Micropropagation ofUraria picta, a medicinal plant, through axillary bud culture and callus regeneration

Summary Micropropagation ofUraria picta, a leguminous herb, was achieved through axillary bud culture and nodal callus culture. Bud break was best when nodes were cultured on Murashige and Skoog (1962) (MS) medium supplemented with 2.6 μM α-naphthalene acetic acid and 4.4 μM N⁶-benzyladenine. Optimum shoot multiplication was observed in adenine sulphate at 2.47 μM concentration. Competent callus was initiated around the nodal ring of the explant on the basal medium supplemented with cytokinins and auxin (α-naphthalene acetic acid and N⁶-benzyladenine), which regenerated into new profusely growing shoots on transferring to 0.13 μM N⁶-benzyladenine. Shoots elongated to 5 node length with 1.11 μM N⁶-benzyladenine were rooted on half-strength MS basal medium. The rooted plants were successfully established with 80% survival. About 400 such plants were transferred to the field.     

Effect of nicotine on glycosaminoglycan metabolism in rats.

Cigarette smoking has been established as a major risk factor for atherosclerosis and also for lung cancer. Nicotine is one of the major components of cigarette smoke which is believed to be partly responsible for the deleterious effect of cigarette smoke. There was significant alteration in the concentration of glycosaminoglycans (GAG) in rats exposed to cigarette smoke. Administration of nicotine to rats has been found to decrease many of GAG fractions in the aorta, liver and heart and increase in the lungs. The increase in GAG now observed in lung tissue in rats administered nicotine and those exposed to cigarette smoke may be involved in the increased incidence of lung cancer in smokers. Increased activity of many of GAG hydrolysing enzymes indicates increased degradation of GAG. Sulphate metabolism in the liver is also significantly altered by nicotine. Thus administration of nicotine to rats caused alteration in the metabolism of GAG which are similar to those observed on exposure of rats to cigarette smoke, indicating that nicotine content of the tobacco smoke may partly be responsible for the effect on GAG observed on exposure to cigarette smoke.     

On the mechanism of a mutated and abnormally functioning gamma-aminobutyric acid (A) receptor linked to epilepsy

A recent report indicates that a lysine-to-methionine mutation (K289M) in the gamma2 subunit of a human gamma-aminobutyric acid neurotransmitter receptor, the GABA(A) receptor, is linked to generalized epilepsy with febrile seizures [Baulac et al. (2001) Nat. Genet. 28, 46-48]. This mutation caused a decreased current response to GABA [Baulac et al. (2001) Nat. Genet. 28, 46-48]. Here we determine changes that occur in the mechanism of opening and closing of transmembrane channels formed by the GABA(A) receptor as a result of this mutation. The K289M mutation was introduced into the gamma2L subunit of the rat GABA(A) receptor, and the mutated subunit was coexpressed with the alpha1 and beta2 subunits in HEK293 cells. Transient kinetic techniques suitable for investigating reactions on cell surfaces with a microsecond-to-millisecond time resolution [Hess, G. P., and Grewer, C. (1998) Methods Enzymol. 291, 443-473] were used. They allow one to determine not only the channel-opening probability and rates of receptor desensitization but also the opening and closing rates of the mutated GABA(A) receptor channel. The channel-opening equilibrium constant of the mutated receptor was found to be 5-fold lower than that of the wild type. We calculated that this decrease in the channel-opening equilibrium accounts for the dysfunction of the mutated receptor. We discuss how a knowledge of the mechanism of the mutated receptor indicates an approach for alleviating this dysfunction.     

Insulin-secretagogue activity and cytoprotective role of the traditional antidiabetic plant Scoparia dulcis (Sweet Broomweed)

Scoparia dulcis (Sweet Broomweed) has been documented as a traditional treatment of diabetes. The administration of an aqueous extract of Scoparia dulcis at a dose of 200 mg/kg body weight significantly decreased the blood glucose with significant increase in plasma insulin level in streptozotocin diabetic rats at the end of 15 days treatment. The insulin secretagogue action of Scoparia dulcis plant extract (SPEt) was further investigated using isolated pancreatic islets from mice. SPEt at a dose of 10 microg/ml evoked 6.0 fold stimulation of insulin secretion from isolated islets indicating its insulin secretagogue activity. In addition the effect of SPEt on streptozotocin induced cell death and nitric oxide (NO) in terms of nitrite production were also examined. SPEt protected against streptozotocin- mediated cytotoxicity (88%) and NO production in rat insulinoma cell line (RINm5F). Above results suggest the glucose lowering effect of SPEt to be associated with potentiation of insulin release from pancreatic islets. Our results revealed the possible therapeutic value of Scoparia dulcis for the better control, management and prevention of diabetes mellitus progression.     

Effect of Coscinium fenestratum on hepatotoxicity in rats

Anti-hepatotoxic activity of methanol extract of Coscinium fenestratum stem (MEC) was investigated against carbon tetrachloride-induced hepatopathy in rats. Hepatotoxic rats were treated with MEC for a period of 90 days (60mg/kg body weight, daily, orally by intubation). Anti-hepatotoxic effect was studied by assaying the activities of serum marker enzymes like aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma glutamyl transpeptidase, lactate dehydrogenase etc. and glucose (6) phosphate dehydrogenase in liver. We also estimated the concentrations of total proteins, total lipids, triglycerides, phospholipids and cholesterol in serum, liver and kidney. The activities of all the marker enzymes registered a significant elevation in carbon tetrachloride-treated rats, which were significantly recovered towards an almost normal level in animals co-administered with MEC. Other biochemical changes induced by carbon tetrachloride too showed reliable signs of retrieving towards the normalcy. Histopathological analysis confirmed the biochemical investigations. This study unravels the anti-hepatotoxic activity of MEC.     

Fine needle aspiration of parathyroid lesions

OBJECTIVE: To assess the cytologic features of parathyroid lesions and to determine if it is possible to differentiate between parathyroid hyperplasia (PH) and parathyroid adenoma (PA) based on fine needle aspiration (FNA). STUDY DESIGN: FNAs of 14 parathyroid lesions were performed during intraoperative consultation. Alcohol-fixed, Papanicolaou-stained smears and air-dried Diff-Quik-stained smears were prepared in each case. Cytologic features were evaluated. RESULTS: All cases, PA and PH, showed numerous bare nuclei in the background. Ninety percent of PA contained microfollicular groups in addition to sheets and syncytia, while PH was arranged primarily in sheets and syncytia without microfollicles. Nuclear pleomorphism was seen in 33% of PA and absent from PH. CONCLUSION: Careful evaluation of cytologic features might help to differentiate between PA and PH on FNA.     

The PtdIns 3-Kinase/Akt Pathway Regulates Macrophage-Mediated ADCC against B Cell Lymphoma

Macrophages are important effectors in the clearance of antibody-coated tumor cells. However, the signaling pathways that regulate macrophage-induced ADCC are poorly defined. To understand the regulation of macrophage-mediated ADCC, we used human B cell lymphoma coated with Rituximab as the tumor target and murine macrophages primed with IFNγ as the effectors. Our data demonstrate that the PtdIns 3-kinase/Akt pathway is activated during macrophage-induced ADCC and that the inhibition of PtdIns 3-kinase results in the inhibition of macrophage-mediated cytotoxicity. Interestingly, downstream of PtdIns 3-kinase, expression of constitutively active Akt (Myr-Akt) in macrophages significantly enhanced their ability to mediate ADCC. Further analysis revealed that in this model, macrophage-mediated ADCC is dependent upon the release of nitric oxide (NO). However, the PtdIns 3-kinase/Akt pathway does not appear to regulate NO production. An examination of the role of the PtdIns 3-kinase/Akt pathway in regulating conjugate formation indicated that macrophages treated with an inhibitor of PtdIns 3-kinase fail to polarize the cytoskeleton at the synapse and show a significant reduction in the number of conjugates formed with tumor targets. Further, inhibition of PtdIns 3-kinase also reduced macrophage spreading on Rituximab-coated surfaces. On the other hand, Myr-Akt expressing macrophages displayed a significantly greater ability to form conjugates with tumor cells. Taken together, these findings illustrate that the PtdIns 3-kinase/Akt pathway plays a critical role in macrophage ADCC through its influence on conjugate formation between macrophages and antibody-coated tumor cells.     

Nuclear DNA content of Pongamia pinnata L. and genome size stability of in vitro-regenerated plantlets

Pongamia pinnata L. is a multipurpose versatile legume that is well known as a prospective feedstock biodiesel species. However, to date, there has been little genomic research aimed at the exploitation of the biotechnological potential of this species. Genetic characterization of any plant is a challenging task when there is no information about the genome size and organization of the species. Therefore, the genome size of P. pinnata was estimated by flow cytometry with respect to two standards (Zea mays and Pisum sativum), and compared with that of in vitro-raised plants (nodal segment, in vitro-rooted plantlets and acclimatized in vitro plants) to study the potential effect of somaclonal variation on genome size. This method can be used to support the establishment of true-to-type plants to encourage afforestation programs. Modified propidium iodide/hypotonic citrate buffer was used for isolation of the intact nuclei. The 2C DNA value of this species was estimated to be 2.51?±?0.01 pg. Statistically, there was no significant difference in the DNA content of the in vitro-grown plants and mother plant at α?=?0.05. As a result of the low genome size of P. pinnata, a species that has adapted itself to a wide range of edaphic and ecological condition, we can now proceed for its next generation sequencing and genomic diversity studies.     

A comparison of Zn2+- and Ca2+-triggered depolarization of liver mitochondria reveals no evidence of Zn2+-induced permeability transition

Intracellular Zn²⁺ toxicity is associated with mitochondrial dysfunction. Zn²⁺ depolarizes mitochondria in assays using isolated organelles as well as cultured cells. Some reports suggest that Zn²⁺-induced depolarization results from the opening of the mitochondrial permeability transition pore (mPTP). For a more detailed analysis of this relationship, we compared Zn²⁺-induced depolarization with the effects of Ca²⁺ in single isolated rat liver mitochondria monitored with the potentiometric probe rhodamine 123. Consistent with previous work, we found that relatively low levels of Ca²⁺ caused rapid, complete and irreversible loss of mitochondrial membrane potential, an effect that was diminished by classic inhibitors of mPT, including high Mg²⁺, ADP and cyclosporine A. Zn²⁺ also depolarized mitochondria, but only at relatively high concentrations. Furthermore Zn²⁺-induced depolarization was slower, partial and sometimes reversible, and was not affected by inhibitors of mPT. We also compared the effects of Ca²⁺ and Zn²⁺ in a calcein-retention assay. Consistent with the well-documented ability of Ca²⁺ to induce mPT, we found that it caused rapid and substantial loss of matrix calcein. In contrast, calcein remained in Zn²⁺-treated mitochondria. Considered together, our results suggest that Ca²⁺ and Zn²⁺ depolarize mitochondria by considerably different mechanisms, that opening of the mPTP is not a direct consequence of Zn²⁺-induced depolarization, and that Zn²⁺ is not a particularly potent mitochondrial inhibitor.