Orthognathic surgery. Restoring form and function of the jaw

Orthognathic surgery can achieve positive changes in a patient's facial appearance and functional abilities. Motivated patients seek this elective treatment, which requires a long-term commitment. By understanding the surgical techniques involved, the perioperative nurse can plan intraoperative care better and help these individuals reach their goals.

Uptake and metabolism of myo-inositol by L1210 leukaemia cells

The initial rate of uptake of [3H]myo-inositol by L1210 murine leukaemia cells is directly proportional to the extracellular concentration and unaffected by several analogues of myo-inositol even at millimolar concentrations. Scyllitol, a geometric isomer of myo-inositol, partially inhibited the uptake of myo-inositol (40% at 0.1 mM). A portion of the uptake of myo-inositol was not inhibited even at 5 mM-scyllitol. At steady-state the intracellular concentration of [3H]myo-inositol is directly proportional to the extracellular concentration. Addition of myo-inositol to medium does not enhance the growth of L1210 cells; these cells can maintain an extracellular concentration of 20 microM-myo-inositol even when grown in myo-inositol-free medium. Synthesis of myo-inositol from glucose by L1210 cells was demonstrated by use of [13C]glucose and m.s. L1210 cells maintain myo-inositol pools by a combination of synthesis de novo and uptake of exogenous myo-inositol by either passive diffusion or a low affinity carrier.

Membrane domains of AChR clusters of cultured rat myotubes revealed by rapid-freeze, deep-etch, rotary-replication

Acetylcholine receptor clusters of cultured rat myotubes are examined by thin-section EM and by rapid-freeze, deep-etch, rotary-replication technique to observe the cortical cytoskeleton; AChR are localized by binding of fluorescent toxin. Cluster membrane is composed of three types of membrane domain which interdigitate with each other. The AChR domain is rich in the integral membrane receptor, lies further from the substrate than the other two, and is overlain by an extensive irregular meshwork of anastomosing filaments containing actin and a beta isoform of spectrin. Contact domains resemble focal contacts of fibroblasts, in that membrane lying close to the substrate is overlain by bundles of actin filaments running parallel to the membrane; some finer filaments link the parallel filaments to each other and to the membrane. Coated-membrane domains are overlain by polymerized clathrin and, like contact domains, lie close to the substrate and have external connections to it; these domains are associated with coated vesicles, but not with intracellular filaments. The three domains have few if any connections to each other, and occupy mutually exclusive territories in the cluster.

Mechanism of DNA strand breaks by mitonafide, an imide derivative of 3-nitro-1,8-naphthalic acid

The metabolism and the mechanism of action of 5-nitro-2-(2-dimethylaminoethyl)-benzo(de) isoquinoline-1,3-dione (mitonafide), a nitro-containing antitumor drug, have been studied. Incubation of mitonafide under anaerobic conditions with rat liver microsomes and NADPH formed the fully reduced amine metabolite, 5-aminomitonafide. The formation of the amine metabolite was not inhibited by SKF-525A, metyrapone or piperonyl butoxide, indicating that the cytochrome P-450 was not involved in this reduction. Incubation of mitonafide with rat liver microsomes and NADPH under aerobic conditions stimulated oxygen consumption; piperonyl butoxide, SKF-525A, superoxide dismutase and catalase had no effect on this stimulation. Both mitonafide and 5-aminomitonafide were found to bind to DNA in a similar manner. However, in inducing single-stand breaks in the DNA of L1210 cells mitonafide was 10-fold more potent than 5-aminomitonafide. These results suggest that metabolic activation of mitonafide to species other than that of the amine metabolite may play a significant role in the induction of DNA damage and the biological activity of the drug.

Regional measurements of [14C]misonidazole distribution and blood flow in subcutaneous RT-9 experimental tumors

Regional [14C]misonidazole-derived radioactivity (MISO*) was measured by quantitative autoradiography in s.c. RT-9 experimental tumors 0.5, 2, and 4 h after an i.v. bolus (25 mg) and constant infusion (10 mg/h) in rats. Misonidazole (MISO) concentration in plasma, tumor, and other tissues was also measured by high-pressure liquid chromatography. The distribution of MISO* in the tumors always resulted in a characteristic pattern with high peripheral and low central values. The high-activity regions in the tumor rim achieved tissue: plasma MISO* activity ratios of 0.97 and 2.2 by 0.5 and 4 h, respectively; for central tumor regions, this ratio was 0.20 and 0.32 for the same periods, respectively. The limited distribution of MISO* to central tumor regions could be correlated to low values of blood flow (measured with [131I]iodoantipyrine) and to diffusion from peripheral tumor regions. Low blood flow in the central regions of these tumors will significantly limit the distribution of MISO and other drugs to viable-appearing cells in these areas and could account in part for the failures of chemotherapy in certain solid tumors. Pharmacokinetic modeling indicates that 1 to 9 h may be necessary for MISO concentrations in some tumor regions to reach 50% of that in plasma.

A third example of haemolytic auto-anti-Vel

A non-transfused, 43 year old Caucasian female presented with acute haemolytic anaemia and splenomegaly. Sections of bone marrow showed erythroid hyperplasia. The patient's red blood cells gave a negative reaction with polyspecific antiglobulin serum, but a positive reaction with specific anti-IgM. A heat eluate prepared from her red cells showed anti-Vel specificity. Her serum agglutinated only Vel-positive cells including her own. All papain pre-treated red cells including her own and Vel-negative cells were completely haemolysed at 37 degrees C. The percentage of haemolysis of Vel-positive cells was greater than that of Vel-negative cells.

Flux through the de novo pyrimidine pathway in vivo. Effect of N-phosphonacetyl-L-aspartate, a potent inhibitor of aspartate transcarbamylase

The activity of the de novo pyrimidine biosynthetic pathway has been measured in resistant and sensitive murine tumors in vivo following a single intraperitoneal dose of N-phosphonacetyl-L-aspartate (PALA) (400 mg/kg). For these studies, we utilized a gas chromatograph-mass spectrometric technique which enabled measurement of 13C incorporation from 13CO2 into the uracil nucleotide pool (sigma uracil) of tumors in situ. Flux through the de novo pathway was 75-85% inhibited 1 h after PALA treatment in both sensitive (Lewis lung carcinoma) and the resistant (L1210) tumors, but there was a lag time before this inhibition was reflected in reduced sigma uracil pools. The activity of the pathway in the Lewis lung carcinoma tumors remained maximally depressed (5-15% of control activity) for up to 48 h after the dose of PALA. In contrast, flux through the pathway of L1210 tumors remained 80% inhibited for up to 4 h following PALA administration, but recovered to 70% of control activity between 4 and 12 h after PALA treatment. Recovery of the remaining 30% of control activity in the L1210 tumor was at a much slower rate requiring between 12 and 48 h after PALA treatment to regain full activity of the pathway. This recovery of flux through the de novo pyrimidine biosynthetic pathway did not correlate with the measurement of recovery of aspartate transcarbamylase activity in similarly treated tumors. These data argue strongly in favor of the importance of the de novo biosynthetic pathway, rather than salvage mechanisms, for determining in vivo sensitivity or resistance of these tumors to PALA treatment.

Regional [14C]misonidazole distribution in experimental RT-9 brain tumors

Regional [14C]misonidazole-derived radioactivity (MISO) was measured by quantitative autoradiography in experimental RT-9 brain tumors 0.5, 2, and 4 hr after an i.v. bolus (25 mg) and constant infusion (10 mg/hr). Misonidazole (MISO) concentration in plasma and brain was also measured by high-pressure liquid chromatography; the brain/plasma MISO ratio ranged between 0.5 and 0.7. MISO equivalents were calculated from tissue or plasma 14C radioactivity and [14C]MISO specific activity data. The MISO/MISO equivalents ratio, which represents the nonmetabolized fraction of [14C]MISO, fell gradually in plasma (0.89 at 4 hr) and more rapidly in brain (0.67 at 4 hr) and tumor (0.30 at 4 hr). MISO distributed uniformly throughout the brain at all three time periods. In contrast, MISO distribution in tumor was variable, and tumor concentrations relative to that in brain increased with time. The average tumor/brain MISO ratio was 1.3, 1.7, and 2.6 at 0.5, 2, and 4 hr, respectively, which suggests tumor uptake and binding of MISO or, more likely, MISO-derived 14C-labeled metabolites. In addition, MISO distribution in tumor tissue was strikingly heterogeneous at 4 hr, resulting in an average high/low tumor activity ratio of 4/1 and an average high tumor/brain ratio of 5/1. Tumor regions with high MISO activity correlated in part to viable-appearing cells around necrotic foci.

Activation of misonidazole by rat liver microsomes and purified NADPH-cytochrome c reductase

Rat liver microsomes and purified NADPH-cytochrome c reductase metabolized [14C]misonidazole anaerobically to a reactive intermediate that covalently binds to tissue macromolecules. Air strongly inhibited the binding whereas carbon monoxide had no effect, indicating that misonidazole is activated via reduction and not by cytochrome P-450-dependent oxidation. Both systems showed an absolute requirement for NADPH and were stimulated by flavine (FAD) and paraquat. The apparent Km for misonidazole binding to microsomal protein was 0.74 mM the apparent Vmax was 0.64 nmole 14C bound . mg-1 . min-1. At a single substrate concentration, nitrofurantoin, nitrofurazone and desmethylmisonidazole inhibited the covalent binding of misonidazole to microsomal protein by 47, 26, and 38% respectively. The effect of nitrofurantoin on the kinetics of misonidazole binding gave a complex interaction indicative of uncompetitive inhibition. Glutathione reduced the binding of misonidazole to microsomal protein below the level observed for boiled microsomes while ascorbic acid had no effect. Compared to nitrofurantoin and paraquat, misonidazole was a poor stimulator of superoxide production as measured by adrenochrome formation.

Infrared emission spectroscopy of glow discharge formed in low pressure atmospheric gases

Laboratory study was conducted on the molecular and atomic emissions which are considered detectable in the IR radiative background of the upper atmosphere. The IR spectra of glow discharge emission formed in air and other atmospheric constituent gases of 0.1-Torr pressure and a 30-m long column were surveyed using the technique of Fourier spectroscopy. Several features hitherto unobserved were detected in our survey study.

Effect of hepatic microsomal enzyme inducers on the metabolism of misonidazole in rats

Pretreatment of rats with the hepatic microsomal enzyme inducers, phenobarbital or phenytoin, increased the metabolism of the hypoxic cell radiosensitizer, misonidazole. The increase was reflected in the ratio of O-demethylated metabolite to unchanged drug in the 24-hour urine collection and was more extensive with phenobarbital. No inducement was observed after pretreatment with dexamethasone or misonidazole. Such pretreatment with inducers prior to misonidazole therapy would be clinically important since the incidence of neurotoxicity may be reduced without impairment of the radiosensitizing effect.

Initiation of light adaptation in barnacle photoreceptors

Intracellular recordings were used to measure the action spectrum of light adaptation in barnacle photoreceptors. The action spectrum closely resembles the absorption spectrum of rhodopsin (lambdamax at 530 nanometers) and is clearly different from that of metarhodopsin (lambdamax at 495 nanometers). These results suggest that absorption of light by rhodopsin initiates both excitation and light adaptation. The previously reported antagonistic process initiated by metarhodopsin does not appear to play a role at moderate light intensities.

Comparison of two radioimmunoassays and a microbiologic assay for bleomycin

Recently two radioimmunoassays have been independently developed for determination of bleomycin levels. In this study these assays are compared with each other and with a standard microbiologic assay for bleomycin. Bleomycin levels were determined in serum and urine samples obtained at varying intervals following intramuscular bleomycin injection. There were systematic differences between the assays. One radioimmunoassay indicated bleomycin levels lower than the levels indicated by the microbiologic assay with serum samples. With urine samples, both radioimmunoassays indicated bleomycin levels greater than the microbiologic assay.

Bleomycin serum pharmacokinetics as determined by a radioimmunoassay and a microbiologic assay in a patient with compromised renal function

Serum and plasma bleomycin concentrations were determined in a patient with renal dysfunction at two creatinine clearances. The results obtained with a new radioimmunoassay and the microbiologic assay were compared. It was shown: 1) that the clearance of bleomycin from the blood is markedly retarded in severe renal dysfunction, 2) that clearance of bleomycin varies with creatinine clearance, 3) that bleomycin is probably not dialyzable, 4) that determinations on serum and plasma were equivalent, and 5) that the radioimmunoassay and microbiologic assays gave equivalent results (P less than 0.001).

Robert williams wood

This short biographical paper supplements, with personal recollections, the record of the life of R. W. Wood, doyen of American physics, as given in DR. WOOD by William Seabrook, and the summary of his work, that appeared in the Journal of the Optical Society of America in 1933 on the occasion of his being awarded the Ives Medal of the Optical Society of America.

Prediction of nighttime driving visibility from laboratory data

The application of laboratory threshold visibility data to the subject of driving visibility with heat absorbing glass has been reviewed in an attempt to resolve excessive differences between calculated predictions and road test observations. New calculations are described that yield predicted losses of visibility distance due to the use of heat absorbing glass rather than regular glass in automobile windshields. The predicted losses agree satisfactorily with the observed losses for road tests, which average proximately 3%. The new calculations have made use of a revised visual exposure interval of ? sec corresponding with five visual fixational pauses per second and a new simulation model that assumes that the target-to-background contrast increases with reduced headlamp-to-target distance.