Genetic control over the duration of G1 phase

or fi y G₁ , .     

Transposase and cointegrase: specialized transposition proteins of the bacterial insertion sequence IS21 and related elements

The bacterial insertion sequence IS21 shares with many insertion sequences a two-step, reactive junction transposition pathway, for which a model is presented in this review: a reactive junction with abutted inverted repeats is first formed and subsequently integrated into the target DNA. The reactive junction occurs in IS21-IS21 tandems and IS21 minicircles. In addition, IS21 shows a unique specialization of transposition functions. By alternative translation initiation, the transposase gene codes for two products: the transposase, capable of promoting both steps of the reactive junction pathway, and the cointegrase, which only promotes the integration of reactive junctions but with higher efficiency. This review also includes a survey of the IS21 family and speculates on the possibility that other members present a similar transpositional specialization.     

Alterations in the levels of cAMP and cGMP after decentralization of the rat superior cervical ganglion

Summary After cutting the preganglionic nerve trunk of the rat's superior cervical ganglion, the levels of cAMP and cGMP were measured in a postoperative period of between 3 and 21 days. After 3 days, cAMP and cGMP showed a decrease by 48 and 33% respectively, followed by a partial recovery after 7 to 21 days.This work was supported by the Deutsche Forschungsgemeinschaft (SFB 70).     

Fetal hypophysis as the main source of serum TSH in fetal rat

Decapitation performed at days 17-18 leads to a drastic drop (82%) in blood TSH of 19 and 21-day-old rat fetuses below the mother's level. 125I-TSH injected at 21 days into the mother's bloodstream is not found in fetal blood. The fetal hypophysis is the main source of fetal plasmatic TSH.     

Effects of DL-propranolol on the thermoregulatory responses of rats at different ambient temperatures

Summary Direct administration of propranolol (100–400 g) into the lateral cerebral ventricle of rats produced a dose-dependent hypothermia at ambient temperatures (T_a) of 8 and 22°C. The hypothermia was due to decreased metabolism and cutaneous vasodilation. The hypothermia induced by propranolol was antagonized by pretreatment with isoproterenol (50 g).This work was supported by the grants from the National Science Council (Republic of China) and the Pjing-Ling Neurological Foundation (Veterans General Hospital). The authors are grateful to Mr C.C. Wei for generous support.     

Effect of abrupt withdrawal of chronically administered β-blocking drugs on cardiac sensitivity in the rat

Summary Increased tachycardia to isoprenaline was observed in pithed rats 2 days after withdrawal of propanolol but not after withdrawal of atenolol (a cardioselective drug) or LL 21-945 (a long acting beta-blocking drug).Acknowledgments. We are grateful to Sandoz Ltd for a gift of LL 21-943 and to I.C.I. for gifts of propranolol and atenolol.     

Fetal hypophysis as the main source of serum TSH in fetal rat

Summary Decapitation performed at days 17–18 leads to a drastic drop (82%) in blood TSH of 19 and 21-day-old rat fetuses below the mother's level.¹²⁵I-TSH injected at 21 days into the mother's bloodstream is not found in fetal blood. The fetal hypophysis is the main source of fetal plasmatic TSH.     

Na, K ATPase activity during early postnatal development of the rat submandibular gland

The activity of the ouabain-sensitive Na, K ATPase was measured in membrane fractions of the submandibular gland of 1-, 7-, 14- and 21-day-old rats. This activity increased with age and reached adult levels by 21 days.     

Na,K ATPase activity during early postnatal development of the rat submandibular gland

Summary The activity of the ouabain-sensitive Na, K ATPase was measured in membrane fractions of the submandibular gland of 1-, 7-, 14- and 21-day-old rats. This activity increased with age and reached adult levels by 21 days.     

Overexpression of copper-zinc superoxide dismutase in trisomy 21

Down's syndrome (DS), the most frequent of congenital birth defects, results from the trisomy of chromosome 21 in all cells of affected patients. This disease is characterized by developmental anomalies, mental retardation and features of rapid aging, particularly in the brain, where the occurrence of Alzheimer's disease is observed in trisomy 21 patients over the age of 35. Copper-zinc superoxide dismutase (CuZnSOD) is one of the proteins encoded by chromosome 21 (21q22.1). As a consequence of gene dosage excess, CuZnSOD activity is increased by 50% in all DS tissues. This work reports the SOD activity of a population of DS patients with complete trisomy 21, partial trisomy 21, translocations and mosaicism, in order to confirm the gene dosage effect of SOD on the clinical features of DS, and to help to establish which is the critical region of chromosome 21 in DS. CuZnSOD was measured in red blood cells using the Minami and Yoshikawa method. In the population with complete trisomy 21, SOD activity was increased by 42%; in the population with partial trisomy 21, translocations and mosaicism, SOD activity was normal. In the population diagnosed as DS, but not karyotyped, SOD activity was increased by 28%. No differences between sexes or among ages were found. We conclude that the 21q22.1 segment is not the critical region responsible for DS, as we have found normal SOD activity in patients with the clinical features of DS.     

Recent advances in the genetics of schizophrenia

The genetic etiology of schizophrenia, a common and debilitating psychiatric disorder, is supported by a wealth of data. Review of the current findings suggests that considerable progress has been made in recent years, with a number of chromosomal regions consistently implicated by linkage analysis. Three groups have shown linkage to 1q21-22 using similar models, with HLOD scores of 6.5, 3.2, and 2.4. Other replicated loci include 13q32 that has been implicated by two independent groups with significant HLOD scores (4.42) or NPL values (4.18), and 5p14.1-13.1, 5q21-33, 8p21-22, and 10p11-15, each of which have been reported as suggestive by at least three separate groups. Different studies have also replicated evidence for a modest number of candidate genes that were not ascertained through linkage. Of these, the greatest support exists for the DRD3 (3q13.3), HTR2A (13q14.2), and CHRNA7 (15q13-q14) genes. The refinement of phenotypes, the use of endophenotypes, reduction of heterogeneity, and extensive genetic mapping have all contributed to this progress. The rapid expansion of information from the human genome project will likely further accelerate this progress and assist in the discovery of susceptibility genes for schizophrenia. A greater understanding of disease mechanisms and the application of pharmacogenetics should also lead to improvements in therapeutic interventions. Received 11 May 2001; received after revision: 20 July 2001; accepted 18 September 2001     

Retroaldol transformations in the westphalen diol series

Zusammenfassung Durch Behandlung mit Kalilauge erleidet 5-methyl-19-norcholestan-9, 10-diol-3, 6-dione eine Retroaldolisomerisierung unter Bildung des 10-Hydroxy-Isomers. Letzteres wurde als Hemiketalderivat isoliert. Bei drastischer Behandlung mit Alkali gehen beide Isomere in ein Anthrasteroid über.     

Influence of N-methylformamide on the development, the NAD synthesis, and the activity of the ADPR transferase of rat embryos

When N-methylformamide is administered to rats on the 11th day of pregnancy approximately 50% of the fetuses are resorbed and a reduced weight of the developed animals is found in comparison to the controls on the 21th day (delivery by Caesarian section). The toxic effect is increased by using nicotinamide and methionine. If a combination of these substances is employed practically all fetuses are resorbed. Tryptophan, however, has a considerably protective influence. N-Methylformamide has no influence on the NAD-synthesis induced by nicotinamide or tryptophan. It does, however, inhibits the activity of the ADPR transferase.     

Synthesis of sulfated glycosaminoglycans by the three cell types of the rabbit cornea in culture.

Rabbit corneal cells were cultivated for 21 days and then exposed to Na235SO4, a precursor of sulfated glycosaminoglycans (GAG). All 3 cell types of the cornea, the fibroblasts, the epithelial as well as the endothelial cells, synthesize GAG. The fractionation-patterns of the epithelial and endotherlial GAG are almost identical and differ clearly from the one of fibroblastic GAG.     

Fibroblast growth factor 21: an overview from a clinical perspective

Fibroblast growth factor 21 (FGF21) has been proposed as a novel putative therapeutic agent in type 2 diabetes. A large amount of data, predominantly obtained from murine models but also from non-human primates, suggest that FGF21 ameliorates obesity-associated hyperglycemia and hyperlipidemia primarily via effects on adipose tissue and the pancreas. In addition, FGF21 has been reported to play a pivotal regulatory role in starvation and ketosis. However, while it is clear that FGF21 has potent effects in vivo in several animal models, the exact mechanisms remain elusive. Moreover, very recent results from different human cohort studies have shown a paradoxical regulation of plasma FGF21 in obesity and type 2 diabetes as well as other important qualitative differences in the effects and regulation of FGF21 between rodents and humans. This review focuses on the most recently published data on FGF21 with emphasis on results obtained in humans.     

Adenyl cyclase activity of the cell membrane throughout the cell cycle: ultrastructural study of the cell line BHK 21/C 13]

Adenylate cyclase activity in the surface membrane of baby Hamster kidney (BHK 21/C13) cells is ultrastructurally studied as a function of the cell cycle. Cells are synchronized by a physical method suited to structural and functional investigations. The activity is highest through G1, decreases in S, markedly drops as cells traverse G2 and is very low or often seems not present at all in M.     

On the distribution of plasma L-asparaginase

The guinea-pig, Cavia porcellus, is unusual in possessing plasma L-asparaginase, an enzyme with anti-tumor activity, 21 additional species have been examined as to the presence of this enzyme: the results confirm and extend its remarkably limited species distribution.     

Pathological changes in the liver of mice given 2,3,7,8-tetrachlorodibenzo-p-dioxin.

In C57BL/6 mice a single oral dose of 2,3,7,8-tetrachlorodibenzodioxin (LD50 126 mug/kg) results in loss of body weight and death with an enlarged fatty liver after ca. 21 days. A progressive necrotic centrilobular liver lesion is also seen.     

Rate of tryptophan hydroxylation in vivo in brain nuclei of genetically hypertensive rats of the Lyon strain

The rate of tryptophan hydroxylation in vivo is unaltered in brain areas of 5, 9 and 21 week-old Lyon genetically Hypertensive (LH) rats as compared to both Lyon Normotensive (LN) and Low Blood Pressure (LL) rats, except for a decrease in the C1 area of the medulla oblongata in 9 week-old animals.     

Synthesis of sulfated glycosaminoglycans by the three cell types of the rabbit cornea in culture

Summary Rabbit corneal cells were cultivated for 21 days and then exposed to Na₂ ³⁵SO₄, a precursor of sulfated glycosaminoglycans (GAG). All 3 cell types of the cornea, the fibroblasts, the epithelial as well as the endothelial cells, synthesize GAG. The fractionation-patterns of the epithelial and endothelial GAG are almost identical and differ clearly from the one of fibrolastic GAG.Supported by SNSF, grant No. 3.534.71.