An animal study on the bone behaviour of Ca–P-coated implants: influence of implant location

Four different implant materials were installed into the mandibular corner of goats to investigate the trabecular bone response in a mainly unloaded model. The implants were installed using a standardized technique and were left in situ for 12 weeks. One goat had to be sacrificed after surgery because of a broken rib; the other animals healed uneventfully. After sacrifice of the animals, the bone response to the uncoated and the three different Ca–P implants was evaluated histologically and histomorphometrically. Four sections of each implant were evaluated; two were located in the cortical and two in the trabecular bone. Of the 44 retrieved implants, 20 implants appeared to be installed partially in the mandibular canal, as clearly visible on the X-rays. These implants were not used in the histomorphometrical measurements. Histological evaluation showed that the trabecular and cortical bone reactions were similar; there was no significant difference in the percentage of bone contact nor in the amount of bone in contact with the implants. In conclusion this study showed that the mandibular corner is an unsatisfactory model for the installation of implants because of anatomical restrictions. Also, the experiment remained inconclusive about the influence of loading conditions on bone behaviour. Nevertheless, the histological results confirmed the bioactive properties of Ca–P coatings.     

Direct heating of drying air with natural gas in the preparation of milk powder

The question is considered whether in the production of milk powder direct heating of the drying air can be used as an alternative to indirect heating. Direct gas firing appears to result in substantial savings in the cost of energy and in capital expenditure. As compared with indirect heating, direct gas firing leads to the milk powder showing a slight increase in nitrate content (on average 8–14 mg/kg) and a marked increase in nitrite content (on average 0.4-3 mg/kg). This level of contamination is expected to diminish when a "low NO_x" burner is used. Whereas in preliminary research into the presence of volatile N-nitrosamines a level slightly above 1 μm N-nitrosodimethylamine (NDMA)/kg powder was found, more recent experiments showed a maximum of 0.3 g NDMA/kg. There seemed to be no significant relation between the nitrosamine content of the product and the method of heating the drying air.     

Analysis of the DNA Sequence of a 34 038 bp Region on the Left Arm of Yeast Chromosome XV

We report the DNA sequence of a 34 038 bp segment of Saccharomyces cerevisiae chromosome XV. Subsequent analysis revealed 20 open reading frames (ORFs) longer than 300 bp and two tRNA genes. Five ORFs correspond to genes previously identified in S. cerevisiae, including RPLA2, PRE6, MSE1, IFM1 and SCM2 (TAT2, TAP2, LTG3). Two putative proteins share considerable homology with other proteins in the current data libraries. ORF O2145 shows 41·2% identity with the glycophospholipid-anchored surface glycoprotein Gas1p of S. cerevisiae and ORF O2197 has 53·2% identity to chromosome segregation protein Dis3p of Schizosaccharomyces pombe. Accession Numbers for these sequences are provided in Table 1.©1997 John Wiley & Sons, Ltd.     

Effect of Extrusion Cooking on in Vitro Protein Digestibility of Sorghum

Extrusion variables including moisture (15 and 2.5%), temperature (50°, 125° and 200°C) and screw speed (50, 125 and 200 rpm) of two low tannin sorghum varieties extruded with 0, 2 and 4% calcium hydroxide were studied. Protein digestibility was determined by in vitro pepsin assay. Extrusion improved digestibility from 45.9 to 74.6% and 43.9 to 68.2% for the two varieties, respectively. Temperature was the key extrusion variable that influenced digestibility. Screw speed and moisture did not have significant effects. Alteration of pH before extrusion further improved digestibility.