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Biomedical subjects

A Raman

Publications and source records attributed to A Raman.

At least 19 recordsLinked to original sources
PubMed2003

In vitro evaluation of Bacopa monniera on anti-Helicobacter pylori activity and accumulation of prostaglandins.

Bacopa monniera is an Indian tratidional medicine widely used to improve intellectual functions. Earlier, we had reported the prophylactic and curative effects of standardized extract of Bacopa monniera (BME) in various gastric ulcer models. The effect was due to augmentation of the defensive mucosal factors like increase in mucin secretion, life span of mucosal cells and gastric antioxidant effect rather than on the offensive acid-pepsin secretion. The present study includes evaluation of standardized BME (bacoside A content--35.5 +/- 0.9) on other contributing factors towards ulcerogenesis. BME in the dose of 1000 microg/ml showed anti-Helicobacter pylori activity in vitrol and in the dose of 10 microg/ml increased in vitro of prostanoids (PGE and PGI2) in human colonic mucosal incubates. It may be concluded that these factors may contribute to antiulcerogenic activity of BME.

Anti-Infective Agents↗
PubMed2003

Oviposition by introduced Ophelimus eucalypti (Hymenoptera: Eulophidae) and morphogenesis of female-induced galls on Eucalyptus saligna(Myrtaceae) in New Zealand.

An Australian gall-inducing eulophid, Ophelimus eucalypti (Gahan) was first recorded on the foliage of Eucalyptus botryoides after it invaded New Zealand in 1987. It has spread throughout the eucalypt plantations in the North Island and in the northern parts of the South Island affecting several species of Eucalyptus in the section Transversaria (subgenus Symphyomyrtus). Because gall-inducing insects usually have extremely narrow host ranges, O. eucalypti that induces galls on E. saligna and E. botryoides is currently recognized as a biotype, O. eucalypti(Transversaria). Heavily galled leaves abscise from the plant. Repeated defoliation led to widespread die-back of susceptible eucalypt species in the 1990s. Female larvae of O. eucalypti induce circular, protruding galls on the leaves of E. botryoides and E. saligna, whereas the males induce pit galls on the same species. The biology of O. eucalypti females and the development of their galls are described. Adult female O. eucalypti antennate the leaf surface before inserting the ovipositor (otherwise concealed within the metasomal apex) into the young host leaf. The egg is inserted at approximately 45 degrees and discharged between differentiating palisade cells. Callus-type cells surround the egg chamber, but cytologically specialized nutritive cells appear once the egg hatches and the larva begins to feed. The gall also differentiates a multi-layered sclerenchymatous tissue around the nutritive tissue. After feeding for many months, the larva pupates and the active nutritive tissue degenerates. The adult wasp emerges after cutting an exit hole through to the outside of the gall. Abscission of heavily galled leaves results in widespread defoliation and loss of growth and vigour in susceptible trees in New Zealand.

Animals↗
PubMed2001

Potential benefit of lymphadenectomy for the treatment of node-negative locally advanced uterine cancers.

OBJECTIVE: The aim of this study was to examine the outcomes in patients with high-risk Stage I endometrial cancers surgically staged by complete pelvic and para-aortic lymphadenectomy, with negative nodes, and treated with postoperative brachytherapy. METHODS: From the database of patients treated for Stage I endometrial cancer, 23 patients were identified with either >50% myometrial invasion or grade 3 histology treated with total abdominal hysterectomy, bilateral salpingo-oophorectomy, and pelvic and para-aortic lymphadenectomy. All patients had no pathologic evidence of disease in the lymph nodes. These patients were then treated with brachytherapy and followed for treatment and cost outcomes. A comparison was made of the cost of treatment between brachytherapy and external beam radiation. RESULTS: All 23 patients with either grade 3 tumor or greater than 50% myometrial invasion were treated with total abdominal hysterectomy with lymphadenectomy followed by brachytherapy for lesions that did not extend outside the uterine specimen. For all patients in this series, there were no recurrences in the follow-up period (median 25 months). This regimen is more cost efficient and spares the patient from possible complications related to whole pelvic radiation, at an average cost savings of $4100. CONCLUSION: Women undergoing hysterectomy for endometrial adenocarcinoma with high-risk node-negative disease confined to the uterus can be safely treated with brachytherapy, at a substantial cost savings, without compromising survival.

Adenocarcinoma↗
PubMed2001

Lyoluminescence characteristics of trehalose dihydrate.

Lyoluminescence (LL) of trehalose dihydrate showed a linear gamma ray sensitivity in the dose range 0.1-5 x 10(2) Gy. At increased sample weight dissolved, the LL/mg showed a reduction when the microcontroller based integrated measurement system was used. The LL/mg was found to be independent of the sample weight when the instantaneous peak output observed by the electrometer amplifier on dissolution of the phosphor was taken as a measure of LL yield. The LL spectral measurement of trehalose dihydrate in luminol solution (LL sensitizer) confirms an energy transfer from the radiation induced free radicals to luminol molecule to produce light.

Journal Article↗
PubMed2001

In vitro keratinocyte antiproliferant effect of Centella asiatica extract and triterpenoid saponins.

Psoriasis is a hyperproliferative skin disorder estimated to be present in 1-3% of most populations. Conventional therapy using corticosteroids, Vitamin D analogs and cytotoxic agents eg psoralens is associated with low success rate and many side effects. Traditional plant remedies may provide leads for new treatments. A rapid-throughput, in vitro bioassay has been utilised to examine plants for inhibitory effects on the growth of SVK-14 keratinocytes. Centella asiatica, a reputed anti-psoriatic herb, has been compared against the psoralen-containing seeds of Psoralea corylifolia and the synthetic anti-psoriatic agent dithranol (anthralin). Aqueous extracts of Psoralea corylifolia and Centella asiatica inhibited keratinocyte replication with IC50 values of 18.4 +/- 0.6 microg/ml and 209.9 +/- 9.8 mg/ml respectively prior to treatment with polyvinylpolypyrrolidone (PVPP) and 36.3 +/- 3.3 mg/ml and 238.0 +/- 2.5 mg/ml respectively after PVPP treatment of the extracts. The effect produced by C. asiatica is thus unlikely to be due to phenolic compounds. It may, however, be due to its two constituent triterpenoid glycosides madecassoside and asiaticoside which had IC50 values of 8.6 +/- 0.6 microM respectively. These values were comparable to their concentrations in the crude extract and to the IC50 of dithranol (5.1 +/- 0.4 microM). These results suggest that the potential use of C. asiatica extracts as a topical anti-psoriatic agent is worthy of further investigation.

Anti-Infective Agents↗
PubMed2001

In vitro effect of fenugreek extracts on intestinal sodium-dependent glucose uptake and hepatic glycogen phosphorylase A.

Fenugreek (Trigonella foenum-graecum L. seed) is a food with traditional medicinal use in diabetes. Beneficial effects have been demonstrated in diabetic animals and both insulin-dependent and non-insulin-dependent diabetic subjects. Effects of a lipid extract A, crude ethanolic extract B, further sub-fractions of B (saponin-free C, saponin D and sapogenin E) and a gum fibre fraction F on intestinal sodium-dependent glucose uptake were investigated in vitro using rabbit intestinal brush border membrane vesicles. All fractions except A inhibited glucose-uptake at 0.33 and/or 3.3 mg/mL (p < 0.001). Greatest inhibition was observed with fractions D and E. Diosgenin and trigonelline (compounds reported in fenugreek) also inhibited glucose-uptake (IC50 values approximately 3 mg/ml, equivalent to 8 mM and 19 mM respectively) but did not account for the activity of the crude extracts. Fenugreek extracts had no effect on basal levels of glycogen phosphorylase a (HGPa) activity in rat hepatocyte suspensions. However fractions C and E caused a marginal but statistically significant inhibition (18.9 and 15.1% respectively, p < 0.05) of glucagon induction of this enzyme suggesting a glucagon-antagonist effect. Diosgenin (1.65 mg/ml; 4 mM) inhibited glucagon-induced HGPa activity by 20% (p < 0.05), and was more effective than trigonelline (non significant inhibition of 9.4% at 1.65 mg/ml, 10 mM).

Animals↗
PubMed2001

Primary papillary carcinoma in a thyroglossal cyst.

Papillary carcinoma arising in a thyroglossal cyst is rare. There is controversy regarding optimum management. We report a case managed by Sistrunk's procedure and external radiotherapy and review the literature on the subject.

Adult↗
PubMed2000

A relation between the principal axes of inertia and ligand binding.

The principal axes of inertia are eigenvectors that can be calculated for any rigid body. We report studies of the position of the principal axes in crystallographically solved protein molecules. We find with high frequency that at least one principal axis penetrates the surface of the respective protein in a region used for ligand binding. In antibody variable regions, an axis goes through the third hypervariable loop of the heavy chain. In major histocompatibility complex proteins, an axis goes through the peptide-binding groove. In protein-protein heterodimers, a principal axis of one subunit will often penetrate the interface formed with the other subunit. In many of these protein-protein complexes, the axis specifically intersects residues known to be critical for molecular recognition.

Algorithms↗
PubMed1999

Antioxidant action and potential antidiabetic properties of an isoflavonoid-containing soyabean phytochemical extract (SPE).

The potential role of oestrogenic agents, antioxidants and intestinal glucose-uptake inhibitors in the treatment of diabetes is briefly reviewed. Reports in the literature suggest that oestrogen replacement therapy may favourably modulate glucose homeostasis. A soya phytochemical extract (SPE) containing the isoflavone phytoestrogens genistein and daidzein (mostly in their glycone forms as genistin and daidzin) was investigated as an antioxidant and modulator of intestinal glucose-transport. In the present study, SPE was found to protect against glucose-induced oxidation of human low density lipoproteins (LDL) in vitro. Equol (a gut bacterial metabolite of daidzein) was a more effective antioxidant than daidzein or genistein in this system and was of similar antioxidant potency to the dietary flavonols quercetin and kaempferol and to the endogenous antioxidant 17beta-oestradiol. SPE was found to be an inhibitor of glucose uptake into rabbit intestinal brush border membrane vesicles in vitro, though of weaker potency than the classical sodium dependent glucose transporter (SGLT) inhibitor, phlorizin. Thus SPE displays a range of properties which may be of benefit in diabetes, namely as an oestrogenic agent, an inhibitor of intestinal glucose-uptake and a preventive agent for glucose-induced lipid peroxidation.

Animals↗
PubMed1999

Sulphorhodamine B assay for measuring proliferation of a pigmented melanocyte cell line and its application to the evaluation of crude drugs used in the treatment of vitiligo.

A rapid 96-well plate assay using sulphorhodamine B (SRB) protein stain for cell number has been adopted to screen herbs used in traditional treatments of vitiligo for substances capable of stimulating melanocyte proliferation. Its applicability to melan-a cells, a mouse pigmented cell line, has been validated. SRB assay produced good linearity up to 11 x 10(4) cells/well and interference by melanin present in the cells accounted for less than 10% of the total optical density readings. The intra-assay variation was small but interassay variation was marked. For better assay precision, it is recommended that the results to be compared should be performed on the same day and controls should be plated in the same experiment, ideally in the same plate. Optimum conditions for exponential melan-a cell growth were established: viz. initial plating density (3-8 x 10(3) cells/well), incubation period (4 days) and foetal bovine serum concentration (5%). Under these conditions cells were responsive to the mitogen tetradecanoyl phorbol acetate (TPA). Out of 28 herbal extracts screened in this assay, significant stimulation (P < 0.05) of melanocyte proliferation was observed, in the absence of TPA, using aqueous extracts of Astragalus membranaceous root, Citrus reticulata peel, Dictamnus dasycarpus root bark. Ophiopogon japonicus root, Poria cocos sclerotium and Tribulus terrestris fruit.

Animals↗
PubMed1999

Lipoxygenase inhibitors in the seeds of Aframomum danielli K. Schum (Zingiberaceae).

Alcohol and petrol extracts of the seeds of Aframomum danielli inhibit the soya 5-lipoxygenase enzyme and thus may show antiinflammatory activity. Compounds isolated from the active fractions were shown to be long chain polyprenyl benzoquinone derivatives. Phytylplastoquinone was isolated from the petrol extract and plastoquinone-7 (heptaplastoquinone) from the alcohol extract. The presence of these two known benzoquinones in A. danielli and their ability to inhibit 5-lipoxygenase are reported here for the first time.

Chromatography, Thin Layer↗
PubMed1999

Stimulation of mouse melanocyte proliferation by Piper nigrum fruit extract and its main alkaloid, piperine.

During a herbal screening programme to find potential repigmenting agents for the treatment of vitiligo, Piper nigrum L. fruit (black pepper) extract was found to possess growth-stimulatory activity towards cultured melanocytes. Its aqueous extract at 0.1 mg/ml was observed to cause nearly 300% stimulation of the growth of a cultured mouse melanocyte line, melan-a, in 8 days (p < 0.01). Piperine (1-piperoylpiperidine), the main alkaloid from Piper nigrum fruit, also significantly stimulated melan-a cell growth. Both Piper nigrum extract and piperine induced morphological alterations in melan-a cells, with more and longer dendrites observed. The augmentation of growth by piperine was effectively inhibited by RO-31-8220, a selective protein kinase C (PKC) inhibitor, suggesting that PKC signalling is involved in its activity. This is the first full report on such an activity of black pepper and piperine.

Alkaloids↗
PubMed1999

Gymnema sylvestre stimulates insulin release in vitro by increased membrane permeability.

To determine whether extracts of Gymnema sylvestre may have therapeutic potential for the treatment of non-insulin-dependent diabetes mellitus (NIDDM), we examined the effects of an alcoholic extract of G. sylvestre (GS4) on insulin secretion from rat islets of Langerhans and several pancreatic beta-cell lines. GS4 stimulated insulin release from HIT-T15, MIN6 and RINm5F beta-cells and from islets in the absence of any other stimulus, and GS4-stimulated insulin secretion was inhibited in the presence of 1 mM EGTA. Blockade of voltage-operated Ca(2+) channels with 10 microM isradipine did not significantly affect GS4-induced secretion, and insulin release in response to GS4 was independent of incubation temperature. Examination of islet and beta-cell integrity after exposure to GS4, by trypan blue exclusion, indicated that concentrations of GS4 that stimulated insulin secretion also caused increased uptake of dye. Two gymnemic acid-enriched fractions of GS4, obtained by size exclusion and silica gel chromatography, also caused increases in insulin secretion concomitant with increased trypan blue uptake. These results confirm the stimulatory effects of G. sylvestre on insulin release, but indicate that GS4 acts by increasing cell permeability, rather than by stimulating exocytosis by regulated pathways. Thus the suitability of GS4 as a potential novel treatment for NIDDM can not be assessed by direct measurements of beta-cell function in vitro.

Animals↗
PubMed1996

Investigation of the effect of Angelica sinensis root extract on the proliferation of melanocytes in culture.

Aqueous extracts of Angelica sinensis root, a herb commonly used in the treatment of vitiligo in Traditional Chinese Medicine, were tested for their activity on mouse melanocyte proliferation in culture. At concentrations of 0.5-2500 micrograms/ml, these extracts were not able to stimulate melanocyte cell division. On the contrary, they exerted a general cytotoxicity to the cells at higher concentrations. Cytotoxicity was reduced by prior treatment of the extract with polyvinylpolypyrrolidone, which was shown by thin layer chromatography to reduce the coumarin content.

Animals↗
PubMed1995

Antimicrobial effects of tea-tree oil and its major components on Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes.

Major components of two tea-tree oil samples were identified using thin layer and gas-liquid chromatography (TLC and GLC). Using a TLC-bioautographic technique, the tea-tree oils, terpinen-4-ol, alpha-terpineol and alpha-pinene were found to be active against Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes whereas cineole was inactive against these organisms. The MIC values of the three active compounds increased in the order alpha-terpineol < terpinen-4-ol < alpha-pinene for all three micro-organisms. MIC values of the tea-tree oils and terpinen-4-ol were lower for P. acnes than for the two staphylococci. This study supports the use of tea-tree oil in the treatment of acne, and demonstrates that terpinen-4-ol is not the sole active constituent of the oil.

Anti-Infective Agents, Local↗
PubMed1992

Construction of Saccharomyces cerevisiae strains that accumulate relatively low concentrations of trehalose, and their application in testing the contribution of the disaccharide to stress tolerance.

Genetically related diploid strains of Saccharomyces cerevisiae that accumulate varied amounts of trehalose during starvation for nitrogen have been constructed. Strains that produced greater than 5% trehalose (dry cell weight) were more tolerant of thermal, or freeze-thaw stresses than strains that produced less than 4% trehalose. Thus trehalose appears to play a role in stress tolerance of yeast. The significance of these results is that, for the first time, a series of related, unmutated strains have been used to test the effect of trehalose on thermotolerance. Previous studies employed either heat shock treatment, or mutated strains to provide trehalose variations, and as such the contribution of the disaccharide to stress tolerance could not necessarily be separated from other factors such as heat shock proteins.

Hot Temperature↗