Nitrous oxide occupational exposure in conscious sedation procedures in dental ambulatories: a pilot retrospective observational study in an Italian pediatric hospital

BACKGROUND

Nitrous oxide has a proven clinical efficacy in conscious sedation. At certain environmental concentrations it may pose a health risk to chronically exposed healthcare workers. The present pilot study aims at evaluating the exposure to nitrous oxide of dental ambulatory personnel of a pediatric hospital.

METHODS

A descriptive study design was conducted in two phases: a bibliographic analysis on the environmental safety policies and a gas concentration analysis in the dental ambulatories of a pediatric hospital, detected every 6 months from December 2013 to February 2017 according to law provisions. The surveys were carried out using for gas analysis a photoacoustic spectrometer Innova-B&K "Multi-gas monitor model 1312" and Innova-B&K "Multi-sampler model 1309". The biological analysis and monitoring have been carried out on staff urine.

RESULTS

The analyses were performed during 11 dental outpatient sessions on pediatric patients. All the patients were submitted to the same dental procedures, conservative care and dental extractions. The pediatric patients were 47 (23 males, 24 females; age range 3-17 years; mean age 6,63, SD ± 2,69) for a mean of 4,27 (SD ± 1,49) per session., The mean environmental concentration of nitrous oxide during the sessions was 24.7 ppm (SD ±16,16). A correlation was found between urinary nitrous oxide concentration of dentists (Pearson's correlation 0.786; p = 0.007) and dental assistants urines (Pearson's correlation 0.918; p < 0.001) and environmental concentrations of nitrous oxide. Weak negative correlations were found between age and sex of patients and environmental concentrations of nitrous oxide. The mean values of the biological monitoring data referring to all the outpatient sessions are lower than the reference values foreseen in accordance to the regulations in force on nitrous oxide concentration.

CONCLUSIONS

The mean environmental concentration values recorded in our study are below the limit of 50 ppm considered as a reference point, a value lower than those reported in other similar surveys. The results of the present study provide a contribution to the need to implement technical standards, criteria and system requirements for the dental ambulatories, to date not yet completely defined, and cannot be assimilated to the ones established for the surgical rooms.

Morpho-Structural Investigations of Biomaterials for Biocidal Activity

A new wound dressing made of gelatin and Ag, was evaluated for the management of tissue reconstitution in rats. The gelatin–based dressing, with metabolic stimulation properties that favored the recovery of the skin was made of stiff sheets to supply the repairingtissue with mechanical support. The gelatin sheets enhanced the development of collagen fibers and subsequently cell proliferation at the level of stromal and vascular elements. A protocol based on the utilization of natural biomaterials in the presence of low concentrations of a biocidal was proposed which could control microbiocidal activities principally in burned and debilitated patients.

[Risk of non-coherent optical radiation in the operating room]

In this study, we evaluated the exposure of operating room personnel to non-coherent optical radiation by measuring the emission of blue light generated by operating lights. The values we obtained were largely below the exposure limit value of 100 W x m(-2) x sr(-1) provided by Legislative Decree no. 81/08 and European Directive 2006/25/EC, showing how workers can be exposed for longer than 8 hours without risk of acute health effects, confirming what was already said in literature. This work demonstrates, therefore, that the risk of acute nature of photochemical retinal damage, caused by exposure to blue light, is absent, if not exceeded the exposure limit values, on the basis of the current knowledge, however, respect for exposure level cannot protect against a possible retinal damage from chronic exposure, related to the total dose accumulated by the worker in the long-term.

[Occupational exposure to sevoflurane in pediatric operating rooms: the multi-point sampling method for risk assessment]

Several studies have shown that occupational exposure to anesthetic gases might be higher during pediatric surgery, probably due to the increased use of inhalational induction techniques. Our study aims to assess the level of exposure to sevoflurane in two rooms of pediatric surgery, using multi-point sampling method for environmental monitoring. The gas concentrations as well as its dispersion were measured in strategic points in the rooms for a total of 44 surgical interventions. Although the average of these concentrations has been rather low (1.32, SD +/- 1:55 ppm), the results obtained have documented a significant distribution kinetics difference inside the rooms as function of multiple factors among which there were the anesthetic technique used and the team involved. Therefore the method described allows to correctly analyze the spread of anesthetic gases and suggests a different risk stratification which may be dependent on the professional work.

Persistent ex vivo low number and functional in vitro recovery of circulating gammadelta T cells after removal of a cutaneous primary melanoma

We recently described gammadelta T cells alterations in patients with a cutaneous primary melanoma. To evaluate whether gammadelta T cells alterations persisted after melanoma removal, we performed a follow-up study comparing the number and function of gammadelta T lymphocytes from 19 subjects, 4 years after the removal of a cutaneous primary melanoma, with the data obtained in the same subjects before the surgical intervention and with control donors. The number of circulating gammadelta(+) T cells after melanoma removal was not recovered to the levels found in controls. gammadelta(+) T cells producing TNF-alpha or IFN-gamma were increased after melanoma removal in comparison with the same subjects before surgical intervention or with control donors. After in vitro culture, both the percentage and the expansion of gammadelta T cells were recovered to the values found in controls. In conclusion, the functional capacity of gammadelta T cells was in vitro recovered after melanoma removal, whereas their ex vivo number remained at lower levels than control donors.

Immunohistochemical study of apoptosis markers and involvement of chemokine CXCR4 in skin Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive cancer of the skin that mainly affects elderly patients. Because of its rarity, there is no established treatment or proven markers to guide therapy or prognosis. Immunohistochemical expression of apoptosis proteins is considered a useful marker of both malignancy and tumour progression. Apoptosis plays a fundamental role in skin homeostasis, and apoptotic cells have been detected in normal and diseased skin. Chemokines possess a wide range of biological activities and CXCR4 is expressed in some cancer cells, where it plays an efficient role in metastasis formation.

OBJECTIVE

To identify immunohistochemical parameters that can help clinicians select the most suitable therapy for skin MCC.

DESIGN

Antibodies against ki67, bcl-2, p53, survivin, p16 and CXCR4 were tested to assess the usefulness of these antigens as indices of proliferation potential and predictors of prognosis.

METHODS

Immunohistochemical detection of apoptosis inhibitors and CXCR4 was performed on tissue from 12 patients with primary MCC. After excision of the primary lesion, five survived and had no metastases, and seven experienced local recurrence or lymph node metastases.

RESULTS

Expression of ki67 and survivin was increased in patients with local recurrence or metastasis (retrospectively classified as 'poor prognosis') compared with those with a 'good prognosis', and bcl-2 expression was significantly greater (P=0.003). P53 and p16 immunostaining was moderate in both groups. A positive correlation was observed between survivin and mutant p53 in the poor prognosis group (r=0.593, P=0.033; regression coefficient). High values of p53 were measured in patients with high levels of survivin and vice versa. CXCR4 was not detected at all.

CONCLUSIONS

Our results show strong MCC cell apoptosis inhibition and a high cell proliferation capacity. The positive correlation between survivin and p53 may be a predictor of MCC spread via the lymphatic network. Absent CXCR4 expression may reflect a less aggressive form, with less efficient development of distant and non-organ-selective metastasis formation.

rhVEGF and experimental rat skin flaps: systemic or local administration and morphological characteristics

Skin flap survival is a significant problem in skin surgery; in particular, inadequate arterial or venous blood supply results in necrosis of the distalmost portion. The aim of this study was to evaluate the ability of Vascular Endothelial Growth Factor (VEGF) of modifying the morphological features of skin flaps. Bilateral epigastric skin flaps were raised in 16 Wistar male rats. The epigastric artery and vein of the left flaps were clamped and then injected with rhVEGF (8 rats) or saline (8 rats). The right flaps were not clamped and received rhVEGF or saline systemically. The rats were euthanized on the seventh day and flap skin samples collected. Tissue fragments were subject to immunohistochemical (rhVEGF, VEGFr, VIII factor, CD34 antibodies), ultrastructural and morphostructural investigations. The results showed that rhVEGF improved the condition of flaps and that systemic administration was effective in promoting the development of an adequate vascular network.

Comparative pharmacodynamics of keliximab and clenoliximab in transgenic mice bearing human CD4

Keliximab and clenoliximab are monkey/human chimeric CD4 monoclonal antibodies (mAbs) of the IgG1 and IgG4 isotypes, respectively. The pharmacokinetics (PK) and pharmacodynamics (PD) of these mAbs were evaluated in transgenic mice bearing human CD4 molecules on their T cells after a single i.v. administration at three dose levels (5-125 mg/kg). The PK of keliximab and clenoliximab were similar, dose-dependent, and adequately described by a two-compartment model with saturable elimination from both compartments. The enumeration of circulating CD4(+) T cells and density of CD4 on their surface were determined as the PD effects. An indirect response model was proposed to characterize the PD effects. With the increase in mAb dose, the maximum intensity (R(max)) of PD effects was increased, and the time to reach R(max) shifted to later times. At all three dose levels, keliximab caused a relatively rapid decline in the number of circulating CD4(+) T cells, which then recovered gradually. In contrast, clenoliximab at the lowest dose (5 mg/kg) did not produce a significant effect on CD4(+) T cell counts compared with the placebo group. At high doses, clenoliximab caused a significant decrease in the number of CD4(+) T cells. Keliximab appeared to be more potent and efficient in depleting CD4(+) T cells. Both mAbs produced similar down-modulation of CD4 at corresponding dose levels. The findings of this study are consistent with the results of a recent clinical trial that emphasize the importance of this transgenic mouse model for evaluating PK/PD to support clinical development of anti-human CD4 mAbs.

Advances in the understanding of malignant transformation of keratinocytes: an immunohistochemical study

AIM

We set out to investigate the interactions between malignant transformation of keratinocytes, presence of oncoproteins and immunosurveillance in squamous cell carcinoma (SCC) and in a preneoplastic lesion, actinic keratosis (AK).

METHODS

Samples of SCC, AK and normal skin (NS) were subjected to quantitative analysis using the following antibodies: anti-p53, Ki67, OKT6, OK-DR, B7/BB1, anti-CD54, anti-CD11, OKT3, OKT4, OKT8; positivity for ras-p21, EGFr and bcl-2 was evaluated by semiquantitative analysis.

RESULTS

Oncoprotein alterations and increased keratinocyte proliferative activity were observed both in AK and SCC. The number of Langerhans cells (CD1a+ cells) was similar in the two lesions but lower in SCC compared to AK. The proportion of CD1a(+)-B7/BB1+ cells was slightly higher in AK and SCC than in NS. The Langerhans cells expressed the HLA-DR antigen in all groups. Values were highest in AK and NS, and quite low in SCC. Cytotoxic T lymphocytes were more numerous in SCC than in AK and NS. Interestingly, the total CD4/CD8 ratio was much lower in SCC than in AK and NS, which indicates an increase in the CD8+ subpopulation in samples of SCC. In the epithelia of SCC samples there were a considerable number of B7/BB1+ keratinocytes.

CONCLUSIONS

We suggest that alterations in the immunodefence mechanisms have an important role in the transformation of AK into SCC, and that these changes affect not only lymphocytes, but also professional (i.e., Langerhans cells) and non-professional (i.e., keratinocytes) antigen presenting cells.

An experimental pilot study of tacalcitol activities during modulation of parakeratotic skin features

Establishing guidelines and experimental models preclinical and clinical evaluations of new agents for treatment, and/or prevention of human diseases has become a task of crucial importance. Psoriasis is such one disease holding great interest for dermatology owing to its high rate of incidence and complexity of treatment. However the absence of psoriatic lesions in animals and the inability to induce them, calls for experimental techniques both in vitro and in vivo. The purpose of this study was to evaluate experimentally the effects of tacalcitol on cell proliferation and differentiation process. Thereafter a human pilot study on psoriatic patients has been developed.

Structural features of latex gloves in dental practice

The aim of this study was to define from a morpho-structural point of view, using scanning electron microscopy, the features of various types of disposable latex gloves commonly used in Italian dental practice (Biogel D, Trend, Pagni, J&J, Latechnics, Pehasoft, Bantex). None of the brands examined was free from morphological flaws; however, while in some of these only slight depressions were found (Biogel D, Trend), in others (Latechnics, Bantex) there was a marked lack of homogeneity in the latex structure or real holes (Pehasoft). This study emphasizes the current difficulties faced by dentists in the search for safe working conditions.