Evaluation of bone height in osseous free flap mandible reconstruction: an indirect measure of bone mass

Osseous free flaps have become the preferred method of mandibular reconstruction after oncologic surgical ablation. To elucidate the long-term effects of free flap mandibular reconstruction on bone mass, maintenance or reduction in bone height over time was used as an indirect measure of preservation or loss in bone mass. Factors potentially influencing bone mass preservation were evaluated; these included site of reconstruction (central, body, ramus), patient age, length of follow-up, adjuvant radiotherapy, and the delayed placement of osseointegrated dental implants. A retrospective analysis of patients undergoing osseous free flap mandible reconstruction for oncologic surgical defects between 1987 and 1995 was performed. Postoperative Panorex examinations were used to evaluate bone height and bony union after osteotomy. Fixation hardware was used as a reference to eliminate magnification as a possible source of error in measurement. There were 48 patients who qualified for this study by having at least 24 months of follow-up. There were 27 male and 21 female patients, with a mean age of 45 years (range, 5 to 75 years). Mandibular defects were anterior (24) and lateral (24). Osseous donor sites included the fibula (35), radius (6), scapula (4), and ilium (3). There were between zero and four segmental osteotomies per patient (excluding the ends of the graft). Nineteen percent of all patients had delayed placement of osseointegrated dental implants. Initial Panorex examinations were taken between 1 and 9 months postoperatively (mean, 2 months). Follow-up Panorex examinations were taken 24 to 104 months postoperatively (mean, 47 months). The bony union rate after osteotomy was 97 percent. Bone height measurements were compared by site and type of reconstruction. The mean loss in fibula height by site of reconstruction was 2 percent in central segments, 7 percent in body segments, and 5 percent in ramus segments. The mean loss in bone height after radial free flap mandible reconstruction was 33 percent in central segments and 37 percent in body segments; ramus segments did not lose height. The central and body segments reconstructed with scapular free flaps did not lose height, but one ramus segment lost 20 percent of height. There was no loss in bone height in mandibular body reconstruction with the ilium free flap. Fibula free flaps did not significantly lose bone height when evaluated with respect to age, follow-up, radiation therapy, or dental implant placement. The retention in bone height demonstrated in this study suggests that bone mass is preserved after osseous free flap mandible reconstruction. The greatest amount of bone loss was seen after multiply osteotomized radial free flaps were used for central mandibular reconstruction. The ability of the fibula free flap to maintain mass over time, coupled with its known advantages, further supports its use as the "work horse" donor site for mandible reconstruction.     

Interaction of two phenothiazine derivatives with phospholipid monolayers

This paper addresses the cooperative interaction of two phenothiazine drugs, viz. trifluoperazine (TFP) and chlorpromazine (CPZ), with phospholipid monolayers as the model membrane system. Surface pressure and surface potential isotherms were obtained for mixed Langmuir monolayers of either dipalmitoyl-phosphatidyl-choline (DPPC) or dipalmitoyl-phosphatidyl-glycerol (DPPG) co-spread with TFP or CPZ. The changes in monolayer behavior caused by incorporation of a few molar ratio of drug molecules were practically within the experimental dispersion for the zwitterionic DPPC, and therefore a more refined analysis will be required to probe the interactions in an unequivocal way. For the charged DPPG, on the other hand, the surface pressure and the dipole moment were significantly affected even for TFP or CPZ concentrations as low as 0.002 molar ratio. Overall, the effects from CPZ and TFP are similar, but small differences exist which are probably due to the different protonation properties of the two drugs. For both drugs, changes are more prominent at the liftoff of the surface pressure, i.e. at the gas-condensed phase transition, with the surface pressure and surface potential isotherms becoming more expanded with the drug incorporation. With DPPG/CPZ monolayers, in particular, an additional phase transition appears at higher CPZ concentrations, which resembles the effects from increasing the subphase temperature for a pure DPPG monolayer. The dipole moment for DPPG/CPZ and DPPG/TFP monolayers decreases with the drug concentration, which means that the effects from the charged drugs are not associated with changes in the double-layer potential. Otherwise, the effective dipole moment should increase with the drug concentration. The changes caused in surface pressure and dipole moment by small concentrations of TFP or CPZ can only be explained by some cooperative effect through which the contribution from DPPG molecules changes considerably, i.e. even DPPG molecules that are not neighbor to a CPZ or TFP molecule are also affected. Such changes may occur either through a significant reorientation of the DPPG molecules or to a change in their hydration state. We discuss the cooperativity semi-quantitatively by estimating the number of lipid molecules affected by the drug interaction. CPZ and TFP also affect the morphology of DPPG monolayers, which was confirmed with Brewster angle microscopy. The biological implications from the cooperative, non-specific interaction of CPZ and TFP with membranes are also commented upon.     

Redox regulation of RyR-mediated Ca2+ release in muscle and neurons

Changes in the redox state of the intracellular ryanodine receptor/Ca2+ release channels of skeletal and cardiac muscle or brain cortex neurons affect their activity. In particular, agents that oxidize or alkylate free SH residues of the channel protein strongly enhance Ca(2+)-induced Ca2+ release, whereas reducing agents have the opposite effects. We will discuss here how modifications of highly reactive cysteine residues by endogenous redox agents or cellular redox state influence RyR channel activation by Ca2+ and ATP or inhibition by Mg2+. Possible physiological and pathological implications of these results on cellular Ca2+ signaling will be addressed as well.     

Redescription of a rare deep-sea batfish, <Emphasis Type="Italic">Halieutopsis bathyoreos</Emphasis> (Lophiiformes: Ogcocephalidae)

Halieutopsis bathyoreos Bradbury, 1988 (Lophiiformes: Ogcocephalidae), previously described only on the basis of the holotype (62.6mm in standard length) from the central North Pacific, is redescribed on the basis of the holotype and six additional specimens (41.2–68.7mm in standard length) collected from the western South Pacific, off Papua New Guinea, and the western North Pacific, including the Japanese Archipelago. Halieutopsis bathyoreos is distinguished from its congeners by having a shelflike rostrum extending anteriorly well beyond the mouth, a dorsal escal lobe slightly bisected ventrally, an illicial cavity square in outline and completely visible in ventral view, and lacking tubercles on the ventral surface of the disk. The following characters are newly added to the diagnoses of this species: rostrum width 21–29% of head length, tubercles on the dorsal surface of the disk about half the diameter of those on the lateral margin, and 13–15 large lateral-line scales on the tail.     

Triamterene-β-cyclodextrin systems: Preparation,characterization and in vivo evaluation

The purpose of this research was to improve the solubility and therefore dissolution and bioavailability of triamterene, a poorly water soluble diuretic, by complexation with β-cyclodextrin. Triamterene has been reported to show low bioavailability after oral administration, with wide intersubject variation. This study presents the formulation of solid dispersions of triamterene with β-cyclodextrin—by cogrinding, kneading, and coevaporation, using low pH conditions—and their characterizations, evaluation of improvement in dissolution profiles, and in vivo advantage. Phase solubility studies indicated complex with possible stoichiometry of 1∶1 and a stability constant of 167.67M⁻¹. The solid dispersions were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, x-ray diffraction, and differential scanning calorimetry studies. The characterization studies confirmed inclusion of the phenyl ring of triamterene within the nonpolar cavity of β-cyclodextrin in the coevaporate. Remarkable improvement in in vitro drug release profiles in 0.1 N HCl and pH 6.8 phosphate buffer was observed with all dispersions, especially the coevaporate. The coevaporate, when administered orally in rats, also exhibited improved in vivo activity, as measured by net sodium ion excretion, as compared with triamterene powder. Thus, coevaporation of the drug and β-cyclodextrin from acidified alcohol provide the optimum condition for inclusion complexation to give a binary system with remarkable improvement in in vitro drug release profile and in vivo performance.     

Body size and fecundity of Juxtafabia muliniarum (Brachyura: Pinnotheridae) associated with Saccostrea palmula (Bivalvia: Ostreidae), Costa Rica

Size and fecundity observations of pea crab (Juxtafabia muliniarum) from the paleal cavity of the oyster Saccostrea palmula were made from May 1998 to May 1999. Infestation frequency was 18.52% in a sample of 540 oysters. Of 136 pea crabs, 36% were couples, 60% were single females and 4% were single males. The mean caparace length of J. muliniarum was 5.6 +/- 0.74 mm (range 4.0 to 7.6 mm) for females and 2.71 +/- 0.60 mm (range 1.6 to 4.0 mm) for males. The mean weight was 0.180 +/- 0.084 g (range 0.06 to 0.4 g) for females and 0.011 +/- 0.003 g (range 0.01 to 0.02 g) for males. Ovigerous females (43.75% of all females) were found in all months. The caparace length-fecundity relationship was F = 3904.6 Ln (Lc)--4651.1. The caparace length-weight relationship was P = 6 x 10(-4) Lc3.2122. The mean sex-ratio was 1.0 male: 2.4 females. Saccostrea palmula infected only by females was the dominant group (60.78%). This mollusk is a new host record for the crab.