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Biomedical subjects

S C Jain

Publications and source records attributed to S C Jain.

At least 109 records · Page 6Linked to original sources
PubMed1977

Mutagen-nucleic acid intercalative binding: structure of a 9-aminoacridine: 5-iodocytidylyl(3'-5')guanosine crystalline complex.

9-Aminoacridine forms a crystalline complex with the dinucleoside monophosphate, 5-iodocytidylyl(3'-5')guanosine. We have solved the three-dimensional structure of this complex by x-ray crystallography and have observed two distinct intercalative binding modes by this drug to miniature Watson-Crick double helical structures. The first of these involves a pseudosymmetric stacking interaction between 9-aminoacridine molecules and guanine-cytosine base-pairs. This configuration may be used by 9-aminoacridine when intercalating into DNA. The second configuration is an asymmetric interaction, largely governed by stacking forces between acridine and guanine rings. This type of association may play an important role in the mechanism of frameshift mutagenesis.

Acridines↗
PubMed1977

A survey of local public health departments and their directors.

In 1974 a questionnaire was mailed to the nation's local health officers. Responses were received from 1,345, at least 68 per cent of all local health departments. The present paper presents selected summary data from respondents concerning the health departments, their jurisdictions, organization, finance, functions, staffing, and about the training, salaries, and other characteristics of local health officers. Health departments are extensively involved in rendering health services, including direct personal services (25 per cent of all departments). For many services the health department is the sole provider of essential services in the area of jurisdiction. These services include ambulatory care (8 per cent), maternal and child health (48.5 per cent), home care (44.8 per cent), and family planning (38 per cent). The major constraints to improvement and expansion of programs are perceived as limited financial support, insufficient staff, and inadequate facilities.

Administrative Personnel↗
PubMed1977

Statutory authorizations for the work of local health departments.

A study of public health statutes of the 50 states identifies 44 specific services or functions that are assigned to local health departments by all or some of the states. Authorizations are most commonly assigned conjointly both to local and state health departments; exceptions are identified. Data suggest striking inconsistencies between what local health departments are authorized to perform and the services they actually render with regard to a selected group of programs that involve personal health services. The full scope of authorizations for local health departments is not revealed by examination of public health statutes. For this reason, among others, development of up-to-date health codes for all states would be beneficial.

Humans↗
PubMed1976

Organization of DNA in chromatin.

Conformational changes in DNA that accompany drug intercalation have led us to ask if DNA first bends or "kinks" to accept an intercalative drug or dye. Kinking is made possible by altering the normal C2' endo deoxyribose sugar ring puckering in B DNA to a mixed sugar puckering pattern of the type C3' and partially unstacking base-pairs. A kinking scheme such as this would require minimal stereochemical rearrangement and would also involve small energies. This has prompted us to ask more generally if a conformational change such as this could be used by proteins in their interactions with nucleic acids. In this papter we describe an interesting superhelical DNA structure formed by kinking DNA every 10 base-pairs. The structure may be used in the organization of DNA in chromatin.

Chemical Phenomena↗
PubMed1976

A modified chair geometry for whole body counting.

In the Marinelli chair, a geometry widely used in whole body counting, the lower part of the leg is seen quite inefficiently by the detector. The present paper describes an attempt to modify the standard chair geometry to minimise this limitation. The subject sits crossed-legged in the "Buddha Posture" in the standard chair. Studies with humanoid phantoms and a volunteer sitting in the Buddha posture show that this modification brings marked improvement over the Marinelli chair both from the point of view of sensitivity and uniformity of spatial response.

Humans↗
PubMed1975

Drug-nucleic acid interaction: X-ray crystallographic determination of an ethidium-dinucleoside monophosphate crystalline complex, ethidium: 5-iodouridylyl(3'-5')adenosine.

The intercalative trypanosomal drug, ethidium bromide, forms a crystalline complex with the dinucleoside monophosphate, 5-iodiuridylyl(3'-5')adenosine (iodoUpA). These crystals are monoclinic, space group C2, with unit cell dimensions, a = 2.845 nm, b = 1.354 nm, c = 3.413 nm, beta = 98.6 degrees. The structure has been solved to atomic resolution by Patterson and Fourier methods, and refined by full matrix least squares to a residual of 0.29 on 2017 observed reflexions. The asymmetric unit contains two ethidium molecules, two iodoUpA molecules, twenty water molecules and four methanol molecules, a total of 156 atims excluding hydrogens. The two iodoUpA molecules are held together by adenine-uracil Watson-Crick base-pairing. Adjacent base-pairs within this paired iodoUpA structure and between neighbouring iodoUpA molecules in adjoining unit cells are separated by 0.68 nm. This separation results from intercalative binding by one ethidium molecule and stacking by the other symmetry is utilized in this model drub-nucleic acid interaction, the intercalative ethidium molecule being oriented such that its phenyl and ethyl groups lie in the narrow groove of the miniature nucleic acid double helix. Solution studies have indicated a marked sequence specificity for ethidium-dinucleotide interactions and a probable structural explanation for this has been provided by this study.

Adenine Nucleotides↗
PubMed1975

X-ray crystallographic visualization of drug-nucleic acid intercalative binding: structure of an ethidium-dinucleoside monophosphate crystalline complex, Ethidium: 5-iodouridylyl (3'-5') adenosine.

We have cocrystallized the drug ethidium bromide with the dinucleoside monophosphate 5-iodouridylyl(3'-5')adenosine and have solved the three-dimensional structure to atomic resolution by x-ray crystallography. This has allowed the direct visualization of intercalative binding by this drug to a fragment of a nucleic acid double helix.

Adenine Nucleotides↗