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At least 1,279 records · Page 71Linked to original sources
PubMed1991

Diagnostic peritoneal lavage. Limited indications due to evolving concepts in trauma care.

This study was undertaken to determine the appropriateness of celiotomy in 100 consecutive patients who underwent celiotomy solely because of positive diagnostic peritoneal lavage (DPL) following blunt (B) or stab (S) abdominal trauma. A total of 32 (32%) patients had positive DPL by laboratory criteria: blunt trauma: greater than 100K RBC/mm3, greater than 500 WBC/mm3; stab trauma: greater than 50K RBC/mm3, greater than 250 WBC/mm3. DPL in 68 patients was positive by gross inspection; 18 of these 68 patients' DPL laboratory results returned after surgery and did not satisfy the laboratory definition of positive DPL. In all 61 per cent underwent therapeutic celiotomy (TC) and 39 per cent underwent nontherapeutic celiotomy (NTC). Grade I and II spleen and/or liver injuries led to 79 per cent of NTCs. Positive DPL, determined by gross inspection or by laboratory testing, has a very poor accuracy rate when evaluated in light of evolving beliefs that promote nonoperative therapy for grade I and II liver and spleen injuries. When positive DPL is the sole indication for celiotomy in patients with blunt or stab abdominal trauma, an unacceptably large number of NTCs will be performed. DPL should have a limited role in the evaluation of patients with abdominal trauma.

Abdominal Injuries↗
PubMedDate not supplied

Evolving concepts of the epidemiology, diagnosis, and therapy of Mycobacterium tuberculosis infection.

Tuberculosis in the United States is evolving in nearly all respects--epidemiology, diagnosis, treatment, and prophylaxis. Today a relatively larger segment of the population has predisposing factors to infection with tuberculosis. There is a greater percentage of people who are elderly, who have immigrated from countries endemic for tuberculosis, or who are immunosuppressed due to medications necessary for other conditions, because of malignancies, or because of infection with HIV. Skin test classifications have been revised to give different meanings to different-sized areas of induration at the injection site for defined populations. More sensitive, more specific, and faster diagnostic laboratory tests for tuberculosis are being developed. Short-course chemotherapy of from six to nine months is now accepted as standard treatment, regardless of exactly which of the proven regimens of antibiotics or accepted lengths of therapy is used. Patient compliance is improved with the shorter courses both for treatment and for prophylaxis. Better compliance with therapy results in better treatment outcomes of infections with Mycobacterium tuberculosis.

Antitubercular Agents↗
PubMed1990

Evolving myocardial infarction during percutaneous transluminal coronary angioplasty: the use of portable percutaneous cardiopulmonary support.

Percutaneous transluminal coronary angioplasty (PTCA) has become an invaluable tool in the treatment of coronary artery disease. However, it is not without risks. For the PTCA patient who develops signs and symptoms of an evolving myocardial infarction, the time delay involved in the transportation of the patient from the angiography suite to the operating room becomes important. Institution of cardiopulmonary bypass in the angiography suite has enabled the successful transport of the patient to the operating room in a hemodynamically stable condition. We now present two case reports of patients treated with emergent percutaneous cardiopulmonary bypass following the development of myocardial infarction during PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1990

Isolation of rapidly evolving genomic sequences: construction of a differential library and identification of a human DNA fragment that does not hybridize to chimpanzee DNA.

A differential library enriched in rapidly evolving human genomic sequences was obtained by phenol-enhanced hybridization of human genomic DNA with an excess of chimpanzee DNA. A DNA fragment 110 bp in length that did not hybridize to either chimpanzee or other primate DNA was identified in this library. It was shown to be a substantially diverged member of the human beta satellite family of tandem repeats. The genomic sequences homologous to the fragment were located on the short arms of human acrocentric chromosomes by in situ hybridization. The human-specific fragment failed to hybridize with RNA from different human tissues. The human-specific fragment exhibits a remarkable level of DNA polymorphism in humans and may be used in the identification of human tissue samples, in the selection of human/rodent somatic cell hybrids containing human acrocentric chromosomes, and in the mapping of these chromosomes.

Animals↗
PubMedDate not supplied

Pediatric dentists: evolving demography.

The changing gender, racial and ethnic distribution of enrollees in advanced dental education programs is noted for the period 1983-1988. The evolving demography of pediatric dentistry provides positive role-models and represents an opportunity for better services to American youth.

Dentists, Women↗
PubMed1990

Evolution of oxygen evolving reaction center-II of thylakoids.

A model for evolution of oxygen evolving reaction center II of higher plant initiating from a chlorophyll--quinone complex is proposed. The reaction center gradually incorporates pheophytin, Fe and Mn to finally achieve oxidation of water to oxygen. The structural and functional pattern during evolution is proposed to descend from higher order of symmetry to lower one.

Biological Evolution↗
PubMed1990

[Evolving in prosthetics with the Brånemark system].

The incorporation of the Brånemark root-form osseointegrated implant into the practice of Prosthodontics has opened up a new range of treatment options previously unavailable to our patients. No longer limited to their original use in restoring the completely edentulous arch, the role of implants now includes the replacement of one or more missing teeth in partially edentulous situations. Implants may also be incorporated into periodontal prostheses as supplemental support where the number or strength of existing natural abutments is inadequate, and used as a means of salvaging prostheses which have failed as a result of the loss of strategically important abutments. These newer applications, however, combined with patient demands for the optimum in esthetics as well as function, have served to challenge our ingenuity and resourcefulness in this rapidly evolving field. The objective of this paper is to provide an overview of the evolution of our implant experiences in recent years, and to illustrate the ways in which the Brånemark system has been utilized and adapted as the number and complexity of clinical situations have increased. Simply stated, the technical aspects of prosthetic treatment, those involving impression techniques, materials, etc., have remained fairly constant throughout our implant experience. The more dramatic changes have occurred through the utilization of newer components as they have become available, as well as through a growth in our application of the system and in our approach to treatment planning. The Brånemark system has been in use for just over 25 years at this point in time and has proven itself to be reliable, predictable and at the same time versatile enough to admirably meet the challenges placed on us by the new and varied clinical situations we are now undertaking to treat. It is by using our imaginations to stretch the limits of the system without overstepping its boundaries that we have reached the point where osseointegration is truly becoming a part of our basic armamentarium in the practice of Prosthodontics.

Dental Abutments↗
PubMed1990

Evolving abundance and clonal pattern of human germinal center B cells during childhood.

Childhood is a critical period for the development of the memory B-lymphocyte repertoire necessary in protective humoral immunity. This study addressed the natural history of memory B cells based on the previous identification of germinal center and mantle zone cells as the probable precursor and mature memory cell populations, respectively. Using flow cytometric quantitation of these B-cell subpopulations in human tonsil, we found that germinal center cells were abundant (70% of tonsil B cells) during early childhood (2 to 3 years), but decline by early adolescence (8 to 14 years) to a low level (33%, P = .0003). To study the clonal evolution of these B-cell subpopulations, germinal center and mantle zone B cells were isolated using a preparative magnetic immunobead method, and analyzed using a novel polymerase chain reaction-based quantitative assay to measure the abundance of B-cell clones bearing certain rearranged VH subfamilies. Two VH subfamilies were informative: VH1N clones were uniquely deficient in germinal center B cells at the early age period, but became abundant in later childhood; and VH3L clones were absent among germinal center cells regardless of age. In contrast, B-cell clones bearing each VH subfamily were abundant in the mantle zone subpopulation throughout childhood. These findings suggest that the abundance and clonal pattern of germinal center B cells evolves during childhood, presumably due to changing antigenic or ontogenic processes. Moreover, the distinct clonal pattern of germinal center versus mantle zone B cells suggests that a major phase of clonal selection occurs after germinal center emigration.

Adolescent↗
PubMedDate not supplied

Evolving demographic patterns and potential for pediatric dental practice.

The Bureau of the Census has reported changes in the projected number of children. These changes, as well as the decreases in the number of dentists and a changing awareness of the needed care for children are considered in terms of the potential for pediatric dental practice. Evolving demographic patterns are an important factor in practice location; ten years after the late 1970s, conditions and forecasts now have become far more favorable for the profession.

Adolescent↗
PubMed1989

cDNA sequence, predicted primary structure, and evolving amphiphilic helix of human aspartyl-tRNA synthetase.

Eight of the mammalian aminoacyl-tRNA synthetases associate as a multienzyme complex, whereas prokaryotic and low eukaryotic synthetases occur only as free soluble enzymes. Association of the synthetases may result in effective compartmentalization of synthetases and suggests the association of the entire protein biosynthetic machinery. To elucidate the structural elements and the nature of the molecular interactions involved in the association of the synthetases, we have cloned and sequenced the complementary DNA coding human aspartyl-tRNA synthetase. The full length cDNA encodes an open reading frame of 500 amino acids with 56% identity with yeast aspartyl-tRNA synthetase. The similarity with yeast aspartyl-tRNA synthetase is unevenly distributed with a high percent of identity at the C-terminus and relatively low identity at the N-terminus. The N-terminal sequence strongly prefers an alpha-helical secondary structure and shows amphiphilic characteristics. Further comparison with the yeast synthetases showed that the basic positively charged helixes in yeast synthetases are evolved to a neutral amphiphilic helix in this mammalian synthetase. The mammalian neutral amphiphilic helix is so far unique among all known sequences of bacterial, yeast, and mammalian synthetases and may account for the association of synthetases in the synthetase complex.

Amino Acid Sequence↗
PubMed1989

Transport of proteins into chloroplasts. Import and maturation of precursors to the 33-, 23-, and 16-kDa proteins of the photosynthetic oxygen-evolving complex.

The 33-, 23-, and 16-kDa proteins of the photosynthetic oxygen-evolving complex are synthesized as precursors in the cytoplasm and transported into the thylakoid lumen of higher plant chloroplasts. In this report we have analyzed the import and maturation of these precursors, using reconstituted protein import assays and partially purified preparations of the processing peptidases involved. Precursors of the 33- and 23-kDa proteins from Spinacia and Triticum aestivum are processed by a stromal peptidase to intermediate forms; polypeptides of similar size are observed during the transport of these precursors and possibly that of the 16-kDa protein, into isolated chloroplasts. Complete maturation of the 33- and 23-kDa proteins is carried out by a thylakoidal peptidase shown previously to be involved in plastocyanin biogenesis. The data support an import mechanism involving successive cleavages by the stromal and thylakoidal processing peptidases.

Chlorophyll↗
PubMed1989

The chloroplast reductase-binding protein is identical to the 16.5-kDa polypeptide described as a component of the oxygen-evolving complex.

The N-terminal sequence of the spinach chloroplast reductase-binding protein was determined. The sequence is the same one of a 16.5-kDa polypeptide described as a component of the oxygen-evolving system. Antibodies against both proteins are equivalent as shown by immunoblots, Ouchterlony assays, precipitation of reductase-binding protein complex, and agglutination of thylakoids partially depleted of reductase. These results suggest both proteins are identical. Exposure of the binding protein on the stromal side of thylakoids is supported by agglutination of thylakoids partially depleted of reductase, proteolysis by trypsin, and by accessibility to Fab of anti-binding protein. The latter prevents rebinding of reductase supporting the functional role of the binding protein (16.5 kDa).

Amino Acid Sequence↗
PubMed1989

Aggressive use of intra-aortic balloon pump and emergency coronary bypass surgery. Enhanced survival in acute evolving MI.

This report describes our experience with prophylactic and therapeutic use of IABPs prior to and following coronary artery bypass grafting (CABG) in 39 patients experiencing acute evolving myocardial infarctions (AEMI). All patients showed objective evidence of coronary thrombosis (contrast angiography) followed by later evidence of streptokinase (SK)-induced restoration of antegrade blood flow in the infarct-related coronary artery (as determined by repeat angiography). In these 39 high-risk patients, 38 survived and were discharged. One patient died (2.6 per cent) on the twelfth postoperative day.

Adult↗
PubMed1988

Beta-adrenergic mechanisms during severe myocardial ischemia and evolving infarction.

Severe myocardial ischemia and infarction cause release of catecholamines, with exposure of injured myocardial cells to relatively high concentrations during the transitional period in which myocyte injury worsens. In experimental animals, the number of beta-adrenergic receptors increases markedly without any change in affinity within one hour of coronary artery occlusion, and the number of alpha-adrenergic receptors also increases. Stimulation by exogenous cate-cholamines during a period of reperfusion one hour after temporary coronary occlusion is associated with an enhanced biochemical response in the ischemic myocardium. Administration of beta-adrenergic blockers prior to or within a few minutes after occlusion limits the extent of myocardial necrosis. In clinical studies, administration of propranolol, timolol, or metoprolol has been shown to significantly reduce the mortality rate after myocardial infarction (MI). Administration of timolol or metoprolol also reduces the frequency of recurrent MI. Beta-adrenergic blockers may prolong life and reduce the risk for recurrent MI by antagonizing and/or preventing basic biologic alterations in injured myocytes and/or by antagonizing detrimental effects of the relatively high concentrations of catecholamines to which these cells are exposed. Increased number of beta-adrenergic receptors, the ability to translate adrenergic stimulation into intracellular metabolic events, and increased local concentrations of catecholamines may be important factors in arrhythmogenesis and myocyte injury during severe myocardial ischemia and evolving MI.

Adrenergic beta-Antagonists↗
PubMed1986

Alpha 1 type IV collagen gene evolved differently from fibrillar collagen genes.

Type IV collagen is a major structural component in basement membranes. It is considerably different from the fibrillar collagens, types I-III. For example, unlike fibrillar collagens, the triple helical domain of type IV collagen is frequently interrupted by nonhelical regions. In this report, we demonstrate several overlapping genomic clones which cover most of the mouse alpha 1(IV) chain. Electron microscopic analysis of R-loops revealed that there were at least 28 exons within 35 kilobases of the gene segment. The sizes of six exons were determined by DNA sequence analysis to be 81, 178, 134, 73, 129, and 213 base pairs. These sizes do not appear to be related to the 54-base pair coding unit which is characteristic of fibrillar collagen exons, suggesting that the alpha 1 type IV collagen gene evolved differently from the fibrillar collagen genes.

Actin Cytoskeleton↗
PubMed1986

Safety of helicopter transport and out-of-hospital intravenous fibrinolytic therapy in patients with evolving myocardial infarction.

Of 150 consecutive patients with acute myocardial infarction transported by helicopter for acute intervention, 55 had intravenous thrombolytic therapy (tissue plasminogen activator in 12, streptokinase in 43) initiated prior to transfer. Patients were transported 55 +/- 10 ground miles in 17 +/- 6 minutes and no patient died or experienced bleeding or hemodynamic instability during transfer. Patients receiving thrombolytic therapy had a higher incidence of arrhythmias during transit compared to the untreated group, ventricular tachycardia in six and third-degree atrioventricular block in one compared to ventricular tachycardia in one patient, respectively (p = 0.005). However, these arrhythmias were transient and did not require cardioversion, temporary pacing, or further antiarrhythmic medical treatment. Chest pain was relieved or decreased more frequently in the patients receiving thrombolytic therapy vs. those untreated; 21 of 55 vs. 21 of 95 respectively (p = 0.04). Immediate coronary angiography confirmed a higher incidence and more complete infarct vessel patency (34/55 vs. 30/95) in the patients receiving tissue plasminogen activator or streptokinase (p less than 0.001). Thus, helicopter transfer of patients with evolving myocardial infarction is safe, and early initiation of thrombolytic therapy is associated with increased infarct vessel patency and benign reperfusion arrhythmias.

Aircraft↗
PubMed1988

COOH-terminal processing of polypeptide D1 of the photosystem II reaction center of Scenedesmus obliquus is necessary for the assembly of the oxygen-evolving complex.

Mutant LF-1 of the green alga Scenedesmus obliquus has been described by Metz and co-workers (Metz, J. G., Pakrasi, H., Seibert, M., and Arntzen, C. J. (1986) FEBS Lett. 205, 269-274) to be inactive for light-driven oxygen evolution, despite a functional Photo-system II reaction center. A polypeptide, D1, implicated in the ligation of the primary photoreactants of photosystem II, was shown to migrate with an apparent higher molecular mass on LDS-PAGE in the mutant than in the wild-type (WT) strain. We show here that polypeptide D1 is synthesized in a precursor form in Scenedesmus WT. Following synthesis and insertion into the thylakoid membrane, a 1.5-2-kDa oligopeptide is clipped off with a half-time of 1-2 min, yielding the mature 34-kDa form of the polypeptide. No processing of polypeptide D1 from mutant LF-1 was observed to take place. We show here that polypeptide D1 of LF-1 displays an identical proteolytic fingerprint pattern to the precursor D1 polypeptide of the wild-type strain. These both have molecular masses about 1.5-2 kDa higher than that of the mature WT polypeptide. A polyclonal antibody elicited by a synthetic oligopeptide (14-mer), predicted from the psbA gene nucleotide sequence to be homologous to the COOH terminus of the precursor D1 of spinach, cross-reacts only with D1 of mutant LF-1 and not with mature D1 of spinach, Chlamydomonas, or of Scenedesmus WT. This observation demonstrates that the greater molecular mass of polypeptide D1 from mutant LF-1 and of Scenedesmus WT precursor D1 is derived from a COOH-terminal extension. We conclude that the LF-1 mutant lacks the appropriate nuclear-encoded protease which processes polypeptide D1 at its COOH terminus from the precursor to the mature form. Such processing would appear to be a necessary step toward the stable incorporation of manganese into the oxygen-evolving site.

Amino Acid Sequence↗
PubMed1986

Strategy for treatment of acute evolving myocardial infarction with pulsatile left heart assist device. Can this modality increase survival and enhance myocardial salvage?

This article describes the technique of left heart bypass in the treatment of both experimental and clinical acute myocardial infarction. A new technique of closed-chest percutaneous left heart bypass that can be used in patients with acute evolving myocardial infarction and cardiogenic shock is also described.

Acute Disease↗