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S C Jain

Publications and source records attributed to S C Jain.

At least 73 records · Page 4Linked to original sources
PubMed1984

Visualization of drug-nucleic acid interactions at atomic resolution. VII. Structure of an ethidium/dinucleoside monophosphate crystalline complex, ethidium: uridylyl(3'-5') adenosine.

Ethidium forms a crystalline complex with the dinucleoside monophosphate, uridylyl (3'-5') adenosine (UpA). The complex crystallizes in the monoclinic space group P2l with unit cell dimensions, a = 13.704 A, b = 31.674 A, c = 15.131 A, beta = 113.9 degrees. This light atom structure has been solved to atomic resolution and refined by full matrix least squares to a residual of 0.12, using 3,034 observed reflections. The asymmetric unit consists of two ethidium molecules, two UpA molecules and 19 solvent molecules, a total of 145 non-hydrogen atoms. The two UpA molecules are hydrogen-bonded together by Watson-Crick type base pairing. Base-pairs in this duplex are separated by 6.7 A; this reflects intercalative binding by one of the ethidium molecules. The other ethidium molecule stacks on either side of the intercalated base-paired dinucleoside monophosphate, being related by a unit cell translation along the a axis. The conformation of the sugar-phosphate backbone accompanying intercalation has been accurately determined in this analysis, and contains the mixed sugar-puckering pattern: C3' endo (3'-5') C2' endo. This same structural feature has been observed in the ethidium-iodoUpA and ethidium-iodoCpG complexes, and exists in two additional structures containing ethidium-CpG. Taken together, these studies confirm our earlier sugar-puckering assignments and demonstrate that iodine covalently bound to the C5 position on uridine or cytosine does not alter the basic sugar-phosphate geometry or the mode of ethidium intercalation in these model studies. We have proposed this stereochemistry to explain the intercalation of ethidium (as well as other simple intercalators) into both DNA and into double-helical RNA, and discuss this aspect of our work further in this paper and in the accompanying papers.

Binding Sites↗
PubMed1984

Visualization of drug-nucleic acid interactions at atomic resolution. VIII. Structures of two ethidium/dinucleoside monophosphate crystalline complexes containing ethidium: cytidylyl(3'-5') guanosine.

This paper describes two complexes containing ethidium and the dinucleoside monophosphate, cytidylyl(3'-5')guanosine (CpG). Both crystals are monoclinic, space group P2l, with unit cell dimensions as follows: modification 1: a = 13.64 A, b = 32.16 A, c = 14.93 A, beta = 114.8 degrees and modification 2: a = 13.79 A, b = 31.94 A, c = 15.66 A, beta = 117.5 degrees. Each structure has been solved to atomic resolution and refined by Fourier and least squares methods; the first has been refined to a residual of 0.187 on 1,903 reflections, while the second has been refined to a residual of 0.187 on 1,001 reflections. The asymmetric unit in both structures contains two ethidium molecules and two CpG molecules; the first structure has 30 water molecules (a total of 158 non-hydrogen atoms), while the second structure has 19 water molecules (a total of 147 non-hydrogen atoms). Both structures demonstrate intercalation of ethidium between base-paired CpG dimers. In addition, ethidium molecules stack on either side of the intercalated duplex, being related by a unit cell translation along the a axis. The basic feature of the sugar-phosphate chains accompanying ethidium intercalation in both structures is: C3' endo (3'-5') C2' endo. This mixed sugar-puckering pattern has been observed in all previous studies of ethidium intercalation and is a feature common to other drug-nucleic acid structural studies carried out in our laboratory. We discuss this further in this paper and in the accompanying papers.

Binding Sites↗
PubMed1983

Termination of pregnancy in teenagers.

This is a study of some epidemiological aspects of fifty-three unmarried girls, aged sixteen years and under, who were referred for therapeutic termination of pregnancy during the year 1976. Although the results showed that the overall abortion rate in Canada is much higher than in Newfoundland, the abortion rate in the 14-16 year age group is higher in the Province than in the rest of Canada. Secondly, the abortion rate for the fifteen year age group in this Province is higher than that for the sixteen year old girls, suggesting that more pregnancies in the older age group go to term. The rate of abortions among some religious denominations is significantly higher than in others. Urban living does not appear to produce an increase in abortion rates in these age groups. Interruption of schooling due to the occurrence of pregnancy is not a cause for concern in about half of this group. There is some evidence in support of the contention that precocious maturation is related to early pregnancy.

Abortion, Therapeutic↗
PubMed1981

Body composition of high altitude natives on descent to the plains: a densitometric, hydrometric, and anthropometric evaluation.

Body density was experimentally determined at a field location at 3,920 m on 32 medically fit and active high altitude native males using a water displacement technique. Stature, body weight and the bony widths at the elbow, wrist, knee, and ankles; and thickness of skin folds at eight sites were measured. Based on body density and bony widths, body fat, total body water (TBW), mineral mass and total cell solids (TCS) were calculated. Similar measurements were made on another group of 16 high altitude natives after one months stay in Dehli (200 m). TBW of 11 of these subjects was experimentally determined by the oral administration of 200 muCi of tritiated water. This group of subjects was physically less active in Delhi. At high altitude the natives consumed a balanced diet which provided 20.21 MJ, but in the plains the diet provided only 15.69 MJ though it was nutritionally balanced. In spite of the reduced calorie intake this group showed greater fat content in Delhi than the group located at high altitude. These men were also hyperhydrated. Hyperhydration of the lean body could be an adaptive response of the high altitude natives to the new environment. Due to the disturbed state of hydration of the lean body of these men in the plains, use of Siri's formula for the computation of total body fat is questioned.

Adaptation, Physiological↗
PubMed1981

The program implications of administrative relationships between local health departments and state and local government.

A typology of organizational arrangements between state and local public health agencies was used as a framework within which the organizational environment of the local health department was studied for its effects on program development and implementation by local public health departments. Data collected in a national sample of local health officers were used in measuring the effect of four different patterns of administrative relationships on the selected characteristics of local health department programs. Important differences were observed among the four organizational types with regard to constraints on programs and program priorities, and health officers' perceptions of the primary functions of local health departments and sources of local health department funding. These findings were then used as a baseline from which to consider the possible impact of recent federal health budgetary proposals (specifically, block grants) both on existing patterns of intergovernmental relations and on the funding and operation of local health department programs. It was determined that the most likely general development arising from these proposed changes in federal budgetary policy is that the administrative control of state health agencies over those at the local level is likely to be enhanced. Other likely developments include changes in the programs and priorities of local health departments related to reductions in overall funding levels for human services and forced competition for fewer dollars by an enlarged constituency.

Community Health Services↗
PubMed1980

Truncus arteriosus communis, an unusual anatomical variant of type I.

We present a case of type I truncus arteriosus communis characterized by the horizontal origin of the main pulmonary artery from the common trunk and by a winding course up to a total length of 11.5 cm to the point of bifurcation of the pulmonary artery. Other than cyanosis the patient had a normal clinical history, which was followed for 20 years. The length of the main pulmonary artery could be related to the lower site of the incomplete septation of the common trunk, and it seems that hemodynamic factors contributed to this unusual configuration.

Angiocardiography↗