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The mechanism and hormonal regulation of lactation is explained and illustrated with a schematic representation. Circulating estrogen above a critical amount seems to be the inhibitory factor controlling lactation during pregnancy. Once delivery occurs, the level of estrogen falls, that of prolactin rises, and lactation begins. Nonsuckling can be used to inhibit lactation. Estrogens can also be used to inhibit lactation more quickly and with less pain. The reported association between estrogens and puerperal thromboembolism cannot be considered conclusive due to defects in the reporting studies. There is no reason not to use estrogens in lactation inhibition except for women over 35 who experienced a surgical delivery. Alternative therapy is available for these women. The recently-developed drug, brom-ergocryptine, may replace other methods of lactation inhibition.

The rather exacting aesthetic requirements of dental restorations has largely dictated the composition of dental ceramic materials. The so-called dental porcelains have evolved from the traditional whiteware formula of feldspar, clay and quartz. One of the first variables which might be considered is that of chemical composition. It is, however, generally accepted that for ceramic materials small variations in composition are not critical. Since the early work of Watts in 1918, little interest has been expressed in the chemical composition of dental porcelain. The composition of traditional dental porcelains has evolved over a period of many years by practical trial and error, as discussed by Jones (1971). The development of dental porcelains advanced to the point where any major improvements in physical properties could only be achieved by major changes in composition and technique as advocated by McLean & Hughes (1965). The resulting alumina/glass composites which have been developed use a technique which involves the build up of an inner core which contains a high proportion of crystalline alumina (45-50 %) embedded in a glass matrix surrounded by a transparent outer veneer. This work compares the effect of such inter-related variables as composition, inclusion of filler, viscosity, texture, hardness, and strength of the fired product.

A simple abrasion test has been devised for evaluating composite and other restorative materials which have similar densities. The method grades the materials in order of their resistance to abrasion and the results for some composites are presented. The test makes use of a standard Wig-L-bug, the results being obtained by weight-loss.

Various factors which affect the strength of dental porcelain have been investigated. The variables studied include rate of loading, heat treatment, firing temperature, vacuum firing, specimen size, and span-to-depth ratio.

In a consecutive series of 250 cases of hydatidiform mole, the initial treatment was related to the mortality from subsequent malignancy. When hysterectomy was performed, either with the mole in situ (28 cases) or within 5 days of spontaneous or oxytocin-induced vaginal expulsion (46 cases) malignancy was detected in 6 cases and one patient died. When the hydatidiform mole was expelled vaginally, either spontaneously or following an oxytocin infusion and hysterectomy was not performed, 23 of 176 patients developed a malignant tumor, and 12 of them are dead. It is suggested that hysterectomy with ovarian conservation is protective against the subsequent development of malignancy and is the treatment of choice for patients, irrespective of age, who have a hydatidiform mole and who have no desire for further children.

Antibodies to both prostaglandin F (PGF) and prostaglandin E (PGE) were raised in rabbits after they were immunized with prostaglandin F2a conjugated to bovine serum albumin (PGF2a - BSA). The antisera were group specific although the antibodies to the F group of prostaglandins showed greater specificity than those to the E group. The antisera were sufficiently specific however to allow the direct radioimmunoassay of PGF and PGE in human semen and PGF in amniotic fluid during induced abortion. Specificity of the direct radioimmunoassay was checked by chromatographic separation of the prostaglandins prior to analysis. Estimation of the prostaglandins in the semen of 30 men attending the infertility clinic showed that 19 of the men had normal semen levels of PGE and PGF of 68± 7(SE) and 6.0 ±0.6 μg/ml respectively, as compared with data on normal fertile males, whilst the other 11 men had lower levels of 16 ±2 (SE) and 0.8±0.1 μg/ml respectively. Application of the method to amniotic fluid showed that the PGF concentration in amniotic fluid during the induction of abortion with extra-ovular saline increased from less than 0.6 ng/ml to 6.4 ng/ml when the induction-abortion intervals ranged from 6–48 hours.

Commercial refractory investments were examined to indicate thermal changes taking place by measuring: (1) the temperature accompanying the reaction of any change, and (2) the change in weight of the specimen. Use was made of differential thermal analysis, thermal gravimetric analysis, x-ray diffraction, and dilatometric methods. In the case of phosphate-bonded investments, particular attention was paid to both room-temperature and thermal bonding. A study was made of the decomposition of calcium sulfate in the presence of silica.

The effects of maternal age and social class on obstetric performance were analyzed in a study of 8692 primigravidae delivering in the Kuala Lumpur General Hospital 7898 of whom were from social classes 3-5 (General Section births) and 794 from social classes 1-2 (Bungsar Section births). The mean age at delivery was 21 years among those in the General Section compared with 26 years in the Bungsar Section. The mean birthweight in General Section births was 5.96 lbs for indians 6.25 lbs for Malays and 6.48 lbs for Chinese. In contrast mean birthweights in the Bungsar Section varied little by racial group (6.64 lbs indian 6.61 lbs Malay and 6.80 lbs Chinese). Preeclamptic toxemia occurred in 3.8% of Bungsar patients and 6.5% of General Section patients. The Cesarean section rate was higher among Bungsar patients (4.7%) than General Section population. After age 30 the perinatal mortality rate was 6 times higher among babies born to lower status mothers. The 6 maternal deaths occurring in this series all involved General Section patients. These results suggest that women of the highest socioeconomic groups under 30 years of age at ust pregnancy demonstrate the most efficient obstetric performance. Although the incidence of pregnancy complications increases significantly after age 30 in all social classes this disadvantage is partially offset in higher status women by better nutrition and medical care. It is concluded that older primigravidae should attend the antenatal clinic early in pregnancy be seen at frequent intervals and be given special attention during labor and delivery.