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A Soni

Publications and source records attributed to A Soni.

9 recordsLinked to original sources
PubMed1989

Fidelity of two retroviral reverse transcriptases during DNA-dependent DNA synthesis in vitro.

We determined the fidelity of avian myeloblastosis virus and Moloney murine leukemia virus reverse transcriptases (RTs) during DNA synthesis in vitro using the M13mp2 lacZ alpha gene as a mutational target. Both RTs commit an error approximately once for every 30,000 nucleotides polymerized. DNA sequence analysis of mutants generated in a forward mutation assay capable of detecting many types of errors demonstrated that avian myeloblastosis virus RT produced a variety of different mutations. The majority (58%) were single-base substitutions; all of which resulted from the misincorporation of either dAMP or dGMP. Minus-one frameshifts were also common, composing about 30% of the mutations. In addition to single-base events, eight mutants contained sequence changes involving from 2 to 59 bases. The frequency of these mutants suggests that, at least during DNA synthesis in vitro, RTs also commit errors by mechanisms other than classical base miscoding and misalignment. We examined the ability of RTs to synthesize DNA from a mismatched primer terminus at a sequence where the mismatched base was complementary to the next base in the template. Unlike cellular DNA polymerases which polymerize from the mismatched template-primer, RTs preferred to polymerize from a rearranged template-primer containing a matched terminal base pair and an unpaired base in the template strand. The unusual preference for this substrate suggests that the interactions between RTs and the template-primer are different from those of cellular DNA polymerases. The overall error rate of RT in vitro is sufficient to account for the estimated mutation rate of these viruses.

Avian Myeloblastosis Virus↗
PubMed1989

Hyponatremia in patients with the acquired immunodeficiency syndrome.

Of 103 patients with the acquired immunodeficiency syndrome (AIDS) admitted for acute opportunistic infections, 36 had serum sodium less than or equal to 130 mEq/l (130 mmol/l). In 12 the hyponatremia was associated with volume depletion and corrected with saline replacement therapy. In 23 it was associated with the syndrome of inappropriate antidiuretic hormones secretion (SIADH). One patient had adrenal insufficiency and the serum sodium corrected after steroid replacement. We conclude that hyponatremia is a common electrolyte abnormality in AIDS patients suffering acutely from opportunistic infections and that SIADH and volume depletion are important contributing factors.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Evidence for an HIV-related nephropathy: a clinico-pathological study.

The existence of an HIV-related nephropathy as a distinct disease entity is controversial. We observed a high incidence of renal disease in our AIDS patients. Of 182 patients, 59 patients (32.4%) were found to have heavy proteinuria (greater than 2 g/24 h). Of these, 24 patients had slow progression of renal insufficiency and 2 patients had rapid deterioration to end stage renal disease. There was a notable absence of hypertension in these cases. The incidence of proteinuria was similar in blacks and hispanics; however 22.8% of blacks had renal insufficiency as compared to 6.9% of hispanics. There was no difference in the incidence of heavy proteinuria between intravenous drug abusers (32.3%) and nonabusers (33.3%). Renal morphology when examined showed characteristic changes, including cytomembranous structures and virus-like particles. These changes were similar in patients with heavy or light proteinuria, though they were less severe in the latter. We conclude that a HIV-related nephropathy exist and the presence of cytomembranous structures and virus-like particles in the renal tissue raises the possibility of a viral etiology for this disorder.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Tubuloreticular inclusions in colonic mucosa as diagnostic markers of AIDS.

Tubuloreticular inclusions (TRI) are known to be associated with viral infections and are considered highly specific of the acquired immune deficiency syndrome (AIDS) in the appropriate clinical setting. We describe a homosexual man without any evidence of AIDS who presented with diarrhea. A search for the usual pathogens was unsuccessful, but electronmicroscopic examination of colonic mucosa revealed numerous tubuloreticular inclusions. The diarrhea subsided and 2 months later the patient developed Pneumocystis carinni pneumonia. This observation suggests that the detection of TRI in the colonic mucosa can precede the clinical manifestations of AIDS, and these structures can be useful markers for the future development of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Exonucleolytic proofreading enhances the fidelity of DNA synthesis by chick embryo DNA polymerase-gamma.

The high fidelity of chick embryo DNA polymerase-gamma (pol-gamma) observed during in vitro DNA synthesis (Kunkel, T. A. (1985) J. Biol. Chem. 260, 12866-12874) has led us to examine this DNA polymerase for the presence of an exonuclease activity capable of proofreading errors. Highly purified chick embryo pol-gamma preparations do contain exonuclease activity capable of digesting radiolabeled DNA in a 3'----5' direction, releasing deoxynucleoside 5'-monophosphates. The polymerase and exonuclease activities cosediment during centrifugation in a glycerol gradient containing 0.5 M KCl. In the absence of dNTP substrates, this exonuclease excises both matched and mismatched primer termini, with a preference for mismatched bases. Excision is inhibited by the addition of nucleoside 5'-monophosphates to the digestion reaction. In the presence of dNTP substrates to permit competition between excision and polymerization from the mismatched primer, the exonuclease excises mismatched bases from preformed terminal mispairs with greater than 98% efficiency. The preference for excision over polymerization can be diminished by addition of either high concentrations of dNTP substrates or nucleoside 5'-monophosphates to the exonuclease/polymerase reaction. To determine if this exonuclease is capable of proofreading misinsertions produced during a normal polymerization reaction, a sensitive base substitution fidelity assay was developed based on reversion of an M13mp2 lacZ alpha nonsense codon. In this assay using reaction conditions that permit highly active exonucleolytic proofreading, pol-gamma exhibits a fidelity of less than one error for every 260,000 bases polymerized. As for terminal mismatch excision, fidelity is reduced by the addition to the synthesis reaction of high concentrations of dNTP substrates or nucleoside 5'-monophosphates, both hallmarks of exonucleolytic proofreading by prokaryotic enzymes. Taken together, these observations suggest that the 3'----5' exonuclease present in highly purified chick embryo pol-gamma preparations proofreads base substitution errors during DNA synthesis. It remains to be determined if the polymerase and exonuclease activities reside in the same or different polypeptides.

Animals↗
PubMed1988

Renal cytomembranous inclusions in idiopathic renal disease as predictive markers for the acquired immunodeficiency syndrome.

Tubuloreticular inclusions (TRI) and cylindrical confronting cisternae (CCC) are present in cells of patients with the acquired immunodeficiency syndrome (AIDS) and have also been detected in the kidneys of individuals with AIDS and heavy proteinuria. We examined renal biopsy tissue from 13 patients with proteinuria and/or renal insufficiency. At the time of biopsy, two of the patients had AIDS (group A), four had AIDS-related complex (ARC) (group B), and seven presented without any clinical signs or symptoms characteristic of AIDS or ARC. These seven had risk factors for AIDS, and systemic lupus erythematosus (SLE) was excluded in all. Abundant TRI were present in the renal endothelial and fibroblastic interstitial cells in all patients from group A and B and in four patients who had no evidence for AIDS or ARC at the time of biopsy (group C). These individuals were followed, and all developed AIDS within a period of 3 to 14 months. CCC were detected in two of two patients in group A, one of four in group B, and one of four in group C. TRI and CCC were not present in the renal tissue of the remaining three patients; they did not develop ARC or AIDS over a prolonged observation period. Our findings suggest that TRI and TRF are ultrastructural markers for human immunodeficiency virus (HIV) associated nephropathy and can be seen before AIDS has manifested itself. These structures may be of predictive value for the future development of AIDS in patients presenting with apparent idiopathic renal disease.

AIDS-Related Complex↗
PubMed1979

Stabilized record bases for complete dentures.

A step-by-step technique has been described to construct stabilized record bases which allows the dentist to take advantage of undercuts through the use of a resilient denture liner material in the undercut regions. The resilient denture liner material protects the rugae and prevents damage to the casts in the undercut regions during repeated placing and removal from the cast. Shellac denture base material at the posterior limit of the record base permits an easy method of checking the posterior palatal seal. The incorporation of the posterior palatal seal in the record base allows for adequate retention during the recording of the maxillomandibular jaw relation records and try-in procedures. The record bases made by the sprinkle-on technique are preferred to those made using the dough method. The bases are rigid, stable, not easily broken or warped, and fit accurately.

Dental Occlusion↗