Cerebellar apparent diffusion coefficient changes in patients with supratentorial ischemic stroke.

OBJECTIVES: To evaluate apparent diffusion coefficient (ADC) in cerebellar subregions in patients with stroke. MATERIALS AND METHODS: The total counts and ADCs were bilaterally measured on cerebellar white matter, gray matters of medial (G1), intermediate (G2), and lateral zones (G3) on SPECT and ADC maps from 20 patients with supratentorial ischemic stroke within the first 48 h and on day 8 after onset. ADCs were also obtained from 15 age-matched controls. RESULTS: Within 48 h, the ADCs were significantly increased bilaterally in the G3, and tended to be increased bilaterally in the white matter and G1, and contralateral G2 compared with controls. On day 8, the ADCs were significantly increased in all contralateral cerebellar subregions and in ipsilateral G1 and G2, and tended to be increased in ipsilateral G3. The ADC value was significantly higher in contralateral than in ipsilateral white matter on day 8. The interhemispheric asymmetry indices (AIs) of ADC and SPECT were significantly associated with each other in G2 and G3 within 48 h, but not on day 8. The AIs of ADC and SPECT were significantly related to each other in the G3 within 48 h and on day 8. CONCLUSIONS: Supratentorial ischemic stroke may cause mild cerebellar vasogenic edema.

CD44 expression and its relationship with MMP-9, clinicopathological factors and survival in oral squamous cell carcinoma.

We investigated the expression of CD44 and MMP-9 in primary oral squamous cell carcinoma (OSCC) and evaluated their association with each other and clinicopathological factors as well as their prognostic value during long term follow up. Histological samples from 138 OSCC patients were immunohistochemically stained for the expression of CD44 and MMP-9. The staining results were compared with conventional prognostic factors and their impacts to patients' prognosis were also studied with survival analyses. Irregular staining of CD44 in tumour cells was associated with poor tumour differentiation (p=0.003), higher clinical stage (III-IV) (p=0.049), and the presence of T3-4 tumour stage (p=0.03). Strong stromal MMP-9 staining intensity was correlated with poor tumour differentiation (p=0.03). In univariate survival analysis irregular staining of CD44 in tumour cells was related to poor disease free and overall survival (p=0.001 and p<0.001, respectively). In multivariate analysis CD44 staining was a significant independent predictor for overall (p=0.03) and disease free survival (p=0.003). MMP-9 expression showed no statistical significance in survival analyses. Strong stromal staining intensity of MMP-9 correlated with irregular staining of CD44 in tumour cells, but had no prognostic significance in the present cohort. However, irregular staining of CD44 predicted more advanced disease and shortened survival of the patients.

Cerebral hemodynamics in human acute ischemic stroke: a study with diffusion- and perfusion-weighted magnetic resonance imaging and SPECT.

Nineteen patients with acute ischemic stroke (<24 hours) underwent diffusion-weighted and perfusion-weighted (PWI) magnetic resonance imaging at the acute stage and 1 week later. Eleven patients also underwent technetium-99m ethyl cysteinate dimer single-photon emission computed tomography (SPECT) at the acute stage. Relative (ischemic vs. contralateral control) cerebral blood flow (relCBF), relative cerebral blood volume, and relative mean transit time were measured in the ischemic core, in the area of infarct growth, and in the eventually viable ischemic tissue on PWI maps. The relCBF was also measured from SPECT. There was a curvilinear relationship between the relCBF measured from PWI and SPECT (r = 0.854; P < 0.001). The tissue proceeding to infarction during the follow-up had significantly lower initial CBF and cerebral blood volume values on PWI maps (P < 0.001) than the eventually viable ischemic tissue had. The best value for discriminating the area of infarct growth from the eventually viable ischemic tissue was 48% for PWI relCBF and 87% for PWI relative cerebral blood volume. Combined diffusion and perfusion-weighted imaging enables one to detect hemodynamically different subregions inside the initial perfusion abnormality. Tissue survival may be different in these subregions and may be predicted.

Multivariate analysis of prognostic factors in 106 patients with malignant glioma.

The aim of this study was to evaluate the outcome and prognostic factors influencing survival in 106 patients with supratentorial malignant gliomas treated with radiotherapy. The study group included 84 patients treated by surgery and post-operative radiotherapy and 22 patients treated by postbiopsy irradiation. Radiotherapy was delivered to the tumour area with a 2 cm margin, the aimed curative dose was 60 Gy in 6-7 weeks. The 60-month overall survival (Kaplan-Meier) was 20%. Following a univariate analysis, younger age (P < 0.001), longer duration of symptoms (P = 0.009), good performance status after radiotherapy (P < 0.001), other than grade 4 histology (P < 0.001) and higher radiation dose (P < 0.001) were associated with better overall survival rates. Multivariate analysis found that age, symptom duration, histology, extent of symptoms and radiation dose were independent prognostic factors influencing survival. In conclusion, conventional radiotherapy of supratentorial malignant gliomas results in survival that is comparable to results from clinical experiments with different fractionation schedules and radiation with chemotherapy or radiosensitisers. To improve the results, new approaches are needed, especially for patients with the poorest prognosis after standard treatment.

Detection of residual tumours in postchemotherapy testicular cancer by FDG-PET.

The aim of this study was to investigate whether 2-(F-18)-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) could reliably detect testicular cancer in patients following chemotherapy. Twenty FDG-PET studies were performed on 15 patients with metastatic seminoma or non-seminoma. Tracer uptake in the PET study was measured by calculating the standardised uptake value (SUV) for the tracer. Nine lesions out of 20 were judged to be positive based on high FDG uptake. Three proved to represent inflammatory changes in non-cancerous tissue. Eleven PET studies were negative. In one of these, viable tumour was found at retroperitoneal lymphadenectomy. The median SUV values of metastatic tumours and benign residual tumours were 2.7 (range 1.6-9.5, n = 10) and 1.7 (range 0.7-5.5, n = 15), respectively. The large overlap of SUVs between these groups was due to the relatively high FDG uptake in inflammatory tissue (median 4.2, range 2.0-5.5, n = 4). The results indicate that FDG imaging of metastatic testicular cancer after chemotherapy has limited value because of a potentially high accumulation of FDG in inflammatory tissues.

Experience in qualitative and quantitative FDG PET in follow-up of patients with suspected recurrence from head and neck cancer.

We evaluated positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in the detection of recurrent head and neck cancer, and compared visual and quantitative interpretation of PET images for their accuracy in the identification of tumour recurrence. Sixty-two FDG PET studies were performed in 56 patients having a total of 81 lesions, which were clinically suspected for recurrent carcinoma of the head and neck. The PET images were interpreted visually, and tracer uptake was quantitated as the standardised uptake value adjusted to body weight (SUV). Sensitivity of visual interpretation of the PET images for the presence of malignancy ranged from 84 to 95%, and specificity from 84 to 93%, respectively, depending on the selected scheme for grading of the lesions. Malignant lesions accumulated significantly more FDG than the benign ones (the median SUVs were 6.8 and 3.3, respectively, P<0.001). However, there was a wide overlap of the FDG uptake values between these two groups. Hence, the highest accuracy of quantitative analysis in correct identification of tumour recurrence (75% at Receiver Operating Curve analysis) was inferior to that of visual analysis (89%). FDG PET is feasible for the detection of recurrent head and neck cancer. Although quantitation of FDG uptake using SUV shows significantly higher tracer concentrations for malignant than benign lesions, the wide overlap of individual SUVs between these two groups is a serious concern in diagnostic evaluation. Therefore, in clinical practice it may be preferable to identify the presence of tumour recurrence within this patient group by qualitative interpretation of the PET images.

Quantitative assessment of protein content in irradiated human skin.

PURPOSE: Radiation-induced fibrosis is a common late reaction of radiation therapy. Due to a lack of feasible noninvasive techniques to assess this reaction, the long-term development of radiation fibrosis is not well described. In order to develop quantitative means for the purpose, subcutaneous fibrosis of breast cancer patients after postmastectomy radiotherapy was evaluated by clinical scoring and a new technique based on dielectric properties of the skin. METHODS AND MATERIALS: Dielectric properties of biological tissues at radiofrequencies are principally determined by tissue water content. The major skin components are proteins, proteoglycans, and water either free or bound to the surface of proteins and proteoglycans. Since the MR studies have shown that bound water is tightly attached onto the surface of collagen, a dielectric measurement sensitive to bound water could be related to the protein content. Therefore, the dielectric constant of human skin was measured in vivo with an open-ended coaxial probe at electromagnetic (EM) frequencies in the range of delta-dispersion. Since the in vitro experiments with protein-water solutions have indicated that the slope of the dielectric constant vs. the EM frequency is a measure of the protein concentration, a respective slope was determined with irradiated skin of 14 breast cancer patients 2 years after postmastectomy radiotherapy at 63, 100, 300, and 500 MHz. Irradiated skin sites were clinically scored for subcutaneous fibrosis using a scale: none, slight, moderate, or severe fibrosis. RESULTS: A statistically significant correlation was found between the slope and the clinical score of subcutaneous fibrosis at 63, 100, and 300 MHz but not at 500 MHz. The correlation was best at 100 and 300 MHz. CONCLUSIONS: Considerable changes in the dielectric constant of the irradiated skin were found. The correlation between the dielectric constant and clinical score suggests that this novel technique is a potential tool for the follow-up and quantitative assessment of radiation-induced subcutaneous fibrosis.

Radiotherapy treatment planning and long-term follow-up with [(11)C]methionine PET in patients with low-grade astrocytoma.

PURPOSE: To evaluate the feasibility of [(11)C]-methionine positron emission tomography (MET PET) in radiotherapy (RT) treatment planning and long-term follow-up in patients with low-grade glioma. PATIENTS: Thirteen patients with low-grade astrocytoma and 1 with anaplastic astrocytoma underwent sequential MET PET and magnetic resonance imaging (MRI) before and 3, 6, 12, and 21-39 months after RT, respectively. Ten patients were studied after initial debulking surgery or biopsy and 4 in the recurrence phase. METHODS: A total of 58 PET scans were performed. After transmission scanning, a median dose of 425 MBq of MET was injected intravenously and emission data was acquired 20 min after injection for 20 min. The uptake of MET in tumor area was measured as standardized uptake value (SUV) and tumor-to-contralateral brain SUV ratios were generated to assess irradiation effects on tumor metabolism. Functional imaging with PET was compared with concurrent MRI in designing the RT planning volumes and in assessment of response to RT during a median follow-up time of 33 months. RESULTS: In 12 patients (86%), tumor area was clearly discernible in the baseline PET study. In the remaining 2 patients with a suspected residual tumor in MRI, PET showed only a diffuse uptake of MET interpreted as negative in the original tumor area. In the dose planning of RT, MET PET was helpful in outlining the gross tumor volume in 3 of 11 cases (27%), whereas PET findings either coincided with MRI (46%) or were less distinctive (27%) in other cases. In quantitative evaluation, patients with a low tumor SUV initially had significantly better prognosis than those with a high SUV. Tumor-to-contralateral brain uptake ratios of MET discriminated well patients remaining clinically stable from those who have since relapsed or died of disease. CONCLUSION: Quantitative MET PET has prognostic value at the time of initial treatment planning of low-grade glioma. Some patients may benefit of RT volume definition with MET PET, which seems to disclose residual tumor better than MRI in selected cases. Stable or decreasing uptake of MET in tumor area after RT during follow-up seems to be a favorable sign.

Combined SPECT and diffusion-weighted MRI as a predictor of infarct growth in acute ischemic stroke.

UNLABELLED: In acute ischemic stroke, the infarcted core is surrounded by a zone of tissue that has decreased perfusion. Some of this tissue may be salvaged by prompt, effective treatment. Diffusion-weighted MRI is sensitive in detecting the infarcted tissue, whereas SPECT also detects the hypoperfused tissue around the infarcted core. We studied the potential of combined diffusion-weighted MRI and SPECT to predict infarct growth and clinical outcome in patients not receiving thrombolytic treatment. METHODS: Sixteen patients with acute stroke were examined consecutively with diffusion-weighted MRI and 99mTc-ethyl cysteinate dimer (99mTc-ECD) SPECT within 24 h of the onset of symptoms. Follow-up diffusion-weighted MRI was performed on the second day and after 1 wk. The volumes of infarcted and hypoperfused brain tissue were measured from diffusion-weighted MRI and SPECT, respectively. The volume difference between the hypoperfused and infarcted tissue on the first day was compared with the possible increase in infarct volume during the follow-up. Each patient's neurologic status was assessed with the National Institutes of Health Stroke Scale (NIHSS). RESULTS: The volume of infarcted tissue increased from 48 +/- 54 cm3 (mean +/- SD) on the first day to 88 +/- 93 cm3 on the second day (P = 0.001) and to 110 +/- 121 cm3 at 1 wk (P = 0.001). The volume of hypoperfused tissue on the first day was significantly greater than the infarct volume (102 +/- 135 cm3; P = 0.001). The volume difference between the hypoperfused and infarcted tissue on the first day correlated significantly with the infarct growth between the first day and 1 wk (r = 0.71; P < 0.01). Between the first day and 1 wk, the increase of the infarct volume correlated significantly with the change in the NIHSS (r = 0.54; P < 0.05). CONCLUSION: A large hypoperfusion zone around the infarct core in the acute phase of ischemic stroke predicts the infarct growth during the first week, and this correlates significantly with the change in the neurologic status of the patient. Combined diffusion-weighted MRI and SPECT performed within 24 h after the onset of symptoms can be useful in the evaluation of acute stroke to predict infarct growth.

Evaluation of early response to radiotherapy in head and neck cancer measured with [11C]methionine-positron emission tomography.

PURPOSE: To evaluate whether positron emission tomography (PET) with carbon-11-methionine (MET) can be used for detection of early response to external beam radiotherapy (RT) in untreated head and neck cancer using locoregional control and survival as study endpoints. MATERIALS: Fifteen patients with head and neck cancer underwent a MET PET study before RT and after a median dose of 24 Gy. Fractionation was standard (n = 6) or hyperfractionated (n = 9), and 13 out of 15 patients had planned surgery after RT. SUV was calculated for primary tumor (n = 13) or largest lymph node metastasis in two patients of whom one had his primary excised before study enrollment and one presented with unknown primary tumor syndrome. METHODS: Attenuation corrected PET scans acquired 20-40 min from tracer injection were used for evaluation of MET uptake in tumors. A quantitative MET uptake index was expressed as standardized uptake value (SUV) or SUV(lean) (corrected for lean body mass). The PET results were correlated with clinical follow-up data. The median follow-up time is currently 28 months (range 22-34). RESULTS: A total of 13 primary tumors and 12 metastatic lymph nodes were visually identified in MET PET. In the first PET study the median SUV in tumor was 8.6 (range, 5.5-14.0). In the second PET study performed during RT the median SUV decreased to 5.7 (range, 3.1-8.2, P = 0.001). Two out of 15 patients showed no radiation-induced decrease in SUV. The median tumor SUV ratio of patients remaining in local control (CR) after RT was 0.7 (range 0.6-0.8, n = 6), and that of relapsing patients similarly 0.7 (range 0.5-1.0, n = 9, NS). The SUV ratio was not associated with survival time. The MET uptake of submandibular salivary glands decreased in all patients during the first two or three weeks of RT (P = 0.03). CONCLUSIONS: MET uptake in tumor shows a significant decrease during the first two to three weeks of RT of head and neck cancer. It appears that the rate of decrease in tracer uptake is comparable in relapsing patients and those who remain locally controlled and thus the use of MET PET for prediction of response to RT is limited.

Radiobiological depth of subcutaneous induration.

The incidence of subcutaneous induration in 23 breast cancer patients with postmastectomy radiotherapy was investigated. The patients were treated with three different radiotherapy schedules 7. 9-9.8 years ago. The incidence was correlated with the biological effective dose (BED) at different depths from the skin surface and a best fit was obtained using an alpha/beta ratio of 2 Gy. The most representative depth at which to assess dose for subcutaneous induration was 2 mm which is near the subcutaneous fat/dermis interface.

A dielectric method for measuring early and late reactions in irradiated human skin.

BACKGROUND AND PURPOSE: To measure the dielectric constant of irradiated human skin in order to test the feasibility of the dielectric measurements in the quantitation of acute and late radiation reactions. MATERIALS AND METHODS: The dielectric constant of irradiated breast skin was measured at an electromagnetic frequency of 300 MHz in 21 patients during postmastectomy radiotherapy. The measurements were performed with an open-ended coaxial line reflection method. The irradiation technique consisted of an anterior photon field to the lymph nodes and a matched electron field to the chest wall using conventional fractionation of five fractions/week to 50 Gy. Fourteen out of the 21 patients were remeasured 2 years later and the skin was palpated for subcutaneous fibrosis. RESULTS: At 5 weeks the dielectric constant had decreased by 31 and 39% for the investigated skin sites of the photon and electron fields, respectively. There was a statistically significant inverse correlation between the mean dielectric constant and the clinical score of erythema. An unexpected finding was a decrease of the dielectric constant of the contralateral healthy skin during radiotherapy. Two years later a statistically significant positive correlation was found between the dielectric constant at the irradiated skin sites and the clinical score of subcutaneous fibrosis. CONCLUSIONS: Dielectric measurements non-invasively yield quantitative information concerning radiation-induced skin reactions.

Versican expression in pharyngeal squamous cell carcinoma: an immunohistochemical study.

AIMS: To study the expression of versican, a large proteoglycan involved in repressing adhesion between cells and the extracellular matrix in pharyngeal squamous cell carcinoma (PSCC), and its relation to the expression of p53 and catenins, histological differentiation, clinical data, and prognosis. METHODS: For the retrospective survey, primary tumours for analyses were obtained from 118 patients diagnosed with PSCC of the oropharynx or hypopharynx. The immunohistochemical expression of versican was studied and was related to the expression pattern of p53 and catenins, in addition to clinical data and survival. RESULTS: In the primary tumours, strong stromal versican expression was graded as low in 59 (50%) and high in 59 (50%) cases. In addition, intracellular versican staining was seen in nine (8%) tumours. In local lymph node metastases, strong stromal versican staining was significantly more frequent compared with the primary tumours (p = 0.018). Strong stromal versican staining was more frequently seen in less advanced tumours (p = 0.015). There was no association between versican expression and the other investigated variables (p53, catenins, TNM status, and histological grade). Neither stromal nor intracellular versican expression predicted overall survival in these patients. CONCLUSIONS: Versican was more strongly expressed in the stroma of local metastases and in the earlier stages of disease in PSCC. However, versican expression was not an independent prognostic factor in this entity.

Mass spectrometric studies on small open-chain piperazine-containing ligands and their transition metal complexes.

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was used to characterize the complexes formed between open-chain piperazine-containing ligands and transition metal salts (Cobalt, Copper, Zinc, and Cadmium as chlorides, nitrates, and acetates). Only single-charged complexes were observed, formed of one ligand (L) and mainly one metal ion (M). Since the net charge of the complexes was one, a counterion (X) was attached to some of the complexes, with formation of [L + M + X]+ complexes, and a proton was lost from others, as in [L - H + M]+ complexes. In most cases the composition of the complexes was more dependent on the ligand than the metal salt. Collision-induced dissociation measurements showed that complexes with related composition often differed in structure, or that interactions between the ligand and the metal ion were not alike. The metal ion influenced considerably the fragmentation pathways of the ligands, so that the fragmentation products could be used to deduce the binding sites of the metal. The variations observed in fragmentation behavior of complexes possessing the same ligand but different metal ions can mostly be explained by the ionic radius and electronic configuration of the metal ion. The results indicated a preference of the piperazine ring of the coordinated ligand for the boat conformation.

Reduced expression of hyaluronan is a strong indicator of poor survival in oral squamous cell carcinoma.

Several malignant tumours accumulate hyaluronan (HA), a matrix component suggested to promote cancer cell growth and migration. The expression and prognostic value of HA was analysed in a cohort of 151 oral squamous cell carcinoma (SCC) patients with adequate archival tumour material and follow-up data. The tumour samples were stained using a biotinylated HA-specific probe. Normal squamous epithelium showed a strong and homogeneously distributed staining for HA. The most superficial layers were HA-negative. In moderate (n=11) and high grade (n=16) dysplasias an irregular HA staining was observed around invasive cancer. Malignant transformation in oral squamous cell epithelium changed the staining toward irregular with focal reduction of HA. The well (n=92) or moderately differentiated (n=47) carcinomas had a strong HA staining intensity. In poorly differentiated tumours (n=12) the HA staining was weaker and mainly intracellular. The stromal tissue showed usually moderate (n=69) or strong (n=67) HA staining intensity with no statistically significant correlation with the degree of tumour differentiation. At the end of the follow-up (median 52 months) 66 (43%) patients had died because of an oral SCC. A significant difference in overall survival (OS) and disease free survival (DFS) (P=0.0002 and 0.0020, respectively) was noticed between the patients with the different epithelial staining patterns for HA. The reduction of HA staining was associated with poor survival. In Cox's multivariate analysis HA staining was a significant independent predictor of OS (P=0.011) and DFS (P=0.013). These results suggest that HA is a prognostic marker in oral squamous cell carcinoma.

Farmers' occupational health programme in Finland, 1979-1987.

At the beginning of 1985, the National Board of Health in Finland issued directives for the initiation of farmers' occupational health services in municipal health care centres. The directives were based on the evaluation study on farmers' occupational health services in Finland. The main aim of this study is to analyse the current problems of the farmers' occupational health care system and to analyse how effective the system is. The efficiency of the occupational health services has been surveyed with postal inquiries twice, first in 1982 and later in 1986. The farmers' knowledge of appropriate means for reducing hazardous exposures had improved significantly since the initiation of the occupational health services. The effect of the occupational health services was evident particularly in the more effective use of personal safety devices. The limited resources at the municipal health care centres form the main obstacle in the provision of occupational health services for all farmers who would like to have them. 25-35% of the farmers in Finland (total 45,000 farmers) are willing to participate in the occupational health care system. Participation is voluntary for self-employed farmers.

Detection of human papillomavirus (HPV) DNA in oral squamous cell carcinomas by in situ hybridization and polymerase chain reaction.

A series of 156 formalin-fixed, paraffin-embedded biopsies from 40 patients with surgically-treated oral squamous cell carcinomas was analysed for the presence of human papillomavirus (HPV) infection by histopathological evaluation, in situ DNA hybridization and polymerase chain reaction (PCR). Epithelial changes suggesting a HPV lesion within, or adjacent to, the carcinoma lesions were found in 16 out of 40 patients (40%). Morphological signs of a flat HPV lesion were found in four cases (10%), those of inverted type in three cases (7.5%), and those of papillary type in nine cases (22.5%). HPV DNA was demonstrated in one of the lesions by in situ hybridization with biotin-labelled DNA cocktail probe containing HPV types 6, 11, 16 and 18. With the PCR technique, samples from 11 (27.5%) of the 40 patients proved to contain HPV DNA. Of these, HPV 6 was demonstrated in one case, HPV 16 in ten cases and HPV 18 in one case. HPV DNA was exclusively detected in the biopsies showing carcinoma tissue or its adjacent precancer lesions. No viral DNA was found in the biopsies derived from the tumour-free resection margins. These results provide further evidence to support the concept of HPV involvement in the aetiology of oral squamous cell carcinomas, most probably acting synergistically with other carcinogens.

Measurement of dielectric properties of subcutaneous fat with open-ended coaxial sensors.

A three-layer model of stratum corneum, epidermis/dermis and subcutaneous fat has been developed for the capacitance of an open-ended coaxial line in contact with human skin. Applying the model, the electrical properties of subcutaneous fat can be calculated from skin dielectric measurements with three probes of different sizes. The three-layer model is based on a variational formula for the capacitance of the coaxial probe. An accurate approximation for the dielectric constant of the multilayer cutaneous structure is presented for the inverse problem of solving the dielectric constants of various layers. The method was tested at 300 MHz with breast cancer patients who often have radiotherapy-induced late alterations in the structure of subcutaneous fat due to the development of subcutaneous fibrosis. Measurements from 206 sites yielded a good agreement between the dielectric constant of subcutaneous fat and the clinical score for subcutaneous fibrosis.

Penetration of electromagnetic fields of an open-ended coaxial probe between 1 MHz and 1 GHz in dielectric skin measurements.

An open-ended coaxial probe is often used for investigating the dielectric properties of biological tissues. The present study indicates that in addition to the probe size, the penetration of the electromagnetic (EM) fields of an open-ended coaxial probe in contact with the skin is dependent on the applied frequency between 1 MHz and 1 GHz. At high frequencies, above 100 MHz, the measured dielectric parameters are functions of the dielectric properties of different cutaneous layers and subcutaneous fat. At lower frequencies, less than 10 MHz, the measurement is mainly dependent on the dielectric properties of superficial structures of the skin. The reason for this is that the probe, the surface of the skin, mainly stratum corneum, and underlying skin form a capacitance where the stratum corneum with low water content lies between the well-conducting dermis and the probe. The situation is equivalent to the frequency-dependent Maxwell-Wagner interfacial polarization. This result is verified by experimental dielectric measurements and with human skin in vivo.

Asymmetry in the nasal mucociliary transport rate.

Several methods have been devised for measuring the nasal mucociliary transport rate (N-MTR), but only one side of the nose has usually been studied. This study was conducted to determine whether there are side-to-side differences in N-MTR. A radioisotopic method was used to investigate 185 patients with various respiratory symptoms. Bilateral measurements were performed in the 111 patients with an N-MTR of under 7 mm per minute. In 16 healthy control subjects, the N-MTR ranged from 5.0 to 14.6 mm per minute (mean: 7.8 mm per minute) in the better nostril and from 1.2 to 11.0 mm per minute (4.3 mm per minute) in the poorer nostril (P<.001). In the 111 patients, the N-MTR ranged from 0.0 to 12.0 mm per minute (3.5 mm per minute) in the better nostril and from 0.0 to 9.5 mm per minute (1.7 mm per minute) in the poorer nostril (P<.001). In the control subjects, the mean N-MTR was better (P=.011) in the decongested nostril. Even when the N-MTR was less than 5 mm per minute on the first measured side, it was normal on the opposite side in 18.9% of patients and in 18.8% of control subjects. The author concluded that if the N-MTR is impaired in one nostril, it should also be measured in the opposite nostril.