Ventilator-Associated Pneumonia in the Neonatal Intensive Care Unit-Incidence and Strategies for Prevention.

The second most prevalent healthcare-associated infection in neonatal intensive care units (NICUs) is ventilator-associated pneumonia (VAP). This review aims to update the knowledge regarding the incidence of neonatal VAP and to summarize possible strategies for prevention. The VAP incidence ranges from 1.4 to 7 episodes per 1000 ventilator days in developed countries and from 16.1 to 89 episodes per 1000 ventilator days in developing countries. This nosocomial infection is linked to higher rates of illness, death, and longer hospital stays, which imposes a substantial financial burden on both the healthcare system and families. Due to the complex nature of the pathophysiology of VAP, various approaches for its prevention in the neonatal intensive care unit have been suggested. There are two main categories of preventative measures: those that attempt to reduce infections in general (such as decontamination and hand hygiene) and those that target VAP in particular (such as VAP care bundles, head of bed elevation, and early extubation). Some of the interventions, including practicing good hand hygiene and feeding regimens, are easy to implement and have a significant impact. One of the measures that seems very promising and encompasses a lot of the preventive measures for VAP are the bundles. Some preventive measures still need to be studied.

Extrahepatic Portal Vein Thrombosis in Childhood: Risk Factors, Clinical Manifestations, and Management.

OBJECTIVE: Extrahepatic portal vein thrombosis (EHPVT) is a common cause of portal hypertension in children. The aim of the present study was to identify the clinical manifestations and the risk factors for development of EHPVT in pediatric patients. SUBJECTS AND METHODS: This was a single-center retrospective cohort study. A total of 12 children (6 boys and 6 girls) took part in the study. We noted the clinical presentations and the predisposing risk factors for development of EHPVT in all patients. In addition, as all of them had undergone an esophagogastroduodenoscopy for detection and grading of esophageal varices as part of the treatment algorithm, we analyzed the endoscopic findings and the therapeutic approach. RESULTS: The median age of subjects at diagnosis was 3.5 years (range: 1-17 years). The most frequent initial clinical manifestation was upper gastrointestinal bleeding (6 cases, 50.0%) followed by splenomegaly (3 cases, 25.0%). The most frequent systemic risk factor for EHPVT was presence of inherited prothrombotic disorder (10 cases, 83.3%), and the most common local risk factor for EHPVT was umbilical vein catheterization (5 cases, 41.7%). Esophageal varices were revealed in all the study participants, and in the most cases, they were grade ≥2. Propranolol was used as primary or secondary prophylaxis in 7 children (58.3%), and in 5 children (41.7%), a shunt was performed (Meso-Rex bypass in 3 children and splenorenal shunt in 2 children). CONCLUSION: Patients with known systemic or local risk factors for EHPVT are indicated for proactive ultrasound screening for early diagnosis and timely management.

Ventilator-Associated Pneumonia in Neonates Admitted to a Tertiary Care NICU in Bulgaria.

Ventilator-associated pneumonia (VAP) is the second most common hospital-acquired infection (HAI) among neonatal patients in the intensive care units (ICUs) and is a serious challenge for neonatologists because it affects critically ill patients who need prolonged mechanical ventilation. In Bulgaria, there is no detailed data at regional and national levels on the characteristics of VAP in newborns, which imposes a necessity for specific studies of risk factors and etiology of VAP. The aim of the study was to analyze the frequency, characteristics and risk factors for the occurrence of VAP in newborns hospitalized in intensive care unit. This was a prospective study, conducted between January 2017 and June 2018 in the NICU of University Hospital "St. George" Plovdiv, Bulgaria. The sample consisted of 507 neonates, followed up prospectively, 107 of whom were placed on mechanical ventilation for ≥48 h. VAP was diagnosed in 33 out of 107 neonates (31%). The VAP incidence rate was 35.06/1.000 ventilator days. We confirmed differences between the median birth weight (1,310 vs. 1,690 g, p = 0.045) and average gestational age (31.08 g.w. vs. 33.08 g.w, p = 0.04) of the patients with and without VAP. The average stay of patients with VAP in the NICU was statistically significantly longer than the hospital stay of non-VAP patients (35.70 ± 21.84 days vs. 21.77 ± 17.27 days (t = 3.241, p = 0.002). In neonates with VAP, the duration of mechanical ventilation was statistically significantly longer compared with non-VAP patients (16.88 ± 11.99 vs. 5.42 ± 4.48; t = 5.249, p = 0.000). A statistically significant prevalence of Gram-negative bacteria among VAP patients was demonstrated (91%) compared to the Gram-positive (9%), p < 0.05. The leading causative agent of VAP was Klebsiella pneumoniae ESBLs + (27%), followed by Acinetobacter baumannii (14%), Pseudomonas aeruginosa (12%) and Escherichia coli (12%). In multivariate logistic regression, mechanical ventilation >7 days was established as an independent risk factor for VAP (OR 3.6; 95% CI: 1.7-6.5, p = 0.003). VAP remains a serious and outstanding issue in pediatric and neonatal intensive care units. The findings of the current study emphasize that the birth weight, gestational age, and duration of hospital stay have a significant association with ventilator-associated pneumonia.

Contact allergy to hair-colouring products: a cosmetovigilance follow-up study by four companies in Europe from 2014 to 2017.

BACKGROUND: A previous analysis of undesirable events (UEvs), reported to four major companies following the use of hair-colouring products in Europe, showed that the reporting rates were stable for both oxidative and direct hair-colouring products over the period 2003-2006. OBJECTIVES: In order to verify the impact of risk management measures implemented since 2006, as well as the impact of a new Commission Regulation (No 1223/2009), the same four companies analysed cosmetovigilance data collected over an additional four-year period (2014-2017). The objective was to determine whether there was any time effect, country effect, or product type effect, as well as identify risk factors. MATERIALS AND METHODS: Each company collected reports of alleged UEvs, undesirable effects (UEfs) and serious undesirable effects (SUEs) for their products in their key European markets, and calculated the respective reporting rates (number of events/million units sold). A detailed analysis was performed on allergic contact dermatitis-type events. RESULTS: The reporting rates for alleged UEvs and allergic-type UEfs associated with hair-colouring products remained stable over the four-year period, although a statistically significant decrease was observed for some companies. No time effect on SUEs was observed for three companies but a statistically significant decrease in SUEs was observed for one company. Black henna tattoos remained a major risk factor regarding SUEs due to hair dyes. CONCLUSION: The reporting rates of undesirable events, including contact allergy-type events, were stable over time. This was true for oxidative and direct hair dyes, for both home use and professional exposure scenarios.

Surveillance of Nosocomial Infections in a Bulgarian Neonatal Intensive Care Unit.

INTRODUCTION: Nosocomial infections (NI) are frequent complications in neonatal intensive care units (NICU) which result in high morbidity and mortality. AIM: To determine and analyze the incidence, risk factors and etiologic agents of NI in newborns admitted in the NICU to help plan-ning future surveillance and prevention strategies. MATERIALS AND METHODS: A prospective cohort study was carried out at the NICU of St George University Hospital, Plovdiv, Bul-garia from January 1, 2017 to June 31, 2018. The number of neonates included in the study was 507. Descriptive statistics such as count,  percent, mean and standard deviation was used. Chi-square test was performed to prove associations. Odds ratios, with 95% confidence intervals, were computed from the results of the binominal logistic regression analyses. RESULTS: Of the 507 hospitalized newborns in NICU, 48 presented with 54 NI. The incidence and the density incidence rates were 9.5% and 7.67 per 1,000 patient-days, respectively. Nosocomial infections were detected in neonates from all birth weight (BW) classes, but it was low BW and premature neonates that were at major risk to acquire them. The most common infection sites were ventilator-asso-ciated pneumonia (VAP) (67.27%), bloodstream infection (23.64%) and conjunctivitis (9.09%). Major pathogens were Gram-negative such as Klebsiella pneumoniae, E. coli, Pseudomonas aeruginosa and Acinetobacter baumannii. In the multivariate logistic regression analysis NIs were strongly associated with intubation, presence of a venous catheter, the duration of antibiotic treatment and increased CRP> 10 mg/l. CONCLUSIONS: This report highlights the burden of NIs, identifies the major focus for future NI control and prevention programs.

Allergy Alert Test for p-Phenylenediamine-Allergic Hair Dye Users.

BACKGROUND: Contact dermatitis to hair dyes remains a health concern. Regulations in many countries require consumer self-testing for hair dyes, but no standardized procedure exists. OBJECTIVE: The aim of this study was to develop a self-test protocol for an allergy alert test (AAT) that can elicit a self-noticeable alert signal in p-phenylenediamine (PPD)-allergic consumers. METHODS: Simulating consumer use conditions (open application for 45 minutes after mixing with a developer), PPD-positive hair dye-allergic subjects and PPD-negative control subjects were tested on the forearm and behind the ear with experimental products containing 0.05%, 0.25%, 0.75%, and 2% PPD. Reactions were self-evaluated by subjects and independently assessed by dermatologists. CONCLUSIONS: The AAT caused a reaction self-noticeable on the forearm in 90.5% (38/42) and behind the ear in 93% (39/42) of the PPD-positive subjects. This was objectified by a dermatological evaluation. The strength of the AAT response and the number of responding subjects increased with increasing PPD concentrations. Allergy alert test responses were also dependent on the reaction strength of the diagnostic patch test to PPD before the study; in subjects with (+++) patch test reactions, 19 of 19 were positive. All 48 control subjects were negative to the AAT. Therefore, the AAT protocol provides a signal indicative of an allergic reaction in PPD-allergic hair dye consumers.

Skin sensitization quantitative risk assessment for occupational exposure of hairdressers to hair dye ingredients.

Occupational exposure of hairdressers to hair dyes has been associated with the development of allergic contact dermatitis (ACD) involving the hands. p-Phenylenediamine (PPD) and toluene-2,5-diamine (PTD) have been implicated as important occupational contact allergens. To conduct a quantitative risk assessment for the induction of contact sensitization to hair dyes in hairdressers, available data from hand rinsing studies following typical occupational exposure conditions to PPD, PTD and resorcinol were assessed. By accounting for wet work, uneven exposure and inter-individual variability for professionals, daily hand exposure concentrations were derived. Secondly, daily hand exposure was compared with the sensitization induction potency of the individual hair dye defined as the No Expected Sensitization Induction Levels (NESIL). For PPD and PTD hairdresser hand exposure levels were 2.7 and 5.9 fold below the individual NESIL. In contrast, hand exposure to resorcinol was 50 fold below the NESIL. Correspondingly, the risk assessment for PPD and PTD indicates that contact sensitization may occur, when skin protection and skin care are not rigorously applied. We conclude that awareness of health risks associated with occupational exposure to hair dyes, and of the importance of adequate protective measures, should be emphasized more fully during hairdresser education and training.

The 5-minute Apgar Score as a Prognostic Factor for Development and Progression of Retinopathy of Prematurity.

BACKGROUND: A low Apgar score at 5 minutes has been shown to be a risk factor for development of retinopathy of prematurity (ROP). AIM: To examine the prognostic value of Apgar score at 5 minutes for development and progression of ROP. MATERIALS AND METHODS: The study included 132 preterm infants who were screened from 4th week of life onward. Of these, 118 newborns were given Apgar score at 5 minutes. The prognostic significance of this index was studied as an absolute value and as a value ≤ 6. The patients were divided into two groups: group I had no evidence of ROP (n=82) and group II had some signs of ROP (n = 36). Group II was further divided into group IIA - spontaneously regressed cases (n=22), and group IIB with cases which progressed to treatment stages (n=14). We investigated 15 maternal and 20 newborn presumable risk factors for development and progression of ROP. Mann-Whitney U test, χ2 or Fisher's exact test were used in the statistical analysis. Logistic regression was performed to find significant and independent risk factors for manifestation and progression of ROP. RESULTS: A low 5-minute Apgar score and an Apgar score of 6 or less at 5 minutes were not statistically significant risk factors of ROP (р=0.191, р=0.191, respectively), but were significant risk factors for the manifested ROP to progress to stages requiring treatment (p=0.046, р=0.036, respectively). CONCLUSION: An Apgar score at 5 minutes of 6 or less was a significant and independent risk factor for progression of ROP to stages requiring treatment.

Vulvovaginal Candidiasis in Pregnant Women and its Importance for Candida Colonization of Newborns.

UNLABELLED: Vulvovaginal candidiasis is the second most common cause of vaginitis worldwide (after bacterial candidiasis). Maternal vulvovaginal candidiasis is a major risk factor for Candida colonization and infection of the infant where prognosis depends on different predisposing factors. The aim of this study was to determine the incidence and the etiological structure of vulvovaginal candidiasis in pregnant women and its impact on Candida colonization of newborns. MATERIALS AND METHODS: Samples of vaginal secretions from 80 healthy pregnant women who were clinically suspicious for Candida vaginitis were collected within 48 hours before delivery. Samples for probable Candida colonization from the oral mucosa and feces were collected from their newborns within 47-72 hours after birth. Samples were plated on Sabouraud agar, followed by species identification by API Candida yeast assay. RESULTS: Twenty-three (28.75 ± 5.06%) of the evaluated pregnant women were positive for Candida spp. Positive samples for Candida colonization were found in 18 (22.22 ± 4.62%) of the examined 81 newborns (one pair of twins) from mothers who were clinically suspicious for vaginal candidiasis. Isolates of the newborns were 100% identical to those of the mothers' vaginal secretion. Candida albicans was the predominant species identified in the pregnant women (91.67 ± 0.06%) and in the neonates (83.33±8.78%).

Somatosensory evoked potentials in full-term neonates with perinatal asphyxia.

OBJECTIVE: To explore the capacity of somatosensory evoked potentials (SEP) to assess maturation processes in the development of the nervous system, and the characteristics of SEP in healthy full-term infants and full-term newborns with perinatal asphyxia and their follow up until the age of 14 months. MATERIALS AND METHODS: SEP were studied in 21 healthy full-term infants and 38 full-term newborns with perinatal asphyxia. The children with asphyxia were studied longitudinally until they were 14 months old. To assess the SEP we measured the latency of the P15, N20 and P25 components, the amplitude ratio N20/P25 and inter-peak intervals P15-N20 and N20-P25. RESULTS: The component that was most typically always found in the SEP recordings of both healthy infants and those with perinatal asphyxia was N20. The mean latency values of P15, N20 and P25 were higher in the children with perinatal asphyxia (p < 0.001). The SEP amplitude was highly variable (CoV% = 76.6%). The latencies became shorter with age in asphyxia patients aged 0 to 14 months, the shortening being the greatest in the first trimester, while they showed no statistically significant differences in infants aged 6 to 12 months. CONCLUSIONS: SEPs in the neonatal period differ considerably from those of adults and older children in the morphology and longer potential latency, which can be accounted for by the incomplete myelination of nerve fibers. The changes in SEP latency in patients with HIE stages I and II follow the same pattern found in healthy children--latency became shorter with increasing age, which was most pronounced in the first 3 months. SEP latency was found to be correlated with height and age. No differences were found in the latency of potentials between healthy infants and infants with brain hemorrhage. Recording SEP is a sensitive method to assess the CNS in children with perinatal asphyxia and to monitor the maturation of the somatosensory pathway.

Quantitative risk assessment for skin sensitisation: consideration of a simplified approach for hair dye ingredients.

With the availability of the local lymph node assay, and the ability to evaluate effectively the relative skin sensitizing potency of contact allergens, a model for quantitative-risk-assessment (QRA) has been developed. This QRA process comprises: (a) determination of a no-expected-sensitisation-induction-level (NESIL), (b) incorporation of sensitization-assessment-factors (SAFs) reflecting variations between subjects, product use patterns and matrices, and (c) estimation of consumer-exposure-level (CEL). Based on these elements an acceptable-exposure-level (AEL) can be calculated by dividing the NESIL of the product by individual SAFs. Finally, the AEL is compared with the CEL to judge about risks to human health. We propose a simplified approach to risk assessment of hair dye ingredients by making use of precise experimental product exposure data. This data set provides firmly established dose/unit area concentrations under relevant consumer use conditions referred to as the measured-exposure-level (MEL). For that reason a direct comparison is possible between the NESIL with the MEL as a proof-of-concept quantification of the risk of skin sensitization. This is illustrated here by reference to two specific hair dye ingredients p-phenylenediamine and resorcinol. Comparison of these robust and toxicologically relevant values is therefore considered an improvement versus a hazard-based classification of hair dye ingredients.

Contact allergy to hair colouring products. The cosmetovigilance experience of 4 companies (2003-2006).

The post-marketing undesirable events to hair colouring products in the European Union notified to the cosmetovigilance departments of four major cosmetic companies were analysed (2003-2006). The objective was to determine whether there was any time effect (trend to increase or decrease), country effect (significant difference between the countries included in the analysis) or product type effect (direct or oxidation), as well as to identify risk factors. Alleged undesirable events (UEvs, all notifications prior to causality assessment), were compared to the respective undesirable effects (UEfs, reasonably attributable to product use). A detailed analysis was performed on notifications with manifestations compatible with allergic contact dermatitis. No time effect of UEvs and UEfs was shown, for all hair-dye associated notifications and for allergic contact dermatitis, for all hair colouring products together and by product type. The incidence of allergic contact dermatitis to direct hair colouring products was lower for all four companies compared to oxidative hair dyes. The reporting rates of UEfs were statistically higher in the UK for one of four companies. Past history of black henna tattoos appeared as a major risk factor for seriousness of allergic contact reactions.

Consumer allergy to oxidative hair coloring products: epidemiologic data in the literature.

Oxidative hair dyes have repeatedly come to the attention of the dermatologic community owing to concerns about contact dermatitis. A review of the scientific literature provides insight into the prevalence of p-phenylenediamine (PPD)-sensitized individuals and on the prevalence of hair dye dermatitis in various types of patient and nonpatient populations mainly from Europe and from the United States and Asia. Most of the results are obtained through patch testing with PPD. PPD is one of the main oxidation colorants; however, patch-test prevalence of PPD is not equivalent to prevalence of hair dye allergy. An analysis shows no clear increase in the frequency of positive patch-test reactions to PPD in eczema patients and in the general population. All the parameters through which the frequency of hair dye dermatitis resulting from exposure to PPD is evaluated have been stable in Europe, with a few exceptions that are discussed in the review. There is a statistically significant decrease (p < .0001) in the prevalence of positive patch-test reactions to PPD in North America (1970 to 2002). Data from studies in Asia are difficult to interpret. Pooled prevalence rates of positive patch-test reactions to PPD were calculated for the three continents.

A double-blind, randomized assessment of the irritant potential of sunscreen chemical dilutions used in photopatch testing.

BACKGROUND: The maximum concentration of organic sunscreen filters in current usage that does not lead to irritant reactions when performing photopatch testing is not known. Such irritant reactions can be misinterpreted as positive photoallergic contact dermatitis reactions. OBJECTIVE: To determine the frequency of irritant reactions to 19 organic sunscreen filters in current use. PATIENTS/METHODS: Ninety-four healthy volunteers were photopatch tested using the European consensus methodology to three different concentrations (2%, 5%, and 10%) of 19 organic sunscreen filters at the Photobiology Unit in Dundee, UK. RESULTS: Of the 94 subjects recruited, 80 were analysed after withdrawals and exclusions. Of the 19 organic sunscreen filters studied, only 2 compounds led to irritant reactions in > or =5% subjects. Five per cent and 10% benzophenone-4 led to irritant reactions in four and six subjects, respectively. Five per cent methylene bis-benzotriazolyl tetramethylbutylphenol led to irritant reactions in six subjects, but unlike benzophenone-4, this was not in a dose-dependent fashion. CONCLUSIONS: When performing photopatch testing according to the European consensus methodology with these 19 organic sunscreen filters, a 10% concentration is suitable for all filters, except benzophenone-4, which should be tested at a concentration of 2%.

Sensitivity and specificity of the consumer open skin allergy test as a method of prediction of contact dermatitis to hair dyes.

To prevent contact dermatitis to oxidative hair colouring products, a consumer test (skin allergy test, SAT) consisting of the open application of the colourant base prior to mixing with the developer is recommended 48 hours before hair colouring. We investigated the sensitivity and specificity of the SAT to detect and prevent contact allergy to oxidative hair colouring products that contained a range of concentrations of para-phenylenediamine (PPD) and corresponded to different shades (light, medium and dark). Test colouring products containing increasing concentrations of PPD (0.1, 0.5, 1.0 or 1.5%) were applied to 34 PPD-positive hair dye-allergic individuals and to 49 non-allergic control subjects. Allergic reactions were elicited in all PPD-positive subjects whereas none occurred in control PPD-negative subjects. For each subject the eliciting concentration of PPD in the SAT was compared with the PPD concentration range of the group of commercial shades reported as causing reactions by the consumer. In all PPD-positive subjects the eliciting concentrations of PPD in the SAT was within or lower than the range of PPD concentrations in the reported eliciting colourant base of commercial products. In conclusion, our results confirm the excellent predictive value of the SAT over the entire range of PPD concentrations used in oxidative hair colouring products and suggest that the test is a suitable tool for the secondary prevention of contact allergic reactions to hair colouring products.

Allergic contact dermatitis.

Contact dermatitis is an inflammatory skin condition induced by exposure to an environmental agent. Eczema and dermatitis are used synonymously to denote a polymorphous pattern of skin inflammation characterized at least in its acute phase by erythema, vesiculation and pruritus. Substances responsible for contact dermatitis after single or multiple exposures are non protein chemicals, i.e. haptens, that induce skin inflammation through activation of innate skin immunity (irritant contact dermatitis) or both innate and acquired specific immunity (allergic contact dermatitis). The present review will focus on allergic contact dermatitis, a delayed-type hypersensitivity reaction, which is mediated by hapten-specific T cells. Recent advances in the pathophysiology of ACD have shown that the occurrence of ACD, as well as its magnitude and duration, is controlled by the opposite functions of CD8 effector T cells and CD4 regulatory T cells. From these studies ACD can be considered as a breakdown of cutaneous immune tolerance to haptens.

Contact sensitivity to hair dyes can be detected by the consumer open test.

To avoid allergic reactions to hair dyes, an open test ("skin sensitivity test" or "dab test") is recommended 48 hours before the hair colouring procedure. We have investigated in a multicenter study, under standardized conditions and medical supervision, the validity of this test as a practical method to detect allergy to paraphenylenediamine (PPD)-containing hair dyes in 30 PPD patch test-positive and 30 PPD patch test-negative subjects. A defined volume of a marketed hair colouring product containing 1.8% PPD was applied in an open patch test to the retroauricular area. The grading method comprised the dermatologist's clinical evaluation and objective numerical scores. Allergic reactions were elicited in all PPD-positive subjects with a maximal intensity on Day 2; no allergic reactions were elicited in PPD-negative subjects. Increased severity of reactions by the dermatologist's clinical evaluation was correlated strongly with increasing numerical scores. The "skin sensitivity test" can be considered as an effective method to detect type IV hair dye allergy and as such, as an important factor in its secondary prevention.

Skin inflammation during contact hypersensitivity is mediated by early recruitment of CD8+ T cytotoxic 1 cells inducing keratinocyte apoptosis.

Contact hypersensitivity (CHS) is a T cell-mediated, Ag-specific skin inflammation induced by skin exposure to haptens in sensitized individuals. Th1/T cytotoxic 1 cells are effector cells of CHS, whereas Th2/T regulatory CD4(+) T cells have down-regulating properties. We have previously shown that CHS to 2,4-dinitrofluorobenzene is mediated by specific CD8(+) effector cells, whose cytolytic activity is mandatory for induction of skin inflammation. In this study, using immunohistochemistry and RT-PCR analysis, we show that CD8(+) T cells are rapidly recruited into the skin at the site of hapten challenge before the onset of clinical and histological signs of skin inflammation. This early CD8(+) T cell recruitment is concomitant with: 1) transient IFN-gamma mRNA expression suggesting local activation of effector cells; and 2) induction of keratinocyte (KC) apoptosis which gradually increased to a maximum at the peak of the CHS response. Alternatively, skin infiltration of CD4(+) T cells occurred later and coincided with the peak of the CHS reaction and the beginning of the resolution of skin inflammation. Mice deficient in CD8(+) T cells did not develop CHS, whereas mice deficient in CD4(+) T cells developed an enhanced inflammatory response with increased numbers of CD8(+) T cells recruited in the skin associated with massive KC apoptosis. These data show that CHS is due to the early and selective recruitment in the skin of CD8(+) T cytotoxic 1 effector cells responsible for KC apoptosis.

MHC class II-KO mice are resistant to the immunosuppressive effects of UV light.

Ultraviolet B light is responsible for the development of skin cancer through inhibition of cellular immune responses in the skin. Here, we addressed the question of the mechanisms involved in UVB-induced immune suppression. We used a model of antigen-specific skin inflammation, the contact hypersensitivity (CHS) reaction to DNFB, which is mediated by CD8+ effector T cells and down-regulated by CD4+ T cells. We show that UVB have opposite effects on CD4+ and CD8+ T cells. UVB irradiation reduced the number of activated CD8+ T cells in the lymphoid organs and impaired their functional activity. This resulted in deficient infiltration of IFN-gamma producing CD8+ T cells at challenged site and consequently in the inability to develop an antigen-specific CHS reaction. This effect is mediated by CD4+ suppressor cells, since in the absence of CD4+ T cells (MHC class II-KO mice and CD4+ T cell-depleted mice), UVB have no immunosuppressive effects. Indeed, UVB-irradiated CD4+ T cell-deficient mice have a normal frequency of IFN-gamma-producing hapten-specific CD8+ T cells in the lymphoid organs and develop a normal CHS reaction to DNFB. Thus, in the absence of CD4+ T cells, UVB do not alter the priming of MHC class I-restricted CD8+ effector T cells. Collectively, these data show that UVB-induced immune suppression is secondary to preferential activation of CD4+ suppressor T cells and not to deficient priming and expansion of the effector CD8+ T cell population. This may have important implications for the prevention of UV-induced skin cancers.

Age-related changes of the somatosensory evoked potentials in healthy children.

AIM: The aim of the study was to investigate the configuration and latency of the somatosensory evoked potentials (SEPs) in healthy children for the time from the neonatal period to adolescence. MATERIAL AND METHODS: SEPs were recorded in 67 healthy children--37 boys and 30 girls from 0 to 16 years of age by means of median nerve stimulation. The active electrode was placed above the contralateral parietal cortex on places C3' and C4' and the reference electrode--on Fpz. The filters were 10-1000 Hz and the frequency of the electric stimulus--3 Hz. RESULTS: The depression of the potential in the neonatal period is accounted for by the wide base and low amplitude of SEPs. The configuration of SEPs is identical with that of adult individuals after 3 years of age. The latencies of the waves P15, N20 and P25 decrease progressively with age and lengthen in the period from 9 to 16 years of age, with the increase of height. The interpeak latencies P15 - N20, N20 - P25 and P15 - P25 decrease with age, while the amplitude N20/P25 increase with age. We found significant variability in the amplitude of the potential, most pronounced in the neonatal period. It gradually decreases by 10-14 months of age and after that remains unchanged. We did not find any differences at stimulation between the left and the right hand. CONCLUSION: The age-related changes in SEPs reflect the trends of the development and the maturation of the neural pathways and their better myelinization.