Elevation of plasma tyrosine after a single oral dose of L-tyrosine.

Plasma tyrosine concentrations in twelve normal, fasting human subjects were significantly elevated 2–8 hours after they ingested 100 mg/kg or 150 mg/kg tyrosine. Mean plasma tyrosine levels were maximal after 2 hours, rising from $\text{69 ± 3.9}\text{to}\text{154 ± 9.5}\text{nmols/ml}\text{(}\text{X}\text{±}\text{SEM}\text{)}$ after the 100 mg/kg dose and to 203 ± 31.5 nmols/ml after the 150 mg/kg dose (p ≤ 0.001 for both doses). The mean tyrosine ratio (defined as the ratio of plasma tyrosine concentration to the sum of the concentrations of six other neutral amino acids that compete for the same blood-brain barrier uptake system) increased from $\text{0.10 ± 0.02}\text{to}\text{0.28 ± 0.04 (}\text{X}\text{±}\text{SEM}\text{)}$ 2 hours after the 100 mg/kg dose (p ≤ 0.001) and to 0.35 ± 0.05 2 hours after the 150 mg/kg dose (p ≤ 0.005). No side effects of orally-administered L-tyrosine were noted.     

Early alterations in rat liver chromatin structure after a single dose of diethylnitrosamine

In the chromatin of 24-h regenerating rat livers, derivative melting profiles are characterized by a high proportion of transitions above 90°C. After the injection of diethylnitrosamine there is a rapid shift to lower melting temperatures. This is due to a rearrangement of the chromatin to higher amounts of nucleosomal components but possibly also a consequence of chemical modifications and conformational alterations of the DNA. In the nonregenerating liver essentially the same observations can be made, although reactions proceed significantly slower. These results are in good agreement with the observation that carcinogens are more active in tissues stimulated to rapid proliferation as compared to resting tissues.     

Rapid return of cyclo-oxygenase active platelets in dogs after a single oral dose of aspirin

A single dose of oral aspirin in human subjects inhibits the aggregation response of platelets to arachidonate and other agents for approximately one week after ingestion. In the present study we have evaluated the rate at which cyclo-oxygenase active platelets return to the circulation in humans and dogs and compared the response curves obtained to improvements in cyclo-oxygenase activity produced by the aspirin platelets. After a single dose of aspirin, dog platelet function was compromised for several days. Normal responses to arachidonate and other aggregating agents were restored six days after aspirin, and the pattern of recovery was the same for dogs and human subjects. However, cyclo-oxygenase active platelets returned to the circulation in dogs more rapidly than in humans and chemical competence was restored in both species well before correction of the defective response to aggregating agents. The delay of 1-3 days before return of significant numbers of cyclo-oxygenase active platelets most likely reflects acetylation of bone marrow megakaryocytes by the drug. More rapid return of chemically competent cells in dogs than humans probably relates to the more rapid turnover and shorter life span of canine platelets. The basis for the discrepancy in return of chemical integrity compared to functional activity after aspirin in vivo compared to simultaneous correction of chemistry and function when 10% normal platelets are added to aspirin platelets in vitro remains unresolved.     

Retention of cadmium in organs of the rat after a single dose of labeled cadmium-3-phytate

Because of the low safety factor estimated for the normal content of Cd in human foods, it is important to establish the influence of food constituents such as phytate on the bioavailability of this toxic metal. We studied the retention of radioactive¹⁰⁹Cd administered to rats as a chloride or a phytate in a single dose by stomach tube. The animals were fed either a normal rat chow containing 0.29% of phytate or a low phytate diet containing less than 0.1% phytate. Highly elevated levels of¹⁰⁹Cd were found only in the animals that were supplied with¹⁰⁹Cd as a chloride and had been fed the low phytate diet. In the animals supplied with¹⁰⁹Cd as a phytate, which had also received the low phytate diet, the levels of¹⁰⁹Cd in the intestine were as high as those in the group mentioned before, but the retentions in all other tissues resembled those of the respective groups fed the normal chow. The findings indicate that phytate is responsible for a considerable decrease in the intestinal absorption of Cd. Furthermore, it appears to exert an influence on the kinetics of Cd retention in the intestine.     

Dynamics of structural changes in rat liver after single dose of gamma-irradiation

Histological changes and alterations in biophysical and biochemical parameters in liver of gamma-irradiate rats have been investigated. The gamma-irradiation of the whole body of rats with a single dose of 1 Gy did not cause any impairments of beam structure of rat liver, but resulted in the lymphocytic infiltrations of portal tracts which were not accompanied by formation of spotty areas of necrosis in adjacent areas of lever parenchyma. gamma-Irradiation stimulated proliferation of the hepatocytes and induced time-dependent mitochondrial structure lesions. Post-irradiation changes in cell cytoplasm appeared as disordering in reticulum-endothelial system, among them enlarging and fragmentation of its cisterns, cytoplasmic vacuolization, enhancement of the number of lysosomes and of the lipid inclusion contents. These facts revealed the mobilization of the additional energy resources for recovery of metabolic processes in rat liver. Post-irradiation increase of the level of the hepatocyte membrane lipid peroxidation products preceded liver morphological alterations. The membrane lipid microviscosity decreased in 1 and 3 days after irradiation. As a result of damages of hepatocyte membrane, the activity of the alanin- and asparagin-aminotransferases in blood serum increased 6 hours after. We can conclude that the whole body single gamma-irradiation with a dose of 1 Gy leads to the reversible but significant damages to the rat liver cell membrane structures. These damages might be the reason of radiation-induced liver morphological alterations.     

Blood plasma levels of deoxynivalenol and its de-epoxy metabolite in broilers after a single oral dose of the toxin

To evaluate the transfer of deoxynivalenol (DON) and its de-epoxy metabolite (de-epoxy-DON) in the plasma of chicken, mashed oats naturally contaminated with 9.5 mg DON/kg were fed to four broilers (35 days age) at a dose of 20 g/bird. Blood samples were then collected from two birds at 1 h, 3 h, and 5 h post-feeding, while from the other two birds at 2 h, 4 h, and 6 h post-feeding. Analysis of DON and de-epoxy-DON was carried out by using liquid chromatography-tandem mass spectrometry after clean-up with immunoaffinity columns. At 1 h, 3 h, and 5 h post-feeding, the average values of plasma DON were 0.35 ng/ml, 0.20 ng/ml, and 0.15 ng/ml, respectively. The corresponding average values of de-epoxy-DON at these time points were 0.70 ng/ml, 0.80 ng/ml, and 0.25 ng/ml, respectively. The sum of DON and de-epoxy-DON appearing in the plasma at 1 h post-feeding in these birds was estimated to be 0.044% of the total DON fed. At 2 h, 4 h, and 6 h post-feeding, the average values of plasma DON were 0.85 ng/ml, 0.45 ng/ml, and 0.30 ng/ml. De-epoxy-DON could not be detected in the birds sampled at 2 h, 4 h, and 6 h post-feeding. The total amount of DON appearing in the plasma at 2 h post-feeding in these birds was estimated to be 0.036% of the DON fed. These data show that the absorption rate of DON is very low in broilers and that there is also a rapid transformation, and clearance from plasma. Furthermore, there appeared to be individual variability in the capacity of birds to de-epoxidise DON.     

Apocynaceae V: Seasonal variation in chromosome association and male sterility in a single floweringTabernaemontana divaricata

A single-flowering, male sterile variety ofTabernaemontana divaricata (2n=22) had a high frequency of univalents. Observations on material fixed at nine periods during the year showed univalent frequency to be negatively correlated with temperature. Chromosome association was normal only at temperatures around 40°C. As pollen sterility did not vary with temperature, it was concluded that it had developmental-genetic rather than meiotic causes.     

Distribution and peroxidative oxidation of 2-t-butyl-4-methoxyphenol in rat tissues after a single intraperitoneal dose

The distribution of 2-t-butyl-4-methoxyphenol (BHA) and its conversion to 2,2'-dihydroxy-3,3'-di-t-butyl-5,5'-dimethoxydiphenyl (di-BHA) in rat tissues at different times (1-96 hr) following the intraperitoneal administration of a single dose of BHA (32 mg kg-1 body weight) were monitored by gas chromatography-mass spectrometry (GC/MS) analysis of both compounds. High BHA levels were found in the intestine and liver persisting up to 24 hours (5.5-20.7 and 1.8-3.3 micrograms g-1 wet weight, respectively). In these tissues, values of the area under the experimental concentration curve (AUC0-24) were 285 and 49 times higher, respectively, than those observed in plasma (945 ng mL-1 hr), AUC0-24 values in kidney, spleen, erythrocytes, and brain were 2-7 times higher, whereas values below those found in plasma were observed in lung and muscle. The metabolite di-BHA could be detected in the intestine, kidney, and spleen, amounting to 5-8% of BHA. These findings indicate that rat intestine is capable of transforming in vivo BHA into di-BHA even when the former compound is administered intraperitoneally and that this capacity is shared by the kidney and spleen.     

Cytoplasmic male sterility in barley

The maternal male sterile barley msm1 with or without a dominant gene, Rfmla, which restores male fertility, was studied. Determined with SDS-PAGE, the polypeptide pattern in the anthers of unrestored msm1 plants remains juvenile in the middle of anther development, two major zones being absent or weak. At the stage when anther development stops in msm1 plants, the anther proteins appear to be hydrolyzed to short-chain peptides. Restored plants, heterozygous for the restorer gene, Rfmla, behaved like the near-isogenic normal barley, cv. Adorra. The total leaf protein pattern of young leaf tissue and the chloroplastidic membrane protein pattern are normal in msm1 cytoplasm when studied with this technique. Chlorophyll b is unnecessary for restoration by Rfmla, though the restored plants have a lower chlorophyll a/b ratio than an unrestored plant in the mature stem leaf. Mature stem leaf pieces of unrestored msm1 plants were induced to senesce with 20 mM NaCl solution. This senescence was inhibited by exogenous kinetin. Leaf pieces of restored msm1 plants or those of near-isogenic normal barley behaved in the same way in the NaCl solution as in distilled water. Many features of the physiology of restored plants can be explained as the functions of cytokinins. Kernels of male sterile plants have a more rapid root elongation at germination than near-isogenic normal barley.     

Cytoplasmic male sterility in barley

Summary Restoration in the msm1 cytoplasm of barley (Hordeum vulgare L. s.l.) was studied from the standpoint of population biology and physiological effects on kernel protein. Restorer genes of 82 accessions of wild barley (ssp. spontaneum) from Israel were determined. 38% of the accessions were maintainers of sterility, 48% were partial restorers, and 14% were restorers. Fourteen dominant restorer genes are described, and evidence for three cases of allelism to Rfm1a is presented. The restorer accessions and their designated gene symbols are: PI 282636 (Rfm,,e), PI 282637 (Rfm,f), PI 282646 (Rfm,,g), PI 284742 (Rfm,h), PI 284743 (Rfm,,i), PI 284753 (Rfm,,j), PI 284755 (Rfm1d), PI 296838 (Rfm,,k), PI 296850 isolate 16/7 (Rfm,,l), PI 296853 (Rfm,,m), PI 296856 (Rfm1b), PI 296899 (Rfm,,n), PI 296919 (Rfm1c), PI 296944 (Rfm,,o). PI 296850 was found to contain both a restorer and a non-restorer genotype. None of the PI accessions with a restorer gene is a carrier of an msm1-type male sterilizing cytoplasm. In the present sample, plants with restoration ability occurred with a higher frequency in the material from the Judean Foothills than that from the other regions of Israel. The greater adaptive value of plants with restoration ability on certain soil associations in semiarid and subhumic climate is suggested. The considerable frequency of restorers and partial restorers in male fertile cytoplasm suggests that the restoration system evolved before the msm1-type cytoplasm. In the nuclear genotype near-isogenic with either Adorra or Risø 1508, msm1 plants heterozygous for Rfm1a produced 98.6 or 98.5% of the protein content in the respective recurrent pollen parent varieties. The amino acid compositions of the derivatives differed little from those of the varieties. In the derivatives, a consistent decrease was found in tryptophan, and consistent increases in isoleucine, phenyalanine, lysine, histidine, and arginine. In relation to glucose consumption, the bioenergetic cost calculated for the amino acid patterns found in the restored msm1 derivatives was slightly higher than that for the near-isogenic pollen parent varieties. The results suggest that the restorer gene in the heterozygous state normalizes the physiology of msm1 cytoplasm to a great extent.     

Cytoplasmic male sterility in barley

Summary The associations between seedling reactions to three fungal pathogens (Puccinia hordei, Pyrenophora teres, and Rhynchosporium secalis) or between adult plant reaction to Rh. secalis and the male fertility restoration ability of msml cytoplasm were studied in about 100 accessions of Hordeum spontaneum. Significant differences in the severity of infection between classes of restoration ability were observed with two cultures of P. hordei (751 and 7,649) and with Rh. secalis on adult plants in the field. The cultures 7,432, 751 and 7,649 of P. hordei showed significant positive correlations between infection severity and restoration percentage. The culture 7,620 of P. hordei displayed a significant negative correlation. Rh. secalis (cultures 492A and 531 combined) on seedlings and the natural field infection in the 1978 season showed significant positive correlations. The accession class with the partial restoration ability of 0.1 to 5.0% of the four arbitrary classes (0.0, 0.1–5.0, 5.1–55.0, and 90.1–100%), displayed the lowest mean severity of infection in six of the eleven tests. Some frequently appearing races of these pathogens may operate as selective agents in the maintenance of restoration ability in the original spontaneum populations.     

Cytoplasmic male sterility in barley

Summary The effect of the msm1 cytoplasm of barley (Hordeum vulgare L.) on kernel protein and lysine was studied using the near-isogenic, unrestored derivatives of seven barley varieties. With normal lysine varieties, Adorra, Bomi, CI 4362, and Hankkija's Eero, the msm1 cytoplasm produced an average of one percentage point more protein than did the normal cytoplasm of the same varieties. There was no difference between the two cytoplasms with respect to their effect on the lysine content. With high lysine varieties, Bomi Risø mutant 13, Bomi Risø mutant 1508, and CI 3947, msm1 produced almost one percentage point more protein but protein with a somewhat decreased lysine content.Induced partial spike fertility in normal Adorra was found to be associated with lysine in meal (r=–0.999), with protein in meal (r=–0.984), and with lysine in protein (r=0.941). Removal of the spikes on the secondary tillers affected both the protein and its lysine content. It is suggested that good spike fertility is an important pre-requisite when selecting high lysine and/or high protein segregants or mutants.     

Mechanism of male sterility in Petunia

Summary The free amino acid contents in the anthers of male fertile, cytoplasmic male sterile (cms) and genic male sterile (gms) petunia lines were compared at different developmental stages of the male gametophyte. Quantitative differences in the amounts of free amino acids were found between the fertile and male sterile lines and between the cms and gms lines. The differences between the sterile lines were correlated with the different developmental stages at which the breakdown in microsporogenesis occurred. In the Rosy Morn (RM) cms line, where breakdown of microsporogenesis occurred at the end of prophase 1, there was an associated increase in asparagine and decrease in the other amino acids. In the RM gms line, in which breakdown occurred at the tetrad stage, an accumulation of asparagine in the anthers corresponded with an accumulation of glutamine beginning at prophase 1. Compared with fertile anthers, the sterile anthers accumulated much proline at the early meiotic stages, but no -aminobutyric acid. Comparison of the free amino acids of the fertile and the male sterile lines indicates that certain biochemical events leading to breakdown of microsporogenesis precede the observed cytological breakdown. The results from adding asparagine and glutamine to extracts of anthers at different developmental stages suggest that the amino acid balance may contribute to the changes in pH in the fertile and male sterile anthers which we observed previously.Contribution from the Volcani Center, Agricultural Research Organization Bet Dagan, Israel. 1972 Series, No. 2083 E.     

Morphofunctional state of the rat male reproductive system after chronic low intensity irradiation at a dose of 1.0 Gy

It was studied the morphofunctional state of rat male reproductive system after chronically exposure to low intensive gamma-irradiation in early ontogenesis. After radiation with a total dose of 1.0 Gy it was revealed the decrease of the testes and epididymis weight, dysbalance in the ratio of different spermatogenic cells, changes in nucleic acid content and discoordination of bioenergetic metabolism in testes. Disturbance in rat male reproductive system retained in remote period (180 days after irradiation).     

A novel potent indazole carboxylic acid derivative blocks spermatogenesis and is contraceptive in rats after a single oral dose

Women have historically been the focus for development of new contraceptive methods. The National Institutes of Health, World Health Organization, and Institute of Medicine have stressed the need to develop nonhormonal, nonsteroidal male contraceptive agents. We report results from initial dose-ranging studies of a new indazole carboxylic acid analogue, gamendazole. An infertility rate of 100% was achieved in seven out of seven proven-fertile male rats 3 wk after a single oral dose of 6 mg/kg of gamendazole. Fertility returned by 9 wk in four of seven animals, with typical numbers of normal-appearing conceptuses. A fertility rate of 100% returned in four of six animals that became infertile at a single oral dose of 3 mg/kg of gamendazole. No differences in mating behavior were observed in either of the gamendazole-treated groups versus the control (vehicle-only) group. In the animals that showed reversible infertility, a transient increase in circulating FSH levels coincided with an initial decline in inhibin B levels after administration of gamendazole, but no other significant changes in circulating reproductive hormones were observed. Gamendazole inhibited production of inhibin B by primary Sertoli cells in vitro with a median inhibitory concentration of 6.8 thorn+/- 3.0 (SEM) (3/4)x 10(-10) M, suggesting that Sertoli cells are a primary target. A biotinylated gamendazole analogue revealed cytoplasmic and perinuclear binding of gamendazole in primary Sertoli cells. Gamendazole represents the most potent new oral antispermatogenic indazole carboxylic acid to date. Our results, however, demonstrate that additional dose-finding studies are required to improve reversibility and widen the therapeutic window before more detailed drug development of this potential nonhormonal male contraceptive agent can occur.     

Calcium absorption in corticoid treated subjects effects of a single oral dose of calcitriol

We compared the fractional absorption of calcium (FACa, 6 h, % TD) and the radiocalcium transit (% TD per min) in seven glucocorticoid-treated patients (10-25 mg prednisolone per day) and in seven normal subjects, in the basal state and 12 h after an oral dose of synthetic 1,25-(OH)2D (3 micrograms). In the basal state, the radiocalcium transit was significantly decreased (P less than 0.02) at 15 min in patients treated with prednisolone, but FACa at 6 h was not significantly decreased (51 +/- 5 vs. 60 +/- 5% TD). 12 h after an oral dose of 1,25-(OH)2D which resulted in supraphysiologic plasma levels, FACa increased significantly (P less than 0.02) in both groups but the peak absorption rate of Ca remained lower in the corticoid-treated patients than in controls (P less than 0.02). The results suggest that glucocorticoids decrease the 1,25-(OH)2D-dependent transport of calcium across the proximal small intestine.