Improved urethral fluorescence during low rectal surgery: a new dye and a new method.

BACKGROUND: The aim of this study was to demonstrate highlighting of the urethra during surgery through the use of two different methods: a new near-infrared fluorophore IRDye800BK, and indocyanine green (ICG) mixed with silicone. METHODS: Male cadavers from the department of anatomy at the University of Oxford were used to visualise the urethra during near-infrared fluorescence excitation. To assess IRDye800BK, a perineal incision was utilised after infiltrating the urethra directly with an IRDye800BK solution mixed with Instillagel. ICG-silicone was assessed when the urethra was purposely exposed as part of a simulated transanal total mesorectal dissection. ICG was previously mixed with ethanol and silicone and left to set in a Foley catheter. Fluorescence was visualised using an in-house manufactured fluorescence-enabled laparoscopic system. RESULTS: IRDye800BK demonstrated excellent penetration and visualisation of the urethra under fluorescence at an estimated tissue depth of 2 cm. An ICG-silicone catheter demonstrated excellent fluorescence without leaving any residual solution behind in the urethra after its removal. CONCLUSIONS: The newly described ICG-silicone method opens up the possibility of new technologies in this area of fluorescence guided surgery. IRDye800BK is a promising alternative to ICG in visualising the urethra using fluorescence imaging. Its greater depth of penetration may allow earlier detection of the urethra during surgery and prevent wrong plane surgery sooner.

Fluorescence to highlight the urethra: a human cadaveric study.

BACKGROUND: Urethral injury is a complication feared by surgeons performing transanal TME (TaTME) or abdominoperineal excision (APE) procedures. Injury during TaTME occurs when the prostate is inadvertently mobilised or as a direct injury similar to the direct injury during the perineal dissection of APE procedures. We performed a proof of principle study to assess the feasibility of using indocyanine green (ICG) to fluoresce the urethra in human cadavers. METHODS: Indocyanine green at varying doses was mixed with Instillagel and infiltrated into the urethra of male human cadavers. The urethra was exposed through either a perineal incision or by mobilisation of the prostate during a TaTME dissection and fluorescence observed using a PINPOINT laparoscope (NOVADAQ). Brightness was assessed on the images using ImageJ (National Institute of Health). RESULTS: Eight cadavers were included in the study. Fluorescence was visualised in the urethra in all eight cadavers. Minimal dissection was required to obtain fluorescence transperineally. In one cadaver, the urethra was demonstrated under fluorescence using a simulated TaTME with additional fluorescence also being observed in the prostate. There was no correlation between brightness and dosing. CONCLUSIONS: This novel proof of principle study demonstrates a simple way in which the urethra may be easily identified preventing it from injury during surgery.

Asteroseismology. Echography of young stars reveals their evolution.

We demonstrate that a seismic analysis of stars in their earliest evolutionary phases is a powerful method with which to identify young stars and distinguish their evolutionary states. The early star that is born from the gravitational collapse of a molecular cloud reaches at some point sufficient temperature, mass, and luminosity to be detected. Accretion stops, and the pre-main sequence star that emerges is nearly fully convective and chemically homogeneous. It will continue to contract gravitationally until the density and temperature in the core are high enough to start nuclear burning of hydrogen. We show that there is a relationship for a sample of young stars between detected pulsation properties and their evolutionary status, illustrating the potential of asteroseismology for the early evolutionary phases.

Acute AIDS retrovirus infection. Definition of a clinical illness associated with seroconversion.

In the course of a prospective immunoepidemiological study of homosexual men in Sydney, seroconversion to the AIDS-associated retrovirus (ARV) was observed in 12 subjects. Review of the clinical files defined an acute infectious-mononucleosis-like illness in 11 subjects. The illness was of sudden onset, lasted from 3 to 14 days, and was associated with fevers, sweats, malaise, lethargy, anorexia, nausea, myalgia, arthralgia, headaches, sore throat, diarrhoea, generalised lymphadenopathy, a macular erythematous truncal eruption, and thrombocytopenia. In 1 subject an incubation period of 6 days after presumed exposure to ARV was determined and in 3 subjects seroconversion took place 19, 32, and 56 days after onset. Comparison of T-cell subsets before and after the acute illness showed inversion of T4:T8 ratio in 8 subjects, due to increased numbers of circulating T8+ cells. These findings support the notion of an acute clinical, immunological, and serological response to infection with ARV which should be considered in the differential diagnosis of mononucleosis-like syndromes in groups at high risk for the development of AIDS.

Jupiter:observation of deuterated methane in the atmosphere.

A positive identification of singly deuterated methane has been made in the 4- to 5-micron spectrum of Jupiter.