J. I. Hwang

Exclusive measurement of the nonmesonic weak decay of the lambda(5)He hypernucleus.

We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay of lambda(5)He formed via the 6Li(pi+, K+) reaction. The energies of the two nucleons and the pair number distributions in the opening angle between them were measured. In both np and nn pairs, we observed a clean back-to-back correlation coming from the two-body weak reactions of lambda p --> np and lambda n --> nn, respectively. The ratio of the nucleon pair numbers was N(nn)/N(np) = 0.45 +/- 0.11(stat) +/- 0.03(syst) in the kinematic region of cos theta(NN) < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of gamma(lambda p --> np)/gamma(lambda n --> nn). The ratio is consistent with recent theoretical calculations based on the heavy meson and/or direct-quark exchange picture.We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay (NMWD) of ^{5}_{\Lambda}He formed via the ^{6}Li(\pi^+,K^+) reaction. The energies of two nucleons and the pair number distributions in the opening angle between them were measured. In both np and nn pairs, we observed a clean back-to-back correlation coming from the two-body decay of \Lambda p -->n p and \Lambda n -->n n, respectively. The ratio of the nucleon pair numbers was N_{nn}/N_{np}=0.45 \pm 0.11(stat)\pm 0.03(syst) in the kinematic region of cos(theta_{NN})<-0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of \Gamma(\Lambda p -->np)/\Gamma(\Lambda n -->nn). The ratio is consistent with recent theoretical calculations based on the heavy meson/direct quark exchange picture.

Pilot study on photodynamic therapy for acne using chlorophyll: Evaluator-blinded, split-face study

Since its ability of producing radical oxygen species was known, chlorophyll’s usefulness in photodynamic therapy (PDT) for acne has received great attention (1,2). However, the effect of chlorophyll-PDT for acne has not been reported in the literature so far. We investigated the efficacy and safety of PDT with chlorophyll in four patients (one female, three males) with mild to moderate acne. Exclusion criteria included: (i) age under 18 years; (ii) cystic acne; (iii) photosensitivity; (iv) recent use of photosensitizing agents; (v) use of oral acne treatments within 4 weeks or topical acne treatments within 2 weeks, use of isotretinoin within 6 months; and (vi) pregnancy or lactation. After vigorous scrubbing with acetone and comedone extraction, a 19% a,b-chlorophyll solution (Delta-blue ; Korea Rub, Korea) was applied randomly onto the right or left side of the face. Thereafter, the ipsilateral face was under occlusion for 30–60 minutes and one pass of intense-pulsed light (Ellipse-Flex ; DDD, Denmark), 6–8 J/cm fluence, double-pulse mode, 2.5 ms pulse duration, 10 ms delayed time, was performed on the whole face using a cut-off filter of 530–750 nm (the setting for photorejuvenation). After treatment, sun protection was not required. Three sessions of treatment were repeated at 1-week intervals. At each visit and after a 1-month follow-up, clinical findings (including lesion count, global severity score, subjective self-assessment, photography) were assessed. The degree of improvement was measured as 0–25%, 25–50%, 50–75%, and 75–100% (poor, fair, good, and excellent, respectively). All subjects showed mild improvement after three sessions of PDT. There was a significant reduction in the lesional count at the 1-month follow-up without a significant difference between both sides (Figure 1). With regard to the global severity score, two patients were downgraded as mild to almost clear and the other two patients remained without a change in grade. Subjective self-assessment revealed that the general acne condition and pore size were ‘fair’ or ‘good’ on both sides of the face. However, all patients felt a definite decrease in sebum production on the chlorophyll-treated side to a degree of ‘good’ to ‘excellent’, whereas they felt the improvement in oiliness was ‘poor’ to ‘fair’ on the light-only side. No patient withdrew from the study due to the adverse effects. Chlorophyll has a similar structure with protoporphyrinogen IX and acts as a photosensitizer when it binds to magnesium (3). The absorption spectrums of chlorophyll range from 400 to 700 nm, and show two peak absorbance levels at 415 nm and 630–664 nm (4). Chlorophyll has some advantages compared to aminolevulinic acid (ALA) or methyl aminolevulinic acid (MAL). First, chlorophyll loses its photosensitizing activity within a few hours. Thus, it does not cause a phototoxic reaction when the treated lesion is exposed to the sun. Second, chlorophyll-PDT only requires a relatively short incubation time in comparison with ALA or MAL because this molecule has the characteristics of a photosensitizer itself. Third, cost-effectiveness

New proposal for the treatment of viral warts with intralesional injection of 5-aminolevulinic acid photodynamic therapy

Abstract Background: Although photodynamic therapy (PDT) using intralesional injection (ILI) can theoretically enhance the efficacy of the PDT, the effect of ILI-PDT on warts has not been reported in the literature so far. Methods: Eight patients with multiple viral warts were enrolled in the study. PDT was performed after the incubation for 1 h, followed by the ILI of aminolevulinic acid (ALA) into the warts. The treatment was repeated at 2–3 week intervals. Results: Fifty percent of patients showed good to cure response. Complete remission was observed in two patients. There was no apparent correlation between the initial severity of warts and the likelihood of response. No one reported severe adverse reaction. Conclusions: The present study suggests that intralesional administration of ALA might be a safe and effective treatment option of thick treatment-resistant warts and can be performed with a shorter incubation period.

Postinflammatory melanonychia due to chilblain

Melanonychia is a condition due to the presence of melanin in the nail plate. The clinical types include longitudinal melanonychia (the most common form) and transverse and total melanonychia (relatively rare). Melanonychia develops in conditions with melanocyte activation or hyperplasia. Specifically, multiple bands of melanonychia are usually due to melanocyte activation. We present a case of multiple longitudinal melanonychia caused by postinflammatory hyperpigmentation after chilblain. A 37-year-old man presented with multiple longitudinal brown to black bands on the nails that had developed four years previously. The pigmented bands involved all 20 nails, with hyperpigmentation in the periungual areas of the fingers and toes (Fig. 1). Mucosal and perioral involvement was not observed. The patient immigrated to South Korea 10 years previously from the warmer climate of Indonesia. The patient had chilblain on all of the fingers and toes during the cold seasons. There was no history of trauma, medication, or endocrine disorders. Histologically, the melanin pigmentation was present on all layers of the nail plate (Fig. 2). Melanonychia caused by melanocyte activation often involves several nails and appears more commonly in darker-skinned individuals. Among African-American patients, ‘‘racial’’ melanonychia affects up to 77% of young adults and almost 100% of those older than 50 years. In most cases of racial melanonychia, the involved nails have light brown color pigmentation with no full-width effects. In the current case, the possibility of racial melanonychia was excluded. Pregnancy, inflammatory nail disorders, certain medications, and systemic disorders may cause pigmentary nail changes. A variety of inflammatory skin diseases has been known to activate the nail matrix melanocytes. Psoriasis, Hallopeau’s acrodermatitis, lichen planus, and chronic paronychia have been reported as possible causes of postinflammatory melanonychia. To date, chilblain has not been reported as a cause of postinflammatory melanonychia. Chilblain presents as cutaneous inflammatory lesions commonly involving the fingers, toes, nose, or ears during cold and humid weather. Repeated and prolonged chilblain appeared to cause hyperpigmentation of the effected skin and nails in this patient. Postinflammatory melanonychia can be caused by an increased synthesis of melanin with a normal number of melanocytes. The increased melanin pigment is deposited to the nail plate and forms pigmented bands extending longitudinally from the proximal nail fold (or the lunula) to the free edge of the nail plate. According to Perrin et al., melanocytes in a normal nail matrix may be located at the basal and suprabasal layers. The proximal nail matrix contains a Figure 1 Multiple variable width longitudinal hyperpigmented bands are seen on all toe nails with periungual hyperpigmentation

Coincidence measurement of the nonmesonic weak decay of hyper C-12 (Lambda)

We have measured the angular correlation of the pair nucleons np and nn emitted from the nonmesonic weak decay (NMWD) of ^{12}_{Lambda}C produced via the (pi^+,K^+) reaction in coincidence measurement. The Lambda p -> np and Lambda n -> nn modes were clearly identified by measuring the back-to-back correlation of the emitted nucleon pairs which is the characteristic of two-body kinematics. From the measured nucleon pair numbers N_{nn} and N_{np}, the ratio Gamma_n/Gamma_p of the partial decay widths Gamma_n(Lambda n -> nn) and Gamma_p(Lambda p -> np) of ^{12}_{Lambda}C was extracted to be 0.51+-0.13(stat) +- 0.05(syst); this result is almost free from the ambiguity due to the nuclear final state interaction and 3-body decay process, which were inherent in the previous results. The obtained Gamma_n/Gamma_p ratio of ^{12}_{Lambda}C (p-shell) is close to that of ^5_{Lambda}He (s-shell). The results are consistent with those of recent theoretical calculations.

Neutron and proton energy spectra from the non-mesonic weak decays of 5_Lambda-He and 12_Lambda-C

We have simultaneously measured the energy spectra of neutrons and protons emitted in the non-mesonic weak decays of 5_Lambda-He and 12_Lambda-C hypernuclei produced via the (pi^+,k^+) reaction with much higher statistics over those of previous experiments. The neutron-to-proton yield ratios for both hypernuclei at a high energy threshold (60 MeV) were approximately equal to two, which suggests that the ratio of the neutron- and proton-induced decay channels, Gn(Lambda n ->nn)/Gp(Lambda p ->np), is about 0.5. In the neutron energy spectra, we found that the yield of the low-energy component is unexpectedly large, even for 5_Lambda-He.

Exclusive Measurement of the Nonmesonic Weak Decay of theHeΛ5Hypernucleus

We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay of lambda(5)He formed via the 6Li(pi+, K+) reaction. The energies of the two nucleons and the pair number distributions in the opening angle between them were measured. In both np and nn pairs, we observed a clean back-to-back correlation coming from the two-body weak reactions of lambda p --> np and lambda n --> nn, respectively. The ratio of the nucleon pair numbers was N(nn)/N(np) = 0.45 +/- 0.11(stat) +/- 0.03(syst) in the kinematic region of cos theta(NN) < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of gamma(lambda p --> np)/gamma(lambda n --> nn). The ratio is consistent with recent theoretical calculations based on the heavy meson and/or direct-quark exchange picture.We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay (NMWD) of ^{5}_{\Lambda}He formed via the ^{6}Li(\pi^+,K^+) reaction. The energies of two nucleons and the pair number distributions in the opening angle between them were measured. In both np and nn pairs, we observed a clean back-to-back correlation coming from the two-body decay of \Lambda p -->n p and \Lambda n -->n n, respectively. The ratio of the nucleon pair numbers was N_{nn}/N_{np}=0.45 \pm 0.11(stat)\pm 0.03(syst) in the kinematic region of cos(theta_{NN})<-0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of \Gamma(\Lambda p -->np)/\Gamma(\Lambda n -->nn). The ratio is consistent with recent theoretical calculations based on the heavy meson/direct quark exchange picture.