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D Patel

Publications and source records attributed to D Patel.

At least 181 records · Page 10Linked to original sources
PubMed1990

Phenotypes and functions of lymphocytes in congenital toxoplasmosis.

Comparisons of lymphocyte surface phenotypes and functions were made among 25 pediatric patients with congenital toxoplasmosis (ages 1 month to 5 years) and 24 uninfected babies, a baby with postnatally acquired infection, and 6 uninfected, 7 recently infected, and 6 chronically infected adults. Percentages of lymphocytes with B1, T11, T3, T4, T8, T6, B4, Ia, NKH phenotypes and T4 to T8 ratios of infected and uninfected babies were the same (p greater than 0.05). Lymphocytes from congenitally infected babies had lower blastogenic responses (mean stimulation index [SI] = 5) to Toxoplasma lysate antigens (TLA) than lymphocytes from adult control groups with recent and chronic infection (Mean SIs = 32, 72; p less than 0.001). Compared to infected adults, congenitally infected children had similar or greater responses to concanavalin A (mean SIs = 94; 118, 76, p greater than 0.05) and in mixed leukocyte culture (mean SIs = 63; 22, 26, p greater than 0.05). For symptomatic babies, low blastogenic response to TLA correlated with more severe disease at presentation (p = 0.002). Lymphocyte blastogenic responses to TLA were increased for most children when they were older than 15 months, but responses remained less than adult levels for 9 of the 17 older children studied. There was no correlation between concomitant serum pyrimethamine levels and lymphocyte blastogenic responses to TLA. Pyrimethamine and sulfonamide treatment in vitro and in vivo did not alter lymphocyte response to TLA. Lymphocytes from congenitally infected babies failed to produce either gamma interferon or Interleukin 2 when cultured with TLA. In contrast, they produced these lymphokines when cultured with concanavalin A or phytohemagglutinin. Specific deficits in cell-mediated immune responses to TLA may account for the significant organ damage that occurs in infants and children with congenital toxoplasmosis.

Adult↗
PubMed1989

Purification of the E. coli ogt gene product to homogeneity and its rate of action on O6-methylguanine, O6-ethylguanine and O4-methylthymine in dodecadeoxyribonucleotides.

The E. coli gene ogt encodes the DNA repair protein O6-alkylguanine-DNA-alkyltransferase (O6-AlkG ATase). The protein coding region of the gene was cloned into a multicopy expression vector to obtain high yields of the enzyme (approximately 0.2% of total protein) which was purified to apparent homogeneity by affinity, molecular exclusion and reverse-phase chromatography. Good correlation was found between the determined and predicted amino acid compositions. The ability of the purified protein to act on O6-methylguanine (O6-MeG), O6-ethylguanine (O6-EtG) and O4-methylthymine (O4-MeT) in self-complementary dodecadeoxyribonucleotides was compared to that of 19 kDa fragment of the related ada-protein. With both proteins the rate order was O6-MeG greater than O6-EtG greater than O4-MeT, however, the ogt protein was found to repair O6-MeG, O6-EtG and O4-Met, 1.1, 173 and 84 times, respectively, faster than the ada protein.

Alkylating Agents↗
PubMed1989

NMR studies of DNA (R+)n.(Y-)n.(Y+)n triple helices in solution: imino and amino proton markers of T.A.T and C.G.C+ base-triple formation.

High-resolution exchangeable proton two-dimensional NMR spectra have been recorded on 11-mer DNA triple helices containing one oligopurine (R)n and two oligopyrimidine (Y)n strands at acidic pH and elevated temperatures. Our two-dimensional nuclear Overhauser effect studies have focused on an 11-mer triplex where the third oligopyrimidine strand is parallel to the oligopurine strand. The observed distance connectivities establish that the third oligopyrimidine strand resides in the major groove with the triplex stabilized through formation of T.A.T and C.G.C+ base triples. The T.A.T base triple can be monitored by imino protons of the thymidines involved in Watson-Crick (13.65-14.25 ppm) and Hoogsteen (12.9-13.55 ppm) pairing, as well as the amino protons of adenosine (7.4-7.7 ppm). The amino protons of the protonated (8.5-10.0 ppm) and unprotonated (6.5-8.3 ppm) cytidines in the C.G.C+ base triple provide distinct markers as do the imino protons of the guanosine (12.6-13.3 ppm) and the protonated cytidine (14.5-16.0 ppm). The upfield chemical shift of the adenosine H8 protons (7.1-7.3 ppm) establishes that the oligopurine strand adopts an A-helical base stacking conformation in the 11-mer triplex. These results demonstrate that oligonucleotide triple helices can be readily monitored by NMR at the individual base-triple level with distinct markers differentiating between Watson-Crick and Hoogsteen pairing. Excellent exchangeable proton spectra have also been recorded for (R+)n.(Y-)n.(Y+)n 7-mer triple helices with the shorter length permitting spectra to be recorded at ambient temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Composition↗
PubMed1989

NMR studies of exocyclic 1,N2-propanodeoxyguanosine adducts (X) opposite purines in DNA duplexes: protonated X(syn).A(anti) pairing (acidic pH) and X(syn).G(anti) pairing (neutral pH) at the lesion site.

Proton and phosphorus two-dimensional NMR studies are reported for the complementary d(C1-A2-T3-G4-X5-G6-T7-A8-C9).d(G10-T11-A12-C13-A14-C15-A 16-T17-G18) nonanucleotide duplex (designated X.A 9-mer) that contains a 1,N2-propanodeoxyguanosine exocyclic adduct, X5, opposite deoxyadenosine A14 in the center of the helix. The NMR studies detect a pH-dependent conformational transition; this paper focuses on the structure present at pH 5.8. The two-dimensional NOESY studies of the X.A 9-mer duplex in H2O and D2O solution establish that X5 adopts a syn orientation while A14 adopts an anti orientation about the glycosidic bond at the lesion site. The large downfield shift of the amino protons of A14 demonstrates protonation of the deoxyadenosine base at pH 5.8 such that the protonated X5(syn).A14(anti) pair is stabilized by two hydrogen bonds at low pH. At pH 5.8, the observed NOE between the H8 proton of X5 and the H2 proton of A14 in the X.A 9-mer duplex demonstrates unequivocally the formation of the protonated X5(syn).A14(anti) pair. The 1,N2-propano bridge of X5(syn) is located in the major groove. Selective NOEs from the exocyclic methylene protons of X5 to the major groove H8 proton of flanking G4 but not G6 of the G4-X5-G6 segment provide additional structural constraints on the local conformation at the lesion site. A perturbation in the phosphodiester backbone is detected at the C13-A14 phosphorus located at the lesion site by 31P NMR spectroscopy. The two-dimensional NMR studies have been extended to the related complementary X.G 9-mer duplex that contains a central X5.G14 lesion in a sequence that is otherwise identical with the X.A 9-mer duplex. The NMR experimental parameters are consistent with formation of a pH-independent X5(syn).G14(anti) pair stabilized by two hydrogen bonds with the 1,N2-propano exocyclic adduct of X5(syn) located in the major groove.

Base Composition↗
PubMed1989

Reactivities of polyclonal and monoclonal antibodies raised to the major capsid protein of human papillomavirus type 16.

Polyclonal and monoclonal antibodies have been raised against a fusion protein containing beta-galactosidase and part of the major capsid protein L1 of the human papillomavirus (HPV) type 16. The polyclonal antibodies cross-reacted with the L1 protein of several HPV types including HPV-1, -2, -6 and -11 when reacted with virus-infected tissue sections, and with HPV-6 and -18 L1 fusion proteins on Western blotting. Monoclonal antibodies against the L1 fusion protein of HPV-16 reacted only with HPV-16 L1 fusion proteins on Western blots and with HPV-16-containing biopsy sections as assessed by in situ DNA-DNA hybridization. These antibodies did not detect HPV-6 L1 protein after Western blotting or in HPV-6-infected tissue sections, although one did react with an HPV-18 fusion protein after Western blotting. The monoclonal antibodies were able to detect HPV-16 antigens in routine formaldehyde-fixed, wax-embedded sections of cervical intraepithelial neoplasia sections. HPV-16 L1 proteins were seen in one-third of biopsies that were positive using the polyclonal cross-reacting antisera. Polyclonal antibodies to fusion proteins containing part of the minor capsid protein L2 of HPV-6 or -16 appeared to be more type-specific as no cross-reactivity was seen when these antibodies were reacted with HPV-1- and -2-infected tissue sections.

Animals↗
PubMed1989

Identification of immunogenic regions of the major coat protein of human papillomavirus type 16 that contain type-restricted epitopes.

We have identified regions of the major capsid protein, L1, of the human papillomavirus (HPV) type 16 (HPV-16 L1), that are recognized by five monoclonal antibodies (MAbs) raised to a bacterial fusion protein containing residues 172 to 375 of HPV-16 L1. All five MAbs recognized HPV-16-infected tissue sections by immunohistochemistry, but not sections infected with HPV-1a (cutaneous warts), HPV-6b or -11 (genital warts). MAbs 3D1, 5A4 and 1D6 also recognized HPV-2-infected sections (cutaneous warts); MAb 8C4 recognized only sections containing HPV-16. Four MAbs (8C4, 3D1, 1D6 and 5A4) recognized a synthetic peptide corresponding to residues 269 to 284 of HPV-16 L1; within this region a minimum antibody binding site was identified, a tripeptide 276 to 278. However the complete epitope appears to extend beyond these residues and beyond HPV-16 L1 (269 to 284). The fifth MAb, 1C6, recognized bacterial fusion proteins containing HPV-6b L1, -16 L1 or -18 L1 using immunoblots, yet appeared HPV-16-specific when tested on infected tissue sections. This MAb recognized five amino acids within a different region of HPV-16 L1 (residues 299 to 313).

Amino Acid Sequence↗
PubMed1989

Immunophenotypic and enzymatic studies do not support the concept of mixed monocytic-granulocytic differentiation in acute promyelocytic leukaemia (M3): a study of 44 cases.

Leukaemic promyelocytes from 30 cases of hypergranular and 14 cases of hypogranular acute promyelocytic leukaemia (M3) were analysed for the presence of monocyte-associated characteristics to determine whether there was any evidence of mixed (hybrid) granulocytic-monocytic differentiation. Cytochemically, a high proportion of hypergranular cases showed significant alpha-naphthyl acetate esterase (ANAE) staining and simultaneous chloroacetate esterase, and ANAE expression by single cells was commonly seen. These atypical staining patterns were, however, not a feature of hypogranular cases. Immunophenotypic studies revealed that most hypergranular M3 cases were HLA-DR- and that monocyte-associated membrane CD14 expression was low in all cases tested. In addition, serum lysozyme concentrations (20 cases) were generally within the normal range and thus inconsistent with monocytic involvement in the leukaemic process. The significance of atypical ANAE staining of leukaemic promyelocytes was further examined by analysing ANAE isoenzyme components (defined by isoelectric focusing) in 11 cases. The patterns obtained (G1 and G2) were identical to those found in normal granulocytes and did not show any evidence of monocyte-associated esterase isoenzyme expression. On the basis of these findings, it is considered that the differentiation process in acute promyelocytic leukaemia is relatively well conserved and that the atypical esterase cytochemistry of hypergranular promyelocytes does not reflect their mixed lineage nature but is simply a consequence of increased granulation.

Cell Transformation, Neoplastic↗
PubMed1988

Intravenous radionuclide total body arteriography: a new technique.

We have developed a technique using a blood pool agent Tc-99m labeled red blood cells and a detector head set moving at a high speed to obtain total body arterial and blood pool images with only a single intravenous injection. Previously with an intravenous radiotracer injection, only regional arterial images could be obtained. Now, with this simple, non-invasive technique, we can evaluate the major arterial system, organs, and soft tissues in the whole body, as well as cardiac function. On reviewing 500 cases, more than 90% of the first-pass arterial phase images clearly demonstrated the aorta, ilio-femoral arteries, and, to a lesser extent, the more distal arteries in the lower extremities. The second-pass blood pool images revealed the anatomical and morphological status of the solid organs, as well as perfusion changes in various organs and soft tissues.

Adult↗
PubMed1988

IV radionuclide total-body arteriography: a new noninvasive whole-body screening procedure--a case report.

Recently the authors introduced a new technique of intravenous (IV) radionuclide total-body arteriography. The major arterial system, multiple organs of the whole body, and cardiac function can be evaluated with one small IV injection in the arm. After analyzing more than 1000 cases, they have found that many pathologies can be detected and/or confirmed in this procedure. This new technique may be used as a general whole-body screening test for those patients at high risk for disease.

Aged↗
PubMed1988

Clinical and angiographic comparison of asymptomatic occlusive cerebrovascular disease.

We compared clinical and arteriographic features in 106 patients with symptomatic unilateral carotid territory occlusive disease to determine the frequency and distribution of occlusive arterial lesions in asymptomatic vessels. Among black patients who were predominantly from Chicago, young, and female, there were fewer transient ischemic attacks and myocardial infarcts, less claudication, and more asymptomatic lesions of the supraclinoid internal carotid artery, anterior cerebral artery stem, and the middle cerebral artery stem. Among white patients predominantly from New England, elderly, and male, there was more frequent and severe occlusive asymptomatic disease at extracranial carotid and vertebral artery sites. Knowledge of the distribution of asymptomatic lesions will help guide evaluation and treatment strategies for patients with occlusive cerebrovascular disease.

Adult↗
PubMed1987

ICMR Task Force Study on hormonal contraception. Transfer of norethisterone (NET) and levonorgestrel (LNG) from a single tablet into the infant's circulation through the mother's milk.

A single tablet of either of the three different types of oral contraceptive preparations, viz. "Gynovlar" containing 3000 micrograms norethisterone (NET) and 50 micrograms ethinyl estradiol (EE2) or "Ovral" containing 250 micrograms levonorgestrel (LNG) and 50 micrograms EE2, or a daily progestogen only type--"Minipill" containing 30 micrograms of LNG only, were administered to 40 normal lactating women on a random basis. The sampling schedule in all the three body fluids, i.e. the maternal sera, breast milk and the infant's sera, was kept in such a manner that the peak levels of the contraceptive steroids would be expected to be present in these fluids. The results of this study indicate that the transfer ratio of LNG or NET from the maternal sera to her breast milk was approximately 10% (6-34%) for Gynovlar, 9% (5-18%) for Ovral and 6% (2-34%) for Minipill. However, it was interesting to observe that whereas the transfer ratio of NET or LNG from breast milk to infant's sera was similar for combination pills--8% (3-23%) for Gynovlar and 12% (3-42%) for Ovral, it was significantly higher for progestogen only Minipills--38% (13-92%) for LNG. The precise reason for the higher transfer ratio of LNG from breast milk to infant's serum in Minipill users cannot be explained.

Adult↗