Haemodynamic Studies with Peruvoside in Human Congestive Heart Failure

The immediate haemodynamic effects of peruvoside, a cardiac glycoside obtained from the Indian plant Thevetia neriifolia Juss, were studied in six patients with congestive heart failure. The drug was found to have an immediate and powerful positive inotropic and negative chronotropic effect, like ouabain, on the failing human heart. Oral peruvoside was also effective in the treatment of congestive heart failure when used on a short-term as well as a long-term basis. It therefore seems that peruvoside is a useful cardiac glycoside in the management of congestive heart failure in man as a quick-acting intravenous preparation. It is equally effective when used orally.     

Pharmacokinetics of imipramine are affected by age and sex in rats

Chronic treatment with the antidepressant imipramine (IMI) leads to accumulation of imipramine's major metabolite desmethylimipramine (DMI) in the brain. Juvenile, young and middle-aged female rats, as well as juvenile and young male rats were treated chronically with imipramine (14 days) and analyzed 24 hours later for levels of IMI and DMI in the hypothalamus-preoptic area (HPA) and serum. Older animals of both sexes showed higher levels of DMI than juvenile animals, in both the HPA and serum. Females also had higher DMI levels than males at comparable ages. Analysis of IMI and DMI levels at intervals after a single imipramine injection suggested that the initial metabolism of imipramine is slower in older animals and in females (compared to males). The results indicate that age and gender alter the initial metabolism of imipramine, leading to enhanced accumulation of metabolites during chronic treatment in older animals and in female rats, compared to younger rats and males, respectively.     

A simple quantitative method for the estimation of free ecto-sulfhydryl groups of spermatozoa

A simple rapid quantitative method has been developed for the estimation of sperm ecto-SH groups on the basis of their high affinity binding to the mercurial: [203Hg]p-chloromercuriphenylsulfonic acid (PCMPS) used as a surface probe. The thiol reagent did not penetrate the sperm plasma membrane, as evidenced by the extremely rapid time course of the binding reaction and undetectable uptake of [203Hg]PCMPS by intact goat spermatozoa. The binding reaction was not due to contaminating broken or damaged cells, if any. The method consists of incubating of highly motile goat spermatozoa with PCMPS in a modified Ringer solution at 37 degrees C for 5 min, agglutination of the labelled cells with polyethyleneimine (100 micrograms/ml) and filtration and washing of the cell suspension through Whatman No. 1 filter discs under mild vacuum. The binding interaction is proportional to cell concentration, specific and saturable at 50 microM PCMPS. The method is capable of estimating free ecto-SH as low as 25 pmoles. Spermatozoa possess 286 +/- 61 pmoles of free ecto-SH groups/10(6) cells. Scatchard analysis showed the presence in goat spermatozoa of multiple classes of ecto-SH groups differing in their affinity for PCMPS.     

The use of 17O-NMR in the study of bond cleavage during the hydrolysis of sulphate esters

The use of 17O-NMR to investigate bond cleavage during the hydrolysis of sulphate esters in water enriched in 17O is described. Despite the inherent disadvantages of 17O for NMR studies, this work shows that, in favourable cases, 17O-NMR of 17O-enriched species is a powerful and sensitive tool for mechanistic studies. It is particularly useful when O-S cleavage occurs, resulting in the formation of S17O16O3(2-) (5% 17O), which can easily be detected at the biologically relevant mumole level. The method complements those using H2(18)O and has the advantage that in principle 17O can be detected in either of the hydrolysis products with little or no purification. It has been shown that sulphatase A (aryl-sulphate sulphohydrolase, EC 3.1.6.1) cleaves the O-S bond while functioning as a cerebroside sulphatase, as it does when functioning as an aryl- or glycosulphatase.     

Long-Timescale Molecular-Dynamics Simulations of the Major Urinary Protein Provide Atomistic Interpretations of the Unusual Thermodynamics of Ligand Binding

The mouse major urinary protein (MUP) has proved to be an intriguing test bed for detailed studies on protein-ligand recognition. NMR, calorimetric, and modeling investigations have revealed that the thermodynamics of ligand binding involve a complex interplay between competing enthalpic and entropic terms. We performed six independent, 1.2 μs molecular-dynamics simulations on MUP—three replicates on the apo-protein, and three on the complex with the pheromone isobutylmethoxypyrazine. Our findings provide the most comprehensive picture to date of the structure and dynamics of MUP, and how they are modulated by ligand binding. The mechanical pathways by which amino acid side chains can transmit information regarding ligand binding to surface loops and either increase or decrease their flexibility (entropy-entropy compensation) are identified. Dewetting of the highly hydrophobic binding cavity is confirmed, and the results reveal an aspect of ligand binding that was not observed in earlier, shorter simulations: bound ligand retains extensive rotational freedom. Both of these features have significant implications for interpretations of the entropic component of binding. More generally, these simulations test the ability of current molecular simulation methods to produce a reliable and reproducible picture of protein dynamics on the microsecond timescale.     

Evolutionary search: Gradients and information

To better understand evolution one might view evolution as a search algorithm proceeding through a search space. The search method implemented by reproduction with mutation and selection of the fit does not perform efficiently on many search spaces. Characteristics of the search space are critically important to the effectiveness of the search algorithm. The “gradients” of and the “information” in a search space are used in this paper to study performance of “evolutionary” search algorithms.     

Specific localization of 2′,3′-cyclic nucleotide 3′-phosphohydrolase, (Ca2+/Mg2+)-ATPase,and acetylcholinesterase in human erythyrocyte membrane

A procedure was developed for the detection of 2′,3′-cyclic nucleotide 3′-phosphohydrolase in myelin. This assay was sufficiently sensitive to detect the low levels of 2′,3′-cyclic nucleotide 3′-phosphohydrolase in human erythrocytes. The 2′,3′-cyclic nucleotide 3′-phosphohydrolase of human erythrocytes was determined to be exclusively associated with the inner (cytosolic) side of the membrane. Leaky ghostsand resealed ghosts were assayed for 2′,3′-cyclic nucleotide 3′-phosphohydrolase, (Ca²⁺/Mg²⁺-ATPase, and acetylcholinesterase activity, and the 2′,3′-cyclic nucleotide 3′-phosphohydrolase profile is the same as that of the (Ca²⁺/Mg²⁺)-ATPase, an established inner membrane maker.     

Standardized model for diagnosing cervical carcinoma in situ based on the cytologic signs

An attempt was made to optimize the recognition of cervical intraepithelial carcinoma in situ (CIS) by the adoption of a standard set of rules derived from a case-control study of 50 histologically confirmed incidence cases of CIS and a simple random sample of 100 controls from the same mass screening population examined between 1977 and 1984. One cytotechnologist screened the slides for all occurrences of a standard set of classic cytopathologic signs. Chromatin clumping, dyskeratosis, anisonucleosis and an increased nuclear-cytoplasmic ratio in cells from the deep layer and chromatin clumping and anisonucleosis in cells from the superficial layer showed an association with the diagnosis of CIS, in decreasing order of magnitude. These variables make up a binary discriminant model; adding vacuolization, anisocytosis, prominent nucleoli and multinucleation to this model did not appear to improve its discriminatory power. The discrimination function accommodates any a priori judgment regarding the probability and utility of diagnostic outcomes. Cytologists normally manipulate the probabilities and utilities intuitively; the model requires the translation of intuitive judgments into quantitative estimates. For example, in our cytology laboratory, the CIS pick-up rate is approximately 1 per 1,000 smears; a 1:1,000 negative utility ratio of a false positive versus a false negative is thus used in our model. Given this, our model has a sensitivity of 86% and a specificity of 96% upon reclassification, and its predictive power (true positives/false positives) is 21.5. This standardized cytodiagnosis model is relevant to any local diagnosis-specific probability and utility estimates.     

Interacting role of thyroxine and growth hormone in the hepatic synthesis of alpha 2u-globulin and its messenger RNA

Hypophysectomy completely abolishes and thyroidectomy results in a 90% reduction in the hepatic content of alpha 2u-globulin and its mRNA in the male rat. Thyroid hormone is also known to be required for the synthesis and secretion of pituitary growth hormone. In the hypothyroid rat either thyroxine or growth hormone was found to increase the activity and number of sequences of the mRNA for alpha 2u-globulin (measured by translational assay and hybridizational analysis with a cloned cDNA probe) to the euthyroid level. Treatment of hypophysectomized rats with a hormone combination containing growth hormone but not thyroxine increased the hepatic level of the mRNA for alpha 2u-globulin to that of normal animals. From these results we conclude that thyroxine indirectly influences the hepatic concentration of the mRNA for alpha 2u-globulin through its effect on pituitary growth hormone. Although administration of growth hormone to hypothyroid animals raised the hepatic concentration of alpha 2u-globulin mRNA to the euthyroid level, synthesis of alpha 2u-globulin remained low (50% of the normal). Complete recovery of alpha 2u-globulin synthesis required thyroxine. Therefore, in addition to an indirect effect on the hepatic level of alpha 2u-globulin mRNA, thyroxine also directly influences the synthesis of this protein. This direct effect of thyroxine on alpha 2u-globulin synthesis seems to be exerted at a step distal to the formation of mature mRNA.