Electrical stimulation of teeth with a pulp tester in the cat

Abstract – Responses of 241 pulpal and 219 non-pulpal nerve fibers to monopolar electrical stimulation were studied in 12 anesthetized cats. Stimulation was carried out with a clinically used pulp tester (Bofors PT-1®) to the intact crown of mandibular canine tooth and to the surrounding soft tissues not further than 1.5 cm from the tooth. Action potentials from nerve preparations containing either a single or a few functional fibers were recorded. The minimum current strength needed to excite the axon ("threshold current") was determined. The purpose of the study was to investigate how specifically monopolar electrical stimulation of the tooth crown excites the nerves of the dental pulp and to what extent fibers of surrounding tissue are affected. The mean threshold of excitation of the pulpal nerve fibers was 28.3 μA ± 1.4 s.e.m. Of 219 non-pulpal fibers sensitive to mechanical stimulation of the tooth and the surrounding area, only 10 fibers of periodontal origin were caused to discharge due to electrical stimulation applied to the tooth crown. Their mean threshold was 96.0 μA± 5.2 s.e.m. When the receptive fields of 50 mechanoreceptor units in soft tissue were stimulated electrically, only nine responded to current values less than 125 μA. It seems that pulp nerve fibers respond to very much lower current intensities than non-pulpal fibers, when monopolar electrical stimulation is applied to the tooth crown. The risk of activation of non-pulpal nerves in pulp tests seems to be minimal supposing that reasonable current strength is used.     

Plasma Histamine and Serum Pepsinogen I Concentrations in Chronic Myelogenous Leukaemia

ABSTRACT A male patient with multiple gastroduodenal ulcers and gastric hypersecretion due to hyperhistaminaemia associated with extreme basophilia occurring in chronic myelogenous leukaemia (CML) is described. In addition, plasma histamine levels and serum pepsinogen I concentrations, reflecting gastric acid secretion, were studied in 18 CML patients. As compared to controls, plasma histamine levels were clearly increased in CML patients and correlated well with the basophil count. Serum pepsinogen I concentrations were normal in 14 out of 17 cases and did not correlate with plasma histamine levels. This absence of a direct relation between plasma histamine concentrations and serum pepsinogen I levels suggests that a high concentration of circulating histamine does not inevitably lead to increased gastric acid secretion. This offers one explanation of the fact that, in spite of the frequent occurrence of basophilia and hyperhistaminaemia in CML, ulcerogenic diathesis is quite rare in this disease and complicates only cases with extreme basophilia.     

MATRIX METALLOPROTEINASE-2 (72 kD TYPE IV COLLAGENASE) EXPRESSION OCCURS IN THE EARLY STAGE OF HUMAN MELANOCYTIC TUMOUR PROGRESSION AND MAY HAVE PROGNOSTIC VALUE

Matrix metalloproteinase-2 (MMP-2), a member of the matrix metalloproteinase family, participates in degradation of the pericellular and extracellular matrix during neoplastic growth and metastasis. Experimental data have substantiated its role in melanoma invasion, but there is no information at present concerning its expression in histological specimens from human melanocytic tumours. This study describes the occurrence and immunolocalization of MMP-2 in human melanocytic lesions, defining distinct steps in melanoma progression. Paraffin-embedded sections from 118 melanocytic lesions were immunostained using a specific antibody to 72 kD type IV collagenase. The material included 34 common naevocellular naevi, 14 dysplastic naevi, 21 in situ melanomas, 20 primary malignant melanomas, and 29 melanoma metastases. Intracytoplasmic MMP-2 immunoreactive protein was found in the ‘naevocytic nests’ of common naevi, in junctional naevus cells, and in melanoma cells. The surrounding normal skin stained negatively, except for occasional macrophages, sweat glands, and hair follicles. The number of MMP-2-positive cells increased with decreasing architectural organization and increasing atypia in the melanocytic lesions. The MMP-2 positivity in the primary and subcutaneous melanoma lesions correlated with later haematogenous metastasis. The data suggest that MMP-2 expression is an early event in melanocytic tumour progression, but is nevertheless prognostic for haematogenous metastasis in melanoma.     

Magnetocardiographic QT Interval Dispersion in Postmyocardial Infarction Patients with Sustained Ventricular Tachycardia: Validation of Automated QT Measurements

T dispersion is a measure of heterogeneity in ventricular repolarization. Increased ECG QT dispersion is associated with life-threatening ventricular arrhythmias. We studied if magnetocardiographic (MCG) measures of QT dispersion can separate postmyocardial infarction patients with and without susceptibility to sustained VT. Manual dispersion measurements were compared to a newly adapted automatic QT interval analysis method. Ten patients with a history of sustained VT (VT group) and eight patients without ventricular arrhythmias (Controls) were studied after a remote myocardial infarction. Single-channel MCGs were recorded from 42 locations over the frontal chest area and the signals were averaged. QT dispersion was defined as maximum — minimum or standard deviation of measured QT intervals. VT group showed significantly more QT and JT dispersion than Controls. QT_apex dispersions were 127 ± 26 versus 83 ± 21 ms (P = 0.004) and QT_end dispersions 130 ± 37 versus 82 ± 37 ms (P = 0.013), respectively. Automatic method gave comparable values. Their relative differences were 9% for QT_apex and 27% for QT_end dispersion on average. In conclusion, increased MCG QT interval dispersion seems to be associated with a susceptibility to VT in postmyocardial infarction patients. MCG mapping with automated QT interval analysis may provide a user independent method to detect nonhomogeneity in ventricular repolarization.     

Oral health promotion among Finnish adolescents between 1977 and 1989

In Finland a national, comprehensive preventive oriented oralhealth programme was implemented in 1972. Oral health habitsand services as well as their development were followed in theJuvenile Health Habit Study programme between 1977 and 1989.Postal questionnaires were sent to 12–18 year old Finnsevery second year from 1977. The response rates of the nationallyrepresentative samples were 79–88%. The most recent questionnairewas answered by 3220 adolescents (80%). Use of oral health services increased continuously from 1977to 1985. In 1985 there was a slight decrease in the use among16 and 18 year olds. Sex and socioeconomic differences in theuse of these services disappeared in 1985. In 1989 half of theadolescents had received instruction about oral hygiene butonly 20% about use of sugar during their last dental visit. Oral hygiene habits (toothbrushing and use of dental floss)improved slowly but continuously during the whole period Dailyuse of dental floss was still rare and one-third of the Finnishboys did not brush their teeth daily in 1989. The most common sugar-containing products used daily were hotsweet drinks (sugar-sweetened coffee, tea and hot chocolate).Use of sugar-sweetened coffee and cakes decreased but that ofsweets, soft drinks, sugar-sweetened tea and hot chocolate remainedunchanged. Use of sweetened yogurt increased slightly. The positive trend in the use of oral health services and oralhealth behaviour can be explained by the national oral healthpromotion programme. Extensive toothbrush and toothpaste advertisementsand changes in teenagers' life-style associated with urbanizationof the society may also have contributed to the improvements.     

Health behaviour in schoolchildren A WHO cross-national survey: A presentation of philosophy, methods and selected results of the first survey

"Health Behaviour in Schoolchildren. A WHO Cross-National Survey"was started by researchers from three European countries. Presently,more than 10 countries within the European region of WHO areaccepted as members of the project. The study is oriented towards behavioural and social science,and its basic philosophy is described as a lifestyle approach.In the first part of this article, differences between traditionalepidemiological research and lifestyle research are outlined.The concept "lifestyle" is clarified, and the focuses of lifestyle,health promotion and health education research are described.It is argued that aspects of lifestyle not considered to bedirectly related to mortality or morbidity may be more importantfor an understanding of lifestyle of individuals or groups thanaspects more directly related to health. Health-related habits, lifestyle and psychosocial aspects ofhealth are chosen as criterion variables of the study. The personaland environmental context of lifestyle are the main factorson the predictor side, and the findings should also be discussedin a demographic and macrosocial context. National cross-sectional surveys (n at least 3000) are carriedout regularly in an increasing number of countries. Data arecollected anonymously at school, covering three age groups (meanage 11.5, 13.5, and 15.5 years). One part of the questionnaireconsists of a core of questions and is repeated in every survey.The other part has a special focus which changes from surveyto survey. Comparability of data across countries is given highpriority. Results from the first survey (1983–84) are presentedto illustrate the relative importance of country, indicatorsof inequality, social network, and beliefs in the harmful effectsof smoking as predictors of smoking habits. The results confirmthat a wide range of predictors are important. In line with the philosophy of the project, the focus of thesecond survey (1985–86) is on physical activity (as apositive health habit) and psychosocial aspects of health. Finally the report mentions some of the more practical and administrativeproblems related to this kind of cross-national research, anddescribes some of the limitations of large-scale cross-nationalsurveys.     

Toxicokinetics of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) in Two Substrains of Male Long-Evans Rats after Intravenous Injection

Toxicokinetics of a nontoxic intravenous dose of ¹⁴C-labeledTCDD were studied in two substrains of Long-Evans (L-E) ratswith a fivefold difference in sensitivity in terms of TCDD-inducedmortality. The Turku/AB Long-Evans rat (T L-E) is the most sensitiverat strain with an oral LD50 of 17.7 µg/kg, whereas theCharles River Long-Evans rat (CR L-E) is a more resistant strain(oral LD50 95.2 µg/kg). Samples of 18 tissues were collected1, 2, 4, 8, 16, and 32 days after dosing and analyzed for radioactivity.Body weight and fecal and urinary excretion of radioactivitywere monitored daily during the 32-day study period. CR L-Erats grew significantly faster than T L-E rats, increasing theirbody weight by 60% in 32 days compared with only 16% in T L-Erats. This difference was not caused by toxicity, because theweight gain was identical in control and TCDD-treated rats ofboth substrains. Tissue concentrations of [¹⁴C]TCDD-associatedradioactivity and area under the curve (AUC) values were lowerin CR L-E than in T L-E rats. The most pronounced differenceswere found in thymus, white adipose tissue, brown adipose tissue,and adrenals. The decrease of TCDD concentration in tissueswas faster in CR L-E than in T L-E rats, whereas fecal and urinaryexcretion was faster in T L-E than in C L-E rats. Eliminationhalf-life was 20.0 days in T L-E rats and 28.9 days in CR L-Erats. Differential toxicokinetics of TCDD in the two L-E substrainsprovide a likely explanation for the greater sensitivity ofthe T L-E strain, since observed differences in tissue concentrationsand AUC values are in good agreement with the difference insusceptibility. In addition to the more efficient tissue uptakeof TCDD in T L-E rats than in CR L-E rats, the major contributingfactor to differences in toxicokinetics seems to be a differentialgrowth rate (dilution by growth), which in turn appears to providean explanation for the difference in susceptibility. More rapidexcretion of TCDD in T L-E rats than in CR L-E rats is clearlya result of higher tissue concentrations in T L-E rats. However,this faster excretion rate is not sufficient to counterbalancethe much slower dilution by growth in T L-E rats than in CRL-E rats. Thus, dilution by growth can be a more important factorin determining the toxicokinetics and toxicity of TCDD in rodentsthan is excretion.     

ACUTE ETHANOL INTOXICATION DOES NOT INFLUENCE GONADOTROPIN SECRETION IN POSTMENOPAUSAL WOMEN

Acute effects of ethanol ingestion (1.0 g per kg body weight)on the serum levels of LH, FSH and prolactin were studied in10 postmenopausal women. Ethanol was administered during thefirst 3 hr of the experiment and the hormone concentrationswere monitored for 10 hr. Each subject served as her own controlin an identical experiment without ethanol. Blood alcohol concentrationreached its maximum 1.18 ± 0.02 g/l (mean ± S.E.M.)3hr after the start of the drinking. No changes were found inthe levels of LH and FSH during the experimental period. Theincrease of 80% in the mean concentration of prolactin at 4hrafter the start of drinking was not statistically significant.On the basis of these and previous results we conclude thatalcohol has no acute effects on the secretion of gonadotropinsin women.     

Determinants of teenage smoking, with special reference to non-standard family background

The prevalence of teenage smoking in a cohort of 12 058 subjects born in northern Finland in 1966 is discussed in terms of its social and family determinants, especially in “non-standard” families (with one or more of the parents absent for at least pan of the child's upbringing). The prevalence of experimental or daily smoking was 67.4%, the rate being 65.5% in the standard, two-parent families and 75.5% in the non-standard families, the difference being statistically significant (p<0.001). The corresponding prevalence of daily smoking was 6.4%, but the rate was 5.1% in standard families and 12.1% in non-standard families (p<0.001). An elevated risk of smoking existed among adolescents who had experienced death of their father or divorce of their parents and among girls who had experienced death of their mother. Maternal smoking during pregnancy and maternal age under 20 years at the time of delivery increased the risk, while being the first-born child reduced it. Among family factors existing in 1980, paternal smoking increased the risk for both sexes, while more than three siblings, mother's unemployment or gainful employment (i.e. not a housewife) were associated with smoking by the boys as was urban living, and for the girls migration by the family to a town. The results suggest that juvenile smoking may be a kind of indicator of possible problems experienced by the parents and/or the adolescents themselves with respect to parenthood and family development.