Resistance to fever induction and impaired acute-phase response in interleukin-1 beta-deficient mice

We used gene targeting in embryonic stem cells to introduce an IL-1 beta null allele in mice. The IL-1 beta-deficient mice develop normally and are apparently healthy and fertile. The IL-1 beta null mice responded normally in models of contact and delayed-type hypersensitivity or following bacterial endotoxin LPS-induced inflammation. The IL-1 beta-deficient mice showed equivalent resistance to Listeria monocytogenes compared with wild-type controls. In contrast, when challenged with turpentine, which causes localized inflammation and tissue injury, the IL-1 beta mutant mice exhibited an impaired acute-phase inflammatory response and were completely resistant to fever development and anorexia. These results highlight a central role for IL-1 beta as a pyrogen and a mediator of the acute-phase response in a subset of inflammatory disease models, and support the notion that blocking the action of a single key cytokine can alter the course of specific immune and inflammatory responses.

Abscisic Acid Structure-Activity Relationships in Barley Aleurone Layers and Protoplasts (Biological Activity of Optically Active, Oxygenated Abscisic Acid Analogs)

Optically active forms of abscisic acid (ABA) and their oxygenated metabolites were tested for their biological activity by examining the effects of the compounds on the reversal of gibberellic acid-induced [alpha]-amylase activity in barley (Hordeum vulgare cv Himalaya) aleurone layers and the induction of gene expression in barley aleurone protoplasts transformed with a chimeric construct containing the promoter region of an albumin storage protein gene. Promotion of the albumin storage protein gene response had a more strict stereochemical requirement for elicitation of an ABA response than inhibition of [alpha]-amylase gene expression. The naturally occurring stereoisomer of ABA and its metabolites were more effective at eliciting an ABA-like response. ABA showed the highest activity, followed by 7[prime]-hydroxyABA, with phaseic acid being the least active. Racemic 8[prime]-hydroxy-2[prime],3[prime]-dihydroABA, an analog of 8[prime]-hydroxyABA, was inactive, whereas racemic 2[prime],3[prime]-dihydroABA was as effective as ABA. The differences in response of the same tissue to the ABA enantiomers lead us to conclude that there exists more than one type of ABA receptor and/or multiple signal transduction pathways in barley aleurone tissue.

Perspectives for the control of tuberculosis

The control of tuberculosis has become more elusive with the increased incidence of HIV, and the continued selection of multidrug-resistant organisms. The intracellular pathogenesis of, and host-response to Mycobacterium tuberculosis present challenges to both classical chemotherapeutic and vaccination approaches, with the organism able to replicate in an unrestricted manner in lung but not other tissues. Adequate control of this pathogen, that has evolved so successfully for its symbiotic exploitation of man, will require complex approaches including additional chemotherapeutics of more acceptable toxicity and efficacy, vaccination and commitment to public health measures. In this review, the worldwide scope of the disease is outlined, and its direct and indirect costs considered. The organism enjoys the protective advantages of a slow replication and of a specialized phagolysosomal intracellular niche, requiring a host-response capable of breaching these cellular barriers. The challenges of current vaccine approaches, including live vaccines, target antigen selection and the antigen delivery and adjuventation necessary to elicit adequate pulmonary responses are discussed. Our current understanding is inadequate to control TB and the rekindling of fundamental experimental approaches to the organism, and the host response it evokes, are essential to generate the preventative and therapeutic means necessary for its worldwide control.

A combined hospital experience with fundoplication and gastric emptying procedure for gastroesophageal reflux in children

BACKGROUND

Operative treatment of symptomatic gastroesophageal reflux (GER), often together with neurologic feeding disorders, is very common in infancy and childhood. Delayed gastric emptying (DGE) has been observed frequently in association with GER in children.

STUDY DESIGN

A retrospective review was performed on 1,200 consecutive patients 18 years of age and younger operated upon for symptomatic GER or neurologic feeding disorders, or both, at two pediatric surgery centers in widely separated geographic areas in the United States of America, to compare the results after fundoplication with or without a gastric emptying procedure (GEP).

RESULTS

Operations included gastroesophageal fundoplication (GEF) alone (871 patients), GEF plus GEP (286 patients), reoperative GEF plus GEP (30 patients), and GEP alone (13 patients). Thus, 27 percent of the total and 40 percent of the last 494 children with reflux had a GEP. Delayed gastric emptying with retention of more than 60 percent of an isotope meal appropriate for age at 90 minutes was present in 241 of the 451 children with reflux studied. Major neurologic disorders were present in 219 (25 percent) of 871 children who underwent GEF alone and in 247 (75 percent) of 329 children who had a GEP. All patients operated upon from both hospitals were relieved of recurrent emesis, and those with failure to thrive showed significant weight gain; pulmonary symptoms were relieved in 94 percent. Recurrent GER developed in 47 (5.2 percent) of 901 children who had GEF alone, but in only four (1.2 percent) of 329 patients who had a GEP.

CONCLUSIONS

The excellent clinical results with low morbidity in this largest reported clinical experience with GEP in childhood suggest that a GEP should be combined with GEF for symptomatic children who have both GER and DGE. Minimal investigative studies are necessary for most neurologically impaired children who require a feeding gastrostomy.

The early management of large burns

The first article in this series (Vol 52 (11), p.583) discussed the pathophysiological processes involved in burn injury. This article describes the early management of large burns, in which treatment is considered in four stages: resuscitation, assessment, further care and transfer. The mnemonic 'RAFT' is suggested as a means of assisting recall of the management process.

Postoperative neuroleptic malignant syndrome

This report describes neuroleptic malignant syndrome in a previously healthy 6-year-old child. Droperidol and metoclopramide had been given, and hyponatraemia may have been a precipitating factor. Treatment with dantrolene sodium combined with a forced alkaline diuresis resulted in a full recovery.

The value of incorporating avoidable factors into perinatal audits

OBJECTIVE

To assess whether incorporating a system of identifying, classifying and grading avoidable factors into a perinatal audit can be useful in identifying problem areas.

DESIGN

Descriptive study.

SETTING

Black urban population, Pretoria, South Africa.

SUBJECTS

All perinatal deaths of infants weighing more than 1,000 g from urban areas served by Kalafong Hospital between August 1991 and July 1992.

METHODS

All perinatal deaths were classified according to the primary obstetric cause of death and neonatal cause of death, and whether any avoidable factors were present which could have contributed to the death.

RESULTS

The perinatal mortality rate was 26/1,000 deliveries. Avoidable factors occurred in 58% of perinatal deaths. Our problem areas which were immediately remedial were identified as labour management-related problems, administrative problems in obtaining syphilis results, and estimation of fetal weight. Other problem areas which need to be solved are patient education, early attendance at clinics, improved documentation and continuing education of medical personnel.

CONCLUSION

The use of this classification of avoidable factors has enabled the detection of problem areas that can be improved immediately at very little cost.

Pathophysiological basis of burn management

Despite increased public awareness of the dangers of fire, burns remain a part of everyday life. Most accident departments will see one or more burn victims each day and, although not common, major burns still occur. In this and a second article we review the pathophysiology of thermal injury and describe the early treatment of a major burn victim.

Caring for gravely ill children

BACKGROUND

Much has been written about the care of the hopelessly ill adult, but there is little guidance for pediatric health care professionals in the management of children who are critically or terminally ill.

METHODS

Through a 3-day meeting in Tarrytown, NY, attended by a group of pediatricians and others directly involved in these issues, a principled approach was developed for the treatment of, and health care decision-making for, children who are gravely ill.

RESULTS

The group agreed that the needs and interests of the child must be the central focus of any treatment plan and that the child should be involved to as great extent possible, consistent with developmental maturity, in the decision-making process. Quality of future life should be viewed as being relevant in all decisions. Parents are believed to be the natural guardians of children and ought to have great latitude in making decisions for them. However, parental discretion is not absolute and professionals must maintain an independent obligation to protect the child's interests.

CONCLUSIONS

Decision-making should be collaborative among patient, parents, and professionals. When conflict arises, consultation and ethics committees may assist in resolution. When cure or restoration of function is no longer possible, or reasonable, promotion of comfort becomes the primary goal of management. Optimal use of pain medication and compassionate concern for the physical, psychological, and spiritual well-being of the child and family should be the primary focus of the professionals caring for the dying child.

p59fyn tyrosine kinase regulates p56lck tyrosine kinase activity and early TCR-mediated signaling

To study the role of p59fyn in T cell activation, we used antisense RNA to inhibit p59fyn expression in a T cell clone. Transfectants with reduced levels of p59fyn were functionally impaired in their responses to antigen, Con A+recombinant IL-1 and cross-linking with anti-TCR mAb. Induction of tyrosine phosphorylation on most intracellular substrates was greatly reduced. We also noted that the lck kinase activity was greatly reduced even though the amount of lck protein was equivalent to that present in parental D10 cells. Our results suggest that the protein tyrosine kinase p59fyn is critical in TCR-mediated signaling and also suggests that p59fyn may regulate p56lck tyrosine kinase activity.

An unwanted inheritance? Family studies into the genetics of asthma

1. Atopy underlies allergic asthma, rhinitis and eczema. 2. Atopy can be defined as a general state of excessive IgE responsiveness. 3. The aim of these genetic studies is the development of more effective preventions and treatments for asthma and other atopic disorders.

Achieving dietary recommendations: whole-grain foods in the Food Guide Pyramid

The Food Guide Pyramid illustrates USDA's food guide developed to help people follow the Dietary Guidelines for Americans. Unlike earlier food guides, the new food guide specifies foods for a total diet; that is, it addresses both concerns about adequacy and moderation. The food guide recommends increased intakes of the vegetable, fruit, and grain groups with special emphasis on dark-green leafy vegetables, legumes, and whole-grain products. These foods are important sources of several vitamins and minerals, complex carbohydrates, and dietary fiber, and they are generally low in fat. Analyses of expected nutrient levels provided by the food guide diet patterns indicate that the nutrient contribution of whole-grain products is particularly important for diets at lower calorie levels. In these diets, it is recommended that at least half the number of servings in the grain group be whole-grain products. In all diets, it is recommended that several servings of whole-grain products be included each day. Average intakes of vegetables, fruits, and grain products are less than recommended. The pyramid graphic has been especially helpful in emphasizing to the public the importance of increased consumption of vegetables, fruits, and grain products for a healthful diet.

Diffraction quality crystals of protein X from Azotobacter vinelandii

Protein X from Azotobacter vinelandii has recently been shown to be either a NADPH oxidase or a NADP+ reductase that interacts specifically with ferredoxin I. Single crystals have been obtained by vapor diffusion from polyethylene glycol 4000 solutions containing 100 mM citrate buffer (pH 5.5). The crystals belong to space group P2(1)2(1)2 with unit cell constants a = 68.9 A, b = 76.9 A, c = 52.8 A and one molecule (M(r) 29,000) per asymmetric unit. The crystals diffract to 2.5 A resolution.

2.2 A structure of oxy-peroxidase as a model for the transient enzyme: peroxide complex

The Fe+3-OOH complex of peroxidases has a very short half life, and its structure cannot be determined by conventional methods. The Fe+2-O2 complex provides a useful structural model for this intermediate, as it differs by only one electron and one proton from the transient Fe+3-OOH complex. We therefore determined the crystal structure of the Fe+2-O2 complex formed by a yeast cytochrome c peroxidase mutant with Trp 191 replaced by Phe. The refined structure shows that dioxygen can form a hydrogen bond with the conserved distal His residue, but not with the conserved distal Arg residue. When the transient Fe+3-OOH complex is modelled in a similar orientation, the active site of peroxidase appears to be optimized for catalysing proton transfer between the vicinal oxygen atoms of the peroxy-anion.

Nuclear localization of the PEP protein tyrosine phosphatase

PEP is an intracellular protein tyrosine phosphatase expressed primarily by cells of hematopoietic origin that can be divided structurally into a catalytic domain and a large carboxy-terminal domain. The carboxy-terminal domain is enriched in proline, glutamic acid, serine, and threonine residues (PEST sequences) and contains a nonperfect tandem repeat sequence enriched in proline residues and a carboxy terminus enriched in basic amino acids. Here we show that PEP is diffusely expressed in lymphoid tissues, consistent with expression by many different cell types. Analysis of the PEP protein identifies a nuclear localization sequence within the extreme carboxy terminus. Transfer of 18 amino acids from the carboxy terminus of PEP to beta-galactosidase conferred nuclear localization, indicating that this sequence was sufficient for nuclear localization. Proteins enriched in PEST sequences are often rapidly degraded. However, pulse-chase analysis indicates that PEP has a half-life of greater than 5 h.

Patients' experiences of emergency admission: how relevant is the British government's Patients Charter?

This paper evaluates the British government's Patients Charter from the perspective of patients admitted via accident and emergency departments. It uses qualitative data obtained about issues of concern to these patients to judge whether the standards set out in the Charter are appropriate to their priorities and, conversely, if there are issues of importance to these patients which the Charter overlooks. Semi-structured interviews were conducted with 83 patients admitted to two London hospitals. It is concluded that the rights and standards outlined in the Patients Charter are generally appropriate to these patients' experiences, although some are defined too narrowly. The study identified a number of issues of importance to patients which are not mentioned in the Patients Charter: pain relief, giving information, receiving information, reception staff, examinations and investigations, physical environment, and other people in casualty. The patient wants rather more than recent British government documents suggest.

The crystal structure of lysin, a fertilization protein

Lysin, a protein from abalone sperm, creates a hole in the envelope of the egg, permitting the sperm to pass through the envelope and fuse with the egg. The structure of lysin, refined at 1.9 angstroms resolution, reveals an alpha-helical, amphipathic molecule. The surface of the protein exhibits three features: two tracks of basic residues that span the length of the molecule, a solvent-exposed cluster of aromatic and aliphatic amino acids, and an extended amino-terminal hypervariable domain that is species-specific. The structure suggests possible mechanisms of action.

Survey of the distribution of a newly characterized receptor for advanced glycation end products in tissues

Advanced glycation end products (AGEs), the final products of nonenzymatic glycation and oxidation of proteins, are found in the plasma and accumulate in the tissues during aging and at an accelerated rate in diabetes. A novel integral membrane protein, termed receptor for AGE (RAGE), forms a central part of the cell surface binding site for AGEs. Using monospecific, polyclonal antibody raised to human recombinant and bovine RAGE, immunostaining of bovine tissues showed RAGE in the vasculature, endothelium, and smooth muscle cells and in mononuclear cells in the tissues. Consistent with these data, RAGE antigen and mRNA were identified in cultured bovine endothelium, vascular smooth muscle, and monocyte-derived macrophages. RAGE antigen was also visualized in bovine cardiac myocytes as well as in cultures of neonatal rat cardiac myocytes and in neural tissue where motor neurons, peripheral nerves, and a population of cortical neurons were positive. In situ hybridization confirmed the presence of RAGE mRNA in the tissues, and studies with rat PC12 pheochromocytes indicated that they provide a neuronal-related cell culture model for examining RAGE expression. Pathological studies of human atherosclerotic plaques showed infiltration of RAGE-expressing cells in the expanded intima. These results indicate that RAGE is present in multiple tissues and suggest the potential relevance of AGE-RAGE interactions for modulating properties of the vasculature as well as neural and cardiac function, prominent areas of involvement in diabetes and in the normal aging process.

Stereoselective blockade of amphibian epithelial sodium channels by amiloride analogs

The blockade of amphibian epithelial sodium channels by amiloride has been shown to not be a simple diffusion-limited encounter but rather a selective binding process with the rate of approach of the molecule for the channel site determined by the side chain at position 2 of the pyrazine ring and the stability of the blocking complex provided largely by the bond of the ligand at position 6. The presence of such a putative channel-associated receptor suggests that the sodium channel might have chiral recognition for its blockers. Using the short-circuit technique to measure the amiloride-sensitive sodium current through the apical membrane of the toad urinary bladder and frog skins, we evaluated the sodium channel-blocking potency of three enantiomeric pairs of amiloride analogs with chiral centers on the side chain. We demonstrated the stereoselectivity in sodium channel blockade of those analogs and confirmed the existence of a second attachment site on the channel for interacting with the lipophilic ligand on the side chain of the analog molecule to enhance its blocking activity. Depending on the separation between the chiral carbon and the pyrazine ring and the chemical groups on the chiral carbon, the eudismic ratio for the 50% inhibition constant of the enantiomers, i.e., the ratio of the sodium channel-blocking potency of the more active enantiomer to that of the less active enantiomer, was found to range from slightly more than 1 to more than 100.

Selective management of gastroschisis according to the degree of visceroabdominal disproportion

OBJECTIVE

This study analyzed the factors influencing the postoperative results after the repair of gastroschisis defects during the past 27 years.

SUMMARY BACKGROUND DATA

The clinical results after the repair of gastroschisis abdominal defects have improved appreciably during the past 25 years, with the long-term survival rate in most large children's centers currently being approximately 90%. The improvement in survival has been largely attributed to advances in perioperative care, frequent use of parenteral nutrition, and better techniques of surgical repair.

METHODS

Between 1965 and 1992, 84 infants with gastroschisis underwent surgical repair. The management of 52 infants after 1979 was compared with that of 32 during the previous 14 years. Associated anomalies were present in 29%. The average birth weight was 2412 g. In 31%, primary fascial closure was performed. In another 31% with moderate visceroabdominal disproportion (VAD), a silastic chimney was used initially, and complete repair was performed at a second operation. For 25% who had severe VAD, more than two operative reconstructions were necessary. Seven of 52 infants with moderate VAD underwent initial skin-flap closure and secondary repair within 12 days.

RESULTS

Almost all complications (27%) and deaths (4%) occurred in infants with severe VAD and were largely unrelated to associated malformations or birth weight. The length of postoperative mechanical ventilation, need for parenteral nutrition, need for multiple operations, and length of hospitalization were all directly related to the severity of the VAD.

CONCLUSIONS

Complete repair of gastroschisis at the initial operation is the optimal goal; however, the severity of VAD has permitted this approach in only one third of patients in this study. Delayed repair with a silastic chimney and one or more reconstructive procedures has provided excellent long-term survival with low morbidity and mortality rates. Although skin-flap closure is no longer used initially, this technique has been helpful for the residual defect in infants with severe VAD who have had multiple silon chimney repairs (Applied Biomaterial, Silverdale, WA).