Isolation of ribonuclease-free polysomes from human placenta

Human placenta is known to have a high level of polysome-bound ribonuclease which has hindered the isolation of intact polyribosomes from this tissue. We describe conditions for preparing polysomes devoid of apparent ribonuclease activity from both first trimester and term placenta. This stable preparation was achieved by utilizing buffer at low pH containing 300 mM LiCl and precipitating the polysomes chemically with 200 mM MgCl2. The yield of polysomes obtained by this procedure is 2-2.5 fold greater than that obtained by the conventional method of preparing placental polysomes. The polysomes are considered pure as judged by the ratios of absorbance 260/280 and 260/235. Moreover, the yield of polysomes obtained is greater than 95% of the tissue content and the profile of the polysomes is probably representative of the in vivo population. This is concluded from experiments in which a known amount of labelled chick polysomes was added to fresh placental tissue and the recovery of label and its distribution was analyzed.

Metabolic pathways coupled to H+ transport in turtle urinary bladder

Active H+ transport in the turtle urinary bladder is mediated by an ATPase. Although the source of ATP is usually mitochondrial oxidative phosphorylation, it is possible because of intracellular compartmentalization or cellular heterogeneity that one metabolic pathway exclusively provides ATP to the pump. To examine this we performed several types of experiments. In one, the coupling between the rate of transport and the rate of oxidation of 14C-labeled substrates was studied. We found that there was coupling between H+ transport and glucose, butyrate oleate, and beta-OH-butyrate oxidation. In another set of experiments we depleted turtle bladders of their endogenous substrates and tested the effect of a number of substrates on the rate of transport. We found that glucose, pyruvate, lactate, actetate, butyrate and beta-OH butyrate all stimulated H+ transport. In a third set of experiments we found no coupling between H+ transport and lactate production. Finally, we found that reduction of H+ transport by mucosal acidification resulted in an increase in epithelial cell ATP concentrations and a decrease in ADP levels. These results suggest that the H+ pump receives its ATP from carbohydrate and fatty acid oxidation. The changes in ATP and ADP levels provide an initial explanation for the coupling of H+ transport to the rate of cellular oxidative metabolism.

Fluorimetric assay of acid lipase in human leukocytes

A fluorimetric assay for leukocyte acid lipase, the enzyme defect in Wolman disease, is described. The method requires a smaller volume of blood and can be performed more rapidly than the present colorimetric assay for the leukocyte enzyme.

Glutathione peroxidase in dried blood spots

A new procedure utilizing dried blood spots was developed for detecting glutathione peroxidase deficiency. Samples from a known patient with a partial defect and from rats with an induced deficiency were distinguished from respective control groups by their longer defluorescence endpoints. Samples from 100 patients with anemia and 2 phenyl-ketonuric infants on low-protein diets contained glutathione peroxidase activity similar to that in 82 controls, when screened for the enzyme defect by the new procedure.

Rapid identification of San Filippo disease (MPS III)

Humbel's thin-layer chromatography of urine was a rapid, reliable means of identifying type of mucopolysaccharide storage disease in 30 patients. Over half had Hurler-Scheie or Hunter disease (MPS I-V or II); eight had San Filippo disease, of which four expressed the Type B form.

Cystinuria genotypes predicted from excretion patterns

Genotypes of 17 patients with cystinuria were predicted from data based on excretion rates of the families' obligate carriers. The methodology differed from that used by other investigators as it did not employ intestinal biopsy studies or loading dose measurements. The Type I form was more common than either Type II or Type III and frequently occurred in combination to give compound heterozygous genotypes with the Type III form.

The use and preliminary results of the Troutman surgical keratometer in cataract and corneal surgery

The Troutman microsurgical keratometer has been shown to be useful in monitoring intraoperative procedures, and it has been demonstrated in the case of cataract and keratoplasty to have a significant influence on the control of operatively induced astigmatism. It is applicable to any surgical procedure which has the potential of altering permanently and unpredictably the corneal curvatures. Intraoperative keratometry has clearly demonstrated some inadequacies of our current cataract and keratoplasty techniques. It is now being used to guide our efforts toward a more rational control of the vexing problem of astigmatism.