DNA methyltransferase activities have been partially purified from unfertilized eggs and blastula nuclei of sea urchin embryos. Comparative studies, using different DNAs as substrates, show that the two preparations are most active on hemimethylated and single-strand DNA, but they methylate, though at a lower rate, also on double-strand DNA. The two activities show distinctive efficiencies in methylating plasmid DNAs and marked differences in the rate of methyl transfer to DNAs in different structural states: linear, relaxed, or supercoiled. The ratio of the apparent specific activity of the two preparations depends on the particular DNA used as substrate and its structure. Methylation analysis of the restriction fragments of methylated plasmid DNAs shows a linear correlation between introduced methyl groups and the percent of CpG of each particular fragment, indicating that methylation is substantially random and sequence is less relevant than conformation in determining enzyme efficiency. The data do not permit us to decide if the two activities are different enzymes or the same enzyme with different modulating factors.

Animals↗

PubMedDate not supplied

[Video laparoscopic appendectomy. Our experience].

OBJECTIVE: Personal experience with the use of VL in the treatment of acute appendicitis (AA) is reported. The main advantage of this method is its high diagnostic reliability. SETTING: Chirurgia Generale I. Dipartimento di Discipline Chirurgiche e Anatomiche. Policlinico Università Palermo. SUBJECTS: The VL method has been used in 36 patients with diagnosis of suspect acute appendicitis. INTERVENTIONS: In the cases in which the diagnosis has been confirmed, a VL appendectomy with endoabdominal technique according to Semm has been performed in 23 cases, and an assisted VL appendectomy, trough a minimal and guided laparotomy, in 8 cases. In order to avoid vascular and visceral injuries, an "open" laparoscopy technique is always used. RESULTS: The diagnosis has been confirmed in 31 cases, 21 women and 10 men. The diagnosis has not been confirmed in 5 cases, a man of 74 years with sigmoidal diverticulitis and 4 women with terminal ileitis in a case, torsion of right ovarian cyst in another and, finally, pelvic inflammatory disease in 2. CONCLUSIONS: From this brief experience it is evident the diagnostic advantage of VL particularly in the female and in elderly patients. Other advantages of this method are the excellent aesthetic result, light postoperative pain, the rapid functional resumption, the small impact of adherences, wound infection, and incisional hernia, and the lower cost, when staplers are not used. The disadvantages are the extension of the operative time, using the "open" laparoscopy technique, and the difficulty to find Meckel diverticulum.

Acute Disease↗