Nonresolving pneumonia.
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Diagnosis, Differential↗
Biomedical subjects
A Gonzalez
Publications and source records attributed to A Gonzalez.
Interleukin-4 deficiency does not exacerbate disease in NOD mice.
To investigate the role of interleukin (IL)-4 in the regulation of autoimmune diabetes, we crossed the IL-4 knock-out mutation onto the NOD genetic background. This experiment was accelerated by typing for microsatellites linked to known diabetes susceptibility (Idd) loci, and included a control backcross of the wild-type 129/SvJ-derived IL-4 gene, the original target locus. We also crossed the mutation into the BDC2.5 transgenic line, a diabetes model that carries the rearranged T-cell receptor genes from a diabetogenic T-cell clone. The IL-4-null mutation did not accelerate or intensify insulitis in regular NOD mice or in the BDC2.5 transgenic model; it also had no effect on the timing or frequency of the transition to overt diabetes. These data indicate that IL-4 plays no required role in controlling the aggressiveness of murine diabetes.
Alleles↗
Interferon-gamma impacts at multiple points during the progression of autoimmune diabetes.
The role of interferon-gamma in autoimmune diabetes was assessed by breeding a null mutation of the interferon-gamma receptor alpha chain into the nonobese diabetic mouse strain, as well as into a simplified T cell receptor transgenic model of diabetes. In contrast to a previous report on abrogation of the interferon-gamma gene, mutation of the gene encoding its receptor led to drastic effects on disease in both mouse lines. Nonobese diabetic mice showed a marked inhibition of insulitis-both the kinetics and penetrance-and no signs of diabetes; the transgenic model exhibited near-normal insulitis, but this never evolved into diabetes, either spontaneously or after experimental provocation. This failure could not be explained by perturbations in the ratio of T helper cell phenotypes; rather, it reflected a defect in antigen-presenting cells or in the islet beta cell targets.
Animals↗
Cysteine-scanning mutagenesis of helix IV and the adjoining loops in the lactose permease of Escherichia coli: Glu126 and Arg144 are essential. off.
Cys-scanning mutagenesis has been applied to the remaining 45 residues in lactose permease that have not been mutagenized previously (from Gln100 to Arg144 which comprise helix IV and adjoining loops). Of the 45 single-Cys mutants, 26 accumulate lactose to > 75% of the steady state observed with Cys-less permease, and 14 mutants exhibit lower but significant levels of accumulation (35-65% of Cys-less permease). Permease with Phe140-->Cys or Lys131-->Cys exhibits low activity (15-20% of Cys-less permease), while mutants Gly115-->Cys, Glu126-->Cys and Arg144-->Cys are completely unable to accumulate the dissacharide. However, Cys-less permease with Ala or Pro in place of Gly115 is highly active, and replacement of Lys131 or Phe140 with Cys in wild-type permease has a less deleterious effect on activity. In contrast, mutant Glu126-->Cys or Arg144-->Cys is inactive with respect to both uphill and downhill transport in either Cys-less or wild-type permease. Furthermore, mutants Glu126-->Ala or Gln and Arg144-->Ala or Gln are also inactive in both backgrounds, and activity is not rescued by double neutral replacements or inversion of the charged residues at these positions. Finally, a mutant with Lys in place of Arg144 accumulates lactose to about 25% of the steady state of wild-type, but at a slow rate. Replacement of Glu126 with Asp, in contrast, has relatively little effect on activity. None of the effects can be attributed to decreased expression of the mutants, as judged by immunoblot analysis. Although the activity of most of the single-Cys mutants is unaffected by N-ethylmaleimide, Cys replacement at three positions (Ala127, Val132, or Phe138) renders the permease highly sensitive to alkylation. The results indicate that the cytoplasmic loop between helices IV and V, where insertional mutagenesis has little effect on activity [McKenna, E., et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 11954-11958], contains residues that play an important role in permease activity and that a carboxyl group at position 126 and a positive charge at position 144 are absolutely required.
Amino Acid Sequence↗
Enzyme-linked immunoelectrotransfer blot assay for diagnosis of hydatidosis (Echinococcus granulosus) in sheep.
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Animals↗
Calibration and application of an X-ray image intensifier/ charge-coupled device detector for monochromatic macromolecular crystallography.
Charge-coupled device (CCD)-based X-ray detectors allow data to be collected much more quickly (approximately 10 times) than with current on-line imaging-plate systems. At the ESRF, X-ray image intensifier/CCD detector systems have been developed. These have great potential as fast read-out detectors for macromolecular and other forms of crystallography. They are relatively large sensitive X-ray detectors but have two inherent weaknesses: convex detection surfaces leading to spatial distortion and non-uniformity of intensity response, and susceptibility to small changes in magnetic fields. A large improvement has been made to the accuracy obtained by non-uniformity of response calibration and correction, using fluorescence from doped lithium borate glasses. Monochromatic macromolecular crystallography demonstration experiments with external user groups have shown that high-quality results may be obtained under real experimental conditions.
Journal Article↗
Cysteine-scanning mutagenesis of helix II and flanking hydrophilic domains in the lactose permease of Escherichia coli.
Using a functional lactose permease mutant devoid of Cys residues (C-less permease), each amino acid residue in putative transmembrane helix II and flanking hydrophilic loops (from Leu34 to Lys74) was replaced individually with Cys. Of the 41 single-Cys mutants, 28 accumulate lactose to > 70% of the steady state observed with C-less permease, and an additional 10 mutants exhibit lower but significant levels of accumulation (25-60% of C-less). His35-->Cys permease exhibits very low activity (ca. 20% of C-less), while Gly64-->Cys or Asp68-->Cys permease is unable to accumulate lactose. However, His35 can be replaced with Arg without effect on transport activity [Padan, E., Sarkar, H.K., et al. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 6765-6768]. In addition, even though mutant Gly64-->Cys or Glu68-->Cys is inactive both in the C-less background and in the wild-type, neither Gly64 [Jung, K., Jung, H., et al. (1995) Biochemistry 34, 1030-1039] nor Glu68 [Jessen-Marshall, A.E., & Brooker, R.J. (1996) J. Biol. Chem. 271, 1400-1404] is essential for active lactose transport. Immunoloblot analysis reveals that all of the mutants except His35-->Cys permease are inserted into the membrane at concentrations comparable to that of C-less permease. The transport activity of the single-Cys mutants is altered by N-ethylmaleimide (NEM) treatment in a highly specific manner. Most of the mutants are insensitive, but Cys replacements render the permease sensitive to NEM inactivation at positions that cluster in a manner indicating that they are on one face of an alpha-helix (Thr45-->Cys, Gly46-->Cys, Phe49-->Cys, Ser53-->Cys, Ser56-->Cys, Gln60-->Cys, and Ser67-->Cys). Interestingly, the same face contains positions where Cys substitution itself leads to low transport activity (Ile52-->Cys, Leu57-->Cys, Gln60-->Cys, and Gly64-->Cys). The results demonstrate that although no residue per se in this region of the permease is irreplaceable, the surface of one face of helix II is important for active lactose transport.
Amino Acid Sequence↗
Increased incidence of sighs (augmented inspiratory efforts) during synchronized intermittent mandatory ventilation (SIMV) in preterm neonates.
A reflex resulting in a deep, sigh-like inspiratory effort (augmented breath) is frequently triggered during synchronized mechanical ventilation in preterm infants. We studied the incidence of augmented inspiratory efforts and their effect on ventilation and lung compliance during conventional IMV and synchronized IMV (SIMV) in 15 preterm neonates (GA 26.7 +/- 1.5 wks (mean +/- SD), BW 925 +/- 222 g, age 1-8 days). Augmentation of spontaneous inspiratory effort was defined as an esophageal pressure deflection occurring coincident with a synchronized mechanical breath and exceeding the previous unassisted spontaneous effort by more than 50%. The incidence of augmented breaths was higher during SIMV (11.1 +/- 7.7%; P < 0.01) than during conventional IMV (5.1 +/- 6.1%). However, when the synchronized breaths were triggered late (200-300 msec) after the onset of inspiration, augmented breaths occurred no more frequently than during conventional IMV (6.0 +/- 4.7%). The incidence of augmented breaths correlated inversely with dynamic lung compliance (P = 0.014), but was not significantly influenced by a change in PEEP. Although inspiratory effort increased nearly three times during the augmented breaths, tidal volume increased only 12%. The change in tidal volume was limited because the augmented effort reached its maximal negativity only approximately 500 ms after the beginning of the synchronized, mechanical breath and at a time when the mechanical breath had already ended. For this reason the augmented effort did not contribute significantly to minute ventilation, but only prolonged inspiration. Dynamic lung compliance did not change significantly after an augmented breath. The results indicate that augmented inspiratory efforts are more common in preterm neonates ventilated with SIMV than with conventional IMV, but do not contribute significantly to ventilation.
Cohort Studies↗
Gamma knife pallidotomy: case report.
We report a case of gamma knife pallidotomy resulting in a permanent contralateral homonymous hemianopsia and transient contralateral hemiparesis with some improvement in contralateral parkinsonian symptoms. This case illustrates the risk of gamma knife pallidotomy which precludes physiologic target localization and can subject structures surrounding the target to a significant radiosurgical dose. Until noninvasive physiologic target localization is available gamma knife pallidotomy and thalamotomy should be limited to patients with an unacceptably high risk for stereotactic percutaneous thermocoagulation.
Aged↗
Comparison of aceclofenac with piroxicam in the treatment of osteoarthritis.
A multicentre, double-blind, randomised, parallel group study was undertaken to investigate the efficacy and safety of aceclofenac (123 patients, 100 mg twice daily) in comparison to piroxicam (117 patients, 20 mg once daily and placebo once daily) in patients with osteoarthritis of the knee. The treatment period of two months was preceded by a washout period of one week duration. On completion of the study, patients in both aceclofenac and piroxicam-treated groups exhibited significant improvement in pain intensity and functional capacity of the affected knee, as represented by the Osteoarthritis Severity Index (OSI) (p < 0.0001 and p < 0.001 respectively). This was further substantiated following the patient's assessment of pain intensity using the Visual Analogue Scale (VAS), in which significant improvements were demonstrated at all time points for each treatment group (p < 0.001). Although both treatment groups showed a significant improvement in all investigator's clinical assessments (functional exploration of the knee, knee flexion and extension (EXT)), there were no significant differences between the groups. There was, however, a more rapid improvement in knee flexion in the aceclofenac group after 15 days of treatment. Both aceclofenac and piroxicam were well tolerated by patients, the most commonly reported adverse events being gastrointestinal, although their incidence was low. Only 24 patients on aceclofenac, as opposed to 33 on piroxicam complained of dyspepsia, epigastralgia and pyrosis. While 7 patients in each group were withdrawn because of adverse events, only one patient with piroxicam was withdrawn because of severe upper gastrointestinal bleeding. Twice as many reports of fecal blood loss were made in the piroxicam group in comparison to the aceclofenac group. In summary, this study confirms the therapeutic efficacy of aceclofenac and suggests that it is a well-tolerated alternative NSAID to piroxicam in the treatment of osteoarthritis.
Adult↗
Anterior cervical myelopathy in the early postoperative period.
PURPOSE: The onset of anterior cervical myelopathy in the early postoperative period is an unusual complication after cardiac surgery without extracorporeal circulation in which haemodynamic stability was maintained. We report a patient who developed anterior cervical myelopathy after cardiac surgery. CLINICAL FEATURES: A 53-yr-old man with no serious associated medical problems underwent cardiac surgery without extracorporeal circulation to repair a ruptured left ventricle. Haemodynamic stability was maintained throughout the procedure but the patient developed flaccid paraparesis and dissociated sensory loss, three hours later. Early recognition of the clinical picture and prompt initiation of steroid treatment facilitated a successful outcome. The definitive diagnosis was based on magnetic resonance findings days after surgery. CONCLUSION: The onset or aggravation of neurological symptoms in the postoperative period may be avoided by thorough search for medullary pathology in the patient's background and by using particular care when performing manoeuvres during the perioperative period, not only to ensure haemodynamic stability, thus preserving medullary perfusion, but also to avoid mechanical compression of a spinal segment.
Cardiac Surgical Procedures↗
Are interpretations of video defecographies reliable and reproducible?
Video defecography is a dynamic investigation which can influence surgical decision making in constipated patients. A study was therefore undertaken to assess the inter and intraobserver variability in video defecography. Specifically, we sought to assess the interpretation of video defecographies by a group of observers with the same training, guidelines and standards. To determine interobserver variation, four independent observers, two blinded to the patient's history, reviewed 100 randomly sequenced video defecographies performed in constipated patients. The presence or absence of sigmoidocele, rectocele, intussusception or prolapse was noted. Adequate or improper function of the puborectalis, anal canal opening, anorectal angle (ARA) and grade of emptying of the rectum were also assessed. Two weeks after the initial assessment, intraobserver variation was determined by a repeat blinded review of unlabelled randomly sequenced studies. The results of interobserver accuracy for sigmoidoceles, rectoceles, intussusception, rectal prolapse, rectal emptying, opening of the anal canal, puborectalis contraction and straightening of the ARA and rectal emptying were 89.5%, 46.0%, 87.5%, 97.5%, 86.5%, 88.5%, 83.0%, and 80.0%, respectively. The intraobserver variations were 88.5%, 83.8%, 80.5%, 94.5%, 77.0%, 84.8%, 80.5% and 85.5%, respectively. Prior knowledge of the patient's history did not significantly influence the outcome. In summery, video defecography has an overall accuracy of 83.3% and as such is a valid tool in assessing constipated patients.
Adolescent↗
The S5-S6 linker of repeat I is a critical determinant of L-type Ca2+ channel conductance.
The alpha1-subunits of the skeletal and cardiac L-type calcium channels (L-channels) contain nearly identical pore regions (P-regions) in each of the four internal homology repeats. In spite of this high conservation of the P-regions, native skeletal L-channels exhibit a unitary conductance that is only about half that of native cardiac L-channels. To identify structural determinants of this difference in L-channel conductance, we have characterized unitary activity in cell-attached patches of dysgenic myotubes expressing skeletal, cardiac, and chimeric L-channel alpha1-subunits. Our results demonstrate that the S5-S6 linker of repeat I (IS5-IS6 linker) is a critical determinant of the difference in skeletal and cardiac unitary conductance. The unitary conductances attributable to the wild-type skeletal (CAC6; approximately 14 pS) and cardiac (CARD1; approximately 25 pS) alpha1-subunits expressed in dysgenic myotubes are identical to those observed in native tissues. Chimeric alpha1-subunits containing skeletal sequence for the first internal repeat and all of the putative intracellular loops (SkC15), the IS5-IS6 linker and the intracellular loops (SkC51), or only the IS5-IS6 linker (SkC49) each exhibit a low, skeletal-like unitary conductance (< or = 17 pS). Constructs in which the IS5-IS6 linker is of cardiac origin (CARD1 and CSk9) display cardiac-like conductance (approximately 25 pS). Unitary conductance and the rate of channel activation are apparently independent processes, since both SkC51 and SkC49 exhibit low, skeletal-like conductance and rapid, cardiac-like rates of ensemble activation. These results demonstrate that the IS5-IS6 linker strongly influences the single channel conductance of L-channels in a manner that is independent from the rate of channel activation.
Amino Acid Sequence↗
Brain tumor and pregnancy.
OBJECTIVE: To establish the indications for surgical intervention, at the appropriate gestational duration, for brain tumors in pregnant women, and to evaluate any association pregnancy hormones may have with the rate of growth or development of complications of brain tumors. METHODS: We observed seven women with brain tumors associated with pregnancy in a series of 126,413 pregnancies from 1983 to 1995. One woman presented with symptoms of intracranial hypertension, and neurologic signs were the first symptoms in two other women. One woman presented with a sudden hemorrhagic lesion, and three had focal seizures. All were evaluated with computed tomography, magnetic resonance imaging, or both. RESULTS: Six of the seven women had surgery; the seventh was treated with radiotherapy because the neuroradiologic studies suggested a quickly growing brainstem glioma. Diagnoses were confirmed on histology in six women: two with meningiomas, two with ependymomas, and two with low-grade astrocytomas (one of these had multiple astrocytomas). Estrogen and progesterone receptors were studied in two cases (one meningioma and one astrocytoma) and were present in both. CONCLUSION: Management of brain tumors should be tailored to the individual patient. There may be a relation between pregnancy hormones and the rate of brain tumor growth mediated through specific intracellular receptors.
Adult↗
Histamine does not potentiate cyclic AMP-mediated amylase secretion in the guinea-pig pancreatic acinar cells.
1. This study investigates the interaction between histamine and the adenylate cyclase systems involved in the secretion of amylase in isolated guinea-pig pancreatic acinar cells. 2. Histamine caused does-related enhancement of amylase release. Similarly, incubation of acini with increasing concentrations of vasoactive intestinal peptide (VIP) resulted in a typical dose-dependent increase in amylase output. 3. When pancreatic acinar cells were incubated with histamine in combination with VIP, amylase secretion did not differ statistically from secretion induced by histamine or VIP alone and was significantly lower than theoretical additivity. Additionally, amylase secretion in the presence of histamine plus forskolin was significantly less than additive. The action of histamine was equally effective as VIP in causing cyclic adenosine monophosphate (cAMP) increase. 4. These results indicate that histamine may exert its secretory effects via the cyclic AMP pathway in the exocrine guinea-pig pancreas.
Amylases↗
Genetic control of diabetes progression.
Autoimmune diabetes in both the human and the nonobese diabetic mouse has elaborate genetics; in the latter case, the disease is influenced by at least 15-20 loci. We anticipated that the genetics would be simpler in the BDC2.5 T cell receptor transgenic mouse model of diabetes, wherein many T cells express a particular diabetogenic specificity. Initiation of insulitis in this model was the same on the two genetic backgrounds analyzed, but the kinetics and penetrance of diabetes were strikingly different, permitting us to focus on genetic influences during a defined window of disease progression. The differences correlated with variations in five genomic intervals, certain ones of which have been previously implicated in susceptibility to autoimmune disease. This reductionist approach indeed simplified the analysis of diabetes susceptibility loci.
Animals↗
GDH3 encodes a glutamate dehydrogenase isozyme, a previously unrecognized route for glutamate biosynthesis in Saccharomyces cerevisiae.
It has been considered that the yeast Saccharomyces cerevisiae, like many other microorganisms, synthesizes glutamate through the action of NADP+-glutamate dehydrogenase (NADP+-GDH), encoded by GDH1, or through the combined action of glutamine synthetase and glutamate synthase (GOGAT), encoded by GLN1 and GLT1, respectively. A double mutant of S. cerevisiae lacking NADP+-GDH and GOGAT activities was constructed. This strain was able to grow on ammonium as the sole nitrogen source and thus to synthesize glutamate through an alternative pathway. A computer search for similarities between the GDH1 nucleotide sequence and the complete yeast genome was carried out. In addition to identifying its cognate sequence at chromosome XIV, the search found that GDH1 showed high identity with a previously recognized open reading frame (GDH3) of chromosome I. Triple mutants impaired in GDH1, GLT1, and GDH3 were obtained. These were strict glutamate auxotrophs. Our results indicate that GDH3 plays a significant physiological role, providing glutamate when GDH1 and GLT1 are impaired. This is the first example of a microorganism possessing three pathways for glutamate biosynthesis.
Ammonium Sulfate↗
Endothelin ETA receptor regulates signaling and ANF gene expression via multiple G protein-linked pathways.
We have characterized the interaction of endothelin (ET) with cultured neonatal rat ventricular myocytes. Binding studies indicate a single population of ETA receptors [53,000 sites/cell, apparent dissociation constant (Kd) for ET-1 approximately 0.07 nM]. Analysis of mRNA levels for ET receptors using 35 cycles of reverse transcriptase-polymerase chain reaction demonstrates the presence of only ETA-receptor message. Studies with ET-1 and a variety of congeners and antagonists indicate that ETA receptors couple to both the stimulation of phosphoinositide turnover and the inhibition of adenylyl cyclase. In myocytes transfected with an atrial natriuretic factor (ANF) promoter linked to a luciferase reporter gene, ET-1 stimulates luciferase expression through an ETA receptor. These data indicate that the ETA receptor is the exclusive receptor on neonatal ventricular myocytes and that this receptor couples to both phosphoinositide hydrolysis and adenylyl cyclase. ET-1 also induces a threefold increase in mitogen-activated protein kinase (MAPK) activity, an effect that is not sensitive to pertussis toxin (PTx). By contrast, ET-stimulated ANF-luciferase expression is partially inhibited by treatment of cells with PTx, suggesting that both PTx-sensitive (Gi) and PTx-insensitive (Gq) pathways mediate the effects of ET-1 on ANF gene expression in neonatal myocytes and that hormonal regulation of ANF expression may utilize pathways in addition to the activation of MAPK.
Animals↗