Mapping of the spectral density function of a Cα−Hα bond vector from NMR relaxation rates of a 13C-labelled α-carbon in motilin

Summary The peptide hormone motilin was synthesised with a ¹³C-enriched -carbon in the leucine at position 10. In aqueous solution, six different relaxation rates were measured for the ¹³C–H fragment as a function of temperature and with and without the addition of 30% (v/v) of the cosolvent d ₂-1,1,1,3,3,3-hexafluoro-2-propanol (HFP). The relaxation rates were analysed employing the spectral density mapping technique introduced by Peng and Wagner [(1992) J. Magn. Reson., 98, 308–322] and using the model-free approach by Lipari and Szabo [(1982) J. Am. Chem. Soc., 104, 4546–4570]. The fit to various models of dynamics was also considered. Different procedures to evaluate the overall rotational correlation time were compared. A single exponential time correlation function was found to give a good fit to the measured spectral densities only for motilin in 30% (v/v) HFP at low temperatures, whereas at high temperatures in this solvent, and in D₂O at all temperatures, none of the considered models gave an acceptable fit. A new empirical spectral density function was tested and found to accurately fit the experimental spectral density mapping points. The application of spectral density mapping based on NMR relaxation data for specific ¹³C–¹H vector is shown to be a highly useful method to study biomolecular dynamics. Advantages are high sensitivity, high precision and uniform sampling of the spectral density function over the frequency range.Abbreviations CD circular dichroism - NOE nuclear Overhauser enhancement - NOESY two-dimensional NOE spectroscopy - INEPT insensitive nuclei enhanced by polarisation transfer - DANTE delays alternating with nutations for tailored excitation - WALTZ-16 wideband, alternating phase, low-power technique for zero residual splitting - FID Free induction decay - ppm parts per million - TSPA 3-trimethylsilyl-(3,3,2,2-d)-propionic acid - HFP d ₂-1,1,1,3,3,3-hexafluoro-2-propanol - CPMG Carr-Purcell-Meiboom-Gill - TFD time-resolved fluorescence depolarisation - CSA chemical shift anisotropy Partly presented at the symposium Dynamics and Function of Biomolecules, Szeged, Hungary, July 31–August 2, 1993.     

Effects of epidermal growth factor on deoxyribonucleic acid synthesis and stomach weight in hypophysectomized adult mice

Epidermal growth factor (EGF) or saline was administered intraperitonally to hypophysectomized adult male CD2F₁ mice or intact controls at 0700 hr. Subgroups of mice were killed at 4, 8, or 12 hr after injection. EGF was shown to stimulate [³H]TdR incorporation into DNA into several organs as previously reported. The response to EGF was found to be enhanced in both hypophysectomized and fasted mice. Differences in [³H]TdR incorporation into DNA, corneal epithelium mitotic index, RNA in pancreas and kidney of hypophysectomized and intact mice are reported. EGF was shown to result in stomach enlargement due to increased luminal contents in both hypophysectomized and intact mice.     

Reproductive performance, population dynamics and anthropometrics of the free-ranging Cayo Santiago rhesus macaques

This report summarizes demographic data collected on the Cayo Santiago colony of rhesus monkeys from 1976-1983 and compares the results with those from 1959-1964 [8,9]. For males and nonpregnant/nonlactating, pregnant, and lactating females mean (+/- 1 SD), body weights, crown-rump lengths, and ponderal indices are tabulated for each age on a large (n = 586) single sampling of this free-ranging population of macaques.     

Incidence of caries and abscesses in archeological Eskimo skeletal samples from point hope and Kodiak Island,Alaska

The incidence of caries and abscesses in 246 archeologically derived skeletal specimens from the Ipiutak and Tigara levels at Point Hope, Alaska, and 79 specimens excavated from Jones Point, Kodiak Island, Alaska were investigated. All three collections span long periods of time. Only pre-white contact specimens were used. Each specimens was sexed and aged in five year groupings, using standard techniques. Caries and abscesses were recorded by type and degree of severity and correlated with age, sex, and site of origin. All samples displayed very low caries rates and few abscesses per tooth and per individual (both observed frequencies, and frequencies corrected for postmortem loss of teeth). DMF scores were tabulated using both observed and corrected frequencies. Very heavy occlusal wear in all three samples could account for the majority of abscesses and pulp exposures, while the low caries rates are attributable to traditional diets totally devoid of refined sugars, starches, and food additives.     

Pattern of dry-matter accumulation,and nitrogen concentration and uptake as influenced by levels and methods of nitrogen application in rainfed-upland rice

Summary Dry-matter accumulation, and concentration and uptake of nitrogen increased with increasing level of nitrogen at all the stages of crop growth. The differences in nitrogen concentration due to nitrogen levels were greatest at panicle initiation stage and started becoming narrower with the advancement in crop age. Split application of nitrogen with its heavier fractions at tillering and panicle initiation stages either through soil alone or soil+foliage (1/3+1/3+1/3) resulted in higher dry-matter accumulation, and higher nitrogen concentration and uptake than other methods. The crop, on an average, removed 61 kg N/ha. Plants accumulated nearly 15% of the total absorbed nitrogen, up to tillering, 50% up to panicle initiation and 85–90% up to heading. Proportionately lesser nitrogen uptake and dry-matter accumulation at post-heading stage is an indicative of a major constraint for production efficiency of rainfed-upland rice culture.     

Immunologic unresponsiveness of mouse spleen sensitized to allogenic tumors.

CS7BL/6 mice were sensitized with an ip injection of allogeneic P-815 mastocytoma cells. Fifteen days later the spleen cells of the tumor allosensitized mice were cultured and tested for their responsiveness to mitogens and alloantigens, and for their ability to generate cytotoxic cells in vitro. The results indicate that 15 day tumor-sensitized spleen cells are hypo-responsive in mixed lymphocyte culture (MLC) with DBA/2 or AKR as stimulating spleen cells. The cells which are hypo-responsive in MLC can proliferate in response to mitogens and they also can generate cytotoxic cells in vitro. MLC reactivity recovers in about 2–3 months which is $\text{1}\text{1}\text{2}\text{–2}\text{1}\text{2}$ months after the mice have rejected their tumors. The mechanism of MLC hypo-responsiveness was investigated. The results suggest the presence of a suppressor cell which does not appear to be a macrophage or a B-cell. The suppressor cell can be separated from the cytotoxic cell and therefore appears to be a noncytotoxic T-cell.     

The restoration of the T-lymphoid system of nude mice: lower efficiency of nonlymphoid, epithelial thymus grafts.

The T-cell deficiency of nude mice is due to an abnormal differentiation of the thymus epithelium; it can be persistently corrected by grafting a neonatal thymus. However, grafted adult thymuses or epithelial thymuses are not repopulated by large numbers of host-derived lymphocytes, as is the case when a whole neonatal thymus is grafted. Furthermore, the repopulation of the spleen and lymph nodes by T cells is less pronounced than after whole neonatal thymus transplantation, and the restoration of the reactivity to T-cell mitogens is irregular. Therefore, the integrity and the age of the thymus graft are important for a good restoration of the T-lymphoid system of congenitally athymic animals.     

Analyse quantitative des remaniements intestinaux et évolution de la synthese de l'ADN

Résumé Les remainements intestinaux affectant la paroi intestinale sont quantifiés chez les larves d'un Amphibien Anoure,Alytes obstetricans, traitées par la thyroxine. La fraction correspondant à chaque zone composant la paroi est déterminée sur coupe. La répartition et la fréquence des noyaux marqués sont recherchées chez des larves ayant reçu de la thymidine tritiée.L'indice de marquage nucléaire de l'épithélium primaire tend vers zéro durant les 3 premiers jours du traitement. Ces résultats reflètent un ralentissement de la croissance du tissue, précédant sa dégénérescence et son élimination complète au 14ème jour d'immersion dans la solution hormonale.Dès de 3ème jour de traitement, un épithélium secondaire se développe à partir de cellules-souches basales. Son indice de marquqge croît, culmine au 9ème jour avec une valeur proche de 50%, puis s'abaisse. La prolifération cellulaire est plus modérée dans la zone extra-épithéliale, qui s'épaissit toutefois au cours de cette métamorphose provoquée.

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Quantitative analysis of intestinal changes and the evolution of DNA synthesis in thyroxine-treated larvae ofAlytes obstetricans. (Amphibia, Anura)

Summary Changes in the intestinal wall ofAlytes obstetricans (Amphibia, Anura) were quantified during thyroxine treatment. The relative proportion of each intestinal wall component was determined in tissue sections. Autoradiographic studies on intestine with³H-thymidine revealed the distribution and frequency of labeled nuclei.The labeling index in the primary epithelium falls to zero by 3 days. Thyroxine treatment induces a decrease in the growth rate of this tissue, just before its degeneration and complete elimination by 14 days.Three days after T₄-treatment, a secondary epithelium develops from basal stem cells. Its labeling index rises to a maximum of about 50% by 9 days, and thereafter declines. Cell proliferation is less marked in the extraepithelial zone, which nevertheless thickens during this thyroxine-induced metamorphosis.