Rapid and simultaneous determination of monoamine oxidase A and monoamine oxidase B activities in mouse brain homogenates by liquid chromatography with electrochemical detection

Sensitive and rapid enzymatic assays have been developed and optimized to measure the separate and combined activities of monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B) in mouse brain tissue homogenates using liquid chromatography with electrochemical detection (LCEC). The selectivity for the two isozymes is primarily afforded by use of selective substrates, 5-hydroxytryptamine (5-HT) for MAO-A and 3-methoxy-4-hydroxybenzylamine (MHBA) for MAO-B. The selectivity of the separate assays is further enhanced by the use of inhibitors, deprenyl to block MAO-B and clorgyline to block MAO-A. The dual assay procedure, which employs no inhibitors, shows remarkably enhanced selectivity for each of the isozymes through the use of the two substrates; the preferred substrate for one isozyme acts as an effective competitive inhibitor of the nontargeted substrate for that isozyme, leading to substantially decreased activity for the latter substrate. Using the dual assay, kinetic constants determined for MAO-A (mean +/- SD) were: Km,5-HT = 39 +/- 7 microM, Vmax,5-HT = 37.6 +/- 2.1 pmol/mg wet tissue/min, Km,MHBA = 341 +/- 75 microM, and Vmax,MHBA = 27.7 +/- 2.3 pmol/mg wet tissue/min; those for MAO-B were: Km,MHBA = 108 +/- 11 microM, Vmax,MHBA = 44.3 +/- 1.2 pmol/mg wet tissue/min, Km,5-HT = 1704 +/- 122 microM, and Vmax,5-HT = 12.0 +/- 0.3 pmol/mg wet tissue/min. The separate isozyme procedures, when used without selective inhibitors, reflect only 88.3% of the MAO-A activity using the 5-HT velocity and only 66.0% of the MAO-B activity using the MHBA velocity. On the other hand, when the dual assay is employed, 98% of the observed 5-HT velocity can be directly attributed to MAO-A, and 94% of the observed MHBA velocity can be directly attributed to MAO-B. The dual assay was employed to demonstrate the relative change in the activity of these two enzymes in whole mouse brain between 27 and 74 days of age. During this time, the MAO-B activity increased from approximately 40 to approximately 60% of the total MAO activity. Under typical conditions, results can be easily obtained from any of the three procedures outlined for 100 samples in less than 2 working days, including only 3.5 h for the LCEC portion.

[Effects of Panax notoginseng saponins on monophasic action potentials of heart and automaticity and contractility of isolated atria]

The effects of Panax notoginseng saponins (PNS) on monophasic action potentials (MAP) recorded from the myocardial surface by means of contact electrode were studied in 30 open-chest rabbits. The MAPA was increased and MAPD50, MAPD90 were prolonged with PNS (100, 200 mg.kg-1, iv), while the Vmax remained unchanged. PNS (300-1200 micrograms.ml-1) inhibited the automaticity of isolated guinea pig right atria and the contractility of the left atria. The positive inotropic action of ouabain (0.2 mumol.L-1) on isolated guinea pig left atria was decreased in the presence of PNS 300 micrograms.ml-1.

[Volatile oil in Ephedra sinica Stapf. and its processed products by GC-MS]

This paper deals with the changes in contents and chemical composition in the volatile oil of Ephedra sinica before and after processing. The results indicate that after processing, the more the substances of low boiling point, the higher their contents and vice versa. The changes are particularly obvious in yellow-fried Ephedra sinica.

Neuropeptide gene expression in transgenic animals

Transgenic animal techniques offer today's neuroscientist the ability to experimentally manipulate neurosecretory systems with a precision undreamt of by our predecessors. The range of techniques now available, building as it does on our growing knowledge of physiological systems at the inter- and intercellular level, allows us to critically define molecular lesions and ask about their consequences to the whole organism. Neuroscientist should grasp the opportunities afforded by these recent developments.

[Clinical observation of macular disease in patients with diabetic retinopathy]

The population was 65 cases (122 eyes) of diabetic macular disease. Background diabetic retinopathy was observed in 40 eyes, i.e., 32.80%. For the 82 eyes present proliferative diabetic retinopathy, i.e., 67.20%. According to Sigelmen's classification, 17 eyes were in stage I, i.e., 13.93% of the cases; 41 eyes were in stage II, i.e., 33.60% of the cases; 40 eyes were in stage III, i.e., 32.80% of the cases; 24 eyes were in stage IV, i.e., 19.67% of the cases. There were 122 eyes in this group. The visual acuity of 66 eyes showed > or = 0.3, i.e., 54.00%, while that of 56 eyes showed 40.3 i.e. 46.00%. Nearly half patients showed low visual acuity and loss of vision. This result was responsible for the cases who were at the late stage of diabetic and with a long history of diabetic or the diabetic was poorly controlled. So the writer appeal to ophthalmologists and physicians to prescribe the effective guides to all the diabetic patients. We suggest that it is important that dynamic observation be carried out of hemorhelological manifestation and early treatment diabetic retinopathy for the clinical prevention and treatment of diabetic retinopathy.

Augmentation of rat liver regeneration by FK 506 compared with cyclosporin

The immunosuppressive drug, FK 506, increased the regeneration response that follows 40% and 70% hepatectomy in rats. The effect was similar to that obtained with cyclosporin.

The effect of different types of hepatic injury on the estrogen and androgen receptor activity of liver

Mammalian liver contains receptors for both estrogens and androgens. Hepatic regeneration after partial hepatectomy in male rats is associated with a loss of certain male-specific hepatic characteristics. In this study we investigated the effects of lesser forms of hepatic injury on the levels of estrogen and androgen receptor activity in the liver. Adult male rats were subjected to portacaval shunt, partial portal vein ligation, hepatic artery ligation, or two-thirds partial hepatectomy. Another group of animals was treated with cyclosporine. At the time of sacrifice the livers were removed and used to determine the estrogen and androgen receptor activity in the hepatic cytosol. A significant reduction (p less than 0.05) in the hepatic cytosolic androgen receptor activity and a slight increase in the estrogen receptor activity occurred following total portosystemic shunting. Partial ligation of the portal vein, which produces a lesser degree of portosystemic shunting, had no effect on the levels of the estrogen and androgen receptor activity present within hepatic cytosol. Cyclosporine-treated animals had significantly greater (p less than 0.01) levels of estrogen receptor activity in the hepatic cytosol compared to vehicle-treated control animals. Levels of estrogen and androgen receptor activity within the hepatic cytosol remained unchanged after ligation of the hepatic artery. The reduction in the cytosolic estrogen and androgen receptor activity in the liver after partial hepatectomy was confirmed. In summary, certain types of hepatic injury are associated with profound changes in the estrogen and androgen receptor content within the liver.

Studies on the regulation of renin genes using transgenic mice

Transgenic mice are being used as an assay to identify the DNA sequences that direct the tissue specificity and physiological regulation of murine renin gene expression. In initial studies, a DNA segment encoding the duplicated renin gene, Ren-2, has been injected into the pronuclei of fertilized eggs homozygous for the Ren-1c allele. The 24 kb XhoI fragment utilized consists of 5.3 kb of upstream flanking sequences and 9.5 kb of 3' flanking sequence in addition to the 10 kb segment encoding the 9 exons of the natural gene. Seventeen transgenic founder mice were identified of which at least 7 exhibited evidence of transgene expression. The 4 expressing lines that have been studied in detail integrated from 5 to 15 copies of the transgene but expression was not proportional to the number of copies integrated. Qualitatively, expression is detected in the correct spectrum of tissues, and submandibular gland expression of the transgene responds appropriately to known hormonal modulators. However, quantitatively, the levels of expression deviate considerably from normal.

Effect of partial portal vein ligation on hepatic regeneration

To evaluate the effect of portal hypertension and diminished portal venous blood flow to the liver on hepatic regeneration, male rats were subjected to partial portal vein ligation and subsequently to a two-thirds partial hepatectomy. The levels of ornithine decarboxylase activity at 6 h after partial hepatectomy were greater (p less than 0.001) in the rats with prior partial portal vein ligation than in those without portal hypertension. The rats with prior partial portal vein ligation also had greater (p less than 0.005) levels of thymidine kinase activity at 48 h after partial hepatectomy than did those without portal hypertension. Hepatic sex hormone receptor activity was not affected by prior partial portal vein ligation either before or after partial hepatectomy. The reductions in both estrogen and androgen receptor activity observed in the hepatic cytosol after partial hepatectomy were similar to those observed in control animals. These data indicate that animals with portal hypertension having a diminished hepatic portal blood flow have a normal capacity to regenerate hepatic mass following a hepatic resection.

Mapping of the mouse atrial natriuretic factor gene. Evidence for tight linkage to the Fv-1 locus

The importance of atrial natriuretic factor (ANF) in the regulation of salt balance and blood pressure is now widely recognized, and it would be extremely informative for both physiologists and molecular biologists to have mutants available that exhibit abnormal expression of this peptide hormone. The most direct mutation would affect the structural gene itself by altering either its coding potential or its regulation. With this aim in mind, it is of considerable interest to accurately determine the chromosomal position of the ANF gene (Anf) in the mouse. This information would permit a comparison with known mutations and provide a means of screening for mutations at this locus. Using recombinant inbred mouse strains, we undertook the mapping of the mouse Anf gene and demonstrated linkage of the gene to the Friend virus susceptibility-1 (Fv-1) locus on chromosome 4. The mapping was performed using a restriction fragment length polymorphism extant between the two parental strains. No recombination event between Anf and the Fv-1 locus was evident in any of the 34 strains tested. The assignment of Anf to this region of chromosome 4 coincides with the reported position of the cribriform degeneration mutation, which includes in its phenotype an abnormal electrolyte distribution. We have, therefore, begun studying this mutation to determine whether a defect in ANF expression is the underlying cause of the phenotype. Thus far, we have found no major DNA rearrangement close to the Anf gene.