强力霉素凝胶治疗大鼠口腔溃疡的实验研究

目的研究强力霉素对口腔溃疡的治疗作用,为临床用药提供指导。方法采用60%水醋酸酸蚀SD大鼠口腔颊黏膜建立大鼠溃疡模型。取36只造模成功大鼠随机分为3组,每组12只,分别给予高低剂量强力霉素及空白凝胶作局部治疗,分别于用药第2天、第4天、第6天每组处死4只大鼠,经过切取标本,石蜡包埋,制片,HE染色、麦氏染色和免疫组化染色后,于光镜下进行观察。结果用药后,强力霉素高低剂量组较对照组炎性渗出明显减少,充血情况明显减轻,胶原纤维降解、MMP-9的表达明显减少,溃疡愈合更快。结论强力霉素可能是通过抑制MMP-9的表达,减少胶原纤维的降解,促进口腔溃疡愈合。     

Subantimicrobial dose doxycycline as adjunctive treatment for periodontitis. A review

BACKGROUND: Subantimicrobial dose doxycycline (SDD--20 mg doxycycline twice daily) is indicated as an adjunctive treatment for periodontitis. Doxycycline downregulates the activity of matrix metalloproteinases (MMPs), key destructive enzymes in periodontal disease. Current understanding of periodontal pathogenesis suggests that MMPs play a major role in the destruction of periodontal tissues, leading to the clinical signs of periodontitis. Research supports that downregulation of MMPs by SDD confers benefit to patients with periodontitis. METHOD: We review the clinical, microbiological and safety data relating to the use of SDD in patients with periodontitis, and consider the historical events that led to the development of adjunctive SDD as a treatment for periodontitis. RESULTS: Studies have shown that SDD, when prescribed as an adjunct to scaling and root planing (SRP), results in statistically and clinically significant gains in clinical attachment levels and reductions in probing depths over and above those that are achieved by SRP alone. SRP must be thorough and performed to the highest standard to maximise the benefits of adjunctive SDD. SDD does not result in antibacterial effects, or lead to the development of resistant strains or the acquisition of multiantibiotic resistance. The frequency of adverse events is low, and does not differ significantly from placebo. CONCLUSIONS: Adjunctive SDD confers clinical benefit to patients with periodontitis. A comprehensive treatment strategy is suggested, involving patient education and motivation, reduction of the bacterial burden by SRP, host response modulation with SDD, and periodontal risk factor modification.     

Current topical and systemic approaches to treatment of rosacea

Rosacea is a common, often overlooked, chronic facial dermatosis characterized by intermittent periods of exacerbation and remission. Clinical subtypes and grading of the disease have been defined in the literature. On the basis of a genetic predisposition, there are several intrinsic and extrinsic factors possibly correlating with the phenotypic expression of the disease. Although rosacea cannot be cured, there are several recommended treatment strategies appropriate to control the corresponding symptoms/signs. In addition to adequate skin care, these include topical and systemic medications particularly suitable for the papulopustular subtype of rosacea with moderate to severe intensity. The most commonly used and most established therapeutic regimens are topical metronidazole and topical azelaic acid as well as oral doxycycline. Conventionally, 100–200 mg per day have been used. Today also a controlled release formulation is available, delivering 40 mg per day using non-antibiotic, anti-inflammatory activities of the drug. Anti-inflammatory dose doxycycline in particular allows for a safe and effective short- and long-term therapy of rosacea. Topical metronidazole and topical azelaic acid also appear to be safe and effective for short-term use. There are indications that a combined therapy of anti-inflammatory dose doxycycline and topical metronidazole could possibly have synergy effects. Further interesting therapy options for the short- and long-term therapy of rosacea could be low-dose minocycline and isotretinoin; however, too little data are available with regard to the effectiveness, safety, optimal dosage and appropriate length of treatment for these medications to draw final conclusions.

Conflicts of interest

None declared.     

Doxycycline Inhibition of a Pseudotyped Virus Transduction Does Not Translate to Inhibition of SARS-CoV-2 Infectivity

The rapid spread of the pandemic caused by the SARS-CoV-2 virus has created an unusual situation, with rapid searches for compounds to interfere with the biological processes exploited by the virus. Doxycycline, with its pleiotropic effects, including anti-viral activity, has been proposed as a therapeutic candidate for COVID-19 and about twenty clinical trials have started since the beginning of the pandemic. To gain information on the activity of doxycycline against SARS-CoV-2 infection and clarify some of the conflicting clinical data published, we designed in vitro binding tests and infection studies with a pseudotyped virus expressing the spike protein, as well as a clinically isolated SARS-CoV-2 strain. Doxycycline inhibited the transduction of the pseudotyped virus in Vero E6 and HEK-293 T cells stably expressing human receptor angiotensin-converting enzyme 2 but did not affect the entry and replication of SARS-CoV-2. Although this conclusion is apparently disappointing, it is paradigmatic of an experimental approach aimed at developing an integrated multidisciplinary platform which can shed light on the mechanisms of action of potential anti-COVID-19 compounds. To avoid wasting precious time and resources, we believe very stringent experimental criteria are needed in the preclinical phase, including infectivity studies with clinically isolated SARS-CoV-2, before moving on to (futile) clinical trials.     

Prurigo pigmentosa

A 22-year-old Chinese woman presented with a 5-year history of an intensely pruritic eruption on her posterior neck, mid back and sacrum leaving reticulate pigmentation. The diagnosis of prurigo pigmentosa was made on the basis of the clinico-histological features and a response to minocycline. Although prurigo pigmentosa is uncommon, it has characteristic clinical and histological features. Early diagnosis and appropriate treatment result in a rapid response and prevents a progression of pigmentation.     

Pruritic eruption with reticular pigmentation: confluent and reticulate papillomatosis

A 28-year-old man presented with a 2-year history of a pruritic eruption on his neck, chest, back, axillae, and antecubital and pubic areas. The patient had been previously treated with topical and systemic antifungal therapy for a long time, but showed no response. Examination revealed the typical clinical and histological features of confluent and reticulate papillomatosis. The patient responded well to oral doxycycline.