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Biomedical subjects

V M Doctor

Publications and source records attributed to V M Doctor.

At least 19 recordsLinked to original sources
PubMed2002

The effect of 6-aminohexanoic acid and fucoidan on the activation of glutamic plasminogen by streptokinase.

Studies were conducted on the effect of 6-aminohexanoic acid (6-AH) or fucoidan on the activation of glutamic plasminogen (glu-plg) by streptokinase using 0.05 mol/l Tris buffer containing a physiological concentration of NaCl. In contrast to the earlier reports where no NaCl was added to the buffer solution, addition of 6-AH enhanced the initial rate while the inhibition by fucoidan was not affected. Double reciprocal plots of the activation of glu-plg by streptokinase in the presence of 6-AH showed an increase in Vmax, but no change in Km. However, the addition of fucoidan showed a decrease in Vmax, but no change in Km. To determine whether the stimulatory effect of 6-AH was specifically directed towards glu-plg or streptokinase, the ratios of the initial rate of plasmin generation in the presence of 6-AH over the controls were plotted against the inverse of the volume fraction of glu-plg or streptokinase after serial dilutions. The results indicated that the dilutions of glu-plg, but not of streptokinase, influenced the ratios, suggesting an interaction of 6-AH with glu-plg. Similar experiments were conducted to determine the mechanism of inhibition of streptokinase by fucoidan. The results indicated that fucoidan was interacting with streptokinase, but not with glu-plg. Circular dichroism studies of glu-plg in the near-ultraviolet spectra (250-308 nm) showed that addition of 6-AH enhanced the spectra in the region around certain chromophores, which reflected conformational changes. On the contrary, the far-ultraviolet spectra were almost identical.

Aminocaproic Acid↗
PubMed1997

Interaction of fucoidan with proteases and inhibitors of coagulation and fibrinolysis.

The interactions of fucoidan with glutamic plasminogen (Glu-Plg), two-chain tissue plasminogen activator (t-PA), LMwt-urokinase, thrombin, and antithrombin III (AT-III) were investigated using fucoidan-sepharose affinity chromatography. The results showed 1) a high degree of affinity between fucoidan-sepharose and Glu-Plg; Lmwt-urokinase and thrombin while t-Pa and AT-III did not bind with fucoidan-sepharose. 2) The double reciprocal plot for the LMwt-urokinase activation of Glu-Plg showed that plasminogen activator inhibitor (PAI-1) inhibited this reaction in a noncompetitive manner and that the presence of fucoidan decreased Km for this interaction by 50% and increased Kcat by 30-fold, 3) The double reciprocal plot for the t-PA activation of Glu-Plg showed that PAI-1 inhibited this reaction in a competitive manner and that fucoidan in conjunction with 6-aminohexanoic acid (6-AH) increased Kcat for this interaction by 5-fold without affecting Km. 4) Fucoidan enhanced the interaction of thrombin with both AT-III and heparin cofactor II (HC-II) and it was more effective than unfractionated heparin of LMwt-heparin in enhancing the interaction of HC-II with thrombin.

Anticoagulants↗
PubMed1997

Comparison of the anticoagulant action of sulfated and phosphorylated polysaccharides.

Oat spelts xylan (OSX), fucoidan, kappa carrageenan and chondroitin sulfates A and C were sulfated using chlorosulfonic acid-pyridine complex while the first three were phosphorylated using methane sulfonic acid-phosphorous pentoxide mixture. The compounds were isolated as the sodium salts and their in vitro anticoagulant properties were determined by measuring the concentration of each compound required to double prothrombin time of pooled normal human plasma. The results of 31P-nmr spectroscopy showed that phosphorylation significantly increased the molecular weights of the polysaccharides by forming phosphodiester and diphosphodiester bonds. In general the anticoagulant properties of the sulfated polysaccharides were related to the % sulfate while the phosphorylated polysaccharides showed increases in anticoagulant properties which were related to the increase in the molecular weight and inversely related to the % phosphate. The mechanism of action of oat spelts xylan phosphate (OSXP) was studied using 125I-thrombin and normal human plasma. The results showed that at lower concentration of the OSXP, the complexation of 125I-thrombin with heparin cofactor-II(HC-II) was enhanced, while at higher concentration of the compound, the complexation with both antithrombin-III(AT-III) and HC-II was enhanced.

Anticoagulants↗
PubMed1995

Effect of fucoidan during activation of human plasminogen.

Fucoidan [sulfated poly (L-fucopyranose)] was compared with 6-aminohexanoic acid (6-AH) or CNBr-cleaved fibrinogen (CNBr-Fbg) alone or in combination in enhancing the activation of glutamic plasminogen (Glu-Plg) or lysine plasminogen (Lys-Plg) by two-chain tissue plasminogen activator (t-PA) or LMwt-urokinase or by streptokinase. Fucoidan enhanced the t-PA activation of Glu-Plg or Lys-Plg at Plg concentrations greater than 75nM, while stimulation by CNBr-Fbg of t-PA activation followed saturation kinetics of Michaelis-Menton. During t-PA activation of Glu-Plg, a high degree of synergism was observed between 6-AH and fucoidan while the enhancement by CNBr-Fbg was not influenced by fucoidan and was reversed by 6-AH. Fucoidan alone at higher concentrations was effective in enhancing the activation of Glu-Plg by urokinase while the combination of fucoidan and 6-AH showed additive effect in enhancing the activation of Lys-Plg. The activation of Glu-Plg by streptokinase was reversed by fucoidan in a manner similar to that reported for 6-AH. The results are interpreted to suggest that CNBr-Fbg and 6-AH compete with each other for the same lysine binding sites (LBS) on the Plg molecule while fucoidan acted synergistically with 6-AH in enhancing the t-PA activation of Glu-Plg by a different mechanism. The double reciprocal plot for the interaction of Glu-Plg and urokinase also showed a significantly higher affinity between the two in presence of fucoidan.

Amino Acid Sequence↗
PubMed1995

Fluorescence and circular dichroism studies during the interactions of sulfated polysaccharides with antithrombin III.

The changes in relative fluorescence of antithrombin III (AT-III) during its interaction with sulfated xylans were compared with that of sulfated glycosaminoglycans by measuring the ratio of the increase in fluorescence of AT-III in the presence of sulfated polysaccharide to the fluorescence of AT-III alone for various mass ratios. Interactions of corn cob xylan sulfate (CCXS) and sodium pentosan polysulfate (SP-54) with AT-III resulted in enhancements of relative fluorescence which were lower than commercial heparin. At mass ratios below 1, heparan sulfate and low molecular weight heparin (LMWH) gave increases in the relative fluorescence higher than that of commercial heparin, while highly sulfated semisynthetic chondroitin sulfates A and C gave much smaller increases. The relative fluorescence enhancements of AT-III by heparan sulfate, commercial heparin, LMWH and heparin derived pentasaccharide (HDP) increased with increasing mass ratios while the enhancements by CCXS, SP-54 and the highly sulfated chondroitin sulfates A and C were reversed at higher mass ratios. The estimated dissociation constants (kd) for the interaction of AT-III and the heparin-related compounds showed that heparin sulfate and LMWH gave the lowest kd values indicating a higher affinity for AT-III while commercial heparin and HDP gave higher kd values, indicating a lower affinity for AT-III. SP-54 gave a kd value lower than CCXS, indicating a greater affinity for AT-III. A comparison of the near ultraviolet (UV) circular dichroism (CD) spectrum of AT-III alone and during its interaction with oat spelts xylan sulfate (OSXS) showed enhancements of the two aromatic amino acid regions corresponding to phenylalanine and tryptophan.

Antithrombin III↗
PubMed1995

Detection of human papillomavirus (HPV) types in precancerous and cancerous lesions of cervix in Indian women: a preliminary report.

One hundred cervical tissues including 72 malignancies (68 squamous cell carcinomas, 3 adenocarcinomas, 1 neuro-endocrine carcinoma), 24 cases of CIN of various grades and 4 normals were examined for the presence of Human Papilloma virus (HPV) types by non isotopic in-situ hybridisation. Biotinylated probes to HPV types 16 and 18 were used in all the cases and 31 and 33 in 15 squamous Carcinomas. HPV DNA sequences were detected in 55/72 (76.4%) of the malignant lesions, of which among squamous Carcinomas. HPV 16 alone was present in 12 of 68 cases (17.64%) and type 18 in 15 of 68 cases (22.0%). 20/68 (29.4%) showed both types 16 and 18. Of the 15 cases examined for types 31 and 33.5 cases showed presence of both types. All three adenocarcinomas were negative for HPV 16, but positive for HPV 18. The solitary case of Neuroendocrine Carcinoma showed only HPV 18. Of the 24 CINS, type 16 was detected in 7/24 cases (29.1%) type 18 in 2/24 (8.3%) cases and both types in 1/24 (4.1%). None of the normal cases showed positive signals for HPV. The overall results show a slight preponderance of HPV 18 in this group of carcinoma of cervix studied and correlate with poor differentiation and greater aggressive behaviour of cervical cancer which is the most common type of cancer among women in this country.

DNA, Neoplasm↗
PubMed1992

Mixed tumour of salivary gland type of the male breast.

Benign breast tumours with a mixed cartilaginous and epithelial component are distinctly rare as evident from the literature. A case of Mixed Tumour of the breast presenting pre-operatively as a hard mass in a 65 year old male is reported. Histologically, it was composed of a mixture of benign cartilage, myoepithelial cells, tubules and a myxoid stroma in fat. A brief review of cartilage bearing lesions and mixed tumour in the mammary region is discussed.

Adenoma, Pleomorphic↗
PubMed1991

Anticoagulant properties of semisynthetic polysaccharide sulfates.

Several naturally occurring polysaccharides were purified and subsequently sulfated by chlorosulfonic acid-pyridine complex. These were isolated as the sodium salt and further purified by ECTEOLA cellulose chromatography. Anticoagulant properties of the sulfated polysaccharides were compared with commercial heparin by measuring their in vitro effects on activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) using pooled normal human plasma. In general, all the compounds exhibited antithrombic (anti-TT) properties similar to heparin but were less effective than heparin in inhibiting APTT or PT. The in vivo anticoagulant properties were also compared with commercial heparin by injecting rats a single intraperitoneal dose and measuring plasma APTT at 2, 4 and 6 hour intervals. All of the compounds including heparin increased APTT significantly at 2 hours and then gradually returned to near normal value after 6 hours. Larchwood xylan sulfate was almost as active as heparin in inhibiting APTT while the rest of the compounds were less active. Toxicological studies using rats showed wide variations in the LD50 of various compounds. Sulfated xylan and heparin were least toxic while sulfated polysaccharide of locust bean was most toxic. For most of the compounds the LD50 was 5-100 fold higher than the effective dosage.

Animals↗
PubMed1991

Extrarenal Wilm's tumour. A case report and review of literature.

An extrarenal Wilms' tumour exhibiting an unusual histology is reported in the inguinal region of a 3 year old girl. The tumour presents a tubulopapillary pattern associated with foci of nephroblastomatosis, a morphologic variant not previously described in any of the extrarenal Wilms' tumour. The unusual histologic picture enhances the difficulty in histogenetic based precise diagnosis. This case represents the 8th EWT of the inguinal region.

Child, Preschool↗
PubMed1990

Mechanism of potentiation of antithrombin III and heparin cofactor II inhibition by sulfated xylans.

Kinetic analyses of antithrombin III (AT-III)-thrombin or heparin cofactor II (HC-II)-thrombin or AT-III-factor Xa interactions were carried out in the absence or in the presence of one of the sulfated xylans or unfractionated heparin or low molecular weight (LMW) heparin utilizing chromogenic substrates. These studies demonstrated that under pseudo first order conditions the inhibitions were proportional to the AT-III or HC-II concentrations used and the apparent second order rate constants determined from the slopes of the pseudo first order plots of log of thrombin or Xa remaining as a function of time were significantly elevated in presence of the sulfated compounds. On a molar basis oat spelts xylan sulfate was the most effective compound in accelerating the rate of thrombin-AT-III interaction followed by commercial heparin while the latter was most effective in accelerating the rate of thrombin-HC-II interaction. Heparin and LMW heparin were more effective in that order in accelerating the rate of Xa-AT-III interaction while oat spelts xylan sulfate, corn cob xylan sulfate, SP-54 were less effective than the heparins in that order. Studies were also conducted on the concentrations of the sulfated compounds required to inhibit by 50% the thrombin activity by AT-III or HC-II or that required to inhibit by 50% the factor Xa activity by AT-III. The results showed an inverse relationship between the increase in the rate of acceleration by the sulfated compound with the decrease in the amount required for 50% inhibition. SDS-polyacrylamide gel study of the reaction mixture containing thrombin, AT-III or HC-II along with heparin or oat spelts xylan sulfate showed that like heparin, oat spelts xylan sulfate potentiated the formation of thrombin-AT-III or thrombin-HC-II complexes which were stable in presence of denaturing or reducing agents. Chemical modification of arginine or lysine of AT-III significantly lowered its potentiation of thrombin or Xa inhibition by oat spelts xylan sulfate.

Amino Acid Sequence↗
PubMed1990

Immunocytochemical localization of follicle stimulating hormone in normal human stomach.

Immunoreactive follicle-stimulating hormone (IR-FSH) is detected in sections of formalin-fixed and paraffin-embedded gastric mucosal tissue of normal men, using the immunoperoxidase staining technique and specific antisera to hFSH (NIDDK, NIH). Positive staining for IR-FSH was detected in the parietal cells lining the gastric glands of the intermediate zone. The staining was intracytoplasmic and distributed throughout the cytoplasm. IR-FSH was also found to be present in the basal part of the foveolar epithelium. Stromal tissue and nuclei were devoid of the stain. The zymogen cells in the deeper region of the mucosa did not show any detectable staining for IR-FSH. The presence of IR-FSH in gastric mucosa was also detected by radioimmunoassay. Gel chromatography of the gastric tissue extract showed a single peak of FSH immunoreactivity that coeluted with the 125I-labeled highly purified FSH preparation (NIDDK, NIH). Furthermore, the FSH in the pituitary tissue extract had a chromatographic profile similar to that of IR-FSH from gastric tissue, and 125I-FSH labeled highly purified FSH, indicating a close resemblance in their molecular sizes. These results demonstrate that IR-FSH is present in the normal human gastric mucosa. The role of this regulatory petpide in gastric tissue, if any, needs to be investigated.

Chromatography↗
PubMed1990

Immunocytochemical localisation of follicle stimulating hormone (FSH) in normal, benign and malignant human prostates.

Immunocytochemical localisation of follicle stimulating hormone (FSH) was carried out in normal, benign and malignant human prostates by indirect immunoperoxidase technique. Positive staining was observed in the epithelial cells of all the three categories, while the stromal cells showed a weakly positive reaction in a few specimens. The brown reaction product was dispersed in the cytoplasm of the epithelial cells. These observations demonstrate the presence of immunoreactive FSH-like peptide in human prostate. The significance of FSH in the aetiopathology of prostatic disorders is discussed.

Adolescent↗
PubMed1990

Immunoreactive-FSH in human normal gastric mucosa.

Using indirect immuno-peroxidase staining technique, localization of immunoreactive follicle-stimulating hormone (IR-FSH) is demonstrated in the cytoplasm of the epithelial cells of normal human stomach. In view of their triangular shape and central nucleus and their predominance in the intermediate glands of the gastric mucosa, these cells are identified as parietal cells. The stromal tissue is devoid of staining reaction.

Cytoplasm↗
PubMed1987

Mechanism of potentiation of antithrombin III [AT-III] inhibition by sulfated xylans.

Anticoagulant properties of three sulfated compounds prepared from xylans isolated from corn cobs, larchwood and oatspelts were compared with heparin and sodium pentosan polysulfate (SP-54) by studying their effects on activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) using pooled normal human plasma. These compounds were more effective than SP-54 in delaying coagulation by all the three procedures while oatspelts xylan sulfate was as effective as heparin in inhibiting APTT and PT and more effective than heparin in inhibiting TT on a molar basis. The sulfated xylans were more effective than heparin or SP-54 in potentiating the AT-III inhibition of amidolysis of H-D-Phe-Pip-Arg-pNa (S-2238) by thrombin (IIa) or amidolysis of Bz-Ile-Glu-Gly-Arg-pNa (S-2222) by Xa. Study of the high affinity binding of the xylan sulfates to AT-III-Sepharose column showed that the amount of the xylan sulfate recovered in the eluates from this peak was greatly increased with an increase in molecular weight (MW). A buffered mixture of IIa, AT-III and dansylarginine N-(3-ethyl-1,5-pentanediyl) amide (DAPA) was used to study the inactivation of IIa by AT-III. Larchwood xylan sulfate (2-10 micrograms) was found to accelerate this inactivation which was neutralized by human platelet factor 4 (PF4). The results also suggested an interaction between larchwood xylan sulfate and IIa which may potentiate an interaction between AT-III and IIa.

Anticoagulants↗
PubMed1987

Mechanism of anticoagulant action by protein inhibitors from bovine testes and salmon sperm.

A protein inhibitor was isolated from commercial preparations of salmon sperm and its physical and anticoagulant properties were compared with an inhibitor isolated earlier from commercial preparation of bovine testicular hyaluronidase. The inhibitor from bovine source was heat and acid labile and had a molecular weight of approximately equal to 35000 while the one from salmon sperm had a molecular weight of approximately equal to 5700 and was stable to heat and acid. To determine the mechanism of the inhibitory effect, a system of purified components consisting of isolated prothrombin, Factor Xa, Factor Va, Ca++, and vesicles of phosphatidylcholine (PCPS, 25% PS) was used. Included also was dansylarginine N- (3-ethyl-1,5-pentanedidyl) amide (DAPA) which binds newly formed thrombin and yields the time course of prothrombin conversion by virtue of enhanced fluorescence of the DAPA - thrombin complex. The inhibitor of bovine testes was effective only when PCPS was the limiting component suggesting that its action was directed against the phospholipid component of the prothrombinase complex. The inhibitor from salmon sperm was found to lower the rate of conversion of prothrombin to thrombin in an in vitro system where thrombin generation was measured by its action on the chromogenic substrate H-D-Phe-Pip-Arg-pNa (S-2238). It inhibited the conversion of Factor X to Xa and also the the amidolytic cleavage by Factor Xa of chromogenic substrate N-Benz-Ile-Glu-Gly-Arg-pNa (S-2222).

Animals↗