Subchronic 3-month oral toxicity study of grape seed and grape skin extracts.

Meganatural brand grape seed extract (GSE) and grape skin extract (GSKE), containing proanthocyanidin (PAC) polyphenolic compounds, are intended for use in food as functional ingredients exhibiting antioxidant activity. Proanthocyanidins, as well as the minor constituent phenolic compounds in GSE and GSKE, are present naturally in many foods such as fruits, vegetables, chocolate, tea, etc., and on average people consume 460-1000 mg/day of these combined substances. Although humans have ingested PACs for centuries without reported adverse effects, the current toxicology literature contains relatively little formal evidence regarding their safety. Accordingly, as part of a program to investigate the safety of GSE and GSKE, these products were incorporated into chow and fed to rats for at least 3 months in a GLP-compliant subchronic toxicity study. Groups of CD (Sprague-Dawley) Crl:CD IGS BR rats (20 males and 20 females per group) were fed diets containing GSE at concentrations of 0, 0.63, 1.25 or 2.5% (w/w); GSKE was fed at 2.5% (w/w) only. Clinical observations were recorded and body weight and feed consumption measured throughout the study. After 1 month, blood was obtained from 10 rats/sex/group by retrobulbar puncture for interim measurement of clinical pathology. At the end of the study the rats were subjected to a full necropsy, aortic blood samples were collected for clinical pathology, selected organs were weighed and a complete list of tissues was preserved from all animals. Histologic examination was performed on all tissues from control and high-dose GSE and GSKE groups. There were no treatment-related changes that were considered to be of toxicologic significance. Therefore, a dietary concentration of 2.5% GSE or 2.5% GSKE was considered to be a no-observed-adverse effect level (NOAEL). This was equivalent to a time-weighted average dose over the course of the study of approximately 1.78 g/kg body weight/day GSE or GSKE in male rats and 2.15 g/kg body weight/day in female rats.

Inhibition of human O6-methylguanine-DNA methyltransferase by 5-methylcytosine.

The ability of cloned human O6-methylguanine-DNA methyltransferase to repair a methylated guanine in a CpG-containing sequence, i.e., island, was studied by using a synthetic double-stranded 20-mer oligonucleotide from codon 248 of the p53 gene and another designed sequence. The double-stranded oligonucleotides incorporating 5-methylcytosine (5mC) and O6-methylguanine (O6mG) in various combinations in a CpG site were 5' labeled with 32P and incubated with recombinant O6-methylguanine-DNA methyltransferase. The rate constant for O6-methylguanine-DNA methyltransferase repair of O6mG in this oligomer was always higher with the substrate which contained only the O6mG, as compared to the oligomer that included a 5mC adjacent in the 5'-position to the methylated guanine. The reduction in substrate activity ranged from 75% (modified p53 sequence) to 100% (in the designed oligomer). A 5mC opposite the O6mG reduced the rate slightly. These results suggest that O6-methylation of the guanine moiety at CpG islands may not be efficiently repaired when normal 5mC is present and this may contribute significantly to an increase in mutagenesis of p53 and like molecules.

Primary closure of pilonidal cystectomy.

A method of primary closure following excision of pilonidal cysts and sinus was used in 38 cases. The criteria for patient selection are described as is the technique and procedure. Special attention must be placed on the obliteration of all "dead spaces" to eliminate accumulation of serum and blood. The dressing is not changed for a minimum of eight days, and pressure must be maintained for that time to assure success. In all cases complete closure was obtained. The advantages of this technique over the open procedure is explained.