Spontaneous differentiation of germ cells from human embryonic stem cells in vitro

Little is known of molecular requirements for specification of human germ cells. However, it is likely that they are specified through the action of sequentially expressed genes just as in model organisms. We sought to determine whether human embryonic stem (ES) cell lines, like those of mice, might be capable of forming germ cells in vitro. We compared transcriptional profiles of three pluripotent human ES cells to those of isolated inner cell mass (ICM) cells. We found that ICM cells expressed NANOS1, STELLAR and OCT4, whereas undifferentiated human ES cells expressed these genes along with the germ cell-specific gene, DAZL. Upon ES cell differentiation into embryoid bodies (EBs), we observed a shift in expression from RNA and protein markers of immature germ cells to those indicative of mature germ cells, including expression of VASA, BOL, SCP1, SCP3, GDF9 and TEKT1. Although ability to test the function of these putative VASA positive germ cells is limited, these results demonstrate that differentiation of human ES cells into EBs in vitro results in formation of cells that express markers specific to gonocytes.

Sex attractant pheromone of the house fly: isolation, identification and synthesis

A sex pheromone isolated from the cuticle and feces of the female house fly attracts the male fly; it has been identified as (Z)-9-tricosene. Chemical and biological comparisons of the natural and synthesized compounds show that they are identical.

Efficient method for the proteomic analysis of fixed and embedded tissues

Formalin-fixed and paraffin-embedded (FFPE) tissues present a particular challenge for proteomic analysis. Yet, most of the archived tissues in hospitals and tissue banks worldwide are only available in this form. We have developed conditions for removal of the embedding medium and protein digestion, such that informative tryptic peptides are released from fixed proteins which are suitable for analysis by liquid chromatography-mass spectrometry (LC-MS). We demonstrate that the peptide identifications made by this approach compare favorably to those made from matched fresh frozen tissue. Moreover, we demonstrate that a high level of sequence coverage can be observed for proteins of interest.

Dioxin-like activities, halogenated flame retardants, organophosphate esters and chlorinated paraffins in dust from Australia, the United Kingdom, Canada, Sweden and China

The concentrations of organic flame retardants (FRs) and dioxin-like activities in dust collected from five countries were investigated. The correlations between the concentrations of the different groups of FRs and dioxin-like activities were examined. Chlorinated paraffins (CPs, C₉ to C₃₁) were found in the highest concentration (median ∑CP 700 μg/g, range 280-4750 μg/g), followed by organophosphate esters (median ∑₁₃OPEs 56 μg/g, range 21-110 μg/g), halogenated flame retardants (median ∑₁₇HFRs 3.3 μg/g, range 0.87-14 μg/g) and polybrominated diphenyl ethers (median ∑₁₇PBDEs 2.8 μg/g, range 0.46-11 μg/g). There were no significant differences in concentrations of the FRs among the countries but differences in PBDE and CP congener profiles were found. BDE209 predominated in dust from Australia, the UK, Sweden and China, ranging from 50 to 70% of total PBDEs. The lowest percentage of BDE209 was found in the dust from Canada, representing only 20% of total PBDEs. For CPs in dust from Sweden, the long-chain CPs (especially C₁₈ congeners) predominated, while for other countries, medium-chain CPs (especially C₁₄ congeners) predominated. The dioxin-activities of the dusts ranged from 58 to 590 pg CALUX-TEQ/g, and had a median of 200 pg CALUX-TEQ/g. There were significant positive correlations between concentrations of PBDEs and CPs with dioxin-like activities. The dioxin-like activity may be due to the presence of polychlorinated or polybrominated dioxin/furans (PBDD/DFs) or polychlorinated naphthalenes (PCNs) in the dust. The PBDD/DFs are known impurities and degradation product of the penta-BDE mixture, and PCNs are known impurities of CPs which exhibit dioxin-like activities.

Immunolabeling of carbonic anhydrase isoenzyme C and glial fibrillary acidic protein in paraffin-embedded tissue sections of human brain and retina

The specificities of carbonic anhydrase isoenzyme C (CA C) and glial fibrillary acidic (GFA) protein as immunocytochemical markers for different glial cell populations in human brain and retina were studied using indirect immunofluorescence and peroxidase-antiperoxidase complex methods. With antibodies against CA C, only those cerebral cells that were morphologically oligodendrocytes and Müller cells of the retina showed positive immunostaining reaction, whereas antibodies against GFA protein selectively labeled cerebral astrocytes and a part of the glial cells and fibers in the inner layers of the retina. In double labeling, when both glial cell markers were successively localized in the same cerebral tissue sections, GFA protein immunofluorescence was never found in the immunoperoxidase-stained CA C-positive cells, which further supports the oligodendrocyte-specificity of CA C in human brain.

Stimulated and unstimulated saliva samples have significantly different bacterial profiles

Epidemiological studies use saliva on a regular basis as a non-invasive and easy-to-take sample, which is assumed to be a microbial representative of the oral cavity ecosystem. However, comparative studies between different kinds of saliva samples normally used in microbial studies are scarce. The aim of the current study was to compare oral microbiota composition between two different saliva samples collected simultaneously: non-stimulated saliva with paper points and stimulated saliva collected after chewing paraffin gum. DNA was extracted from saliva samples of ten individuals, then analyzed by 16S rRNA pyrosequencing to describe bacterial diversity. The results demonstrate significant differences between the microbiota of these two kinds of saliva. Stimulated saliva was found to contain an estimated number of species over three times higher than unstimulated saliva. In addition, bacterial composition at the class and genus level was radically different between both types of samples. When compared to other oral niches, both types of saliva showed some similarity to tongue and buccal mucosa, but they do not correlate at all with the bacterial composition described in supra- or sub-gingival dental plaque, questioning their use in etiological and epidemiological studies of oral diseases of microbial origin.

Emission wavelength-dependent decay of the 9-anthroyloxy-fatty acid membrane probes

Using the phase-modulation technique, we have measured the fluorescence decay of 2- and 12-(9-anthroyloxy)-stearic acid (2- and 12-AS) and 16-(9-anthroyloxy)-palmitic acid (16-AP) bound to egg phosphatidylcholine vesicles or dissolved in nonpolar solvents. Heterogeneity analysis demonstrates that the decay is generally not monoexponential and exhibits large component variations across it emission spectrum. The mean decay time increases (and in parallel, the steady-state polarization decreases) monotonically with increasing wavelength from values at the blue end. The decay at the red side of the emission spectrum contains an exponential term with a negative amplitude, indicating that emission occurs from intermediates created in the excited-state. This behavior is interpreted as arising from intramolecular fluorophore relaxation occurring on the time scale of the fluorescence lifetime. We believe this to be the first study of wavelength-dependent fluorescent emission which is dominated by an intramolecular relaxation process. Although the three probes exhibit qualitatively similar effects, the emission band variations are greatest for 2-AS and smallest for 16-AP. The differences among the probes are not entirely due to environmental factors as demonstrated, for example, by the emission polarization differences observed in the isotropic solvent paraffin oil. In summary, while these findings point out some of the complexities in the 9-anthroyloxy-fatty acids as membrane probes, they also indicate how these complexities might be used as a sensitive measure of lipid-probe interaction.

In situ hybridization to mRNA of Arabidopsis tissue sections

In situ hybridization detection of mRNA is an essential tool for understanding regulation of gene expression in cells and tissues of different organisms. Over the years, numerous in situ protocols have been developed ranging from whole-mount techniques that allow fast transcript localization in intact organs to high-resolution methods based on the electron microscopic detection of mRNAs at the subcellular level. Here, we present a detailed protocol for the detection of mRNAs in plant tissues using radiolabeled single-stranded RNA probes. Hybridizations are carried out on tissue sections of paraffin- and plastic-embedded plant tissues. Although this in situ protocol is appropriate for plant tissues in general, it has been optimized for Arabidopsis thaliana. Variations on the procedure, required to obtain optimal results with different Arabidopsis tissues, are described.

An explanation for the 'placebo' effect of bland ointment bases

Bland topical applications, containing no pharmacologically active ingredients, were found to have an antimitotic effect on the epidermis of the stripped dorsal skin of hairless mice. White soft paraffin, cetomacrogol cream A (B.P.), starch paste, and emulsifying ointment (B.P.) were applied for 24 h periods under occlusive dressing to the backs of mice. The antimitotic effect was present at the time of removal of the dressings and up to 72 h after removal. White soft paraffin had the maximal antimitotic activity and epidermis of mice treated with it showed only 23% of the number of mitoses of control animals having no such treatment. Emulsifying ointment had the least activity and in some circumstances actually seemed stimulatory to mitotic activity.

Reduction of skin water loss in the newborn. I. Effect of applying topical agents

The waterproofing effect of a number of creams, oils, and greases was examined by measuring water loss from adult skin before and after topical application. Creams had a high water content and were ineffective, oils produced a modest fall in water loss, but paraffin in grease form had a pronounced, sustained waterproofing effect. A paraffin mixture (80% soft, 20% hard paraffin (BP) was then applied to the skin of 3 preterm babies nursed naked in incubators. Overall skin water loss fell by 40 to 60% after application and was still lower than pretreatment levels 6 hours later. The topical application of paraffin offers a new approach to reduction of the high evaporative water and heat losses of preterm babies.

Salivary stimulus and swallowing reflex in man

The importance of receptor stimulation by saliva for the elicitation of the swallowing reflex in man was investigated by testing the capacity for repeated dry swallowing at maximum frequency in two controlled series: one with stimulated and one with inhibited secretion of saliva. The swallowing response was recorded manometrically. A positive correlation was found between the secretion of saliva and the capacity was found between the secretion of saliva and the capacity for repeated dry swallowing. It was concluded that the swallowing reflex in man is dependent on an adequate stimulus. The importance of an intact saliva secretion specially in cases with swallowing dysfunction is pointed out.

Regional differences in rat large intestinal crypt function in relation to dehydrating capacity in vivo

1. Rat descending colon absorbed fluid against a large hydraulic resistance, imposed by 10 % agarose (w/v) gel plugs inserted in the lumen, by raising the tonicity of the absorbate from the gel to 880 +/- 54 mosmol kg-1; the tonicity of the absorbate from 2.5 % gels was 352 +/- 38 mosmol kg-1. The hypertonic absorbate generated an osmotic pressure which created a fluid tension in the crypt lumen. This was monitored as a suction tension in colonic luminal gels of 45.3 +/- 3 cmH2O with 2.5 % gels and 725 +/- 145 cmH2O with 10 % gels. The caecum was unable to absorb fluid against a significant hydraulic resistance. 2. Fluorescein isothiocyanate-labelled dextran (FITC dextran; molecular mass 10000 Da) accumulated within descending colonic crypt lumens by concentration polarization. Maximal accumulation at a depth of 20-40 micrometer below the mucosal surface was 5.68 +/- 0.2-fold above control levels. Caecal crypts accumulated dextran to a maximum of 1.8 +/- 0.17-fold above control levels. 3. The relationship between crypt luminal tension and suction tension of the distal colon was also demonstrated using paraffin, which occluded the crypt lumens with microscopic droplets and completely inhibited fluid absorption from high resistance luminal gels. 4. Reduction in dietary Na+ intake raised plasma aldosterone and the capacity of the distal colon to dehydrate against a high luminal hydraulic resistance. The caecum did not respond in this way to varied Na+ intake.

RT-PCR analysis of RNA extracted from Bouin-fixed and paraffin-embedded lymphoid tissues

In the present study, we have investigated whether RNA can be efficiently isolated from Bouin-fixed or formalin-fixed, paraffin-embedded lymphoid tissue specimens. To this aim, we applied a new and simple method that includes the combination of proteinase K digestion and column purification. By this method, we demonstrated that the amplification of long fragments could be accomplished after a pre-heating step before cDNA synthesis associated with the use of enzymes that work at high temperature. By means of PCR using different primers for two examined genes (glyceraldehyde-3-phosphate dehydrogenase [GAPDH]- and CD40), we amplified segments of cDNA obtained by reverse transcription of the isolated RNA extracted from Bouin-fixed or formalin-fixed paraffin-embedded tissues. Amplified fragments of the expected sizes were obtained for both genes tested indicating that this method is suitable for the isolation of high-quality RNA. To explore the possibility for giving accurate real time quantitative RT-PCR results, cDNA obtained from matched frozen, Bouin-fixed and formalin-fixed neoplastic samples (two diffuse large cell lymphomas, one plasmacytoma) was tested for the following target genes: CD40, Aquaporin-3, BLIMP1, IRF4, Syndecan-1. Delta threshold cycle (DeltaC(T)) values for Bouin-fixed and formalin-fixed paraffin-embedded tissues and their correlation with those for frozen samples showed an extremely high correlation (r > 0.90) for all of the tested genes. These results show that the method of RNA extraction we propose is suitable for giving accurate real time quantitative RT-PCR results.

Effect of silica on virus infections in mice and mouse tissue culture

Silica injections of mice have been reported to kill macrophages, thus allowing herpes simplex virus (HSV) to spread rapidly and leading to an increased severity of HSV infection. Thus, silica presumably could be used to eliminate lactic dehydrogenase virus (LDV) (a model for slow viruses), which is known to multiply exclusively in macrophages. Contrary to expectation, it was found that the LDV titers were increased in silica-injected mice as compared to the titers in control mice. Counts of peritoneal cells at different periods after silica injection showed that silica-induced macrophage damage in vivo resulted in proliferation and migration of macrophages, thus providing additional target cells for LDV replication and leading to high LDV titers. In vitro, silica ingestion also damaged the macrophages, but since no replacement of cells could occur by infiltration, decreased LDV titers were found. Similar findings were obtained with HSV. It is suggested that all persistent viruses multiplying in macrophages will show a similar recrudescence under comparable conditions.

Hydrolytic reactions in two-phase systems. Effect of water-immiscible organic solvents on stability and activity of acid phosphatase, β-glucosidase, and β-fructofuranosidase

The stability and activity of three hydrolytic enzymes, acid phosphatase (EC 3.1.3.2), beta-fructofuranosidase (EC 3.2.1.26), and beta-glucosidase (EC 3.2.1.4), were studied at 30 degrees C in two-phase systems. They were prepared with equal quantities of buffered water and a water-immiscible organic solvent. Low-molecular-weight acetates and paraffins were tested in this investigation. The kinetic constant of storage inactivation was correlated with the logarithm of solvent polarity. Enzyme stability in the presence of organic phases, whose log P value was included in 1.2-2.2, was greater than the one measured in pure buffered aqueous media. On the other hand, a dramatic enzyme denaturation took place making use of solvents at higher log P-value. Experiments carried out during the 24-h operation clarified that the reaction yield does not depend solely on solvent polarity. Acid phosphatase and beta-glucosidase, which are less resistant than beta-fructofuranosidase to temperature and shear in buffered solutions, showed especially significant enhancement of catalytic activity when hydrolysis was performed with the addition of acetates (50% v/v).

Organ-dependent modifying effects of caffeine, and two naturally occurring antioxidants alpha-tocopherol and n-tritriacontane-16,18-dione, on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary and colonic carcinogenesis in female F344 rats

Modifying effects of caffeine, alpha-tocopherol, and n-tritriacontane-16,18-dione (TTAD) on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary and colonic carcinogenesis were investigated in female F344 rats. Groups of 20 rats, 6 weeks old, were given 0.02% PhIP (in diet) alone, or together with 0.1% caffeine (in drinking water), 0.5% alpha-tocopherol (in diet) or 0.1% TTAD (in diet) for up to 54 weeks. Groups of 10 females receiving basal diet or one of the test chemicals without PhIP supplementation were also maintained. The final combined incidences (adenomas plus adenocarcinomas) and multiplicity (No./rat) of mammary adenomas and adenocarcinomas were significantly lowered in the PhIP plus caffeine group (10%, 0.10) as compared to the PhIP alone value (40%, (1.50). Incidences of mammary tumors in the PhIP plus alpha-tocopherol or TTAD groups tended to be decreased while their multiplicities were significantly lowered. With regard to colon tumor development, on the other hand, rats given PhIP plus caffeine exhibited an elevated incidence (75% versus 15% in the control), whereas alpha-tocopherol and TTAD had no effect. Surprisingly, metabolic activation of PhIP was inhibited by addition of caffeine in an in vitro assay. The results indicate that caffeine exerts a potent chemopreventive action against PhIP-induced mammary carcinogenesis, but acts as a co-carcinogen for PhIP-induced colonic carcinogenesis.

The effects of various stimuli on the cellular composition of peritoneal exudates in the mouse

A comparative study on the composition of cell populations collected from the unstimulated mouse peritoneal cavity and at various intervals after the intraperitoneal injection of glycerol trioleate, casein, paraffin oil, glycogen, sodium chloride, and proteose peptone, was carried out. The cellular composition of the peritoneal exudates, especially with respect to the ratio of monocytes to resident macrophages, was shown to be dependent on the nature of the stimulus and interval after stimulation.

Exposure of babies to C15–C45 mineral paraffins from human milk and breast salves

Mineral paraffins widely occur in foods, but are also ingredients of body lotions, lip sticks, and breast salves. In this study it is shown that mineral paraffins are detectable in human milk. Thirty three human milk samples were found to contain mineral C(15)-C(45) paraffins at a mean concentration of 95+/-215mg/kg fat and a maximum of 1300mg/kg. The mineral paraffins found in human milk had average molecular weights between C(23) and C(33), and often more than half of the paraffins were below C(25). Beside exposure of babies via human milk, the intake by direct licking off salves (in the worst case consisting of vaseline) from the breast of their nursing mothers may be much higher. In a worst case situation, daily intake from breast care products by babies is estimated to reach 40mg/kg bw. Many compositions do not comply with the specifications and a temporary group ADI of 0-4mg/kg bw established by the SCF. This possible exposure of babies either calls for a toxicological re-evaluation of the mineral paraffins or for measures ensuring that exposure of babies is reduced.

Effect of tissue fixatives on telomere length determination by quantitative PCR

Telomere length is a well established marker of cellular senescence and thus biological age. Quantitative PCR allows the determination even from very low amounts of tissue by using telomere specific and single copy gene primers. Comparing a directly processed tissue sample to a 4% formaldehyde fixed one showed a significantly reduced efficiency of PCR reactions (mainly in single copy gene experiments) in a storage time-dependent manner resulting in an artificial increase in reported relative telomere length. This effect was not seen when the tissue was stored in RNA later solution. In summary, telomere length determination from formaldehyde fixed material by quantitative PCR is not a reliable method. Unfortunately therefore, many easily accessible tissue samples from pathology laboratories are unsuitable for this technique.

Reduction of skin water loss in the newborn. II. Clinical trial of two methods in very low birthweight babies

Two methods of reducing evaporative water and heat loss in the newborn, the thermal blanket and topical paraffin, were compared in a clinical trial. Forty-four babies weighing less than 1.5 kg, nursed in incubators since birth, were either covered with a plastic bubble blanket or had a paraffin mixture applied to their skin at 6- and 8-hour intervals for the first 2 weeks of life. There was no significant difference between the two groups in terms of mortality, morbidity, weight gain or loss, and temperature control. Two babies in the blanket group were removed from the study because of persistently low body temperatures. Five babies in the paraffin group had minor skin rashes and a further 2 had more extensive rashes which led to their removal from the study. Both methods resulted in good temperature control in babies after the first day of life. In the first 24 hours however, neither method of treatment could prevent subnormal body temperatures in the babies weighing less than 1.0 kg, even though the incubator air temperature was on average more than 1 degree C above the rectal temperature. Other methods are necessary to achieve normal body temperatures in these vulnerable babies.

Cardiovascular effects of acrylic bone cement in rabbits and cats

The cardiovascular responses to forcing acrylic bone cement, Plasticine, or soft paraffin wax into the medullary cavity of the femur have been studied in rabbits and cats. An acute fall in blood pressure, occurring within a few seconds of insertion, was demonstrated with each substance. In a few of the animals the blood pressure response had a second more protracted component and it is suggested that more than one mechanism is involved. The cardiovascular effects that have been observed in man when acrylic cement is used in prosthetic hip surgery also may be due to more than one mechanism.

Fed-batch production of citric acid by Candida lipolytica grown on n-paraffins

This study reports on the effects of fermentor agitation and fed-batch mode of operation on citric acid production from Candida lipolytica using n-paraffin as the carbon source. An optimum range of agitation speeds in the 800-1000 rpm range corresponding to Reynolds numbers of 50000-63000 (based on initial batch conditions) seemed to give the best balance between substrate utilization for biomass growth and citric acid production. Application of multiple fed-batch feedings can be used to extend the batch fermentation and increase final citric acid concentrations and product yield. The three-cycle fed-batch system increased overall citric acid yields to 0.8-1.0 g citricacid/g n-paraffin, approximately a 100% improvement in product yield from those observed in the single cycle fed-batch system and a 200% improvement over normal batch operation. The three-cycle fed-batch mode of operation also increased the final citric acid concentration to 42 g/l from about 12 and 6g/l for single fed-batch cycle and normal batch modes of operation, respectively. Increased citric acid concentrations in three-cycle fed-batch mode was achieved at longer fermentation times.