Proton relaxation in a multicompartmental system with exchange, simulating human tissue

The proton magnetic resonance behaviour of human tissue was simulated with a numerical model in which the resonating nuclei were assumed to belong to five different compartments of defined relative sizes and with distinct relaxation properties. Effects of various proton exchange rates between the compartments were included in the model. The time evolution of longitudinal and transverse macroscopic magnetizations was calculated. Applications of this model in magnetic resonance imaging are discussed.

Affinity and efficacy of racemic, (+)-, and (-)-methacholine in muscarinic inhibition of [3H]-noradrenaline release

The right postganglionic sympathetic nerves of rat isolated perfused hearts (previously loaded with [3H]-noradrenaline) were stimulated electrically with 10 trains of 10 pulses at 10 Hz. The inhibition by methacholine of stimulation-evoked [3H]-noradrenaline overflow into the perfusate (determined in the presence of corticosterone, desipramine, phentolamine, and propranolol) was taken as a measure for activation of presynaptic muscarinic receptors. The evoked [3H]-noradrenaline overflow was inhibited by (+)-, racemic, and (-)-methacholine in a reversible and concentration-dependent manner. The concentration causing 50% inhibition (IC50) was 0.1, 0.26, and 65 microM, respectively, resulting in an isomeric potency ratio IC50 (+)/IC50(-) of 650. The dissociation constant KA of the (+/-)- or (+)-methacholine-presynaptic receptor complex was determined after fractional receptor inactivation according to Furchgott & Bursztyn (1967) with phenoxybenzamine or propylbenzilylcholine mustard as irreversible antagonists of muscarinic receptors. KA for (-)-methacholine was estimated according to Mackay (1966). KA of (+)-, (+/-)-, and (-)-methacholine were 2.5, 4 and 440 microM, resulting in an isomeric affinity ratio KA (+)/KA(-) of 180. The discrepancy between the isomeric IC50 ratio and the isomeric KA ratio is explained by a higher intrinsic efficacy of the (+)-enantiomer compared to the (-)-enantiomer. Thus, (+)-methacholine has to occupy fewer receptors to induce a given inhibition of release than its antipode as revealed by a plot of fractional receptor occupancy vs response. The results show that, in the effector system of presynaptic muscarinic inhibition, methacholine enantiomers differ greatly not only in affinity for the receptor, but also to some extent in the efficiency of signal transmission, and both parameters contribute to the high isomeric potency ratio. The activity of the racemate is fully accounted for by the activity of the (+)-enantiomer.

A new monooxygenase product from 7-ethoxycoumarin and its relation to the O-dealkylation reaction

The widely used fluorometric microsomal monooxygenase test for 7-ethoxycoumarin O-dealkylation was reinvestigated with regard to other possible hydroxylation products. By HPLC-analysis no beta-hydroxylation of the ethyl group and no 8-hydroxylation could be detected. Only a small percentage of 6-hydroxylation occurred, but as a new major metabolite 7-ethoxy-3-hydroxycoumarin was found in quantities depending on the microsomal preparation used. The ratio of O-dealkylation to 3-hydroxylation varied according to species, induction, buffer and pH, suggesting that different isozymes of cytochrome P450 were involved. The isozyme mainly responsible for 3-hydroxylation exhibited a great dependence on cytochrome b5 as the donor for the second electron. The fluorometric test does not include 3-hydroxylation due to the virtual absence of an emission spectrum above 450 nm.

Radioprotection of the kidney with degradable microspheres. A pilot study in the dog with repeated irradiation

The left kidney of 9 dogs was irradiated daily for three days with 300 kVp X-rays. Radioprotection was attempted in 5 of the kidneys by administration of degradable microspheres in the renal artery, immediately before irradiation. Protected kidneys received 3 X 8 or 3 X 12 Gy in midplane dose, unprotected kidneys 3 X 5.2 or 3 X 8 Gy. A protective effect due to induced hypoxia could be demonstrated in creatinine clearance, which was significantly higher in protected than in unprotected kidneys at 7 - 13 weeks after irradiation.

Evidence for a propulsive function of the migrating myoelectric complex in rats

In order to investigate the relation between myoelectric activity and the transport of small bowel luminal contents, recordings of migrating myoelectrical complexes (MMCs) were combined with studies of the propulsion of a bile-excreted radioactive test substance. At laparotomy, rats were provided with three pairs of bipolar electrodes, sewn to the seromuscular layer of the small bowel 15, 30 and 45 cm distal to the pylorus. After recovery for 1 week MMCs were recorded with the animal fasted for 18 h and in light barbiturate anesthesia. Concurrently, the bile-excreted radiopharmaceutic, 99mTc-Solco-HIDA, was infused intravenously. At the end of the experiment the rats were sacrificed and the distribution of 99mTc activity was recorded from the excised bowel specimen. In 12 animals with a typical MMC activity recurring every 20 min, the small bowel radioactivity was distributed into discrete portions, separated by fairly long empty segments. In 6 animals the experiments were terminated when an MMC activity front had reached one of the electrodes and in all, a portion of radioactivity was found to be located immediately distal to the position of that particular electrode. 6 control animals were killed when about 10 min had elapsed since the MMC front passed one of the electrode sites. In all these cases the electrode position was found to correspond to empty bowel segments. These data obtained from animals with permanent electrodes but an otherwise intact small bowel strongly support the notion that MMCs result in propulsion of luminal contents.

Morphologic and histochemical studies on the differing radiosensitivity of ductular and acinar cells of the rat submandibular gland

The submandibular glands of male rats were exposed to 50 Gy X-irradiation as a single dose, with or without pre-treatment with either alpha-adrenergic agonists (noradrenaline, phenylephrine) or a cholinergic antagonist (atropine). The effects were analyzed by morphometric, cytochemical and biophysical methods. When X-irradiated without drug pre-treatment, many serous epithelial cells of the intralobular convoluted ducts displayed morphologic evidence of irreversible radiation damage, in contrast to neighbouring mucous and other cells which were unaffected. The effect was maximal 96 h after irradiation. Serous cells from animals irradiated after pre-treatment with atropine showed much more wide-spread injury than those of animals exposed to X-irradiation only. In contrast , serous cells suffered considerably less damage if their secretory granules had been depleted 1 or 2 h before irradiation with either noradrenaline or phenylephrine. Other epithelial cells showed no modulation of their slight radioresponsiveness by these drugs. The observations were substantiated by morphometry of three cell types: (a) mucous cells, (b) non-granulated serous and intralobular striated duct cells, and (c) granulated serous cells. The findings suggest that the striking radiosensitivity of salivary gland serous epithelial cells is linked to their content of secretory granules. These granules are rich in heavy metals, as demonstrated cytochemically with the sulphide silver method (SSM). Using particle-induced X-ray emission ( PIXE ) spectroscopy, the principal metals were shown to be Zn, Mn and Fe. It is conceivable that membranes which enclose organelles rich in metals with the ability to form redox systems (e.g. Fe2+ in equilibrium Fe3+) show enhanced sensitivity to radiation damage due to the metal-catalyzed induction of lipid peroxidation by ionizing radiation. Disruption of secretory granules would be expected to release lytic enzymes into the cell sap, resulting in autolysis. This hypothesis is supported by the findings that atropine--which increases the number of granulated serous cells--enhances radiosensitivity, while noradrenaline and phenylephrine--which cause degranulation of serous cells--decrease radiosensitivity.

Variance measurements with two semiconductor dose detectors

Variance measurements were performed with pairs of semiconductor detectors of different ionization volumes in continuous and pulsed radiation fields. By a statistical analysis the relative variance of the detector was separated from that of the accelerator. The relative variance of the detector signal was shown to be correlated to the detector volume and to the dose per pulse. From the measurements the number of events per pulse within the detector volume was estimated and the number of pulses needed to have a reading with a given precision was estimated.

Ellipsoidal body phantom for evaluation of CT scanners

A phantom for study of uniformity, artifacts from dense structures, and consistency in pixel values was constructed. On-site studies of eight computed tomographs belonging to the second, third, and fourth generations showed that the phantom was appropriate for such measurements. The results indicate certain inherent shortcomings in some of the present designs.

Effects of a fatty meal on small bowel propulsion in intact and vagotomized rats

The mechanisms by which a fatty meal alters small bowel motility was studied in rats. The fatty meal (3 ml soya bean emulsion) was infused via a permanent gastric catheter and, simultaneously, a bile-excreted radiopharmaceutic, via a central venous catheter. After infusion for 1 h the radioactivity along the small bowel was measured from the excised bowel specimen. In fasting animals an 'interdigestive' pattern was found, characterized by the distribution of small bowel contents in well-separated portions. After administration of the fat meal, a different ('postprandial') type of transit was found, characterized by a continuous distribution of radioactivity along the small bowel. In vagotomized animals the chosen fat meal did not induce a postprandial pattern but instead the small bowel retained its interdigestive transit mode. However, in intact animals pretreated with atropine or naloxone, the fatty meal intragastrically resulted in an ordinary postprandial transit pattern. Thus, the effect of the surgical vagotomy seems to be mediated by interruption of noncholinergic, nonenkephalinergic neurons.

Effects of neurotensin on small bowel propulsion in intact and vagotomized rats

The effects of intravenous infusion of neurotensin on small bowel motility was studied in conscious rats. During 1 h a standardized test meal of glucose, polyethyleneglycol (PEG) 3000, phenol red and 125I-labelled polyvinylpyrrolidone was administered via a permanent gastric catheter and simultaneously the bile-excreted radio-pharmaceutic 99Tcm-Solco-HIDA was infused intravenously. Immediately after the infusions the gastrointestinal specimen was excised and examined for distribution of radioactivity. Both doses of neurotensin (0.1 and 0.3 microgram . kg-1 . h-1) resulted in an increase in the neurotensin-like immunoreactivity (NTLI) of plasma to levels similar to that found after a fatty meal. Concurrently the small bowel transport pattern was changed from an interdigestive state to one similar to that found after a meal. In animals not receiving the gastric test meal, neurotensin (0.1-0.5 microgram . kg-1 . h-) had no effect on motility. Infusion of the gastric test meal alone did not change the interdigestive motility or the NTLI value. This indicates that the presence of gastric infusates potentiates the effect of neurotensin on small bowel motility. The motility response to neurotensin did not differ between intact and vagotomized animals. This contrasts to earlier findings that the small bowel motility response to a fatty meal is dependent on intact vagal function. Thus, a difference in the mechanism responsible for the motility responses between a fatty meal and neurotensin exists. In view of this finding it seems reasonable to assume that neurotensin cannot be the only factor responsible for the shift in motility found after a fatty meal.

Histopathological malignancy grading and familiality in an unselected series of 1303 women with breast carcinoma

Histopathological characteristics were studied in 1303 women consecutively diagnosed as having breast cancer. They comprised a total material from a defined geographical area. The significance and distribution of malignancy grades according to Ackerman's system were evaluated in this unselected material. Their relationships with other morphological characteristics and with the occurrence of axillary node metastases with or without periglandular growth were appraised. These characteristics were also related to the familial occurrence of breast cancer. The distribution according to the Ackerman grading was: type I 39 cases (3%), type II 75 (6%), type III: 2 95 (7%), type III:1 793 (61%) and type IV 301 cases (23%). The degree of differentiation (partly by definition) correlated highly significantly with the malignancy grading. Axillary lymph nodes were available for histopathological examination in 844 cases. In malignancy types I and II there were no lymph node metastases, in type III:2 2%, in III:I 40% and in type IV 77%. Periglandular growth was found only in type III:I and IV--in 9 and 59%, respectively. Familial occurrence of breast cancer was confirmed in 19% of the patients. Familial and non familial cases did not differ significantly with respect to the distribution of malignancy grades, degree of differentiation, grade of cell polymorphism or frequency of lymph node metastases.

Fine structure and function of interrenal (adrenocortical) cells of dexamethasone-treated trout (Salmo fario L.)

The ultrastructure of the interrenal (adrenocortical) cells of trout (Salmo fario L.) was studied after dexamethasone treatment. A procedure for identifying and isolating interrenal tissue fragments from the surrounding head kidney tissue prior to their preparation for electron microscopy is described. The peripheral plasma cortisol concentrations were measured in order to evaluate the steroidogenic activity of this tissue. The interrenal cells of control animals contain numerous mitochondria with tubular cristae, and a well developed and highly organized smooth endoplasmic reticulum (SER). The scarcity, or absence, of lipid droplets contrasts markedly with the abundance of SER. Treatment with dexamethasone results in a decrease steroidogenic activity of the interrenal cells, as indicated by the fall in plasma cortisol concentrations. The interrenal cells are small, but still contain numerous mitochondria. The SER is poorly developed, but masses of densely intermeshed smooth cisternae subsist. Lipid droplets do not accumulate in these cells; this peculiarity is discussed in connection with the virtual absence of liposomes in teleost interrenal cells.

Perceptibility of experimental and clinical lesions in the CT image with and without image processing

The Ohio-Nuclear Delta 50 FS whole-body CT scanner and image filtering programs FI and SP:SMOOTH provided with the equipment were used to investigate how the perceptibility in the CT image of artificial lesions in a phantom and of liver lesions in patients was influenced by different reconstruction diameters, radiation doses and section thicknesses and by image filtering and different conditions of viewing. The perceptibility of both artificial and clinical lesions was considerably improved, especially in scans with a low radiation dose, when optimum viewing conditions and image filters were used.

Kidney radioprotection by temporary hypoxia. Experiments with degradable microspheres

Deep hypoxia protects biological tissue against ionizing radiation. By intra-arterial injection of degradable starch microspheres the renal circulation was temporarily blocked in unilaterally nephrectomized rats. The induced hypoxia was utilized for protection of the kidney against single doses of high-voltage X-rays. Renal function and survival date were compared between animals protected by hypoxia and non-protected animals. The survival rate of the former animals exceeded that of the latter by a factor of 1.6. All irradiated animals showed a lower glomerular filtration rate, Hippuran clearance and urine osmolarity than non-irradiated controls. Surviving, protected animals irradiated with 42 Gy and 52 Gy showed a glomerular filtration rate of about 0.5 ml/min and a Hippuran clearance of about 2 ml/min, whereas all non-protected animals irradiated with 42 Gy died.

Computed tomography, ultrasonography and gamma camera scintigraphy after renal transplantation

In routine postoperative observations on 31 transplanted kidneys, computed tomography (CT), ultrasonography (US) and gamma scintigraphy (GS) were compared with respect to diagnosis of abscess or lymphocele in the vicinity of the transplant, rejection and outflow obstruction. The results showed that US was the most reliable procedure for detecting fluid-filled cavities. In cases of graft rejection, GS was of most value. In demonstrating outflow obstruction, there was no definite difference between the three methods.

Bilateral carcinoma of the breast. Epidemiology and histopathology

A history of previous carcinoma in the contralateral breast was found in 66 of 1351 women (5%) consecutively diagnosed as having breast carcinoma. The mean time interval between the diagnosis of the first and second tumour was 10.0 years (range 0-37 years); 63 of the tumours were metachronous. No significant differences were found between the first and the second carcinoma with respect to the Ackerman malignancy grading or the frequency of axillary node involvement. High risk groups for bilateral disease could not be defined on the basis of information about familial occurrence, parity, age at first birth, or malignancy grade.

Noise and noise texture in CT images before and after post-processing

Two homogeneous water phantoms were recorded under various CT scanner settings, and the reducing effect of various convolution filters on the noise level was evaluated. The change in noise texture introduced by the filtering process was assessed for a limited range of scanner settings by noise analysis of the autocovariance matrix before and after filtering. The results indicate that reduction of noise expressed as RMSD by a factor of about 8 is possible with the filters available in the software package of the Ohio-Nuclear Delta 50 FS tomograph, with some sacrifice in spatial resolution. Results of preliminary experiments with an inhomogeneous phantom are in agreement with this finding and indicate that filtering allows smaller lesions to be detected.

Age at first birth, parity and risk of breast cancer in a Swedish population

A case-control study was conducted over a period of 11 months in an area containing one-third of the Swedish population. One thousand and one patients participated, constituting 94% of all women newly diagnosed as having breast cancer within the area. They were compared with 1,001 age-matched, non-hospitalized controls without breast cancer, selected by paired sampling from a population register. The risk of breast cancer was slightly, but significantly, related to parity, the standardized relative risk (SRR) being 1.35 for nulliparous women as compared to ever parous. In the different parity groups a risk significantly lower than that for nulliparous women was found only for women with more than 2 children (SRR = 0.59) but the trend with parity was highly significant (P less than 0.001). Age at first birth was not found to be an important risk factor for breast cancer. SRR was lower than for nulliparous women in all groups of women with their first birth before the age of 35 years, but the difference was significant (P less than 0.05) only for those with the first birth between 20 and 24 (SSR = 0.69) and 25 and 29 (SRR = 0.69) years of age. The trend with age at first birth (P less than 0.05) disappeared after stratification for parity, suggesting that it was a confounding factor.

Scintigraphic assessment of biliary reflux into the residual stomach after subtotal gastrectomy and gastrojejunostomy

A method is described for evaluating biliary reflux into the gastric remnant after subtotal gastrectomy, avoiding naso- or orogastric intubation. Gamma camera detection and continuous recording of the distribution and possible gastric reflux of 99Tcm-HIDA after intravenous injection was employed, before and after stimulation of bile flow by a fatty meal. The technique is simple and specific, but further clinical evaluation is needed.

Cytoplasmic effects of X-irradiation on cultured cells in a non-dividing stage. 4. Studies of sparsely grown, serum-deprived cells

Cultured human glial cells were blocked in interphase (G1) by 24 h of serum starvation and subsequently subjected to 200 Gy, 8 MV X-radiation. Immediately following irradiation the cultures were transferred to serum-containig medium. Time-lapse cinemicrography performed during the next 48 h showed a profoundly disturbed motility with decreased ability for polarization and locomotion of the irradiated cells. Specimens fixed 24 and 48 h after irradiation and investigated by immunofluorescence with tubulin-antibodies and DNase/DNase-antibodies, and by whole cell transmission electron microscopy showed derangements in the distribution of microfilament bundles related to the cytoplasmic ramification of the irradiated cells, but otherwise no detectable alterations in structure or distribution of either microtubules or microfilaments. It is suggested that the alteration in the arrangement of filament bundles is of importance to the impaired locomotion of the irradiated cells.

Familiality in breast cancer: a case-control study in a Sweden population

1330 consecutively diagnosed breast-cancer patients, and an equal number of paired aged-matched controls without breast cancer, were investigated for a familial history of breast cancer. Patients and controls received identical questionnaires. One relative or more with breast cancer was reported by 18.6% of the patients and by 12.3% of the controls, giving a standardized relative risk (SRR) of 1.6 (P < 0.01). One or more first-degree relatives with breast cancer were reported by 11.2% of the patients and by 6.8% of the controls, with an SRR of 1.7 (P < 0.01). For second-degree relatives the SRR was 1.5 (P < 0.05). Of the patients, 3.9% had mothers with breast cancer compared to 2.7% of the controls (SRR = 1.4, N.S.). One or more sisters with breast canceer were reported by 10.1% of the patients and by 5.1% of the controls (SRR = 2.0, P < 0.01). No distinct difference in familiality between the different age groups was found.

Modification of grey scale in computer tomographic images

Optimum perception of minute but relevant attenuation differences in CT images often requires display window settings so narrow that a considerable fraction of the image appears completely black or white and consequently without structure. In order to improve the display characteristics two principles of grey scale modification are presented. In one method the pixel contents are displayed unchanged within a selectable attenuation band but moved towards the limits of the band for pixels that are outside it. In the other the grey scale is arranged to a constant number of pixels per grey scale interval.

Study of small bowel transport pattern in fasted, conscious rats with an intact gastrointestinal tract. A methodological study with bile-excreted 99Tcm-Solco-HIDA

A method is presented for studies of small bowel propulsion in conscious rats with an intact gastrointestinal tract. A bile-excreted test substance, 99Tcm-Solco-HIDA, was infused intravenously for time periods varying between 0.25 and 5 h. Immediately after the infusion, radioactivity was recorded from the excised bowel specimen. The activity distribution along the small bowel was always found to be 'peaky', i.e. the intestinal contents were transported in portions separated by fairly long completely empty regions. In a control experiment with simultaneous intravenous infusion of 99Tc-Solco-HIDA and infusion of a nonabsorbable test substance (125I-PVP) through a permanent duodenal catheter a similar activity distribution was observed. This indicates that the peaky appearance of the activity distribution is not due to a periodicity in the discharge of bile but reflects small bowel propulsive activity.

Image enhancement by digital-analog filtration. II. Tests of filters

The function of a device for frequency filtration of roentgenograms with digital filters has been tested with the use of different filters. The image was altered in the expected way, which means that the device is suitable for investigating the possibilities of different filters to improve the diagnostic ability. The results of the tests indicate that improvement should be achieved by low-pass filtration.

Protective effect of hypoxia against radiation induced fibrosis in the rat gut

The protective effect of hypoxia, induced by degradable microspheres, against the development of fibrosis was investigated after single-dose irradiation of exteriorized rat ileum. Evaluation, based upon microscopy and analysis of hydroxyproline in protected and nonprotected gut segments, demonstrated an evident protective effect at doses of 15 to 25 Gy.

Gastrointestinal motility and absorption of calcium during infusion of somatostatin in the rat

The effect of somatostatin on gastric evacuation, small bowel propulsion and gastrointestinal (GI) absorption of calcium was studied in conscious rats. Nonabsorbable 125I-PVP was deposited in the stomach or in the duodenum and the distribution of the radioactivity along the excised GI specimen was recorded after 15 min. 47Ca in chloride from was administered simultaneously and the amont of radioactivity remaining in the GI speciment at sacrifice could easily be measured. Intravenous infusion of synthetic somatostatin (50 micrograms.kg-1.h-1), which resulted in a manifest although not extreme hypersomatostatinemia had no effect either on gastric evacuation, small bowel propulsion or GI absorption of calcium. The findings do not indicate that somatostatin has a direct effect on GI motility or absorption of calcium.

Image enhancement by digital-analog filtration. I. Technical description of device

A device for general (10 x 10 pixels) image filtration of 24 cm x 30 cm roentgenograms in the image domain (10(6) pixels) is described. It combines analog and digital techniques and records the processed image on film in the same scale as the original. Results from preliminary tests of the equipment are reported and it is concluded that it yields images with increased perceptibility of large-scale objects of low photographic contrast in the presence of disturbing structures of high spatial frequency and comparably high photographic contrast.

Equivalence of quantitative models for tumour response to ionizing radiation in treatment field optimisation procedures

Three cell kinetic models of tumour response to ionising radiation were compared with regard to their prediction of variation in curability when the dose to the tumour varied between 54 and 66 Gy given in 30 fractions. It was found that a simple model emulated the results of the more complex ones when the parameters of the simple model were properly adjusted. A comparison of the simple model and the CRE formula gave a similar result.

Cytoplasmic effects of X-irradiation on cultured cells in a nondividing stage. 3. Alterations in plasma membrane motility

Cultured, density-dependent growth inhibited human glia cells were exposed to X-radiation, generated by an 8-MeV linear accelerator, at a dose of 200 Gy. Phase contrast microscopy, time-lapse cinemicrography and scanning electron microscopy showed the irradiated cells to have increased ruffling activity of plasma membranes and enhanced macropinocytosis with a maximum approximately 24 hours after irradiation. "Atypical" central ruffles arising from the upper cell surface were demonstrated on some irradiated cells. The turnover of plasma membranes was supposed to be increased in the irradiated cells resulting in the formation of the observed branched, thread-like cells. The diminished cell surface area was believed to result from an unbalance between degradation and renewal of the plasma membranes in the irradiated cells.

Mucosal protection during irradiation of exteriorized rat ileum. Effect of hypoxia induced by starch microspheres

Transient hypoxia induced by intra-arterial injection of degradable starch microspheres was used for protection of exteriorized segments of the rat ileum. Microscopic evaluation of the injury to the mucosa gave a dose modification factor of 0.44 +/- 0.04, which corresponds to an oxygen enhancement ratio of 2.30. A similar factor was also found from measurements of the mucosal weight. No significant development of mucosal oedema could be demonstrated, neither in protected nor in non-protected segments.

Radiation response modified by degradable starch microspheres. Experiments on the rat's foot

Skin reaction in the rat's foot was used as an experimental method to evaluate the protective potential of profound temporary hypoxia against roentgen radiation produced by a linear accelerator. Hypoxia was induced by intraarterial injection of degradable starch microspheres. The irradiation dose needed to evoke a certain reaction in the hypoxic feet was 2.0 times the dose giving the same reaction in a control group. The results point towards a new technique of inducing local hypoxia in healthy tissues which need to be protected in an irradiation field.

Comparative measurements of the mucosal blood flow in the human maxillary sinus by plethysmography and by xenon

Two different methods, one plethysmographic and one where the elimination of radioactive inert gas was measured, have been used to calculate the blood flow in the mucosa of the maxillary sinus in living man. A total of 5 persons were investigated and the mean values of the blood flow in the two methods showed a close correlation. Plethysmography is more easily performed and is therefore the preferable method to be used in studies on the physiology of the maxillary sinus.

Abdominal radiation response modified by hypoxia after intra-aortal injection of starch microspheres. Experiments in the rat

Degradable starch microsphers were injected in the aorta of rats above the level of the superior mesenteric artery 5 min before roentgen irradiation of the abdomen. The local hypoxia, induced by the spheres, was found to have an appreciable protective effect. The dose modification factor was estimated as 0.7.

Cytoplasmic effects of X-irradiation on cultured cells 2. Alterations in lysosomes, plasma membrane, Golgi apparatus, and related structures

Topoinhibited human glia cells in vitro were exposed to X-radiation generated by an 8-MeV linear accelerator at a dose of 20,000 rad. Transmission electron microscopy of irradiated cells at intervals varying between 30 min. and 5 days following irradiation revealed alterations mainly in the plasma membrane and the lysosomal vacuome. Increased ruffling of plasma membranes, augmented endocytosis and extensive intracellular autophagy developed within 24 hours after irradiation. The implications of the plasma membrane alterations are discussed, and a tentative model covering possible mechanism involved in the development of autophagic vacuoles is presented. The possibility is entertained that alternative mechanism may be operative during the formation of the autophagic vacuole in irradiated glia cells. The origin of the isolation membrane appears to be (a) preexisting lysosomes; and (b) flattened vacuolar cytoplasmic elements.

[Measurement of transport in mucous membrane in the human nose with Cr-51-labeled resin beads]

The mucociliary transport of the human nasal mucosa was studied by using very small resin beads tagged with 51Cr. Several modifications of previous methods were introduced, e.g. kind of nuclide, particle size, pH, mode of application, measuring technique and reduction of local irradiation. Finally arrangements implying exact measurements of transport not only horizontally but also vertically or obliquely were obtained. No mucociliary transport was demonstrated in five of nine subjects with a common cold 10 days before or one week after the investigation. Xylometazolin as a nasal spray diminished the mucociliary transport significantly. In addition, the effects on mucociliary transport caused by homolateral or contralateral experimental nasal obstruction as well as by tobacco smoking were studied in healthy subjects. Finally, patients with various diseases: pollen allergy in free intervals, chronic rhinitis, septal deviation or perforation, and condition after laryngectomy were also investigated.

Cytoplasmic effects of x-irradiation on cultured cells in a nondividing stage. 1. Establishment of an experimental model

The investigation was initiated with the aim of establishing a suitable experimental model with respect to mode of radiation and radiation dose for elucidating morphologically the sequential development of radiation induced damage of interphase cells (human glia cells in vitro). Adequately defined and reproducible cellular changes were obtained using X-radiation generated by an 8 MeV linear accelerator at a dose of 20,000 rad. The cellular alterations were studied in the light microscope and by scanning and transmission electron microscopy. The most conspicuous changes--first appreciable about 5 hours after irradiation--occurred in the lysosomal vacuome, and the plasma membrane and associated structures.

High-energy protons in the postoperative treatment of malignant glioma

Fractionated irradiation with high-energy protons was given postoperatively to seven patients with malignant glioma. In four cases in which detailed microscopic examinations were performed, radiation induced tumour necrosis was evident but in all four cases viable tumour cells were also observed. No abnormalities that could be attributed to radiation were observed in brain tissue free from tumour. The therapeutic results were comparable to the results achieved by other modern therapies. The results support the view that the RBE of high-energy protons is similar to that for 60Co radiation. It is suggested that a larger radiation dose, delivered by a homogeneous, well-defined proton field could possibly result in an improved therapeutic result without undue risk of injury to normal brain tissue.

Perception of simulated lesions in the lung

The detectability of phi 20 mm, disk-shaped objects on a normal chest film was investigated at viewing distances of 0.3, 1.0 and 3.0 m. Objects with a tapered border were found to be best perceived at longer distances. The photpgraphic density difference between object and background yielding a 50% detection probability was found to increase from 0.025 to 0.060 when the outer gradient zone of the object increased from 0.8 to 4.0 mm.