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Demonstration of actomyosin in mesangial cells of the renal glomerulus.

Antisera to human uterine actomyosin were prepared in rabbits and conjugated with fluorescein (F-AUAM). When F-AUAM was applied to frozen sections of normal human kidney which were then examined by ultraviolet light microscopy, it was observed that vascular smooth muscle, endothelium of arteries, veins, and peritubular capillaries and glomerular mesangial cells were immunofluorescent. Neither glomerular endothelium nor epithelial cells of Bowman's capsule or renal tubules were stained by F-AUAM. The specificity of antisera for actomyosin was confirmed by absorption and blocking studies, examination of a wide variety of tissues and immunodiffusion in agarose gel. It may be inferred from these data that mesangial cells are contractile. Contraction of the mesangium may play a significant role in regulating glomerular blood flow and in the reaction of the glomerulus to injury.

Actomyosin↗

Yellow hyaline membrane disease. Identification of the pigment and bilirubin binding.

The distinguishing feature of yellow hyaline membrane disease (YHM) in the newborn is the presence of nonfading, bright yellow membrane lining the luminal aspects of conventional pink hyaline membranes (HM). Examination of yellow membranes, stained and unstained, under fluorescent microscopy reveals on orange-red fluorescent material heterogeneously dispersed within the membranes. Homogenates of lungs with YHM and HM were extracted with chloroform and tested spectrophotometrically, by thin layer chromatography, and for diazotized sulfanilic acid reactivity. Spectrophotometric profiles of YHM differed from those of HM by a unique absorption shoulder at 454 nm. in the former. This shoulder corresponded to the absorbance of unconjugated bilirubin. This profile could be reproduced by adding purified unconjugated bilirubin to non-YHM lung homogenate prior to extraction. Thin layer chromatography of the extracted YHM material produced two unique spots not found in extracts prepared from normal or HM-diseased lungs. These spots could be duplicated by thin layer chromatography using pure unconjugated bilirubin. The spots also fluoresced orange-red, the same color initially observed in the membranous preparations under fluorescent microscopy. Additional in vitro binding studies suggest that polymyxin, a decapeptide antibiotic used in endotracheal irrigation of newborn infants, binds bilirubin in pH-dependent, small molecular ratios. Although subsequent clinical studies disproved the etiologic significance of this particular drug, the unique properties of the bilirubin present in the YHMD lungs strongly suggest that the bilirubin there is bound by some yet unelucidated mechanism.

Bilirubin↗

[Determination of aerosol deposition in the maxillary sinus].

The penetration of aerosol into the maxillary sinus depends on the function of the maxillary ostium. Exact findings regarding the velocity of the air flow in the maxillary sinus can be gained by anemometry under optical control of the position of the thermistor. The penetration of aerosol (Patent Blue) can be observed even with a partially closed ostium, and deposit can be documented by photographs. The resorptive process on the mucosa - using fluorescent aerosols - can be visualized by direct excision under UV microscopy. Finally, it is pointed out that the aerosol has a therapeutic value in chronic sinusitis maxillaris even with only partial patency of the ostium.

Aerosols↗

[State of the contractile apparatus during the development of a pathological process in the muscles. V. The effect of Zenker's necrosis and of denervation atrophy on F-actin structure].

By means of polarized UV fluorescent microscopy, the state of F-actin was studied in single glycerinized muscle fibers from intact, locally damaged and denervated m. semi-tendinosus of the frog. It was shown that F-actin of denervated muscle fiber lost the ability to reply by increasing tryptophan fluorescence anisotropy during the fiber relaxation and its stretching in the rigor solution by 1--4 per cent compared to the original length. Zenker's necrosis retains this ability only slightly. It is supposed that both the denervation atrophy and Zenker's necrosis change the structure of F-actin.

Actins↗

Opsonic fibronectin is necessary for optimal serum-mediated phagocytosis of Staphylococcus aureus by human neutrophils.

Opsonic fibronectin is known to mediate reticuloendothelial (RE) cell and neutrophil uptake of nonbacterial particulates. In a recent study opsonic fibronectin deficiency following burn preceded the onset of sepsis, leading us to hypothesize a role for this protein in antibacterial defense. To test this hypothesis we compared pooled normal human serum to fibronectin-depleted serum in its ability to opsonize and promote phagocytosis of Staphylococcus aureus by human neutrophil monolayers. Phagocytosis and intracellular killing were evaluated using acridine orange staining and ultraviolet (UV) microscopy. Human serum depleted of opsonic fibronectin by gelatin-sepharose affinity chromatography manifested a marked reduction in its ability to support phagocytosis of S aureus by human neutrophils. Reconstitution of fibronectin-deficient human serum with purified human plasma fibronectin restored its opsonic activity. The direct interaction of fibronectin with the bacteria was shown by mixing and/or incubation of the bacteria with normal serum followed by centrifugation and removal of the bacteria. This resulted in a marked (P less than 0.05) depletion (adsorption) of the fibronectin from the serum. Fibronectin appears not to act independently, but was an important cofactor in the ability for serum to stimulate phagocytosis. Thus, plasma fibronectin may be an important protein essential for maximal opsonic activity of serum. Its depletion following trauma and burn may undermine RE cell and neutrophil defense against infection and bacteremia, thus contributing to organ failure during septic shock.

Fibronectins↗

Possible mechanisms for the inhibitory effect of Ruscus extract on increased microvascular permeability induced by histamine in hamster cheek pouch.

Extract of Ruscus aculeatus is used in treatment of venous insufficiency. In the present study, we used the hamster cheek pouch preparation and investigated in vivo the effects of an alpha 1 and alpha 2 adrenoceptor antagonists, a calcium blocker, Ruscus extract, and their combination on increased microvascular permeability induced by histamine. Experiments were performed on male hamsters; 30 min after completion of the cheek pouch preparation, fluorescein-labeled dextran (molecular weight 150,000) was given intravenously (i.v.). Histamine, applied topically, increased the number of fluorescent vascular leakage sites from postcapillary venules, evidence of an increase in macromolecular permeability, which was quantified by ultraviolet light microscopy as the number of leaky sites in the prepared area. Prazosin (alpha 1-adrenoceptor antagonist), diltiazem (calcium blocker), and Ruscus extract applied topically dose-dependently inhibited the macromolecular permeability-increasing effect of histamine. Rauwolscine (alpha 2-adrenoceptor antagonist), also applied topically, had no effect on histamine-induced permeability increase. Inhibition of the histamine-induced permeability increase evoked by Ruscus extract could be blocked by prazosin and by diltiazem but not by rauwolscine. These results indicate that any variation in the transmembrane flux of calcium impairs formation of microvascular leaky sites by histamine. Our results show that Ruscus extract has a protective effect against the leakage of FITC-dextran in hamster cheek pouch after administration of histamine that is modulated by calcium and selectively by alpha 1-adrenoceptors.

Animals↗