each side of the prostate, including suspicious areas if present. The SFG experience was compared to a literature cohort and to 14 patients who had both SFG and TRUS guided PNB. RESULTS: Of 111 SFG biopsy sets taken from 88 men with suspicious DRE, 53% were positive; 25%, 43% and 84% of men had a PSA of 0-4, 4.1-10 and >10 ng/ml respectively. With benign DRE's, positive biopsies were seen in 22% and 28% of those with a PSA 4.1-10 and >10 ng/ml respectively. Of 22 patients with two or more sets of SFG PNB's, 11 (50%) were positive on repeat PNB. Of the 14 patients with a mix of TRUS and SFG PNB's, six were concordant, four were positive on SFG only, and one on TRUS only (p=n.s.). CONCLUSION: Results of SFG PNB's and TRUS PNB's are equivalent in patients with and without suspicious prostates on DRE, probably due to the systematic nature of the sampling and number of the samples taken.

Biopsy, Needle↗
PubMed2000

Depression and functioning in relation to health care use in sickle cell disease.

The purpose of the current study was to investigate depression and health care use in patients with sickle cell disease (SCD). Forty-four adults with SCD were interviewed and data from 43 participants, both with (n = 11) and without (n = 32) depression, were used for further analyses. Data from one potential subject were excluded on the basis of diagnosis. The full evaluation included the Structured Clinical Interview for DSM-III-R Disorders (SCID) and the Center for Epidemiologic Studies--Depression Scale (CES-D), as well as measures of psychosocial and behavioral functioning. Good between-instrument agreement was found between the self-report and interview-based measures of depression. However, the functioning data did not entirely support the use of a more stringent cutoff score on the CES-D. Findings suggest that the purpose of the evaluation should be factored into the decision-making process when determining which cutoff score should be utilized (i.e. what is the cost-benefit ratio for false-positives vs. false-negatives). A series of hierarchical regression analyses supported the finding that disease severity alone does not explain the level of functioning displayed by patients. More importantly, the patient's perceived functioning was the best indicator of health care use within a 1-year period. Furthermore, specific interventions that target negative thinking and distorted cognitions, as well as provide psychoeducation, such as cognitive-behavioral therapy, need to be further explored within this population.

Activities of Daily Living↗
PubMed2000

Executive dysfunction predicts nonresponse to fluoxetine in major depression.

BACKGROUND: Functional brain imaging studies of major depression have consistently revealed hypometabolism or hypoperfusion in specific regions of the prefrontal cortex and basal ganglia. Studies of cognitive functioning in major depression have suggested that some but not all subjects exhibit cognitive deficits that are consistent with frontal-subcortical dysfunction, although the reasons for this heterogeneity are unclear. In this study, we explored this heterogeneity among depressed subjects by examining the relationship between cognitive functioning and treatment outcome. METHOD: Subjects with major depression were administered a complete neuropsychological test battery prior to treatment with fluoxetine. RESULTS: There were no significant differences between responders and nonresponders to fluoxetine in terms of age, educational achievement, number of past episodes of depression, and estimated premorbid IQ. However, nonresponders performed significantly worse than responders on several pretreatment measures of executive functioning, after controlling for baseline group differences in depression severity. LIMITATIONS: The results are based on a small sample of primarily female subjects, resulting in low statistical power and less generalizability to samples of male subjects with depression. CONCLUSIONS: The findings suggest that subtle prefrontal dysfunction in subjects with major depression may be predictive of poor response with particular medications. Assessment of the executive functions may play a particular role in pretreatment identification of subjects likely to respond to specific medications.

Adult↗
PubMed2000

Investigation of nonlinear ECoG changes during spontaneous sleep state changes and cortical arousal in fetal sheep.

We examined the processes of cortical activation and deactivation of the fetal brain during spontaneous sleep state transitions and during central nervous processing of vibroacoustic stimulations (VASs) using nonlinear analysis of the electrocorticogram (ECoG). Tests of nonlinearity and a random shuffling routine revealed deterministic and nonlinear portions in the fetal ECoG. As common nonlinear measures are not applicable to nonstationary time series, we developed an algorithm to estimate the predictability of the ECoG in its time course by means of a point prediction error (PPE). The ECoG was recorded before and during VAS from the maternal abdominal surface in seven chronically instrumented fetal sheep at 0.8 of gestation. The PPE during REM sleep was significantly higher than during NREM sleep. VAS in NREM sleep resulted in an abrupt increase of the PPE not reaching the level of REM sleep. The steep increase of the PPE at onset and its slow decrease after cessation of the stimulus were very similar to the dynamics of spontaneous sleep state transitions, suggesting the involvement of the same cortical activating mechanisms. In conclusion, the stage and the time course of fetal brain activation and deactivation patterns can be clearly shown by PPE techniques. The PPE is a useful complement to spectral analysis. Both techniques describe different properties of the ECoG.

Alpha Rhythm↗
PubMed1999

Neurophysiologic predictors of treatment response to fluoxetine in major depression.

Treatment with antidepressants is marked by heterogeneity of response; predicting individual response to any given agent remains problematic. Neuroimaging studies suggest that response is accompanied by physiologic changes in cerebral energy utilization, but have not provided useful markers at pretreatment baseline. Using quantitative EEG (QEEG) techniques, we investigated pretreatment neurophysiologic features to identify responders and non-responders to fluoxetine. In a double-masked study, 24 adult subjects with current major depression of the unipolar type were studied over 8 weeks while receiving fluoxetine (20 mg QD) or placebo. Neurophysiology was assessed with QEEG cordance, a measure reflecting cerebral energy utilization. Response was determined with rating scales and clinical interview. Subjects were divided into discordant and concordant groups based upon the number of electrodes exhibiting discordance. The concordant group had a more robust response than the discordant group, judged by lower final Hamilton Depression (HAM-D) mean score (8.0+/-7.5 vs. 19.6+/-4.7, P = 0.01) and final Beck Depression Inventory (BDI) mean score (14.0+/-9.4 vs. 27.8+/-3.7, P = 0.015), and by faster reduction in symptoms (HAM-D: 14.0+/-5.0 vs. 23.8+/-4.1, P = 0.004 at 1 week). Groups did not differ on pretreatment clinical or historical features. Response to placebo was not predicted by this physiologic measure. We conclude that cordance distinguishes depressed adults who will respond to treatment with fluoxetine from those who will not. This measure detects a propensity to respond to fluoxetine and may indicate a more general responsiveness to antidepressants.

Adult↗
PubMed1999

Phosphorylation of linker histone H1 regulates gene expression in vivo by mimicking H1 removal.

Two Tetrahymena strains were created by gene replacement. One contained H1 with all phosphorylation sites mutated to alanine, preventing phosphorylation. The other had these sites changed to glutamic acid, mimicking the fully phosphorylated state. Global gene expression was not detectably changed in either strain. Instead, H1 phosphorylation activated or repressed specific genes in a manner that was remarkably similar to the effects of knocking out the gene encoding H1. These studies demonstrate a role for H1 phosphorylation in the regulation of transcription in vivo and suggest that it acts by mimicking the partial removal of H1.

Animals↗
PubMed1999

Characteristics and perceived needs of mothers with serious mental illness.

This cross-sectional survey determined the prevalence of motherhood among severely mentally ill women hospitalized in an inner-city facility and examined the demographic characteristics and perceived needs of the 32 mothers who were identified. Slightly less than one-quarter of these mothers had seen their children within the last week, and only about 20 percent maintained full custody of their children. However, none of the respondents reported feeling that it was unimportant whether they continued mothering their children. Approximately half described needing help in dealing with their sadness about their children. The pilot data presented in this paper suggest that motherhood is common among severely mentally ill and hospitalized women and that issues relevant to mothering remain important to them.

Adult↗
PubMed1998

Altered cerebral energy utilization in late life depression.

BACKGROUND: Global and regional changes in cerebral energy utilization are reported to characterize late life depression. METHODS: Twenty seven subjects with late life depression (9 prior to starting medication, 18 after starting) and 27 matched controls were evaluated with cordance, a quantitative EEG measure that reflects cerebral energy utilization. RESULTS: Global and focal (anterior and centrotemporal) differences were present in theta-band cordance between unmedicated depressed and control subjects. Depressed subjects receiving treatment had cordance patterns similar to controls. CONCLUSIONS: The presence of both diffuse and focal disturbances in energy utilization prior to initiating treatment indicates that cordance detects altered cerebral physiology in depressed patients, and that this measure may also be sensitive to treatment interventions.

Age Factors↗
PubMed1998

In vitro circumvention of cisplatin resistance by the novel sterically hindered platinum complex AMD473.

A novel sterically hindered platinum complex, AMD473 [cis-aminedichloro(2-methylpyridine) platinum (II)], has been selected for phase I clinical trials due to commence in 1997. AMD473 was rationally designed to react preferentially with nucleic acids over sulphur ligands such as glutathione. This report documents the in vitro circumvention of acquired cisplatin resistance mechanisms in human ovarian carcinoma (HOC) cell lines by AMD473. In a panel of 11 HOC cell lines, AMD473 showed intermediate growth inhibition potency (mean IC50 of 8.1 microM) in comparison to cisplatin (mean IC50 of 2.6 microM) and carboplatin (mean IC50 of 20.3 microM). AMD473 showed only a 30.7-fold increase in IC50 value from the most sensitive to the most resistant HOC cell line, whereas for cisplatin it was 117.9-fold and for carboplatin 119.7-fold. AMD473 also showed significantly (P < 0.05) reduced cross-resistance to cisplatin in a panel of three cell lines with known acquired platinum drug resistance mechanisms (mean RF for AMD473 was 1.9, for cisplatin 9.1). Cellular accumulation of AMD473 was not reduced in two HOC cell lines (A2780cisR and 41McisR), in which reduced cisplatin accumulation is a major mechanism of acquired cisplatin resistance. AMD473 naked-DNA binding was significantly less affected (P < 0.05) than that of cisplatin by the presence of 5 mM glutathione. Also, AMD473 almost completely circumvented acquired cisplatin resistance in a cell line (A2780cisR) with fivefold elevated intracellular glutathione levels compared with the parent A2780 cell line when measured by clonogenic assay (RF 4.5 for AMD473 vs RF 18 for cisplatin). AMD473 also showed a lower increase in IC50 than cisplatin in an A2780 cell line model with artificially elevated glutathione levels. AMD473 DNA binding was slower than that of cisplatin on both naked and cellular DNA. AMD473 also formed DNA interstrand cross-links (ICLs) at a slower rate than cisplatin (peak ICL formation was at 5 h for cisplatin vs > or = 14 h for AMD473) after equitoxic doses were exposed to HOC cells for 2 h. AMD473 ICLs in the CH1 HOC cell line were slowly formed and showed no visible signs of being repaired 24 h after removal of drug. This was paralleled by a slower, longer lasting induction of p53 protein by equitoxic doses of AMD473 in HOC cell lines with wild-type p53. This new class of sterically hindered platinum compound, selected for clinical trial in 1997, may therefore elicit improved clinical response in intrinsically and acquired cisplatin-resistant tumours in the clinic.

Antineoplastic Agents↗
PubMed1998

Chemical, biochemical and pharmacological activity of the novel sterically hindered platinum co-ordination complex, cis-[amminedichloro(2-methylpyridine)] platinum(II) (AMD473).

cis-[Amminedichloro(2-methylpyridine)] platinum(II) (AMD473) is a novel sterically hindered anti-tumour compound designed to circumvent platinum drug resistance and is due to begin clinical trials in 1997. This paper reports the rationale behind the development of AMD473 with regard to its chemical and DNA binding properties. AMD473 circumvents resistance in vitro in acquired cisplatin resistant human ovarian carcinoma (HOC) cell line models (2 h SRB assay mean resistance factor = 2.8 +/- 1.2 microM for AMD473, versus 6.5 +/- 3.5 microM for cisplatin). AMD473 was chosen from a panel of sterically hindered 'pyridine platinum complexes' due to its reduced reactivity with sulphur ligands, unique DNA binding properties and ability to circumvent several of the major resistance mechanisms that manifest in cisplatin-resistant tumour cell lines. AMD473 hydrolyses more slowly (aquation rate = 1.47 +/- 0.32 x 10(-5) s-1 for AMD473 versus 2.98 +/- 0.6 x 10(-5) s-1 for cisplatin) in water than cisplatin and is also shown to have a reduced preference for reaction with soft nucleophiles such as sulphur ligands. Although AMD473 has similar DNA sequence specificity to cisplatin in DNA extracted from drug-treated tumour cells, several adducts unique to AMD473 were formed on naked plasmid DNA. AMD473 was shown to form DNA interstrand cross-links (ICLs) in both naked pBR322 plasmid and SKOV-3 cellular DNA, although AMD473 formed ICLs at a much slower rate than cisplatin. As steric hindrance was increased from AMD494 (unsubstituted pyridine) through AMD473 to AMD508 (2,6-dimethylpyridine), by addition of methyl groups on the pyridine ligand, cross-link formation rates became slower. By alkaline elution, at equimolar doses, AMD473 ICL formation after 24 h incubation was less than that of cisplatin after 4 h. Understanding the chemical and biochemical properties of these sterically hindered platinum complexes may aid the development of more novel platinum chemotherapeutic agents capable of further improving anti-tumour activity in resistant tumours.

Antineoplastic Agents↗