Performance of QUiPP App v.2 tool for prediction of preterm birth in asymptomatic high-risk women attending preterm specialist clinic: external validation study.

OBJECTIVE: To validate externally the QUiPP App v.2 algorithms in an independent cohort of high-risk asymptomatic women attending a preterm birth (PTB) surveillance clinic in Ireland. METHODS: This was a retrospective, single-center, observational study assessing discrimination and calibration of the QUiPP App v.2 at six predetermined clinical timepoints (PTB at < 30, < 34 and < 37 weeks of pregnancy and PTB within 1, 2 and 4 weeks of testing). Discrimination was assessed by estimating the area under the receiver-operating-characteristics curve (AUC) and sensitivity at fixed false-positive rates of 5%, 10% and 20%. Model calibration was assessed to evaluate the concordance between expected and observed outcomes. P-values < 0.05 were considered statistically significant. No adjustments for treatment effects were made. RESULTS: Overall, 762 women with 1660 PTB surveillance clinic visits using the QUiPP App v.2 between 2019 and 2022 were analyzed. The study population included 142 (18.6%) patients who later experienced PTB. The QuiPP App's performance in the prediction of short-term outcomes, such as birth within 1 week (AUC, 0.866 (95% CI, 0.755-0.955)), 2 weeks (AUC, 0.721 (95% CI, 0.569-0.854)) and 4 weeks (AUC, 0.775 (95% CI, 0.699-0.842)), and delivery at < 30 weeks (AUC, 0.747 (95% CI, 0.613-0.865)), was superior to its ability to predict longer-term outcomes (PTB at < 37 weeks: AUC, 0.631 (95% CI, 0.596-0.668)). Calibration was generally good for low-risk results, as the predicted risk in these patients tended to match the observed incidence. However, in women deemed to be at greater risk of PTB, the predicted probability superseded the observed incidence of PTB. CONCLUSIONS: The QUiPP App v.2 accurately discriminates women who are at short-term risk of PTB. A 'treatment paradox' may influence calibration in high-risk women. Further research is needed to ascertain if QuiPP treatment thresholds can be safely adjusted in women receiving prophylactic treatment to prevent PTB, and whether this improves the outcome. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

A re-evaluation of teenage sunbed use following the introduction of banning legislation for under 18-year-olds.

BACKGROUND: There is little information on the effectiveness of introducing age restriction legislation alone to reduce the rate of sunbed usage by teenagers. Prior to the Public Health (Sunbed) Act of 2014 prohibiting the use of sunbeds in under 18-year-olds in Ireland we reported the rate of sunbed use at 7.5%. OBJECTIVES: The aim of the study was to compare the rate of sunbed usage among Irish teenagers before and after the introduction of banning legislation to determine if it had the desired effect of reducing its rate of use. METHODS: In a cross-sectional survey, students from the same schools as in our previous study completed an anonymous, written questionnaire pertaining to sunbed usage. RESULTS: In total, 783 questionnaires, from 13 schools across Ireland, were completed. The rate of sunbed use in the current study was 7.2%, compared to 7.5% in the pre-ban study, (P = 0.76). A higher rate of sunbed use was observed in Dublin schools and female public students. CONCLUSION: Our study suggests that legislation alone is ineffective at reducing sunbed usage in a teenage population. A multifaceted approach is required that includes enforcement of the legislation together with targeted public education and awareness campaigns using all aspects of the media.

Experience of skin disease and relationships with healthcare providers: a qualitative study of Traveller women in Ireland.

BACKGROUND: Significant health disparities exist between members of the Travelling community and those of the general population. Barriers to Traveller engagement with health services include the experience or perception of discrimination, and cultural and health literacy barriers. Experience of skin disease and interactions with healthcare providers has not been widely explored in this ethnic minority. The formation of positive relationships between the Travelling community and healthcare providers is important in the promotion of treatment adherence and improving health outcomes. OBJECTIVES: To investigate Travellers' experience of skin disease and their relationships with healthcare providers. METHODS: Focus groups were conducted with a purposive sample of female members of the Irish Travelling community with experience of skin health issues, between January 2018 and April 2018. Three focus groups were conducted at three separate locations with 10 participants in each group. Themes were identified from the focus group transcripts using an inductive thematic analysis framework. RESULTS: Emergent themes surrounding relationships between Travellers and healthcare providers included health literacy, discrimination, information inconsistency, trust and communication. Factors that were valued in the creation of positive relationships included an appreciation of varying degrees of health literacy, the provision of sufficient information tailored to an individual's needs and a demonstration of cultural competence. CONCLUSIONS: Dermatologists are well placed to provide practical, customized, treatment guidance and engage patients while integrating their culturally based beliefs.

Sonographic markers of fetal adiposity and risk of Cesarean delivery.

OBJECTIVE: Increased fetal size is associated with shoulder dystocia during labor and subsequent need for assisted delivery. We sought to investigate if increased fetal adiposity diagnosed sonographically in late pregnancy is associated with increased risk of operative delivery. METHODS: This secondary analysis of the Genesis Study recruited 2392 nulliparous women with singleton pregnancy in cephalic presentation, in a prospective, multicenter study, to examine prenatal and intrapartum predictors of Cesarean delivery. Participants underwent ultrasound and clinical evaluation between 39 + 0 and 40 + 6 weeks' gestation. Data on fetal biometry were not revealed to patients or to their managing clinicians. A fetal adiposity composite of fetal thigh adiposity and fetal abdominal wall thickness was compiled for each infant in order to determine whether fetal adiposity > 90th centile was associated with an increased risk of Cesarean or operative vaginal delivery. RESULTS: After exclusions, data were available for 2330 patients. Patients with a fetal adiposity composite > 90th centile had a higher maternal body mass index (BMI) (25 ± 5 kg/m2 vs 24 ± 4 kg/m2 ; P = 0.005), birth weight (3872 ± 417 g vs 3585 ± 401 g; P < 0.0001) and rate of induction of labor (47% (108/232) vs 40% (834/2098); P = 0.048) than did those with an adiposity composite ≤ 90th centile. Fetuses with adiposity composite > 90th centile were more likely to require Cesarean delivery than were those with adiposity composite ≤ 90th centile (P < 0.0001). After adjusting for birth weight, maternal BMI and need for induction of labor, fetal adiposity > 90th centile remained a risk factor for Cesarean delivery (P < 0.0001). A fetal adiposity composite > 90th centile was more predictive of the need for unplanned Cesarean delivery than was an estimated fetal weight > 90th centile (odds ratio, 2.20 (95% CI, 1.65-2.94; P < 0.001) vs 1.74 (95% CI, 1.29-2.35; P < 0.001). Having an adiposity composite > 90th centile was not associated with an increased likelihood of operative vaginal delivery when compared with having an adiposity composite ≤ 90th centile (P = 0.37). CONCLUSIONS: Fetuses with increased adipose deposition are more likely to require Cesarean delivery than are those without increased adiposity. Consideration should, therefore, be given to adding fetal thigh adiposity and abdominal wall thickness to fetal sonographic assessment in late pregnancy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Photoreactivity, Optical Behavior and DFT Studies of 2,5-Bis[4-choloro-acetyl(thiophen-2-ylmethylene)]cyclopentanone BCTCP in Different Solvents.

Diarylidenecyclopentanone compound namely, 2,5-bis[4-choloroacetyl-(thiophen-2-ylmethylene)]cyclopentanone (BCTCP) was firstly synthesized using the normal condition of Friedel-Crafts method by reacting 2,5-bis(thiophen-2-ylmethylene)cyclopentanone (BTCP) with chloroacetyl chloride in the presence of aluminum chloride anhydrous. The structure of this compound was confirmed by elemental and spectral analyses including FT-IR, 1H-NMR, 13C-NMR and mass spectrometry. The electronic absorption and emission properties of BCTCP were studied in different solvents. BCTCP displays a slight solvatochromic effect of the absorption and emission spectrum, indicating a small change in dipole moment of BCTCP upon excitation. BCTCP displayed photodecomposition in chlorinated solvents upon irradiating with 365 nm light. Ground and excited states electronic geometric optimizations were performed using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. A DFT natural bond orbital (NBO) analysis complemented the intramolecular charge transfer (ICT). The simulated maximum absorption and emission wavelengths are in line the observed ones in trend, and were proportionally red-shifted with the increase of the solvent polarity. The stability, hardness and electrophilicity of BCTCP in different solvents were correlated with the polarity of the elected solvents.

Multivalent linkers for improved covalent binding of oligonucleotides to dye-doped silica nanoparticles.

This paper describes the fabrication of oligonucleotide-coated Cy5-doped silica nanoparticles using a combination of multivalent linkers and their use in surface-based DNA sandwich hybridization assays. Dipodal silane is introduced as a means to fabricate amine-coated silica nanoparticles and its advantages compared to monopodal silanes are discussed. The use of dipodal silane in conjunction with three different polymer linkers (oxidized dextran, linear and 8-arm polyethylene glycol (PEG)) to immobilize single-stranded DNA to Cy5-doped nanoparticles is investigated and dynamic light scattering measurements and Fourier transform infrared spectroscopy are used to follow the progression of the functionalization of the nanoparticles. We observe a significant improvement in the binding stability of the single-stranded DNA when the dipodal silane and 8-arm PEG are used in combination, when compared to alternative conjugation strategies. Both 8mer and 22mer oligonucleotides are securely conjugated to the high-brightness nanoparticles and their availability to hybridize with a complementary strand is confirmed using solution-based DNA hybridization experiments. In addition, a full surface-based sandwich assay demonstrates the potential these nanoparticles have in the detection of less than 500 femtomolar of a DNA analogue of micro RNA, miR-451.

Prevena™, negative pressure wound therapy applied to closed Pfannenstiel incisions at time of caesarean section in patients deemed at high risk for wound infection.

The aim of our retrospective study is to report on our experience using the Prevena™ wound system in obese patients undergoing caesarean section delivery. A total of 26 cases were identified from July 2012 to October 2013. The median BMI of these women was 45.3 kg/m(2). Elective caesarean sections were performed in 20 women (77%). There were four cases (15%) of superficial dehiscence. Factors associated with wound breakdown were wound infection (p = 0.03), increasing BMI (p < 0.001) and emergency LSCS (p = 0.04). In a logistic regression model the presence of infection was the only factor which remained associated with wound breakdown. Wound disruption is a major cause of morbidity following caesarean section in morbidly obese patients. The wound complication rate in our experience was low with the Prevena™ dressing with no cases of sheath dehiscence, and no patient required a second operation. The presence of infection is the most important factor in wound breakdown and should be the focus for management protocols.

Experimental determination of ground and excited state dipole moments of N, N-bis (2, 5-di-tert-butylphenyl)-3, 4:9, 10-perylenebis (dicarboximide) (DBPI) a photostable laser dye.

In the present work, the absorption, emission spectra and dipole moments(µ(g), µ(e)) of N, N-bis (2, 5-di-tert-butylphenyl)-3, 4:9, 10- perylenebis (dicarboximide) (DBPI) have been studied in solvents of various polarities at room temperature. Using the methods of solvatochromism, the difference between the first excited singlet state (µ(e)) and ground state (µ(g)) dipole moments was estimated from Lippert - Mataga,, Bakhshiev, Kawski - Chamma - Viallet equations. The change in dipole moment (Δµ) was also calculated using the variation of the Stokes shift with microscopic solvent polarity parameter (E(T)(N)). It was observed that the value of excited singlet state dipole moment is higher (3.53 Debye) than the ground state one (1.92Debye), showing that the excited state of DBPI is more polar than the ground state.

Umbilical and fetal middle cerebral artery Doppler reference ranges in a twin population followed longitudinally from 24 to 38 weeks' gestation.

OBJECTIVE: To construct monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin reference ranges for umbilical artery (UA) pulsatility index (PI), UA resistance index (RI), fetal middle cerebral artery (MCA) PI and peak systolic velocity (PSV) and cerebroplacental ratio (CPR) from 24 weeks' to 38 weeks' gestation and compare these with published normal values for singleton pregnancies. METHODS: This prospective multicenter cohort study included 1028 unselected twin pairs recruited over a 2-year period. Participants with dichorionic twins underwent fortnightly ultrasound surveillance from 24 weeks' gestation, with monochorionic twins being followed every 2 weeks from 16 weeks until delivery. A total of 7536 fetal Doppler examinations in 618 twin pregnancies were included in the analysis, with reference ranges for MCDA and DCDA pregnancies constructed for each of the Doppler indices using multilevel modeling. RESULTS: UA-PI and UA-RI appear to be higher in twins than in singletons, and MCA-PI and MCA-PSV appear to be lower. The CPR also appears to be lower in twins than in singletons. Similar MCA indices were observed in MCDA and DCDA twins. CONCLUSION: We have established longitudinal reference ranges for UA-PI and UA-RI, MCA-PI and MCA-PSV and CPR in twin pregnancies, which appear to differ from those in singleton pregnancies. The derived twin-specific reference ranges may be more appropriate in the surveillance of these high-risk pregnancies. Applying the singleton CPR cut-off of ≤ 1.0 may lead to a large number of false-positive diagnoses of cerebral redistribution in twin fetuses.

Repeat patient testing-quality control compared to commercial quality control material for the Sysmex XT-2000iV hematology analyzer in a multi-site veterinary laboratory.

BACKGROUND: Quality control material (QCM) for hematology in veterinary laboratories is limited, and repeat patient testing quality control (RPT-QC) is an alternative method using excess matrix-specific samples. OBJECTIVES: This study aimed to determine if median differences between RPT-QC analyses for each time interval for RBC, HGB, HCT, and WBC were the same, determine if unified RPT-QC limits can be applied to a network of veterinary laboratories, compare the performance of RPT-QC to commercial QCM for the reference analyzer and evaluate the experience over a 4 month period and design, improve and implement an automated spreadsheet for RPT-QC data management. METHODS: The potential to unify individual analyzer RPT-QC limits for red blood cells (RBC), hematocrit (HCT), hemoglobin (HGB), and white blood cells (WBC) on multi-site Sysmex XT-2000-iV analyzers was explored by a difference of means test and confidence interval determination for the median difference for each network analyzer in comparison to the network reference analyzer. User experience of an automated RPT-QC data management Excel spreadsheet was collected by user feedback during monthly meetings. Numbers of out-of-control results and the root causes for these for RPT-QC were compared against those of a commercial QCM over a 4-month period. RESULTS: Differences between individual analyzer RPT-QC limits were too large to allow for unification of network limits. The automated spreadsheet successfully highlighted out-of-control events for RPT-QC. Trends or shifts were more frequent for commercial QCM based on observed performance and a 1-2.5 s QC rule than for RPT-QC. Following routine troubleshooting, RPT-QC out-of-control events were resolved with an alternative RPT-QC sample indicating random error associated with excessive deterioration. Use of an automated spreadsheet for recording RPT-QC, documentation and troubleshooting of out-of-control events, and collating monthly summary calculations were considered an asset in laboratory quality management. CONCLUSIONS: RPT-QC can be successfully implemented and integrated into a multi-site veterinary laboratory. Individual analyzer RPT-QC limit generation is recommended. The deterioration of commercial QCM caused shifts or trends in QC results, which initiated more repeat analyses and investigations than did RPT-QC.

Perinatal and neonatal outcomes of high-risk asymptomatic women from a specialist preterm birth surveillance clinic.

OBJECTIVES: To report the perinatal outcomes of high-risk asymptomatic women who attended a specialist preterm surveillance clinic (PSC) to undergo screening for spontaneous preterm birth (PTB) in Ireland. METHODS: Single center, retrospective cohort study of asymptomatic high risk women who attended the PSC between January 2019 and December 2022. A comprehensive database of all patients who attended the clinic during the study period was constructed and analyzed. Overall outcomes were reported, and stratified per the occurrence of preterm or term birth. Iatrogenic PTBs were included in the outcome data. RESULTS: Following exclusions for loss-to-follow-up, 762 cases were analyzed, constituting 2262 PSC visits. Of those, 183 women were prescribed progesterone (24.0 %), and 100 women underwent cervical cerclage (13.1 %) to prevent spontaneous PTB. Overall, 2.4 %, 6.2 % and 18.6 % of participants gave birth prior to 30 weeks, 34 weeks, and 37 weeks, respectively. The median gestational age at birth for the entire cohort was 38.6 weeks (inter-quartile range (IQR) 37.2-39.6 weeks). Women who delivered < 37 weeks were significantly more likely to be smokers (p = 0.030), have a previous spontaneous PTB (p = 0.016), have multiple pregnancies (p < 0.001), type 1 or 2 diabetes (p = 0.044), or have a previous full dilatation caesarean section birth (p = 0.024). Infants born prior to 37 weeks were more likely to have a lower median birthweight (2270 vs 3300 g, p < 0.001), be admitted to a neonatal intensive care unit (53.8 % vs 2.3 %, p < 0.001) or experience short-term morbidity, including respiratory support (38.0 % vs 1.6 %, p < 0.001). CONCLUSIONS: Over 80% of women deemed to be at high risk of PTB gave birth at term gestations following attendance at a PSC during pregnancy. Most women can be successfully managed without interventions, instead employing a policy of serial cervical surveillance, to identify those at greatest risk of PTB.

Mode of conception of triplets and high order multiple pregnancies.

A retrospective audit was performed of all high order multiple pregnancies (HOMPs) delivered in three maternity hospitals in Dublin between 1999 and 2008. The mode of conception for each pregnancy was established with a view to determining means of reducing their incidence. A total of 101 HOMPs occurred, 93 triplet, 7 quadruplet and 1 quintuplet. Information regarding the mode of conception was available for 78 (81%) pregnancies. Twenty eight (27.7%) were spontaneous, 34 (33.7%) followedlVF/ICSI/FET treatment (in-vitro fertilisation, intracytoplasmic sperm injection, frozen embryo transfer), 16 (15.8%) resulted from Clomiphene Citrate treatment and 6 (6%) followed ovulation induction with gonadotrophins. Triplet and HOMPs are a major cause of maternal, feta land neonatal morbidity. Many are iatrogenic, arising from fertility treatments including Clomiphene. Reducing the numbers of embryos transferred will address IVF/ICSI/FET-related multiple pregnancy rates and this is currently happening in Ireland. Clomiphene and gonadotrophins should only be prescribed when appropriate resources are available to monitor patients adequately.

Grey hair: clinical investigation into changes in hair fibres with loss of pigmentation in a photoprotected population.

Loss of pigmentation in hair fibres is one of the most obvious phenotypic changes with ageing and has been a topic of increasing interest in the study of follicle biology. The onset of greying brings cosmetic complaints that grey fibres are wild or difficult to manage. Of course, these perceptions may be the consequence of visual obviousness rather than underlying physical or chemical differences. Although several studies have compared pigmented and unpigmented fibres, few have tried to control genetic and ethnic difference as well as extrinsic factors such as photoexposure and chemical treatment. We have recruited subjects with salt-and-pepper hair from a population of Old Order Mennonites who, for cultural reasons, are not only prohibited from chemically treating their hair but also limit their exposure to sunlight. Hair samples were examined for elemental composition, surface energy, Young's modulus, break stress, bending modulus, shear modulus and water sorption/desorption isotherm. The parameters were evaluated statistically for global differences, individual differences and typical individual differences. Consistent with previous published literature, few global differences were found between pigmented and unpigmented hair across the population. We do find that many individual subjects had differences between pigmented and unpigmented fibres. These differences tend to be more pronounced in bulk than in surface properties. The small differences in mechanical properties and moisture uptake and loss lend support to the perception by consumers that grey hair is wilder, drier and less manageable.

Direct excitatory interactions between cones of different spectral types in the turtle retina.

Cone linear sensitivities to red and green stimuli were measured intracellularly in the dark- and light-adapted turtle retina. Test flashes of small diameter were used to minimize horizontal cell feedback. Light adaptation was achieved with either green or red background illumination. The ratio of cone sensitivities to red and green light depended on the color of the background light and differed from the ratio measured in the dark. Electron microscope studies of Golgi-stained turtle cones revealed direct synaptic connections between red and green cones mediated by cone telodendria. These data indicate that the red cone photoresponse is not univariant as has been previously supposed and suggest that mixing of signals from different spectral classes of cones can occur via direct excitatory connections between cones.

Occupational predictors of pregnancy outcomes in Irish working women in the Lifeways cohort.

OBJECTIVE: The objective of this study was to explore the association between occupational factors and pregnancy outcomes in a prospective cohort of Irish pregnant women. DESIGN: This study has a prospective design. POPULATION: The Lifeways cohort included 1124 pregnant women, 676 of whom delivered a single baby and were working at their first prenatal care visit when they filled in a self-administered questionnaire. METHODS: Occupational factors were measured using this questionnaire and included eight factors describing job and working conditions. Data including pregnancy outcomes were also obtained from clinical hospital records. Logistic regression analysis was used to adjust for well-known risk factors. MAIN OUTCOME MEASURES: Birthweight (< or =3000 g and < or =2500 g), preterm delivery (<37 gestation weeks) and small-for-gestational-age. RESULTS: Significant associations were found between physical work demands and low birthweight (< or =2500 g) and working with between a temporary contract and preterm delivery. Trends were also observed between working 40 hours or more a week and shift work, and birthweight of 3000 g or less. The study of a cumulative index showed that being exposed to at least two of these occupational factors significantly predicted birthweight of < or =3000 g (OR = 2.44, 95% CI: 1.17-5.08) and of < or =2500 g (OR = 4.65, 95% CI: 1.08-20.07) and preterm delivery (OR = 5.18, 95% CI: 1.00-27.01). CONCLUSIONS: Our findings suggest that occupational factors may predict birthweight through their predictive effects on preterm delivery. This is one of the few prospective studies on pregnancy outcomes that include working conditions. As they may be modifiable, occupational factors deserve more attention in relation to birth outcomes.

Low birthweight and preterm birth rates 1 year before and after the Irish workplace smoking ban.

OBJECTIVE: It is well-established that maternal smoking has adverse birth outcomes (low birthweight, LBW, and preterm births). The comprehensive Irish workplace smoking ban was successfully introduced in March 2004. We examined LBW and preterm birth rates 1 year before and after the workplace smoking ban in Dublin. DESIGN: A cross-sectional observational study analysing routinely collected data using the Euroking K2 maternity system. SETTING: Coombe University Maternal Hospital. POPULATION: Only singleton live births were included for analyses (7593 and 7648, in 2003 and 2005, respectively). METHODS: Detailed gestational and clinical characteristics were collected and analysed using multivariable logistic regression analyses and subgroup analyses. MAIN OUTCOME MEASURES: Maternal smoking rates, mean birthweights, and adjusted odds ratios (ORs) of LBW and preterm births in 2005 versus 2003. RESULTS: There was a 25% decreased risk of preterm births (OR, 0.75; 95% CI, 0.59-0.96), a 43% increased risk of LBW (OR, 1.43; 95% CI, 1.10-1.85), and a 12% fall in maternal smoking rates (from 23.4 to 20.6%) in 2005 relative to 2003. Such patterns were significantly maintained when specific subgroups were also analysed. Mean birthweights decreased in 2005, but were not significant (P=0.99). There was a marginal increase in smoking cessation before pregnancy in 2005 (P=0.047). CONCLUSIONS: Significant declines in preterm births and in maternal smoking rates after the smoking ban are welcome signs. However, the increased LBW birth risks might reflect a secular trend, as observed in many industrialised nations, and merits further investigations.

Fluorescence and coloration of grey hair.

Grey hair samples were collected from 11 individuals and separated into un-pigmented and pigmented fibres (International Hair Importers). Fluorescence measurements were obtained by using a double-grating fluorescence spectrophotometer and a bifurcated fibre optics accessory to measure the spectra directly from the surface of hair at various distances from the fibre root. Colour measurements were carried out by using a Hunter colorimeter. The fluorescence spectra of un-pigmented hair obtained by the excitation at 290 nm show a peak at 356 nm [tryptophan (Trp)], and multi-peak emissions in the range from 395 to 500 nm. A significant variation in the Trp emission intensity at 356 nm vs. the intensity of emission in the 395-500 nm range was observed for hair collected from various individuals with yellow coloured hair producing stronger relative emission in 395-500 nm range. Quantitative measurements of coloration and the calculation of the Yellowness Index (YI) showed linear correlation between YI and the ratio of fluorescence intensities I(440)/I(356) The spectra obtained by excitation at 320 nm showed the emission peaks at 395 nm (unidentified), 420 nm (N-formylkynurenine), 460 nm (kynurenine), and 495 nm (3-hydroxykynurenine), which are the products of oxidative or metabolic conversion of tryptophan. Un-pigmented, yellow hair showed a build-up of the fluorescence band corresponding to 3-hydroxykynurenine at 495 nm. The data also showed the fluorescence quenching effect of melanin resulting in the lowering of the fluorescence intensity of pigmented hair. The spectra obtained at various positions along the fibres demonstrated gradual photo-decomposition of hair chromophores during their lifetimes. This was indicated by a decrease of Trp fluorescence intensity, which was relatively fast (8.10(-4)-1.5.10(-3) [day(-1)] as calculated for hair obtained from various individuals) for un-pigmented hair and slower for pigmented hair. A decrease in Trp emission was accompanied by an increase in the yellow coloration toward the ends of un-pigmented fibres.