Nanosecond fluctuations of the molecular backbone of collagen in hard and soft tissues: a carbon-13 nuclear magnetic resonance relaxation study

We have determined the amplitude of nanosecond fluctuations of the collagen azimuthal orientation in intact tissues and reconstituted fibers from an analysis of 13C NMR relaxation data. We have labeled intact rat calvaria and tibia collagen (mineralized and cross-linked), intact rat tail tendon and demineralized bone collagen (cross-linked), and reconstituted lathyritic (non-cross-linked) chick calvaria collagen with [2-13C]glycine. This label was chosen because one-third of the amino acid residues in collagen are glycine and because the 1H-13C dipolar coupling is the dominant relaxation mechanism. Spin-lattice relaxation times (T1) and nuclear Overhauser enhancements were measured at 15.09 and 62.98 MHz at 22 and -35 degrees C. The measured NMR parameters have been analyzed by using a dynamic model in which the azimuthal orientation of the molecule fluctuates as a consequence of reorientation about the axis of the triple helix. We have shown that if root mean square fluctuations in the azimuthal orientations are small, gamma rms much less than 1 rad, the correlation function decays with a single correlation time tau and T1 depends only upon tau and gamma rms and not the detailed model of motion. Our analysis shows that, at 22 degrees C, tau is in the 1-5-ns range for all samples and gamma rms is 10 degrees, 9 degrees, and 5.5 degrees for the non-cross-linked, cross-linked, and mineralized samples, respectively. At -35 degrees C, gamma rms is less than 3 degrees for all samples. These results show that mineral and low temperature significantly restrict the amplitude of nanosecond motions of the collagen backbone.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Diagnosis of Pancreatic Degenerative Atrophy in Dogs – a Practical Method

A convenient method was developed to diagnose pancreatic degenerative atrophy (PDA) in small animal practice based on the observations, that feeding crude soybean increases faecal protease activity in dogs with normal pancreatic function, while PDA-dogs remain completely negative in faecal protease activity. When PDA is suspected, 1 or 2 faecal samples should be investigated with the X-ray film method based on incubation for 2 h at 37°G. If any activity is seen the dog should be considered non-PDA. If no activity is seen the dog should be given food supplemented with 1 g crude soybean/kg body weight twice daily for a few days and a new faecal sample should be collected. If the activity remains negative the diagnosis of PDA is reliable. As the amount of crude soybean in the food increased, a dose dependent increase of faecal protease and amylase was seen as measured with the radial enzyme diffusion method (RED).     

Q fever urban cases in Romania

Q fever urban sporadic cases in Romania in the 1981-87 period are reviewed as concerns their incidence, seasonality and epidemiological data. Urban cases represented 76.8% as against 23.2% rural cases from the 134 Q fever sporadic cases detected in this period. Cases were distributed throughout all months with peaks during April (18.4% of cases) and June (19.4%). Infections were not related to contact with livestock or domestic birds or with raw milk drinking. Cases could not be identified as Q fever occupational ones. 36.7% of patients were working in nonalimentary industry and only 12.6% were involved in meat industry, veterinary or human medical practices. New studies concerning unusual sources of urban infection such as dogs, cats or urban street pigeons are emphasized.     

Nothacrobeles,n. gen., with Descriptions of Four New Species (Nematoda: Cephalobidae)

A new nematode genus, Nothacrobeles, is proposed in the subfamily Acrobelinae. Four new species are described and one new combination made. The five species exhibit a progression from short-to-long, bifurcate, elaborately fringed labial probolae, the longest probolae resembling those of species of Acrobeles.     

Meeusella and the origin of stamens

Meeusella gen. nov. is a strobilate pollen organ from the Lower Cretaceous of Transbaikalie (east of the Lake Baikal); the branched lateral branches (paracladia), if fully developed, bear a subterminal pair of stalked synangial heads. In some cases the latter are reduced to a pair of sessile heads or the paracladia are sterile. It is suggested that the synangial heads might be further reduced to a pair of bisporangiate thecae, while the paracladium apex between them might form a prominent connective of a typical stamen. ▭ Androecium, androclade, angiosperms, proangiesperms, stamen, evolutionary morphology.     

Comparative Ultrastructure and the Evolution of Nemertines

Nemertines are traditionally viewed as acoelomates with bloodvascular systems and a specialized cavity housing an eversibleproboscis, or, as coelomates with modified coelomic cavitiesforming the rhynchocoel, lateral vessels and gonadal sacs. Comparativeultrastructural data such as cell polarity, the occurrence ofpodocytes and mesodermal cells with rudimentary cilia for proboscis,rhynchocoel, lateral and dorsal vessels, and gonadal liningsare consistent with their interpretation as modified coelomiccavities as found, analogously, in the higher leeches. Theseand additional data regarding musculature, connective tissue,glia-like cells and gametes for 13 species affirm that nemertinesare intermediate between full-blown coelomate and acoelomategrades of organization. A comparison of ultrastructural details,however, indicates that their acoelomate attributes evolvedsecondarily from a more typical coelomate condition.