Platelet-rich fibrin (PRF) gel modified by a carbodiimide crosslinker for tissue regeneration

Platelet-rich fibrin (PRF) as a rich source of effective growth factors has been used as a scaffold in tissue regeneration. It is known that PRF exhibits rapid degradability against enzymes, which should be decreased using crosslinking agents to reduce the release rate of growth factors and increase the effectiveness of tissue regeneration. In this study, a carbodiimide crosslinker with different concentrations (0.01%, 0.05%, 1%, and 2%) was used to modify and improve the properties of PRF gel. The crosslinked gels were evaluated with analyses such as SEM, swelling, degradability, mechanical strength, release test, cytotoxicity, and cell adhesion. The results showed that with increasing crosslinker concentration, the morphology of the fiber structure changes drastically, the swelling rate decreases from 300% (control) to 160% for the crosslinked gel, the degradation time for the control sample increases from 8 days to more than two weeks for the crosslinked gel, and the Young''s modulus increases from 0.15 MPa (control) to 0.61 MPa for the crosslinked samples. Growth factors also showed lower release with increasing crosslinking ratio. Cytotoxicity assays demonstrated that by increasing the crosslinker concentration to 1% w/v, no cytotoxicity was observed. Cellular studies with DAPI staining showed that the cells penetrated well into the gels and were well distributed, especially in gels with lower crosslinker concentrations. In addition, the modified PRF gel can be used as a scaffold for tissue regeneration.

1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) as a crosslinker can improve the physical and mechanical properties of PRF gel by forming covalent bonds.     

Septicaemia and meningitis with campylobacter fetus subspecies intestinalis

Summary Two cases of infection with Campylobacter fetus subspecies intestinalis are reported. In a 46-year-old farmer the development of septicaemic campylobacteriosis with acute gastroenterocolitis was favoured by malnutrition due to chronic alcoholism. After treatment with erythromycin the patient recovered completely. The second patient, a 40-year-old worker with meningitis, recovered after combined streptomycin-erytromycin therapy. In both patients antibiodies against homologous and reference strains of Campylobycter fetus subspecies intestinalis, serotype 1 (Mitscherlich) were demonstrated in titres ranging from 1 : 16 to 1 : 64 by type the complement-fixation test.

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Sepsis und Meningitis durch Campylobacter fetus Subspezies intestinalis

Zusammenfassung Zwei Fälle von Campylobacter fetus-Infektion mit Sepsis und Meningitis wurden beobachtet. Bei einem 46jährigen Bauern wurde eine septische Campylobacteriosis durch extreme Mangelernährung infolge von chronischem Alkoholismus begünstigt. Die Therapie mit Erythromycin war erfolgreich. Der andere Patient war ein 40jähriger Arbeiter mit Meningitis; auch dieser hat nach einer kombinierten Erythromycin- und Streptomycinkur das Krankenhaus gesund verlassen. Das Serumantikörpertiter war 1 : 16 bis 1 :64 in der Komplementbindungsreaktion gegen Homologe und Referenzstämme der Campylobacter fetus subspecies intestinalis serotype I (Mitscherlich).

     

Double-blind crossover randomized trial of intravenously administered verapamil. Its use for atrial fibrillation and flutter following open heart surgery

Fourteen patients with onset of atrial fibrillation (11) or flutter (three) and ventricular rate over 120 beats per minute following cardiac surgery were treated with intravenous (IV) doses of verapamil hydrochloride or placebo in a double-blind crossover protocol. Patients with poor left ventricular function, hypotension, atrioventricular block, and taking beta-blockers and disopyramide were excluded. The dosages were 0.075 mg/kg and 0.15 mg/kg given 15 minutes apart, with termination of study on achieving an end point (conversion to sinus rhythm or slowing of ventricular rate to below 100 beats per minute). None reached the end point with placebo but all with verapamil. Baseline ventricular rate was 144 +/- 20 beats per minute, after placebo 143 +/- 16 beats per minute, and after verapamil 89 +/- 7 beats per minute (mean +/- SD). Thus, IV verapamil briefly slows the ventricular rate of atrial tachyarrhythmias following cardiac surgery.     

Are seizures more frequent in asthmatic children?

Asthma and epilepsy have been suspected to be related to each other for a long time. To determine the frequency of seizures occurring in all asthmatic children referred to the teaching hospitals affiliated to Tehran University of Medical Sciences (TUMS) for two consecutive years, we conducted the following study. 16 out of 202 cases had previous history of non-febrile seizures (7.9%). Five patients (2.5%) had only a single seizure, and the remaining (5.4%) had recurrent attacks. All cases had generalized tonic-clonic type of seizures. One of the cases had a prolonged seizure (status epilepticus) lasting for more than 30 minutes. We concluded that the occurrence of seizure in our asthmatic patients was far more frequent than that in the general population.     

Oriented nanofibrous silk as a natural scaffold for ocular epithelial regeneration

The aim of this study was to develop nanofibrous silk substrates for limbal stem cell expansion that can serve as a potential alternative substrate to replace human amniotic membrane. The human limbal stem cell was used to evaluate the biocompatibility of substrates (random and oriented nanofibrous mats, and human amniotic membrane) based on their phenotypic profile, viability, proliferation, and attachment ability. Biocompatibility results indicated that all substrates were highly biocompatible, as limbal stem cells could favorably attach and proliferate on the nanofibrous surfaces. Microscopic figures showed that the human limbal stem cells were firmly anchored to the substrates and were able to retain a normal corneal stem cell phenotype. Microscopic analyses illustrated that cells infiltrated the nanofibers and successfully formed a three-dimensional corneal epithelium, which was viable for 15 days. Immunocytochemistry and real-time PCR results revealed no change in the expression profile of limbal stem cells grown on nanofibrous substrates when compared to those grown on human amniotic membrane. In addition, electrospun nanofibrous silk substrates especially oriented mat provides not only a milieu supporting limbal stem cells expansion, but also serve as a useful alternative carrier for ocular surface tissue engineering and could be used as an alternative substrate to amniotic membrane.