Night-to-night variability in CPAP use over the first three months of treatment

Caries of the pits and fissures of permanent teeth continues to be a problem for children, newly erupted permanent molars being particularly at risk. Oral hygiene measures have been shown to be able to reduce the incidence of caries. The aim of this study was to compare the caries-preventive effects on newly erupted first permanent molars of a professional tooth cleaning and oral health education program (test) with a standard preventive program (control), comprising selective fissure sealing and application of topical fluorides. School Dental Service clinics of the Health Department of Western Australia, in Perth, were assigned to four test or four control clinics. Schoolchildren, mean age 6.3 +/- 0.3 (s) years with sound, newly erupted first permanent molars were included in the study (207 test, 197 control). After 12 months, 186 test and 163 control children were examined by an examiner who was 'blind' to the test or control status of the children. Caries of the first permanent molars developed in 34 test and 35 control children; the estimated risk ratio was 0.86 (95% CI 0.56, 1.30). Children in the test group had an average DFT score of 0.26 +/- 0.62 compared with 0.29 +/- 0.64 DFT in the control group (t-test, P = 0.67). The 12-month results suggest that there was no statistically significant difference between the caries-preventive effects of a professional tooth cleaning and oral health education program and a program based on selective fissure sealing and application of topical fluorides.     

Expression of cyclins D1 and E in human colon adenocarcinomas

Cyclins D1 and E play critical roles in the progression of cells through the G1 phase of the cell cycle. Amplification and/or overexpression of the cyclin D1 gene and aberrant expression of cyclin E have been described in several forms of human cancer. In the present study, we examined the expression of these two genes by Western, Northern and Southern blot analyses in a series of primary human colon carcinomas of various stages and degrees of differentiation and in paired adjacent normal mucosa samples, and also in a series of human colon carcinoma cell lines. About 50% of the colon carcinomas displayed a two to five fold increase in the expression of cyclin D1 mRNA and protein, when compared with the paired normal mucosa samples. Six out of eight carcinomas examined showed a four to nine fold increase in cyclin E mRNA and about 50% of the carcinomas displayed a two to three fold increase in cyclin E protein. Low molecular weight cyclin E-related proteins were observed in four out of ten carcinomas. These changes in cyclins D1 and E occurred in both early and late stage tumors. Three of the six cell lines examined displayed a high expression of cyclin D1 mRNA and protein. A very high level of cyclin E mRNA expression was seen in HCT116 cells and this was associated with the presence of low molecular weight cyclin E-related proteins. None of the primary colon carcinomas nor the six cell lines examined displayed amplification of either the cyclin D1 or cyclin E genes. Thus, an aberrant expression of both cyclins D1 and E occurs in a significant fraction of human colon carcinomas.     

Molecular epidemiology of rabies epizootics in Texas

Glucocorticoids are potent osteopenic agents, producing negative calcium and bone balance via actions at many sites. The most significant adverse effects of glucocorticoid drugs on the skeleton are probably a direct inhibition of matrix synthesis by the osteoblast, reductions in calcium absorption in both the gut and the renal tubule, and the production of hypogonadism, particularly in men. Reductions in bone density of 10-40% result, the loss being more marked in trabecular bone and in patients receiving a high cumulative dose of the steroid. Fractures occur in about 30% of individuals who take these drugs for an average of 5 years. Bone loss is reversible when glucocorticoid treatment is withdrawn. Bone density can also be increased by sex hormone replacement in those with demonstrable deficiency, by bisphosphonates, and possibly by vitamin D metabolites. All patients treated with glucocorticoids for more than 6 months should be considered for bone densitometry and be offered appropriate drug treatment if values are towards the lower end of the young normal range or if there is already evidence of fractures occurring after minimal trauma. With this approach, the significant morbidity associated with steroid osteoporosis might be substantially avoided.     

Exacerbation of inflammation-associated colonic injury in rat through inhibition of cyclooxygenase-2

Cyclooxygenase type 1 is constitutively expressed and accounts for synthesis of prostaglandins in the normal gastrointestinal tract. Cyclooxygenase-2 is expressed at sites of inflammation. Selective inhibitors of cyclooxygenase-2 have been suggested to spare gastrointestinal prostaglandin synthesis, and therefore lack the ulcerogenic effects associated with standard nonsteroidal antiinflammatory drugs. However, the effects of cyclooxygenase-2 inhibitors on inflamed gastrointestinal mucosa have not been examined. We examined cyclooxygenase-2 mRNA and protein expression before and after induction of colitis in the rat, the contribution of cyclooxygenase-2 to colonic prostaglandin synthesis during colitis and the effects of selective inhibitors of cyclooxygenase-2 on colonic injury in this model. Cyclooxygenase-2 mRNA expression increased three to sixfold during the period 24 h to 1 wk after induction of colitis, with marked increases in cyclooxygenase-2 protein expression in the lamina propria and muscularis of the colon during colitis. Cyclooxygenase-1 expression (mRNA and protein) was not affected by the induction of colitis. The prostaglandins produced during colitis were largely derived from cyclooxygenase-2. Treatment with selective cyclooxygenase-2 inhibitors resulted in exacerbation of colitis, with perforation occurring when the compounds were administered for a week. These studies demonstrate that suppression of cyclooxygenase-2 can result in exacerbation of inflammation-associated colonic injury.     

Transient loss of dopamine autoreceptor control in the presence of highly potent dopamine agonists

The concentrations of endogenous ligands generally remain in a bounded range around a basal level, a manifestation of control. The dopaminergic system is an excellent example of a control system in which a negative feedback signal is associated with receptor occupancy of a D2-like dopamine autoreceptor. A consequence of the control theory is that autoreceptor occupancy by an agonist results in dopamine levels below the basal, whereas similar stimulation by a dopamine competitive antagonist results in an increase of dopamine to levels above the basal. These consequences of control theory were tested and verified in the rat striatum by infusing graded doses of either the agonist, quinpirole, or the antagonist, sulpiride, into the rat striatum via a microdialysis probe and sampling dopamine and metabolite levels at various times after the start of infusion. Control was maintained even at the very highest doses of these compounds, i.e., striatal dopamine concentration rose in response to the antagonist and fell in response to the agonist. In contrast, administration of each of two high affinity dopamine agonists, 7-OH-DPAT and PPHT showed dose-dependent control only up to certain doses. Above these doses the dopamine concentration actually increased to levels well above basal, an indication of loss of control. These findings suggest that the control of this endogenous ligand does not extend to the very highest levels of autoreceptor occupancy.     

In vitro and in vivo studies of benzisoquinoline ligands for the brain synaptic vesicle monoamine transporter

Tetrabenazine is a high-affinity inhibitor of the vesicular monoamine transporter in mammalian brain. As part of a program to develop in vivo imaging agents for these transporters in human brain, a series of 2-alkylated dihydrotetrabenazine ligands was synthesized and evaluated in vitro and in vivo for binding to the brain vesicular monoamine transporter. Additions of organometallic reagents to tetrabenazine produced 2-methyl, 2-ethyl, 2-n-propyl, 2-isopropyl, and 2-isobutyl derivatives of dihydrotetrabenazine. The stereochemistry and conformation of the addition products were thoroughly verified by two-dimensional NMR techniques. All of these alkyl derivatives displayed in vitro affinity for the vesicular monoamine transporter binding site in rat brain using competitive assays with the radioligand [3H]methoxytetrabenazine. Except for the isopropyl derivative, all compounds when tested at 10 mg/kg iv showed an ability to inhibit in vivo accumulation of the radioligand [11C]methoxytetrabenazine in the mouse brain striatum. Derivatives with small alkyl groups (methyl, ethyl) were more effective than those with large groups (propyl, isobutyl). These studies suggest that large groups in the 2-position of the benzisoquinoline structure will significantly diminish both in vitro and in vivo binding of these compounds to the vesicular monoamine transporter.     

A chromosome 14q11/TCR alpha/delta specific yeast artificial chromosome improves the detection rate and characterization of chromosome abnormalities in T-lymphoproliferative disorders

The rate of detection of chromosome abnormalities in T-cell proliferations is lower than that observed in B-cell malignancies. The former frequently involve the TCR alpha/delta locus at chromosome band 14q11. We have identified a YAC encompassing 70% of the TCR alpha/delta locus, which has been used as a fluorescence in situ hybridization probe to detect chromosome rearrangements involving 14q11, both at metaphase and within interphase nuclei, in patients with a variety of T-lymphoproliferative disorders. Its use allowed detection of previously unsuspected TCR alpha/delta rearrangements in 4/13 (30%) immature T-lineage acute leukemias, including two t(10;14) and 2 minor inversion 14s. It also clarified interpretation of complex chromosome 14 abnormalities in mature T-cell proliferations (T-prolymphocytic leukemia and ataxia telangiectasia). Use of this probe will aid the detection and characterization of abnormalities involving the TCR alpha/delta locus, particularly in cases with normal or complex karyotypes and in those proliferations for which mitoses are difficult to obtain.     

Induction of apoptosis in HL-60 human promyelocytic leukemia cells by adenosine A(3) receptor agonists

The effects of adenosine (ADO) analogs on cells of the human promyelocytic HL-60 line were examined. ADO A(3) receptor agonists, N(6)-(3-iodobenzyl)adenosine-5'-N-methylcarboxamide (IB-MECA, 30-60 microM) and 2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide (CI-IB-MECA, 10-30 microM) induced apoptotic cell death. In contrast, neither an A(1)/A(2) antagonist (XAC) nor other selective ADO receptor agonists (CPA, NECA and CGS21680) induced apoptosis at concentrations of <30 microM. Both IB-MECA and CI-IB-MECA significantly induced Ca(2+) release from intracellular Ca(2+) pools followed by Ca(2+) influx, suggesting the presence of phospholipase C-coupled ADO A(3) receptors on HL-60 cells. This was further supported by the presence of mRNA of ADO A3 receptor in the cells. These results suggest that activation of ADO A(3) receptors is responsible for the ADO-induced apoptosis in HL-60 cells and could be of potential therapeutic value in the treatment of leukemia.     

Inhibition of nicotinic responses of bovine adrenal chromaffin cells by the protein kinase C inhibitor, Ro 31-8220

1. The effects of the protein kinase C inhibitor, Ro 31-8220, on the responses of cultured bovine adrenal chromaffin cells to nicotine, phorbol 12, 13-dibutyrate (PDBu) and K+ have been investigated. 2. Tyrosine hydroxylase activity was measured in situ in intact cells by measuring 14CO2 evolved following the hydroxylation and rapid decarboxylation of [14C]-tyrosine offered to the cells. Secretion of endogenous adrenaline and noradrenaline was measured by use of h.p.l.c. with electrochemical detection. Cyclic AMP levels were measured in cell extracts by RIA. 3. Ro 31-8220 produced a concentration-dependent inhibition of 300 nM PDBu-stimulated tyrosine hydroxylase activity with an IC50 of < 2 microM and complete inhibition at 10 microM. It had no effect on the responses to forskolin. 4. Ro 31-8220 produced a concentration-dependent inhibition of 5 microM nicotine-stimulated tyrosine hydroxylase activity, adrenaline and noradrenaline secretion and cellular cyclic AMP levels, with an IC50 of about 3 microM and complete inhibition by 10 microM. At concentrations up to 10 microM, Ro 31-8220 had little or no effect on the corresponding responses to 50 mm K+. 5. A structural analogue of Ro 31-8220, bisindolylmaleimide V, that lacks activity as a protein kinase C inhibitor, had no effect up to 10 microM on PDBu-stimulated tyrosine hydroxylase activity or on nicotine-stimulated cyclic AMP levels or noradrenaline secretion and only marginal inhibitory effects on nicotine-stimulated tyrosine hydroxylase activity and adrenaline secretion. 6. A structurally related protein kinase C inhibitor, bisindolylmaleimide I, inhibited PDBu-stimulated tyrosine hydroxylase activity with an IC50 of < 1 microM and complete inhibition by 3 microM, but had essentially no effect on nicotine stimulated tyrosine hydroxylase activity or catecholamine secretion. 7. The results suggest that Ro 31-8220 is not only a protein kinase C inhibitor but is also a potent inhibitor of nicotinic receptor responses in adrenal chromaffin cells by a mechanism unrelated to protein kinase C inhibition. The results are consistent with Ro 31-8220 being a nicotinic receptor antagonist.