bluuebunny/crossref_metadata_2025 huggingface dataset:
Altered Pharmacokinetics and Metabolism of Valproate after Replacement of Conventional Valproate with the Slow‐Release Formulation in Epileptic Patients
Authors: Kondo Tsuyoshi , Tokinaga Noboru , Suzuki Akihito , Ono Shingo , Yabe Hirooki , Kaneko Sunao , Hirano Takayuki
Published: March 2003

Abstract: Altered metabolism of valproate has been suggested as the mechanism of teratogenicity and hepatotoxicity of valproate. This study aimed at examining whether pharmacokinetics of a slow‐release formulation of valproate affects valproate metabolism. Thirty‐one epileptic patients were treated with fixed‐doses of conventional valproate for at least 2 months. Thereafter, the drug was replaced with the same doses of slow‐release formulation of valproate for 2 months. Blood samplings for determination of valproate and its metabolites by gas chromatography‐mass spectrometry were performed at three time‐points (just before morning dose and at 1 and 5 hr after morning dose) during both treatment phases. There was a significant difference (P<0.005) in the mean serum concentration (±S.D.) of valproate after 1 hr between conventional valproate (63.1±27.9 μg/ml) and slow‐release formulation of valproate (45.7±19.5 μg/ml). Mean serum concentrations (±S.D.) of 4‐en and hydroxy metabolites after 5 hr were significantly reduced after replacement with slow‐release formulation of valproate (4‐en: 29.5±14.0→23.0±15.3 ng/ml, 3‐OH: 488.5±234.0→419.6±171.1 ng/ml, 4‐OH: 404.3±124.7→342.8±147.6 ng/ml, 5‐OH: 102.8±54.4→81.0±43.6 ng/ml). The present study suggests that smaller diurnal fluctuations in valproate concentrations during treatment with slow‐release formulation of valproate result in decreased formations of minor metabolites including 4‐en, the most toxic metabolite.
Eumelanin is a Major Determinant for2‐Amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP) Incorporation into Hair of Mice
Authors: Hegstad Solfrid , Reistad Ragnhild , Haug Line S. , Alexander Jan
Published: March 2003

Mice with different hair pigmentation were studied to evaluate the role of melanin in the incorporation of 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP) into hair. Mice C57BL/6J‐c2j/+ (white), C57BL/6J‐Ay (yellow), C57L/J (grey), C57BR/cdJ (brown) and C57BL/6J (black) were dosed with PhIP: 7–9 days old (total amount: 0.006 or 0.58 mg/kg b.wt., for 4 days) and adults (total amount 50 mg/kg b.wt. during 8 weeks). Hair was collected either 30 days after the last PhIP administration (new‐born mice) or 8 weeks after the first administration (adult mice). PhIP was incorporated into black hair to a greater extent than into brown, grey, yellow and non‐pigmented hair. The concentration of PhIP in the hair of new‐born mice exposed to 0.58 mg PhIP/kg b.wt. were (mean±S.D.): 328±135 (black), 134±41 (brown), 9.1±1.2 (yellow) and 5.2±1.4 (white) ng/g hair. The PhIP concentrations in the hair of adult mice exposed to 50 mg/kg b.wt. were: 4750±1449 (black), 810±235 (brown), 541±119 (grey), 35.5±4.6 (yellow) and 21.6±8.8 (white) ng/g, and the eumelanin hair concentration in the same animals decreased in a similar pattern. A linear relationship (r2=1.00, P<0.0001) between the relative PhIP incorporation and the eumelanin concentration in hair was found.
Regional Differences in the Effect of Oestrogen on Vascular Tone in Isolated Rabbit Arteries
Authors: Opgaard Ole Saetrum , Duckles Sue P. , Krause Diana N.
Published: March 2003

Abstract: The aim of the study was to assess how oestrogen acutely affects the tone of isolated artery segments from different vascular beds in rabbit. Cumulative concentrations of 17β‐oestradiol were added to ring segments of thoracic aorta, pulmonary artery, ear artery and coronary arteries from adult male rabbits. Coronary arteries precontracted with potassium or the thromboxane agonist, U46619, relaxed to oestrogen (10−7 to 10−4 M), whereas oestrogen (10−8 to 10−4 M) only caused additional contraction in segments of thoracic aorta and pulmonary artery precontracted with phenylephrine. In the thoracic aorta both the phospholipase C inhibitor NCDC (10−4 M) and the cyclooxygenase inhibitor indomethacin (10−5 M) almost completely blocked the contractile effect of oestrogen. In segments of the ear artery, oestrogen caused relaxation only at higher concentrations of oestrogen (10−5 to 10−4 M). In conclusion, oestrogen may cause both relaxation and vasoconstriction in different vascular beds, and in the thoracic aorta the contractile effects of oestrogen may be mediated via inositol phosphate‐dependent pathways and release of prostaglandins.
Dose Response of Carboplatin‐Induced Nephrotoxicity in Rats
Authors: Husain Kazim , Jagannathan Ramesh , Hasan Zeshan , Trammell Gary L. , Rybak Leonard P. , Hazelrigg Stephen R. , Somani Satu M.
Published: March 2003

Abstract: Carboplatin, a second‐generation platinum‐containing anticancer drug, is currently being used against a variety of cancers. High‐dose carboplatin chemotherapy can cause renal tubular injury in cancer patients. However, the biochemical mechanism of carboplatin‐induced renal injury has not been well studied. This study investigated the dose response of carboplatin‐induced changes in endogenous antioxidants, lipid peroxidation and platinum content in rat kidney. Male Wistar rats (250–300 g) were divided into five groups and treated as follows: (1) control (saline, intraperitoneally); (2) carboplatin (64 mg/kg, intraperitoneally); (3) carboplatin (128 mg/kg, intraperitoneally); (4) carboplatin (192 mg/kg, intraperitoneally); and (5) carboplatin (256 mg/kg, intraperitoneally). The animals were sacrificed four days after treatment. The blood and kidneys were isolated and analyzed. Plasma creatinine and blood urea nitrogen levels were increased significantly in response to carboplatin in a dose‐dependent manner. Renal superoxide dismutase and catalase activities were decreased significantly due to carboplatin at dosages of 128 mg/kg and above. The protein expressions of renal copper/zinc‐superoxide dismutase and manganese‐superoxide dismutase significantly depleted after carboplatin. Carboplatin (192 and 256 mg/kg) significantly increased lipid peroxidation (malondialdehyde concentration) in rat kidneys. Carboplatin dose‐dependently increased the renal platinum concentration, with significance at dosages of 128 mg/kg and above. Carboplatin (256 mg/kg) significantly increased renal xanthine oxidase activity, while ratio of reduced to oxidized glutathione depleted significantly. The data suggested that carboplatin caused dose‐dependent oxidative renal injury, as evidenced by renal antioxidant depletion, enhanced lipid peroxidation, platinum content, plasma creatinine and blood urea nitrogen levels in rats.
Iron Absorption: Biochemical and Molecular Insights into the Importance of Iron Species for Intestinal Uptake
Authors: Cremonesi Piero , Acebron Alvaro , Raja Kishor B. , Simpson Robert J.
Published: March 2003

Abstract: Recent advances in cloning of proteins involved in intestinal iron absorption can inform design and understanding of therapeutic iron preparations. Redox chemistry of iron is particularly important in iron metabolism, both as a potential source of toxic intermediates and as an essential requirement for efficient iron transport. The initial step in iron absorption (uptake from lumen to mucosa) is particularly important and several pathways involving Fe(III) reduction or transport and Fe(II) transport have been identified. Novel genes associated with iron uptake include Dcytb, a putative iron‐regulated reductase and DMT1, a Fe(II) carrier in the brush border membrane. Other mechanisms may also operate, however. We review the recent findings and apply this to understanding the absorption of Fe(III) pharmaceuticals.
Multiple Thrombotic Occlusions of Vessels after Russell's Viper Envenoming
Authors: Hung Dong‐Zong , Wu Ming‐Ling , Deng Jou‐Fang , Yang Dar‐Yu , Lin‐Shiau Shoei‐Yn
Published: March 2003

Abstract: Systemic bleeding due to consumption coagulopathy and thrombocytopenia due to activation of procoagulants is the leading manifestation and cause of death in Russell's viper systemic envenoming. Thrombotic occlusion of the blood vessels is rare in cases of snakebite. In this report, two adult patients with Russell's viper systemic envenoming presented multiple cerebral infarctions, digital gangrenes and ischaemic organs in addition to typical clinical manifestations of bleeding diathesis and renal involvement. Our findings in these two special cases suggest that the venom‐induced coagulopathy and endothelium damage, predisposed by toxin‐induced vasoconstriction, might be the possible mechanism of multiple thrombotic vascular occlusions in systemic envenoming of Formosan Russell's viper.
Human Pancreatic Acinar Cells Do Not Respond to Cholecystokinin
Authors: Ji Baoan , Bi Yan , Simeone Diane , Mortensen Richard M. , Logsdon Craig D.
Published: March 2003

Abstract: Pancreatic secretion can be influenced by cholecystokinin (CCK) either directly via actions on acinar cells or indirectly via actions on nerves. The presence and functional roles of CCK receptors on human pancreatic acinar cells remains unclear. In the current study human pancreatic acini were isolated and then treated with CCK‐8, gastrin and/or carbachol. Functional parameters were measured including intracellular [Ca2+] and amylase secretion. It was observed that human acini did not respond to CCK agonists but did respond to carbachol with robust increases in functional parameters. Adenoviral‐mediated gene transfer of CCK1 or CCK2 receptors to the human cells resulted in cell responses to CCK agonists. In order to determine the reason for the lack of responsiveness of the human acini, expression of receptor mRNAs was determined using quantitative RT‐PCR and localized by in situ hybridization. mRNA levels for CCK1 receptors were ∼30 times lower than those of CCK2 receptors, which were ∼10 times lower than those of m3 Ach receptors as measured by quantitative PCR. Neither CCK1 nor CCK2 receptors were localized in adult human pancreas by in situ hybridization. These results indicate that human pancreatic acinar cells do not respond directly to CCK receptor activation and this is likely due to an insufficient level of receptor expression.
Polychromatic phototest as a prognostic tool for polymorphic light eruption
Authors: Leroy D. , Dompmartin A. , Faguer K. , Michel M. , Verneuil L.
Published: March 2003

Background: Diagnosis of polymorphic light eruption (PLE) is based on the patient’s history, the morphology of the lesions and the results of phototesting. Skin lesions of PLE can be provoked by repetitive UVB or UVA irradiation. However, about 20% of the patients with PLE have negative phototests. As 24% of the patients with PLE go into remission, it was of interest to search for a link between the results of the phototests and the evolution of the photodermatosis.

Methods: Forty patients with PLE were recruited and repetitive phototests were performed. To ensure a good reproducibility of the phototests, one to three phototests were performed on each patient at different stages of the disease including the period when the PLE had gone into remission.

Results: Except for one patient, there was a good reproducibility of the repetitive polychromatic phototests: in each patient, the tests remained positive or negative throughout the disease. After long‐term follow‐up, two different subgroups were identified: 30 patients with active PLE and 10 patients in remission. There were no clinical differences between these two groups apart from the age of onset and the clinical lesions of the PLE. PLE began at an earlier age in the patients in remission and presented mainly with a plaque‐type eruption. In total, 52.5% of the patients had at least one positive polychromatic phototest. Phototests were positive only in patients with active disease. All the patients in remission had negative phototests.

Conclusions: Repetitive phototests could be a prognostic marker for PLE. Two subtypes of PLE were identified on the basis of phototest results: the benign form of PLE with negative phototests, which tends to go into remission, and the more severe and more chronic PLE, with positive phototests.
Ultraviolet‐filtering properties of commonly used tissue cell culture plasticware
Authors: Brown Douglas B. , Peritz Adam E. , Uitto Jouni , Gasparro Francis P.
Published: March 2003

Background: Fluorescent sunlamps are a common source of ultraviolet radiation (UVR) for photobiology research. However, these lamps emit a significant amount of biologically “irrelevant” wavelengths that, if not removed, can drastically skew results and perhaps lead to mistaken conclusions regarding human photobiology. The use of a cellulose triacetate sheet (Kodacel) to filter the shorter ultraviolet wavelengths has become the accepted standard in photobiology. Over time, the transmission characteristics of this sheet may be altered due to photochemical changes. In addition, in vitro experiments utilizing filtered fluorescent sunlamps require the removal of plastic tissue cell culture lids, increasing the possibility of contamination.

Methods: We evaluated the transmission characteristics of various commercially available plastic lids used in tissue cell cultures. In addition, we used a biological system containing the human elastin promoter/chloramphenicol acetyltransferase reporter gene construct to compare the effects of filtering from these plastic lids.

Results: Here, we demonstrate that the transmission of UVR and the biological response through plastic culture dish lids is similar to that of Kodacel.

Conclusion: Although this is an improvement for in vitro experiments, further improvements can be made using more realistic UVR sources, e.g. UVA‐340 lamps, which mimic the short wavelengths of sunlight.
Skin aging induced by ultraviolet exposure and tobacco smoking: evidence from epidemiological and molecular studies
Authors: Yin Lei , Morita Akimichi , Tsuji Takuo
Published: March 2003

Background: Tobacco smoking, similar to ultraviolet (UV) A radiation exposure, has previously been identified as an important factor contributing to premature aging of human skin.

Objective and design:

To investigate the relationship between these two environmental factors, we have conducted a cross‐sectional study of 83 subjects (48 males, 35 females, age range 23–95), in which sun exposure, pack‐years of smoking history and potential confounding variables were assessed by questionnaire. Facial wrinkles were quantified using the Daniell score. In order to study the molecular mechanism by which smoking caused wrinkle formation, in vitro studies were conducted to assess the alteration of matrix metalloproteinase‐1 (MMP‐1) mRNA expression in human fibroblasts stimulated with tobacco smoke extract or/and UVA.

Results: Logistic statistic analysis of the data revealed that age [odds ratio (OR)=7.5, 95% confidence interval (CI)=1.87–30.16], pack‐years (OR=5.8, 95% CI=1.72–19.87), and sun exposure (OR=2.65, 95% CI=1.0–7.0) independently contributed to facial wrinkle formation. When excessive sun exposure (>2 h/day) and heavy smoking (35 pack‐years) occurred together, the risk for developing wrinkles was 11.4 times higher than that of non‐smokers and those with less sun exposure (<2 h/day) at the same age. The in vitro studies revealed that MMP‐1 expression was significantly increased in fibroblasts after the stimulation with either tobacco smoke extract or UVA. Maximum induction was observed when cells were treated with tobacco smoke extract plus UVA, indicating that the two factors act in an additive manner. MMP‐1 induction was significantly higher in the low glutathione (GSH) content fibroblast compared to that in the high GSH fibroblast, indicating that the differences in glutathione content define the susceptibility of fibroblasts towards UV‐ or tobacco smoking‐induced MMP‐1 expression.

Conclusion: Tobacco smoke and UVA cause wrinkle formation independently of each other. We propose that both factors cause aging of human skin through additive induction of MMP‐1 expression.
Photoonycholysis
Authors: Baran Robert , Juhlin Lennart
Published: March 2003

Background/Purpose: Photoonycholysis may be seen as a part of Segal's triad, photosensitivity followed by discoloration of the nails and onycholysis. But the latter may also appear, independently, in the absence of photosensitive reaction elsewhere.

Methods: Photoonycholysis may result from drug intake, porphyria cutanea tarda, erythropoietic porphyria, erythropoietic protoporphyria, variegate porphyria and pseudoporphyria. Rarely, spontaneous photoonycholysis may be observed.

Results: Four distinct subtypes have been recorded without relationship between the responsible drugs and the different clinical varieties of photoonycholysis. Primary photohemorrhage can occur; it can also be associated with polydactylous photoonycholysis type III.

Conclusion: The inability to reproduce photoonycholysis experimentally should be emphasized.
The effect of melatonin on in vitro fertilization and embryo development in mice
Authors: Ishizuka Bunpei , Kuribayashi Yasushi , Murai Kunihiko , Amemiya Akira , Itoh Masanori T.
Published: March 2003

To examine the effect of melatonin on in vitro fertilization and embryonic development, mouse embryos after insemination in vitro were cultured in a physiological medium with or without melatonin. Melatonin increased the fertilization rate significantly at a concentration between 10−6 and 10−4 M (27.6 vs. 43.9 or
40.4%, P<0.01). Furthermore, a significant increase in the rate
of embryos reaching the four‐cell stage (16.0 vs. 26.7%,
P<0.01), the eight‐cell stage (12.1 vs. 25.8 or 23.5%,
P<0.01), and blastulation (8.9 vs. 23.5 or 17.5%,
P<0.01) was observed when the embryos were cultured in a medium
containing 10−8 or 10−6 M melatonin. These results demonstrate that melatonin supports fertilization and early embryo development after in vitro fertilization.
Melatonin, vitamin E, and estrogen reduce damage induced by kainic acid in the hippocampus: potassium‐stimulated GABA release
Authors: Ortiz Genaro G. , Sánchez‐Ruiz Mayra Y. , Tan Dun‐Xian , Reiter Russel J. , Benítez‐King Gloria , Beas‐Zárate Carlos
Published: March 2003

Melatonin, vitamin E and estrogen have been shown to exert neuroprotective effects against kainic acid (KA)‐induced damage in the hippocampus. The aim of the present study was to examine the changes in potassium‐evoked γ‐aminobutyric acid (GABA) release in the hippocampus of KA‐treated rats and to test the possible protective effects of melatonin, vitamin E or estrogen. Following the treatment of mice with KA, a marked reduction in potassium‐evoked [3H]GABA release was observed. Melatonin or estrogen prevented the reduction in potassium‐evoked GABA release due to kainate administration. Vitamin E also exhibited some protective effect, but it was less than that provided by melatonin or estrogen. Melatonin, estrogen and, to a lesser extent, vitamin E reduce the physiological toxicity of KA. Since KA is believed to cause neuronal alterations via oxidative processes, it is assumed that the free radical scavenging and oxidative properties of melatonin, estrogen and vitamin E account for the protective effects of these agents.
Melatonin rhythms in European sea bass plasma and eye: influence of seasonal photoperiod and water temperature
Authors: García‐Allegue R. , Madrid J.A. , Sánchez‐Vázquez F.j
Published: March 2003

The transduction of seasonal information from the environment (i.e., photoperiod and water temperature) into melatonin rhythms was studied in sea bass. Plasma and ocular melatonin (N‐acetyl‐5‐methoxytryptamine) was determined in autumn, winter, spring and summer (experiment 1) under natural culture conditions, and in the summer and winter solstices under both natural and “6‐month out‐of‐phase” photoperiods (experiment 2). At each sampling, 48 sea bass were sacrificed at a rate of 6 fish every 3 hr and the level of melatonin was determined in plasma and eye cup samples by ELISA. In experiment 1, significant diel changes were observed in plasma melatonin, with nocturnal melatonin varying from 144 pg/mL (summer) to 23 pg/mL (autumn), while diurnal melatonin remained low, around 8 pg/mL throughout the year. In experiment 2, the photoperiod length was shown to control the duration of the nocturnal melatonin rise, while the water temperature determined the amplitude of the melatonin rhythm. Ocular melatonin peaked during daytime in autumn and winter, but no significant changes were detected in summer and spring. In conclusion, plasma melatonin rhythms in sea bass reflect the pineal capacity to integrate seasonal information and supply precise calendar information, which may synchronize different physiological processes such as annual reproduction and feeding rhythms.
Neuroprotection by melatonin against ischemic neuronal injury associated with modulation of DNA damage and repair in the rat following a transient cerebral ischemia
Authors: Sun Feng‐Yan , Lin Xiang , Mao Li‐Zhen , Ge Wei‐Hong , Zhang Ling‐Mei , Huang Ya‐Lin , Gu Jin
Published: March 2003

In the present study, double fluorescence staining combined with confocal laser scanning microscopy analysis were used to examine the effects of melatonin on ischemia‐induced neuronal DNA strand breaks and its possible mechanisms in a transient middle cerebral artery (MCA) occlusion model. Results showed that melatonin dose‐dependently reduced infarct areas and decreased both DNA double and single strand breaks (DSB and SSB) and enhanced cell viability in the peri‐ischemic brain regions. Furthermore, Bcl‐2 induction in the ischemic brain was further enhanced by melatonin treatment. Double staining analysis indicated that the cells costained for Bcl‐2 and TdT‐mediated–deoxyuridine triphosphate (dUTP) nick‐end labeling (TUNEL), a DSB marker, displayed a relative regular morphology compared with the cells only stained with TUNEL. Transient ischemia induced an expression of excision repair cross‐complementing factor 6 (ERCC6) mRNA, a gene essential for the preferential repair of nuclear excision repair, in the injured neurons. Double labeling showed that ERCC6 only co‐localized with proliferating cell nuclear antigen (PCNA), a member of the nuclear excision repair complex, but not with TUNEL. Melatonin further and statistical significantly up‐regulated ERCC6 mRNA expression in the peri‐ischemic region of rat brains. The results suggest that neuroprotection by melatonin against ischemic injury may be related to modulation of apoptosis and DNA repair capacity.
Protective effect of melatonin and its precursor L‐tryptophan on acute pancreatitis induced by caerulein overstimulation or ischemia/reperfusion
Authors: Jaworek Jolanta , Leja‐Szpak Anna , Bonior Joanna , Nawrot Katarzyna , Tomaszewska Romana , Stachura Jerzy , Sendur Ryszard , Pawlik Wiesław , Brzozowski Tomasz , Konturek Stanisław J.
Published: March 2003

Abstract: Melatonin, a pineal secretory product, synthesized from l‐tryptophan, has received increased attention because of its antioxidative and immunomodulatory properties. It has been detected in the gut and shown to protect the gastric mucosa, and liver from acute damage, but the role of melatonin in the protection of the pancreas against acute inflammation is not clear. The aim of this study was to investigate the effects of melatonin and its precursor, l‐tryptophan, on caerulein‐induced pancreatitis (CIP) and on ischemia/reperfusion (I/R)‐provoked pancreatitis in rats. CIP was induced by subcutaneous infusion of caerulein to the rats (25 μg/kg). I/R was induced by clamping of the inferior splenic artery for 30 min followed by 2 hr of reperfusion. Melatonin (10, 25 or 50 mg/hr) or l‐tryptophan (50, 100 or 250 mg/kg) was given as a bolus intraperitoneal (i.p.) injection 30 min prior to the onset of pancreatitis. CIP and I/R were confirmed by histologic examination and manifested by typical pancreatic edema, by an increase of plasma levels of amylase (by 500% in CIP and by 40% in I/R) and the pro‐inflammatory tumor necrosis factor α (TNFα) (by 500%). Lipid peroxidation products such as malondialdehyde (MDA) and 4‐hydroxynonenal (4‐HNE), were increased several fold in the pancreas CIP and I/R, whereas pancreatic blood flow (PBF) was significantly reduced in these animals. Pretreatment of rats subjected to CIP or to I/R with melatonin (25 or 50 mg/kg i.p.) or l‐tryptophan (100 or 250 mg/kg i.p.) significantly reduced pancreatic edema, plasma levels of amylase and TNFα and diminished pancreatic MDA + 4‐HNE contents, while enhancing PBF, pancreatic integrity and plasma levels of the anti‐inflammatory interleukin 10 (IL‐10). This was accompanied by a marked and dose‐dependent rise of plasma melatonin immunoreactivity. Gene expression of N‐acetyl transferase, an enzyme involved in melatonin biosynthesis, was detected in the pancreas of normal rats and was significantly enhanced in the rats with CIP. We conclude that exogenous melatonin, and that produced from l‐tryptophan, attenuates pancreatic damage induced by CIP or by I/R and this effect may be attributable to the reduction in lipid peroxidation and TNFα release combined with an increase of plasma anti‐inflammatory IL‐10 in rats with acute pancreatitis.
Physiological models to understand exercise fatigue and the adaptations that predict or enhance athletic performance
Authors: Noakes T. D.
Published: March 2003

A popular concept in the exercise sciences holds that fatigue develops during exercise of moderate to high intensity, when the capacity of the cardiorespiratory system to provide oxygen to the exercising muscles falls behind their demand inducing “anaerobic” metabolism. But this cardiovascular/anaerobic model is unsatisfactory because (i) a more rigorous analysis indicates that the first organ to be affected by anaerobiosis during maximal exercise would likely be the heart, not the skeletal muscles. This probability was fully appreciated by the pioneering exercise physiologists, A. V. Hill, A. Bock and D. B. Dill, but has been systematically ignored by modern exercise physiologists; (ii) no study has yet definitely established the presence of either anaerobiosis, hypoxia or ischaemia in skeletal muscle during maximal exercise; (iii) the model is unable to explain why exercise terminates in a variety of conditions including prolonged exercise, exercise in the heat and at altitude, and in those with chronic diseases of the heart and lungs, without any evidence for skeletal muscle anaerobiosis, hypoxia or ischaemia, and before there is full activation of the total skeletal muscle mass, and (iv) cardiovascular and other measures believed to relate to skeletal muscle anaerobiosis, including the maximum oxygen consumption (VO2 max) and the “anaerobic threshold”, are indifferent predictors of exercise capacity in athletes with similar abilities. This review considers four additional models that need to be considered when factors limiting either short duration, maximal or prolonged submaximal exercise are evaluated. These additional models are: (i) the energy supply/energy depletion model; (ii) the muscle power/muscle recruitment model; (iii) the biomechanical model and (iv) the psychological model. By reviewing features of these models, this review provides a broad overview of the physiological, metabolic and biomechanical factors that may limit exercise performance under different exercise conditions. A more complete understanding of fatigue during exercise, and the relevance of the adaptations that develop with training, requires that the potential relevance of each model to fatigue under different conditions of exercise must be considered.*
Walking trials in postmenopausal women: effect of one vs two daily bouts on aerobic fitness
Authors: Asikainen T‐M. , Miilunpalo S. , Oja P. , Rinne M. , Pasanen M. , Vuori I.
Published: March 2003

We compared the effects of one vs two daily bouts of walking on aerobic fitness and body composition in postmenopausal women. One hundred and thirty‐four subjects were randomized into exercise groups or a control group and 130 completed the study. The subjects walked 5 d/week for 15 weeks at 65% of their maximal aerobic power expending 300 kcal (1255 kJ) in exercise in one (Group S1) or two daily sessions (Group S2). VO2max was measured in a direct maximal treadmill test. Body mass index (BMI) was calculated and the percentage of body fat (fat%) estimated using skinfold measurements. The net change in the VO2max was 2.5 mL min/kg (95% CI 1.5, 3.5) (8.7%) in Group S1 and 2.5 mL min/kg (95% CI 1.5, 3.5) (8.8%) in Group S2. The net change in body mass was −1.2 kg (95% CI−1.9, −0.5) in Group S1 and −1.1 kg (95% CI −1.8, −0.4) in Group S2. The net fat% change was −2.1% (95% CI−2.7, −1.4) in Group S1 and −1.7% (95% CI−2.3, −1.0) in Group S2. Exercise improved the maximal aerobic power and body composition equally when walking was performed in one or two daily bouts.
A comparative study of the effects on the skin of a classical bar soap and a syndet cleansing bar in normal use conditions and in the soap chamber test
Authors: Barel A. O. , Lambrecht R. , Clarys P. , Morrison B. M. , Paye M.
Published: March 2003

Background/aims: The skin irritation potential of a body cleansing product is often compared under exaggerated test conditions, although the product is intended to be used at home with repetitive and brief contact with the skin. The aim of this study was to determine how much patch testing is predictive of the clinical, sub‐clinical and subjective cutaneous effects of products used at home by consumers for their normal hygienic cleansing.

Methods: A double‐blind comparative study of the normal use of an alkaline soap bar and a syndet at home during 10 consecutive weeks was performed on two identical groups of 25 healthy female subjects. The eventual skin changes observed at different anatomical skin sites were evaluated by clinical visual examination and by bioengineering measurements before the start of the study and then every 2 weeks. The objective measurements were compared with the subject’s perceptions of dryness, tightness and product irritancy during the testing.

Results: The bioengineering measurements did not show any significant changes on all the anatomical skin sites, except for a small increase in skin pH with the classical soap bar. However, a trend appeared, showing that the alkaline soap bar is perceived by the subjects themselves as more of an irritant than the syndet bar. In the soap chamber test, the bar soap showed a significantly higher irritancy than the syndet bar.

Conclusion: This study showed that cutaneous irritation induced by cleansing products in patch testing is not necessarily predictive of the irritation likely to occur in normal use conditions. Finally, a clear relationship could be demonstrated between the results of the soap chamber test and the consumer perception of both cleansing bars.
Graphic analysis of the relationship between skin colour change and variations in the amounts of melanin and haemoglobin
Authors: Takiwaki H. , Miyaoka Y. , Kohno H. , Arase S.
Published: March 2003

Background/aims The L*a*b* coordinate is the most commonly used colour system to measure skin colour in dermatology and cosmetology. In this system, a* and L* are often used for quantification of the degrees of erythema and pigmentation. The aim of this study was to examine whether a* and L* can be used as specific scales to indicate the amount of haemoglobin and melanin, respectively, in the skin.

Methods The a* and L* values were examined with a reflectance spectrometer in various skin conditions or lesions caused by a change in the amount of either melanin or haemoglobin, i.e. vitiligo, ultraviolet‐induced pigmentation (PG), erythema resulting from slapping (ER), corticosteroid‐induced blanching, erythema due to stasis by arm lowering, and a combination of PG and ER. The differences in values between the test sites and the adjacent normal skin, Δa* and ΔL*, were plotted on the Δa*–ΔL* plane and analysed statistically and geometrically.

Results L* depended substantially not only on melanin but also on haemoglobin, especially if the oxygen saturation level was expected to be low. a* was also influenced by melanin. The results of graphic analysis indicated that a linear transformation of (Δa*, ΔL*) into (ΔHb = 1.68 Δa* + 0.60 ΔL*, ΔMel =−1.06 Δa*–1.44 ΔL*) was suitable for separately estimating the change in the amount of haemoglobin (ΔHb) and in that of melanin (ΔMel).

Conclusion The results of this study may be of value for understanding the relationship between colour coordinates of the skin and the quantities of haemoglobin and melanin, and may be of use when pigmented lesions of the face are monitored by tristimulus colourimetry, as facial skin colour is affected considerably by the rich and easily variable cutaneous blood flow.
Melanoma or pigmented basal cell carcinoma: a clinical‐pathologic correlation with dermoscopy, in vivo confocal scanning laser microscopy, and routine histology
Authors: Charles Carlos A. , Marghoob Ashfaq A. , Busam Klaus J. , Clark‐Loeser Lesley , Halpern Allan C.
Published: March 2003

Background/purpose: New techniques are being explored for improving diagnostic accuracy of pigmented skin lesions. Confocal scanning laser microscopy (CSLM) may represent such a novel technique. The purpose of this report was to demonstrate the potential application of CSLM as an aid in the diagnosis of a pigmented skin lesion that is clinically suspicious for melanoma.

Methods: An irregular pigmented lesion was examined clinically and dermoscopically. The lesion was imaged by CSLM and subsequently excised for histologic examination. Findings from CSLM were correlated with features observed on the dermoscopic and histologic examination.

Results: Confocal scanning laser microscopy (CSLM) allowed for the non‐invasive visualization of the histologic features of superficial pigmented BCC, including buds and “islands” of tumor cells at the dermoepidermal junction and melanin‐laden macrophages. Conventional histology confirmed the diagnosis of pigmented BCC.

Conclusion: Confocal scanning laser microscopy (CSLM) may serve as an aid in the non‐invasive diagnosis of pigmented skin lesions clinically suspicious for melanoma.
Quantitative description of human skin water dynamics by a disposition‐decomposition analysis (DDA) of trans‐epidermal water loss and epidermal capacitance
Authors: Rodrigues Luis Monteiro , Pinto Pedro Contreiras , Pereira Luis Marcelo
Published: March 2003

Background: In vivo water assessment would greatly benefit from a dynamical approach since the evaluation of common related variables such as trans‐epidermal water loss or “capacitance” measurements is always limited to instantaneous data. Mathematical modelling is still an attractive alternative already attempted with bi‐exponential empirical models. A classical two‐compartment interpretation of such models raises a number of questions about the underlying fundamentals, which can hardly be experimentally confirmed. However, in a system analysis sense, skin water dynamics may be approached as an ensemble of many factors, impossible to discretize, but conceptually grouped in terms of feasible properties of the system. The present paper explores the applicability of this strategy to the in vivo water dynamics assessment.

Methods: From the plastic occlusion stress test (POST) skin water balance is assessed by modelling trans‐epidermal water loss (TEWL) and “capacitance” data obtained at skin's surface. With system analysis (disposition‐decomposition analysis) the distribution function, H(t), modelled as a sum of exponential terms, covers only the distribution characteristics of water molecules traversing the skin. This may correspond macroscopically to the experimental data accessed by “corneometry”. Separately, the hyperbolic elimination function Q(TEWL) helps to characterise the dynamic aspects of water influx through the skin.

Discussion and conclusion: In the observable range there seems to be a linear relationship between the net amount of water lost at the surface by evaporation, and the capability of the system to replenish that loss. This may be a specific characteristic of the system related to what may be described as the skin's “intrinsic hydration capacity” (IHC) a new functional parameter only identified by this strategy. These new quantitative tools are expected to find different applicabilities (from the in vivo skin characterisation to efficacy testing) contributing to disclose the dynamical nature of the skin water balance process.
Stirring up Development with the Heterotrimeric Kinesin KIF3
Authors: Hirokawa Nobutaka
Published: March 2003

KIF3 is a heterotrimeric member of the kinesin superfamily of microtubule associated motors. This functionally diverse family of motors is involved in anterograde transport of membrane bound organelles in neurons and melanosomes, mediates transport between the endoplasmic reticulum and the Golgi, and transports protein complexes within cilia and flagella required for their morphogenesis. Interestingly, a mutation of KIF3, which impairs ciliogenesis in nodal cells, prevents the unidirectional leftward flow (nodal flow) of putative morphogens during embryogenesis, thereby altering the development of left–right asymmetry in mammals.
Clathrin Function in Yeast Endocytosis
Authors: Baggett Jennifer J. , Wendland Beverly
Published: March 2003

The process of endocytosis is a complex series of events involving the coordinated activity of many proteins. In animal cells, clathrin plays a vital role in the invagination of the plasma membrane leading to formation of vesicles during endocytosis. The study of endocytosis in yeast cells has been hindered by a debate about the role of clathrin in early internalization steps. This review summarizes the evidence for and against clathrin's involvement in internalization from the yeast plasma membrane.
Studies of Synaptic Vesicle Endocytosis in the NematodeC. elegans
Authors: Harris Todd W. , Schuske Kim , Jorgensen Erik M.
Published: March 2003

After synaptic vesicle exocytosis, synaptic vesicle proteins must be retrieved from the plasma membrane, sorted away from other membrane proteins, and reconstituted into a functional synaptic vesicle. The nematodeCaenorhabditis elegansis an organism well suited for a genetic analysis of this process. In particular, three types of genetic studies have contributed to our understanding of synaptic vesicle endocytosis. First, screens for mutants defective in synaptic vesicle recycling have identified new proteins that function specifically in neurons. Second, RNA interference has been used to quickly confirm the roles of known proteins in endocytosis. Third, gene targeting techniques have elucidated the roles of genes thought to play modulatory or subtle roles in synaptic vesicle recycling. We describe a molecular model for synaptic vesicle recycling and discuss how protein disruption experiments inC. eleganshave contributed to this model.
In Vitro Assays of Vesicular Transport
Authors: Cook Neil R. , Davidson Howard W.
Published: March 2003

Movement of proteins and lipids between the various compartments of eukaryotic cells is fundamental to the maintenance of cellular homeostasis, and an understanding of the molecular mechanisms that govern these processes remains a key goal of cell biological research. This aim has been greatly facilitated by the development of assays that recapitulate specific events in vitro. In the following article we provide an overview of some of the currently used assays that measure the movement of proteins within the exocytic and endocytic pathways, and provide a starting point for those wishing to establish their own systems to study other vesicular transport steps.
Clathrin‐Dependent and Clathrin‐Independent Endocytosis are Differentially Sensitive to Insertion of Poly (Ethylene Glycol)‐Derivatized Cholesterol in the Plasma Membrane
Authors: Baba Takeshi , Rauch Cyril , Xue Mei , Terada Nobuo , Fujii Yasuhisa , Ueda Hideho , Takayama Ichiro , Ohno Shinichi , Farge Emmanuel , Sato Satoshi B.
Published: March 2003

We examined the effect of a cholesterol derivative, poly (ethylene glycol) cholesteryl ether on the structure/function of clathrin‐coated pits and caveolae. Addition of the compound to cultured cells induced progressive smoothening of the surface. Markedly, when the incorporated amount exceeded 10% equivalent of the surface area, fluid pinocytosis, but not endocytosis of transferrin, became inhibited in K562 cells. In A431 cells, both clathrin‐independent fluid phase uptake and the internalization of fluorescent cholera‐toxin B through caveolae were inhibited with concomitant flattening of caveolae. In contrast, clathrin‐mediated internalization of transferrin was not affected until the incorporated poly (ethylene glycol) cholesteryl ether exceeded 20% equivalent of the plasma membrane surface area, at which point opened clathrin‐coated pits accumulated. The cells were ruptured upon further addition of poly (ethylene glycol) cholesteryl ether. We propose that the primary reason for the differential effect of poly (ethylene glycol) cholesteryl ether is that the bulk membrane phase and caveolae are both more elastic than the rigid clathrin‐coated pits. We analyzed the results with the current mechanical model (Rauch and Farge, Biophys J 2000;78:3036–3047) and suggest here that the functional clathrin‐lattice is much stiffer than typical phospholipid bilayers.
Qualitative Highly Divergent Nuclear Export Signals Can Regulate Export by the Competition for Transport Cofactors in Vivo
Authors: Heger Peter , Lohmaier Jens , Schneider Grit , Schweimer Kristian , Stauber Roland H.
Published: March 2003

Nucleo‐cytoplasmic transport of proteins is mediated by nuclear export signals, identified in various proteins executing heterologous biological functions. However, the molecular mechanism underlying the orchestration of export is only poorly understood. Using microinjection of defined recombinant export substrates, we now demonstrate that leucine‐rich nuclear export signals varied dramatically in determining the kinetics of export in vivo. Thus, nuclear export signals could be kinetically classified which correlated with their affinities for CRM1‐containing export complexes in vitro. Strikingly, cotransfection experiments revealed that proteins containing a fast nuclear export signal inhibited export and the biological activity of proteins harboring a slower nuclear export signal in vivo. The affinity for export complexes seems therefore predominantly controlled by the nuclear export signal itself, even in the context of the complete protein in vivo. Overexpression of FG‐rich repeats of nucleoporins affected a medium nuclear export signal containing protein to the same extent as a fast nuclear export signal containing protein, indicating that nucleoporins appear not to contribute significantly to nuclear export signal‐specific export regulation. Our results imply a novel mode for controlling the biological activity of shuttle proteins already by the composition of the nuclear export signal itself.
Trafficking of Yellow‐Fluorescent‐Protein‐Tagged µ1 Subunit of Clathrin Adaptor AP‐1 Complex in Living Cells
Authors: Huang Fangtian , Nesterov Alexandre , Carter Royston E. , Sorkin Alexander
Published: March 2003

Clathrin adaptor protein AP‐1 complex is thought to function in forming clathrin‐coated vesicles at the trans‐Golgi network (TGN) and mediating transport of cargo between the TGN and endosomes. To study trafficking of AP‐1 in living cells, yellow fluorescent protein (YFP) was inserted in the middle of µ1 A subunit of AP‐1. When expressed in a tetracycline‐dependent manner in HeLa cells, YFP‐µ1 was efficiently incorporated into the AP‐1 complex, replacing endogenous µ1 in most of cellular AP‐1. Time‐lapse imaging revealed that YFP‐µ1/AP‐1 departs from TGN as isolated vesicles and spherical structures, or varicosities, associated with fine tubular processes. Typically, several vesicles or varicosities were seen moving sequentially along the same ‘tracks’ from TGN to cell periphery. These data suggest that AP‐1 may function after formation of Golgi transport intermediates in facilitating their intracellular movement. Mutagenesis of YFP‐µ1 determined that the structural requirements for its binding to tyrosine‐containing sequence motifs are similar to those previously defined in µ2 subunit of AP‐2. Moreover, the carboxyl‐terminal half of µ2 could replace the corresponding fragment of µ1 without loss of the ability of the resulting µ1‐YFP‐µ2 chimeric protein to incorporate into AP‐1 and bind tyrosine‐containing motifs. Mutations that abolish binding capacity for tyrosine motifs did not mistarget AP‐1 in the cell, suggesting that AP‐1 interactions with this type of sorting signals are not essential for membrane docking of AP‐1 at the TGN. Altogether, this study demonstrates that YFP‐tagged µ1 protein can serve as a useful tool for visualizing the dynamics of AP‐1 in living cells and for the structure‐function analysis of µ1–cargo interactions.
Ubiquitin‐Independent Entry into the Yeast Recycling Pathway
Authors: Chen Linyi , Davis Nicholas G.
Published: March 2003

The yeast a‐factor receptor (Ste3p) is subject to two mechanistically distinct modes of endocytosis: a constitutive, ligand‐independent pathway links to vacuolar degradation of the receptor, while a ligand‐dependent uptake pathway links primarily to recycling and thus, receptor reutilization. Ste3p ubiquitination triggers its uptake into the constitutive pathway. The present work considers the role of the receptor ubiquitination associated with the Ste3p ligand‐dependent endocytosis mechanism. The doa4Δ mutation which reduces the cellular availability of ubiquitin blocks the Ste3p constitutive uptake. Uptake into the Ste3p ligand‐dependent recycling pathway, however, continues unimpaired. The ubiquitin independence of Ste3p ligand‐dependent uptake was further indicated by analysis of receptor mutants having Lys‐to‐Arg substitutions at all possible ubiquitin acceptor sites. Again, the ligand‐induced internalization was unimpaired. Furthermore, no discernible effect was seen on either recycling or on the slow PEP4‐dependent turnover of the receptor (for receptor internalized via the ligand‐dependent mechanism, trafficking to the vacuole/lysosome is the minor, alternate fate to recycling). However, one striking effect of the Lys‐to‐Arg mutations was noted. Following a prolonged exposure of the cells to the a‐factor ligand, rather than being delivered to the vacuolar lumen, the Lys‐to‐Arg receptor was found to localize instead to the limiting membrane of the vacuole. Thus, while receptor ubiquitination clearly is not required for either the a‐factor‐dependent uptake into recycling pathway or for the recycling itself, it does affect the routing of receptor to the vacuole, likely by affecting the routing through the late endosomal, multivesicular body: ubiquitinated receptor may be selected into the internal, lumenal vesicles, while unmodified receptor may be left to reside at the limiting external membrane.
The Dark Side of Lysosome‐Related Organelles: Specialization of the Endocytic Pathway for Melanosome Biogenesis
Authors: Raposo Graça , Marks Michael S.
Published: March 2003

Melanosomes are lysosome‐related organelles within which melanin pigments are synthesized and stored in melanocytes and retinal pigment epithelial cells. Early ultrastructural studies of pigment cells revealed that melanosomes consist of a complex series of organelles; more recently, these structures have been correlated with cargo constituents. By studying the fate of melanosomal and endosomal cargo in melanocytic cells, the effects of disease‐related mutations on melanosomal morphology, and the genes affected by these mutations, we are beginning to gain novel insights into the biogenesis of these complex organelles and their relationship to the endocytic pathway. These insights demonstrate how specialized cells integrate unique and ubiquitous molecular mechanisms in subverting the endosomal system to generate cell‐type specific structures and their associated functions. Further dissection of the melanosomal system will likely shed light not only on the biogenesis of lysosome‐related organelles but also on general aspects of vesicular transport in the endosomal system.