Enthalpic and entropic determinants for the specificity of alkylation of the histidine-12 residue of ribonuclease A by four bromoacetamido nucleoside affinity labels and bromoacetamide.

The binding and alkylation rate constants for the reaction of four bromoacetamido pyrimidine nucleosides and bromoacetamide with bovine pancreatic ribonuclease A (RNase A) have been determined as a function of temperature. The four nucleoside derivatives react exclusively or preferentially with the NE2 atom of histidine-12 and include 2'-bromoacetamido-2'-deoxyuridine, 2'-bromoacetamido-2'deoxyxylofuranosyluracil, 3'-bromoacetamido-3'-deoxythymidine and 3'-bromoacetamido-3'-deoxyarabinofuranosyluracil. Transition-state parameters, delta H++ and delta S++, reveal that nucleosides with "up" OH groups experience relative rate enhancements which have been attributed to contacts between these groups and the enzyme in the transition state (1).

Kinetics of the lamellar and hexagonal phase transitions in phosphatidylethanolamine. Time-resolved x-ray diffraction study using a microwave-induced temperature jump.

The kinetics of the thermotropic lamellar gel (L beta')/lamellar liquid crystal (L alpha) and L alpha/inverted hexagonal (HII) phase transitions in fully hydrated dihexadecylphosphatidylethanolamine (DHPE) have been studied. Measurements were made by using time-resolved x-ray diffraction (TRXRD) to monitor progress of the transitions. In these studies microwave energy at 2.

Familial hypercholesterolemia in a rhesus monkey pedigree: molecular basis of low density lipoprotein receptor deficiency.

We have recently identified a family of rhesus monkeys with members exhibiting a spontaneous hypercholesterolemia associated with a low density lipoprotein receptor (LDLR) deficiency. By using the polymerase chain reaction, we now show that the affected monkeys are heterozygous for a nonsense mutation in exon 6 of the LDLR gene. This mutation changes the sequence of the codon for amino acid 284 (tryptophan) from TGG to TAG, thereby generating a nonsense codon potentially resulting in a truncated 283-amino acid protein, which needs documentation, however.

Effect of sepsis on amino acid transport system A and its response to insulin in incubated rat skeletal muscle.

The effect of sepsis on neutral amino acid transport systems A, ASC, and L, was studied in incubated rat soleus (SOL) muscles. We also examined the effects of plasma from septic rats and of varying concentrations of insulin (10 to 10(5) microU/mL), added in vitro to incubated muscles, on system A amino acid transport. Sepsis was induced by cecal ligation and puncture (CLP) in rats weighing 40 to 60 g.

Effect of catabolic hormone infusion on protein turnover and amino acid uptake in skeletal muscle.

Increased plasma levels of the catabolic hormones glucagon, epinephrine, and cortisol have been implicated in mediating various metabolic alterations in trauma and sepsis. Their role in altered protein turnover and amino acid transport in skeletal muscle during sepsis, however, is not known. In the current study, rats were infused with a mixture of the catabolic hormones for 16 hours.

Reduced amino acid transport in skeletal muscle caused by a circulating factor during endotoxemia.

The present study was designed to determine whether reduced amino acid uptake in skeletal muscle during endotoxemia is due to associated hypotension or is caused by a factor present in plasma. Three series of experiments were performed. In the first series of experiments, mean arterial pressure (MAP), heart rate, and amino acid uptake in incubated soleus muscles were measured after intravenous injection of endotoxin (1 mg/kg) in male Sprague-Dawley rats (40 to 60 g).

Causality and the allocation of attention during comprehension.

Recent research has suggested that each statement in a narrative text is understood by relating it to its causal antecedents and consequences and that the text as a whole is understood by finding a causal path linking its opening to its final outcome. Fletcher and Bloom (1988) have proposed that in order to accomplish this goal, while minimizing the number of times long-term memory has to be searched, readers focus their attention on the last clause of a narrative that has causal antecedents but no consequences in the preceding text. As a result, a statement that is followed by a causal antecedent should remain the focus of attention, while the same statement followed by a consequence should not.

Suppression of LH-stimulated prostaglandin and progesterone accumulation in rat granulosa cells by isoquinolinesulfonamide protein kinase inhibitors.

Rat granulosa cells were incubated with isoquinolinesulfonamide inhibitors of protein kinases A and C and/or LH, dibutyryl cAMP (dbcAMP), tetradecanoylphorbol acetate (TPA), cholera toxin, or forskolin for 5 h. H7 (25 microM) was observed to inhibit LH, cholera toxin or dbcAMP stimulation of prostaglandin (PGE), and progesterone accumulation. H7 produced inhibition when added as little as 2 min before and as long as 1 h after LH.

Inhibited amino acid uptake in skeletal muscle during starvation.

Amino acid uptake in skeletal muscle is reduced during different catabolic conditions such as sepsis, endotoxic shock, and uremia. The present study was designed to determine the effect of another catabolic condition, starvation, on amino acid transport in skeletal muscle. Male Sprague-Dawley rats (40-60 g) were starved for 24, 48, or 72 hr and soleus (SOL) muscles were removed intact and incubated for 2 hr in a medium consisting of Krebs-Henseleit bicarbonate buffer (pH 7.

Long-acting somatostatin analog controls acid and gastrin secretion in benign, not in malignant, Zollinger-Ellison syndrome.

The long-acting somatostatin (SMS) analog, SMS 201-995 has beneficial effects on APUDomas. In two Zollinger-Ellison syndrome (ZES) patients we assessed basal acid output (BAO) and 24-h pH under SMS and compared them to controls. We also assessed total gastrin, gastrin 17, insulin, glucagon, C-peptide, and SMS by radioimmunoassay.

The effect of sepsis in rats on skeletal muscle protein synthesis in vivo and in periphery and central core of incubated muscle preparations in vitro.

Recent studies demonstrated the development of a central, hypoxic core in incubated rat skeletal muscles. The influence of a central core on changes in protein synthesis rate, observed in incubated muscles from septic rats, is not known. In the present study, intact soleus muscles from 40 to 60-g sham-operated control rats and from septic rats (16 hours after cecal ligation and puncture) were incubated in vitro in a flaccid or stretched state.

Effects of indomethacin and leupeptin on muscle cathepsin B activity and protein degradation during sepsis.

The roles of prostaglandins and lysosomal proteases in accelerated skeletal muscle proteolysis during sepsis are not yet fully understood. In this study rats received intraperitoneal injections of the prostaglandin synthesis inhibitor indomethacin (IND, 5.0 mg/kg), the lysosomal cathepsin B inhibitor leupeptin (LEU, 2.

Nucleotide sequence of a cDNA for branched chain acyltransferase with analysis of the deduced protein structure.

Nucleotide sequence was determined for a 1.6-kilobase human cDNA putative for the branched chain acyltransferase protein of the branched chain alpha-ketoacid dehydrogenase complex. Translation of the sequence reveals an open reading frame encoding a 315-amino acid protein of molecular weight 35,759 followed by 560 bases of 3'-untranslated sequence.

Further evidence that accelerated muscle protein breakdown during sepsis is not mediated by prostaglandin E2.

Prostaglandin E2 (PGE2) reportedly increases protein break-down in skeletal muscle. The role of PGE2 for accelerated muscle proteolysis during sepsis, however, is controversial. In this study, the effect of the prostaglandin synthesis inhibitor indomethacin on PGE2 release and protein breakdown in skeletal muscle from nonseptic and septic rats was evaluated.

Quantification of low numbers of immunogold label on Lowicryl K4M sections.

Postembedding immunogold staining was used to quantify low numbers of intracytoplasmic cytokine interferon molecules in cells embedded in Lowicryl K4M by the rapid technique of Altman et al. (1984). When labelling with colloidal gold-protein A (CGPA) was performed as suggested by the manufacturers, the relatively high background precluded the statistically significant distinction of small amounts of specific label.

Thiostrepton resistance mutations in the gene for 23S ribosomal RNA of halobacteria.

Mutants of Halobacterium (H.) halobium and H. cutirubrum were isolated which are resistant to the 70S ribosome inhibitor thiostrepton.

Switch region content of hybridomas: the two spleen cell Igh loci tend to rearrange to the same isotype.

We have examined the switch region content of 25 hybridomas that secret antibodies of various isotypes with specificity for phosphocholine or glycoproteins of herpes simplex virus. These Southern hybridization experiments included probes for the murine JH region as well as probes for the mu, gamma 3, gamma 1, gamma 2b, gamma 2a, and alpha switch regions. For 22 of the hybridomas, the deletion model of the heavy chain switch fits the data well--all switch regions upstream of the rearranged (and expressed) switch regions are deleted and all switch regions downstream remain in the germline configuration.

A prospective study of thymopentin in severely burned patients.

A randomized prospective double-blind study of thymopentin was performed upon 24 severely burned patients to evaluate its efficacy in correcting postburn immunologic abnormalities and preventing infectious morbidity and mortality. Patients in the treated group received 50 milligrams of thymopentin daily for the first two weeks after injury and three times weekly thereafter until the patient was no longer at risk for having infections develop. The placebo group received saline solution intravenously.

23S ribosomal RNA mutations in halobacteria conferring resistance to the anti-80S ribosome targeted antibiotic anisomycin.

Halobacterium (H.) halobium and H. cutirubrum mutants resistant to the anti-80S ribosome targeted inhibitor anisomycin were isolated.

The immunoglobulin heavy chain switch: structural features of gamma 1 recombinant switch regions.

The immunoglobulin heavy chain isotype switch is mediated by a DNA rearrangement involving specific genomic segments referred to as switch regions. Switch regions are composed of tandemly repeated simple sequences. The role of the tandemly repeated structure of switch regions in the switch recombination process is not understood.

Nucleotide sequences of mRNAs encoding Epstein-Barr virus nuclear proteins: a probable transcriptional initiation site.

Three cDNA clones of the second Epstein-Barr virus nuclear antigen (EBNA2) mRNA and two of the EBNA1 mRNA were analyzed. Two EBNA2 clones begin 42 bases 3' to a promoter in the Epstein-Barr virus long internal repeat, which is likely to be the EBNA2 promoter. Surprisingly, the first splice creates an AUG at the beginning of the first of two nonoverlapping open reading frames.

Preterm labor associated with subclinical amniotic fluid infection and with bacterial vaginosis.

Maternal genital infection, particularly subclinical amniotic fluid infection, may cause preterm labor and a premature delivery. The prevalence of subclinical amniotic fluid infection was studied in 54 consecutive afebrile women in preterm labor with singleton gestations and intact fetal membranes. Microorganisms were recovered from the amniotic fluid by transabdominal amniocentesis in 13 (24%) of 54 patients.

Herpes simplex virus expressing Epstein-Barr virus nuclear antigen 1.

DNA fragments containing an open reading frame known to encode most or all of the EBNA1 protein of Epstein-Barr virus (EBV) were fused in the proper transcriptional orientation to the promoter regulatory domain, capping site, and a portion of the 5' transcribed noncoding sequences of the HSV-1 alpha 4 gene of herpes simplex virus 1 (HSV-1). In these constructs 20, 130, or 385 bp of EBV DNA and 28 bp of HSV-1 DNA separated the alpha 4 cap site from a putative initiator codon of the EBNA1 gene. The chimeric alpha 4-EBNA1 genes were introduced into L cells or recombined into the viral genome using the thymidine kinase selection system.

Receptive fields and the representation of visual information.

Receptive fields in the retina indicate the first measurements taken over the (discrete) visual image. Why are they circular surround with an excitatory/inhibitory structure? We hypothesize that this provides a representation of the visual information in a form suitable for transmission over the optic nerve, a rather limited channel, that can then be extended into a variety of representations at the cortex. These cortical representations span a range of sizes and functionally separate positive and negative contrast data, precisely as is required for further processing.

Recurrent and persistent vulvovaginal candidiasis: treatment with ketoconazole.

Forty-two women were administered ketoconazole, an orally absorbed antifungal agent. The symptoms of vulvar pruritus, burning, pain, and dysuria and the signs of vulvar erythema and fissures and vaginal erythema were associated with Candida albicans. Although ketoconazole relieved symptoms and signs seven days after therapy, a high recurrence rate occurred by 28 days after therapy.