Construction of a pseudolarynx after laryngectomy and radical neck dissection. A preliminary report

Oxytocin analogues which combine high oxytocic activities with negligible antidiuretic and pressor activities have been studied. [4-Threonine,7-glycine]oxytocin, [1-(L-2-hydroxy-3-mercaptopropionic acid),4-threonine,7-glycine]oxytocin, and [1-(L-2-hydroxy-3-mercaptopropionic acid)]oxytocin were found to possess the following specific biological activities respectively: rat uterotonic, 270 +/- 10, 337 +/- 23, 1542 +/- 0.4; rat antidiuretic, 0.002 +/- 0.0008, 0.048 +/- 0.005, 40.3 +/- 2.4. The results are analyzed from a conformation-activity viewpoint in a continued attempt to evaluate the scope and limitations of this approach in comparison to structure-activity studies.     

Fatty acid metabolism in hypoxic rat liver

Fatty acid metabolism was investigated in adult male albino rats exposed to hypobaric hypoxia at 25,000 ft simulated altitude for 6 h at 32 degrees C. Oxidation and esterification of palmitic acid-1-14C and de novo lipogenesis from acetate-1-14C were studied. Palmitic acid-1-14C oxidation in liver slices was normal while acetoacetate formation was increased. In vivo esterification of palmitic acid-1-14C to form triglycerides was increased while formation of phosphatidylcholine and phosphatidylethanolamine was observed to decrease. Decreased incorporation into plasma phosphatidylcholine with unaltered total activity in plasma triglycerides was observed. The incorporation of acetate-1-14C was observed to remain unaltered in triglycerides and phospholipids of liver with a similar pattern in the plasma indicating unaltered de novo lipogenesis. There appears to be increased esterification of fatty acids with probably impaired release of triglycerides into plasma while fatty acid biosynthesis remains unaffected.     

Massive air embolus to the left ventricle: diagnosis and monitoring by serial echocardiography

Air embolization is an unusual but potentially dangerous complication in left heart catheterization. Microbubbles can be detected with two-dimensional echocardiography, which is often used for this purpose during open heart and bypass surgeries. Permanent neurologic sequelae and hemodynamic collapse can result from embolization of air bubbles to the cerebral and coronary circulations, respectively. Hyperbaric oxygen is the treatment of choice for cerebral air embolization. We present a 39-year-old man who had air embolization during left ventriculography in the form of a large pocket of "pooled" air. The patient was treated with conservative therapy successfully. Two-dimensional transthoracic echocardiography was used to document the presence of the air and follow its dissolution.     

In vivo bone strain patterns in the zygomatic arch of macaques and the significance of these patterns for functional interpretations of craniofacial form

It has been proposed that the mammalian facial skeleton is optimized for countering or dissipating masticatory stress. As optimized load-bearing structures by definition exhibit maximum strength with a minimum amount of material, this hypothesis predicts that during chewing and biting there should be relatively high and near uniform amounts of strain throughout the facial skeleton. If levels of strain in certain areas of the facial skeleton are relatively low during these behaviors, this indicates that the amount of bone mass in these areas could be significantly reduced without resulting in the danger of structural failure due to repeated masticatory loads. Furthermore, and by definition, this indicates that these areas are not optimized for countering masticatory stress, and instead their overall morphology and concentration of bone mass has most likely been selected or influenced mainly by factors unrelated to the dissipation or countering of chewing and biting forces. An analysis of in vivo bone strain along the lateral aspect of the zygomatic arch of macaques indicates the clear absence of a high and near uniform strain environment throughout its extent. Instead, there is a steep strain gradient along the zygomatic arch, with the highest strains along its anterior portion, intermediate strains along its middle portion, and the lowest strains along its posterior portion. These data, in combination with earlier published data (Hylander et al., 1991), indicate that levels of functional strains during chewing and biting are highly variable from one region of the face to the next, and therefore it is unlikely that all facial bones are especially designed so as to minimize bone tissue and maximize strength for countering masticatory loads. Thus, the functional significance of the morphology of certain facial bones need not necessarily bear any important or special relationship to routine and habitual cyclical mechanical loads associated with chewing or biting. Furthermore, the presence of these steep strain gradients within the facial skeleton suggests that the amount of bone mass in the low-strain areas may be largely determined by factors unrelated to processes frequently referred to as "functional adaptation," or conversely, that the "optimal strain environment" of bone varies enormously throughout the facial skeleton (cf., Rubin et al., 1994). Based solely on anatomical considerations, it is likely that the zygomatic arch is bent in both the parasagittal and transverse planes and twisted about its long axis. Due to constraints on rosette position, the strain data are incapable of determining if one or more of these loading conditions predominate. Instead, the strain data simply provide limited support for the possible presence of all of these loading regimes. Finally, as the masseter muscle is concentrated along the anterior portion of the zygomatic arch and as the arch has fixed ends, the largest shearing forces and the largest bending and twisting moments are located along its anterior portion. This in turn explains why the largest strains are found along the anterior portion of the zygomatic arch.     

Organized cell swimming motions in Bacillus subtilis colonies: patterns of short-lived whirls and jets

The swimming motions of cells within Bacillus subtilis colonies, as well as the associated fluid flows, were analyzed from video films produced during colony growth and expansion on wet agar surfaces. Individual cells in very wet dense populations moved at rates between 76 and 116 microm/s. Swimming cells were organized into patterns of whirls, each approximately 1,000 microm2, and jets of about 95 by 12 microm. Whirls and jets were short-lived, lasting only about 0.25 s. Patterns within given areas constantly repeated with a periodicity of approximately 1 s. Whirls of a given direction became disorganized and then re-formed, usually into whirls moving in the opposite direction. Pattern elements were also organized with respect to one another in the colony. Neighboring whirls usually turned in opposite directions. This correlation decreased as a function of distance between whirls. Fluid flows associated with whirls and jets were measured by observing the movement of marker latex spheres added to colonies. The average velocity of markers traveling in whirls was 19 microm/s, whereas those traveling in jets moved at 27 microm/s. The paths followed by markers were aligned with the direction of cell motion, suggesting that cells create flows moving with them into whirls and along jets. When colonies became dry, swimming motions ceased except in regions close to the periphery and in isolated islands where cells traveled in slow whirls at about 4 microm/s. The addition of water resulted in immediate though transient rapid swimming (> 80 microm/s) in characteristic whirl and jet patterns. The rate of swimming decreased to 13 microm/s within 2 min, however, as the water diffused into the agar. Organized swimming patterns were nevertheless preserved throughout this period. These findings show that cell swimming in colonies is highly organized.     

Identification of PLCgamma-dependent and -independent events during fertilization of sea urchin eggs

At fertilization, sea urchin eggs undergo a series of activation events, including a Ca2+ action potential, Ca2+ release from the endoplasmic reticulum, an increase in intracellular pH, sperm pronuclear formation, MAP kinase dephosphorylation, and DNA synthesis. To examine which of these events might be initiated by activation of phospholipase Cgamma (PLCgamma), which produces the second messengers inositol trisphosphate (IP3) and diacylglycerol, we used recombinant SH2 domains of PLCgamma as specific inhibitors. Sea urchin eggs were co-injected with a GST fusion protein composed of the two tandem SH2 domains of bovine PLCgamma and (1) Ca2+ green dextran to monitor intracellular free Ca2+, (2) BCECF dextran to monitor intracellular pH, (3) Oregon Green dUTP to monitor DNA synthesis, or (4) fluorescein 70-kDa dextran to monitor nuclear envelope formation. Microinjection of the tandem SH2 domains of PLCgamma produced a concentration-dependent inhibition of Ca2+ release and also inhibited cortical granule exocytosis, cytoplasmic alkalinization, MAP kinase dephosphorylation, DNA synthesis, and cleavage after fertilization. However, the Ca2+ action potential, sperm entry, and sperm pronuclear formation were not prevented by injection of the PLCgammaSH2 domain protein. Microinjection of a control protein, the tandem SH2 domains of the phosphatase SHP2, had no effect on Ca2+ release, cortical granule exocytosis, DNA synthesis, or cleavage. Specificity of the inhibitory action of the PLCgammaSH2 domains was further indicated by the finding that microinjection of PLCgammaSH2 domains that had been point mutated at a critical arginine did not inhibit Ca release at fertilization. Additionally, Ca2+ release in response to microinjection of IP3, cholera toxin, cADP ribose, or cGMP was not inhibited by the PLCgammaSH2 fusion protein. These results indicate that PLCgamma plays a key role in several fertilization events in sea urchin eggs, including Ca2+ release and DNA synthesis, but that the action potential, sperm entry, and male pronuclear formation can occur in the absence of PLCgamma activation or Ca2+ increase.     

Surface mass spectrometry of biotinylated self-assembled monolayers

Biotin and biotinylated self-assembled monolayers (SAMs) on gold have been investigated using time-of-flight secondary ion mass spectrometry, direct laser desorption, laser desorption with 193 nm photoionization of ion- and laser-desorbed species, and laser desorption with vacuum ultraviolet (VUV, 118 nm) photoionization. Our results indicate that direct laser desorption and laser desorption combined with 193 nm multiphoton ionization can detect a chromophoric molecule like biotin that is covalently bound to a SAM. However, secondary ion mass spectra were dominated by fragmentation, and ion desorption/193 nm photoionization detected no species related to biotin. The dominant features of the laser desorption/VUV mass spectra were neat and Au-complexed dimers of intact and fragmented biotinylated SAM molecules. Multiphoton and single-photon ionization of laser-desorbed neutrals from biotinylated SAMs both led to the production of ions useful for chemical analysis of the monolayer. Multiphoton ionization with ultraviolet radiation was experimentally less challenging but required a chromophore for ionization and resulted in significant fragmentation of the adsorbate. Single-photon ionization with VUV radiation was experimentally more challenging but did not require a chromophore and led to less fragmentation. X-ray photoelectron spectra indicated that the biotinylated SAM formed a disordered, 40-60 ? thick monolayer on Au. Additionally, projection photolithography with a Schwarzschild microscope was used to pattern the biotinylated SAM surface and laser desorption/photoionization was used to detect biotinylated adsorbates from the ～10 μm sized pattern.