Scattered UV irradiation during VISX excimer laser keratorefractive surgery

PURPOSE: To evaluate the potential occupational health hazards associated with scattered ultraviolet (UV) radiation during photorefractive keratectomy (PRK) using the VISX Star S3 excimer laser. SETTING: The Laser Vision Center, National Naval Medical Center, Bethesda, Maryland, USA. METHODS: Intraoperative radiometric measurements were made with the Ophir Power/Energy Meter (LaserStar Model PD-10 with silicon detector) during PRK treatments as well as during required calibration procedures at a distance of 20.3 cm from the left cornea. These measurements were evaluated using a worst-case scenario for exposure, and then compared with the American Conference of Governmental Industrial Hygeinists (ACGIH) Threshold Value Limits (TVL) to perform a risk/hazard analysis. RESULTS: During the PRK procedures, the highest measured value was 248.4 nJ/pulse. During the calibration procedures, the highest measured UV scattered radiation level was 149.6 nJ/pulse. The maximum treatment time was 52 seconds. Using a worst-case scenario in which all treatments used the maximum power and time, the total energy per eye treated was 0.132 mJ/cm2 and the total UV radiation at close range (80 cm from the treated eye) was 0.0085 mJ/cm2. With a workload of 20 patients, the total occupational exposure at 80 cm to actinic UV radiation in an 8-hour period would be 0.425 mJ/cm2. CONCLUSIONS: The scattered actinic UV laser radiation from the VISX Star S3 excimer laser did not exceed occupational exposure limits during a busy 8-hour workday, provided that operating room personnel were at least 80 cm from the treated eye. While the use of protective eyewear is always prudent, this study demonstrates that the trace amounts of scattered laser emissions produced by this laser do not pose a serious health risk even without the use of protective eyewear.     

Doxycycline-coated sutures improve the suture-holding capacity of the rat Achilles tendon

Background There is evidence of high matrix metalloproteinase (MMP) activity around sutures inserted into tendons. This probably results in tissue breakdown, allowing the suture to cut through the tendon, and thus contributes to repair-site elongation and gap formation. We therefore hypothesized that treatment with the MMP inhibitor doxycycline would improve the sutureholding capacity of tendon.

Animals, methods and results In the first sub-study, rats received a suture in the Achilles tendon. One group was treated with systemic doxycycline and the other received no treatment. At 3, 5, and 7 days, suture-holding capacity was measured mechanically. The pull-out force and energy were reduced in all tendons, at 3 days compared to freshly inserted sutures, but no further reduction was detected at later time points. Doxycycline- treated tendons showed improved suture-holding capacity as measured by higher energy uptake than in untreated tendons. Force at failure showed a trend towards improvement. The effect was most evident on day 3. In the second sub-study, sutures were coated with doxycycline. At 3 days, local doxycycline treatment caused improved suture-holding capacity—as measured by higher force at failure and higher energy uptake.

Interpretation We provide proof of a novel treatment principle. MMP inhibitor-coated sutures improve suture-holding capacity during early repair of collagenous tissues.     

Separation of binding affinity and intrinsic activity of the potent mu-opioid 14-methoxymetopon

Receptor binding studies of 5,14-O-dimethyloxymorphone (14-methoxymetopon) in brain membranes have established its high affinity for mu-binding sites, but its analgesic potency far exceeds the modest increase in binding affinity relative to other opioids. The current study has established the selectivity of [(3)H]14-methoxymetopon for mu sites in calf striatal membranes and for a number of full-length splice variants of the cloned murine mu-opioid receptor 1 (mMOR-1) in transfected cell lines. The binding affinity of [(3)H]14-methoxymetopon for the variants expressed in Chinese hamster ovary cells was quite high, with K(D) values around 0.2 nM for all of the variants with the exception of mMOR-1F (K(D) of 1.2 nM). The affinity for most of the expressed variants was greater than that seen in the brain membranes (K(D) of 0.99 nM). Functionally, in guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding assays with the MOR-1 variants, 14-methoxymetopon and the mu-opioid peptide [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) showed similar efficacies, as determined by maximal stimulation, but 14-methoxymetopon was up to 65-fold more potent than DAMGO. The greatest difference was seen with mMOR-1E and the least with mMOR-1C, which displayed only a 10-fold difference. These potency differences in the stimulation of [(35)S]GTPgammaS binding far exceeded the differences in binding affinity. The differences between 14-methoxymetopon and DAMGO remained after normalizing the potency shifts based upon receptor binding affinities and varied from 1.2-fold with mMOR-1C to 21-fold for mMOR-1 and 42-fold with mMOR-1F. Thus, 14-methoxymetopon is a potent agonist against all of the mMOR-1 splice variants, but its potency ranged widely despite similar binding affinities for most of the variants and may give insight into its unusual pharmacological profile.     

(125)I]orphanin FQ/nociceptin binding in Raji cells.

Western blots using an antibody which recognizes the orphanin FQ/nociceptin (OFQ/N) receptor reveals a band at approximately 69 kD in several cell lines, including the Raji human B cell lymphoma cell line. RT-PCR confirms the presence of this receptor in the Raji cells. Binding studies revealed a high affinity [(125)I][Tyr(14)]OFQ/N site in the Raji cells. The affinity of [(125)I][Tyr(14)]OFQ/N in the Raji cells (K(D) 68.4 pM) was similar to that in the transfected receptor (K(D) 36.7 pM). Its selectivity profile also was quite similar. OFQ/N competed binding quite potently (K(i) 65 pM), as did [Tyr(14)]OFQ/N (K(i) 33 pM). Traditional opioids displayed no appreciable affinity for the binding at any concentration examined, with the exception of naloxone benzoylhydrazone, which had only a very modest affinity. The receptors in the Raji cells were functionally active. OFQ/N inhibited forskolin-stimulated cyclase by 72% with an IC(50) value of approximately 1 nM.     

Q-switched ruby laser is safe and effective in treating primary gingival hyperpigmentation

Background

Physiologic gingival hyperpigmentation (PGH) is a benign condition that results from increased melanin production and is prevalent among darker skin individuals. Although the use of lasers for PGH has gained popularity in recent years, the lasers being used are mostly ablative, and act through a non-selective tissue damage mechanism.

Aims

The objective of this study was to evaluate the use of a non-ablative 694-nm Q-switched ruby laser (QSRL) for the depigmentation of PGH.

Methods

A retrospective single-center study of patients diagnosed with PGH and treated with a QSRL Between March 2019 and November 2020.

Results

Four patients were treated with QSRL for 1–3 sessions, until complete depigmentation was achieved. The average follow-up was 11 months (range 7–18 months) with no patient exhibiting re-pigmentation. Adverse events included mild local tenderness and transient erosions in two patients.

Conclusion

The 694-nm QSRL is a novel and promising safe and effective method for treating PGH with the advantages of being a non-ablative modality that minimizes tissue damage and optimizes the outcome.     

Renal agenesis: A meta-analysis of its prevalence and clinical characteristics based on 15 641 184 patients

Our objective was to analyse the newest relevant data on worldwide prevalence and associated symptoms of renal agenesis (RA). This meta-analysis builds on previous systematic reviews to include bilateral RA, its symptoms and data on gender, unilateral RA and anomaly location prevalence. Review of available data included records in English and other languages from PubMed, Embase, ScienceDirect, Web of Science, SciELO, BIOSIS, Current Content Connect Korean Journal Database and Russian Citation Index and Google. A total of 15 641 184 patients were analysed in relation to the prevalence of RA. The pooled prevalence of RA was 0.03% (95% CI: 0.03%–0.04%). Based on 500 subjects, a pooled prevalence of 47.96% (95% CI: 31.55%–64.58%) for unilateral and 52.04% (95% CI: 35.42%–68.45%) for bilateral RA has been set. Our study presents the newest generalized findings on bilateral RA. There appears to be universal disease and symptom prevalence with minor differences between world regions, although quality of future observational research should include genomic data. This will provide even further insight into the prognosis of various renal anomalies and their etiologies.