Acetylcholinesterase and butyrylcholinesterase activity in the human term placenta: implications for fetal cocaine exposure

The characterization of the enzymes responsible for drug metabolism in the human placenta is of great importance in determining the possible role the placenta plays in protecting the fetus from potentially fetotoxic drugs. We speculate that the placenta metabolizes cocaine, serving to protect the fetus from the drug's ill effects. Cholinesterase, the principle enzyme that metabolizes cocaine, has been hypothesized to be present yet is not well characterized in the human placenta. The purpose of this study was to quantify human placental acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity. Human placentas were obtained from elective cesarean sections, and several lobules were thoroughly perfused with cold buffer to ensure minimal contamination from erythrocyte AChE. Subcellular fractions were then prepared from these lobules by using standard differential centrifugation techniques. Microsomes and cytosol were assayed for AChE and BChE activity by using a spectrophotometric assay. BChE activity was found in the cytosolic fraction of the placental villous tissue, whereas AChE activity was measured in the microsomal fraction. By demonstrating that BChE activity is present in human term placenta we have shown that this organ has the capacity to metabolize cocaine and may therefore serve as a metabolic barrier to fetal exposure to cocaine.

Local blood-brain barrier in the newborn rabbit: postnatal changes in alpha-aminoisobutyric acid transfer within medulla, cortex, and selected brain areas

Postnatal changes in local permeability of the blood-brain barrier to an inert neutral amino acid (alpha-[14C]-aminoisobutyric acid) were investigated in 25 rabbits. The local transfer constant (K) for this tracer was measured with quantitative autoradiographic techniques at postnatal ages of 1, 3, 8, and 17 days, and adult. In adults, the amino acid penetrated the blood-brain barrier poorly in most regions examined (K less than 1 microliter.g-1.min-1) except within and in proximity to structures with a relatively leaky blood-brain barrier such as area postrema and choroid plexus. The rate of tracer entry into "impermeable" regions was seven- to 10-fold greater in 1-day-old rabbits than adults and not dependent on active transport. In young animals, there was a pronounced regional variation in K with the lowest values occurring in white matter and the highest in gray matter such as cerebral cortex, posterior thalamus, and hippocampus. During postnatal development, K decreased (p less than 0.01) with most regions having values near those of adults by 17 days of age. The results indicate that the blood-brain barrier of the newborn rabbit is relatively leaky to a small hydrophilic nonelectrolyte with a distribution that is heterogeneous regionally. Irrespective of age, such blood-borne substances can accumulate in certain brain areas considered to have impermeable vessels (e.g., nucleus tractus solitarii).

Toxicity of WR-2721 administered in single and multiple doses

Two hundred forty-three patients have received WR-2721 in Phase I-II studies. Separate studies were conducted in which patients with advanced malignancies received WR-2721 before single or multiple doses of radiotherapy or in single doses prior to cyclophosphamide, nitrogen mustard or cis-platinum. Single doses were escalated from 25 to 1330 mg/m2. An Acceptable Tolerated Dose (ATD) of 740 mg/m2 infused in 15 minutes has been established and is currently used in Phase II studies. Significant persistent hypotension (greater than 20 torr systolic) as a dose-limiting toxicity has occurred in 5% of patients in the single dose study. Fifty-five patients have been entered in the multiple dose trial. Dose levels of 340 mg/m2, four times a week for three weeks, and 250 mg/m2, four times a week for six weeks have been reached. There were five idiosynchratic reactions (fever, chills, rash, hypotension), one of which was severe. Some patients withdrew from the multiple dose study because of vomiting after each injection, or fear. No deaths nor any long-term untoward effects were observed. There is no suggestion of tumor protection.

[Effect of glutaraldehyde on the species-specific antigenicity of xenogeneic cartilage]

Present results showed that an extract of xenogeneic cartilage may inhibit the complement activity of human serum, while an extract of xenogeneic cartilage treated with glutaraldehyde may enhance this effect. This finding suggested that treatment with glutaraldehyde does not decrease species-specific antigenicity of xenogeneic cartilage.

[Species-specific antigenicity of xenogeneic bone treated with glutaraldehyde]

Present results showed that an extract of xenogeneic bone may inhibit the complement activity of some human sera, while an extract of xenogeneic bone treated with glutaraldehyde may show a lower inhibiting effect. This finding suggested that a preventive treatment in vitro with glutaraldehyde significantly decreases species-specific antigenicity of bone tissue.

Osteosclerosis in leprosy

The literature contains little reference to the phenomenon of osteosclerosis in leprosy. The aim of the authors' investigations was to determine: a) the incidence of osteosclerosis as part of the radiographic picture in the distal extremities of the limbs; b) the pathological substratum; c) the possible clinical significance. The research was carried out on 233 leprosy patients at the Colonia Hanseniana di Gioia del Colle (Bari). The authors examined 260 radiographs of the hands and 1310 radiographs of the feet. A number of biopsy samples of bone were taken from four patients and examined by means of microradiography using ultraviolet fluorescent light and also by historadiography. The basic radiographic features indicative of osteosclerosis were: a) reactive osteosclerosis; b) sclerosing periostosis; c) massive osteosclerosis. The authors observed a preponderance of osteosclerosis in the bones of the first digital ray, both in the phalanges and metatarsals or metacarpals. The sesamoid bones were affected more commonly in those of the first digit than those of the fifth. The radiographic findings were confirmed microscopically. It is difficult to assess the possible clinical significance because of the transient nature of the osteosclerosis in the evolution of the lepromatous lesions with time.