A Drop-in Gamma Probe for Minimally Invasive Sentinel Lymph Node Dissection in Prostate Cancer: Preclinical Evaluation and Interim Results From a Multicenter Clinical Trial

PURPOSE

This study evaluated the performance of a drop-in gamma probe for prostate cancer (PCa) sentinel lymph node dissection (SLND) in a pelvic phantom, porcine model, and in PCa patients as part of an ongoing prospective multicenter clinical trial.

METHODS

Two design variants of the drop-in gamma probe (SENSEI; Lightpoint Medical Ltd) were assessed in the pelvic phantom, and the preferred design was evaluated in a porcine model with clinically representative volumes and 99mTc activities. In the clinical trial, radical prostatectomy, SLND, and extended pelvic lymph node dissection were performed the day after 99mTc-nanocolloid injection and imaging. Sentinel lymph nodes (SLNs) were detected with the drop-in probe and a rigid laparoscopic gamma probe (RLGP). An interim analysis was performed after 10 patients were recruited.

RESULTS

The narrow field of view probe design outperformed the wide field of view design in the pelvic phantom (detection rate, 100% vs 50%). In the porcine model, all activity concentrations could be successfully detected. The drop-in gamma probe successfully detected SLNs in all 10 patients (detection rate, 100%). Two of the SLNs identified by the drop-in gamma probe could not be found with the RLGP. No false-negative cases and no adverse events related to the SLND procedure or the drop-in gamma probe occurred.

CONCLUSION

The drop-in gamma probe meets the usability and performance requirements for SLND in PCa and provides performance advantages over the RLGP. The final clinical study results will confirm the performance of the technique across multiple sites.

The biochemical mechanisms of the excitotoxicity of kainic acid. Free radical formation

Kainic acid (KA) is a known potent neuroexcitotoxin, although the biochemical mechanism producing its underlying neurotoxic effect is not quite clear. Histopathological examination of gerbil brains 24 h after systemic injection of KA revealed severe neuronal lesions in different regions of the brain, especially the cerebellar and hippocampal areas. We have detected free radical formation in the brain 1 h after KA administration by using an in vivo spin trapping technique. We have also observed increased lipid peroxidation in the brain after KA-treatment by analyzing thiobarbituric acid reactive substances and conjugated diene formation. Diminished brain specific (Na+, K+)-ATPase activity was also found 2 h after KA injection and persisted to 24 h. It is possible that the free radical reaction is a primary cause of neuronal degeneration after KA administration.

Screening for hepatitis B virus markers is not justified in West African transfusion centres

62 severely anaemic Gambian children who were transfused with whole blood not screened for hepatitis B surface antigen (HBsAg) were followed for evidence of hepatitis B virus (HBV) infection over six months. 89% of donors and 44% of recipients before their transfusion had at least one HBV marker. Of the 54 recipient children surviving for the follow-up period, only 1 had a transient rise in liver enzymes. In 13 (37%) of 35 previously uninfected children HBV infection developed within twelve weeks of transfusion. Only 1 of these 13 children followed up at one year had become a persistent HBsAg carrier. The rate at which this cohort acquired persistent HBV infection or clinically important hepatitis was no greater than that in a cohort of similarly aged, nontransfused, children not admitted to hospital. In sub-Saharan Black Africa, where 15% of children have persistent HBV infection by the age of 10 years, HBV screening programmes in transfusion centres cannot at present be justified.

Measles mortality and vaccine efficacy in rural West Africa

Measles mortality and measles vaccine efficacy were determined during outbreaks in three Gambian villages. There were 146 cases of measles among 1073 children younger than 11 years. 30% of the children had been vaccinated against measles. The attack rate in unvaccinated children aged 9-47 months was 43% compared with 6% for children of the same age with documented measles vaccination. Vaccine efficacy was 37% for children vaccinated at 6-8 months of age and 89% for children vaccinated at 9 months or older. 5% of measles cases died before the initial investigation of the outbreaks and a further 10% of cases died during the ensuing 9 months. Only 1% of children who did not contract measles died in the 9 months after the outbreaks. Case-fatality rates were highest for measles patients less than 1 year old (64%) and fell with age. Measles remains a significant source of acute and delayed mortality in unvaccinated African populations.

Environmental Applications of Magnetic Measurements

A wide range of examples of the application of magnetic measurements to environmental studies illustrate the advantages of magnetic techniques over conventional methods. Magnetic measurements, in both the field and the laboratory, are particularly useful for reconnaissance work because of their spee and flexibility, Quantification as well as simple diagnosis of the transformation and movement of magnetic minerals within and between the atmosphere, lithosphere, and hydrosphere is practical. Techniques of investigating intrinsic and mineral magnetic properties, in addition to paleomagnetic remanence, are described in subjects as diverse as meteorology, hydrology, sedimentology, geophysics, and ecology.

Changing Atmospheric Fallout of Magnetic Particles Recorded in Recent Ombrotrophic Peat Sections

Magnetic measurements of ombrotrophic peat allow a reconstruction of changes in the past fallout of magnetic particles through the atmosphere. In recent peat profiles from three sites in Britain and Northern Ireland, a marked increase in saturated isothermal remanent magnetization of the peat is recorded in levels which can be shown to postdate the onset of the Industrial Revolution. Furthermore the spatial variation in contemporary isothermal remanent magnetization values is consistent with a recent industrial and urban origin for the bulk of the magnetic minerals present. Pre-Industrial Revolution values are between two and three orders of magnitude lower, suggesting that the natural cosmic and terrestrial sources previously cited for such material have been dominated in recent times by the products of human activity. Magnetic measurements provide a simple, rapid, and nondestructive method of monitoring and differentiating various types of particulate atmospheric fallout for both recent and preindustrial times.