Experimental doxycycline overdose in rats causes cardiomyopathy

All reports of doxycycline‐induced cardiomyopathy to date have been limited to accidental oral poisoning in calves. Therefore, the current study investigated the cardiomyotoxic effect of experimental doxycycline overdose in rats as a toxicity model which could be monitored using histopathological and biochemical assays. A total of 38‐week‐old male Wistar rats were divided into three groups consisting of 10 each. The first group was an untreated control group (D₀), and the second group (D₅) received doxycycline hyclate 25 mg/kg intragastrically twice daily (8 AM and 8 PM), which is 5‐fold higher than the standard dose. The third group (D₁₀) received 50 mg/kg intragastrically twice daily (8 AM and 8 PM), which is 10‐fold higher than the standard dose. The dose continued for 10 consecutive days and revealed that the doxycycline toxicity was dose dependent. Mortality was recorded in the D₁₀ group only (30%). The D₅ rats exhibited minimal skeletal muscle injury and slight but significant increases in the skeletal muscle damage indicators creatine kinase (CK) and aspartate aminotransferase (AST) compared to controls. The cardiac muscle of the D₅ rats was histologically normal, and the D₅ rats also exhibited normal levels of troponin I (cTnI), an indicator of cardiac muscle damage. In contrast, the D₁₀ rats displayed cardiomyopathy, as well as significant increases in the muscle enzymes alanine aminotransferase (ALT), AST and CK and the cardiac damage indicator cTnI compared to control and D₅ groups. Pulmonary lesions were observed in the D₁₀ rats, primarily cardiac lesion‐related alveolar heart failure cells. Thus the present study is the first to demonstrate that oral doxycycline poisoning (10 times the therapeutic dose)‐induced cardiomyopathy is not limited to calves and could occur without any predisposing factors.     

Activation of central GABAB receptors offsets the cyclosporine counteraction of endotoxic cardiovascular outcomes in conscious rats

We have previously shown that cyclosporine (CSA) counteracts cardiovascular manifestations induced by endotoxemia (lipopolysaccharide, LPS) such as hypotension and cardiac autonomic dysfunction in conscious rats. In this study, we investigated whether the facilitation of central γ‐amino butyric acid (GABA) neurotransmission blunts these favorable influences of CSA. The LPS‐CSA interaction was determined in the absence and presence of drugs that activate GABA_A or GABA_B receptors or elevate synaptic GABA levels in the central nervous system. The consequent i.v. administration of CSA (10 mg/kg) blunted the LPS‐evoked hypotension, tachycardia, and reductions in time‐ and frequency‐domain indices of heart rate variability (measures of cardiac autonomic control) evoked by LPS (10 mg/kg i.v.). The ability of CSA to reverse the LPS effects disappeared in rats treated intracisternally (i.c.) with baclofen (selective GABA_B agonist, 2 μg/rat) but not muscimol (selective GABA_A agonist, 1 μg/rat), indicating a preferential compromising action for central GABA_B receptors on the advantageous effects of CSA. Moreover, the improvement by CSA of LPS‐evoked cardiovascular derangements was also eliminated after concurrent i.c. administration of vigabatrin (GABA transaminase inhibitor, 200 μg/rat) or tiagabine (GABA reuptake inhibitor, 100 μg/rat). These results demonstrate that the activation of central GABA_B receptors either directly via baclofen or indirectly following interventions that boost GABA levels in central synapses counterbalances the rectifying action of CSA on endotoxemia.     

Topical photodynamic therapy using transfersomal aluminum phthalocyanine tetrasulfonate: in vitro and in vivo study

The efficacy of transfersomes (flexible liposomes) as a novel technique for topical delivery of the hydrophilic tetra-anionic photodynamic sensitizer aluminum (III) phthalocyanine tetrasulfonate (AlPcS4) was investigated, on mammalian fibroblasts and on Balb/c mice dorsal skin. AlPcS4 was loaded in transfersomes composed of phosphatidylcholine/sodium deoxycholate (5:1, 10:1, and 15:1?w/w, ratios), resulting in 110-, 160-, and 200-nm mean size vesicles with encapsulation efficiencies of 16, 25, and 30 %, respectively. In vitro studies on baby hamster kidney-21 fibroblasts revealed twofold enhancement of the photocytotoxicity of AlPcS4 loaded in transfersomes (Trans-AlPcS4), compared to free AlPcS4 dissolved in culture medium. The photocytotoxicity of Trans-AlPcS4 was less dependent on the incubation time with cells, compared to free AlPcS4. Topical application on the dorsal skin of Balb/c mice revealed that both free AlPcS4 and Trans-AlPcS4 exhibited evident photosensitization towards mice skin, but acquiring different regions of skin.     

Effect of low-level laser therapy (LLLT) on orthodontic tooth movement

The aim of this study is to evaluate the effects of low-level laser therapy (LLLT) on (1) the velocity of orthodontic tooth movement and (2) the nitric oxide levels in gingival crevicular fluid (GCF) during orthodontic treatment. The sample consisted of 20 patients (14 girls, six boys) whose maxillary first premolars were extracted and canines distalized. A gallium-aluminum-arsenide (Ga-Al-As) diode laser was applied on the day 0, and the 3rd, 7th, 14th, 21st, and 28th days when the retraction of the maxillary lateral incisors was initiated. The right maxillary lateral incisors composed the study group (the laser group), whereas the left maxillary lateral incisors served as the control. The teeth in the laser group received a total of ten doses of laser application: five doses from the buccal and five doses from the palatal side (two cervical, one middle, two apical) with an output power of 20 mW and a dose of 0.71 J /cm². Gingival crevicular fluid samples were obtained on the above-mentioned days, and the nitric oxide levels were analyzed. Bonferroni and repeated measures variant analysis tests were used for statistical analysis with the significance level set at p ≤ 0.05. The application of low-level laser therapy accelerated orthodontic tooth movement significantly; there were no statistically significant changes in the nitric oxide levels of the gingival crevicular fluid during orthodontic treatment.     

Posterior polar cataract: A review

Posterior polar cataract is a rare form of congenital cataract. It is usually inherited as an autosomal dominant disease, yet it can be sporadic. Five genes have been attributed to the formation of this disease. It is highly associated with complications during surgery, such as posterior capsule rupture and nucleus drop. The reason for this high complication rate is the strong adherence of the opacity to the weak posterior capsule. Different surgical strategies were described for the handling of this challenging entity, most of which emphasized the need for gentle maneuvering in dealing with these cases. It has a unique clinical appearance that should not be missed in order to anticipate, avoid, and minimize the impact of the complications associated with it.     

Computed tomography of the orbit – A review and an update

Computed tomography (CT) and magnetic resonance imaging (MRI) of the orbit have been competing for the hearts and minds of health care providers for well over 2 decades. While several drawbacks pertaining to CT have been outlined since the introduction of MRI, CT remains the standard diagnostic test for evaluating cross-sectional, 2 or 3-dimensional images of the body.