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Biomedical subjects

N M Morris

Publications and source records attributed to N M Morris.

At least 37 records · Page 2Linked to original sources
PubMed1985

Calorimetric and potentiometric studies on the binding of calcium by phytic acid.

Potentiometric as well as thermal titrations of phytic acid and its calcium complexes have been conducted using both the batch and titration microcalorimeters. For phytic acid, the experimental values by either method are in excellent agreement. For the calcium complexes, the total number of groups and the total heat evolved are in agreement but the placement of the curves is different due primarily to the differences in calcium concentration. Binding of calcium by phytic acid is endothermic for the pH range 2.0-12.0 while the heat of dilution of 1 M CaCl2 is exothermic. The binding at pH greater than 11 gives a value of 22.5 +/- 0.9 kcal mol-1. The same enthalpy of binding (22.3 +/- 0.6 kcal mol-1) could be calculated for the entire pH range studied which requires a knowledge of the observed heat of binding, the thermal titration curves of the acid and its calcium complex, and the change in the hydrogen ion environment. Inspection of the thermal binding curves at pH greater than 11 indicates that a number of step-binding constants are involved and that 5.2 mol calcium are bound/mole phytic acid. This value has been confirmed by atomic absorption spectroscopy. Both the thermal and the potentiometric curves are reversible either by the instantaneous injection of acid or base or by continuous titration. Values for the ionization constants (as pK') and the enthalpy of ionization (as delta Hi) have been estimated by computer assisted curve fitting.

Calcium↗
PubMed1977

A study of the relationship between coitus and the luteinizing hormone surge.

Twenty-seven wives participating in a study of sexual activity patterns had identifiable shifts in basal body temperature and midcycle surges of serum luteinizing hormone (LH). When sexual activity data were examined using the LH surge as a centering point, it was observed that the day before the LH surge had only an average probability of coitus and organism. These findings suggest that neither coitus nor orgasm often triggers ovulation in humans. This cannot be taken as evidence that coitus-induced ovulation never occurs.

Adult↗
PubMed1977

The distribution of events in the human menstrual cycle.

Daily reports of 85 married couples concerning their sexual behaviour for about 3 menstrual cycles per couple were organized according to menstrual events by using six techniques of aggregation. While there were some similarities among the different displays, including an apparent peak about 6 days before mid-cycle, different methods of aggregation produce widely different frequency curves. It is concluded that there is no single method of display of events of the menstrual cycle which will fit all investigations.

Coitus↗
PubMed1976

The effect of subsidized family planning services on reproductive behavior in the United States, 1969-1974.

This paper evaluates the impact of federally subsidized family planning programs in the United States, from 1969 to 1974, on the reproductive behavior of ever-married women, 15-44 years old. The study began with an experimental design and the random assigment of areas to treatment and control but was completed as a multivariate analysis, treating program input as an interval-scaled independent variable. Using "before" and "after" area sample surveys and patient service data from operating programs, the demographic impact of the program was estimated. The impact detected was nonsignificant; according to our analysis, overall use of physician-administered contraception was not affected by the subsidized programs. The only program-induced change of activity related to reproduction that we recorded was increased use of subsidized services in study areas with high program input and increased use of private physician services where program input was low. These findings need to be interpreted with the caution usually exercised in evaluating imperfect field experiments.

Adolescent↗
PubMed1975

The frequency of sexual intercourse during pregnancy.

Reports of day-by-day sexual activity for the previous week were collected from a total community sample of over 900 pregnant and nonpregnant Thai women of childbearing age during a fertility survey in 1967-1968. About 13% of the women were pregnant. Examination of the women's intercourse frequencies at various stages of pregnancy revealed a downward trend as pregnancy progressed. However, a difference between the mean frequency for age-matched, nonmenstruating, nonpregnant women and that during any stage of pregnancy was not statistically significant at the p = 0.05 level (t test, two-tailed) until the seventh month. Much individual variation existed among the women. Complete abstinence from intercourse during the previous week reached a peak of 72.7% in the ninth month. The increase in abstinence with the progression of pregnancy appeared linear. The importance of these data lies in two methodological facts: they were collected from a total population sample and are therefore unbiased by sample selection; the women were not asked to report their "average" frequencies for some time period in the past. Reports of behavior on each day of only the preceding week were the basis for the conclusion. Although the women are from a different culture, lay and professional advice concerning intercourse during pregnancy is similar to that in the United States. Because intercourse may be discouraged, particularly in the third trimester, it is difficult to attribute the observation of the gradual decline in frequency to a "physiological" reason. This tempting hypothesis, however, is worthy of further study.

Adolescent↗