Search PubMed⌕ Search

Biomedical subjects

N G Clarke

Publications and source records attributed to N G Clarke.

At least 37 records · Page 2Linked to original sources
PubMed1984

Bruxing patterns in man during sleep.

Nocturnal clenching was monitored using a dedicated microprocessor, appropriate EMG amplification and digitisation. The hardware was located at the subject's bedside and the software provided for the real time recording of clenching bruxism, duration of the episode and the severity in electronic values. Forced clenches before retiring and on arousing provided maximal baseline data against which to compare the severity of sleeping clenches. All ten subjects tested were found to brux and two used intensities of effort while asleep that exceeded their maximal conscious clenches.

Adult↗
PubMed1984

Distribution of nocturnal bruxing patterns in man.

The distribution of nocturnal bruxing patterns in nine subjects was recorded and interpreted in accordance with current concepts of sleep physiology. Few bruxing events were seen in the first 2 h of sleep but peak periods were identified during the night. The findings suggested that bruxism and REM sleep were closely associated and pointed towards a central aetiology for bruxing activity.

Bruxism↗
PubMed1983

Relationship between infant death and maternal age. Comparison of sudden infant death incidence with other causes of infant mortality.

The high incidence of sudden infant death syndrome in infants born to teenage mothers prompted us to search for epidemiologic clues that might relate to SIDS causation. The death rate for SIDS was compared with that of other major causes of infant mortality in two maternal age groups (younger than 20 years and 30 to 34 years). In the neonatal period, a significantly greater overall mortality occurred in infants born to the younger mothers. This difference was primarily related to an excess of low-birth-weight infants dying from diseases of early infancy. "Weight-specific" mortality, however, was similar for the two groups. In the postneonatal period, when most SIDS occurs, the incidence was 5.2 per 1000 among infants of teenage mothers, compared with 1.0 in infants of the older mothers. A similar maternal-age-related incidence was observed for death from infections, accidents, and "other causes." By contrast, death from congenital anomalies was unrelated to maternal age in both periods. We conclude that many postneonatal deaths are influenced by environmental factors, including the age and maturity of the mother.

Adolescent↗
PubMed1983

Utilization of dental services and its relation to the periodontal status in a group of South Australian employees.

The pattern of dental service utilization, the perception of periodontal disease, and the oral hygiene habits among 642 industrial employees were evaluated using a self-administered questionnaire against background variables of age, sex, and socioeconomic strata. Of the study population, 50.5% had their most recent dental visit within the previous 12 months and 42.5% claimed to seek regular check ups. There was no significant association between time intervals since the last dental visit and age, sex, occupation, income or education. Regular visits were made more often by subjects in the higher occupation and income level. Multivariate analyses of the number of missing teeth simultaneously considering age, sex, socioeconomic level, regularity and frequency of dental visits revealed that except for age and sex, no other factors were significant. The most common reason for not seeing a dentist in the previous 12 months was an assumption that "nothing was wrong". A large majority of the group surveyed were unaware of the presence of periodontal disease or the need for its treatment, despite the high prevalence in all subgroups. Periodontal status was not significantly associated with sex, socioeconomic levels, regularity of frequency of dental visits, but there was a significant regression on age. The study population's pattern of service utilization was found to be similar to that reported for the general population, and it was anticipated that the hygiene habits of the group was representative of the total community. If that assumption is true the high prevalence of periodontal disease of the study population probably exists in the general community.

Adolescent↗
PubMed1983

Indochinese refugee fertility rates and pregnancy risk factors, Oregon.

Matching 471 Oregon birth certificates with official Indochinese arrival lists reveals a fertility rate of 126.7, 1.8 times the US rate of 68.5. Greater maternal and infant risk rates were noted, particularly for Hmong. Data indicate improvements in obtaining prenatal care and in reducing the number of low birth weight infants for refugees who have resided in the US three or more months: however, the improvements appear to be reversed after 12 months of US residency.

Adolescent↗
PubMed1982

Periodontal status in a South Australian industrial population.

The periodontal status of 680 industrial employees in Adelaide, South Australia, was assessed in a descriptive epidemiologic survey. Full mouth recording using the recently proposed WHO 'TRS 621' survey method (14) was used by two calibrated examiners. Periodontal disease in this population was highly prevalent and typically of moderate severity. Only 4.2% of the subjects were free from any signs of periodontal disease. In 11.1% the disease manifestation was confined to reversible gingivitis. Mild periodontal disease was evident in approximately 60% and severe disease in 25% of the population. The major treatment requirement in all age groups could be categorized as "simple periodontal treatment" manageable by non specialist dental resources. More than 90% of pockets detected occurred interproximally. Some features of the proposed WHO 'TRS 621' survey methodology are discussed.

Adolescent↗
PubMed1982

Rational periodontal therapy by papillectomy.

Successful periodontal therapy provided by the clinician is largely dependent on the removal of supra- and subgingival calculus and on the careful preparation of root surfaces to remove trapped endotoxin. A suitable environment for the reattachment of epithelial cells and fibroblasts results. The papillectomy technique provides good visual and instrumental access to the interproximal tooth surfaces, and allows optimal preparation of cemental surfaces without the necessity of a full surgical procedure.

Dental Scaling↗
PubMed1981

Alkaline O leads to N-transacylation. A new method for the quantitative deacylation of phospholipids.

1. Quantitative O-deacylation of phospholipids has been achieved by incubation with a reagent containing monomethylamine, methanol and water. The reaction is primarily an O leads to N-transacylation with N-methyl fatty acid amides being formed. 2. The reagent can be removed easily by volatilization and under defined conditions no secondary decomposition of the phosphorus-containing deacylation products occurs. 3. The water-soluble phosphorus compounds derived by deacylation of mammalian tissue O-diacylated phospholipids have been completely separated by a single-dimensional paper ionophoresis with a volatile pH9 buffer. 4. The O-deacylated alkyl and alkenyl phospholipids have been examined by t.l.c. before and after catalytic hydrolysis with Hg2+. 5. A complete analysis of rat brain phospholipids by the above methods agrees closely with that obtained by other procedures.

Acylation↗
PubMed1981

The effects of intra-arterial epinephrine and nicotine on gingival circulation.

The purpose of this study was to test the hypothesis that acute necrotizing ulcerative gingivitis (ANUG) was the result of ischemia resulting from three predisposing factors. Vascular stasis, stress, and smoking were said to combine and induce severe vascular constriction at the end arterial locations of the gingivae, resulting in necrosis of the part. The experimental animal used was the rabbit; clinical doses of epinephrine and nicotine were infused intraarterially and the gingival circulation was monitored by the heat-diffusion principle. It was found that the chemicals caused a severe reduction in flow rates in spite of greatly increased pressure within the system. The finding supports the hypothesis that ischemia could play an important role in the initiation of ANUG.

Animals↗
PubMed1981

The effect of locally released oxygen on the development of plaque and gingivitis in man.

An experimental gingivitis study was designed to test the effect of a 5-min twice daily oxygen application on the development of plaque and onset of gingivitis. A method for the local application of medical grade oxygen to the upper anterior teeth was developed, with the lower anterior teeth used as controls. Fourteen periodontally healthy dental students of average age 21.9 years participated in the study. There was no significant effect of oxygen on plaque formation, crevicular fluid flow, or the number of gingival bleeding sites. Experimental and control gingival segments exhibited bleeding on probing at an average of 6.6 days after cessation of mechanical plaque control, much earlier than reported in other experimental gingivitis studies.

Adult↗
PubMed1980

Complex lipids of a lipolytic and general-fatty-acid-requiring Butyrivibrio sp. isolated from the ovine rumen.

The complex lipids of the naturally-occurring general-fatty-acid-auxotroph Butyrivibrio S2 [Hazlewood & Dawson (1979) J. Gen. Microbiol. 112, 15-27] grown with palmitic acid as sole fatty-acid supplement have been investigated and some have been isolated in a state of purity and analysed. The majority are phospholipids (84%) and many contain galactose. They typically possess few esterified long-chain fatty-acid residues (C16:0), but are rich in esterified butyric acid and C16-alkenyl groups. Most of the phosphorus-containing lipids, including the two major lipids of the organism, contain esterified diabolic acid, a long-chain vicinal dimethyl-substituted dicarboxylic acid [Klein, Hazlewood, Kemp & Dawson (1979) Biochem. J. 183, 691-700] in definite stoichiometric relationship to phosphorus. No phosphatidylglycerol was present, but its monobutyroyl ester was detected as a minor component. Galactofuranosyldiacylglycerol (plasmalogen) and its monobutyroyl ester, cetyl alcohol and diacylglycerol were also identified.

Chemical Phenomena↗
PubMed1980

Structure of diabolic acid-containing phospholipids isolated from Butyrivibrio sp.

The structures of the diabolic acid-containing phospholipids of Buryrivibrio S2 grown in the presence of palmitic acid have been investigated. Generally they consist of two conventional bacterial phospholipid or galactolipid structures linked by esterification through a single diabolic acid residue. The main lipid consists of the butyroyl ester of sn-1-alkenylglycero-3-phospho-1'-sn-glycerol joined in this way to the butyroyl ester of sn-1-alkenyl-3-galactosylglycerol by esterification of the vacant 2-hydroxy groups of the alkenyl-substituted glycerol molecules. A lipid that possess a palmitoyl group rather than one of the butyroyl groups of the latter structure has also been detected. The lipid occurring in the second highest concentration consists of two molecules of sn-1-alkenylglycero-3-phospho-sn-1'-glycerol butyroyl ester linked through diabolic acid in a similar manner to the main lipid. Other lipids with the latter structure either minus a butyroyl group or with palmitoyl group, instead of one of the buryroyl groups, exist as minor components.

Chemical Phenomena↗
PubMed1980

Glycerol vic-cyclic phosphate in rat tissues.

On labelling rat tissues with 32P, a radioactive phosphate ester can be isolated with the same chromatographic and ionophoretic properties and susceptibility towards a specific phosphodiesterase and acid as glycerol vic-cyclic phosphate. By comparison with precursor phosphoglycero-derivatives in the same tissues it is calculated that the concentration in liver, kidney and brain is in the order of 0.7--4.0 nmol/g wet wt.

Animals↗
PubMed1977

Has small-scale audio-visual dental health education a viable future?

The achievement of an adequate oral hygiene status in large groups of people remains an unfulfilled objective of the dental profession. In this study an attempt was made to motivate 180 pregnant women by showing them a tape-slide program. The subjects were randomly allocated into four statistically equal experimental groups. Two examiners, who were calibrated before commencement of the survey, measured Gingival and Plaque Indices of each subject and a questionnaire was used to assess the educational potential of the tape-slide sequence over a period of 4 weeks. There was a 100% incidence of gingivitis in the study population. Those women who viewed the tape-slide program in addition to being dentally examined, achieved the greatest reduction in their GI and retained the most information. The tape-slide sequence alone did not initiate a satisfactory degree of behavioral change; similar studies have also had discouraging results and it would appear that individual attention and motivation is the only sure way to date of achieving adequate personal plaque control.

Adult↗