Radiocarbon dates and Bayesian modeling support maritime diffusion model for megaliths in Europe.

There are two competing hypotheses for the origin of megaliths in Europe. The conventional view from the late 19th and early 20th centuries was of a single-source diffusion of megaliths in Europe from the Near East through the Mediterranean and along the Atlantic coast. Following early radiocarbon dating in the 1970s, an alternative hypothesis arose of regional independent developments in Europe. This model has dominated megalith research until today. We applied a Bayesian statistical approach to 2,410 currently available radiocarbon results from megalithic, partly premegalithic, and contemporaneous nonmegalithic contexts in Europe to resolve this long-standing debate. The radiocarbon results suggest that megalithic graves emerged within a brief time interval of 200 y to 300 y in the second half of the fifth millennium calibrated years BC in northwest France, the Mediterranean, and the Atlantic coast of Iberia. We found decisive support for the spread of megaliths along the sea route in three main phases. Thus, a maritime diffusion model is the most likely explanation of their expansion.

Associations between estimated acrylamide intakes, and hemoglobin AA adducts in a sample from the Malmö Diet and Cancer cohort.

OBJECTIVE: To examine the coherence of estimated intakes of acrylamide (AA) from foods, with hemoglobin (Hb) AA adduct levels, an objective marker of environmental AA exposure. DESIGN: A cross-sectional study. SETTING: The Malmö Diet and Cancer study, a large population-based prospective cohort (n=28 098) in the south of Sweden. SUBJECTS: A sample of non-smoking (n=70) and smoking (n=72) women and men selected to obtain large variation in Hb AA adducts. METHODS: Self-reported data on the usual consumption of foods were combined with published data on the AA content in Swedish foods. The Hb AA adduct levels were determined by a modified Edman degradation method. Linear regression and correlation analysis examined associations between estimated AA intakes, and Hb AA adducts. RESULTS: In randomly selected individuals (n=40), the estimated median AA intake was 28 mug per day. In linear regression models, adjusting for sex, significant associations were seen in non-smokers between Hb AA adducts and estimated AA from foods (P=0.006). In smokers both AA from foods (P=0.006) and the calculated amount of tobacco consumed (P=0.003) were significantly associated with Hb AA adducts. Positive partial correlations between dietary AA estimates and Hb AA adducts were seen in smoking men (r=0.37) and women (r=0.59), and in non-smoking men (r=0.60), but not in non-smoking women. CONCLUSIONS: This study suggests that both diet and tobacco are important sources of the environmental AA exposure, although the lack of correlations in non-smoking women cast doubt on the validity of dietary AA intake estimates used in cancer epidemiology, or suggest that unrecognized factors may influence the internal dose measure of AA exposure.

Paranasal sinus ventilation in healthy subjects and in patients with sinus disease evaluated with the 133-xenon washout technique.

Ventilation of the paranasal sinuses is of great importance in sinus pathophysiology. Therefore, methods of measuring sinus ventilation are important for the evaluation of patients with sinus disease. In the present study, a 133-xenon washout technique was used to evaluate the ventilation of the paranasal sinuses in 34 healthy subjects and in 13 subjects with sinus disease (5 patients with nasal polyposis and 8 patients with chronic sinusitis). For this purpose, a 133-xenon-air mixture was insufflated in each nostril and the washout of the radioactive gas from the paranasal sinuses was monitored with a dynamic single-photon-emission computed tomography camera. The half-time (+/-SD) was found to be 18 +/- 18 minutes for the maxillary sinus, 10 +/- 8 minutes for the frontal sinus, and 18 +/- 23 minutes for the posterior ethmoid and sphenoid sinuses in the healthy subjects. Repeated measurements in 18 of the healthy subjects indicated that the method had acceptable reproducibility according to a Bland-Altman plot. The 133-xenon washout was not influenced by insufflation pressure, nasal patency, or body position. The subjects with sinus disease exhibited half-times of 77 +/- 101 minutes for the maxillary sinus, 91 +/- 124 minutes for the frontal sinus, and 60 +/- 60 minutes for the posterior ethmoid and sphenoid sinuses. For patients with nasal polyposis, the half-time was significantly longer than that in healthy subjects, while patients with chronic sinusitis did not differ from healthy subjects in this respect.

Factors influencing 133-xenon washout in a nose-sinus model.

The 133-xenon washout technique is a non-invasive method for the evaluation of ventilation of the paranasal sinuses. The half-time of 133-xenon washout (T(1/2)) is considered to reflect sinus ostial function and sinus ventilation. However, it is not known how morphological and physiological factors affect the washout from the paranasal sinuses. The aim of the present study was to evaluate how sinus volume, ostial diameter and nasal ventilation influence 133-xenon washout in a nose-sinus model. This is important for the interpretation of measurements of 133-xenon washout from paranasal sinuses in healthy subjects and in subjects with sinus disease. The 133-xenon washout was measured with a scintillation camera. The statistical analysis of the results showed that the logarithm (to the base 10) of the half-time of 133-xenon washout is linearly related to the ostial diameter, the sinus volume and the nasal ventilation in the model. In a multiple linear regression model, the most important factor contributing to 133-xenon washout was found to be the ostial diameter, which explained 76% of the variation in log T(1/2). In the same statistical model the sinus volume explained 7.5% and the ventilation 5.3% of the variation in log T(1/2). Calculations of the functional ostial diameter in healthy subjects were made, based on the results of the model study. The mean functional ostial diameter was found to be 3.5 mm (range 0.5-7.5 mm). The results obtained with the present model experiments may be of importance for the correct interpretation of the results of measurements of 133-xenon washout in healthy subjects and patients.

The multiplicative model for cancer risk assessment: applicability to acrylamide.

According to a multiplicative model for prediction of cancer risk for genotoxic agents the incremental cancer risk is, for low-intermediate exposures, proportional to target doses of the genotoxic substance and to the background risk in control groups. This model has been applied to evaluate cancer tests of acrylamide in rodents. Because of its reactivity toward DNA, glycidamide is assumed to be the causative genotoxic metabolite of acrylamide. Evaluation of experimental data according to the multiplicative model shows that mice, compared with rats, are of the order of 10 times more sensitive per administered dose of acrylamide. The US EPA procedure would, however, generally predict rats to be about twice as sensitive as mice to carcinogenic chemicals, because their estimates are based on scaling of the dose per square meter body surface area, as a surrogate for metabolic differences between the species. The comparison of rats and mice with respect to observed cancer incidence is at a key position in the evaluation of the usefulness of risk models for extrapolation between species. In the present study mice and rats were compared, with respect to in vivo doses of acrylamide and the metabolite glycidamide, after exposure to acrylamide. The relative in vivo doses were inferred from levels of hemoglobin adducts. The adduct levels from glycidamide were, per administered dose of acrylamide, approximately 3-10 times higher in mice than in rats. In combination with the above mentioned higher sensitivity of mice than rats in cancer tests of acrylamide this is compatible with the concept that glycidamide is the key genotoxic factor in acrylamide exposure. Furthermore, it is shown that the multiplicative, i.e. relative, risk model and measurements of the dose of the genotoxic factor give good prediction of the observed risk from acrylamide in cancer tests with rats and mice.

Nasal mucosal congestion during the menstrual cycle.

A relationship between the reactivity of the nasal mucosa and changes in female sex hormones have been debated for a long time, although no evidence has been presented to prove or disprove this relationship. Nasal patency was therefore measured by nasal expiratory peak-flow in 26 women for two months in order to study changes in nasal mucosal congestion during the menstrual cycle. In another eight women, nasal congestion was measured by acoustic rhinometry, and symptoms of nasal stuffiness were registered during periods when there were various levels of plasma oestradiol and progesterone. Finally, nasal mucosal biopsies were taken for preparation of receptors for oestradiol and progesterone. This study could not verify the effects of female sex hormones on the nasal mucosa. This could be explained by the fact that no receptors for oestradiol and progesterone were found.

Ventilation of the paranasal sinuses studied with dynamic emission computer tomography.

This investigation's aim was to study a noninvasive method for determining the ventilation of the nasal sinuses. For this purpose, different insufflation techniques using xenon 133 were tried, along with different scintillation camera techniques. Xenon 133 gas was used for insufflation in the nose and sinuses, and the half-time of the washout curves was determined with the aid of digital scintillation cameras, one of which was capable of dynamic tomography. The tomographic procedure was superior because it made it possible to study the washout from the ethmoidal/sphenoidal sinuses as well. The washout was followed for up to 150 minutes. Great variations in washout were found between different sinuses and also in the same sinus over time. The single photon emission computed tomography (SPECT) technique, which is easy to perform and gives a limited absorbed dose to the patient, seems promising for the future evaluation of sinus ventilation and ostial function.

Treatment of snoring--with and without carbon dioxide laser.

Thirty patients with bedpartners complaining of their heavy snoring which had resulted in separate bedrooms were treated surgically. Three different methods were used, each group consisted of 10 patients. In group A conventional scalpel excision was used for uvulopalatopharyngoplasty including tonsillectomy. In groups B and C, patients with small tonsils were selected and therefore the tonsils were saved. Group B was operated with carbon dioxide laser under a microscope and using micromanipulator. The same kind of excision was used as in group A but the tonsils were saved. Group C was operated as group B but using conventional scalpel excision technique. With a starting-point of snoring score 3 preoperatively in all groups, the mean postoperative snoring score in Group A was 1.0, in Group B 0.2 and in Group C 1.1. Patients with postoperative snoring scores of 0 and 1 were regarded as successful responders to surgery. No serious side effects were noted due to treatment.

Nasal mucosal blood flow at rest and during exercise.

Nasal airway resistance increases at rest in the supine position and decreases during exercise due to changes of the thickness of the nasal mucosa regulated by the capacitance vessels. The resistance vessels regulating blood flow have not not been evaluated in these conditions before. In 15 healthy subjects the nasal mucosal blood flow was measured in rest and exercise with the 133Xe washout method. No change in blood flow was registered during exercise, which demonstrates that the blood flow and the blood content of the human nasal mucosa are not affected in the same way by exercise.

Tympanometry before and during nitrous oxide anesthesia with middle ear effusion.

During nitrous oxide anesthesia the nitrous oxide passes from blood to the normal middle ear space. Middle ear pressures before and during anesthesia in ears of pediatric patients with secretory otitis media have been measured with tympanometry. The subjects were divided into groups depending on the primary middle ear pressure and the pressure change during anesthesia. The reason for the different tympanometric findings in patients with secretory otitis media might be differences in the states of the mucous membrane of the middle ear. The usefulness of measuring middle ear pressures during nitrous oxide anesthesia is discussed.