Mining the microbiota of the neonatal gastrointestinal tract for conjugated linoleic acid-producing bifidobacteria

This study was designed to isolate different strains of the genus Bifidobacterium from the fecal material of neonates and to assess their ability to produce the cis-9, trans-11 conjugated linoleic acid (CLA) isomer from free linoleic acid. Fecal material was collected from 24 neonates aged between 3 days and 2 months in a neonatal unit (Erinville Hospital, Cork, Ireland). A total of 46 isolates from six neonates were confirmed to be Bifidobacterium species based on a combination of the fructose-6-phosphate phosphoketolase assay, RAPD [random(ly) amplified polymorphic DNA] PCR, pulsed-field gel electrophoresis (PFGE), and partial 16S ribosomal DNA sequencing. Interestingly, only 1 of the 11 neonates that had received antibiotic treatment produced bifidobacteria. PFGE after genomic digestion with the restriction enzyme XbaI demonstrated that the bifidobacteria population displayed considerable genomic diversity among the neonates, with each containing between one and five dominant strains, whereas 11 different macro restriction patterns were obtained. In only one case did a single strain appear in two neonates. All genetically distinct strains were then screened for CLA production after 72 h of incubation with 0.5 mg of free linoleic acid ml(-1) by using gas-liquid chromatography. The most efficient producers belonged to the species Bifidobacterium breve, of which two different strains converted 29 and 27% of the free linoleic acid to the cis-9, trans-11 isomer per microgram of dry cells, respectively. In addition, a strain of Bifidobacterium bifidum showed a conversion rate of 18%/microg dry cells. The ability of some Bifidobacterium strains to produce CLA could be another human health-promoting property linked to members of the genus, given that this metabolite has demonstrated anticarcinogenic activity in vitro and in vivo.

Utility of historical vehicle-control data in the interpretation of the local lymph node assay

The accepted approach to the interpretation of local lymph node assay (LLNA) data requires comparison of responses in the test groups with background activity found in concurrent vehicle-treated controls. However, of established value in the interpretation of toxicity test data is the use of historical control values that provide one criterion against which to judge the integrity of individual experiments. Specifically, the availability of robust and relevant historical control data permits examination of whether, in any individual experiment, control values fall within the expected range. With the most commonly used vehicle employed in the LLNA, acetone/olive oil (4 : 1) (v/v), the mean values, standard deviations and normal ranges are increasingly well established for a given laboratory, although there is some variation between laboratories, particularly with regard to expected ranges. Against this background, it is possible to identify (and, if appropriate, eliminate) a concurrent vehicle-control value that falls well outside the expected range. To explore critically the potential merits of this approach, one specific example is examined in detail.

Differential of HIV prevalence in women and men who attended sexually transmitted disease clinics at HIV sentinel surveillance sites in Kenya, 1990-2001

Several studies in sub-Saharan Africa have reported that HIV prevalence in young women is higher than in young men. We used data from Kenya HIV sentinel surveillance conducted from 1990 to 2001 among sexually transmitted disease (STD) patients (15-49 years old) to investigate consistency of gender differentials over time and their risk factors. Of the 15,889 STD patients, the HIV prevalence ranged from 16.0% in 1990 to 41.8% in 1997. The odds ratios (ORs) of HIV infection for women compared to men decreased by age; women 15-24 years were nearly twice as likely as men of the same ages to be HIV infected (OR 1.7 [1.5-2.0]), but risk in those >44 years was almost equal (OR 0.8 [95% CI 0.7-1.2]). The odds of HIV infection for women compared to men were twice in unmarried patients (OR 2.1 [95% CI 1.8-2.3]). This association persisted after controlling for age groups or marital status, residence, level of education, and presence of STD syndromes. This pattern had been consistent over 12 years. Adolescent women with symptoms of STDs should be a focus for the HIV/STD intervention programmes because of their high risk for HIV.

The local lymph node assay: past, present and future

The local lymph node assay (LLNA) was developed originally as a method for the identification of chemicals that have the potential to cause skin sensitization and allergic contact dermatitis. The assay is based on an understanding that the acquisition of contact sensitization is associated with, and dependent upon, the stimulation by chemical allergens of lymphocyte proliferative responses in skin-draining lymph nodes. Those chemicals that provoke a defined level of lymph node cell (LNC) proliferation (a 3-fold or greater increase compared with concurrent vehicle controls) are classified as skin sensitizers. Following its original inception and development, the LLNA was the subject of both national and international interlaboratory collaborative trials, and of very detailed comparisons with other test methods and with human skin sensitization data. The assay has now been validated fully as a stand-alone test for the purposes of hazard identification. In recent years, there has been a growing interest also in the use of the LLNA to assess the potency of contact allergens and in risk assessment. There is reason to believe that the extent of skin sensitization achieved is associated with the vigour of LNC proliferation induced in draining nodes. Given this relationship, the relative potency of skin sensitizing chemicals is measured in the LLNA by derivation of an EC3 value, this being the concentration of chemical required to provoke a 3-fold increase in the proliferation of LNC compared with controls. Experience to date indicates that relative potency as determined using this approach correlates closely with what is known of the activity of skin sensitizing chemicals in humans. In this article, we review the development, evaluation and validation of the LLNA for the purposes of hazard identification, and the more recent application of the method for evaluation of potency in the context of risk assessment. In addition, we consider what new applications and modifications are currently being investigated.

Examination of a vehicle for use with water soluble materials in the murine local lymph node assay

The murine local lymph node assay (LLNA) is a validated method for identifying skin sensitization hazard. Vehicle choice can influence the sensitization potential of haptens in both the LLNA and in humans, therefore selection of an appropriate vehicle is important. Suggested vehicles for the LLNA include organic solvents and organic-aqueous mixtures. However, due to its high surface tension and poor wetting qualities, water is not recommended and therefore testing aqueous soluble materials can be problematic. The aims of this investigation were to identify a water-based vehicle that possesses better skin wetting properties than water alone, and to assess its performance relative to other solvents in the LLNA using aqueous soluble haptens. The selected wetting agent was the surfactant Pluronic(R) L92 (L92). Concentrations of L92 of up to 50% did not induce positive responses in the LLNA. 1% aqueous L92 was chosen for further examination. Dose-response analyses were performed with dinitrobenzene sulfonic acid (DNBS) and formaldehyde formulated either in water, 1% L92, dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF). Potassium dichromate (PDC) and nickel sulfate were tested in 1% L92, DMSO or DMF. The highest concentration of potassium dichromate was retested in each vehicle and in water to assess the effect of the wetting agent. Estimates of the relative sensitizing potency in each vehicle were determined by calculation of EC3 values (the estimated concentration required to induce a threshold positive response). While DNBS and formaldehyde produced positive responses in all four vehicles, their relative potency varied among the vehicles. The rank ordering of potencies for both materials was, from highest to lowest, DMF > or = DMSO > 1% L92 > water. Compared with water, use of 1% L92 resulted in >2-fold increase in potency for DNBS and >3-fold increase for formaldehyde. PDC was positive in DMF, DMSO and 1% L92. The potency ranking was DMF > or = DMSO > 1% L92. Re-evaluation of 0.5% PDC confirmed that formulations of both DMSO and DMF induced strong proliferative responses, whereas somewhat less proliferation was recorded with the 1% L92 vehicle. PDC in water was without activity. The performance of 1% L92 as a vehicle for nickel sulfate was assessed relative to DMSO and DMF. In DMSO, nickel sulfate produced a stimulation index (SI) >3 at only the highest level. Testing in DMF induced low levels of proliferation, but failed to produce a SI of 3 at any concentration tested. When formulated in 1% L92, nickel sulfate caused a SI of 3 when tested at 2.5%. Based on the results of these experiments, for identification of sensitization hazard of aqueous soluble materials using the LLNA, DMF and DMSO are the preferred vehicles. However, if a test material is not soluble in DMF or DMSO, or if higher test concentrations can be achieved in an aqueous vehicle, then 1% L92 may provide a better alternative to water alone in terms of improved assay performance.

Avoiding painful blood sampling in neonates by transcutaneous bilirubinometry

BACKGROUND

Transcutaneous bilirubinometry, Bilicheck (kindly provided by Oxygen Care Company, Dublin) is a non-invasive, screening method for determining bilirubin levels in neonates. It has not previously been validated in Irish babies.

AIMS

To determine the clinical accuracy and precision of Bilicheck measurements in comparison to total serum bilirubin (TSB) measurements in Irish neonates, and to determine whether Bilicheck is a useful non-invasive screening method of avoiding blood tests in neonates.

METHODS

Correlation data were obtained from 53 neonates between simultaneous TSB and Bilicheck readings. Bilicheck was used to screen 100 neonates who were assessed as requiring serum bilirubin measurement. TSB was only performed on neonates whose Bilicheck was above the phototherapy line of a recognised serum bilirubin chart.

RESULTS

Bilicheck and TSB were significantly correlated (r=0.890). Bland and Altman analysis showed that on average, Bilicheck read 30 micromol/l lower than TSB. Of 100 jaundiced neonates screened by Bilicheck, blood sampling was avoided in 70 because Bilicheck did not meet phototherapy guidelines.

CONCLUSIONS

There is a good correlation between TSB and Bilicheck, although the latter tends to under-read by 30 micromol/l. Bilicheck may be a useful screening device to decrease the risks and discomfort associated with blood sampling in neonates.

The feasibility of integrated STI prevalence and behaviour surveys in developing countries

BACKGROUND

In countries where STI/HIV prevalence data and behavioural data are scarce UNAIDS second generation HIV surveillance guidelines recommend measuring STI/HIV prevalence and risk behaviours in vulnerable populations but do not recommend conducting these surveys concurrently because of concerns about participation rates, cost, and provision of services.

OBJECTIVES

To assess the feasibility of conducting a national combined STD prevalence and behaviour survey in Mali among vulnerable populations with the intention of institutionalisation.

METHODS

From March to June 2000 an integrated STI prevalence and behaviour survey was conducted using cluster sampling among five risk groups in four sites in Mali, west Africa. 2229 individuals in non-traditional settings such as taxi/bus stations, market areas, households, and brothels participated in any one or all components of the study: (1) behavioural questionnaire, (2) urine sample for Neisseria gonorrhoeae (GC)/Chlamydia trachomatis (CT) testing, (3) a fingerstick drop of blood for syphilis, and/or (4) HIV testing.

RESULTS

High participation rates of 84%-100% were achieved despite specimen collection and HIV testing. Rates fell only slightly when participants were asked to provide biological samples and participants were more likely to provide urine than blood. Rates among the different groups for HIV and syphilis testing are similar and suggest that refusal was most probably because of a reluctance to give blood rather than because of HIV testing. The cost of the biological component added approximately $30 per participant. Included in the $30 are the costs of training, participant services, laboratory personnel and supplies, STI drugs, and STI testing costs. The total cost of the survey was $154,905. Biomarkers aided in validation of answers to behavioural questions. Consenting individuals received HIV pretest and post-test counselling and referral to a trained health provider for treatment of STI and the provision of services provided the framework for interventions in the groups following the survey.

CONCLUSION

This represents an effective methodology for collecting risk behaviour and STI/HIV prevalence information concurrently and should be considered by countries expanding STI/HIV surveillance as part of UNAIDS second generation HIV surveillance.

Perinatal hepatic infarction in twin-twin transfusion

We report a case of a twin pregnancy which was complicated by a twin-twin transfusion in which the recipient twin was noted to have an intra-abdominal echogenic mass. This twin died at two days of age of hepatic infarction. The donor twin was healthy at birth, at thirty weeks' gestation, and did not have any subsequent problems. Fetal intra-abdominal echogenicity may be a marker of hepatic infarction.

A skin sensitization safety assessment of a new bleach activator technology in detergent applications

A new chemical called nonanoyl amido caproylacid oxybenzenesulphonate (NACAOBS) is being developed for use as a bleach activator in laundry detergents. Bleach activators, like NACAOBS, are typically used at levels between 2% and 6% in laundry detergents. NACAOBS is stable in aqueous solutions, but undergoes rapid perhydrolysis when combined with water and peroxygen bleach in laundry detergents. Animal testing demonstrated that NACAOBS, as a raw material, is a weak skin sensitizer. Clinical testing, including extended simulated laundry pretreatment, human repeat insult patch testing and home use testing was then undertaken, following sufficient reassurance of 1) the weak sensitization potential of the substance, 2) its rapid degradation in laundry wash solutions and, consequently, 3) low-to-negligible consumer dermal exposures to the native substance. Results confirmed the skin sensitization safety profile of laundry detergents containing NACAOBS, namely the absence of any reaction suggestive of contact sensitization (even under exaggerated dermal exposure conditions in a detergent matrix), and a skin compatibility profile comparable to that of current detergents. Further confirmation of the skin safety profile was obtained from a successful 12-month market test of a granular detergent containing 3.6% of the new substance, during which not a single adverse skin reaction was reported. In addition, NOBS (an oxybenzenesulphonate structural analogue to NACAOBS) has similar toxicological properties and has been safely marketed in detergents at similar levels for many years. It can be concluded that the likelihood of NACAOBS to induce skin sensitization or even elicit allergic reactions in consumer detergent use scenarios is negligible.

RALF, a 5-kDa ubiquitous polypeptide in plants, arrests root growth and development

A 5-kDa polypeptide was isolated from tobacco leaves that induced a rapid alkalinization of the culture medium of tobacco suspension-cultured cells and a concomitant activation of an intracellular mitogen-activated protein kinase. An N-terminal sequence was obtained, and a cDNA coding for the 49-aa polypeptide was isolated from a tobacco cDNA library. The cDNA encoded a preproprotein of 115 amino acids that contained the polypeptide at its C terminus. A search among known expressed sequence tags revealed that genes encoding Rapid ALkalinization Factor (RALF) preproproteins were present in various tissues and organs from 16 species of plants representing 9 families. A tomato homolog of the polypeptide was synthesized and, when supplied to germinating tomato and Arabidopsis seeds, it caused an arrest of root growth and development. Although its specific role in growth has not been established, the polypeptide joins the ranks of the increasing number of polypeptide hormones that are known to regulate plant stress, growth, and development.

High rate of bacterial vaginosis among women with intrauterine devices in Manado, Indonesia

Recent research reported that bacterial vaginosis (BV) might enhance the acquisition and transmission of HIV. BV is also associated with an increased risk of pelvic inflammatory disease, a disease also associated with intrauterine device (IUD) insertion. To measure the magnitude of this problem, we conducted a prevalence survey of BV and sexually transmitted diseases (STDs; defined as current infections with Neisseria gonorrhoeae, Chlamydia trachomatis, and/or Trichomonas vaginalis) among all patients attending a family planning clinic in Manado from May to July 1999. BV was diagnosed by Gram stain using Nugent's criteria and vaginal trichomoniasis by wet mount or culture. Cervical infections with C. trachomatis and N. gonorrhoeae were diagnosed by DNA probe. Of 357 patients, 116 (32.5%) had BV, 83 (23.3%) had trichomoniasis, 9 (2.5%) had chlamydia, and 8 (2.2%) had gonorrhea. The prevalence of STD was similar among users of all types of contraception. However, BV was more common among IUD users (47.2%) than among non-IUD users (29.9%). This association persisted after controlling for age, education, ever had douching, and any STD (odds ratio 2.0, 95% CI 1.1-3.8). BV was also associated with STD (41.3% in women with STD vs. 29.4% in women without). This association remained significant after adjusting for age, education, ever had douching, and IUD use (odds ratio 1.7, 95% CI 1.1-2.9). Because we found that BV was associated with IUDs and that other studies reported that both BV and IUDs were associated with pelvic inflammatory disease, a Gram stain evaluation of BV may be considered prior to IUD insertion

Healing response to the Clamshell device for closure of intracardiac defects in humans

The healing response to intracardiac devices in humans is largely unknown. During regulatory trials using the Clamshell device in over 800 patients, attempts were made to perform histopathological evaluation of all explanted devices. We reviewed all those with complete histopathological examination (n = 12) from Fontan baffles (n = 4), ventricular septal defects (n = 2), and atrial septal defects (ASD; n = 6), explanted at 2.7 months to 3.6 years (median, 1.6 years), at autopsy (n = 1) or surgery (n = 11), performed for residual defects (n = 5), atrial masses (n = 3), or Fontan revision (n = 3). All but one were nearly (n = 3) or completely (n = 8) covered by pseudointima, composed of fibroelastic tissue, predominantly collagen, with focal foreign body reaction in contact with fabric, without acute inflammation or infection. Atrial masses of granulation tissue were present in three cases (ASD), opposite to protruding fractured arms. No associations were identified between coverage and closure status, position, arm fractures, or implant period. In conclusion, the healing response to transcatheter Clamshell implantation in humans is characterized by a relatively rapid development of a nonthrombotic pseudointima composed of fibroelastic tissue with minimal foreign body reaction. Cathet Cardiovasc Intervent 2001;54:101-111.

Contact allergenic potency: correlation of human and local lymph node assay data

BACKGROUND

Effective toxicologic evaluation of skin sensitization requires that potential contact allergens are identified and that the likely risks of sensitization among exposed populations are assessed. By definition, chemicals that are classified as contact sensitizers have the capacity to cause allergic contact dermatitis (ACD) in humans. However, this hazard is not an all-or-nothing phenomenon; clear dose-response relationships can be discerned and thresholds identified for both the induction of sensitization and the elicitation of ACD. Commonly, these parameters are grouped under the heading of potency, the determination of which is vital for risk assessment. Preclinical testing for sensitization potential is critically important for hazard assessment before human exposure. The murine local lymph node assay (LLNA) is the most recently accepted test method for sensitization hazard assessment.

OBJECTIVE

The aim was to compare potency estimations derived from LLNA data with clinical determinations of relative potency based on human data.

METHODS

No-effect levels (NOELs) for a range of 21 chemicals were determined from nondiagnostic human repeat patch test studies as reported in the literature. These levels were compared with LLNA EC(3) values, the estimated concentration required to produce a 3-fold increase (positive response) in draining lymph node cell (LNC) proliferative activity.

RESULTS

Using available human repeat patch test data, together with expert judgment, the compounds were classified as strong, moderate, weak, extremely weak, or nonsensitizing. Additionally, the potency of each chemical was classified independently based on its LLNA EC(3) value. The results show clearly that LLNA EC(3) values are very comparable with the NOELs calculated from the literature. Moreover, the potency rankings based upon LLNA EC(3) data support their human classification.

CONCLUSION

The present investigations show that the LLNA can be used to provide quantitative estimates of relative skin sensitizing potency EC(3) values that correlate closely with NOELs established from human repeat patch testing and from our clinical experience.

Using tasks to measure consumers' ability to apply food guide recommendations: lessons learned

This article reports on lessons learned from using comparison and substitution tasks to assess consumers' ability to apply food guide messages. The study evaluated the usability of the Northeast Regional Food Guide (NERFG), which provides instruction on healthful diets of local foods in season. The tasks showed that the NERFG is useful for daily life decisions. Lessons learned were that the scores on tasks need to better differentiate between groups. The validity and reliability of the tasks should be established in future research. The use of tasks may also be appropriate for educational purposes.

Human potency predictions for aldehydes using the local lymph node assay

The murine local lymph node assay (LLNA) assesses skin sensitization potential as a function of proliferative responses induced in lymph nodes draining the site of topical exposure to test chemical. It has been shown that interpolation of LLNA dose-response data to define the concentration of test chemical required to induce a 3-fold stimulation of proliferation (EC3) offers the prospect of a quantitative index of the relative potency of a contact allergen. Initial studies have demonstrated that there exists a strong (inverse) correlation between EC3 values and contact allergenic potency in humans. Thus, materials with a low EC3 value were more potent contact allergens in humans. However, it is necessary to examine a wide range of allergens to demonstrate that such correlations are generally true. Thus, in the present study, 10 aldehydes of varying degrees of allergenicity in man were evaluated in the LLNA and their EC3 values derived. Formaldehyde was regarded as the strongest allergen in man and also had the lowest EC3 value, 0.35% (equivalent to 0.93% formalin). In contrast, the extremely weak allergen vanillin and the non-sensitizer ethyl vanillin both had EC3 values of >50%. For the remaining 7 aldehydes, there was a close similarity between what is judged to be their rank order of allergenicity in humans and EC3 values derived from analysis of LLNA data. These results support further the utility of EC3 determinations in the LLNA as a measure of the relative potency of a contact allergen.

Production of multiple plant hormones from a single polyprotein precursor

Some animal and yeast hormone genes produce prohormone polypeptides that are proteolytically processed to produce multiple copies of hormones with the same or different functions. In plants, four polypeptides have been identified that can be classed as hormones (intercellular chemical messengers) but none are known to be produced as multiple copies from a single precursor. Here we describe a polyprotein hormone precursor, present in tobacco plants, that gives rise to two polypeptide hormones, as often found in animals and yeast. The tobacco polypeptides activate the synthesis of defensive proteinase-inhibitor proteins in a manner similar to that of systemin, an 18-amino-acid polypeptide found in tomato plants. The two tobacco polypeptides are derived from each end of a 165-amino-acid precursor that bears no homology to tomato prosystemin. The data show that structurally diverse polypeptide hormones in different plant species can serve similar signalling roles, a condition not found in animals or yeast.

The suitability of hexyl cinnamic aldehyde as a calibrant for the murine local lymph node assay

The murine local lymph node assay (LLNA) for the prospective identification of contact allergens assesses skin sensitization potential as a function of proliferative activity induced in lymph nodes draining the site of topical exposure to test chemical. This method has been endorsed recently as a stand alone test for the identification of contact allergens. We have now examined the suitability of hexyl cinnamic aldehyde (HCA), a recommended positive control for skin sensitization testing, as a calibrant for comparing the consistency of LLNA responses with time, and between laboratories, and thus for the routine assessment of assay reliability. Standard LLNAs were performed with CBA strain mice in 3 independent laboratories over a period of 8 years. Dose-response curves were used to derive mathematically the EC3 value (the estimated concentration of chemical necessary to cause a stimulation index (SI) of 3 compared with proliferation induced by concurrent vehicle controls). In each laboratory, 6 separate experiments were conducted using a single concentration of HCA (25%). Very similar stimulation indices were achieved, with mean values of 9.0, 6.5 and 6.6 recorded. A total of 10 dose-response experiments were performed independently in the 3 laboratories and these revealed that there was very little inter-laboratory, or temporal, variation in EC3 values. These data confirm that HCA responses in the LLNA are very stable and demonstrate that HCA provides a suitable calibrant for determining assay sensitivity and performance.

Proteinase inhibitors I and II from potatoes block UVB-induced AP-1 activity by regulating the AP-1 protein compositional patterns in JB6 cells

Proteinase inhibitor I (Inh I) and proteinase inhibitor II (Inh II) from potato tubers are effective proteinase inhibitors of chymotrypsin and trypsin. Inh I and Inh II were shown to suppress irradiation-induced transformation in mouse embryo fibroblasts suggesting that they possess anticarcinogenic characteristics. We have previously demonstrated that Inh I and Inh II could effectively block UV irradiation-induced activation of transcription activator protein 1 (AP-1) in mouse JB6 epidermal cells, which mechanistically may explain their anticarcinogenic actions. In the present study, we investigated the effects of Inh I and Inh II on the expression and composition pattern of the AP-1 complex following stimulation by UV B (UVB) irradiation in the JB6 model. We found that Inh I and Inh II specifically inhibited UVB-induced AP-1, but not NFkappaB, activity in JB6 cells. Both Inh I and Inh II up-regulated AP-1 constituent proteins, JunD and Fra-2, and suppressed c-Jun and c-Fos expression and composition in bound AP-1 in response to UVB stimulation. This regulation of the AP-1 protein compositional pattern in response to Inh I or Inh II may be critical for the inhibition of UVB-induced AP-1 activity by these agents found in potatoes.

Separation of histone variants and post-translationally modified isoforms by triton/acetic acid/urea polyacrylamide gel electrophoresis

Due to their similarities in size and charge, complete resolution of histones by electrophoresis poses a considerable challenge. The addition of nonionic detergents to the traditional acetic acid/urea (AU) polyacrylamide gel electrophoresis (PAGE) system has afforded an excellent method to separate not only the different modified forms of histones, but also the primary sequence variant subtypes of selected histone species; it is widely used to separate histones with varying levels of acetylation. This unit describes the use of gels containing the nonionic detergent Triton X-100, referred to as Triton/acetic acid/urea (TAU) polyacrylamide gels, for analysis of histones. Also included are support protocols detailing several accessory techniques: assembly of gel plates for the TAU gel, preparation of histones from isolated nuclei in a solubilized form amenable to electrophoresis, and electrophoretic transfer of proteins from these gels to PVDF membranes.

Wound-inducible proteinase inhibitors in pepper. Differential regulation upon wounding, systemin, and methyl jasmonate

Seven small (approximately 6,000 D) wound-inducible proteinase inhibitor proteins were isolated from leaves of pepper (Capsicum annuum) plants that are members of the potato inhibitor II family. N-terminal sequences obtained indicated that the pepper leaf proteinase inhibitors (PLPIs) exhibit homology to two GenBank accessions that code for preproteins containing three isoinhibitors domains each that, when post-translationally processed, can account for the mixture of isoinhibitors that are reported herein from pepper leaves. A constitutive level of PLPI proteins was found in pepper leaves, and these levels increased up to 2.6-fold upon wounding of the lower leaves. Exposing intact plants to methyl jasmonate vapors induced the accumulation of PLPIs. Supplying excised young pepper plants with water through the cut stems induced PLPI proteins to levels higher than those found in intact plants, but with high variability. Supplying the excised plants with systemin did not result in an increase of PLPI levels that were statistically higher than levels found in excised plants. Gel-blot analyses of PLPI induction revealed the presence of two mRNA bands, having slightly different mobilities in agarose gels. Only the low M(r) mRNA is present in untreated control plants, and it appears to be responsible for the constitutive levels of PLPI found in leaves. Both mRNA species are wound- and methyl jasmonate-inducible. Only the low- M(r) species is weakly induced by systemin, indicating a differential expression of the two PLPI species.

Cytokine induction of a human acute myelogenous leukemia cell line (KG-1) to a CD1a + dendritic cell phenotype

Dendritic cells (DC) are highly specialized antigen-presenting cells located in many nonlymphoid tissues, and Langerhans cells (LC), a specialized form of DC, are found in the skin. LC as antigen-presenting cells play a critical role in the induction of allergic contact dermatitis. LC research is difficult because few LCs can be isolated from human skin, so efforts have focused on obtaining DCs from alternative sources. Mononuclear cells from peripheral blood and CD34+ stem cells from human cord blood and marrow can be induced to form phenotypic and functional DCs, but experiments of this type are expensive and the DC yield is low. We report here the induction of the myeloid leukemia cell line (KG-1) to a DC morphology and phenotype by culturing the cells in a defined cytokine cocktail. Morphologically, the KG-1-derived DCs are large irregularly shaped cells with prominent dendritic processes and hair-like cytoplasmic projections. Phenotypically, the KG-1-derived DCs lack lineage-specific markers, and express MHC class II, costimulatory molecules CD80 and CD86, and CD83. Functionally, KG-1-derived DCs are capable of phagocytosing latex microspheres and are able to induce a potent allogeneic T-cell response. Within the KG-1-derived DCs, a subpopulation maintains the DC phenotype and morphology described above but further develops CD1a+ marker expression similar to that of resident skin-derived LCs. These findings illustrate that phenotypic, morphologic and functional DCs can be derived from the KG-1 cell line.

Approaches for the development of cell-based in vitro methods for contact sensitization

Allergic contact dermatitis (ACD) is a cell-mediated immune response to small molecular weight chemicals that contact and penetrate the skin. There are a variety of characteristics that determine whether a chemical can function as a contact sensitizer (or allergen) including the ability to penetrate into the skin, react with protein and be recognized as antigenic by immune cells. The ultimate challenge for developing non-animal test methods for skin sensitization testing will be applying our mechanistic understanding of ACD to the design of predictive in vitro alternative test methods. Specifically, the in vitro approach should be designed so that a chemical's potential to penetrate the skin, react with protein/peptide (biotransformation may be required) and initiate an antigen-specific immune response is incorporated in the test methods developed. In this review, we have focused on cellular-based assays that have been developed or proposed for assessing a chemical's skin sensitization potential in vitro. All of the promising leads to date are based on observations made from in vivo studies conducted in animals and humans, and therefore have a strong mechanistic foundation. However, it remains to be demonstrated whether a single in vitro test, or several in vitro tests in combination, which model the critical steps in sensitization, can replace animal experiments for predicting contact allergic reactions in humans. Regardless, the future looks promising with continued development of our understanding of the chemical and biological aspects of allergic contact dermatitis, and most importantly, with the application of genomics/proteomics to this field on the immediate horizon.