Embracing artificial intelligence- how can we make it inclusive and relevant for real world dermatological practice?

Artificial intelligence (AI) developments are rapidly advancing with algorithms capable of out-performing dermatologists in specific contrived challenges, but where prospective evaluation in real-world settings remain limited. Professional bodies have a role to encourage AI approaches to address clinical unmet needs, improve quality of care, and enhance patient experience without compromising safety. In 2019, the American Academy of Dermatology advocated principles of human-centred design for augmented intelligence innovations (1) emphasising the importance of synergy between dermatologist and the computer. More recently, the British Association of Dermatologists highlighted the weak current evidence-base supporting effectiveness of AI interventions in routine clinical practice and encouraged clinicians to independently evaluate the evidence prior to adoption (2).

Incidence of acute complications of herpes zoster among immunocompetent adults in England: a matched cohort study using routine health data

BACKGROUND

Herpes zoster can cause rare but serious complications; the frequency of these complications has not been well described.

OBJECTIVES

To quantify the risks of acute non-postherpetic neuralgia (PHN) zoster complications, to inform vaccination policy.

METHODS

We conducted a cohort study among unvaccinated immunocompetent adults with incident zoster, and age-, sex- and practice-matched control adults without zoster, using routinely collected health data from the UK Clinical Practice Research Datalink (years 2001 to 2018). Crude attributable risks of complications were estimated as the difference between Kaplan-Meier-estimated 3-month cumulative incidences in patients with zoster vs. controls. We used Cox models to obtain hazard ratios for our primary outcomes in patients with and without zoster. Primary outcomes were ocular, neurological, cutaneous, visceral and zoster-specific complications. We also assessed whether antivirals during acute zoster protected against the complications.

RESULTS

In total 178 964 incident cases of zoster and 1 799 380 controls were included. The absolute risks of zoster-specific complications within 3 months of zoster diagnosis were 0·37% [95% confidence interval (CI) 0·34-0·39] for Ramsay Hunt syndrome, 0·01% (95% CI 0·0-0·01) for disseminated zoster, 0·04% (95% CI 0·03-0·05) for zoster death and 0·97% (95% CI 0·92-1·00) for zoster hospitalization. For other complications, attributable risks were 0·48% (95% CI 0·44-0·51) for neurological complications, 1·33% (95% CI 1·28-1·39) for ocular complications, 0·29% (95% CI 0·26-0·32) for cutaneous complications and 0·78% (95% CI 0·73-0·84) for visceral complications. Attributable risks were higher among patients > 50 years old. Patients with zoster had raised risks of all primary outcomes relative to controls. Antiviral prescription was associated with reduced risk of neurological complications (hazard ratio 0·61, 95% CI 0·53-0·70).

CONCLUSIONS

Non-PHN complications of zoster were relatively common, which may affect cost-effectiveness calculations for zoster vaccination. Clinicians should be aware that zoster can lead to various complications, besides PHN.

Comparison of protoporphyrin IX accumulation and destruction during methylaminolevulinate photodynamic therapy of skin tumours located at acral and nonacral sites

BACKGROUND

Topical photodynamic therapy (PDT) is successful in the treatment of nonmelanoma skin cancers and associated precancers, but efficacy is significantly reduced in actinic keratosis lesions not located on the face or scalp.

OBJECTIVES

To compare the changes in protoporphyrin IX (PpIX) fluorescence in lesions undergoing routine methylaminolevulinate (MAL) PDT and the clinical outcome observed 3 months after treatment in lesions located at acral and nonacral sites.

METHODS

This study was a noninterventional, nonrandomized, observational study, which monitored changes in PpIX fluorescence in 200 lesions during standard dermatological MAL-PDT. These data were subsequently analysed in terms of lesions located at acral and nonacral sites.

RESULTS

Clinical clearance was significantly reduced (P < 0·01) in acral skin lesions when compared with lesions located at nonacral sites. The accumulation and destruction of PpIX fluorescence was significantly reduced in these acral lesions (P < 0·05 and P < 0·001, respectively). Specifically, lesion location at acral sites significantly reduced changes in PpIX fluorescence in actinic keratosis lesions during MAL-PDT (P < 0·01 and P < 0·05).

CONCLUSIONS

These data suggest that reduced PpIX accumulation and the subsequent reduction in PpIX photobleaching within acral lesions result in the reduced responsiveness of these lesions to MAL-PDT. Future work should therefore aim to improve photosensitizer accumulation/photobleaching within lesions located at acral sites.

Experience with a wipe guaiac-based faecal occult blood test as an alternative test in a bowel screening programme

The format of the traditional guaiac faecal occult blood test (gFOBT), particularly the collection technique, might cause difficulties for some. A multistage evaluation of alternative tests was performed. Firstly, four tests with different faecal collection approaches were assessed: a focus group recommended further investigation of a wipe gFOBT. Secondly, 100 faecal samples were analysed using two wipe tests and the routine gFOBT: no differences were found. Thirdly, a wipe gFOBT was introduced. Over 21 months, 400 requests were made and 311 wipe kit sets were submitted for analysis: 153 (49.2%) were negative, 21 (6.8%) positive (all 3 kits positive), 96 (30.9%) weak positive (1 or 2 positive) and 41 (13.2%) un-testable. Forty-three participants were referred for colonoscopy. Outcome data were provided on 39 participants: nine declined colonoscopy, two were judged unsuitable, two did not attend, two were already in follow-up, 13 had normal colonoscopy and two normal barium enema, two had diverticular disease, two had a metaplastic polyp, four had a low-risk adenoma and one had a high-risk adenoma. No participant had cancer. Detection of significant neoplasia was small. The use of the wipe gFOBT was ceased: it cannot be recommended as a screening test for bowel cancer.

A rare potentially treatable cause of bilateral optic disc swelling

Rapid onset bilateral optic disc swelling generally indicates an intracranial problem-that is, papilloedema. However, when there is also visual loss, disease affecting the optic nerves themselves must be considered. We present the diagnostic problem of a patient with optic disc swelling and progressive visual loss. Investigations finally revealed hypocalcaemia secondary to primary hypoparathyroidism. With treatment a marked improvement in vision occurred. This reversible rare cause of optic disc swelling should not be forgotten.

Fibrinolysis during anaphylaxis, and its spontaneous resolution, as demonstrated by thromboelastography

A large and ever-growing number of agents used in anaesthesia can precipitate acute anaphylactic reactions after their administration. Anaphylaxis is a sudden onset (or rapidly progressive), severe systemic allergic reaction, affecting multiple organ systems. The number of people who suffer severe systemic allergic reactions is increasing. The incidence is about 1-3 reactions per 10 000 population per annum, although anaphylaxis is not always recognized; therefore, certain UK studies may underestimate the incidence. In this case report, we present an episode of acute fibrinolysis associated with life-threatening anaphylaxis, demonstrated by thromboelastography (TEG) and resolving spontaneously. This is despite an added fibrinolytic insult in the form of cardiopulmonary bypass. There is a paucity of literature detailing fibrinolysis occurring during anaphylaxis, most likely due to the limited availability of TEG in the acute setting and the primary clinical focus of delivering life-saving interventions.

Atypical presentation of infiltrative thyroid dermopathy

A 46-year-old woman with Graves' disease developed infiltrative dermopathy of the thenar eminences. We believe this to be the first reported case of infiltrative dermopathy affecting the thenar eminences, and question whether repetitive occupational injury may have been a contributing factor. There is little published evidence to guide the treatment of infiltrative dermopathy.

Results from the first three rounds of the Scottish demonstration pilot of FOBT screening for colorectal cancer

OBJECTIVES

To assess the effects of the first three rounds of a pilot colorectal screening programme based on guaiac faecal occult blood testing (gFOBT) and their implications for a national population-based programme.

METHODS

A demonstration pilot programme was conducted in three Scottish NHS Boards. Residents aged between 50 and 69 years registered on the Community Health Index were included in the study.

RESULTS

In the first round, the uptake was 55.0%, the positivity rate was 2.07% and the cancer detection rate was 2.1/1000 screened. In the second round, these were 53.0%, 1.90% and 1.2/1000, respectively, and in the third round, 55.3%, 1.16% and 0.7/1000, respectively. In the first round, the positive predictive value of the gFOBT was 12.0% for cancer and 36.5% for adenoma; these fell to 7.0% and 30.3% in the second round and were maintained at 7.5% and 29.1% in the third round. The percentage of screen-detected cancers diagnosed at Dukes' stage A was 49.2% in the first round, 40.1% in the second round and 36.3% in the third round.

CONCLUSIONS

These results are compatible with those of previous randomised trials done in research settings, demonstrating that population-based colorectal cancer screening is feasible in Scotland and should lead to a comparable reduction in disease-specific mortality.

Pediatric preclinical testing program (PPTP) efficacy and pharmacodynamic evaluation of the Hsp90 inhibitor 17-DMAG

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Background: 17-DMAG is a small-molecule inhibitor of the protein chaperone HSP90 that is being developed as an anticancer agent because of the multiple HSP90 client proteins involved in cancer cell growth and survival. Methods: The PPTP includes an in vitro panel (n=27) as well as panels of xenografts (n=61) representing most of the common types of childhood solid tumors and childhood ALL. 17-DMAG was tested against the in vitro panel at concentrations from 1 nM to 10 microM and was tested against the in vivo tumor panels by IP administration using a 50 mg/kg BID twice weekly x 6 weeks dose and schedule. The PPTP’s 3 measures of antitumor activity were used (Houghton et al. Ped Blood Cancer 2006): 1) an objective response measure; 2) treated to control (T/C) tumor volume at day 21; and 3) a time to event (EFS T/C) measure. HSP70 induction was was used as a pharmacodynamic measure of HSP90 inhibition and was determined in tumor and liver tissue at 8 and 24 hours following the second of two doses of 17-DMAG (50 mg/kg IP) administered at 12 hour intervals. Results: 17-DMAG had an EC50 of 62 nM against the PPTP’s in vitro panel, with a trend for lower EC50 values for the rhabdomyosarcoma panel (median EC50 31 nM) compared to the remaining PPTP in vitro cell lines (p=0.06) and for higher EC50 values for the neuroblastoma lines (median EC50 396 nM, p=0.01). 17-DMAG induced significant differences in EFS distribution in 15 of 30 of the solid tumor xenografts, and in 4 of 6 of the evaluable ALL xenografts. Using the time to event activity measure, 17-DMAG had intermediate or high activity against 4 of 28 evaluable solid tumor xenografts (1 of 2 rhabdoid tumor and 3 of 4 alveolar rhabdomyosarcoma). The only objective response (a PR) observed was for an alveolar rhabdomyosarcoma xenograft. HSP70 induction was observed in both liver and tumor tissue, with robust induction (up to 450% increase versus control) occurring in both responding and non-responding tumors. Conclusions: 17-DMAG produced its greatest antitumor activity against alveolar rhabdomyosarcoma xenografts. Robust HSP70 induction was observed in both responding and non-responding xenografts, suggesting that tumor-specific downstream effects of HSP90 inhibition are primary determinants of response. (Supported by NCI NO1CM42216)

No significant financial relationships to disclose.

Intraindividual, right-left comparison of topical methyl aminolaevulinate-photodynamic therapy and cryotherapy in subjects with actinic keratoses: a multicentre, randomized controlled study

BACKGROUND

Actinic keratosis (AK), the most common premalignant skin condition, can represent a management challenge. Treatment should not only be effective, but also well tolerated and allow for good cosmesis on typical sun-exposed highly visible body sites.

OBJECTIVES

The primary objective was to compare the lesion response and subject preference for topical methyl aminolaevulinate (MAL)-photodynamic therapy (PDT) vs. cryotherapy for the treatment of AK.

METHODS

In this 24-week, multicentre, randomized, intraindividual (right-left) study, subjects received both one treatment session of MAL-PDT and a double freeze-thaw cryotherapy; the treatments were randomly allocated to either side of the face/scalp. Lesions with a noncomplete response were retreated after 12 weeks. The primary assessments were the subject's overall preference and lesion response at week 24. Secondary assessments included lesion response at week 12, cosmetic outcome, subject and investigator cosmetic outcome preference at week 24, and investigator overall preference at week 24. Skin discomfort and adverse events were also evaluated.

RESULTS

In total, 119 subjects with 1,501 lesions were included in the study. At week 12, treatment with MAL-PDT resulted in a significantly larger rate of cured lesions relative to cryotherapy (percentage lesion reduction from baseline: 86.9% vs. 76.2%; P < 0.001). At week 24, both treatment groups showed a high rate of cured lesions (89.1% for MAL-PDT vs. 86.1% for cryotherapy; P = 0.20; 95% confidence interval: -1.62 to 7.67). Results for subject and investigator preferences as well as cosmetic outcome favoured MAL-PDT. Both treatment regimens were safe and well tolerated.

CONCLUSIONS

The present study shows that, when treated with both MAL-PDT and cryotherapy, subjects significantly prefer MAL-PDT treatment for AK. MAL-PDT is an attractive treatment option for AK, with comparable efficacy and superior cosmetic outcomes compared with double freeze-thaw cryotherapy.

The national health demonstration projects

The White Paper Towards a Healthier Scotland pledged 15 million Pounds to support four national health demonstration projects to lead the way in achieving sustained improvement in child health, young people's sexual health, coronary heart disease and cancer. The Starting Well project aims to demonstrate that child health in Glasgow can be improved by a programme of activities which both supports families and provides them with access to enhanced community-based resources. The Healthy Respect project aims to help young people in Lothian develop a positive attitude to their own sexuality and that of others, and a healthy respect for their partners, in order to reduce unplanned teenage pregnancies and sexually transmitted infections. The Have a Heart Paisley project is targeting coronary heart disease among the population of Scotland's largest town. The Cancer Challenge project is piloting a screening programme in the North East of Scotland for the detection of colorectal cancer. Though each project has specific objectives, appropriate to its own topic, all share underlying principles. The projects will act as test beds for action and a learning resource for the rest of Scotland.

Cerebral arteriovenous malformation presenting as visual deterioration in a child

A rare case of visual loss as the presenting feature of a central arteriovenous malformation involving the vein of Galen is reported. A 5-year-old girl with a history of deteriorating vision for the past 6 months was examined. Ocular examination showed a left hemianopia, left optic atrophy, and dilated vessels of the right optic disc. MRI revealed a massive deep-seated central arteriovenous malformation involving the vein of Galen. The mechanism of visual loss is likely to be a combination of ischaemic optic atrophy associated with a steal phenomenon and direct compression of the right optic radiation.

Detection of mosaicism in amniotic fluid cultures: a CYTO2000 collaborative study

PURPOSE

To evaluate the assumptions on which the American College of Medical Genetics (ACMG) Standards and Guidelines for detecting mosaicism in amniotic fluid cultures are based.

METHODS

Data from 653 cases of amniotic fluid mosaicism were collected from 26 laboratories. A chi-square goodness-of-fit test was used to compare the observed number of mosaic cases with the expected number based on binomial distribution theory.

RESULTS

Comparison of observed data from the in situ colony cases with the expected distribution of cases detected based on the binomial distribution did not reveal a significant difference (P = 0.525).

CONCLUSIONS

The empirical data fit the binomial distribution. Therefore, binomial theory can be used as an initial discussion point for determining whether ACMG Standards and Guidelines are adequate for detecting mosaicism.

A case-control study of melanomas of the soles and palms (Australia and Scotland)

OBJECTIVES

Because the factors that influence risk of acral melanomas on the soles and palms in White populations are unknown, we investigated these in a multi-center case-control study.

METHODS

Cases of melanoma of the feet and hands diagnosed from 1987-93 in persons aged over 18 years were ascertained in eastern Australia and western Scotland. There were 275 cases of melanoma on the soles and palms matched to 496 controls (selected from the electoral roll) in Australia, and 36 cases matched to 72 controls (nominated by general practitioners) in Scotland.

RESULTS

Acral melanoma was strongly associated with high total body nevus counts (adjusted relative risk [RR] = 6.3, 95% confidence interval [CI] = 2.5-15.6), and with nevi on the soles (RR = 7.5, CI = 3.0-18.6). There were also significant positive associations with a penetrative injury of the feet or hands (RR = 5.0, CI = 3.0-8.6) and with heavy exposure to agricultural chemicals (RR = 3.6, CI = 1.5-8.3). Sun-sensitive complexions, cumulative sun exposure and a past history of nonmelanoma skin cancer were also associated with increased risk of acral melanoma. Current cigarette smoking was inversely related to acral melanoma (RR = 0.6, CI = 0.4-0.9).

CONCLUSIONS

Melanomas of the soles and palms resemble other cutaneous melanomas in their association with sun exposure, but are distinguished from them by their strong positive associations with nevi on the soles, previous penetrative injury, and exposure to agricultural chemicals, and by their inverse association with smoking.

Ropivacaine

Ropivacaine is a new aminoamide local anaesthetic drug. Its clinical profile is similar to that of bupivacaine but it causes less motor block and is less cardiotoxic.

Structure and chromosomal assignment of the human cathepsin K gene

Cathepsin K is a recently identified lysosomal cysteine proteinase that is the major protease responsible for bone resorption and remodeling. Mutations in this gene cause the sclerosing osteochondrodysplasia pycnodysostosis. To assess its evolutionary relatedness to other cysteine proteases and to facilitate mutation identification in patients with pycnodysostosis, a genomic clone, 74e16, containing the cathepsin K gene was isolated from a human PAC library, and the cathepsin K genomic structure was determined. The cathepsin K gene contained eight exons and spanned approximately 9 kb. The transcription initiation site, determined by primer extension analysis, was 169 nucleotides upstream from the translation initiation site. The 5'-flanking region lacked a TATA box but contained two AP1 sites. Comparison of genomic and cDNA sequences suggested that this flanking sequence may be the major promoter in osteoclasts and macrophages. Cathepsin K was mapped to chromosome 1q21 by fluorescence in situ hybridization and found to reside within 150 kb of an evolutionarily related cysteine protease, cathepsin S. These findings expand our understanding of the papain family lysosomal cysteine proteases and should facilitate mutation analysis in pycnodysostosis.

Phylogenetic relationships of Lecythidaceae: a cladistic analysis using rbcL sequence and morphological data

This study examined in detail the rbcL sequence and morphological support for subfamilial relationships and monophyly of Lecythidaceae. Initially we needed to establish relationships of Lecythidaceae among other dicot families. To complete this we examined 47 rbcL sequences of 25 families along with molecular observations from several large analyses of rbcL data. All analyses strongly support the monophyly of the asterid III grouping. This analysis revealed Lecythidaceae to be paraphyletic and indicated potential outgroup relationships with Sapotaceae. Once relationships had been evaluated using molecular data we then concentrated on analyzing separate and combined morphological and molecular databases. The topology of the morphological data set was similar to the rbcL sequence and combined data sets except for the positioning of Napoleonaeoideae, Grias, Gustavia, and Oubanguia. According to the combined results, Planchonioideae, Lecythidoideae. and Foetidioideae are monophyletic, whereas the subfamily Napoleonaeoideae are paraphyletic. Nested within Napolconaeoideae, we found Asteronthos forms a strongly supported clade with Oubanguia (Scytopetalaceae). Foetidia, the only genus of Foetidioideae, is sister to Planchonioideae, and this clade is sister to Lecythidoideae. The [(Planchonioideae, Foetidioideae) Lecythidoideae are sister to Asteranthos/Oubanguia. Napoleonaeoideae are sister to the rest of Lecythidaceae.

Stimulated mitogen-activated protein kinase is necessary but not sufficient for the mitogenic response to angiotensin II. A role for phospholipase D

Activation of the mitogen-activated protein kinase (MAPK) cascade has been widely associated with cell proliferation; previous studies have shown that angiotensin II (AII), acting on 7-transmembrane G protein-coupled receptors, stimulates the MAPK pathway. In this report we investigate whether the MAPK pathway is required for the mitogenic response to AII stimulation of vascular smooth muscle cells derived from the hypertensive rat (SHR-VSM). AII stimulates the phosphorylation of MAPK, as determined by Western blot specific for the tyrosine 204 phosphorylated form of the protein. This MAPK phosphorylation was inhibited by the presence of the inhibitor of MAPK kinase activation, PD 098059. Using a peptide kinase assay shown to measure the p42 and p44 isoforms of MAPK, the stimulated response to AII was inhibited by PD 098059 with an IC50 of 15.6 +/- 1.6 microM. The AII stimulation of [3H]thymidine incorporation was inhibited by PD 098059 with an IC50 of 17.8 +/- 3.1 microM. PD 098059 had no effect on AII-stimulated phospholipase C or phospholipase D (PLD) activity. When the SHR-VSM cells were stimulated with phorbol ester, there was an activation of MAPK similar in size and duration to the response to AII, but there was no significant enhancement of [3H]thymidine incorporation. There was also no activation of PLD by phorbol ester, while AII produced a robust PLD response. Diversion of the product of the PLD reaction by 1-butanol caused a partial loss of the [3H]thymidine response; this did not occur with tertiary butanol, which did not interfere with the PLD reaction. These results show that in these cells the MAPK cascade is required but not sufficient for the mitogenic response to AII, and suggest that the full mitogenic response requires both MAPK in conjunction with other signaling components, one of which is PLD.

Systemic effects of screening for retinopathy of prematurity

AIMS

To detect systemic complications of screening for retinopathy of prematurity (ROP), paying particular attention to the physical examination.

METHODS

Oxygen saturation, pulse rate, and blood pressure were monitored before, during, and after 110 ROP screening examinations.

RESULTS

Following topical mydriatics diastolic blood pressure was elevated by a mean of 6 (SD 7.2) mm Hg. Immediately after the examination there was a further rise in both systolic and diastolic pressure of 4.3 (14.5) mm Hg and 3.3 (11.6) mm Hg, respectively. Oxygen saturation and pulse rate remained stable during the control period and administration of eyedrops. Saturation fell by a median of 3% (95% confidence interval plus or minus 1.2%) after the examination while there was rise in pulse rate of 7 (SD 23.1) beats per minute. This change in pulse rate was not observed in infants on concurrent methylxanthine therapy. No infant had clinically significant changes at the end of the study.

CONCLUSION

The initial changes in blood pressure may represent side effects of topical mydriatics but the later changes following the physical examination may be an additional response to the stress of ROP screening.

Stimulation of two vascular smooth muscle-derived cell lines by angiotensin II: differential second messenger responses leading to mitogenesis

1. We show here that angiotensin II (AII) and endothelin-1 (ET-1) stimulate [3H]-thymidine incorporation in a smooth muscle cell line derived from aortae of spontaneously hypertensive rats (SHR), but not in cells derived from normotensive controls (WKY). We have used the differential response of the two cell lines to investigate the relationship between second messenger systems and the mitogenic response. 2. AII produced an increase in accumulation of inositol 1,4,5-triphosphate which was greater in the SHR-derived cell line than in the WKY cells. 3. AII gave an increase in cytosolic Ca2+ in each of the cell lines, with both a larger peak (15-30 s) and plateau response (2 min) in the SHR cells. ET-1 gave an enhanced response in the SHR-derived cells with respect to the peak but not the plateau of cytosolic Ca2+. 4. Phospholipase D activity was studied by monitoring the formation of [3P]-phosphatidylbutanol in 32Pi prelabelled cells. AII stimulation gave a larger phospholipase D response in the SHR-derived cells, while ET-1 gave a larger response in WKY-derived cells. 5. Stimulation of SHR-derived cells with 100 nM AII for 1 h, followed by 19 h in the absence of agonist, stimulated [3H]-thymidine incorporation over the next 4 h. When the 1 h stimulation with AII was in the presence of increasing concentrations of butanol, which diverts the product of the phospholipase D pathway, there was a loss of stimulated [3H]-thymidine incorporation which was significant at 10 mM butanol and at 30-50 mM reached a maximum loss of 40%. 6. Contrasting with this there was no apparent loss of ET-l-stimulated thymidine incorporation when butanol was present at concentrations up to 40 mM.7. These results suggest that phospholipase D is one of several pathways in the mitogenic response of SHR-derived vascular smooth muscle cells to All.

Effects of nitrous oxide on psychological performance. A dose-response study using inhalation of concentrations up to 15%

In this six-period randomised double-blind study, 12 healthy volunteers inhaled mixtures of nitrous oxide at concentrations of 0% (placebo); 3%, 5%, 7%, 10%, and 15% in oxygen. Each concentration was inhaled for 55 min, each period being on a separate day. The order of treatments was randomised using a Latin-Square design. The effects of nitrous oxide were assessed using a battery of performance tests which included measures of attention, psychomotor function, memory and cognition. Mood was assessed using visual analogue scales. Measures of attention and psychomotor performance showed impairment at 15% nitrous oxide, and subjective measures showed sedation at this dose. The Buschke Selective Reminding Task showed impairment to long-term recall at all doses of nitrous oxide compared to placebo, while short-term recall was impaired only at 15%. These results suggest that consolidation of memory may be particularly sensitive to disruption as a result of CNS depression.

A study of chromium induced allergic contact dermatitis with 54 volunteers: implications for environmental risk assessment

Over the past 60 years, dose-response patch test studies by various methods have been conducted in an attempt to identify the minimum elicitation threshold (MET) concentration of hexavalent chromium (Cr(VI)) that produces an allergic response in Cr(VI) sensitive subjects. These data are not adequate, however, to provide an accurate estimate of the MET because of the variability in the patch testing techniques and the variability in diagnostic criteria used. Furthermore, the data were not reported in terms of mass of allergen per surface area of skin (mg Cr/cm2-skin), which is necessary for conducting occupational or environmental health risk assessments. Thus the purpose of this study was to determine the MET (mg allergen/cm2) for Cr(VI) and trivalent chromium (Cr(III)) by patch testing techniques. A patch test method that delivers a controlled amount of allergen per surface area of skin was used. A group of 54 Cr(VI) sensitised volunteers were patch tested with serial dilutions of Cr(VI) and Cr(III) to determine the cumulative response rate at several concentrations. The results indicate that the 10% MET for Cr(VI) based on the cumulative response was 0.089 micrograms Cr(VI)/cm2-skin. Only one of the 54 volunteers may have responded to 33 micrograms Cr(III)/cm2-skin, otherwise Cr(III) was unable to produce allergic contact dermatitis in these highly sensitive volunteers. Two supplemental studies were also conducted to assess whether the surface area of the patch and the concentration of Cr(VI) in the patch (related to patch thickness) were likely to influence the results. The data from these studies were used to assess the risk of developing allergic contact dermatitis due to contact with Cr(VI) and Cr(III) in soil. The findings indicated that soil concentrations at least as high as 450 ppm Cr(VI) and 165,000 ppm Cr(III) should not pose an allergic contact dermatitis hazard for at least 99.99% of the people in the community who might be exposed.

Measurement of cremophor EL following taxol: plasma levels sufficient to reverse drug exclusion mediated by the multidrug-resistant phenotype

BACKGROUND

Paclitaxel (Taxol) is the first of a new class of cytotoxic agents with activity against tumors resistant to other drugs. For clinical use, paclitaxel is currently formulated in a vehicle of 50% ethanol and 50% polyethoxylated surfactant Cremophor EL (Cremophor). We have previously shown that Cremophor will block the P-glycoprotein drug efflux pump responsible for the multidrug-resistant phenotype. Overexpression of P-glycoprotein is one mechanism of in vitro resistance to a number of currently used cytotoxic agents including paclitaxel.

PURPOSE

Our aim was to develop a bioassay to measure plasma levels of Cremophor and to determine whether or not plasma levels of Cremophor achieved during paclitaxel therapy are sufficient to inhibit the activity of the P-glycoprotein.

METHODS

All patients studied had histologically proven, advanced ovarian carcinoma with measurable or evaluable disease and had received at least one prior platinum-containing regimen. The bioassay used flow cytometry to measure the increase in equilibrium intracellular daunorubicin levels in multidrug-resistant human T-cell leukemia cells (CEM/VLB100) in the presence of a series of concentrations of Cremophor. Levels of Cremophor were measured in plasma from 21 patients after a 3-hour infusion of 135 or 175 mg/m2 paclitaxel. Both dose levels were given following premedication with oral dexamethasone, intravenous promethazine hydrochloride, and intravenous cimetidine. The Cremophor bioassay involved incubation of CEM/VLB100 cells (5 x 10(5)) for 1 hour with 2 micrograms/mL daunorubicin in 0.5 mL HL-1 medium plus 0.5 mL plasma prior to flow cytometric analysis. Pretreatment plasma was used to derive a standard curve for the effect of Cremophor on equilibrium daunorubicin levels. All measurements were done in triplicate.

RESULTS

In vitro experiments indicated that, for maximal inhibition of P-glycoprotein activity, concentrations of Cremophor of 0.1% (vol/vol) were required. At the end of a 3-hour infusion of paclitaxel, plasma levels of Cremophor in 19 of 21 patients were 0.1% or higher and 0.09% in the remaining two. Concentrations of 5-20 microM paclitaxel dissolved in ethanol without Cremophor did not inhibit P-glycoprotein in this assay.

CONCLUSION

The concentrations of Cremophor measured in plasma drawn from patients after a 3-hour infusion of paclitaxel at 135 or 175 mg/m2 were found to be sufficient to inhibit P-glycoprotein activity in vitro.

IMPLICATIONS

The efficacy of paclitaxel against some tumors may be aided by its administration in a vehicle solution containing Cremophor in quantities that reach concentrations in the plasma sufficient to reverse multidrug resistance of neoplastic cells.