Signal processing in acoustic surface-wave devices

The Rayleigh surface-wave mode propagates on the surface of suitable elastic solids with velocity independent of frequency at about 10-5 times the speed of light and an attenuation of about 1.5 dB for 104 wavelengths. Thus as a delay line it is far more compact, has much less attenuation, and can be much cheaper than electromagnetic delay lines. Piezoelectric elastic solids permit the launching and detection of the waves by electrodes on the surface. Fabrication technology is similar to that used for monolithic semiconductors and amplification is possible by interaction with carriers in a semiconductor surface layer. Parametric interactions can be used to perform convolution of two signals. The feasibility of deflecting and modulating light beams also has been demonstrated. This rapidly developing art can today produce delay lines, filters, pulse compressors and expanders, and pulse-sequence generators and decoders, and in the future may perform convolution, correlation, and light-beam manipulation in small, economical, low-power structures.     

Superior ophthalmic vein at computed tomography

Simultaneous hemodynamic, ventilatory, and blood gas studies were performed in 16 men with congestive heart failure before and during infusion of sodium nitroferricyanide (nitroprusside). The cardiac index increased from 2.00+/-0.16 L/min/sq m (SE) to 2.38+/-0.14 L/min/sq m, and the total pulmonary and systemic peripheral resistances fell from 928+/-123 to 494+/-57 dynes sec cm-5 and from 2,208+/-210 to 1,558+/-121 dynes sec cm-5, respectively. Both systemic and pulmonary arterial decreased during infusion of sodium nitroferricyanide, and the mixed venous oxygen pressure increased. There was no change in total or alveolar ventilation, arterial carbon dioxide tension, pH, or base excess; however, the mean arterial oxygen pressure (PaO2) decreased from 74+/-3 mm Hg to 68+/-3 mm Hg and the venous admixture effect increased from 8+/-1% to 13+/-2%. We conclude that the decrease in PaO2 during infusion of sodium nitroferricyanide resulted from a worsening of the ventilation-perfusion relationships due to increased perfusion of underventilated pulmonary units.     

Comparison of serum myoglobin and creatine kinase MB isoenzyme in early diagnosis of acute myocardial infarction

We compared the clinical usefulness of serum myoglobin and creatine kinase MB (CK MB) isoenzyme determinations in the early diagnosis of acute myocardial infarction in 109 consecutive patients admitted to a coronary care unit. Of these, 37 patients were diagnosed as having definite infarction, three possible infarction, and 69 no infarction, using World Heath Organisation criteria. Blood samples were taken on admission and two to four hours later, Both CK MB and myoglobin were raised in the initial serum samples in 24 of the 37 patients with definite infarction. In an additional seven patients both CK MB and myoglobin were negative in the first specimen though both were detected in the second sample. In five patients CK MB preceded the appearance of myoglobin while in the remaining patient myoglobin appeared before CK MB. We conclude that the detection of serum myoglobin does not offer any clinical advantage over CK MG as an early indicator of myocardial infarction.     

The effects of hyperoxia on the biosynthesis of cyclooxygenase products and haemodynamic response to nitric oxide synthase inhibition with L-NAME in endotoxaemic pigs

The interaction between constitutive nitric oxide and oxygen may depend on the degree of tissue oxygenation and may play a critical role in the pathophysiological response to endotoxaemia. We investigated if hyperoxia (100% O2) attenuated the systemic and pulmonary vasoconstriction and increased biosynthesis of thromboxane B2 (TXB2) and 6-keto-prostaglandin (PG) F1alpha induced by inhibition of nitric oxide synthase with NG-nitro-L-arginine-methyl-ester (L-NAME) in a porcine model of endotoxaemia. Twenty-two domestic, random source pigs, weighing 15.4 +/- 2.7 kg (mean +/- standard deviation) were the subjects of this study. Pigs were anaesthetized with isoflurane in 100% O2, orotracheally intubated and ventilated to maintain normocapnia, and then instrumented for haemodynamic monitoring. Following instrumentation, pigs were maintained at an end-tidal isoflurane concentration of 2%. Pigs were randomly assigned to treatment groups: saline + 30% O2 (Control, n = 6); Escherichia coli lipopolysaccharide (5 microg/kg/h from 1 to 2 h followed by 2 microg/kg/h from 2 to 5 h) + 30% O2 (LPS, n = 4); L-NAME (0.5 mg/kg/h, from 0 to 5 h) + LPS + 100% O2 (n = 6); and L-NAME + LPS + 30% O2 (n = 6). L-NAME and endotoxin significantly (P < 0.05) increased mean arterial pressure, mean pulmonary arterial pressure, and systemic and pulmonary vascular resistance index beginning at 90 min. When results were pooled across all time periods, mean arterial pressure and mean pulmonary arterial pressure were significantly higher in the L-NAME + LPS + 30% O2 group than all other groups, reflecting pulmonary and systemic vasoconstriction. Hyperoxia attenuated the L-NAME + LPS-induced increases in TXB2 and 6-keto-PGF1alpha concentrations at 90 and 120 min and 120 min, respectively, although the differences were not statistically significant. These results support the observation that nitric oxide synthase inhibition with L-NAME has deleterious haemodynamic effects in this model of endotoxaemia. The temporal attenuation of L-NAME-induced pulmonary and systemic vasoconstriction by hyperoxia suggested that the haemodynamic effects of acute endotoxaemia were in part influenced by the relative amounts of nitric oxide and oxygen present.     

Identification of epitope and surface-exposed domains of Shigella flexneri invasion plasmid antigen D (IpaD)

Transport and surface expression of the invasion plasmid antigens (Ipa proteins) is an essential trait in the pathogenicity of Shigella spp. In addition to the type III protein secretion system encoded by the mxi/spa loci on the large virulence plasmid, transport of IpaB and IpaC into the surrounding medium is modulated by IpaD. To characterize the structural topography of IpaD, the Geysen epitope-mapping system was used to identify epitopes recognized by surface-reactive monoclonal and polyclonal antibodies produced against purified recombinant IpaD or synthetic IpaD peptides. Surface-exposed epitopes of IpaD were confined to the first 180 amino acid residues, whereas epitopes in the carboxyl-terminal half were not exposed on the Shigella surface. By using convalescent-phase sera from 10 Shigella flexneri-infected monkeys, numerous epitopes were mapped within a surface-exposed region of IpaD between amino acid residues 14 and 77. Epitopes were also identified in the carboxyl-terminal half of IpaD with a few convalescent-phase sera. Comparison of IpaD epitope sequences with Salmonella SipD sequences indicated that very similar epitopes may exist in the carboxyl-terminal region of each protein whereas the IpaD epitopes in the surface-exposed amino-terminal region were unique for the Shigella protein. Although the IpaD and SipD homologs may play similar roles in transport, the dominant serum antibody response to IpaD is against the unique region of this protein exposed on the surface of the pathogen.     

Validation of a liquid chromatography post-column derivatization assay for the determination of cisplatin in plasma

In previous studies we showed that a single implant of polylactic-co-glycolic acid (PLGA) polymer as a film containing isoniazid ensured sustained release of the drug for up to 4 weeks. These studies have been extended to PLGA polymer as a rod which is retrievable. Both types of implant gave therapeutically active levels of free isoniazid in liver and urine for prolonged periods. We assessed the in vivo chemotherapeutic efficacy of the rod implant against heavy infections of virulent Mycobacterium tuberculosis in C57Bl/6 mice. The chemotherapeutic data essentially confirmed the bioavailability data. In one chemotherapeutic study, one (7%) out of 15 mice which received the isoniazid polymer implant died within 30 days of bacterial challenge, while none of those receiving daily oral treatment died. In contrast, 14 (93%) of the 15 control mice died during the same period. In a second study similar results were obtained.