Bilateral Force Deficit in Proximal Effectors Versus Distal Effectors in Lower Extremities.

Purpose: Bilateral force deficit occurs when the maximal generated force during simultaneous bilateral muscle contractions is lower than the sum of forces generated unilaterally. Neural inhibition is stated as the main source for bilateral force deficit. Based on differences in bilateral neural organization, there might be a pronounced neural inhibition for proximal compared to distal effectors. The aim of the present experiment was to evaluate potential differences in bilateral force deficit in proximal compared to distal effectors in lower extremities. Methods: Fifteen young adults performed single-joint maximal voluntary contractions in isometric dorsiflexion of ankle (distal) and knee (proximal) extension unilaterally and bilaterally. Results: Results showed a significant absolute bilateral force deficit for both proximal (123.46 ± 59.51 N) and distal effectors (33.00 ± 35.60 N). Interestingly, the relative bilateral force deficit for knee extension was significantly larger compared to dorsiflexion of ankle, 19.98 ± 10.04% and 10.27 ± 9.57%, respectively. Our results indicate a significantly higher bilateral force deficit for proximal effectors compared to distal effectors. Conclusion: Plausible explanations are related to neuroanatomical and neurophysiological differences between proximal effectors and distal effectors where proximal muscles have a higher potential for bilateral communication compared to distal muscles. In addition, higher forces produced with proximal effectors could cause a higher perceived exertion and cause a more pronounced bilateral force deficit to proximal effectors.

Placental inflammation in pre-eclampsia by Nod-like receptor protein (NLRP)3 inflammasome activation in trophoblasts.

Pre-eclampsia is associated with increased levels of cholesterol and uric acid and an inflamed placenta expressing danger-sensing pattern recognition receptors (PRRs). Crystalline cholesterol and uric acid activate the PRR Nod-like receptor protein (NLRP)3 inflammasome to release interleukin (IL)-1ß and result in vigorous inflammation. We aimed to characterize crystal-induced NLRP3 activation in placental inflammation and examine its role in pre-eclampsia. We confirmed that serum total cholesterol and uric acid were elevated in pre-eclamptic compared to healthy pregnancies and correlated positively to high sensitivity C-reactive protein (hsCRP) and the pre-eclampsia marker soluble fms-like tyrosine kinase-1 (sFlt-1). The NLRP3 inflammasome pathway components (NLRP3, caspase-1, IL-1ß) and priming factors [complement component 5a (C5a) and terminal complement complex (TCC)] were co-expressed by the syncytiotrophoblast layer which covers the placental surface and interacts with maternal blood. The expression of IL-1ß and TCC was increased significantly and C5a-positive regions in the syncytiotrophoblast layer appeared more frequent in pre-eclamptic compared to normal pregnancies. In-vitro activation of placental explants and trophoblasts confirmed NLRP3 inflammasome pathway functionality by complement-primed crystal-induced release of IL-1ß. This study confirms crystal-induced NLRP3 inflammasome activation located at the syncytiotrophoblast layer as a mechanism of placental inflammation and suggests contribution of enhanced NLRP3 activation to the harmful placental inflammation in pre-eclampsia.

Empty iron stores in children and young adults--the diagnostic accuracy of MCV, MCH, and MCHC.

INTRODUCTION: Erythrocyte mean cell volume (MCV) is used clinically to classify anemia, and normal values may be used to exclude iron deficiency. We have studied the diagnostic accuracy of MCV and the related measures mean cell hemoglobin (MCH) and mean cell hemoglobin concentration (MCHC) in diagnosing empty iron stores in children and young adults. METHODS: Diagnostic accuracy of MCV, MCH, and MCHC was studied by ROC curve analysis in 6443 ambulant patients aged 0.5-25 years, of which 476 were anemic. In all patients, blood hemoglobin, MCV, MCH, and serum ferritin were measured in specimens sampled at the same time. MCHC was calculated as MCH divided by MCV. The gold standard of empty iron stores was s-ferritin <10, 15, or 20 µg/L. The cutoff limit of MCV giving 90% sensitivity in diagnosing serum ferritin <15 µg/L was constructed using quantile regression. RESULTS: Generally, MCH was slightly more accurate than MCV and MCHC. In the whole study population, the area under the ROC curve was 0.68-0.93 for MCV, 0.73-0.96 for MCH, and 0.68-0.87 for MCHC; and 0.70-0.86, 0.71-0.89, and 0.68-0.88, respectively, in the anemic subpopulation. At the cutoff limits of MCV giving a sensitivity of 90% at all ages in anemic patients, the specificity was about 50%. CONCLUSION: Mean cell hemoglobin, MCH, and MCHC are only moderately accurate in diagnosing empty iron stores in children and young adults, and normal values of these tests do not exclude empty iron stores in anemic patients.

Comparison of bilateral force deficit in proximal and distal joints in upper extremities.

Bilateral force deficit refers to the phenomenon that maximal generated force during simultaneous bilateral muscle contractions is lower than the sum of forces generated unilaterally. Based on the notion that neural inhibition is the main source for bilateral force deficit and existing differences in neural inhibiting interhemispheric organization of proximal and distal muscles, we expected differences in bilateral deficit in proximal and distal joints. The aim of the current behavioral experiment was to compare bilateral force deficit in proximal compared to distal upper extremity joints. Ten young adults performed single-joint maximal voluntary contractions in isometric flexions of the shoulder and index finger unilaterally and bilaterally. The results showed a significant absolute bilateral force deficit for both proximal (140.01 ± 86.99 N) and distal muscles (4.64 ± 4.86 N). More importantly, relative bilateral force deficit for shoulder flexion was significantly larger than for index finger flexion, -20.51 ± 7.8% and -5.07 ± 3.84% respectively. The hypothesis of a more pronounced bilateral force deficit for proximal compared to distal muscles was confirmed in our results. Thus, our findings, in combination with the neuroanatomical differences for proximal and distal muscles, make it worthwhile to further explore the hypothesis that the commissural fibers provide differences in interhemispheric inhibitory interactions during bimanual actions for proximal and distal muscles.

Comparisons of polybrominated diphenyl ether and hexabromocyclododecane concentrations in dust collected with two sampling methods and matched breast milk samples.

UNLABELLED: Household dust from 19 Swedish homes was collected using two different sampling methods: from the occupant's own home vacuum cleaner after insertion of a new bag and using a researcher-collected method where settled house dust was collected from surfaces above floor level. The samples were analyzed for 16 polybrominated diphenyl ether (PBDE) congeners and total hexabromocyclododecane (HBCD). Significant correlations (r = 0.60-0.65, Spearman r = 0.47-0.54, P < 0.05) were found between matched dust samples collected with the two sampling methods for ∑OctaBDE and ∑DecaBDE but not for ∑PentaBDE or HBCD. Statistically significantly higher concentrations of all PBDE congeners were found in the researcher-collected dust than in the home vacuum cleaner bag dust (VCBD). For HBCD, however, the concentrations were significantly higher in the home VCBD samples. Analysis of the bags themselves indicated no or very low levels of PBDEs and HBCD. This indicates that there may be specific HBCD sources to the floor and/or that it may be present in the vacuum cleaners themselves. The BDE-47 concentrations in matched pairs of VCBD and breast milk samples were significantly correlated (r = 0.514, P = 0.029), indicating that one possible exposure route for this congener may be via dust ingestion. PRACTICAL IMPLICATIONS: The statistically significant correlations found for several individual polybrominated diphenyl ether (PBDE) congeners, ∑OctaBDE and ∑DecaBDE between the two dust sampling methods in this study indicate that the same indoor sources contaminate both types of dust or that common processes govern the distribution of these compounds in the indoor environment. Therefore, either method is adequate for screening ∑OctaBDE and ∑DecaBDE in dust. The high variability seen between dust samples confirms results seen in other studies. For hexabromocyclododecane (HBCD), divergent results in the two dust types indicate differences in contamination sources to the floor than to above-floor surfaces. Thus, it is still unclear which dust sampling method is most relevant for HBCD as well as for ∑PentaBDE in dust and, further, which is most relevant for determining human exposure to PBDEs and HBCD.

Treatment outcome in patients with TMD--a survey of 123 patients referred to specialist care.

Temporomandibular disorders (TMD) are a group of functional disorders of the masticatory system. Signs and symptoms of TMD are very common in different age groups in both genders. Treatment need varies greatly, ranging from 5 to 27% of the population. The treatment of TMD patients is generally initiated using reversible conservative methods and if necessary, irreversible and surgical methods are used. Altogether 123 patients (93 females, 30 males, mean age 39 years, range 12 to 72 years) were referred to the Oral and Maxillofacial Department of Oulu University Hospital between the years 2005 and 2008. The treatment outcome was evaluated using the anamnestic and clinical dysfunction indices of Helkimo, before and after treatment. The results of the study showed that the outcome of the conservative treatment methods of TMD and of surgical treatment, if needed, was beneficial, with a subjectively and clinically statistically significant decrease in signs and symptoms.

POP levels in breast milk and maternal serum and thyroid hormone levels in mother-child pairs from Uppsala, Sweden.

In experimental studies, it has frequently been observed that the homeostasis of thyroid hormones (THs) is affected by exposure to persistent organic pollutants (POPs), such as dioxins and PCBs. In man, similar effects have been indicated in several epidemiological studies. In order to investigate the possible effect on THs at low background exposures found among the Swedish population the following study was performed. Primiparous women (n=395) in the Uppsala region were recruited between 1996 and 1999. Of these, 325 mothers agreed to donate a serum sample in late pregnancy and breast milk was obtained from 211 women 3 weeks after delivery. Babies were sampled for blood at 3 weeks (n=150) and 3 months (n=115) after birth. In connection to the sampling, questions on personal characteristics were asked. Levels of low (tri- to penta-) chlorinated PCB, di-ortho PCB, p,p'-DDE, (mono-ortho) PCB TEQ and PCDD/DF TEQ were monitored in breast milk and in mother's blood (not PCDD/DF). The results showed that the measured TH levels (thyroid-stimulating hormone - TSH, total tri-iodothyronine - TT3, free thyroxine - FT4) in mothers and children were within the reference range. Some significant associations were seen between POP exposures and TH levels in mother or child after simple regression analysis. Following adjustment for important confounding factors, the significant associations mostly disappeared. However, significantly decreasing TT3 levels with increasing prenatal low-chlorinated PCB exposure were still seen in 3 week old children, and on TT3 in mothers exposed to PCDD/DF. In conclusion, the study clearly shows the importance of adjustment for important confounding factors in the analysis of possible associations between POP exposure and hormonal effects. The remaining associations are weak in both children and mothers and the clinical consequences of these alterations are uncertain. When comparing studies that investigate associations between TH levels and POP levels during the perinatal stage, no obvious between-study concordance was seen regarding the critical dose for hormonal effects to occur.

Association of stress level with facial pain: the role of coping.

It has been noted that stress factors, including coping with stress, are involved in pain problems. The aim of the present study was, firstly, to investigate the association of stress level with facial pain, and secondly, to assess the influence of coping strategies on this association. The study was part of the Northern Finland Birth Cohort 1966 project. The original material consisted of all people born in 1966 in Northern Finland. Of these, 5,696 participated in a follow-up study at the age of 31. As part of the study, data on facial pain, stress level of the subjects (measured with three items from the Work Ability Index), coping strategies in stressful situations (measured using the Ways of Coping Checklist) and sociodemographic background data were collected using questionnaires in 1997-98. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using generalized linear models. After adjustment for gender, education, and work history, facial pain was associated with a high stress level (OR 2.3, 95% CI 1.7-3.0). When coping strategies were added to the model, the strength of the association did not change essentially. The results emphasize the role of psychological stress in the background of facial pain. The association is independent of the coping strategy of the individual.

Dietary intake estimations of organohalogen contaminants (dioxins, PCB, PBDE and chlorinated pesticides, e.g. DDT) based on Swedish market basket data.

By use of a Swedish Market basket study from 1999, in which foods were sampled from four regions, the dietary intake of persistent organic pollutants (POPs) was assessed. Based on earlier data, six food groups (fish, meat, dairy products, egg, fats/oils, and pastries; comprising 52 food items) were selected for POP analyses. Homogenates from these six groups were subjected to POP analyses and levels presented on dioxins (PCDD/PCDFs), dioxin-like PCBs, PCB-153, summation operatorPCBs, BDE-47, summation operatorPBDEs, DDE, summation operatorDDTs, HCB, summation operatorHCHs, and summation operatorchlordanes, after adjusting non-quantified levels to 1/2 LOQ. For all compounds, the fish homogenate contained the comparatively highest levels, on a fresh weight basis. Intake calculations based on the six food groups showed that summation operatorPCBs and summation operatorDDTs gave per capita intakes of 615 and 523 ng/day, respectively, that the estimated summation operatorPBDE intake was 51 ng/day and that of dioxins and dioxin-like PCBs was 96 pg WHO-TEQ/day. The estimated mean intakes were below (total-TEQ: 1.3 pg/kgbw/day) or well below (summation operatorDDTs: 8.9 ng/kgbw/day) internationally agreed intake limits (total-TEQ: 2 pg/kgbw/day; summation operatorDDTs: 10,000 ng/kgbw/day). A number of uncertainty factors, including analytical limitations due to low POP levels in food, give reason for caution in the use of the presented intake data. However, the intake estimations of dioxins, summation operatorPCBs and summation operatorPBDEs are well in accordance to calculations of POP intakes in Sweden made by alternate methods.

Stress distribution in bone: single-unit implant prostheses veneered with porcelain or a new composite material.

The purpose of this study was to simulate dynamic and static occlusal loading on one unit fixed, implant-supported prostheses veneered with porcelain and with GRADIA in a 3-dimensional finite element model of the human mandible to analyze and compare the resultant stresses in the superstructures and in the supporting bone. Calculation and visualization of stress, deformation, and displacement of complex structures under simulated forces were evaluated by finite element analysis (FEA) using ANSYS. The device employed was from the OSTEOFIX Dental Implant System (Oulu, Finland), and the veneering materials used were standard dental porcelain and GC GRADIA (Tokyo, Japan), a new composite material. Two different loading conditions were considered: static and transitional or impact, each delivered in three different directions: horizontal (Fh) at 0 degrees , vertical (Fv) at 90 degrees , and oblique (Fo) at 120 degrees . The proportion of the force: magnitude was fh:fv:fo = 1:3.5:7. A vertical load of 500 N, a horizontal load of 143 N, and an oblique load of 1000 N were applied. The results showed that the highest stresses in the bone-implant interface occurred in the region of cortical bone adjacent to the first thread of implants in all models and varied within 6.5%. Maximum stresses and displacements were higher (7%) in those models with statically loaded implants as compared with those that had been dynamically loading. The direction of loading played a major role in determining stress levels and they varied at up to 85%. It was shown that with dynamic loads, the peak of 1.568 mm was registered in the model with the GRADIA veneering material. This displacement was 6.5% higher than that found with the Vita VMK 68 veneers. These results suggest that the implant superstructure-fixed single crown veneering materials-porcelain and GRADIA played minor influences to the displacements and stresses in the implant supported bone with a 1% variance. One of the reasons for this element resulting in so minor a contribution to stress relief was the relatively small volume of the veneers as compared with the far greater volume and stiffness of the superstructures and implants. One of the advantages of GC GRADIA is that it reduces impact force under dynamic load up to a 6.5%.

Generalized pain and pain sensitivity in community subjects with facial pain: a case-control study.

AIMS: To investigate the existence of pain outside the facial area as well as pain sensitivity in a population-based sample of 34-year-old subjects with facial pain. METHODS: Fifty-two facial pain cases (10 men, 42 women) and 52 pain-free controls (10 men, 42 women) included in the Northern Finland Birth Cohort of 1966 underwent a clinical musculoskeletal examination. Pain outside the facial area during the week prior to the examination was defined by means of a pain drawing. Eighteen fibromyalgia points were palpated in response to digital palpation with an algometer. Pressure pain thresholds were measured from the dorsal side of the wrist and from the highest points of the temporalis muscles. RESULTS: Compared to controls, pain cases reported significantly more pain in areas outside the face, with the exception of the shoulder and lower back. The number of painful fibromyalgia points was significantly higher in cases than in controls. Mean pressure pain thresholds were slightly lower in cases than in controls; the difference was significant in the left wrist. CONCLUSION: Subjects with facial pain reported more pain and had more mascular tenderness outside the facial area compared to controls. Pain symptoms outside the facial area should be assessed in patients seeking treatment for facial pain, and they should be taken into account when treatment is planned.

An instrument for the optimal guiding of osseointegrated dental implants.

The purpose of this study was to design an instrument for the optimal guiding of osseointegrated implants intraoperatively to achieve parallelism or desired angulations. Seven patients (4 males and 3 females) were enrolled in the investigation. They ranged in age from 44 to 61 years. Using an instrument designed by the senior author that permitted optimal guiding of the osteotomy instruments (33 Osteofix Oy, Oulu, Finland) we placed in these patients, root form, single stage implants. The difference in angulations between the first and the remaining implants was measured using the abutment replicas on the working models. It was found that the mean deviation angle between the first and the adjacent implant replicas was 2.2 degrees (SD = 0.4 degrees). The largest deviation angles were 2.3 degrees (SD = 0.5 degrees) and 3.1 degrees (SD = 0.8 degrees). The study indicated that the instrument had been designed in a functional manner and that all implants in such relationships can be inserted into their desired positions, either parallel to one another or with the desired angle for the planned prostheses.

Accuracy of clinical and radiological classification of the jawbone anatomy for implantation--a survey of 374 patients.

The aim of this study was to investigate the anatomical features of edentulous jaw dental segments (eJDS) in order to offer the most reliable clinical and radiological classification of such segments in planning for implant treatment. A total of 374 patients, 156 men and 218 women, participated in the investigation. The mean age of the patients was 46 years (SD 12.7), ranging between 17 and 73 years. The eJDS were estimated by means of orthopantomogram, computerized tomography, and intraorally with special ridge-mapping callipers for measurement of alveolar process width. A total of 792 screw-shaped and 1-stage Osteofix Dental Implant System (Oulu, Finland) implants were inserted. Dental segments were divided according to the results of the commonly accepted eJDS assessments into 3 clinical-anatomical types. Type I indicated insignificant or no atrophy of eJDS (232 patients with 476 implant sites; 60.1% of the total number). Type II indicated mild to moderate vertical or horizontal atrophy of eJDS (100 patients with 222 sites; 28% of the total number). Type III indicated significant vertical or horizontal atrophy of eJDS (42 patients with 94 sites; 11.9% of the total number). The accuracy of the clinical and radiological classification was adjudged to have been 95.8%. By the process of establishing clinical and radiological classification of the jawbone segments, more reliability was anticipated regarding the insertion of implants both in maxillae and mandibles.

Methyl mercury and inorganic mercury in Swedish pregnant women and in cord blood: influence of fish consumption.

We studied exposure to methyl mercury (MeHg) in Swedish pregnant women (total mercury [T-Hg] in hair) and their fetuses (MeHg in cord blood) in relation to fish intake. The women were recruited at antenatal care clinics in late pregnancy to participate in an exposure study of environmental pollutants. Fish consumption was evaluated using food frequency questionnaires including detailed questions on fish consumption. In addition, we determined inorganic mercury (I-Hg) and selenium (Se) in cord blood. On average, the women consumed fish (all types) 6.7 times/month (range 0-25 times/month) during the year they became pregnant. They reported less consumption of freshwater fish--species that might contain high concentrations of MeHg--during than before pregnancy. T-Hg in maternal hair (median 0.35 mg/kg; range 0.07-1.5 mg/kg) was significantly associated (R2 = 0.53; p < 0.001) with MeHg in cord blood (median 1.3 microg/L; range 0.10-5.7 microg/L). Both hair T-Hg and cord blood MeHg increased with increasing consumption of seafood (r = 0.41; p < 0.001 and r = 0.46; p < 0.001, respectively). Segmental hair analysis revealed that T-Hg closer to the scalp was lower and more closely correlated with MeHg in cord blood than T-Hg levels in segments corresponding to earlier in pregnancy. We found a weak association between Se (median 86 microg/L; range 43-233 microg/L) and MeHg in cord blood (r = 0.26; p = 0.003), but no association with fish consumption. I-Hg in cord blood (median 0.15 microg/L; range 0.03-0.53 microg/L) increased significantly with increasing number of maternal dental amalgam fillings.

Temporomandibular disorders, occlusion, and neck pain in subjects with facial pain: a case-control study.

The etiology of facial pain is multifactorial. Based on the results of a questionnaire included in the study of the 1966 Northern Finland Birth Cohort, performed in 1997-98, we found an association of facial pain with subjective symptoms of temporomandibular disorders (TMD), neck pain and with occlusal factors reported by 5,696 subjects. The aim of the present study was to examine these associations clinically. In the year 2000, a new inquiry was sent to the following subjects living in Oulu: 1. all subjects who had reported facial pain in the former questionnaire (n=162) (case group); and 2. to a randomly selected group of nonpain controls (n=200), group matched for gender. Those who reported willingness to participate were invited to a clinical examination. Finally, the total number of subjects was 104, including 52 (10 men, 42 women) cases and 52 (10 men, 42 women) controls. Anamnestic data were collected, and clinical stomatognathic and musculoskeletal examinations were performed, both the clinicians and the subjects being unaware of the case-control status. Anamnestically, stress was the most often reported provoking factor for facial pain. Facial pain associated significantly with reported TMD symptoms and allergies. Based on clinical findings, most of the cases were classified in the myogenous subgroup of TMD. The risk for facial pain was six-fold in subjects with clinically assessed TMD, defined as moderate (DiII) or severe (DiIII) by Helkimo's clinical dysfunction index, almost six-fold in subjects with protrusion interferences and approximately three-fold in subjects with clinically assessed tenderness of distinct fibromyalgia (FM) points in the neck. According to the adjusted logistic regression analyses, TMD had the strongest influence on facial pain, followed by protrusion interferences, anamnestically reported allergies and "other headaches". The present study shows that as well as being connected with TMD, facial pain is associated with pain and muscle tenderness in the neck area.

MR abnormalities of the lateral pterygoid muscle in patients with nonreducing disk displacement of the TMJ.

The aim of this study was to investigate the pathological changes of the lateral pterygoid muscle (LPM) using magnetic resonance imaging (MRI) in patients with anterior disk displacement with nonreduction (ADDnr) of the temporomandibular joint (TMJ) and to compare the abnormal findings of the LPM with the clinical symptoms and other pathological MRI alterations of the TMJ. Bilateral or unilateral ADDnr was demonstrated in 142 patents by MRI (176 TMJs; 106 females; 36 males; range 19 to 72 years; mean 43.9 years). In 123 TMJs, the LPMs were clearly observed in MRIs and analyzed in this study. Pathological changes of the LPM were found in 92 TMJs (74.8%) in MRI. Hypertrophy, atrophy and/or contracture were detected in the superior belly of the LPM (SBLPM) (35.8%, 44/123) or in the inferior belly of the LPM (IBLPM) (9.8%, 12/123) or in both bellies (29.3%, 36/123). The pathological changes of the LPM in MRI presented a significant association with the main clinical symptoms of TMJs with ADDnr, i.e. pain on jaw movement (P<0.01), pain in the LPM (P<0.01), pain in TMJ (P<0.05) and restricted jaw opening (P<0.05). The proportion of the abnormalities in LPM was significantly lower in TMJs with condylar limitation (63.6%) than in TMJs with condylar hypermobility (83.3%) and normal motion (88.9%)(P=0.008). Osteoarthritis was found to be correlated with condylar limitation (P<0.01). The results of this study indicate that the pathological changes of the LPM in TMJs with ADDnr could be detected by MRI and have a significant association with the main clinical symptoms of the patients. When condylar limitation happened, on the contrary, the pathological changes of the LPM in MRI were reduced. The alteration of the clinical symptoms in the patents with ADDnr might be associated with the pathological situations and symptoms of the LPM.

Polychlorinated biphenyl congeners as markers of toxic equivalents of polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in breast milk.

In breast milk, concentrations of polychlorinated biphenyls (PCBs) are higher than those of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), making PCB analyses less time-consuming and expensive. We searched for PCB "markers" of PCDD/DF concentrations, by studying associations between concentrations of PCB and PCDD/DFs (expressed as toxic equivalents, TEQs) in breast milk from 27 women (primiparas, 22-35 years). These women donated breast milk in 1996-1999 together with 183 other primiparas from Uppsala County, Sweden. Regression analyses showed that both dioxin-like and non-dioxin-like penta- to hepta-chlorinated PCBs could be used as markers of TEQ concentrations in this group of women, in some cases after age adjustment of the regressions. The strong positive association between concentrations of dioxin-like PCB/DD/DFs and non-dioxin-like PCBs will in future epidemiological studies make it difficult to separate Ah receptor-dependent effects from non-Ah receptor-dependent effects. With the use of regression equations and concentrations in breast milk samples collected in 1994, TEQ concentrations were estimated in the 1994 samples. Comparisons between estimated and measured concentrations indicated that associations between concentrations of marker substances and TEQs should be determined separately within each study population, in order to obtain reliable TEQ exposure assessments from PCB markers.

Potential nitrite scavengers as inhibitors of the formation of N-nitrosamines in solution and tobacco matrix systems.

The ability of 20 compounds, all but one tobacco constituents, to inhibit the formation of tobacco-specific N-nitrosamines (TSNA) was investigated in buffer and detergent solution and in tobacco midrib and lamina systems. In solution at pH 5.5, ascorbic acid and the phenolic acids caffeic and ferulic acid were the most potent inhibitors of the reaction between nornicotine and nitrite, with nearly complete inhibition at molar ratios test compound/nitrite > 1:1. Also, cysteine > dihydrocaffeic acid > protocatechuic acid approximately catechin acted as strong inhibitors with >90% inhibition at a ratio of 3:1. Lower inhibitions were observed with chlorogenic acid > p-coumaric acid > sclareol > serine. Rutin showed an inhibition of 34% at a ratio of 0.1:1. Sclareol, alanine, proline, and serine did not significantly affect the N-nitrosonornicotine (NNN) formation. alpha-Tocopherol and glutathione enhanced NNN formation at pH 5.5 but were inhibitors at pH 3. Cinnamic acid, vanillic acid, eugenol, and esculin enhanced NNN formation. Increased NNN formation was also observed for dihydrocaffeic acid, chlorogenic acid, protocatechuic acid, and catechin at a less-than-equimolar ratio of test compound to nitrite. The tobacco matrix experiments were performed with air-cured, ground tobacco midrib and lamina. Caffeic acid, ferulic acid, dihydrocaffeic acid and catechin were potent inhibitors of the formation of TSNA in the midrib as well as in the lamina. Also protocatechuic acid, glutathione, ascorbic acid, p-coumaric acid, chlorogenic acid and cysteine were inhibitors, while alpha-tocopherol and rutin inhibited the reaction in the midrib but not in the lamina. Cinnamic acid, vanillic acid, eugenol, alanine, proline and serine showed small effects only. The molar ratio of secondary alkaloid(s)/nitrite in the test systems were 0.1:1 (solution), approximately 0.25:1 (midrib), and approximately 1:1 (lamina) and is most likely the major contributor to the observed order of inhibition potency (solution > midrib > lamina) of the test compounds. The vicinal phenolic hydroxyl groups of polyphenols and the simultaneous presence of a phenol group and an olefinic bond in hydroxycinnamic acids were the most characteristic structural elements of the potent inhibitors.

Automated counting of white and red blood cells in the cerebrospinal fluid.

The objective of this study was to examine to what extent the automated method of the Bayer H*2 instrument could replace the visual counting of white and red blood cells in cerebrospinal fluid. The number of white blood cells as well as the percentage of mononuclear and polymorphonuclear cells were counted in the 'Baso channel' (Research screen 3) whereas the number of red cells were registered as the 'R-count' (Research screen 1). All automated cell counts were compared to visual estimates. The automated count yielded reliable results down to 5 x 106 white blood cells/l and 5 x 108 red blood cells/l. In some samples 'noise' was present in the Baso channel. A correct white blood cell count could then be obtained by counting the cells directly as dots on the screen. It was possible to differentiate between polymorphnuclear cells and mononuclear cells at all WBC concentrations. The automated counting of cerebrospinal fluid can be performed without changing thresholds or sample volumes of the instrument. Thus, in the routine practice it will be possible to alternate between automated counting of whole blood samples and cerebrospinal fluid samples.

Toxaphene levels in salmon (Salmo salar) from the Baltic Sea.

Three toxaphene congeners have been determined in salmon from the Swedish coastal environment using both supercritical fluid (SFE) and the traditional liquid/liquid extractions. The levels obtained using a modifier-free SFE technique, followed by group separation on a silica gel column, were by far much lower than concentrations obtained by SFE with a modifier or liquid/liquid extraction. The mean concentrations on fresh weight basis using a liquid/liquid extraction technique were 5.87, 8.70 and 1.59 microg/kg for CHBs 26, 50 and 62, respectively. There was a plausible relationship between the various fishing sites and the toxaphene levels.