Nitric oxide released from activated platelets inhibits platelet recruitment.

Vessel injury and thrombus formation are the cause of most ischemic coronary syndromes and, in this setting, activated platelets stimulate platelet recruitment to the growing thrombus. Recently, a constitutive nitric oxide synthase (NOS) has been identified in human platelets. To further define the capacity of platelets to produce nitric oxide (NO), as well as to study the role of this NO in platelet recruitment, we adapted a NO-selective microelectrode for use in a standard platelet aggregometer, thereby permitting simultaneous measurement of platelet aggregation and NO production. Treatment of platelets with the NO synthase inhibitor -NG-nitroarginine methyl ester (L-NAME), reduced NO production by 92+/-8% in response to 5 microM ADP compared to control but increased aggregation by only 15+/-2%. In contrast, L-NAME had a more pronounced effect on platelet recruitment as evidenced by a 35+/-5% increase in the extent of aggregation, a 33+/-3% decrease in cyclic GMP content, and a 31+/-5% increase in serotonin release from a second recruitable population of platelets added to stimulated platelets at the peak of NO production. To study platelet recruitment accurately, we developed an assay that monitors two platelet populations simultaneously. Nonbiotinylated platelets were incubated with L-NAME or vehicle and activated with ADP. At peak NO production, biotinylated platelets were added. As measured by three-color flow cytometry, there was a 56+/-11% increase in the number of P selectin- positive platelets in the nonbiotinylated population treated with L-NAME as compared to control. When biotinylated platelets were added to the L-NAME-treated nonbiotinylated population, the number of P selectin positive biotinylated plate-lets increased by 180+/-32% as compared to biotinylated platelets added to the control. In summary, stimulated platelets produce NO that modestly inhibits platelet activation but markedly inhibits additional platelet recruitment. These data suggest that platelet-derived NO may regulate platelet recruitment to a growing thrombus.

Bacterial response to eukaryotic cells. Analysis of differentially expressed proteins using nano liquid chromatography-electrospray ionization tandem mass spectrometry.

Host-bacteria interactions have mostly been investigated with regard to the host response or to activities of pathogenic bacteria. In contrast, we aim to identify reactions of non-pathogenic bacteria that result from their contact with host cells of the gastrointestinal tract. In a proteomic approach, the response of non-pathogenic human Escherichia coli bacteria on gut epithelial cells (rat IEC-6) was investigated in an in vitro co-culture model. For this purpose, a sensitive analytical procedure was developed based on the identification of two-dimensional polyacrylamide gel electrophoresis separated proteins by online nanoLC-electrospray ionization MS/MS using a quadrupole time-of-flight tandem mass spectrometer for accurate mass determination. We demonstrate here the efficiency of this technique by the identification of a total of 43 differentially expressed proteins, out of which 25 were up-regulated and 18 were down-regulated. They represent a wide range of molecular weight and different metabolic and physiological functions.

Molecular cloning and nucleotide sequence of the factor IIIlac gene of Lactobacillus casei.

The lactose-specific factor III (FIIIlac of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) was isolated from Lactobacillus casei and purified to homogeneity by conventional protein purification methods. Its apparent native Mr, estimated from steric exclusion chromatography (approx. 39 kDa), and subunit Mr, estimated from sodium dodecyl sulfate-polyacrylamide gels, indicated that it exists as a trimer of identical subunits of 13 kDa. The gene for FIII L. casei lac was cloned into Escherichia coli using the vector pUC18. The coding sequences were contained on an 860-bp BglII-HindIII DNA fragment of the L. casei lactose plasmid, pLZ64. A protein identical in properties to FIII L. casei lac was isolated from clones of E. coli carrying this DNA insert. The nucleotide sequence of the FIII L. casei lac gene was determined by the dideoxy chain-termination technique. The 336-bp open reading frame for FIII L. casei lac was followed by a stem-loop structure, analogous to a Rho-independent terminator. We concluded that the FIII L. casei lac was the terminal gene in what appears to be an operon comprised of the lactose-PTS-P-beta Gal-coding genes. Comparison of the deduced amino acid sequence of FIII L. caseilac with the amino acid sequence of FIII S. aureus lac (derived from peptide sequencing) demonstrated a high degree of homology (49 identical residues and 21 conservative exchanges out of 103 total aa residues). The FIII L. casei lac lacked his82, previously identified as the phosphorylation site of FIII S. aureus. lac His80 was proposed to be the site of histidyl phosphorylation of FIII L. casei lac.

A rational approach to anaesthetic premedication.

Rational use of premedication for anaesthesia must always be modified and updated to keep pace with the evolving fields of anaesthesiology and surgery, as well as to meet changing patient needs and preferences. It is no longer axiomatic that all patients require, and therefore should receive, premedication. Unfortunately, a variety of traditional reasons have been proposed to justify routine premedication in many institutions. Smoothing induction, decreasing reflexes and arrhythmias, decreasing nausea and vomiting, decreasing pain, decreasing secretions, and producing sedation and amnesia have all been claimed historically as beneficial results of premedication. Modern anaesthetic agents and techniques have come a long way towards eliminating the routine need for premedication. In the preoperative period, the goal of an anxiety-free patient who is physiologically uncompromised requires an individualised approach based on experience and an adequate knowledge of current pharmacology. As our knowledge of potential problems associated with anaesthesia has expanded, we have added other classes of drugs such as the H2-histamine receptor blockers and antacids to our premedicant armamentarium. Outpatient and short-stay patients have further challenged our preoperative goal of an anxiety-free patient by requiring individuals to be 'street ready' within a brief period of time after surgery. Even for in-house elective procedures, not every patient is a candidate for routine premedication. A frank preoperative discussion is all that is necessary to effectively allay anxiety in many persons. In these and other special situations, this article will hopefully guide the reader toward a more rational approach to premedicating patients.

Establishing a model to study the regulation of the lactose operon in Lactobacillus casei.

The chromosomally encoded lactose-specific phosphoenol pyruvate-dependent phosphotransferase system (PTS) has been investigated in Lactobacillus casei ATCC 393 [pLZ15-] and it was considered an excellent system to study the regulation of the lactose operon. This chromosomal operon has been cloned and sequenced, being 99% homologous to that encoded on the plasmid pLZ64. Expression of the lactose operon in different mutants of L. casei ATCC 393 [pLZ15-] and primer extension analysis revealed that it is subject to a dual regulation: (i) glucose repression possibly mediated by CcpA and PTS elements, and (ii) induction by lactose through transcriptional antitermination.

Hypoplastic left heart syndrome: a simplified palliative operation.

A simplified, palliative operation for hypoplastic left ventricular syndrome is proposed, its morphologic rationale is documented, and three cases are reported.

Retrograde versus antegrade cardioplegia: impact on right ventricular function.

Retrograde cardioplegia administered through the coronary sinus has several documented advantages over antegrade cardioplegia but has been thought to provide inadequate right ventricular myocardial protection. We prospectively compared the effects of retrograde and antegrade cardioplegia on right ventricular performance in patients undergoing myocardial revascularization. Two groups of similar age, extent of disease, and preoperative left ventricular ejection fraction received retrograde (n = 16) or antegrade (n = 14) crystalloid cardioplegia. A right ventricular rapid-response thermistor catheter, previously developed and validated in our institution, was used to measure right atrial pressure, pulmonary artery pressure, right ventricular ejection fraction, end-diastolic volume index, and stroke volume index before bypass (baseline) and at several intervals after bypass. There were no differences in cross-clamp time, heart rate, cardiac enzymes, inotrope requirements, or arrhythmias between the two groups. Right ventricular parameters were equivalent in both groups at all time intervals except 30 minutes after bypass, at which time right ventricular end-diastolic volume index was lower (80 +/- 6 versus 93 +/- 6 mL/m2; p less than 0.05) and right ventricular stroke volume index was higher (35 +/- 3 versus 29 +/- 2 mL/m2, p less than 0.05) in the retrograde group compared with the antegrade group, indicating better right ventricular function with retrograde cardioplegia early after bypass. In both groups, right ventricular end-diastolic volume index was higher than baseline (p less than 0.05) during the first 4 hours after bypass. No other important differences were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Lithium attenuates hypokinesia induced by immobilization stress in rats.

1. Hypokinesia following immobilization stress in rats is attenuated by anti-depressant drugs used in the treatment of unipolar depression. Lithium has anti-depressant effects both clinically and in other animal models of depression, but the mechanism of its anti-depressant effect has not been elucidated. 2. To determine if lithium reverses immobilization-induced hypokinesia, the effects of lithium and immobilization stress were tested in a fully factorial 2 x 2 design. 3. Half the rats were fed chronic dietary lithium, while the other half ate regular chow. Half of each group were exposed to one hour immobilization, while the other half remained in their home cages until the test. Activity was measured for 20 min in an automated activity meter. 4. Stress significantly reduced activity, but a significant interaction between stress and lithium was found, indicating that lithium attenuated the effect of stress. 5. Lithium-induced attenuation of immobilization stress may serve as an animal model for the anti-depressant effects of lithium.

Central and peripheral minocycline suppresses motor activity in rats.

Minocycline (MIN) HCl is a tetracycline derivative previously shown to inhibit agonist-induced accumulation of cyclic adenosine monophosphate (cAMP) in vitro and suppress motor activity and amphetamine-induced hyperactivity in rats following SC injection. The present study examined the effect of IV and intracerebral MIN on baseline activity and amphetamine-induced hyperactivity. IV MIN suppressed both types of activity in doses of 100 and 150 mg/kg. When injected ICV, MIN (50 micrograms/2 microliter) suppressed the increase in rearing elicited by amphetamine but did not affect baseline activity. MIN did not attenuate the behavioral suppression induced by the cAMP phosphodiesterase inhibitor rolipram. MIN apparently has centrally mediated effects on motor activity in rats; however, it is not yet possible to associate MIN's behavioral effects with its ability to inhibit agonist-induced stimulation of cAMP.

General anesthesia.

The general anesthetic course has been made acceptably safe with the development of modern anesthetic agents and techniques and increased capabilities for monitoring patient organ systems. Each area of surgery has features unique to its specialty. Consideration of these aspects when planning an anesthetic and surgical course, as well as the importance of the team effort, cannot be overemphasized.

The lac operon of Lactobacillus casei contains lacT, a gene coding for a protein of the Bg1G family of transcriptional antiterminators.

The 5' region of the lac operon of Lactobacillus casei has been investigated. An open reading frame of 293 codons, designated lacT, was identified upstream of lacE. The gene product encoded by lacT is related to the family of transcriptional antiterminator proteins, which includes BglG from Escherichia coli, ArbG from Erwinia chrysanthemi, SacT, SacY, and LicT from Bacillus subtilis, and BglR from Lactococcus lactis. Amino acid sequence identities range from 35 to 24%, while similarities range from 56 to 47%. The transcriptional start site of the lac operon was identified upstream of lacT. The corresponding mRNA would contain in the 5' region a sequence with high similarity to the consensus RNA binding site of transcriptional antiterminators overlapping a sequence capable of folding into a structure that resembles a rho-independent terminator. LacT was shown to be active as an antiterminator in a B. subtilis test system using the sacB target sequence. lacT directly precedes lacEGF, the genes coding for enzyme IICB, phospho-beta-galactosidase, and enzyme IIA, and these genes are followed by a sequence that appears to encode a second rho-independent transcription terminator-like structure. Northern hybridizations with probes against lacT, lacE, and lacF revealed transcripts of similar sizes for the lac mRNAs of several L. casei strains. Since the length of the lac mRNA is just sufficient to contain lacTEGF, we conclude that the lac operon of L. casei does not contain the genes of the accessory tagatose-6-phosphate pathway as occurs in the lac operons of Lactococcus lactis, Streptococcus mutans, or Staphylococcus aureus.

The gal genes for the Leloir pathway of Lactobacillus casei 64H.

The gal genes from the chromosome of Lactobacillus casei 64H were cloned by complementation of the galK2 mutation of Escherichia coli HB101. The pUC19 derivative pKBL1 in one complementation-positive clone contained a 5.8-kb DNA HindIII fragment. Detailed studies with other E. coli K-12 strains indicated that plasmid pKBL1 contains the genes coding for a galactokinase (GalK), a galactose 1-phosphate-uridyltransferase (GalT), and a UDP-galactose 4-epimerase (GalE). In vitro assays demonstrated that the three enzymatic activities are expressed from pKBL1. Sequence analysis revealed that pKBL1 contained two additional genes, one coding for a repressor protein of the LacI-GalR-family and the other coding for an aldose 1-epimerase (mutarotase). The gene order of the L. casei gal operon is galKETRM. Because parts of the gene for the mutarotase as well as the promoter region upstream of galK were not cloned on pKBL1, the regions flanking the HindIII fragment of pKBL1 were amplified by inverse PCR. Northern blot analysis showed that the gal genes constitute an operon that is transcribed from two promoters. The galKp promoter is inducible by galactose in the medium, while galEp constitutes a semiconstitutive promoter located in galK.

Molecular cloning and DNA sequence of lacE, the gene encoding the lactose-specific enzyme II of the phosphotransferase system of Lactobacillus casei. Evidence that a cysteine residue is essential for sugar phosphorylation.

The gene coding for the lactose-specific Enzyme II of the Lactobacillus casei phosphoenolpyruvate-dependent phosphotransferase system, lacE, has been isolated by molecular cloning and expressed in Escherichia coli. The DNA sequence of the lacE gene and the deduced amino acid sequence are presented. The putative translation product comprises a hydrophobic protein of 577 amino acids with a calculated molecular mass of 62,350 Da. The deduced polypeptide has a high degree of sequence similarity with the corresponding lactose-specific enzymes II of Staphylococcus aureus and Lactococcus lactis. The sequence surrounding cysteine 483 was strongly conserved in the three proteins. The identity of the lacE product as the Enzyme IIlacL.casei was demonstrated by in vitro lactose phosphorylation assays using the protein expressed in E. coli. Single replacement of each of the histidine and cysteine residues by site-directed mutagenesis pointed to cysteine 483 as an amino acid residue essential for the phosphoryl group transfer reaction.

Bacterial phosphoenolpyruvate-dependent phosphotransferase system: P-Ser-HPr and its possible regulatory function?

HPr of the bacterial phosphotransferase system is a histidine-containing phospho-carrier protein. It is phosphorylated at a single histidyl residue with phosphoenolpyruvate (PEP) and enzyme I and transfers the histidyl-bound phosphoryl group to a variety of factor III proteins. Recently, we described an HPr phosphorylated at a seryl residue (P-Ser-HPr), which is formed in an adenosine 5'-triphosphate dependent reaction catalyzed by a protein kinase [Deutscher, J., & Saier, M.-H., Jr. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 6790-6794]. Now we demonstrate that this P-Ser-HPr is an altered substrate of phosphorylated enzyme I and factor III proteins compared to unphosphorylated HPr. Thus, P-Ser-HPr of Streptococcus lactis is phosphorylated about 5000 times slower by PEP and enzyme I than HPr. The slow phosphorylation by PEP and enzyme I can be overcome when factor III protein specific for gluconate (factor III(Gct)) of Streptococcus faecalis is added. Most likely, a complex of P-Ser-HPr and factor III(Gct) is formed which then becomes phosphorylated as fast as free HPr. Factor III protein specific for lactose (factor III(Lac)) of Staphylococcus aureus also enhances the phosphorylation of P-Ser-HPr by enzyme I and PEP, but its effect is lower. Thus, P-Ser-HPr is phosphorylated 70-100-fold slower in the presence of factor III(Lac) than in the presence of factor III(Gct). The described interaction of P-Ser-HPr with enzyme I in the presence of different factor III proteins could account for the regulation of sugar uptake within the phosphotransferase system. Some of the phosphoenolpyruvate-dependent phosphotransferase system sugars like glucose are known to be taken up in preference to others, for example, lactose.

Detection of S-nitrosothiols and other nitric oxide derivatives by photolysis-chemiluminescence spectrometry.

We have developed a method for the detection of biologically relevant derivatives of NO. that couples photolysis to chemiluminescence. S-Nitrosothiols, N-nitroso-L-tryptophan, and iron-nitrosyl derivatives can all be detected by this methodology, and these derivatives can be distinguished from free NO. by making measurements with and without photolysis. The limits of detection of this system are in the 10 nM range, with an intraassay variability of less than 2% and an interassay variability of less than 1.5%. The use of cutoff filters and alterations in pH and flow rate through the photolysis cell provide additional useful parameters with which to characterize specific NO. derivatives based on their intrinsic stability. This methodology is a useful addition to the growing armamentarium of techniques used to characterize the biochemistry and metabolism of NO..

An exploratory study of the interaction between language teaching methods and child characteristics.

The present study examined whether the relative efficacy of two language teaching methods was predicted by pretreatment subject characteristics. Forty handicapped preschoolers were randomly assigned to two language teaching methods (i.e., Milieu Teaching and the Communication Training Program). No main effects of treatment were found. However, seven statistical interactions between pretreatment subject characteristics and language teaching method indicated that lower-functioning children benefitted more from the Milieu method and higher-functioning children benefitted more from the Communication Training Program. The results were discussed in relation to the extant literature reporting subject-by-language-teaching-method interactions. The importance of replicating the present results and specific suggestions for subject selection criteria and pretreatment subject characteristics likely to interact with language teaching methods similar to those used in this study are discussed.