Early intrauterine development: I. The rate of growth of Caucasian embryos and fetuses between the 6th and 20th weeks of gestation.

Liberalization of abortion laws in various countries and states of Europe and America has offered an opportunity for the study of the correlations between menstrual age and the rate of bodily development of human embryos and fetuses. In several institutions where local bylaws mandated the consent of the patients requesting therapeutic abortion to pathological investigation of the products of conception, various parameters of growth were measured systematically. These included crown-rump and foot lengths and body weight. The analysis of the data indicated that in the embryosic stages of development the rate of growth is substantially slower than it had been assumed previously. In the more advanced fetal stages of development the findings supported the validity of the long-established standard of Streeter. Since the current study has been based on apparently normal gestations of healthy women, whereas earlier data had rested, to a great extent, on spontaneously aborted and extopic embryon and fetuses, it seems evident that pathological specimens are not suitable for the purpose of establishing reliable standards of normal intrauterine growth rate. The present data support the suggestion, based on various experimental and clinical observations, that pathological gestations often result from abnormal ovulations that occur at times other than the mid-cycle and that such conceptions are frequently followed by a bleeding episode that simulates menstruation. It is likely that the inclusion of a high number of such cases biased the results of earlier investigations concerning embryonic growth rate on account of the frequent incidence of erroneous menstrual histories. The material available did not permit the extension of the investigation beyond the 20th week of gestation. It appears, however, that the average growth rate in the mid-trimester may be slower than the data adopted by the American Academy of Pediatrics would indicate. The possible causes of some phenomena observed in the course of the investigation, such as unexplained scatter of growth-rate patterns at all developmental stages and discrepancies among various literary data, have been discussed in some detail. While a tentative attempt has been made to correlate the investigated parameters of fetal growth with biparietal diameters of the head, a measurement accessible to direct assessment by sonography during pregnancy, the necessity of improving these standards through a prospective study has been emphasized.

Early intrauterine development: II. The rate of growth in Black and Central American populations between 10 and 20 weeks' gestation.

The application of the growth-rate standards, extablished for Caucasian embryos and fetuses in a previous report, to Black and Central American racial groups has been investigated. Comparison between menstrual age and crown-to-rump length indicated differences in the 10 to 15 weeks' gestation range. However, growth rates for the same groups were practically identical between the 15th and 20th weeks of pregnancy. This finding suggests that the actual rate of growth is closely similar in the respective ethnic groups and that apparent discrepancies reflect erroneous, or purposefully false, menstrual histories rather than dissimilar growth patterns. Largely identical rates of development were suggested by the crown-rump length to foot length to body weight interrelations among the various racial groups. A moderate, but rather predictable, deviation from the earlier established standards was noted in the crown-rump length versus foot length ratios of Black American fetuses, providing the only exception to what appears to be a practically identical rate of growth for the investigated ethnic groups in the first half of gestation. The evaluation of the results was extended to involve the effect of educational and social factors on currently available data of embryonic and fetal growth. It is suggested that heretofore unconsidered factors may affect the validity of widely quoted standards of intrauterine growth.

Steady-state lithium blood level fluctuations in man following administration of a lithium carbonate conventional and controlled-release dosage form.

A controlled-release lithium carbonate tablet was compared to an immediate release lithium carbonate capsule in normal volunteers. These crossover studies at steady state showed that the tablet produced a smoother serum curve than the capsule with no loss of total bioavailability. Quantitatively, the capsule produced about 1.4 times more fluctuation in serum lithium values than the tablet.

Peroperative microbial contamination of anterior chamber aspirates during extracapsular cataract extraction and phacoemulsification.

BACKGROUND: The normal conjunctival flora is one of the main sources of intraocular contamination during cataract surgery. The theory that the positive anterior chamber (AC) pressure during phacoemulsification (phaco), and the smaller wound utilised, might reduce the rate of contamination was studied. METHODS: The peroperative AC aspirates of 210 consecutive patients undergoing cataract surgery were assessed. In group 1, 100 patients underwent a standard extracapsular cataract extraction (ECCE). In group 2, 110 patients underwent phacoemulsification of the crystal-line lens through a scleral tunnel. AC aspirates from the Simcoe irrigation/aspiration cannula (group 1) and phaco probe (group 2) were collected and microbiological studies performed after direct and enrichment cultures. RESULTS: There were 29 (29%) positives in the ECCE group compared with 22 (20%) positive cultures from AC aspirates in the phaco group. Coagulase negative staphylococcus (CNS) was the commonest contaminant in both groups. CONCLUSION: Although there was a higher rate of AC contamination during ECCE, the difference was not statistically significant (p > 0.10, chi 2 = 2.31).