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D Mandal

Publications and source records attributed to D Mandal.

At least 19 recordsLinked to original sources
PubMed2000

Leishmania plasma membrane Mg2+-ATPase is a H+/K+-antiporter involved in glucose symport. Studies with sealed ghosts and vesicles of opposite polarity.

Experiments from other laboratories conducted with Leishmania donovani promastigote cells had earlier indicated that the plasma membrane Mg2+-ATPase of the parasite is an extrusion pump for H+. Taking advantage of the pellicular microtubular structure of the plasma membrane of the organism, we report procedures for obtaining sealed ghost and sealed everted vesicle of defined polarity. Rapid influx of H+ into everted vesicles was found to be dependent on the simultaneous presence of ATP (1 mm) and Mg2+ (1 mm). Excellent correspondence between rate of H+ entry and the enzyme activity clearly demonstrated the Mg2+-ATPase to be a true H+ pump. H+ entry into everted vesicle was strongly inhibited by SCH28080 (IC50 = approximately 40 microm) and by omeprazole (IC50 = approximately 50 microm), both of which are characteristic inhibitors of mammalian gastric H+,K+-ATPase. H+ influx was completely insensitive to ouabain (250 microm), the typical inhibitor of Na+,K+-ATPase. Mg2+-ATPase activity could be partially stimulated with K+ (20 mm) that was inhibitable (>85%) with SCH28080 (50 microm). ATP-dependent rapid efflux of 86Rb+ from preloaded vesicles was completely inhibited by preincubation with omeprazole (150 microm) and by 5,5'-dithiobis-(2-nitrobenzoic acid) (1 mm), an inhibitor of the enzyme. Assuming Rb+ to be a true surrogate for K+, an ATP-dependent, electroneutral stoichiometric exchange of H+ and K+(1:1) was established. Rapid and 10-fold active accumulation of [U-(14)C]2-deoxyglucose in sealed ghosts could be observed when an artificial pH gradient (interior alkaline) was imposed. Rapid efflux of [U-(14)C]d-glucose from preloaded everted vesicles could also be initiated by activating the enzyme, with ATP. Taken together, the plasma membrane Mg2+-ATPase has been identified as an electroneutral H+/K+ antiporter with some properties reminiscent of the gastric H+,K+-ATPase. This enzyme is possibly involved in active accumulation of glucose via a H+-glucose symport system and in K+ accumulation.

Adenosine Triphosphate↗
PubMed2000

Manganese selectivity of pmr1, the yeast secretory pathway ion pump, is defined by residue gln783 in transmembrane segment 6. Residue Asp778 is essential for cation transport.

We have solubilized and purified the histidine-tagged yeast secretory pathway/Golgi ion pump Pmr1 to near homogeneity in one step, using nickel affinity chromatography. The purified pump demonstrates both Ca(2+)- and Mn(2+)-dependent ATP hydrolysis and phosphoenzyme intermediate formation in forward (ATP) and reverse (P(i)) directions. This preparation has allowed us to examine, in detail, the properties of mutations D778A and Q783A in transmembrane segment M6 of Pmr1. In phenotypic screens of Ca(2+) chelator and Mn(2+) toxicity reported separately (Wei, Y., Chen, J., Rosas, G., Tompkins, D.A., Holt, P.A., and Rao, R. (2000) J. Biol. Chem. 275, XXXX-XXXX), D778A was a loss-of-function mutant apparently defective for transport of both Ca(2+) and Mn(2+), whereas mutant Q783A displayed a differential sensitivity consistent with the selective loss of Mn(2+) transport. We show that mutant D778A is devoid of cation-dependent ATP hydrolytic activity and phosphoenzyme formation from ATP. However, reverse phosphorylation from P(i) is preserved but is insensitive to inhibition by Ca(2+) or Mn(2+) ions, which is evidence for a specific inability to bind cations in this mutant. We also show that Ca(2+) can activate ATP hydrolysis in the purified Q783A mutant, with a half-maximal concentration of 0.06 micrometer, essentially identical to that of wild type (0.07 micrometer). Mn(2+) activation of ATP hydrolysis was half-maximal at 0.02 micrometer in wild type, establishing a normal selectivity profile of Mn(2+) > Ca(2+). Strikingly, Mn(2+)-ATPase in the Q783A mutant was nearly abolished, even at concentrations of up to 10 micrometer. These results were confirmed in assays of phosphoenzyme intermediates. Molecular modeling of the packing between helices M4 and M6 suggests that residue Gln(783) in M6 may form a critical hydrophobic interaction with Val(335) in M4, such that the Ala substitution modifies the packing or tilt of the helices and thus the ion pore. The data emphasize the critical role of transmembrane segment M6 in defining the cation binding pocket of P-type ATPases.

ATP-Binding Cassette Transporters↗
PubMed2000

Cervical cytology screening for sexually-active teenagers.

Our aim was to determine the value of cervical cytology for sexually-active teenagers attending genitourinary medicine (GUM) clinics. This is a retrospective review of 57,093 women who had cervical cytology reported at the Royal Bolton Hospital (RBH) during the period 1 April 1994 to 31 March 1996. The results were subdivided into 2 age groups; < or = 19 years and > or = 20 years. Cervical cytology abnormalities within each age group were analysed and compared with the national figures for cervical cytology screening. The results were also subdivided according to their source of referral; general practitioners (GP), GUM and gynaecology. The data from each group were analysed in the same manner as before. The results of the cervical cytology screening from the RBH for major cytological abnormalities (moderate dyskaryosis and above), for the 2 age groups, were comparable and not significantly different (2.1% for each age group, P=0.909) and these figures were within the range of the national figures for cervical cytology screening (1.1%-3.4%). Subdivision of the data by source of referral demonstrated that the percentage of major abnormalities in smears performed at GUM clinics was higher than the national figure for all age groups (41/1000 for the younger age group and 37/1000 for the older age group, 12/1000 for the national figures). In conclusion, cervical cytology screening should be offered to sexually-active teenagers attending GUM clinics.

Adolescent↗
PubMed1998

Low HIV and high STD among commercial sex workers in a brothel in Bangladesh: scope for prevention of larger epidemic.

The present study documents the first systematic assessment of a brothel in Bangladesh in terms of sexually transmitted disease (STD) and human immunodeficiency virus (HIV). A cross sectional study was undertaken on brothel-based commercial sex workers (CSWs) selected systematic random sampling to assess the prevalence of STDs and HIV among CSWs in a brothel setting. Two hundred and ninety-six CSWs were selected from a brothel with a population of 593 women. Following informed consent, endocervical and blood samples were obtained for the diagnosis of genital chlamydia, gonorrhoea, HIV and syphilis respectively. In addition, another 170 consecutive blood samples were collected from the total CSW population for HIV tests. All blood samples for HIV testing were made anonymous by removing patient identifiers before testing. Endocervical specimens were tested by polymerase chain reaction (PCR) for the diagnosis of genital chlamydia and gonorrhoea. Syphilis and HIV infections were diagnosed by serology. One hundred and sixty-nine (57.1%) of the women were Treponema pallidum haemagglutination (TPHA)-positive, 20 (6.8%) of the women were Venereal Disease Research Laboratory (VDRL)-positive at a greater than 1:8 dilution. Eighty-two (28%) of the women were found to be infected either by gonorrhoea or chlamydia. No HIV antibody was found in any of the 466 blood samples. A high prevalence of STDs and low prevalence of HIV in the CSWs in Bangladesh suggest potential for the rapid spread of HIV once it is introduced in this high-risk population. The opportunity to control STD and HIV infection in this population should not be missed, in order to prevent a large epidemic in the future.

Bangladesh↗
PubMed1997

The plasma-membrane Ca2+-ATPase of Leishmania donovani is an extrusion pump for Ca2+.

Controlled exposure of Leishmania donovani promastigotes to hypotonic shock results in the formation of deflagellated unsealed ghosts of original polarity that largely retain the pellicular microtubular structure associated with plasma membrane of the parasite. Gentle shearing followed by suspension of the purified membrane in appropriate isotonic buffer containing Mg2+ (4mM) results in the formation of sealed everted vesicles. The presence of Mg2+ (4 mM) appears to be essential for efficient sealing and also to prevent leakiness. ATP-dependent Ca2+ accumulation can be demonstrated in these vesicles Km values for Ca2+ and ATP were 125 nM and 0.8 mM respectively. The accumulated Ca2+ reaches a concentration of 1.1 mM. Ca2+ uptake is completely inhibited by vanadate (40 microM) and several thiol-modifying agents. Using 5,5'-dithiobis-(2-nitrobenzoic acid) as the modifying agent, an excellent correlation between loss of enzyme activity and transport capability and their parallel regeneration in the presence of 2 mM dithiothreitol was demonstrated. Using 2'.7-bis(carboxyethyl)-5(6)-carboxyfluorescein as the fluorescent pH probe, it was observed that Ca2+ entry into the vesicles is accompanied by an outward movement of H+ from the vesicles. Taken together, this paper establishes that the high-affinity transmembrane Ca2+-ATPase [Ghosh, Ray, Sarkar and Bhaduri (1990) J. Biol. Chem. 265, 11345-11351; Majumdar, Mukherjee, Ray and Bhaduri (1992) J. Biol. Chem. 267, 18440-18446] is an extrusion pump for Ca2+ in this human pathogen.

Adenosine Triphosphate↗
PubMed1997

Is patch testing necessary in vulval vestibulitis?

Allergic contact dermatitis has been suggested as a possible cause of vulval vestibulitis, a condition of unknown aetiology characterized by burning, stinging and dyspareunia, with symptoms localised to the vestibule. To examine this relationship, 30 women with vulval vestibulitis were patch tested using a standard series of contact allergens and a special series relevant to perianal and vulval disorders. Other potential allergens identified by the patients as causing aggravation were also included. There were 5 positive reactions, 4 to nickel and 1 to fragrance mix, though none of these reactions were considered relevant. Our results suggest that allergic contact dermatitis is unlikely to be a primary factor in the development or persistence of vulval vestibulitis. Patch testing patients with vulval vestibulitis cannot routinely be recommended.

Administration, Cutaneous↗
PubMed1997

Psychological and psychosexual aspects of vulvar vestibulitis.

AIMS: To objectively assess the psychological and psychosexual morbidity of patients with vulvar vestibulitis. METHODS: 30 patients with variable degrees of vulvar vestibulitis were recruited from a vulval clinic. Each patient underwent a detailed history and clinical examination. Friedrich's criteria were used for the diagnosis of vulvar vestibulitis. Standardised questionnaires to assess psychological and psychosexual function were completed by the patient before review. These questionnaires were the STAI and a modified psychosexual questionnaire introduced by Campion. RESULTS: Patients experienced considerable psychological dysfunction compared with controls. All aspects of psychosexual dysfunction were affected. CONCLUSIONS: When managing patients, psychosexual and psychological issues must be considered in addition to other conventional types of therapy. Vulvar vestibulitis may be a risk factor for developing psychosexual complications including vaginismus, low libido, and orgasmic dysfunction. Consideration of these factors must be an integral part of the management of patients with all chronic vulval conditions.

Adolescent↗
PubMed1997

Labial adhesion.

Explore the source record for details and available documents.

Herpes Labialis↗
PubMed1996

The chronically symptomatic vulva: prevalence in primary health care.

OBJECTIVES: To examine within the primary health care setting, the frequency of chronic vulval disorders, their frequency, investigation, management and referral patterns. METHODS: A questionnaire based survey at general practitioners surrounding a district general hospital. RESULTS: A total of 79 (72%) GPs replied to the questionnaire. Thirty-six (45%) GPs saw more than one patient per month with recurrent vulval symptoms and ten (13%) GPs saw more than three patients per month. The predominant symptom amongst patients with recurrent vulval symptoms was itching (55%) followed by soreness (26%), burning (14%) and dyspareunia (5%). Topical-antifungals and steroid medications were the commonest treatments prescribed for all women with vulval symptoms. CONCLUSIONS: Women who have vulval complaints commonly attend their GP for treatment. In many instances women with chronic vulval complaints are inadequately investigated and inappropriately managed.

Anti-Inflammatory Agents↗