Biomedical subjects

G Sundaram

Publications and source records attributed to G Sundaram.

6 recordsLinked to original sources

PubMed2004

Bonding to and protecting worn palatal surfaces of teeth with dentine bonding agents.

Dentine bonding resins may play a role in protecting dentine against acids for patients with erosion. Therefore, it is important to try and understand what potential difficulties may ensue when bonding to worn dentine. This paper reviews the literature on the changes between normal and worn dentine and the effect of this on the bonding to composite resins. A medline search was undertaken using the terms erosion, tooth wear and dentine bonding up until the spring of 2003. Although there are changes on the surface of worn dentine, there is little evidence that this may affect the bond.

Acrylic Resins↗

PubMed2001

Preventative measures for bulimic patients with dental erosion.

The preventative techniques suggested to bulimic patients are frequently undervalued and ignored in favour of restorative treatment, possibly because the dentist may not be aware of the eating disorder. Educating bulimic patients about fluoride application, the use of brushing techniques, antacids, cheese, xylitol chewing gum and the possible use of mouth guards may minimise the effect of acids. Together with attempts at improving patient compliance they can be a valuable adjunct to treatment of bulimic patients with dental problems. Monitoring the wear on teeth by comparing study casts is a good way to maintain control but there are circumstances when restorations are indicated, perhaps when further delay may result in the prognosis of the teeth being compromised. Following a brief introduction to causes of bulimia and the consequences to the dentition, this paper, based on a literature review, considers patient-orientated techniques for prevention and provisional management of erosion of dental hard tissues for patients with bulimia nervosa.

Antacids↗

PubMed1995

Reconstructing strings from substrings.

We consider an interactive approach to DNA sequencing by hybridization, where we are permitted to ask questions of the form "is s a substring of the unknown sequence S?", where s is a specific query string. We are not told where s occurs in S, nor how many times it occurs, just whether or not s a substring of S. Our goal is to determine the exact contents of S using as few queries as possible. Through interaction, far fewer queries are necessary than using conventional fixed sequencing by hybridization (SBH) sequencing chips. We provide tight bounds on the complexity of reconstructing unknown strings from substring queries. Our lower bound, which holds even for a stronger model that returns the number of occurrence of s as a substring of S, relies on interesting arguments based on de Bruijn sequences. We also demonstrate that subsequence queries are significantly more powerful than substring queries, matching the information theoretic lower bound. Finally, in certain applications, something may already be known about the unknown string, and hence it can be determined faster than an arbitrary string. We show that building an optimal decision tree is NP-complete, then give an approximation algorithm that gives trees within a constant multiplicative factor of optimal.

Algorithms↗

PubMed1994

A partial digest approach to restriction site mapping.

We present a new, practical algorithm to resolve the experimental data in restriction site analysis, which is a common technique for mapping DNA. Specifically, we assert that multiple digestions with a single restriction enzyme can provide sufficient information to identify the positions of the restriction sites with high probability. The motivation for the new approach comes from combinatorial results on the number of mutually homeometric sets in one dimension, where two sets of n points are homeometric if the multiset of n(n-1)/2 distances they determine are the same. Since experimental data contain errors, we propose algorithms for reconstructing sets from noisy interpoint distances, including the possibility of missing fragments. We analyse the performance of these algorithms under a reasonable probability distribution, establishing a relative error limit of r = theta(1/n2) beyond which our technique becomes infeasible. Through simulations, we establish that our technique is robust enough to reconstruct data with relative errors of up to 7.0% in the measured fragment lengths for typical problems, which appears sufficient for certain biological applications.

Algorithms↗

PubMed1993

A partial digest approach to restriction site mapping.

We present a new practical algorithm to resolve the experimental data of restriction site analysis, which is a common technique for mapping DNA. Specifically, we assert that multiple digests with a single restriction enzyme can provide sufficient information to identify the positions of the restriction sites with high probability. The motivation for the new approach comes from combinatorial results on the number of mutually homeometric sets in one dimension, where two sets of n points are homeometric if the multiset of (n2) distances they determine are the same. Since experimental data contains error, we propose algorithms for reconstructing sets from noisy interpoint distances, including the possibility of missing fragments. We analyze the performance of these algorithms under a reasonable probability distribution, establishing a relative error limit of r = theta (1/n2) beyond which our technique becomes infeasible. Through simulations, we establish that our technique is robust enough to reconstruct data with relative errors of up to 7.0% in the measured fragment lengths for typical problems, which appears sufficient for certain biological applications.

Algorithms↗

PubMed1984

The effect of alpha-tocopherol on premenstrual symptomatology: a double-blind study. II. Endocrine correlates.

In a randomized, double-blind, dose-response study, alpha-tocopherol significantly ameliorated symptoms in three of the four classes of the premenstrual syndrome (PMS). Alpha-tocopherol treatment had no significant effect on serum concentrations of testosterone, dehydroepiandrosterone sulfate (DHEA-S), estradiol, and progesterone. However, independent of treatment, a significant correlation emerged between temporal changes in one PMS category and changes in DHEA-S concentrations. These results suggest that improvement in PMS severity is not mediated through direct effects of alpha-tocopherol on serum steroids. Androgens, however, may play a role in some PMS symptomatology.

Clinical Trials as Topic↗