High-frequency switching in Dictyostelium

A high-frequency switching system is demonstrated to exist in Dictyostelium discoideum. Switch phenotypes are distinguished by colony morphology and include changes in developmental timing as well as blocks in morphogenesis. The switching system exhibits the following characteristics: (1) a "low" spontaneous frequency of switching (approximately 10(-2] in the parent strain; (2) stimulation of the basal level of switching roughly fivefold with low doses of ultraviolet light; (3) "high" spontaneous frequencies of switching (as high as 10(-1] in particular variant strains; (4) high spontaneous frequencies of interconvertibility between variant phenotypes; (5) high spontaneous frequencies of reversion to the wild-type phenotype; (6) a set of reproducible switch phenotypes; (7) heritability of switch phenotypes; and (8) a rough correlation between switch phenotype and switching frequency. The extraordinary similarity between the switching systems in D. discoideum and Candida albicans is discussed.

Distribution of receptors for insulin and insulin-like growth factor I (somatomedin C) in the adrenal gland

Rat adrenal glands contain cell surface high-affinity receptors for several peptide hormones. Receptors for IGF-I were abundant in this tissue, but receptors for insulin were relatively scarce. The behavior of adrenal membrane IGF-I receptors in radioligand binding assays was similar to the behavior of IGF-I receptors from other tissues, with a KD congruent to 6.2 x 10(-9) M. Covalent cross-linking studies with [125I]IGF-I revealed an IGF-I receptor alpha-subunit with Mr congruent to 135,000 on dodecyl sulfate polyacrylamide gel electrophoresis under reducing conditions, as well as a smaller radiolabeled peptide, Mr = 116,000. In contrast, little binding of [125I]insulin to adrenal membranes was observed and no labeling occurred in cross-linking studies using [125I]insulin. These results contrast with the findings of whole-body autoradiographic studies that indicated substantial binding of [125I]insulin to adrenal glands and suggest that IGF-I, rather than insulin, may play a critical role in the growth and development of the adrenal gland.

Distribution-free estimation of age-related centiles

A method is described for calculating age-related centiles which makes no assumption about the nature of the distribution of the measurement at a fixed age.

Characterization and mapping of the Bacillus subtilis prtR gene

A gene from Bacillus natto encoding a 60-amino-acid peptide has been previously described that, when cloned on a high-copy plasmid in B. subtilis, enhances production of alkaline protease, neutral protease, and levansucrase. An identical gene was isolated from B. subtilis and caused a similar phenotype when placed on a high-copy plasmid. Genetic mapping localized this gene near metB, distant from other pleiotropic genes causing similar effects. Deletion of this gene from the B. subtilis chromosome had no obvious phenotypic effect.

CSF brain creatine kinase levels and lactic acidosis in severe head injury

The posttraumatic creatine kinase-BB isoenzyme (CKBB) activity and lactate concentration in ventricular cerebrospinal fluid (CSF) have been studied in 29 patients with severe head injuries. The CKBB activity reaches its maximum a few hours after trauma, and has a monoexponential drop with a half-time of approximately 10 hours. Ventricular CSF lactate concentration continues to rise in patients with a poor outcome, and decreases only slowly and inconsistently in most of the other patients. Thus, increase of lactate in the ventricular CSF is not, like CKBB, a direct one-stage consequence of the trauma but is due to continuous production from a derangement of metabolism caused by the trauma. Since even higher ventricular CSF lactate levels can be survived when not caused by head injury, and since no significant pH changes were related to the ventricular CSF lactic acidosis in these artificially ventilated patients, it is concluded that ventricular CSF lactic acidosis is indicative of a severe, although not necessarily intractable, disturbance of brain function associated with intracellular lactate production and acidosis.

Identification of the pleiotropic sacQ gene of Bacillus subtilis

The sacQ gene of Bacillus subtilis, a pleiotropic gene affecting the expression of a number of secreted gene products, has been identified as a small 46-amino-acid polypeptide. The increased expression of this polypeptide in strains carrying the sacQ36 allele, or in strains carrying the sacQ gene on a high copy plasmid, appears to be responsible for the phenotype of higher levels of proteases seen in these strains. A deletion of the sacQ gene had no apparent phenotype, indicating that it is not an essential gene.

Nucleotide sequence of the amylase gene from Bacillus subtilis

The gene coding for amylase (EC.3.2.1.1) has been isolated and sequenced from Bacillus subtilis by cloning in lambda Charon4A and pBR322. The entire coding sequence and large preceding and following regions, comprising the presumed transcriptional and translational regulatory regions, were sequenced. The coding sequence shows a large open reading frame with a translated molecular weight of 72,800 and a presumed signal sequence of approximately thirty-two amino acids. When the intact gene is present in Escherichia coli, it confers the ability to degrade starch, indicating that the gene is expressed in a functional state.

Fine structure and evolution of the rat serum albumin gene

The exons, their boundaries, and approximately half of the intronic deoxyribonucleic acid of the rat serum albumin gene were sequenced. In addition to the 14 exons identified earlier by R-loop analysis, a small exon was detected between the "leader" exon (Z) and exon B. The leader exon encoded the 5'-untranslated portion of albumin messenger ribonucleic acid and the "pre-pro" oligopeptide present on the nascent protein. The sites of initiation and termination of transcription were tentatively identified by comparison of the 5' and 3' gene-flanking sequences with those of other eucaryotic genes. All 28 intron/exon junctions conformed to the "GT-AG rule" (Breathnach et al., Proc. Natl. Acad. Sci. 75:4853-4857, 1978). The three homologous domains of albumin were encoded by three subgenes that consisted of four exons each and evolved by intragenic duplication of a common ancestor. The second and forth exons of each subgene appeared to be the result of an even earlier duplication event. We propose a model for the evolution of this gene that accounts for the observed patterns of exon size and homology.

Sequence homology between RNAs encoding rat alpha-fetoprotein and rat serum albumin

We have determined the sequences of the recombinant DNA inserts of three bacterial plasmid cDNA clones containing most of the rat alpha a-fetoprotein mRNA. The resultant nucleotide sequence of alpha-fetoprotein was exhaustively compared to the nucleotide sequence of the mRNA encoding rat serum albumin. These two mRNAs have extensive homology (50%) throughout and the same intron locations. The amino acid sequence of rat alpha-fetoprotein has been deduced from the nucleotide sequence, and its comparison to rat serum albumin's amino acid sequence reveals a 34% homology. The regularly spaced positions of the cysteines found in serum albumin are conserved in rat alpha-fetoprotein, indicating that these two proteins may have a similar secondary folding structure. These homologies indicate that alpha-fetoprotein and serum albumin were derived by duplication of a common ancestral gene and constitute a gene family.

Nucleotide sequence of cloned rat serum albumin messenger RNA

The nucleotide sequences of the recombinant DNA inserts of three bacterial plasmid clones containing nearly all of the rat serum albumin mRNA have been determined. A statistical analysis of the nucleotide sequence reveals a pattern of repeated internal homology that confirms the "intragenic triplication" model of albumin evolution.

Hypotensive action of parathyroid hormone preparations on rats and dogs

Bovine parathyroid extract and two commercial preparations containing the first 34 amino acids of synthetic bovine parathyroid hormone [bPTH-(1-34)]produced dose-related hypotension in anesthetized rats. Dogs were 10 times more sensitive to the two bPTH-(1-34) preparations than were rats. Propranolol, phentolamine, atropine, and promethazine did not affect the hypotensive action of bPTH-(1-34) in rats and dogs. bPTH-(1-34) decreased perfusion pressure in rat hindlimbs perfused in situ with Ringer's solution and was a vasodilator in dog kidneys perfused in vitro with Ringer's solution. Helical strips of rabbit aorta were also relaxed by bPTH-(1-34). We conclude that the direct vasodilatory action of bPTH preparations represents an intrinsic property of parathyroid hormone and that the hypotensive effect of this hormone is produced by part or all of the first NH2-terminal 34 amino acids.

Ontogeny of delta activity during human sleep

The study describes the ontogenetic and time-related changes in peak amplitude, frequency, and incidence of delta waves of twenty-five normal subjects between the ages of 3 and 79 years of age. All slow waves greater then 5 muV in magnitude and between 0.5 and 3.0 c/sec were analyzed for the first 6 h of the night's sleep. In this study increasing age was accompanied by decreases in average peak amplitude of delta waves over 5 muV, slowing of delta frequencies, and decreases in incidence of waves greater than 20 muV. Across 2-h epochs of the night there were tendencies for the average peak amplitude of delta waves to decrease, for the average frequency for a given amplitude range to decrease, and for the incidence of low-amplitude delta waves to increase and high-amplitude waves to decrease. The incidence of waves greater than 5 muV remained constant across ages and epochs. Frontal channel delta waves exhibited an age-group difference whereas no such difference was apparent for central channel delta activity, suggesting that the frontal channel may possess advantages over the central because of greater sensitivity to age related changes.

Ecotaxis: the principle and its application to the study of Hodgkin's disease

A study of the function, characterization and distribution of T and B lymphocytes in five children with Hodgkin's disease is presented. The results, indicating that lymphocyte depletion in the peripheral blood does not necessarily reflect an overall lack of circulating lymphocytes, are presented to demonstrate that failure of ecotaxis (normal lymphocyte migration and distribution) can occur in man. The underlying reasons for such failure and their relevance to the pathogenesis of Hodgkin's disease are discussed.

Automated sleep EEG analysis applied to the evaluation of drugs: illustration by study of clorazepate dipotassium

An automated sleep EEG analysis system was used to evaluate the effects of clorazepate dipotassium in normal subjects. Ten young-adult men slept 18 consecutive nights in the laboratory. On days 8-15 clorazepate (7.5 mg) was administered three times daily; on days 5-7 and 16-18 a placebo was administered in a similar fashion. The drug reduced amounts of alpha and delta activity and increased the amount of beta activity and the number of spindles. These effects generally persisted through the 3 day placebo recovery period. Our results suggest that sleep EEG waveform descriptors are sensitive indicators of drug activity and that beta activity in particular may be useful in the detailed description of various drug effects.

Prognostic significance of lymph node histology in patients with squamous cell carcinoma of the larynx, pharynx, or oral cavity

In a double-blind retrospective analysis, sections of lymph nodes regional to head and neck squamous cell carcinomas were microscopically examined to assess morphologically the immunologic pattern of response. Patients whose nodes showed evidence of immunologic stimulation had five-year survival rates significantly higher than those whose nodes showed no evidence of immunologic stimulation. None of the patients whose nodes showed the lymphocyte depletion pattern survived five years. The stage or histologic grade of the tumors did not influence these correlations. Metastases occurred much more frequently in patients whose nodes showed immunologic activity than in those whose did not. The data support the concept that immunologic capacities are important host defense mechanisms against malignancy. Histologic assessment of immunologic activity in regional nodes seems to be an important parameter for predicting survival.