The distribution and ecology of Malassezia furfur and cutaneous bacteria on human skin

The prevalence and abundance of Malassezia furfur on clinically normal skin at 20 sites has been determined. All of the 16 subjects studied (young adults) had high counts on the upper trunk and on at least one site on the head. Counts obtained from the lower trunk and upper thighs of male subjects were considerably higher than those from female volunteers. Organisms isolated, grouped according to their colony morphologies, had distributions consistent with those noted for ' Pityrosporum ovale 'and ' P. orbiculare 'in previous studies. Mean M. furfur counts were compared with aerobic and anaerobic bacterial counts performed at the same sites. Propionibacteria and M. furfur distributions were similar but not identical. Some factors which might limit the range of M. furfur are discussed.     

Characterization of markedly lipid-dependent Malassezia pachydermatis isolates from healthy dogs

When 244 Malassezia colonies which had been isolated from a colony of Beagle dogs using modified Dixon's agar were sub-cultured on Sabouraud's dextrose agar to determine their lipid dependence, 30 showed poor growth resembling M. furfur , whereas the remainder were typical of M. pachydermatis . Eight of the 10 poor growing isolates selected for further study formed colonies typical of M. pachydermatis after five passages on Sabouraud's dextrose agar at 4 d intervals and two continued to show poor growth. Nine isolates had enzyme profiles identical to those of typical M. pachydermatis isolates, and one resembled M. furfur . However, seven of the poor growing isolates which were karyotyped had patterns typical of M. pachydermatis. Poor growing isolates and their non-lipid-dependent 'revertants'had identical restriction fragment length polymorphism patterns and poly(GT) hybridization profiles. These observations show that some M. pachydermatis isolates grow poorly when sub-cultured onto Sabouraud's dextrose agar and may be incorrectly identified as M. furfur if further studies are not performed.     

Humoral immune response to Malassezia furfur in patients with pityriasis versicolor and seborrheic dermatitis

Humoral immune responses against exoantigen components of oval, elliptic and round yeast forms of Malassezia furfur were analysed by ELISA and Western blotting assays, using sera from patients with pityriasis versicolor (PV), seborrheic dermatitis (SD) and healthy adults (HA), as control. Sera from patients with SD showed IgG anti-oval M. furfur titers ranging from 1/400 to 1/6400 showing geometric mean (GM) of 1/1472, higher than those obtained with sera from patients with PV (1/200 to 1/6400, GM = 1/1239). Both patient groups showed mean titres statistically superior (p < 0.05) than those obtained from HA (GM = 1/229). Similar data were also obtained with the elliptic and round antigens. However, the anti-oval IgG mean titers from patients' sera were much higher than those obtained with elliptic or round antigenic components (p < 0.05). Anti-M. furfur IgM titers obtained from patient's sera with PV against all three exoantigens were statistically superior (p < 0.05) than HA group. Patients with SD showed IgM titers statistically superior (p < 0.05) only to oval yeasts of M. furfur. The IgA mean titers from patients' groups against the different morphological antigens were shown be slightly higher than those HA group. By Western blot, using rabbit anti-sera, the different antigenic components of M. furfur showed a close relationship mainly between oval and elliptic yeast cells antigens. The 70 kDa component of the M. furfur exoantigen of oval morphology was recognized by 84% of the PV patients' sera. On the other hand, SD patients' sera recognized 3 principal components of 70 kDa (100%), 65 kDa (67%) and 84 kDa (53%). These components may be considered immunological markers for PV and SD. Twenty-five percent of HA sera recognized the components of 65, 70 and 94 kDa. This investigation shows that M. furfur antigens can sensitize the host, mainly the oval yeast form of M. furfur with a very important specific IgG response in patients with SD and PV. This revised version was published online in June 2006 with corrections to the Cover Date.     

Decreased susceptibility of Malassezia furfur to UV light by synthesis of tryptophane derivatives

Recently, tryptophane (Trp)-dependent synthesis of pigments and fluorochromes in Malassezia furfur was described. The possible significance of this metabolic pathway for the microorganism remains to be explored. Since the upper parts of the human epidermis are a natural habitat of M. furfur, increased exposure to UV light may be hazardous. Five reference strains and one wild type strain of M. furfur were grown on m-Dixon agar, in which the nitrogen source peptone had been substituted either by pigment-inducing tryptophane or arginine. The yeast cells thus obtained were harvested after 6 days, washed with physiological saline and inoculated on to the modified Dixon medium. Immediately after inoculation, the yeast cells were irradiated with UVA (100, 150 and 200 Jcm^-2, single dose) or UVB (100, 500, 1000, 1500, 2000 mJcm^-2, single dose; 500, 1500, 2500 mJcm^-2cumulative dose). Irrespective of the primary nitrogen source (Trp or Arg), unexposed controls showed nearly identical cell yield after 5 days. In the case of irradiation, however, growth reduction of cells cultured on Trp was lesser than that of cells fed with arginine. High significance (p<0.0001) was found especially with the upper UVA and UVB doses. Differences were also found among the individual test strains, the wild strain being most sensitive. One strain (CBS 6094) failed to produce pigment on Trp medium, and there were no differences in the growth behavior of subcultures of this strain fed with either arginine or tryptophane under irradiation. In conclusion, synthesis of pigments and fluorochromes by M. furfur implies the generation of potent UV filters in the UVA and UVB spectrum.     

Allergenic evaluation of Malassezia furfur crude extracts

Crude extracts of the lipophilic yeast Malassezia furfur were obtained from 2, 6, 10 and 28 day old cultures. The in vitro cultivation periods corresponded, respectively, to the lag phase, middle of the log phase, end of log phase and the decline phase of the growth curve, which was based on viable cell counts obtained with a fluorescent viability test. Biochemical analyses showed that the protein and carbohydrate contents were greater in day 10 extracts. Seventy patients with different allergic manifestations and 30 healthy volunteers were skin prick tested using the extracts. Of these, thirteen (18.57%) patients gave positive responses. SDS PAGE gradient electrophoretic profiles of the preparations indicated that the 28 day extracts contained the greatest number of protein bands with molecular weights ranging mostly between 30 and 94 kDa. Immunoblots incubated with individual patient sera showed that four IgE binding M. furfur allergens of approximately 88, 61, 52 and 39 kDa were present in the 28 day extracts. The components identified could be used for detecting IgE mediated responses to M. furfur among individuals affected with different allergic conditions.     

The genitals and gluteal skin are represented lateral to the foot in anterior parietal somatosensory cortex of macaques

Detailed electrophysiological maps of the representations of trunk and adjacent body parts in area 3b and area 1 of somatosensory cortex were obtained in three macaque monkeys (Macaca mulatta and Macaca radiata) of either sex. A total of 211 microelectrode penetrations 250-300 microm apart resulted in 1,190 recording sites. During penetrations deep into the posterior bank of the central sulcus, recordings were made every 300 microm to depths of 6-7 mm until sites unresponsive to somatic stimuli were reached. Cortex was later cut parasagittally and sections were stained for cytochrome oxidase (CO) or Nissl substance. Contrary to expectations from earlier reports, the genitalia were represented lateral to the representations of the foot in cortex along the area 3b/1 border. The gluteal skin including the gluteal pads and the base of the tail were also represented in this section of cortex. Only a small region of cortex was devoted to the genitalia, and neurons in this cortex had receptive fields that were large and typically included skin of the inner thigh and belly. The lower, middle and upper trunk were represented more laterally, followed by the neck, upper head and arm. The receptive fields on the trunk were roughly the same size as those for the middle and lower trunk and slightly smaller on the upper trunk.     

The genitals and gluteal skin are represented lateral to the foot in anterior parietal somatosensory cortex of macaques

Detailed electrophysiological maps of the representations of trunk and adjacent body parts in area 3b and area 1 of somatosensory cortex were obtained in three macaque monkeys ( Macaca mulatta and Macaca radiata ) of either sex. A total of 211 microelectrode penetrations 250-300 &#119 m apart resulted in 1,190 recording sites. During penetrations deep into the posterior bank of the central sulcus, recordings were made every 300 &#119 m to depths of 6-7 mm until sites unresponsive to somatic stimuli were reached. Cortex was later cut parasagittally and sections were stained for cytochrome oxidase (CO) or Nissl substance. Contrary to expectations from earlier reports, the genitalia were represented lateral to the representations of the foot in cortex along the area 3b/1 border. The gluteal skin including the gluteal pads and the base of the tail were also represented in this section of cortex. Only a small region of cortex was devoted to the genitalia, and neurons in this cortex had receptive fields that were large and typically included skin of the inner thigh and belly. The lower, middle and upper trunk were represented more laterally, followed by the neck, upper head and arm. The receptive fields on the trunk were roughly the same size as those for the middle and lower trunk and slightly smaller on the upper trunk.     

In vitro anti-Malassezia activity of xanthorrhizol isolated from Curcuma xanthorrhiza Roxb

AIMS: This study aimed at investigating the anti-Malassezia activity of xanthorrhizol (XTZ) isolated from Curcuma xanthorrhiza Roxb. against Malassezia furfur ATCC 14521 and Malassezia pachydermatis ATCC 14522. METHODS AND RESULTS: The in vitro susceptibility tests for XTZ were carried out in terms of minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC), using broth microdilution method with endpoint after 48 h. Time-kill curves were determined at concentrations ranging from 0 to 25 microg ml(-1). The MIC values of XTZ against M. furfur and M. pachydermatis were 1.25 and 0.25 mug ml(-1), respectively. The MFC of XTZ was 5 microg ml(-1) for M. furfur and 2.5 microg ml(-1) for M. pachydermatis. Time-kill curves demonstrated that treatment with 25 microg ml(-1) of XTZ for 5 h was able to kill 100% of M. furfur, while 20 microg ml(-1) of XTZ for 15 min killed M. pachydermatis completely. CONCLUSION: XTZ shows potential as an anti-Malassezia agent for inhibiting the growth of M. furfur ATCC 14521 and M. pachydermatis ATCC 14522 in vitro. SIGNIFICANCE AND IMPACT OF THE STUDY: XTZ may be a useful alternative for treating Malassezia-associated diseases.     

The influence of newly synthesised fenporpimorph derivatives on some pathogen yeasts

The effect of minimum inhibitory concentrations (MICs) of six novel fenpropimorph derivatives on lipid and sterol composition of Candida albicans, Cryptococcus neoformans, Malassezia pachydermatis and Malassezia furfur was investigated. The MICs for the most effective derivatives were found in the range from 3.7 to 56.7 microM and were 2-3 times lower compared to the commercial fungicide bifonazol. The more efficient fenpropimorph derivatives were the piperidine derivative for C. albicans and the allylamine derivative for Cr. neoformans, M. pachydermatis and M. furfur. The inhibitor in the growth medium reduced the unsaturation index of the total lipid content in M. furfur and C. albicans.     

Two-dimensional electrophoresis of Malassezia allergens for atopic dermatitis and isolation of Mal f 4 homologs with mitochondrial malate dehydrogenase.

The yeast Malassezia furfur is a natural inhabitant of the human skin microflora that induces an allergic reaction in atopic dermatitis. To identify allergens of M. furfur, we separated a crude preparation of M. furfur antigens as discrete spots by 2-D PAGE and detected IgE-binding proteins using sera of atopic dermatitis patients. We identified the known allergens, Mal f 2 and Mal f 3, and determined N-terminal amino acid sequences of six new IgE-binding proteins including Mal f 4. The cDNA and genomic DNA encoding Mal f 4 were cloned and sequenced. The gene was mitochondrial malate dehydrogenase and encoded Mal f 4 composed of 315 amino acids and a signal sequence of 27 amino acids. We purified Mal f 4, which had a molecular mass of 35 kDa from a membrane fraction of a lysate of cultured cells. Thirty of 36 M. furfur-allergic atopic dermatitis patients (83.3%) had elevated serum levels of IgE to purified Mal f 4, indicating that Mal f 4 is a major allergen. There was a significant correlation of the Phadebas RAST unit values of Mal f 4 and the crude antigen, but not between Mal f 4 and the known allergen Mal f 2.     

A new yeast, Malassezia yamatoensis, isolated from a patient with seborrheic dermatitis, and its distribution in patients and healthy subjects

Over the last few years, new Malassezia species have been found regularly in Japanese subjects. We isolated another new Malassezia species from a Japanese patient with seborrheic dermatitis (SD), and named it M. yamatoensis. In its physiological characteristics and the utilization of Tween by M. yamatoensis is similar to that of M. furfur and M. dermatis. It is distinguished by its growth temperature. To examine the distribution of the microorganism in the skin of patients with SD and atopic dermatitis (AD), and healthy subjects, we applied transparent dressings to the skin, and detected M. yamatoensis DNA using a non-culture-based method that consisted of nested PCR with specific primers. M. yamatoensis DNA was detected from 3 of 31 SD patients (9.7%), 5 of 36 AD patients (13.9%), and 1 of 22 healthy subjects (4.6%). Therefore, M. yamatoensis is a rare member of the cutaneous microflora.     

糠秕马拉色菌酵母态和菌丝态蛋白差异表达的研究

目的通过双向电泳及串联质谱技术鉴定糠秕马拉色菌酵母态及菌丝态差异蛋白,在蛋白水平探讨两态转化机制及致病机理。方法分别诱导糠秕马拉色菌标准株酵母态和菌丝态菌体,利用玻璃珠研磨和超声波破碎细胞壁,三氯乙酸/丙酮沉淀获取总蛋白。双向电泳分离蛋白,PDQuest软件比对找出差异蛋白点。电喷雾串联质谱对差异点进行肽段测序,用Mascot和NCBI的Blast软件经蛋白质数据库鉴定蛋白质。结果经双向电泳分离的糠秕马拉色菌酵母态、菌丝态蛋白各有800多个蛋白点、64个蛋白点表达量有3倍以上差异,其中11个为酵母态特有,9个菌丝态特有。在选取的40个差异点中,成功鉴定出22个点,共16个蛋白。经Mascot和Blast软件检索,有明确功能的蛋白中,肌动蛋白、丝切蛋白等9个蛋白在菌丝态上调,谷胱甘肽转移酶、细胞支架信号蛋白等5个蛋白下调。结论鉴定出16个蛋白分别与细胞代谢、运动、氧化应激等功能相关,为了解糠秕马拉色菌表型转换机制和致病机理提供重要信息。     

糠秕马拉色菌药敏试验新方法的探讨

目的 建立一种新的糠秕马拉色菌药敏试验方法.方法 在ATBF2半固体培养基中添加不同种类和含量的脂质,用ATB Fungus 3药敏板条对ATCC14521和临床分离的糠秕马拉色菌进行了MIC测试.结果 孵育时间为72 h时对照孔中糠秕马拉色菌生长充分,吐温40浓度为1％时糠秕马拉色菌生长充分,且对药敏结果的影响最小.脂质的种类和含量对实验结果有影响.结论 用改良ATB Fungus 3药敏试验方法对糠秕马拉色菌进行抗真菌药敏试验,方法操作简便、结果易观察、试验结果重复性好.临床分离菌株与糠秕马拉色菌ATCC14521在ATB Fungus 3对照孔中的生长状况相同,结果易于判断.     

A quantile count model of water depth constraints on Cape Sable seaside sparrows

1. A quantile regression model for counts of breeding Cape Sable seaside sparrows Ammodramus maritimus mirabilis (L.) as a function of water depth and previous year abundance was developed based on extensive surveys, 1992-2005, in the Florida Everglades. The quantile count model extends linear quantile regression methods to discrete response variables, providing a flexible alternative to discrete parametric distributional models, e.g. Poisson, negative binomial and their zero-inflated counterparts. 2. Estimates from our multiplicative model demonstrated that negative effects of increasing water depth in breeding habitat on sparrow numbers were dependent on recent occupation history. Upper 10th percentiles of counts (one to three sparrows) decreased with increasing water depth from 0 to 30 cm when sites were not occupied in previous years. However, upper 40th percentiles of counts (one to six sparrows) decreased with increasing water depth for sites occupied in previous years. 3. Greatest decreases (-50% to -83%) in upper quantiles of sparrow counts occurred as water depths increased from 0 to 15 cm when previous year counts were 1, but a small proportion of sites (5-10%) held at least one sparrow even as water depths increased to 20 or 30 cm. 4. A zero-inflated Poisson regression model provided estimates of conditional means that also decreased with increasing water depth but rates of change were lower and decreased with increasing previous year counts compared to the quantile count model. Quantiles computed for the zero-inflated Poisson model enhanced interpretation of this model but had greater lack-of-fit for water depths > 0 cm and previous year counts 1, conditions where the negative effect of water depths were readily apparent and fitted better with the quantile count model.     

Detecting Body Fat–A Weighty Problem BMI versus Subcutaneous Fat Patterns in Athletes and Non-Athletes

We aimed to describe the relationship between BMI and the subcutaneous adipose tissue topography within young athletes and non-athletic controls, to comparatively evaluate the diagnostic powers of subcutaneous adipose tissue thicknesses at different body sites, furthermore to explore appropriate cut-offs to discriminate between athletes and controls. Measurements were determined in 64 males and 42 females, who were subsequently separated into two even groups (athletes and non-athletes). The optical device LIPOMETER was applied at standardised body sites to measure the thickness of subcutaneous adipose tissue layers. To calculate the power of the different body sites and the BMI to discriminate between athletes and non-athletes, receiver operating characteristic curve analysis was performed. In men, the neck (optimal cut-off value 2.3 mm) and trunk (optimal cut-off value 15.5 mm) provided the strongest discrimination power: with 90.6% (58 of 64) of the subjects being correctly classified into athletes or non-athletes. Discrimination power of the BMI values was 64.1% (41 of 64 were correctly classified). In women, the upper back (optimal cut-off value 3.3 mm) and arms (optimal cut-off value 15.9 mm) provided the strongest discrimination power with 88.1% (37 of 42 being correctly classified). When using BMI to discriminate between athletes and non-athletes only 52.4% (22 of 42) were correctly classified. These results suggest that compared to BMI levels, subcutaneous fat patterns are a more accurate way of discriminating between athletes and non-athletes. In particular the neck and the trunk compartment in men and the upper back and arms compartment in women, were the best sites to discriminate between young athletes and non-athletes on the basis of their fat patterns.     

Shivering onset, metabolic response, and convective heat transfer during cold air exposure

The onset and intensity of shivering of various muscles during cold air exposure are quantified and related to increases in metabolic rate and convective heat loss. Thirteen male subjects resting in a supine position and wearing only shorts were exposed to 10 degrees C air (42% relative humidity and less than 0.4 m/s airflow) for 2 h. Measurements included surface electromyogram recordings at six muscle sites representing the trunk and limb regions of one side of the body, temperatures and heat fluxes at the same contralateral sites, and metabolic rate. The subjects were grouped according to lean (LEAN, n = 6) and average body fat (NORM, n = 7) content. While the rectal temperatures fluctuated slightly but not significantly during exposure, the skin temperature decreased greatly, more at the limb sites than at the trunk sites. Muscles of the trunk region began to shiver sooner and at a higher intensity than those of the limbs. The intensity of shivering and its increase over time of exposure were consistent with the increase in the convective heat transfer coefficient calculated from skin temperatures and heat fluxes. Both the onset of shivering and the magnitude of the increase in metabolic rate due to shivering were higher for the LEAN group than for the NORM group. A regression analysis indicates that, for a given decrease in mean skin temperature, the increase in metabolic rate due to shivering is attenuated by the square root of percent body fat. Thus the LEAN group shivered at higher intensity, resulting in higher increases in metabolic heat production and convective heat loss during cold air exposure than did the NORM group.     

Ecological and biogeographical effects of forest disturbance on tropical butterflies of Sumba, Indonesia

ABSTRACT. Butterfly assemblages within lowland monsoon forest were compared at four sites on Sumba, Indonesia that differed in terms of protection and exhibited associated differences in levels of human disturbance. A numerical method employing principal components analysis was devised for describing forest structure at each site. The first principal component (PRIN1) grouped attributes tending towards dense forest with closely-spaced trees, a closed canopy and a poorly developed field layer, with trees that tended to be large with the point of inversion in the upper half of the trunk. The highest values for PRIN1 were recorded within protected forest, and PRIN1 values were considered to be a useful index of forest disturbance at each site. Species diversity of butterflies was highest in unprotected secondary forest, but was not affected by lower levels of disturbance. Those species occurring at highest density in secondary forest generally had wide geographical distributions, whereas those species occurring at highest density in undisturbed primary forest had restricted ranges of distribution, in most cases with a separate subspecies on Sumba. Overall, an index of biogeographical distinctiveness decreased with increasing disturbance, and this supports the hypothesis that the most characteristic species of undisturbed climax forest have the smallest geographical ranges of distribution. Species abundance data for butterflies fitted a log-normal distribution at all but the most disturbed site. These results indicate that the pattern of proportional abundance of tropical butterfly species may be used as an ‘instantaneous’ indicator of forest disturbance, and that changes in the structure of tropical forests in S.E. Asia resulting from human disturbance, even within partially-protected forest, may result in the presence of butterfly assemblages of higher species diversity but of lower biogeographical distinctiveness, and therefore of lower value in terms of the conservation of global biodiversity.     

Are adult physiques geometrically similar? The dangers of allometric scaling using body mass power laws

Human physique classification by somatotype assumes that adult humans are geometric similar to each other. However, this assumption has yet to be adequately tested in athletic and nonexercising human populations. In this study, we assessed this assumption by comparing the mass exponents associated with girth measurements taken at 13 different sites throughout the body in 478 subjects (279 athletic subjects, and 199 nonexercising controls). Corrected girths which account for subcutaneous adipose tissue at the upper arm, thigh, and calf sites, and which simulate muscle circumference, were also calculated. If subjects are geometrically similar to each other, girth exponents should be approximately proportional to M(1/3), where M is the subjects' body mass. This study confirms that human adult physiques are not geometrically similar to each other. In both athletic subjects and nonexercising controls, body circumferences/limb girths develop at a greater rate than that anticipated by geometric similarity in fleshy sites containing both muscle and fat (upper arms and legs), and less than anticipated in bony sites (head, wrists, and ankles). Interestingly, head girths appear to remain almost constant, irrespective of subjects' body size/mass. The results also suggest that thigh muscle girths of athletes and controls increase at a greater rate than that predicted by geometric similarity, proportional to body mass (M(0.439) and M(0.377), respectively). These systematic deviations from geometric similarity have serious implications for the allometric scaling of variables such as energy expenditure, oxygen uptake, anaerobic power, and thermodynamic or anthropometric studies involving individuals of differing size.     

The tryptophan aminotransferase Tam1 catalyses the single biosynthetic step for tryptophan-dependent pigment synthesis in Ustilago maydis

Tryptophan is a precursor for many biologically active secondary metabolites. We have investigated the origin of indole pigments first described in the pityriasis versicolor-associated fungus Malassezia furfur . Some of the identified indole pigments have properties potentially explaining characteristics of the disease. As M. furfur is not amenable to genetic manipulation, we used Ustilago maydis to investigate the pathway leading to pigment production from tryptophan. We show by high-performance liquid chromatography, mass spectrometry and nuclear magnetic resonance analysis that the compounds produced by U. maydis include those putatively involved in the etiology of pityriasis versicolor. Using a reverse genetics approach, we demonstrate that the tryptophan aminotransferase Tam1 catalyses pigment biosynthesis by conversion of tryptophan into indolepyruvate. A forward genetics approach led to the identification of mutants incapable of producing the pigments. These mutants were affected in the sir1 gene, presumably encoding a sulphite reductase. In vitro experiments with purified Tam1 showed that 2-oxo 4-methylthio butanoate serves as a substrate linking tryptophan deamination to sulphur metabolism. We provide the first direct evidence that these indole pigments form spontaneously from indolepyruvate and tryptophan without any enzymatic activity. This suggests that compounds with a proposed function in M. furfur -associated disease consist of indolepyruvate-derived spontaneously generated metabolic by-products.