The perfused human bronchiolar tube characteristics of a new model.

Strips or rings of airway tissue are often used to study contractile responses of human airways in vitro. These preparations have the disadvantage that it is impossible to deliver stimuli selectively to the mucosal or serosal surface. Hence, they allow only for a limited evaluation of the modulatory role of the airway epithelium. We developed an in vitro model that allows independent stimulation from either the serosal or the mucosal side of human peripheral airways. Segments of human peripheral airways were perfused with a Krebs solution at a constant pressure, and responsiveness was measured as a change in flow rate. Pressure/flow relationships indicated laminar flow over a wide pressure range, and a working pressure of 6 cm H2O was chosen because this is a physiological transpulmonary pressure. When stepwise stretching the airway to 180% of its length, we noted an increase in baseline flow and a decrease in flow reduction after methacholine 10(-5) M. At 140% of the length, accurate and reproducible measurements of the sensitivity (EC50) to methacholine were obtained, and airway closure did not occur. A one-way analysis of variance (ANOVA) revealed that the between-patients differences accounted for 91% of the total variability for -log EC50. We conclude that this in vitro model offers interesting possibilities for evaluating the modulatory effects of the human airway epithelium. In addition, the model provides the opportunity to study human small-airway mechanical properties and secretory functions.     

Atriopeptins and nitroprusside provoke opposite changes in cGMP and cAMP levels in human macrophages.

Atrial natriuretic factor (ANF, 10(-7) M) and, even more potently, sodium nitroprusside (SNP, 10(-5)-10(-3) M) stimulated cGMP formation in human peritoneal macrophages. This suggests that the two forms of guanylate cyclase, the particulate form stimulated by ANF and the soluble form activated by SNP, coexist in this cell type. A fall in cAMP levels in parallel with the rise of cGMP levels provoked by ANF and SNP was noticed that was amplified by an increase in the concentration of the phosphodiesterase inhibitor, IBMX. Our finding that ANF, contrary to its action in other tissues, was unable to exert direct inhibitory effects on the adenylate cyclase activity in isolated macrophage membranes, together with the observation that SNP was able to mimic the effect of ANF on cAMP levels indicates that the cAMP-lowering effect of ANF is most likely mediated through the cGMP signal.     

Computerized analysis of mammographic parenchymal patterns for assessing breast cancer risk: effect of ROI size and location

The long-term goal of our research is to develop computerized radiographic markers for assessing breast density and parenchymal patterns that may be used together with clinical measures for determining the risk of breast cancer and assessing the response to preventive treatment. In our earlier studies, we found that women at high risk tended to have dense breasts with mammographic patterns that were coarse and low in contrast. With our method, computerized texture analysis is performed on a region of interest (ROI) within the mammographic image. In our current study, we investigate the effect of ROI size and ROI location on the computerized texture features obtained from 90 subjects (30 BRCA1/BRCA2 gene-mutation carriers and 60 age-matched women deemed to be at low risk for breast cancer). Mammograms were digitized at 0.1 mm pixel size and various ROI sizes were extracted from different breast regions in the craniocaudal (CC) view. Seventeen features, which characterize the density and texture of the parenchymal patterns, were extracted from the ROIs on these digitized mammograms. Stepwise feature selection and linear discriminant analysis were applied to identify features that differentiate between the low-risk women and the BRCA1/BRCA2 gene-mutation carriers. ROC analysis was used to assess the performance of the features in the task of distinguishing between these two groups. Our results show that there was a statistically significant decrease in the performance of the computerized texture features, as the ROI location was varied from the central region behind the nipple. However, we failed to show a statistically significant decrease in the performance of the computerized texture features with decreasing ROI size for the range studied.     

The effects of leukotrienes,thromboxane A2 and phospholipase A2 on human,porcine and guinea pig lung parenchyma

A comparison was made of the contractions, induced by LTD₄, histamine and phospholipase A₂ in parenchymal strips of guinea pig (GPLP), porcine and human lung in a cascade superfusion system. The effects of LTD₄ and phospholipase A₂ on the release of TxA₂ in these tissues and of TxA₂, 5-HT and acetylcholine on the GPLP were also determined.In the GPLP strip, the LTC₄-induced contractions are due for±80% to the release of TxA₂ and for±20% to the direct effect of LTC₄.The guinea pig tissue displayed the highest sentivity towards all substances, except to the contraction induced by histamine, which was most effective in the porcine tissue. Low activities wer found in the human tissue in all tests. The reason for these effects may be a difference in activities or number of cell types which participate in the reactions leading to the contractions.     

GTP-related difference in cyclic AMP production between resident and inflammatory human peritoneal macrophages.

In macrophages cyclic AMP (c-AMP) plays an important role in regulating many activities such as phagocytosis, migration and tumoricidal activity. High intracellular levels of c-AMP are negatively correlated with these activities. In earlier studies we have shown that c-AMP levels in inflammatory human peritoneal macrophages (IM) were markedly lower when compared to levels in resident macrophages (RM). This is in line with the fact that c-AMP down-regulates macrophage activity. To our knowledge no data are available on the mechanism underlying the difference in c-AMP production between RM and IM. In this study the difference in c-AMP production between RM and IM has been investigated on the level of receptor and G-protein-related mechanisms. Macrophage membranes were incubated with different agents i.e. prostaglandin E2 (PGE2), prostacyclin I2 (PGI2), isoprenalin (ISO) and sodium fluoride (SF). Additionally, the capacity of IM and RM to hydrolyse quanosine triphosphate (GTP) was measured. Only in the presence of GTP (10(-4) M) could the c-AMP difference be detected (RM = 51 +/- 4.4 pmol/mg protein/min +/- S.E., n = 22, IM = 32.8 +/- 5.2 pmol/mg protein/min +/- S.E., n = 10, p less than 0.01). After receptor stimulation with PGE2, PGI2 and ISO, c-AMP levels increased to the same extent in both IM and RM with no effect on the GTP-related difference. After SF stimulation, c-AMP levels in RM and IM increased to the same level (RM = 63 +/- 8 pmol/mg protein/min, n = 14, IM = 58 +/- 11 pmol/mg protein/min, n = 13).(ABSTRACT TRUNCATED AT 250 WORDS)     

EEG-synchronizing effect of gamma-hydroxybutyrate and 1-hydroxy-3-amino-pyrrolidone-2 (HA-966) in relation to dopaminergic brain function.

The earlier finding that γ-hydroxybutyrate and HA-966-induced depression of the central nervous system was associated with the increase of dopamine concentration and block of its release, prompted this study of the influence which the monoaminergic system may have upon the electrocorticogram in rats.The synchronization induced by α-methyl-p-tyrosine began earlier than the decrease of the duration of arousal, indicating different sensitivities to the depressive drug action of structures responsible for synchronizing and for arousal.Five $\text{mg}\text{kg}$ HA-966 in diethyldithiocarbamate desynchronized animals increased the amplitude but the duration of arousal was unchanged. p-Chlorophenylalanine treatment of rats did not influence the synchronizing effect of HA-966 (10–20 $\text{mg}\text{kg}$) or the inhibitory effect upon the duration of arousal. Haloperidol (100 μg-4 $\text{mg}\text{kg}$) potentiated the synchronizing effect of y-hydroxybutyrate and HA-966. The number of phasic discharges in the electrocorticogram induced by treatment with anaesthetic doses of γ-hydroxybutyrate were increased by the low dose of haloperidol (100 $\text{μg}\text{kg}$), while the higher dose (4 $\text{mg}\text{kg}$) was ineffective.Animals with intact and lesioned substantia nigra compacta responded equally to the synchronizing activity of HA-966 and γ-hydroxybutyrate. Therefore, it is concluded that their effect is not due to the accumulation of dopamine in the nigrostriatal system.     

Prostaglandins and ocular inflammation

Evidence for prostaglandins as mediators of some inflammatory responses is briefly, but critically discussed. The hypothesis that prostaglandins are mediators of ocular inflammation is presented and discussed according to the tenets of Miller & Melmon (1970). Prostaglandins are released after mechanical stimulation, paracentesis, laser irradiation, (non)-immunogenic uveitis in experimental animals, and in patients with acute anterior uveitis. Prostaglandins were neither found after antidromic stimulation of the trigeminal nerve, oculomotor nerve stimulation, intracameral formaldehyde, topical nitrogen mustard, nor in patients with open angle glaucoma.Administering of prostaglandins produces transient ocular hypertension, increased vascular permeability and miosis. Ocular hypotension has been shown to follow the hypertensive response. Hypertension is considered to be due to a breakdown of the blood-aqueous barrier of the ciliary processes and iris. Prostaglandins of the E series are the most potent, and species differences occur. Prostaglandin E₁ potentiates the histamine-induced increase in vascular permeability of the conjunctiva, but not the uvea. Polyphloretin phosphate aspecifically blocks the ocular actions of prostaglandins. Non-steroidal anti-inflammatory drugs inhibit prostaglandin synthetase and the ocular effects of arachidonic acid, its substrate. Prostaglandins are poorly catabolised by the eye, but are removed from ocular fluids by a transport mechanism in the anterior uvea. This becomes inoperative in (non)-immunogenic uveitis in rabbits allowing prostaglandins to accumulate. Anti-inflammatory steroids decrease the availability of arachidonic acid for prostaglandin synthetase. Intermediates formed in the biosynthesis of prostaglandins may well be more important in inflammation than the prostaglandins themselves.Part of this review was presented at the 171st Congress of the Dutch Ophthalmological Society.     

Actinomyces-like organisms in users of intrauterine contraception

Actinomyces-like organisms (ALO) were found in 6.9% of cervical smears in 2133 IUD users. The chance of having co-infection with Trichomonas vaginalis was 2.7 times higher in women with ALO than in ALO negative women. The proportion of IUD users with ALO in cervical smears increased with the duration of the IUD use. A total of 108 IUD users with ALO were compared with the same number of IUD users without ALO in cervical smears. The women in the two groups were matched for the duration of the IUD use. During the IUD use the women with ALO had PID and vaginitis significantly more frequently than ALO negative women. No difference was found regarding the type of the IUD used in women with ALO in cervical smears compared to controls.