Biomedical subjects

A V Sarma

Publications and source records attributed to A V Sarma.

13 recordsLinked to original sources

PubMed2006

Polymorphisms in the prostate-specific antigen gene promoter do not predict serum prostate-specific antigen levels in African-American men.

A major problem with the use of serum prostate-specific antigen (PSA) in predicting prostate cancer risk is the considerable variability of such measurements. Cramer et al. identified a set of single-nucleotide polymorphisms (SNPs) in the upstream regulatory region of the PSA gene that were each associated with increased promoter activity and serum PSA, further suggesting that genotyping these SNPs could be useful in improving the predictive value of PSA screening. In order to replicate this finding, DNA samples from 475 African-American men were genotyped for the same SNPs and no association was observed with either serum PSA level or prostate cancer diagnosis.

Adult↗

PubMed2001

Preferential incorporation of glucosamine into the galactosamine moieties of chondroitin sulfates in articular cartilage explants.

OBJECTIVE: To determine the metabolic fate of glucosamine (GlcN) in intact articular cartilage tissue. METHODS: Intact articular cartilage explants were cultured for up to 13 days in Dulbecco's modified Eagle's medium supplemented with 1) 1-13C-labeled GlcN, 2) 1-13C-labeled glucose (Glc), or 3) no labeling. Every 3-4 days, samples were removed and frozen in liquid nitrogen for carbon-13 magnetic resonance spectroscopic (MRS) analysis. The metabolic products of the labeled precursors were determined from the MRS data based on resonance positions and comparison with known standards and published values. RESULTS: GlcN was taken up by the chondrocytes and incorporated selectively into the hexosamine, but not the hexuronic acid, components of the glycosaminoglycan chains of articular cartilage proteoglycan. The data also demonstrated that GlcN is the substrate of choice for the galactosamine moieties of the chondroitin sulfates, incorporating at levels 300% higher than with an equivalent amount of labeled Glc. CONCLUSION: The results indicate that GlcN facilitates the production of proteoglycan components that are synthesized through the hexosamine biochemical pathway.

Animals↗

PubMed2001

Phospholipid composition of articular cartilage boundary lubricant.

The mechanism of lubrication in normal human joints depends on loading and velocity conditions. Boundary lubrication, a mechanism in which layers of molecules separate opposing surfaces, occurs under severe loading. This study was aimed at characterizing the phospholipid composition of the adsorbed molecular layer on the surface of normal cartilage that performs as a boundary lubricant. The different types of phospholipid adsorbed onto the surface of cartilage were isolated by extraction and identified by chromatography on silica gel paper and mass spectroscopy. The main phospholipid classes identified were quantified by a phosphate assay. Gas chromatography and electrospray ionization mass spectrometry were used to further characterize the fatty acyl chains in each major phospholipid component and to identify the molecular species present. Phosphatidylcholine (41%), phosphatidylethanolamine (27%) and sphingomyelin (32%) were the major components of the lipid layer on the normal cartilage surface. For each lipid type, a mixture of fatty acids was detected, with a higher percentage of unsaturated species compared to saturated species. The most abundant fatty acid observed with all three lipid types was oleic acid (C18:1). Additional work to further quantify the molecular species using electrospray ionization mass spectrometry is recommended.

Animals↗

PubMed2001

A prospective study of EUS-guided celiac plexus neurolysis for pancreatic cancer pain.

BACKGROUND: Celiac plexus neurolysis, a chemical splanchnicectomy of the celiac plexus, is used to treat pain caused by pancreatic cancer. Most commonly, celiac plexus neurolysis is performed percutaneously under CT or fluoroscopic guidance, but can also be performed with EUS. The aim of this study was to prospectively assess the efficacy of EUS celiac plexus neurolysis in the management of pain caused by pancreatic cancer. METHODS: In this prospective study conducted in a community-based referral hospital, 58 patients with painful and inoperable pancreatic cancer were evaluated at 8 observation points before and after EUS celiac plexus neurolysis for up to 6 months. The following data were collected: age, gender, tumor location, vascular invasion, adjuvant therapy, and laboratory tests including prothrombin time, and complete blood counts were obtained at baseline (before EUS celiac plexus neurolysis); pain scores, morphine use, and adjuvant therapy were assessed at each observation. RESULTS: Pain scores were lower (p = 0.0001) 2 weeks after EUS celiac plexus neurolysis, an effect that was sustained for 24 weeks when adjusted for morphine use and adjuvant therapy. Forty-five of the 58 patients (78%) experienced a decline in pain scores after EUS celiac plexus neurolysis. Chemotherapy with and without radiation also decreased pain after EUS celiac plexus neurolysis (p = 0.002). Procedure-related transient abdominal pain was noted in 5 patients; there were no major complications. CONCLUSIONS: EUS celiac plexus neurolysis is safe and controls pain caused by unresectable pancreatic cancer.

Aged↗

PubMed2000

Norbornene-constrained cyclic peptides with hairpin architecture: design, synthesis, conformation, and membrane ion transport.

A novel family of hairpin cyclic peptides has been designed on the basis of the use of norbornene units as the bridging ligands. The design is flexible with respect to the choice of an amino acid, the ring size, and the nature of the second bridging ligand as illustrated here with the preparation of a large number of norborneno cyclic peptides containing a variety of amino acids in ring sizes varying from 12- to 29-membered, with the choice of the second bridging ligand being a rigid norbornene (11, 13a,b), an adamantane unit (7a,b and 8), or a flexible cystine residue (4a,b and 10). The presence of built-in handles (as protected COOH groups) permits the attachment of a variety of subunits as shown here with the ligation of Leu-Leu, Val-Val, or Aib-Aib pendants in 4b, 7b, and 13b, respectively. This novel class of constrained cyclic peptides are demonstrated to adopt beta-sheet- or hairpin-like conformation as shown by (1)H NMR and CD spectra. Membrane ion-transport studies have shown that the norborneno cyclic peptides 4b and 7b containing Leu-Leu or Val-Val pendants symmetrically placed on the exterior of the ring show high efficiency and selectivity in the transport of specifically monovalent cations. This property can be attributed to the hairpin-like architecture induced by the norbornene unit since the bis-adamantano peptide 15 containing two pairs of Leu-Leu pendants on the exterior is able to transport both monovalent (Na(+), K(+)) and divalent (Mg(2+)/Ca(2+)) cations.

Circular Dichroism↗

PubMed2000

Channel-forming, self-assembling, bishelical amphiphilic peptides: design, synthesis and crystal structure of Py(Aibn)2, n=2,3,4.

The design, synthesis, characterization and self-assembling properties of a new class of amphiphilic peptides, constructed from a bifunctional polar core attached to totally hydrophobic arms, are presented. The first series of this class, represented by the general structure Py(Aibn)2 (Py=2,6-pyridine dicarbonyl unit; Aib=alpha, alpha'-dimethyl glycine; n=1-4), is prepared in a single step by the condensation of commercially available 2,6-pyridine dicarbonyl dichloride with the methyl ester of homo oligoAib peptide (Aibn-OMe) in the presence of triethyl amine. 1H NMR VT and ROESY studies indicated the presence of a common structural feature of 2-fold symmetry and an NH...N hydrogen bond for all the members. Whereas the Aib3 segment in Py(Aib3)2 showed only the onset of a 3(10)-helical structure, the presence of a well-formed 3(10)-helix in both Aib4 arms of Py(Aib4)2 was evident in the 1H NMR of the bispeptide. X-ray crystallographic studies have shown that in the solid state, whereas Py(Aib2)2 molecules organize into a sheet-like structure and Py(Aib3)2 molecules form a double-stranded string assembly, the tetra Aib bispeptide, Py(Aib4)2, is organized to form a tetrameric assembly which in turn extends into a continuous channel-like structure. The channel is totally hydrophobic in the interior and can selectively encapsulate lipophilic ester (CH3COOR, R=C2H5, C5H11) molecules, as shown by the crystal structures of the encapsulating channel. The crystal structure parameters are: 1b, Py(Aib2)2, C25H37N5O8, sp. gr. P2(1)2(1)2(1), a=9.170(1) A, b=16.215(2) A, c=20.091(3) A, R=4.80; 1c, Py(Aib3)2, C33H51N7O10H2O, sp. gr. P1, a=11.040(1) A, b=12.367(1) A, c=16.959(1) A, alpha =102.41 degrees, beta =97.29 degrees, gamma =110.83 degrees, R1=6.94; 1 da, Py(Aib4)2.et ac, C41H65N9O12.1.5H2O.C4H8O2, sp. gr. P1, a=16.064(4) A, b=16.156 A, c=21.655(5) A, alpha =90.14(1)degrees, beta=101.38(2) degrees, gamma=97.07(1)degrees, Z=4, R1=9.03; 1db, Py(Aib4)2.amylac, C41H65N9O12.H2O.C7H14O2, P2(1)/c, a=16.890(1) A, b=17.523(1)A, c=20.411(1) A, beta=98.18 degrees, Z=4, R=11.1 (with disorder).

Acetates↗

PubMed1999

Epidemiology of vulvar vestibulitis syndrome: an exploratory case-control study.

BACKGROUND: Vulvar vestibulitis syndrome (VVS) is a chronic, persistent syndrome characterised by vestibular pain, tenderness, and erythema. The aetiology of VVS is unknown and few of the hypothesised risk factors have been tested in controlled studies. METHODS: Using a matched case-control study design, medical, sexual, health behaviour, and diet history of 28 women with VVS were compared with 50 friend controls without VVS to identify possible causal factors. RESULTS: Cases were more likely than controls to report every vaginal and urinary symptom at the time of interview measured, particularly vaginal soreness or pain (60.7%) and pain during intercourse (64.3%). There were no significant differences between cases and controls with respect to sexual behaviour. Cases were more likely than controls to report self reported history of physician diagnosed bacterial vaginosis (OR = 22.2, 95% CI = 2.8, 177.2, p value = 0.0001), vaginal yeast infections (OR = 4.9, 95% CI = 1.4, 18.0, p value = 0.01), and human papillomavirus (OR = 7.1, 95% CI = 0.6, 81.2, p value = 0.08). There were no differences between cases and controls with respect to dietary intake of oxalate. Cases were more likely than controls to report poor health status (OR = 5.7, 95% CI = 1.1, 28.7, p value = 0.02) and history of depression for 2 weeks or more during the past year (OR = 4.4, 95% CI = 1.6, 12.3, p value = 0.002). CONCLUSION: Self reported history of bacterial vaginosis, yeast infections, and human papillomavirus were strongly associated with VVS. An infectious origin for VVS should be pursued in larger controlled studies, using questionnaire and laboratory measures.

Adolescent↗

PubMed1997

NMR study of the peptide present in the principal neutralizing determinant (PND) of HIV-1 envelope glycoprotein gp120.

The peptide sequence Gly-Pro-Gly-Arg-Ala-Phe (GPGRAF) is present in many principal neutralizing determinants (PND) of the human immunodeficiency virus type-1 (HIV-1). It has been shown that peptides from the PND sequence contain a significant beta turn in the conserved Gly-Pro-Gly-Arg sequence. In order to find out whether or not the smaller subunits also contain this turn, we have studied the NMR of a hexapeptide [GPGPRAF, peptide (I)], a heptapeptide Gly-Pro-Gly-Arg-Ala-Phe-Cys [GPGRAFC, peptide (II)] and a dodecapeptide [GPGRAFGPGRAF, peptide (III)], retaining the side chain protecting groups. Although the majority of conformations for these peptides are disordered, there is a considerable propensity of structures with beta turn in the GPGR sequence. While peptide (I) and peptide (III) seem to have both type I and type II beta turn conformations, peptide (II) shows a propensity of only type II beta turn. The nascent structures obtained in these peptides may get stabilized as the receptor binding conformation in the presence of the receptors, thus playing a significant role in vaccine development against HIV.

HIV Envelope Protein gp120↗

PubMed1996