Stoichiometric noncovalent interaction in molecular imprinting.

In this review article the function of the binding site monomers in the molecular imprinting procedure is discussed. Especially, new developments towards stoichiometric noncovalent interactions are highlighted. In stoichiometric noncovalent interactions template and binding site monomer in an 1:1 molar ratio are nearly completely bound to each other. This is only possible if the association constants are considerably high (Kass > 900 M(-1)). Using this type of interaction in molecular imprinting no excess of binding sites is necessary and binding sites are only located inside the imprinted cavity. Since all cavities can be reloaded these polymers show high capacity (e.g., for preparative application) and are especially suited for the synthesis of catalytically active imprinted polymers. Discussed are binding site interactions based on amidines (and guanidines), multiple hydrogen bonding, charge-transfer interactions, and host-guest inclusion. The systematic investigation of the underlying binding reaction is described in detail. With low-molecular weight model substances the thermodynamics of the association can be conveniently investigated, e.g., by NMR spectroscopy.

Imprinting techniques in synthetic polymers--new options for chemosensors.

Highly selective molecular recognition in synthetic polymers may be the basis for a new type of chemosensor. For the preparation of such polymers, a molecular imprinting procedure during crosslinking is used to generate, with the aid of template molecules, microcavities of specific shape and with a defined arrangement of functional groups. In this review the role of the polymer matrix and the type of binding site interaction is discussed in more detail. Recent attempts to use these polymers as the basis for chemosensors are highlighted.

Management of uterine perforation following elective abortion.

Experience is reported with 28 uterine perforations encountered from June 1, 1973, to June 1, 1976, among 20,000 first trimester abortion patients at Reproductive Health Services, St. Louis, Missouri. In order to prevent this complication, one must perform an exacting pelvic examination. The use of a sound is controversial. Dilators should be introduced only a short distance through the internal os, and as much of the products of conception as possible should be aspirated. A sharp curette should be diagnostically. Various questions should be asked before the operator constructs a scheme for managing perforation. The current policy for management used at this clinic is outlined.

PIP: 28 uterine perforations occurred from June 1, 1973, to June 1, 1976, among 20,000 first trimester abortion patients at Reproductive Health Services, St. Louis, Missouri. The management of such perforations should depend on the site of the perforation and the completeness of the abortion. These questions should also be answered: 1) How many weeks pregnant is the patient? 2) Is there extragenital injury? 3) Is there hematoma formation or evidence of continuing intraperitoneal blood loss? The laparascope is valuable in evaluation of the perforation damage and in determining if laparatomy is necessary. If bleeding is extensive, laparotomy is indicated for uterine and vessel repair which may even involve hysterectomy. If the perforation is discovered before removal of all products of conception, the plan depends on the site of the perforation. If vital signs are steady either 1) the patient may be returned to the procedure room and a 2nd evacuation performed, avoiding the area of perforation; or 2) the patient may be admitted to hospital for laparascopic study and evaluation for a 2nd vaginal evacuation. If perforation seems to be lateral, with intraabdominal bleeding, the patient should be hospitalized at once for close observation.

Elective abortion. Complications seen in a free-standing clinic.

Experience is reported with the elective first trimester abortion of 16,410 pregnancies during a 31-month period by Reproductive Health Services of St. Louis, a free-standing clinic. Incidence of complications was 1.54%. The most common of these were incomplete evacuation, excessive postabortal bleeding, and uterine perforation. In patients with unquestioned perforation, the use of laparoscopy has been very valuable in ascertaining the exact nature of the perforation, in avoiding unnecessary laparotomy, and in giving intraabdominal visual guidance to concomitant suction evacuation in cases of an incomplete procedure. Aspects of the other complications are also discussed. In general, the findings support the view that even in the first trimester, the earlier in pregnancy that suction abortion is performed, the less likely it is to result in major complications. It is possible to perform first trimester abortions in a free-standing clinic with a satisfactorily low complication rate.

PIP: In elective first trimester of 16,410 pregnancies between June 1973-January 1976 at Reproductive Health Services of St. Louis, incidence of complications was 1.54%. The most common complication (32% of total complications) was incomplete evacuation of the uterus. Perforations of the uterus occurred in 34 patients (.2%); 1/3 of the perforations occurred in primigravidas. Excessive postabortal bleeding occurred in 41 patients and cervical lacerations in 22. 11 patients developed postabortal syndrome (PAS). In patients with unquestioned perforation, the use of laparoscopy is valuable in ascertaining the exact nature of the perforation, in avoiding unnecessary laparotomy, and in giving intraabdominal visual guidance to concomitant suction evacuation in cases of an incomplete procedure. The earlier that suction abortion is performed, the less likely it is to result in major complications; 56% of the complications occurred after the 10th week of pregnancy which represented 36% of the total procedures.

Apolipoproteins in human pregnancy.

Apolipoproteins are important in the structure and metabolism of lipoproteins, and alterations in levels of apoproteins or in their interrelations occur in some forms of hyperlipemia. Pregnancy is regularly accompanied by hyperlipoproteinemia, but while data on lipoprotein lipids is available, the apopipoproteins have not been studied. To characterize the lipemia of pregnancy more completely, we studied some of the apolipoproteins in plasmas of pregnancy women. Thirty-eight normal fasting women were studied between the 18th and 39th weeks of gestation and again 23 plus or minus 17 weeks after delivery. Eight additional women were sampled every 4-6 wk during the second and third trimesters of gestation. Plasma and lipoprotein lipids were assayed by standard procedures and Apolipoprotein B (ApoB) was measured by radioimmunoassay. The interrelations of Apolipoprotein A (ApoA) in high-density lipoprotein (HDL) and of Apolipoprotein C (ApoC) in very-low-density lipoprotein (VLDL) were assessed by disc gel electrophoresis in four women during the last trimester of gestation and again 6-8 mo post partum and in four nongravid controls. Gestational triglycerides (TG) and cholesterol (Chol) were elevated in 95% of the pregnant women. TG in lipoproteins rose progressively during gestation, with VLDL-TG rising the most. Low-density lipoprotein (LDL) and HDL became enriched by TG relative to other components. Total-and VLDL-ApoB increased, while LDL-ApoB remained unchanged, resulting in a change in the density distribution of ApoB. (VLDL-ApoB X 100/total ApoB rose from 3.6% to 6.7%, P less than 0.02.) The accumulation of TG-rich LDL and the increases of VLDL-ApoB may be the result of changes in the rates of secretion or intravascular catabolism of VLDL. Which process is altered remains to be determined. The relative amounts of ApoC-II and ApoC-III in VLDL and the ApoA-I/ApoA-II ratios in HDL were unchanged in pregnancy. These results differ from those seen following high-carbohydrate diets.