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The polymerase chain reaction (PCR) is a powerful new method for 'in vitro cloning'. It can selectively amplify a single molecule of template DNA several millionfold in a few hours and has made possible new approaches to problems in molecular genetics, evolutionary biology, and development.

Tables are presented for the critical value, power and sample size required to attain a given power at a given alternative for the likelihood ratio statistic for testing H"0: @q = @q"0 versus H"1: @q = @q"1 > @q"0, where @q is the mean of a normal distribution having variance a^[email protected]^2 with the coefficient of variation, a, assumed known.

The level of expression of a β-lactamase human preproinsulin fusion protein1 in Escherichia coli was increased by plasmid and host manipulations. The initial expression level (0.01% of total protein) was increased two- to three-fold by replacing the p-lactamase promoter with two strong promoters: trp from Serratia marcescens and lacUV5 from E. coli. Replacement of the β-lactamase ribosome binding site (RBS) with a trp RBS enhanced the yield to a total of 0.16% of the total cell protein. Proinsulin was unstable, with a half-life of 14 minutes at 37°C. Proinsulin expression was increased three-fold (to about 0.5% of the total cell protein) by incubating the host at 30°C rather than 37°C.

A FEW years ago, Crumpton1 and Reichlin2 reviewed information about the antigenic structure of globular proteins of known amino acid sequence and three-dimensional structure. It seemed that only a small fraction of the amino acid residues in such proteins participated directly in antibody binding. This impression was reinforced by Atassi and co-workers, who proposed antigenic structures of two such proteins—sperm whale myoglobin3 and chicken lysozyme c (ref.4). These workers claim to have identified all those amino acid residues which bind to antibodies present in antisera directed against the protein. These claims stem from extensive studies with chemically modified forms of the protein as well as with antigenically active fragments obtained by specific cleavage of the protein. The antigenic residues are arranged in groups called determinants, each of which binds a specific class of antibodies. A typical determinant contains four to seven residues. For both lysozyme and myoglobin, the proportion of antigenic residues is about 15% of the total number of amino acid residues in the protein3,4. Information has also accumulated concerning the power of antisera to detect evolutionary substitutions of amino acids in globular proteins. Quantitative immunological comparisons of related proteins of known amino acid sequence have consistently shown a strong correlation between degree of sequence difference and degree of antigenic difference. This has been demonstrated most thoroughly for monomeric globular proteins such as lysozymes5,6, ribonucleases7, azurins8 and cytochromes c (refs 9, 10). Less complete information suggests that the correlation holds also for plastocyanins10, tryptophan synthetase α subunits11, serum albumins12, carbonic anhydrases and myoglobins13 (A. B. Champion, E. M. Prager, S. L. Welch, and A. C. Wilson, unpublished), and ferredoxins14. From the strength of the correlations observed for lysozymes, ribonucleases, azurins and cytochromes (r > 0.9), one may make the statistical inference that about 80% (that is, 0.9 squared) of those amino acid substitutions which accumulate during evolution are immunologically detectable7. Here we summarise additional evidence that the majority of evolutionary substitutions are immunologically detectable, and we discuss how to reconcile this evidence with the chemical evidence that only a small fraction of the amino acids are antigenic.

Neuronal activity of 58 cells in the lateral nucleus of the amygdala of freely moving cats was studied across stages of sleep-wakefulness. In general, these units were very slow firing in all states (mean discharge rate less than 1 spike/sec) with the highest rates typically observed during slow wave sleep and paradoxical sleep. Most units tended to show some bursting activity during all states. The bursting during paradoxical sleep was not temporally correlated with the phasic activity characteristic of that state. These results corroborate and extend previous studies of the basal amygdaloid nuclei.

To study in detail the effects of percutaneous nephrolitholapaxy on renal function, a consecutive series of 11 patients were investigated preoperatively by excretory urography, gamma camera renography for determination of individual renal function and computerized tomography of the kidneys. Postoperatively, gamma camera examination, computerized tomography, antegrade nephrostography, renal angiography and excretory urography were performed. With 2 exceptions, percutaneous nephrostomy, dilation of the tract and stone removal were done in 1 stage with the patient under continuous epidural anesthesia. Nephrostomy tract dilation was done with an Olbert type balloon catheter or Alken metallic dilators. Thickening of Gerota's fascia was demonstrated by computerized tomography in most cases, and small to moderate perirenal hematomas were found in several. At gamma camera examination decrease of renal function was noted regularly on postoperative day 1 and returned to near initial levels 2 weeks postoperatively in most cases. Angiography in 10 patients showed discrete parenchymal scarring in some and a peripheral arteriovenous fistula in 1. We conclude that percutaneous renal stone surgery usually is tolerated well by the kidney.

To examine the effect of amino acid substitutions in lysozyme on the binding of antibodies to lysozyme, we purified lysozyme from the egg whites of California quail and Gambel quail. Tryptic peptides were isolated from digests of the reduced and carboxymethylated lysozymes and subjected to quantitative analysis of their amino acid compositions. The two proteins were identical by this criterion. Each peptide from the California quail lysozyme was then sequenced by quantitative Edman degradation, and the peptides were ordered by homology with other bird lysozymes. California quail lysozyme is most similar in amino acid sequence to bobwhite quail lysozyme, from which it differs by two substitutions: arginine for lysine at position 68 and histidine for glutamine at position 121. California and bobwhite quail lysozymes were antigenically distinct from each other in quantitative microcomplement fixation tests, indicating that substitutions at one or both of these positions can alter the antigenic structure of lysozyme. Yet neither of these positions is among those claimed to account for the precise and entire antigenic structure of lysozyme [Atassi, M. Z., & Lee, C.-L. (1978) Biochem. J. 171, 429--434]. Two possible explanations for this discrepancy are discussed.

Evolutionary genetics has two parallel thrusts: the reconstruction of phylogenies and the analysis of populations. Since 1962, when Zuckerkandl and Pauling1 proposed that comparison of the sequences of proteins and genes could be used as a molecular clock to date the divergence of extant species, a variety of biochemical methods has been used for phylogenetic studies. Electrophoretic analysis of isozymes, immunological comparisons, and protein sequencing were extensively used in the first two decades and, more recently, DNA-DNA hybridization and ribosomal RNA sequencing have made a major contribution to systematics.2 Most of these techniques are limited because they estimate sequence difference instead of measuring it directly.

Needle biopsies of the liver were performed on 30 patients with heart failure and correlated with clinical features and biochemical liver function studies. Hepatic biopsy served as a useful adjunct to other methods in deciding the status of the liver in this group. Type of heart disease, degree of heart failure and length of heart failure could not be correlated with the observed histology. Neither history, physical examination, nor biochemical functional studies provided sufficient information to predict anatomy with certainty. A histologic diagnosis improved both therapeutic and prognostic perspective.

Hepatic abnormalities constitute common and important secondary effects of congestive heart failure. Considerable information has been accumulated on the liver in heart failure, including anatomic changes, 1–10 biochemical alterations, 11–18 and physiologic disturbances. 19 The present report is based on histologic studies of the liver correlated with clinical and biochemical findings in seventy-five patients with congestive heart failure. The investigation was undertaken to further the evaluation of the mechanism and significance of hepatic abnormalities in chronic circulatory congestion.

CONSIDERABLE information has been accumulated on the pathogenesis, 1 anatomical changes, 2 biochemical alterations, 3 and treatment 4 of fatty liver in man and in laboratory animals. This paper will record our experiences with 102 patients in whom aspiration biopsy of the liver revealed fatty metamorphosis without fibrosis. Attention is directed to etiological factors, clinical and biochemical findings, response to treatment, and sequelae of the fatty liver. MATERIALS AND METHODS There were 77 men, 24 women, and 1 child. Ages ranged from 4 to 77 years. Eighty-six patients had consumed alcoholic beverages excessively; 21 of these were admitted for delirium tremens. In this group, 11 patients were obese, 7 had diabetes mellitus, 4 had peptic ulcer, 2 had chronic pulmonary disease, and 1 had hypertensive heart disease. Sixteen patients did not use alcohol. Four patients in this group had diabetes mellitus, four had malignant neoplasms, and 3 had cholecystitis; obesity, plumbism, inanition, carbon tetrachloride