Laser-tattoo removal--a study of the mechanism and the optimal treatment strategy via computer simulations

BACKGROUND AND OBJECTIVE: The physical mechanisms for laser-tattoo interactions and the tattoo particle breakup process are not well understood. This study investigates whether the mechanism of the breakup process can be identified via computer simulations and proposes a treatment strategy that can potentially minimize the collateral damage to the surrounding tissues. Note that the "removal" of tattoo particles is defined here as breakup of particles into smaller ones with sizes approaching or smaller than the visible wavelength of light so that they become less visible. STUDY DESIGN/MATERIALS AND METHODS: The radiation-hydrodynamics code LATIS is used for the modeling. We first identify the magnitude of the tensile stress generated inside graphite tattoo particles as functions of laser pulse length and particle size. We then calculate the relationship between the surface laser fluence (defined as the time integrated energy flux) and the tensile strength of the tattoo particle at a given depth. RESULTS: If the laser pulse length is sufficiently short, strong acoustic waves with tensile strengths exceeding the fracture thresholds for graphite are generated. The strength of the wave decreases with particle size and increases as the laser pulse length decreases. Simulation results are in general agreement with clinical studies. Although temperatures of the tattoo particles never reach the melting point, a cavitation bubble around the particle can be formed. The steam generated can get into the cracked particles and induce steam-carbon reactions. Laser energy density decreases rapidly with the skin depth. Therefore, the minimum surface laser fluence, for a given pulse length, required for breaking up tattoo particles at a given skin depth, increases with particle depth. CONCLUSIONS: Computer simulations confirm that the breakup of tattoo particles is photoacoustic. For the same amount of laser energy, a shorter pulse is more efficient. The optimal pulse length is approximately 10-100 picosecond to minimize the laser fluence and the collateral damage. It is more difficult to break up the smallest tattoo particles that have diameters smaller than 10 nm; however, smaller particles are less important because they are less visible. Tissue surrounding the tattoo particles can be damaged by cavitation bubbles. These bubbles could be the cause of the empty vacuoles in the ash-white lesions throughout the dermis seen after treatment. Steam-carbon reactions can be induced. Particles then become grossly transparent because of this reaction. Different laser intensity should be used for pigments at different depths in order to minimize the collateral damage to the dermis.     

Using mortuary statistics in the development of an injury surveillance system in Ghana

OBJECTIVE: To develop, in a mortuary setting, a pilot programme for improving the accuracy of records of deaths caused by injury. METHODS: The recording of injury-related deaths was upgraded at the mortuary of the Komfo Anokye Teaching Hospital, Kumasi, Ghana, in 1996 through the creation of a prospectively gathered database. FINDINGS: There was an increase in the number of deaths reported annually as attributable to injury from 72 before 1995 to 633 in 1996-99. Injuries accounted for 8.6% of all deaths recorded in the mortuary and for 12% of deaths in the age range 15-59 years; 80% of deaths caused by injury occurred outside the hospital and thus would not have been indicated in hospital statistics; 88% of injury-related deaths were associated with transport, and 50% of these involved injuries to pedestrians. CONCLUSIONS: Injury was a significant cause of mortality in this urban African setting, especially among adults of working age. The reporting of injury-related deaths in a mortuary was made more complete and accurate by means of simple inexpensive methods. This source of data could make a significant contribution to an injury surveillance system, along with hospital records and police accident reports.     

Insulin-like growth factor I,IGF-binding protein 3, and lung cancer risk in a prospective study of men in China

BACKGROUND: Insulin-like growth factor I (IGF-I) stimulates cell proliferation and inhibits apoptosis in the lung and other tissues by interacting with the IGF-I receptor. The major binding protein for IGF-I, insulin-like growth factor-binding protein 3 (IGFBP-3), modulates the effects of IGF-I but also inhibits cell growth and induces apoptosis independent of IGF-I and its receptor. In a prospective study of men in Shanghai, China, we examined the association between serum levels of IGF-I and IGFBP-3 and the subsequent risk of lung cancer. METHODS: From 1986 to 1989, serum was collected from 18,244 men aged 45-64 years living in Shanghai without a history of cancer. We analyzed IGF-I and IGFBP-3 levels in serum from 230 case patients who developed incident lung cancer during follow-up and from 740 control subjects. RESULTS: Among 230 case patients and 659 matched control subjects, increased IGF-I levels were not associated with increased risk of lung cancer. However, for subjects in the highest quartile relative to the lowest quartile of IGFBP-3, the odds ratio (OR) for lung cancer, adjusted for smoking and IGF-I, was 0.50 (95% confidence interval [CI] = 0.25 to 1.02). When the analysis was restricted to ever smokers (184 case patients and 344 matched control subjects), the OR for lung cancer in men in the highest quartile of IGFBP-3 relative to those in the lowest quartile, adjusted for smoking and IGF-I, was 0.41 (95% CI = 0.18 to 0.92). CONCLUSIONS: In this prospective study of Chinese men, higher serum levels of IGF-I did not increase the risk of lung cancer. However, subjects with higher serum levels of IGFBP-3 were at reduced risk of lung cancer. This finding is consistent with experimental data that indicate that IGFBP-3 can inhibit cellular proliferation and induce apoptosis independent of IGF-I and the IGF-I receptor.     

Gonorrhoea in London: usefulness of first line therapies

OBJECTIVES: To determine the true prevalence and patterns of resistance of Neisseria gonorrhoeae to antimicrobial agents used for therapy in London. METHODS: A longitudinal study of a representative sample of isolates of N gonorrhoeae linked to demographic data of infected patients was undertaken. Isolates were collected from consecutive patients attending genitourinary medicine clinics in the North and South Thames regions of London during 3 months of each of 4 years, 1997-2000. Prevalence of plasmid mediated resistance to penicillin and chromosomally mediated resistance to penicillin and ciprofloxacin was determined by susceptibility testing. The association of antimicrobial resistance among gonococci with sexual orientation of the patient and country of acquisition of infection was determined. RESULTS: Numbers of gonococcal isolates collected over the same time period between 1997-2000 have increased by 74%. Plasmid mediated resistance to penicillin was low but has risen above 5% in 2000. Chromosomal resistance to penicillin has fallen below the 5% level but total resistance to penicillin, plasmid and chromosomally mediated, was above 5% in all 4 years. The incidence of resistance and reduced susceptibility to the alternative therapeutic choice, ciprofloxacin, is low but numbers are increasing in each year. High level resistance, to both penicillin and ciprofloxacin, has generally been found among heterosexual men and is often acquired abroad. However, there is some evidence of a change to endemic spread in 2000. CONCLUSIONS: This surveillance programme shows that the epidemiology of gonorrhoea in London is changing with increasing numbers and changing patterns of resistance. If gonorrhoea is to be controlled and targets set by the sexual health strategy are to be met, intervention with effective and appropriate antimicrobial agents is essential.     

Biliary-enteric transanastomotic stenting with Intestofix

Background: Biliary‐enteric transanastomotic stenting is useful under adverse local conditions or when small‐calibre bile ducts are encountered. Methods: A commercially available feeding jejunostomy kit, Intestofix, was inserted transjejunally through the blind loop of a Roux‐en‐Y hepatico‐jejunostomy. Conclusions: The stent splinted the anastomosis to reduce biliary leaks and may help to prevent subsequent stricture formation.     

sigma(1)-receptor ligand 4-phenyl-1-(4-phenylbutyl)-piperidine affords neuroprotection from focal ischemia with prolonged reperfusion

BACKGROUND AND PURPOSE: We previously showed that the intravenous administration of the potent final sigma(1)-receptor ligand 4-phenyl-1-(4-phenylbutyl)-piperidine (PPBP) provides neuroprotection against transient focal cerebral ischemia and that the protection depends on treatment duration. We tested the hypothesis that PPBP would provide neuroprotection in a model of transient focal ischemia and 7 days of reperfusion in the rat as assessed with neurobehavioral outcome and infarction volume. METHODS: Under the controlled conditions of normoxia, normocarbia, and normothermia, halothane-anesthetized male Wistar rats were subjected to 2 hours of middle cerebral artery occlusion (MCAO) with the intraluminal suture occlusion technique. We used laser Doppler flowmetry to assess MCAO. At 60 minutes after the onset of ischemia, rats were randomly assigned to 1 of 4 treatment groups in a blinded fashion and received a continuous intravenous infusion of control saline or 0.1, 1, or 10 micromol. kg(-1). h(-1) PPBP for 24 hours. Neurobehavioral evaluation was performed at baseline (3 to 4 days before MCAO) and at 3 and 7 days of reperfusion. Infarction volume was assessed with triphenyltetrazolium chloride staining on day 7 of reperfusion in all rats. RESULTS: Triphenyltetrazolium chloride-determined infarction volume of ipsilateral cortex was smaller in rats treated with 10 micromol. kg(-1). h(-1) PPBP (n=15, 68+/-12 mm(3), 18+/-3% of contralateral structure, P<0.05) (mean+/-SEM) compared with corresponding rats treated with saline (n=15, 114+/-11 mm(3), 31+/-3% of contralateral structure). PPBP did not provide significant neuroprotection in the caudoputamen complex. Although MCAO was associated with several alterations in behavior, the treatment with PPBP had no effect on behavioral outcomes. CONCLUSIONS: The data demonstrate that the potent final sigma(1)-receptor ligand PPBP decreases cortical infarction volume without altering neurobehavior after transient focal ischemia and prolonged reperfusion in the rat.     

Increased occupancy of dopamine receptors in human striatum during cue-elicited cocaine craving.

In all, 19 research subjects, with current histories of frequent cocaine use, were exposed to cocaine-related cues to elicit drug craving. We measured the change of occupancy of dopamine at D2-like receptors with positron emission tomography (PET) and inferred a change of intrasynaptic dopamine (endogenous dopamine release), based on the displacement of radiotracer [(11)C]raclopride. Receptor occupancy by dopamine increased significantly in putamen of participants who reported cue-elicited craving compared to those who did not. Further, the intensity of craving was positively correlated with the increase in dopamine receptor occupancy in the putamen. These results provide direct evidence that occupancy of dopamine receptors in human dorsal striatum increased in proportion to subjective craving, presumably because of increased release of intrasynaptic dopamine.