Analysis of exhaled leukotrienes in nonasthmatic adult patients with seasonal allergic rhinitis

BACKGROUND

Leukotrienes (LTs) are increased in exhaled breath condensate (EBC) in patients with asthma. So far no data have been reported about LT levels in nonasthmatic patients with seasonal allergic rhinitis (SAR). The aim of the study was to find out whether the LT levels in EBC were increased in the nonasthmatic adult patients with SAR both during and after the pollen season in comparison with healthy controls and to assess the changes of the LT levels after the pollen season.

METHODS

Twenty-nine nonasthmatic adult patients with SAR underwent measurement of exhaled LTs in the EBC during and after the pollen season. Leukotrienes B(4), C(4), D(4) and E(4) were analysed by a specific and sensitive gas chromatography/mass spectrometry (GC/MS) assay and compared with 50 healthy nonsmoking controls. Spirometry, skin prick tests and nonspecific IgE were evaluated.

RESULTS

Leukotrienes concentrations (B(4), E(4) but not D(4)) were significantly increased in and after the pollen season in patients with SAR in comparison with healthy controls. In most of the samples, LT C(4) was undetectable. The values of all exhaled LTs were significantly decreased after the pollen season compared with the seasonal baseline: LTB(4) (P = 0.023), LTD(4) (P = 0.020), LTE(4) (P = 0.047).

CONCLUSIONS

Levels of exhaled LTB(4) and LTE(4) were higher in SAR patients than in healthy controls and decreased after the pollen season as compared with levels in season. The SAR patients with the highest in season LT levels had also the post-season levels elevated and this may be an early marker of inflammatory process in the lower airways despite the absence of clinical symptoms of asthma.

[Deferral of coronary intervention based on measurement of myocardial fractional flow reserve]

BACKGROUND

Myocardial fractional flow reserve (FFR) is a useful method in assessment of functional significance of coronary stenosis. Deferral of intervention of angiographically intermediate lesion based on FFR measurement is safe in selected patient population as previously described. The aim of the study was to assess mid-term results after deferring coronary intervention of intermediate lesion in a non-selected patient population with no respect to the extent of coronary artery disease and to the results of stress tests if performed.

METHODS

A coronary intervention of angiographically intermediate lesion (40 - 70% according to QCA) was deferred in a group of 50 consecutive patients (33 men, mean age 60.8 +/- 10.2 y.) on the basis of FFR > or = 0.75 (mean FFR 0.89 +/- 0.06). FFR was measured in 62 lesions (mean stenosis diameter 55 +/- 7%, left anterior descending 34 lesions, circumflex artery 13 lesions, right coronary artery 15 lesions). One-vessel disease was presented in 14 pts (28%), 36 pts (72%) presented with multivessel disease (two-vessel disease in 27 pts - 54% and three-vessel disease in 9 pts - 18%). Stress test was positive in 15 pts, in 1 pts. negative, and in 3 pts. non-diagnostic. All-cause mortality, cardiac mortality, non-fatal myocardial infarction (MI) and ischemia driven target vessel revascularization (TLR) were recorded during follow-up. Severity of angina pectoris (CCS classification) and a need for antianginal treatment (beta-blockers, nitrates, calcium channel blockers) at the baseline and at the end of clinical follow-up was recorded.

RESULTS

Follow-up was completed in 49 patients (98%). Mean time of follow-up is 15.4 +/- 2 months (range 12 - 22 months, median 15 months), two patients died (4 %)--one from colon cancer, the other patient died from lung cancer, there was not any cardiac death recorded, two patients (4%) had target vessel revascularization. Estimated 22 months event-free (all-cause death, MI, TLR) survival was (mean +/- SEM) 86 +/- 7%. There was a significant difference in symptom severity--mean grade of angina pectoris at baseline was 1.8 +/- 1.3, at follow-up 1.1 +/- 1.0 (p < 0.05). There was not difference in use of antianginal drugs was same at baseline and at follow-up (1.7 +/- 0.8 vs. 1.7 +/- 0.7). Thirty-five patients (71%) were treated by statins.

CONCLUSIONS

Deferring of coronary interventions of intermediate stenosis based on FFR measurement is safe in a mid-term follow-up. Despite of the same intensity of antianginal treatment there was a significant decrease in symptom severity.

Gas chromatography/mass spectrometry analysis of exhaled leukotrienes in asthmatic patients

BACKGROUND

Leukotriene-like immunoreactivity has been detected in exhaled breath condensate (EBC), but definitive evidence for the presence of leukotrienes (LTs) in this biological fluid is not available. A study was undertaken to determine whether LTC(4), LTD(4), LTE(4), and LTB(4) are measurable in EBC by gas chromatography/mass spectrometry and to quantify exhaled LTs in adults and children with asthma and in control subjects.

METHODS

Twenty eight adults and 33 children with mild to moderate persistent asthma treated with inhaled corticosteroids and age matched healthy controls (50 adults and 50 children) were studied. LTB(4), LTC(4), LTD(4), and LTE(4) in EBC were measured by gas chromatography/mass spectrometry.

RESULTS

LTD(4), LTE(4), and LTB(4) were detectable in all samples. Concentrations of LTC(4) in EBC were either close to or below the detection limit of 1 pg/ml. Median exhaled LTD(4), LTE(4), and LTB(4) concentrations in asthmatic adults were increased 4.1-fold (p<0.001), 1.8-fold (p<0.01), and 2.6-fold (p<0.001), respectively, compared with values in healthy adults. Median exhaled LTD(4), LTE(4), and LTB(4) concentrations in asthmatic children were increased 2.8-fold (p<0.001), 1.3-fold (p<0.001), and 1.6-fold (p<0.001), respectively, compared with those in healthy children. In patients with asthma there was a correlation between exhaled LTD(4) and LTE(4) in both adults (r = 0.87, p<0.0001) and children (r = 0.78, p<0.0001).

CONCLUSIONS

Gas chromatography/mass spectrometry can be used to accurately quantify exhaled LTs which are increased in asthmatic adults and children compared with controls.

[Assessment of speed of an anti-platelet effect after two different doses of acetylsalicylic acid by flocculation]

Acetylsalicylic acid inhibits aggregation of blood platelets through affecting arachidon acid metabolism--a precursor of thromboxan which is a strong platelet aggregation inhibitor. A standard method for measurement of aggregation activity blockade (in percents) of platelet rich plasma is turbidimetric aggregomethry based on spectrophotometric principle. According to results of recent studies administration of acetylsalicylic acid is one of the basic pillars of prevention of thrombotic complications in atherosclerotic arterial disease. Acetylsalicylic acid doses differ from study to study. An aim of our work was to measure speed of two different doses of acetylsalicylic acid.

RESULTS

Level of aggregation activity blockade in samples of platelet rich plasma was measured by aggregometry in 26 healthy volunteers after administration of four inductors of thrombocyte aggregation (arachidon acid, adenosindiphosphate, collagen, and ristocetin). The samples were taken before administration and 120, 240, and 360 minutes after single peroral administration of 100 or 400 mg of acetylsalicylic acid. Samples of plasma were analysed immediately after sampling. Before drug administration there was no aggregation activity in 27.7% of the sample after arachidon acid administration, 28.3% after ADP administration, 21.5% after collagen administration and 25.3% after ristocetin administration. After administration of 400 mg of acetylsalicylic acid and administration of arachidon acid as an inductor 89.9% of the aggregation activity of the sample was blocked after 120 minutes, 89.6% after 240 minutes, and 90.6% after 360 minutes. After administration of adenosindiphosphate as an inductor 71.7% of the aggregation activity of the sample was blocked after 120 minutes, 68.3% after 240 minutes, and 69.9% after 360 minutes. And, after administration of ristocetin as an inductor 64% of the aggregation activity of the sample was blocked after 120 minutes, 66.4% after 240 minutes, and 54% after 360 minutes. Blockade of aggregation activity after collagen administration was not statistically significant. After administration of 100 mg of acetylsalicylic acid and administration of arachidon acid 83.8% of the aggregation activity of the sample was blocked after 120 minutes, 89.2% after 240 minutes, and 89.6% after 360 minutes. After adenosindiphosphate administration statistically significant blockade of aggregation activity was achieved after 360 minutes in the 56.7% of the sample. Also after collagen administration 42.5% of aggregation activity of the sample was blocked significantly after 360 minutes while ristocetin has not proved to influence aggregation in a statistically significant manner.

CONCLUSION

Both doses of acetylsalicylic acid influenced aggregation activity of platelets in a statistically significant manner as soon as after 120 minutes following their peroral administration. However, they had different ability to influence platelets response to alternative ways of activation--by adenosindiphosphate, collagen, and ristocetin. 400 mg dose blocked these ways while 100 mg dose was efficient in blocking these ways after 360 minutes and in case of ristocetin--an inductor used to monitor platelet adhesion ability--100 mg dose has not led to statistically significant blockade at all.

Tissue factor, tissue factor pathway inhibitor and cytoadhesive molecules in patients with an acute coronary syndrome

The tissue factor plays a crucial role in initiating blood coagulation after plaque rupture in patients with acute coronary syndrome. It is abundant in atherosclerotic plaques. Moreover, P-selectin, some cytokines, endotoxin and immune complexes can stimulate monocytes and induce the tissue factor expression on their surface. The aim of the study was to compare plasma levels of the tissue factor, tissue factor pathway inhibitor, P-selectin, E-selectin and ICAM-1 in patients with acute myocardial infarction, unstable angina pectoris, stable coronary artery disease and normal control subjects. In addition, plasma levels of the tissue factor, tissue factor pathway inhibitor, P-selectin, E-selectin and ICAM-1 were measured in the blood withdrawn from the coronary sinus in a subgroup of patients with unstable angina pectoris and stable coronary artery disease in which the difference between concentrations in the coronary sinus and systemic blood was calculated. A significant increase in tissue factor pathway inhibitor plasma levels was detected in patients with acute myocardial infarction (373.3+/-135.1 ng/ml, p<0.01) and unstable angina pectoris (119.6+/-86.9 ng/ml, p<0.05) in contrast to the patients with stable coronary artery disease (46.3+/-37.5 ng/ml) and normal subjects (45.1+/-14.3 ng/ml). The plasma levels of tissue factor pathway inhibitor were significantly increased both in the coronary sinus and systemic blood in the patients with unstable angina pectoris. There was only a non-significant trend to higher plasma levels of the tissue factor in patients with acute myocardial infarction and unstable angina pectoris as compared to the patients with stable coronary artery disease and normal subjects, the values being 129.1+/-30.2 pg/ml, 130.5+/-57.8 pg/ml, 120.2+/-45.1 pg/ml and 124.9+/-31.8 pg/ml, respectively. Plasma levels of soluble P-selectin was only slightly, but non-significantly higher in patients with unstable angina pectoris and stable coronary artery disease (184.2+/-85.4 ng/ml and 201.6+/-67.9 ng/ml, respectively) than in patients with the acute myocardial infarction (157.4+/-88.4 ng/ml) or normal subjects (151.4+/-47.1 ng/ml). The difference in plasma levels of soluble ICAM-1 between the blood withdrawn from the coronary sinus and systemic circulation correlated significantly with the corresponding difference in plasma levels of soluble P-selectin and E-selectin. In conclusion, the tissue factor and the tissue factor pathway inhibitor play a crucial role in the initiation of arterial thrombosis. The tissue factor pathway inhibitor levels are increased both in the systemic blood and in the coronary sinus of patients with the acute coronary syndrome.

[A statistical method for long-term monitoring of selected causes of death]

The death rate statistics belongs to the essential health parameters and it is therefore frequently analysed. Authors suggest reviewing problems, which could be met, and discussing statistical methods in order to make the comparison and analysis of the development as much corresponding to the actual health state of the population as possible. Authors also discuss methods of the "International classification of diseases" and describe methods of direct data standardisation, including estimation of the variability. Using respiratory diseases as an example, authors illustrate the problems of revision of the code system in the "International classification of diseases" and the give examples of numerical evaluation.

Increased risk of traffic accidents in subjects with latent toxoplasmosis: a retrospective case-control study

BACKGROUND

The parasite Toxoplasma gondii infects 30-60% of humans worldwide. Latent toxoplasmosis, i.e., the life-long presence of Toxoplasma cysts in neural and muscular tissues, leads to prolongation of reaction times in infected subjects. It is not know, however, whether the changes observed in laboratory influence the performance of subjects in real-life situations.

METHODS

The seroprevalence of latent toxoplasmosis in subjects involved in traffic accidents (N=146) and in the general population living in the same area (N=446) was compared by a Mantel-Haenszel test for age-stratified data. Correlation between relative risk of traffic accident and a level of anti-Toxoplasma antibody titre was evaluated with the Cochran-Armitage test for trend.

RESULTS

A higher seroprevalence was found in the traffic accident set than in the general population (Chi2MH=21.45, p<0.0001). The value of the odds ratio (OR) suggests that subjects with latent toxoplasmosis had a 2.65 (C.I.95= 1.764.01) times higher risk of an accident than the toxoplasmosis-negative subjects. The OR significantly increased with level of anti-Toxoplasma antibody titre (p<0.0001), being low (OR=1.86, C.I.95=1.14-3.03) for the 99 subjects with low antibody titres (8 and 16), higher (OR=4.78, C.I.95=2.39-9.59) for the 37 subjects with moderate titres (32 and 64), and very high (OR=16.03, C.I.95=1.89-135.66) for the 6 subjects with titres higher than 64.

CONCLUSION

The subjects with latent toxoplasmosis have significantly increased risk of traffic accidents than the noninfected subjects. Relative risk of traffic accidents decreases with the duration of infection. These results suggest that 'asymptomatic' acquired toxoplasmosis might in fact represent a serious and highly underestimated public health as well as economic problem.

[Angiographically marginally significant coronary stenoses--postponement of intervention based on measurement of myocardial fractional flow reserve]

INTRODUCTION

When evaluating angiographically marginal coronary stenoses (i.e. 40-70% reduction of the diameter of the arterial lumen) it is under certain conditions difficult to decide on their actual functional impact. Assessment of the fractional flow reserve (FFR) is a simple method based on assessment of intracoronary pressures during pharmacologically induced hyperaemia. For the severity of stenosis according to previous studies the liminal values is FFR lower than 0.75; furthermore it was proved that intervention of angiographically marginal stenoses with FFR values of 0.75 or more can be safely postponed.

OBJECTIVE

Test the safety of FFR examination and take in a group of patients with marginally severe stenosis further steps according to results of FFR assessment.

MATERIAL AND METHODS

During the period from January to Juky 2000 FFR assessments were made in a total of 34 patients (11 women, 23 men, mean age 62 +/- 12 years) who suffered from marginal stenosis of some coronary vessel. The FFR examination took place under pharmacologically induced hyperaemia after intracoronary adenosine administration.

RESULTS

Measurements were made in a total of 41 stenoses. Only in two a value lower than 0.75 was found. In these patients coronary intervention was implemented; intervention was also made in two patients on account of technical problems and inconsistent results of FFR measurements. A FFR value of 0.75 or less was found in 37 stenoses (90%) and intervention was therefore postponed. Examination and the immediate subsequent course were without complications.

CONCLUSION

According to initial experience FFR examination is a safe, simple and easily reproducible method. Based on the results of assessment and knowledge of the accomplished studies in the group of marginally significant stenoses in a great proportion of patients coronary intervention was postponed.

A case of repeated accidental inhalation contamination of a male subject with 137Cs

Two consecutive incidents of internal contamination occurred within a 13-mo period when a male worker (56 y, 70 kg) briefly entered and stayed (during a breakdown of control apparatus for air contamination) in a radioisotope storeroom with air contaminated by an explosion of old ampules containing 137Cs solution. Monitoring of the first contamination began on day 34 and that of the second one within 1 h after inhalation. According to the two-exponential model, long-term biological half-times of 92 and 93 d were obtained for the first and second contaminations, respectively. The short-term biological half-time for the second contamination was calculated as 3.0 d. The mean value of the fraction of 137Cs excreted in daily urine to that in total excreta was 0.88 for the first contamination and 0.89 for the second one.

High prevalence of HIV risk-behavior and the identification of predictors for sharing injecting materials among young drug users in Prague, Czech Republic

This study is one of the first studies in the Czech Republic evaluating the extent of the HIV epidemic among drug users. Interview data on demographics, drug use, sexual practices, and HIV knowledge and risk perception were obtained from study participants and a saliva sample was obtained for an HIV antibody test. Although the HIV infection rate is low (0.2%), the prevalence of high risk behaviors, such as sharing injecting equipment and unsafe sexual practices, indicate a potential for rapid HIV spread in this high risk population. Preventive measures need to be targeted toward drug users, especially those of younger age and women.

[Health status of the population in six cities in the Czech Republic: prevalence and therapy of various chronic diseases]

BACKGROUND

The aim of the study was to describe health status of the urban middle-age population in six cities of the Czech Republic, which were included into the System of Population Health Survey in Relation to the Environment.

METHODS AND RESULTS

From the population of cities Brno, Ceské Budĕjovice, Hradec Králové, Karviná, Kolín, Ustí nad Labem 400 males and 400 females in the age of 45 to 54 years were included into the study. All respondents filled out a question-form, half of them also underwent a medical check up. Results has shown that 52.8% of males and 51.6% of females had their cholesterol level elevated (> 5.2 mmol/l), 47.3% of males and 38.3% if females had higher blood pressure (SBP > = 140 mmHg and/or DBP > = 90 mmHg) or they were cured of hypertension, 39.4% of males and 22.5% of females were obese. Significant differences were observed in the prevalence of hypercholesterolemia, hypertension and smoking habits among the cities in study. According to the case histories, 55.6% of males and 57.8% of females complained of long-lasting ill-being, 37.0% of males and 45.2% of females were treated for a chronic disease, 13.3% of males and 12.4% of females considered their health during the previous year as bad or very bad. 45.4% of males and 57.9% of females underwent long-term pharmacological treatment, most frequently on a cardiovascular disease. Above described parameters differed significantly among cities in study.

CONCLUSION

In the middle-aged population in six Czech cities the high prevalence of chronic diseases, health troubles and risk factors of chronic disease were found. Though the death rate in CR has been declining, chronic diseases have became a serious problem. Since most of these health problems can be improved by correct regimen, high attention should be given to their prevention.

[In towns there is a higher prevalence of asthmatic symptoms in children than in rural areas]

The authors assessed the prevalence of symptoms of bronchial asthma by means of a standardized questionnaire used in the international survey PEACE (Pollution Effect on Asthmatic Children in Europe). The questions about complaints were addressed to children aged 6-13 years (the questionnaires were completed with the parents assistance). In urban areas 5669 children participated from Prague 5, i.e. 35% of all elementary school children, in Teplice 2489 (21% children), in rural areas: in the Benesov district 5619, i.e. 61% children, in the Prachatice district 1983, i.e. 37% children. The response rate of questionnaires in the urban areas was 86-88%, in rural areas 93%. In urban areas the annual prevalence of wheezing in the chest or dyspnoea or possibly both symptoms was within the range of 3.8-13.8% and differed significantly from the prevalence in rural areas where it was 2.4-3.6%. The most frequent symptom was nocturnal dry cough without a cold (in urban areas 14.1-36.7%, in rural areas 6.0-10.6%). Rural areas differed from urban ones by a lower contamination of the atmosphere, a lower density of the population as well as some parameters caused by a different lifestyle.

[Indicators of progression of HIV infection and their application to therapy]

The authors evaluated in a group of 217 HIV positive patients the mutual relationship of the number of CD4+T lymphocytes and the level of the viral load of HIV RNA. Using correlation analysis evidence was provided of a not very marked negative correlation of the two indicators. As it was assumed that the relationship of the two parameters is influenced by the applied therapeutic procedures which reduce in particular the viral load, the two parameters were evaluated in relation to treatment. The closest relationship of the two investigated parameters was found in the group treated by monotherapy with zidovudine, followed by the group treated with a combination of two preparations (two nucleoside inhibitors of reverse transcriptase). In the group treated by three preparations (two nucleoside inhibitors of reverse transcriptase and a protease inhibitor) the relationship of the two parameters was least close. Investigation of the level of the viral load of HIV RNA and number of CD4+T lymphocytes is of major importance for the introduction of antiretrovirus treatment and selection of a suitable combination of antiretrovirus preparations. It makes it also possible to follow up the effectiveness of this treatment.

[Gunshot wounds of the spine and spinal cord.]

The authors summarize the existing findings on the treatment of gunshot wounds of the spine and spinal cord which in their country have become an important cause of mortality and morbidity. Their own experience prove the findings of the authors, i.e. that the seriousness of the initial neurological condition can be hardly influenced and an urgent surgical decompression does not improve statistical prospects of the correction in any type of neurological deficit either, with the exception of cauda ae-quina syndrome. They point out that occurrence of complications such as infections, liquor fistula or instability is from the statistical viewpoint significantly higher in patients operated on. They discuss the role of a routine antibiotic prophylaxis and corticotherapy.The stability of spine is usually not impaired by gunshot wounds and as a rule it does not reqiure stabilization by implants.Therefore they recommend to consider the occurrence of instability on a caseby-case basis. Key words: penetrating spinal injury, spinal injury.

[Treatment of fractures of the lower cervical spine (C3-C7)]

Spinal surgery dealing with reparation of injury consequences by stabilisation implantates is a relatively new surgical branch. The experience and results at individual departments in Slovakia in this field differ significantly as to their qualitative degree. The Trauma Surgery Department IVZ in Bratislava and the National Rehabilitation Center in Kovácová cooperate since 1989 in a mutual spinal programme. 177 out of 189 patients survived after undergoing a surgical treatment due to the injury of the lower cervical spine performed from 1988 to 1994. 68 patients (Frankel A, B, C) were included into the spinal programme. The authors present the therapeutical results evaluated according to morphologic, neurologic, functional and subjective criteria. The most frequently used stabilizing method is the so-called method of Caspar and the technique of Morscher, the latter being less frequently applied. Both methods are fully secure, causing minimal blood loss, perfectly stable as to the angle and axis. Both techniques enable a sufficient approach to the decompression of the spinal cord. Since they do not demand any additional external rigid fixation, they are excellently tolerated by patients and only minimally restrict movement. (Tab. 2, Fig. 4, Ref. 8.)

[Prevalence of bronchial asthma, chronic bronchitis and allergic rhinitis in a South Moravian District]

In a random sample of 648 adults (18-70 years), representing 95,836 people by age and sex, the prevalence of the above mentioned diseases was assessed. The chi 2-test revealed that the sample of examined subjects did not differ significantly from the distribution of the population as regards age and sex. The prevalence of bronchial asthma was 2.0%, of chronic bronchitis 16.3%, pollen rhinitis 4.5% and non-seasonal rhinitis 4.9%. In asthma the immunological type of the disease predominated markedly. Bronchial hyperreactivity after inhaled histamine was almost five time higher in asthma than in bronchitis (100% and 22.5%).

[The bronchodilator agent, Ventodisk, in the powdered inhalation form without freon is better]

The authors compared the effectiveness and advantages of the powdered inhalation variety of the preparation Ventodisc (Glaxo) with the "classical" dosed inhalation form of Salbutamol (Polfa) in 21 patients with bronchial asthma. During administration of 0.2 mg of the two drugs various conditions (mastering of the inhalation technique, elimination of the action of other drugs and the same time of day when the drug was administered) was respected. Values of ventilation parameters of the central and peripheral respiratory pathways before administration of the drugs did not differ significantly. The powdered form of salbutamol--Ventodisc (Glaxo) had a greater dilatating action than the classical dosed aerosol form--Salbutamol (Polfa) because: 1. in FEV1 values between rest and Ventodisc (1.47 l and 1.73 l) differed significantly, however, after subsequent inhalation of Salbutamol no further significant improvement occurred (1.79 l); 2. when the sequence of stimuli was reversed a significant increase of the FEV1; value occurred after Salbutamol (from 1.50 l to 1.67 l, p < 0.004) but Ventodisc caused a further significant increase (p < 0.0006). The tolerance of both drugs was equal. The powdered inhalation form of Salbutamol (Ventodisc--Glaxo) was better than the "classical" dosed aerosol form of salbutamol (Salbutamol--Polfa) as it had a greater dilatating effect in the central airways and moreover did not contaminate the environment.

Improved spatial and temporal resolution in an apparatus for time-lapse phase contrast ciné micrography of cells in vitro

An apparatus for time-lapse cinemicrography of living animal cells in vitro is described. It has an increased information capacity in comparison with conventional types of equipment in that successful combination of the highest possible spatial resolution with phase contrast microscopy and an improved temporal resolution provided by flash light illumination has been achieved. The interval between exposures of 1/200 s approximately can be reduced to 1/4s using a negative phase-contrast objective of NA 1 . 3. Negative phase-contrast also appeared to be the best technique for imaging of tiny cell surface structures. Thus the new apparatus is suitable for the study of the patterns of cell surface motility in vitro.

A new light microscopic method for the synchronous bidirectional illumination and viewing of living cells in different contrast modes, and/or at different focal levels or magnifications

A new method of light microscopy for the analysis of the behaviour of living cells in vitro exploits two objects for simultaneous image formation, each serving the other as a condenser. Simultaneous viewing from opposite sides allows the specimen to be examined at: (a) two different magnifications, permitting the locomotion of whole cell (groups) to be studied at a low magnification and details of interaction of colliding surfaces at a high magnification; (b) two different focal levels, permitting, for example, details near the substrate surface to be recorded at the same time as information concerning the behaviour of the free, dorsal surface; and (c) two different contrast modes, such as negative and positive phase contrast, and dark and bright field illuminations. These possibilities can be combined, for example, to contrast a high magnification view in negative phase contrast at one focal level with a low magnification image in ordinary brightfield at another focal level in the same living cells.