Biomedical subjects
D W Smith
Publications and source records attributed to D W Smith.
Teachers' use of health curricula: implementation of growing healthy, project SMART, and the teenage health teaching modules.
This quasi-experimental study assessed impact of factors associated with classroom implementation of health curricula by North Carolina teachers. School representatives selected and implemented one of three tobacco prevention curricula--Project SMART, Growing Healthy, or the Teenage Health Teaching Modules--in either sixth or seventh grades. Prior to implementation, experimental teachers and administrators received extensive curricula training. Implementation data were collected through teacher completed checksheets and classroom observations for two time periods--initial implementation (n = 69) and maintained implementation (n = 136). While training was associated significantly with whether teachers implemented a curriculum (p < .05), other factors also were important. Variables outside of teachers' direct control, such as supportive administrators, context in which health instruction is taught, and turbulence, affected quantity and quality of curricular implementation.
Damage to cochlear efferents following AF64A intoxication.
Damage to cochlear efferents in chinchillas was assessed using transmission electron microscopy following unilateral treatment with the cholinotoxin ethylcholine mustard aziridinium ion (AF64A). AF64A was diluted in artificial perilymph to concentrations ranging from 0.5 to 100 microM. Survival times ranged from 1 to 12 weeks. At concentrations above 10 microM, widespread damage was noted to efferent fibers within the inner spiral bundle (ISB), tunnel spiral bundle (TSB), tunnel radial fibers (TRF) and efferent terminals at the base of OHCs. This damage included degeneration of fibers and terminals, delamination of mitochondria, vacuolization, and loss of cell membrane. However, at high concentrations, non-specific damage was also noted as thinnings or discontinuities of the membrane of OHCs and afferent fibers. At concentrations between 3 and 10 microM, selective damage was observed to efferent fibers within the ISB, TSB, TRF, and to terminals at the base of the OHCs, with all other structures appearing normal. At concentrations of 0.5 and 1 microM, damage was limited to efferent fibers within the TSB and ISB below the inner hair cells. In general, insult was greatest to middle- and basal-turn efferents, and longer survival times did not produce greater damage to, or loss of, efferents. These data suggest that at low concentrations, AF64A produces a partial yet selective degeneration of cochlear efferents within both the medial and lateral tracts, and that at the lowest concentrations used in these studies, AF64A produces a preferential insult on lateral olivocochlear efferents.
State rate regulation and inpatient mortality rates.
Most research on hospital rate regulation has focused on costs, but concern about its consequences for quality of care, particularly mortality rates, has also been raised. In this study mortality rates and standardized mortality ratios (SMR) were computed to estimate any effect on quality, using data about Medicare beneficiaries hospitalized during 1986. Regulated states had lower SMRs for both patients and the general population than unregulated states and admitted significantly fewer patients. We found no basis for concluding that rate regulation is adversely related to patient mortality or population mortality, despite lower admission rates.
Data about mortality.
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In vivo specificity of EcoRI DNA methyltransferase.
The EcoRI adenine DNA methyltransferase forms part of a bacterial restriction/modification system; the methyltransferase modifies the second adenine within the canonical site GAATTC, thereby preventing the EcoRI endonuclease from cleaving this site. We show that five noncanonical EcoRI sites (TAATTC, CAATTC, GTATTC, GGATTC and GAGTTC) are not methylated in vivo under conditions when the canonical site is methylated. Only when the methyltransferase is overexpressed is partial in vivo methylation of the five sites detected. Our results suggest that the methyltransferase does not protect host DNA against potential endonuclease-mediated cleavage at noncanonical sites. Our related in vitro analysis of the methyltransferase reveals a low level of sequence-discrimination. We propose that the high in vivo specificity may be due to the active removal of methylated sequences by DNA repair enzymes (J. Bacteriology (1987), 169 3243-3250).
A1 neurons and excitatory amino acid receptors in rat caudal medulla mediate vagal excitation of supraoptic vasopressin cells.
Extracellular recordings from the supraoptic nucleus of the rat established that vasopressinergic neurosecretory cells were excited by stimulation of cervical but not abdominal vagal afferents. This response was absent or significantly attenuated after microinjection of gamma-aminobutyric acid into a region of the caudal medulla known to contain the A1 noradrenaline cell group. Consistent with the possible involvement of the A1 group, vagal stimulation approximately doubled the frequency of proto-oncogene expression in A1 noradrenaline neurons, as indicated by the occurrence of nuclear Fos-like immunoreactivity in tyrosine hydroxylase-positive neurons of the caudal ventrolateral medulla. Finally, A1 region microinjection of either the N-methyl-D-aspartic acid (NMDA) receptor antagonist DL-2-amino-5-phosphonovaleric acid (APV), or the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), significantly reduced vasopressin cell responses to vagal stimulation. These findings suggest that: (i) the A1 group is an essential component in a pathway which relays facilitatory vagal input of cardiopulmonary origin to neurosecretory vasopressin cells, and (ii) the activation of A1 neurons in this pathway involves both NMDA and non-NMDA excitatory amino acid receptors, an observation consistent with an input to A1 cells which generates 'mixed' excitatory postsynaptic potentials.
Cofactor and DNA interactions in EcoRI DNA methyltransferase. Fluorescence spectroscopy and phenylalanine replacement for tryptophan 183.
EcoRI DNA methyltransferase contains tryptophans at positions 183 and 225. Tryptophan 225 is adjacent to residues previously implicated in S-adenosylmethionine (AdoMet) binding and to cysteine 223, previously shown to be the site of N-ethyl maleimide-mediated inactivation of the enzyme (Reich, N. O., and Everett, E. (1990) J. Biol. Chem. 265, 8929-8934; Everett, E. A., Falick, A. M., and Reich, N. O. (1990) J. Biol. Chem. 265, 17713-17719). The fluorescence spectra of the wild-type enzyme is centered at 338 nm indicating partial tryptophan solvent accessibility. Substitution of tryptophan 183 with phenylalanine results in a 45% drop in fluorescence intensity, but no shift in lambda max. DNA binding to the wild-type methyltransferase caused an increase in the fluorescence intensity, while binding to the tryptophan 183 mutant had a quenching effect, suggesting that DNA binding induces a conformational change near both tryptophans. Binding of AdoMet and various AdoMet analogs to the wild-type methyltransferase results in no change in the fluorescence spectrum when excitation occurs at 295 nm, suggesting that no conformational change occurs, and AdoMet does not interact with either tryptophan. In contrast, quenching was observed when excitation occurred at 280 nm, suggesting that AdoMet and its analogs may be quenching tyrosine to tryptophan energy transfer. Protein-ligand complexes were titrated with acrylamide, and the data also implicate conformational changes upon DNA binding but not upon AdoMet binding, consistent with previous limited proteolysis results (Reich, N. O., Maegley, K. A., Shoemaker, D.D., and Everett, E. (1991) Biochemistry 30, 2940-2946).
Antiviral agents: problems and promises.
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DNA replication, the bacterial cell cycle, and cell growth.
The coupling of replication to the cell cycle and cell growth involves events that occur at oriC. Immediately after initiation, there is an eclipse phase during which reinitiation from the newly synthesized origins is prevented. GATC sites in oriC remain in a hemimethylated state longer than other sites because of their association with the outer membrane, which prevents DnaA from binding and activating additional rounds of initiation. After the origins are methylated and released from the outer membrane, the concentration of newly synthesized DnaA and the activation of oriC by transcription from the nearby mioC and gid promoters determine when the next rounds of replication initiate. If growth rate is reduced, the synthesis of (p)ppGpp will increase, and this will lead to a decrease in dnaA, mioC, and gid transcription. On the other hand, if growth rate is increased by access to a tasty meal, synthesis of (p)ppGpp will decrease, expression of dnaA, mioC, and gid genes will increase, and a shortening of the interinitiation time will result. The participation of all these control features ensures rapid and precise coordination of DNA replication with cell growth.
A survey of oral and maxillofacial surgeons concerning their knowledge, beliefs, attitudes, and behavior relative to parameters of care.
In December 1990, a survey was sent to 1,296 randomly selected members of the American Association of Oral and Maxillofacial Surgeons (AAOMS) to determine their previous experience with standards and criteria of care, their type of practice, the educational methods that influence their professional decisions, and their attitudes about the development and use of parameters of care. A 55.7% response was obtained. This article reports the results of this survey. The average age of responding surgeons was 45 years and they had been in practice an average of 15 years. The majority were in private practice, had hospital staff privileges, worked between 31 and 55 hours per week, spent 90% of their working week in direct patient care, and devoted an average of 9.16 hours per month to professional affairs outside of their practice. Forty-two percent (42%) of the practitioners were in solo practice, whereas 50% practiced in groups. Surgeons concentrated 65% of their patient care time on dentoalveolar surgery and a significant number planned increases in practice activity in implant, orthognathic, and temporomandibular joint surgery. They learned new clinical skills in various ways, there being a difference between the most convenient and effective methods of learning. A majority of surgeons had been involved with quality assurance activities in the past 5 years. They were predominantly favorable to parameters now and when they first learned about them, but few thought they had a clear understanding about how parameters of care would be used.(ABSTRACT TRUNCATED AT 250 WORDS)
Comparison of apical leakage in teeth obturated with a polyamide varnish or zinc oxide and eugenol cement using lateral condensation.
The sealing ability of copal varnish has been investigated when used as an adjunct in restorative procedures, retrofilling procedures, and dontic obturation procedures. Barrier, a polyamide-type polymer cavity varnish, has been compared with copal varnishes in restorative dentistry. This investigation compared the apical sealing properties of a zinc oxide and eugenol sealer (Roth) with a polyamide varnish (Barrier). Twenty-four teeth were instrumented and divided into two groups, one obturated with gutta-percha and Roth sealer and one with gutta-percha and Barrier, using submersion in methylene blue dye to demonstrate apical leakage. Roth sealer exhibited less dye penetration than Barrier when used as an endodontic sealant (p < 0.02).
RecA protein of Escherichia coli and chromosome partitioning.
Escherichia coli cells deficient in RecA protein frequently contain an abnormal number of chromosomes after completion of ongoing rounds of DNA replication. This suggests that RecA protein may be required for correct timing of initiation of DNA replication; however, we show here that initiation of DNA replication is properly timed in recA mutants. We also find that more than 10% of recA mutant cells contain no DNA. These anucleate cells appear to arise from partitioning of all the DNA into one daughter cell and no DNA into the other daughter cell. Based on these and previously published results, we propose that RecA protein is required for equal partitioning of chromosomes into the two daughter cells.
The longevity of Growing Healthy: an analysis of the eight original sites implementing the School Health Curriculum Project.
The status of the Growing Healthy curriculum (School Health Curriculum Project [SHCP]) was examined in the eight sites selected in 1969 by the National Clearinghouse on Smoking and Health to receive funded training and implementation support. A contact person from each site completed and returned a questionnaire pertaining to the district's continued implementation (institutionalization) of the SHCP. Most districts had not continued to implement the program. Reasons for discontinuation included loss of the "program champion" and insufficient administrative leadership. Districts continuing to implement the program generally were smaller in size, and employed a part-time coordinator for the SHCP. Recommendations for institutionalizing future instruction programs include identifying replacement program coordinators and other administrators to ensure continuity and support for the program over time, and conducting process and impact evaluations on program effects.
Growth characteristics of recent sputum isolates of Mycobacterium tuberculosis in guinea pigs infected by the respiratory route.
The consideration of virulence must distinguish between infectivity and the ability to cause progressive disease once the infection is established. Several investigators have reported the presence of naturally occurring isolates which differ in virulence for guinea pigs. Isolates from south India which differed with respect to gross disease and number of bacilli recovered from spleen after an intramuscular infection also differed in their efficiencies to initiate an infection, once inhaled and retained. Also, this difference was correlated with differences in the rate of multiplication at the site of implantation and rate of multiplication at sites of hematogenous seeding, as well as the extent of hematogenous seeding. The number of metastatic foci was identified as a quantitative measure of hematogenous seeding, which was not confounded by the rate of multiplication of bacilli. Even allowing for the fourfold-reduced efficiency of low-virulence tubercle bacilli to produce a lesion, this measure clearly revealed a significantly reduced ability of the low-virulence tubercle bacilli to disseminate via the bloodstream.
Localization of alg, opr, phn, pho, 4.5S RNA, 6S RNA, tox, trp, and xcp genes, rrn operons, and the chromosomal origin on the physical genome map of Pseudomonas aeruginosa PAO.
The genes encoding the rrn operons, the 4.5S and 6S RNAs, elements of protein secretion, and outer membrane proteins F and I, and regulatory as well as structural genes for exotoxin A, alkaline phosphatase, and alginate and tryptophan biosynthesis, were assigned on the SpeI/DpnI macrorestriction map of the Pseudomonas aeruginosa PAO chromosome. The zero point of the map was relocated to the chromosomal origin of replication.
Escherichia coli cells lacking methylation-blocking factor (leucine-responsive regulatory protein) have precise timing of initiation of DNA replication in the cell cycle.
A protein that is required for specific methylation inhibition of two GATC sites in the papBA pilin promoter region, known as methylation-blocking factor (Mbf) and recently shown to be identical to the leucine-responsive regulatory protein (Lrp), is not responsible for the delayed methylation at oriC implicated in an eclipse period following initiation of DNA replication. Cells containing a transposon mutation within the mbf (lrp) gene initiate DNA replication at the correct time during the cell cycle, whereas cells with increased amounts of the Dam methyltransferase initiate DNA replication randomly throughout the cell cycle.
The effect of alcohol on emotional response to a social stressor.
Social drinkers were administered either an alcoholic, placebo or no-alcohol control beverage. Subjects were next informed that they were to give a self-disclosing speech about their body and physical appearance. Subjects' heart rate and videotapes of their facial expression were recorded during this instruction. Facial reactions to the stressor were analyzed using a system based on the Maximally Discriminative Facial Coding System (Izard, 1979). Subjects who were intoxicated showed significantly less negative emotion, as measured by the facial expression analysis, than those subjects consuming either the control or placebo beverage. We attribute this effect of alcohol to its actions on subjects' appraisal of anxiety-inducing information.