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Biomedical subjects

M Williams

Publications and source records attributed to M Williams.

At least 253 records · Page 14Linked to original sources
PubMed1998

Expression of a uracil DNA glycosylase (UNG) inhibitor in mammalian cells: varicella-zoster virus can replicate in vitro in the absence of detectable UNG activity.

Uracil DNA glycosylase (UNG) functions as a DNA repair or proofreading enzyme. The UNG gene is present in nearly all prokaryotes and eukaryotes screened to date and is found in herpesviruses and poxviruses. Prior studies showed that viral UNG is essential for poxvirus replication. Although viral UNG is not required for herpesvirus replication, cellular UNG was thought to be essential for virus replication. To study the role of UNG in herpesvirus replication, we first showed that varicella-zoster virus (VZV) ORF59 encodes a functional UNG. We then constructed a VZV mutant with a deletion in the UNG gene and showed that the mutant was unimpaired for replication in vitro. Because cultured cells express their own endogenous UNG, we next inserted a bacteriophage UNG inhibitor UGI gene into the VZV genome. Infection of cells with VZV lacking viral UNG and expressing UGI completely abrogated detectable cellular UNG activity in vitro. Parental VZV, VZV lacking viral UNG, and VZV expressing UGI all grew to similar titers in cell culture, indicating that VZV can replicate in vitro in the absence of detectable viral or cellular UNG activity.

Cell Nucleus↗
PubMed1998

Health authorities, GDPs and TECs: a partnership for general dental practice development.

Major changes will occur in primary dental care over the next 5 to 10 years. These changes present a series of possible opportunities and threats to dental practices. This paper reports on how the health authority, the local training and enterprise council (TEC) and five general dental practices in North Cheshire worked collaboratively to support the development of the practices. Health authorities and dentists should be aware of the possibility of working with TECs to support general dental practice development.

Communication↗
PubMed1998

Kampanols: novel Ras farnesyl-protein transferase inhibitors from Stachybotrys kampalensis.

Farnesyl-protein transferase (FPTase) is a critical enzyme that participates in the post-translational modification of the Ras protein. Inhibitors of this enzyme have the potential of being novel anticancer agents for tumors in which the ras oncogene is found mutated and contributes to cell transformation. Continued screening of natural product extracts led to the isolation of kampanols, which are novel and specific inhibitors of FPTase. The most active kampanols exhibited IC50 values between 7 to 13 microM against human recombinant FPTase. The isolation, structure determination, and biological activity of these compounds are described.

Alkyl and Aryl Transferases↗
PubMed1998

Identification of inbred mouse strains harboring genetic modifiers of mammary tumor age of onset and metastatic progression.

Metastasis is one of the most important and complex processes in human neoplastic disease. A large number of both positive and negative events must occur to permit a tumor cell to colonize a distant site successfully. To identify mouse strains that harbor dominant genetic modifiers of this process, a strain survey was initiated utilizing a transgenic mouse mammary tumor model that exhibits a high incidence of pulmonary metastases. The transgenic animal was bred to 27 different inbred strains of mice and scored for the metastatic organ tropism and metastatic density. Thirteen strains were identified that had a statistically significant reduction in the numbers of pulmonary metastases. In addition, 10 strains were identified that altered the kinetics of induction of the primary mammary tumor. These strains will likely provide useful model systems for the analysis of genetic interactions in the initiation and progression of mammary adenocarcinomas.

Age of Onset↗
PubMed1998

Human autoantibodies specific for the alpha1A calcium channel subunit reduce both P-type and Q-type calcium currents in cerebellar neurons.

The pharmacological properties of voltage-dependent calcium channel (VDCC) subtypes appear mainly to be determined by the alpha1 pore-forming subunit but, whether P-and Q-type VDCCs are encoded by the same alpha1 gene presently is unresolved. To investigate this, we used IgG antibodies to presynaptic VDCCs at motor nerve terminals that underlie muscle weakness in the autoimmune Lambert-Eaton myasthenic syndrome (LEMS). We first studied their action on changes in intracellular free Ca2+ concentration [Ca2+]i in human embryonic kidney (HEK293) cell lines expressing different combinations of human recombinant VDCC subunits. Incubation for 18 h with LEMS IgG (2 mg/ml) caused a significant dose-dependent reduction in the K+-stimulated [Ca2+]i increase in the alpha1A cell line but not in the alpha1B, alpha1C, alpha1D, and alpha1E cell lines, establishing the alpha1A subunit as the target for these autoantibodies. Exploiting this specificity, we incubated cultured rat cerebellar neurones with LEMS IgG and observed a reduction in P-type current in Purkinje cells and both P- and Q-type currents in granule cells. These data are consistent with the hypothesis that the alpha1A gene encodes for the pore-forming subunit of both P-type and Q-type VDCCs.

Animals↗
PubMed1998

Induction of IGF-1 mRNA expression following traumatic injury to the postnatal brain.

A variety of adult, non-neural tissues respond to injury by increasing expression of the gene which encodes for insulin-like growth factor-1 (IGF-1). This response is thought to be a key component in the regenerative capacity of these tissues. In contrast, the central nervous system (CNS) has relatively little regenerative capacity following injury. Interestingly, compared to many non-neuronal tissues, little IGF-1 mRNA can be detected in the adult CNS, raising the possibility that its lack of regenerative capacity is related its relative lack of IGF-1 expression. However, in the 2-week-old adolescent CNS IGF-1 mRNA can be detected in numerous brain regions. Therefore, the purpose of this study was to determine the responsiveness of the IGF-1 gene to injury in adolescent CNS tissue, a period in which expression of this gene is relatively abundant. Expression of IGF-1 mRNA was measured by means of a sensitive solution hybridization/RNase protection assay in the parieto-occipital lobes of 2-week-old and adult mice following penetrating injury. Levels of IGF-1 transcript in the injured brains were significantly increased above those of controls in both 2-week-old and adult brains 3-day post injury and remained elevated for 1 week after injury. These observations demonstrate that the adult CNS, like other tissues, can respond to injury by increasing expression of IGF-1 mRNA.

Age Factors↗
PubMed1998

Antinociceptive effects of the novel neuronal nicotinic acetylcholine receptor agonist, ABT-594, in mice.

ABT-594 [5-((2R)-azetidinylmethoxy)-2-chloropyridine], a novel neuronal nicotinic acetylcholine receptor agonist, produced significant antinociceptive effects in mice against both acute noxious thermal stimulation--the hot-plate and cold-plate tests--and persistent visceral irritation--the abdominal constriction (writhing) assay (maximally-effective dose in each test 0.62 micromol/kg, i.p.). This effect was not stereoselective since the S-enantiomer, A-98593 [5-((2S)-azetidinylmethoxy)-2-chloropyridine], produced similar antinociceptive effects in this dose range. The effect in the hot-plate test peaked at 30 min after i.p. administration and was still present 60 min, but not 120 min, after injection. ABT-594 was orally active, but 10-fold less potent by this route than after i.p. administration. The antinociceptive effect of ABT-594 was prevented, but not reversed, by the noncompetitive neuronal nicotinic acetylcholine receptor antagonist mecamylamine (5 micromol/kg, i.p.). In contrast, the antinociceptive effect of ABT-594 was not prevented by hexamethonium (10 micromol/kg, i.p.), a neuronal nicotinic acetylcholine receptor antagonist that does not readily enter the central nervous system, nor by naltrexone (0.8 micromol/kg), an opioid receptor antagonist. Thus, initiation of antinociception by ABT-594 involves activation of central nicotinic acetylcholine receptors, but does not require activation of naltrexone-sensitive opioid receptors. The antinociceptive effects of morphine and ABT-594 in the mouse hot-plate test appeared to be additive, but ABT-594 did not potentiate the respiratory depression produced by morphine when the two compounds were coadministered. ABT-594 reduced body temperature and spontaneous exploration in the antinociceptive dose range, but did not reliably impair motor coordination in the rotarod test. Thus, it is unlikely that the antinociceptive effects result simply from impaired motor function. The compound also produced an anxiolytic-like effect in the elevated plus maze (at 0.019 and 0.062 micromol/kg, i.p.). Preliminary safety testing revealed an ED50 for overt seizure production of 1.9 micromol/kg, i.p. and an LD50 of 19.1 micromol/kg i.p. in mice, values 10 and 100 times the minimum effective antinociceptive dose of the compound. ABT-594 increased the duration of ethanol-induced hypnotic effects, tended to increase pentobarbital-induced hypnotic effects (P = 0.0502), and had no effect on pentobarbital-induced lethality. These data indicate that ABT-594 is a centrally acting neuronal nicotinic acetylcholine receptor agonist with potent antinociceptive and anxiolytic-like effects in mice.

Analgesics, Non-Narcotic↗
PubMed1998

Identification and initial structure-activity relationships of (R)-5-(2-azetidinylmethoxy)-2-chloropyridine (ABT-594), a potent, orally active, non-opiate analgesic agent acting via neuronal nicotinic acetylcholine receptors.

New members of a previously reported series of 3-pyridyl ether compounds are disclosed as novel, potent analgesic agents acting through neuronal nicotinic acetylcholine receptors. Both (R)-2-chloro-5-(2-azetidinylmethoxy)pyridine (ABT-594, 5) and its S-enantiomer (4) show potent analgesic activity in the mouse hot-plate assay following either intraperitoneal (i.p.) or oral (p.o.) administration, as well as activity in the mouse abdominal constriction (writhing) assay, a model of persistent pain. Compared to the S-enantiomer and to the prototypical potent nicotinic analgesic agent (+/-)-epibatidine, 5 shows diminished activity in models of peripheral side effects. Structure-activity studies of analogues related to 4 and 5 suggest that the N-unsubstituted azetidine moiety and the 2-chloro substituent on the pyridine ring are important contributors to potent analgesic activity.

Administration, Oral↗
PubMed1998

Broad-spectrum, non-opioid analgesic activity by selective modulation of neuronal nicotinic acetylcholine receptors.

Development of analgesic agents for the treatment of severe pain requires the identification of compounds that are devoid of opioid receptor liabilities. A potent (inhibition constant = 37 picomolar) neuronal nicotinic acetylcholine receptor (nAChR) ligand called ABT-594 was developed that has antinociceptive properties equal in efficacy to those of morphine across a series of diverse animal models of acute thermal, persistent chemical, and neuropathic pain states. These effects were blocked by the nAChR antagonist mecamylamine. In contrast to morphine, repeated treatment with ABT-594 did not appear to elicit opioid-like withdrawal or physical dependence. Thus, ABT-594 may be an analgesic that lacks the problems associated with opioid analgesia.

Analgesics, Non-Narcotic↗
PubMed1998

Prepubertal and early adolescent bipolarity differentiate from ADHD by manic symptoms, grandiose delusions, ultra-rapid or ultradian cycling.

BACKGROUND: In contrast to differential diagnosis (ddx) of older adolescent and adult bipolarity (BP), which includes schizophrenia and substance use disorders, the main ddx of prepubertal and early adolescent BP is attention-deficit disorder with hyperactivity (ADHD). To address this ddx issue, and to provide prepubertal mania manifestations, interim baseline data are presented from the National Institute of Mental Health (NIMH)-funded study 'Phenomenology and Course of Pediatric Bipolarity'. METHODS: Data are from the first 60 BP and the first 60 ADHD cases from 270 consecutively ascertained subjects (90 BP, 90 ADHD and 90 community controls). Comprehensive assessments included the Washington University at St. Louis Kiddie and Young Adult-Schedule for Affective Disorders and Schizophrenia--Lifetime and Present Episode Version-DSM-IV (WASH-U-KSADS) blindly administered by nurses to mothers about their offspring and to children/adolescents about themselves. Caseness was established by consensus conferences that included diagnostic and impairment data, teacher and school reports, agency records, videotapes and medical charts. RESULTS: Mean baseline age of BP cases was 11.0+/-2.7 years and the mean age at onset of BP was 8.1+/-3.5 years. Elated mood, grandiosity, hypersexuality, decreased need for sleep, racing thoughts and all other mania items except hyperenergetic and distractibility were significantly and substantially more frequent among BP than ADHD cases (e.g., elation: 86.7% BP vs. 5.0% ADHD; grandiosity: 85.0% BP vs. 6.7% ADHD). In the BP group, 55.0% had grandiose delusions, 26.7% had suicidality with plan/intent and 83.3% were rapid, ultra-rapid or ultradian cyclers. LIMITATIONS: Sites for consecutive case ascertainment from the lowest socioeconomic status classes were unavailable due to current health care policies. CLINICAL RELEVANCE: Prepubertal and early adolescent BP cases differentiate from ADHD by mania-specific criteria and commonly present with ultra-rapid or ultradian cycling.

Activity Cycles↗
PubMed1998

Prepubertal and young adolescent bipolarity versus ADHD: assessment and validity using the WASH-U-KSADS, CBCL and TRF.

BACKGROUND: This addendum to 'Prepubertal and early adolescent bipolarity differentiate from ADHD by mania criteria; grandiose delusions; ultra-rapid or ultradian cycling' (in this volume) provides (1) a description of Washington University at St. Louis Kiddie Schedule for Affective Disorders and Schizophrenia (WASH-U-KSADS) with sample sections (hypersexuality, rapid cycling); (2) a comparison of WASH-U-KSADS to KSADS-P/L and KSADS-1986 and (3) a comparison of WASH-U-KSADS to Child Behavior Checklist (CBCL) and Teachers Report Form (TRF) data. METHODS: Data were from the first 60 bipolar (BP) and first 60 ADHD subjects of 270 consecutively ascertained cases (90 BP, 90 ADHD and 90 community controls) in the NIMH funded 'Phenomenology and Course of Pediatric Bipolarity' study. Comprehensive assessments included the WASH-U-KSADS (administered blindly to mothers and separately to children), CBCL and TRF. RESULTS: As reported elsewhere in this volume, WASH-U-KSADS data significantly differentiated BP and ADHD groups. Significant differences were also found with the parent-rated CBCL and the teacher-rated TRF, thereby providing cross-modality and cross-informant validation of the WASH-U-KSADS. Because of the close agreement with published CBCL data from another investigator, cross-site validation also occurred. LIMITATIONS: Venues for consecutive ascertainment from the lowest socioeconomic status classes were unavailable due to current health care policies. CLINICAL RELEVANCE: CBCL and TRF data separated BP from ADHD groups, largely by non-specific externalizing dimensions (e.g., hyperactivity, aggressivity). Clinically relevant differentiation by categorical mania-specific criteria (e.g., elated mood, grandiosity, racing thoughts) occurred with WASH-U-KSADS data. Both types of data are crucial for genetic and neurobiological studies.

Adolescent↗
PubMed1998

Lithium for prepubertal depressed children with family history predictors of future bipolarity: a double-blind, placebo-controlled study.

BACKGROUND: Because of negative studies of TCAs for prepubertal major depressive disorder (PMDD) and because of the potentially high switch rate of PMDD to prepubertal bipolarity (BP), it was hypothesized that lithium would be efficacious treatment for PMDD in children who also had family history (FH) predictors of future BP. METHODS: A double-blind, placebo-controlled, and pharmacokinetically dosed study of lithium for PMDD with FH predictors of future BP was performed. Random assignment was stratified by FH of BP-I or mania versus loaded/multigenerational (L/M) FH of MDD without BP-I or mania. Comprehensive assessments were done during a six week outpatient protocol that included weekly serum lithium levels. RESULTS: Mean age was 10.7+/-1.2 years; 17 subjects were randomized to active and 13 to placebo; 80% had FH of BP-I or mania (40% of parents had BP-I or mania); and 20% had FH of L/M MDD. Using both intent to treat with last observation carried forward (n = 30) and completer (n = 24) analyses, there were no significant differences on continuous or categorical measures between active and placebo groups. Mean serum lithium level was 0.99+/-0.16 mEq/l. There were no significant differences between mean total daily dose or mean serum lithium levels between responders and non-responders. LIMITATIONS: Four subjects on active drug were discontinued because of dose-limiting side effects (three were cognitive impairment). Future studies of treatment for PMDD should consider alternative drugs. CLINICAL RELEVANCE: Lithium was not significantly more efficacious than placebo for PMDD with FH predictors of future BP.

Adolescent↗
PubMed1998

Use of exogenous hormones hormones and risk of papillary thyroid cancer (Washington, United States).

OBJECTIVES: Greater incidence of thyroid cancer in women than men, particularly evident during the reproductive years, has led to the suggestion that female hormones may increase risk of this disease. We conducted a population-based case-control study in women aged 18 to 64 years in three counties of western Washington State (United States) to assess the relation of use of exogenous hormones, including oral contraceptives (OC) and hormone replacement therapy (HRT), to risk of papillary thyroid cancer. METHODS: Of 558 women with thyroid cancer of the follicular epithelium diagnosed during 1988-94 who were identified as eligible, 468 (83.9 percent) were interviewed; this analysis was restricted to women with papillary histology (n = 410). Controls (n = 574) were identified by random digit dialing, with a response proportion of 73.6 percent. Logistic regression was used to calculate odds ratios (OR) and associated 95 percent confidence intervals (CI) estimating the relative risk of papillary thyroid cancer among users of exogenous hormones. RESULTS: Among women aged 45 to 64 years, we observed no association of use of OCs or HRT with risk of papillary thyroid cancer. Among women less than 45 years of age, risk of papillary thyroid cancer was reduced in women who had ever used OCs (OR = 0.6, CI = 0.4-0.9); beyond the relation with ever-use, there was no further association with specific aspects of exposure such as estrogenic potency, latency, recency, age at first or last use, or use at the reference date. CONCLUSIONS: Our data do not support the hypothesis that use of exogenous estrogens increases the risk of female thyroid cancer.

Adolescent↗