Eicosapentaenoic and docosahexaenoic acids reduce PGH synthase 1 expression in bovine aortic endothelial cells

To enlighten the mechanism of inhibition of prostacyclin (PGI2) production by n-3 fatty acids, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, cultured endothelial cells were incubated with albumin bound-EPA or -DHA for 22 h. Under these conditions, PGI2 formation in response to bradykinin, calcium ionophore or exogenous arachidonic acid was equally inhibited by 50%, suggesting that the inhibition might occur downstream the phospholipase step, likely at the level of PGH synthase and/or PGI2 synthase activities. Western blot analysis indicated that the mass of the constitutive isoform of PGH synthase (PGH synthase 1), but not PGI2 synthase, was significantly reduced in n-3 fatty acid-enriched cells. In subsequent experiments, PGH synthase 1 mRNA level, measured by northern blotting, was also decreased in n-3 supplemented cells. This reduction was not due to mRNA destabilization. None of these parameters were altered by similar enrichment with oleic acid (OA). These results suggest that EPA and DHA may affect PGH synthase 1 expression, presumably at the transcriptional level.

Preferential activation of HSF-binding activity and hsp70 gene expression in Xenopus heart after mild hyperthermia

We have examined the effect of mild hyperthermia on the pattern of heat shock transcription factor (HSF) binding activity, heat shock protein 70 (hsp70) and hsp30 gene expression and protein denaturation in selected tissues of adult Xenopus namely, heart, hind limb muscle, eye, liver and spleen. In these studies it was found that heart tissue was the most thermally sensitive of all of the tissues examined since maintenance of adult frogs at 26 degrees C resulted in a preferential activation of HSF binding. Thus, heart has a lowered set point temperature for HSF activation compared to the other tissues examined. At 30 degrees C HSF activation was observed in all of the tissues examined. Heart HSF activation at 26 degrees C was correlated with an increase in hsp70 mRNA and Hsp70 protein accumulation. At 28 degrees C the largest amount of hsp70 and hsp30 mRNA accumulation was detected in heart and skeletal muscle compared to other tissues while hsp70 mRNA accumulation was relatively low in spleen and hsp30 mRNA accumulation was not detectable in eyes, liver and spleen. Incubation of adult frogs at 30 degrees C resulted in enhanced hsp70 and hsp30 mRNA accumulation in all of the tissues. Finally, we have used differential scanning calorimetry (DSC) to compare the temperatures at which protein denaturation occurs in heart and liver tissue. The onset of protein denaturation (T0) occurred approximately 8.5 degrees C lower in heart compared to liver. Also the midpoint of the DSC profile (T1/2) was approximately 10.4 degrees C lower in heart than in liver. Thus, heart proteins are generally more thermolabile than proteins in liver tissue. Taken together these data suggest that heart is more sensitive than the other tissues examined with respect to moderate increases in environmental temperature.

Gastrointestinal tumors of childhood

Tumors of the gastrointestinal tract in children are divided into tumors involving the solid organs that bud from the gastrointestinal tract, principally the liver, and tumors intrinsic to the alimentary tract. This article presents a review of the current state of understanding of solid tissue tumors. The human genome project and better understanding of human genetics have led to remarkable changes in the classification and description of tumors of the alimentary tract. This article attempts to summarize these changes to a current classification of the gastrointestinal polyposis syndromes.

Traumatic brain injury in children and adolescents: psychiatric disorders at two years

OBJECTIVE

To extend findings regarding predictive factors of psychiatric outcome from the first to the second year after traumatic brain injury (TBI) in children and adolescents.

METHOD

Subjects were children aged 6 to 14 years at the time they were hospitalized after TBI. The study used a prospective follow-up design. Assessments of preinjury psychiatric, behavioral, adaptive functioning, family functioning and family psychiatric history status were conducted. Severity of injury was assessed by standard clinical scales and neuroimaging was analyzed. The outcome measure was the presence of a psychiatric disorder, not present before the injury ("novel"), during the second year after TBI.

RESULTS

Fifty subjects enrolled, and the analyses focused on 42 subjects followed at 24 months. Severity of injury, preinjury family function, and preinjury lifetime psychiatric history predicted the development of a "novel" psychiatric disorder present in the second year.

CONCLUSION

These data suggest that there are children, identifiable through clinical assessment, at increased risk for "novel" psychiatric disorders in the second year after TBI.

Traumatic brain injury in children and adolescents: psychiatric disorders in the second three months

Psychiatric disorders may be common after traumatic brain injury (TBI) in children, yet there is a death of prospective studies examining this problem. Fifty children aged 6 to 14, hospitalized after TBI, were assessed soon after TBI regarding preinjury psychiatric, behavioral, adaptive, and family functioning, family psychiatric history status and injury severity. The outcome measure was the presence of a "novel" psychiatric disorder (not present before the injury) during the second 3 months after the injury. Forty-two subjects were reassessed at 6 months. Severity of injury, family psychiatric history, and family function predicted a novel psychiatric disorder. Among children suffering a mild/moderate injury, those with preinjury lifetime psychiatric disorders were no longer (as they had been in the first 3 months) at higher risk than those without such a lifetime history. Thus, there appeared to be children, identifiable through clinical assessment, at increased risk for novel psychiatric disorders after TBI.

Pediatric radiology at a rural hospital: value of teleradiology and subspecialty consultation

OBJECTIVE

We performed a field study and subsequent laboratory investigation of pediatric radiology at a small rural hospital. Our investigation had three components: to describe the characteristics of pediatric radiology in a rural primary care facility, to test the diagnostic accuracy of interpretation of pediatric images transmitted by teleradiology, and to compare relative diagnostic accuracy of general and pediatric radiologists who interpreted pediatric images at a rural institution.

MATERIALS AND METHODS

All 196 pediatric radiographs obtained during a 4-month period comprised the database from which we determined practice characteristics. Reports of 153 unselected cases interpreted by general radiologists using teleradiology were compared with interpretation of the same cases by a pediatric radiologist who interpreted the original radiographs. Discrepant cases were further investigated by a receiver-operating-characteristic curve experiment in which general and pediatric radiologists interpreted each case twice: once viewing teleradiologic images and once viewing the original radiographs at another setting. We then compared interpretive accuracy of observers and techniques.

RESULTS

The pediatric radiographs were predominantly simple examinations for common acute disease, particularly pneumonia and fractures. Discrepancies of interpretation between teleradiology and original radiographs, which occurred in 13% of images, showed no significant difference in accuracy of interpretation for either teleradiologic images or original radiographs. Likewise, we found no significant advantage for accuracy of interpretation by general or pediatric radiologists. Receiver-operating-characteristic analysis of 18 discrepant cases showed slightly increased accuracy for interpretation of original radiographs by pediatric subspecialists.

CONCLUSION

Simple pediatric radiographs obtained at a rural primary care institution and transmitted by teleradiology can be adequately interpreted by general radiologists.

Skeletal injuries in the pediatric patient

Immature skeleton is different from adult skeleton with unique vulnerability to acute and chronic injuries at the growth plate. Recognition and differential diagnosis of inflicted skeletal injury are important. Familiarity with the dynamic changes of growing skeleton in normal children is key to the recognition of pathologic states.

Emissivity of rough sea surface for 8-13 num: modeling and verification

The emissivity model for rough sea surface [Remote Sensing Environ. 24, 313-329 (1988)] is inspected in light of the measured surface emissivity. In the presence of moderate wind (5 m/s or less), the emissivity model is found to be adequate for small to moderate view angles. For large view angles, the discrepancy between the computed and the measured emissivity is large, but one can reduce this considerably by incorporating the reflected sea surface emission into the emissivity model. In addition, examination of the spectral variation of the observed and computed emissivity suggests the need for refined measurements of the complex refractive index. An improved model is constructed to calculate the rough sea surface emissivity that can be used to provide accurate estimates of sea surface skin temperatures from remotely sensed radiometric measurements. An important feature of the improved model is that the computed sea surface emissivity is only weakly dependent on wind speed for most view angles used in practice.

Traumatic brain injury in children and adolescents: psychiatric disorders in the first three months

OBJECTIVE

To assess predictive factors of psychiatric outcome in the first 3 months after traumatic brain injury (TBI) in children and adolescents.

METHOD

Subjects were children aged 6 to 14 years at the time they were hospitalized after TBI. The study used a prospective follow-up design. Assessments of preinjury psychiatric, behavioral, adaptive functioning, family functioning, and family psychiatric history status were conducted. Severity of injury was assessed by standard clinical scales and neuroimaging was analyzed. The outcome measure was the development of a psychiatric disorder, never before present ("novel") in a subject during the first 3 months after the TBI.

RESULTS

Fifty subjects enrolled, and the analyses focused on 37 subjects followed up at 3 months. Increasing severity of injury, presence of a lifetime psychiatric disorder, family psychiatric history, family dysfunction, and lower socioeconomic class/preinjury intellectual function predicted the development of a "novel" psychiatric disorder in the first 3 months of follow-up.

CONCLUSIONS

These data suggest that there are children, identifiable through clinical assessment, at increased risk for development of psychiatric disorders in the first 3 months after TBI.

Prostanoid receptors of murine NIH 3T3 and RAW 264.7 cells. Structure and expression of the murine prostaglandin EP4 receptor gene

Prostaglandin endoperoxide H synthase-1 (PGHS-1) is expressed constitutively in murine NIH 3T3 cells and RAW 264.7 cells. PGHS-2 is inducibly expressed in these cells following stimulation with serum or bacterial lipopolysaccharide (LPS), respectively. Reverse transcription-polymerase chain reaction (RT-PCR) analysis established that a variety of G protein-linked and peroxisomal proliferator-activated prostanoid receptors are expressed in both of these cell types. The levels of the EP2 and EP4 prostaglandin E2 (PGE2) receptors and the prostaglandin I2 receptor were changed in these cells by serum or LPS stimulation. Quantitative RT-PCR indicated that the mRNA for the murine EP4 receptor, the butaprost-insensitive PGE2 receptor that couples to Gs, increases 1.5-3-fold in response to serum (NIH 3T3) or LPS (RAW 264.7) with a time course approximating the induction of PGHS-2 expression. To study expression of the EP4 receptor we isolated the mouse EP4 receptor gene; the gene is 10 kilobase pairs (kb) in length and, like other known prostanoid receptor genes, contains three exons and two introns. The first intron is 0.5 kb and is located 16 base pairs (bp) downstream of the translational start site. This is a different location than that of the first introns of other prostanoid receptor genes. The second intron is located immediately following the sixth transmembrane domain at the same position as the second intron of the thromboxane A2 receptor, prostaglandin D2 receptor, prostaglandin I2 receptor, and one of the PGE2 (EP1) receptor genes. A major transcriptional start was detected at -142 bp upstream of the translational start. There are a variety of putative cis-acting elements within 1.5 kb upstream of the translational start site and within the first intron. Promoter analyses of the EP4 receptor gene promoter in RAW 264.7 cells indicated that there is a constitutive negative regulatory region between -992 and -928 bp, a constitutive positive region between -928 and -554 bp, and an LPS/serum-responsive region between -554 and -116 bp.

C-terminal Ser/Pro-Thr-Glu-Leu tetrapeptides of prostaglandin endoperoxide H synthases-1 and -2 target the enzymes to the endoplasmic reticulum

Prostaglandin endoperoxide H synthases-1 and -2 (PGHS-1 and -2) are integral membrane proteins associated with the luminal surface of the endoplasmic reticulum (ER) and the nuclear envelope (NE). The C-terminal sequences of PGHSs end in -Ser/Pro-Thr-Glu-Leu (-S/PTEL), a sequence similar to one of the known ER targeting sequences, -Lys-Asp-Glu-Leu (-KDEL). Previous immunofluorescence studies from our own and another laboratory had indicated that both native ovine (o) PGHS-1 and oPGHS-1 mutants with modified or deleted -PTEL sequences were localized primarily in the ER when the proteins were expressed for 24-40 h following transient transfection of cos-1 cells. However, in characterizing an oPGHS-1 mutant lacking 15 amino acids from the C-terminus (deltaCT15 oPGHS-1), we found that when this mutant was expressed for a shorter period (18 h) following transfection, the enzyme was concentrated near the nucleus in what appeared to be the Golgi apparatus; similar results were observed when the -P/STEL mutants of oPGHS-1 prepared previously (i.e., deltaPTEL, L600N, and L600R oPGHS-1) were retested using the 18-h posttransfection expression time; in contrast, under the same conditions, the native enzyme was localized throughout the cytoplasm (i.e., in the ER). When the cos-1 cells transfected with each of the various C-terminal mutants were treated with Brefeldin A, the immunofluorescent staining was redistributed to the ER, whereas the distribution of native oPGHS-1 was unaffected. A human PGHS-2 (hPGHS-2) mutant in which the C-terminal leucine residue was replaced with an asparagine (hPGHS-2 L604N) was also found to localize to the Golgi apparatus following 18 h expression in transfected cos-1 cells. These results establish that the C-terminal-S/PTEL sequences of both PGHS-1 and PGHS-2 target the enzymes to the ER. PGHS-2 is more highly concentrated in the NE than in the ER, but apparently this isozyme traverses the Golgi apparatus and returns to the ER prior to its becoming concentrated in the NE.

Inflammatory bowel disease in children

Pediatric inflammatory bowel disease is a complex area of pediatric gastrointestinal imaging. Multiple causative factors are discussed with emphasis upon disorders without known or presumed infectious etiology. Conditions discussed include Henoch-Schönlein purpura, Kawasaki disease, Behçet's disease, Crohn's disease, and ulcerative colitis with their respective clinical and radiological findings, differential diagnosis features, plus pertinent extraintestinal manifestations of inflammatory bowel disease.

Regulation of prostaglandin endoperoxide H synthase-2 expression by 2,3,7,8,-tetrachlorodibenzo-p-dioxin

We have examined the molecular mechanisms for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-stimulated prostaglandin synthesis in Mardin Darvey canine kidney cells (MDCK). TCDD stimulates prostaglandin synthesis in these cells, at least in part, by elevating prostaglandin endoperoxide H2 synthase-2 (PGHS-2) levels. TCDD-stimulated transcription of the PGHS-2 gene was maximal (6-fold) within 2 h and resulted in a 100-fold increase in PGHS-2 mRNA and a 25-fold increase in PGHS-2 protein levels by 4 h. Transient transfection experiments using luciferase-reporter plasmids demonstrated that control element(s) responsible for TCDD activation of the murine PGHS-2 promoter in MDCK cells are located in the first 965 nucleotides upstream from the PGHS-2 transcriptional initiation site. A canonical xenobiotic response element, similar to those that control transcription of other well-known TCDD-sensitive genes, is present at position -157, but does not appear to be sufficient for halogenated aromatic hydrocarbon (HAH) activation of the PGHS-2 promoter. TCDD failed to stimulate transcription from the PGHS-2 promoter when reporter plasmids were transfected into Hepa 1c1c7 cells, a line which contains the functional aryl hydrocarbon receptor. It seems likely that inappropriate expression of PGHS-2 may contribute to the toxic effects of TCDD and other HAHs. In particular, PGHS-2 expression may affect those toxic reactions that involve inappropriate cellular growth, such as dermal hyperplasia and tumor formation. It is also likely that elevated synthesis of prostaglandins, which are potent regulators of immune function, could play a role in the immunotoxicity associated with HAH exposure.

Photolabeling of prostaglandin endoperoxide H synthase-1 with 3-trifluoro-3-(m-[125I]iodophenyl)diazirine as a probe of membrane association and the cyclooxygenase active site

Previous studies of the crystal structure of the ovine prostaglandin endoperoxide H synthase-1 (PGHS-1)/S-flurbiprofen complex (Picot, D., Loll, P. J., and Garavito, R. M. (1994) Nature 367, 243-249) suggest that the enzyme is associated with membranes through a series of four amphipathic helices located between residues 70 and 117. We have used the photoactivatable, hydrophobic reagent 3-trifluoro-3-(m-[125I]iodophenyl)diazirine ([125I]TID) which partitions into membranes and other hydrophobic domains to determine which domains of microsomal PGHS-1 are subject to photolabeling. After incubation of ovine vesicular gland microsomes with [125I]TID, ovine PGHS-1 was one of the major photolabeled proteins. Proteolytic cleavage of labeled PGHS-1 at Arg277 with trypsin established that [125I]TID was incorporated into both the 33-kDa tryptic peptide containing the amino terminus and the 38-kDa tryptic peptide containing the carboxyl terminus. This pattern of photolabeling was not affected by the presence of 20 mM glutathione, indicating that the photolabeling observed for PGHS-1 was not due to the presence of [125I]TID in the aqueous phase. However, nonradioactive TID as well as two inhibitors, ibuprofen and sulindac sulfide, which bind the cyclooxygenase active site of PGHS-1, prevented the labeling of the 38-kDa carboxyl-terminal tryptic peptide. These results suggest that [125I]TID can label both the cyclooxygenase active site in the tryptic 38-kDa fragment and a membrane binding domain located in the 33-kDa fragment. Cleavage of photolabeled PGHS-1 with endoproteinase Lys-C yielded a peptide containing residues 25-166 which was labeled with [125I]TID. This peptide contains the putative membrane binding domain of ovine PGHS-1. Our results provide biochemical support for the concept developed from the crystal structure that PGHS-1 binds to membranes via four amphipathic helices located near the NH2 terminus of the protein.

A Dejerine-Sottas neuropathy family with a gene mapped on chromosome 8

The Patient is a 55-year-old black male who belongs to a large family with 9 affected relatives with autosomal dominant Dejerine-Sottas neuropathy (DSN). Onset of his condition was at 2 years of age with steppage gait followed by severe progressive weakness, atrophy, and sensory loss of his legs and hands accompanied by areflexia and thoracolumbar kyphoscoliosis. The patient became wheelchair confined at age 38. At around age 42, the left shoulder became dislocated and the humeral head underwent aseptic necrosis (Charcot joint). Nerve conduction studies showed absent motor and sensory responses for all major nerves tested. Genetic linkage suggested mapping of this DSN gene on chromosome 8qter. A younger brother with similar neurological findings also demonstrated Charcot joints with bone destruction of the joints of the fourth and fifth fingers.

Involvement of prostaglandin endoperoxide H synthase-2 in osteoclast-like cell formation induced by interleukin-1 beta

Interleukin-1 beta (IL-1 beta) stimulates osteoclast-like cell formation via prostaglandin E2 (PGE2) production. However, the regulatory mechanism for the production of PGE2 in bone cells is still unclear. Recently, it has been shown that two prostaglandin endoperoxide H synthase (PGHS) isozymes exist, termed PGSH-1 and PGHS-2. We report here that IL-1 beta induces PGE2 production in bone marrow culture induced by a PGHS-2-dependent mechanism. IL-1 beta stimulated the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNC) and the production of PGE2 in mouse bone marrow cultures. The dose response curves for the indomethacin inhibition of TRAP-positive MNC formation and PGE2 production were nearly identical. Cycloheximide (CHX) suppressed IL-1 beta-induced PGE2 production, suggesting that the production of PGE2 induced by IL-1 beta required de novo protein synthesis. Northern blot analysis determined that IL-1 beta induced PGHS-2 expression by 30 minutes and mRNA levels were maximal by 1-2 h. Cycloheximide potentiated the accumulation of PGHS-2 mRNA linearly up to 8 h. Dexamethasone, an inhibitor of the induction of PGHS-2, inhibited IL-1 beta-induced PGHS-2 mRNA expression and also suppressed IL-1 beta-stimulated formation of TRAP-positive MNC. Furthermore NS-398, as a selective PGHS-2 inhibitor, completely inhibited IL-1 beta-induced TRAP-positive MNC formation. Moreover, IL-1 beta-induced PGHS-2 mRNA expression and formation of TRAP-positive MNC were inhibited by calphostin C, a selective inhibitor of protein kinase C (PKC). These results indicate that IL-1 beta-induced formation of osteoclast-like cells requires PKC activation, induction of PGHS-2, and subsequent prostaglandin synthesis by this enzyme.

Duplex Doppler sonography of changes in portal vein flow in healthy term newborn infants after feeding

To establish reference values for changes in portal venous diameter, angle- corrected maximal flow velocity, and flow in healthy term newborn infants after formula feeding, we studied 20 subjects using duplex Doppler sonography. After feeding, portal venous diameter increased from 3.6 +/- 0.1 (mean +/- standard error of the mean) to 3.9 +/- 0.1 mm at 15 min and decreased to 3.8 +/- 0.1 at 60 min. Maximal flow velocity increased from 24.1 +/- 1.3 cm/s to a maximum of 35.9 +/- 2.4 cm/s at 15 min and decreased to 28.8 +/- 1.5 cm/s at 60 min. Flow increased from 85.0 +/- 7.5 ml/min to a maximum of 153.6 +/- 14.9 ml/min at 15 min with decrease similar to the maximal flow velocity curve. We conclude that formula feeding produces peak portal blood flows of nearly twice the fasting values at 15 min after feeding and returns almost to fasting value by 60 min.

Involvement of arginine 120, glutamate 524, and tyrosine 355 in the binding of arachidonate and 2-phenylpropionic acid inhibitors to the cyclooxygenase active site of ovine prostaglandin endoperoxide H synthase-1

Examination of the crystal structure of the ovine prostaglandin endoperoxide synthase-1 (PGHS-1)/S- flurbiprofen complex (Picot, D., Loll, P.J., and Garavito, R.M. (1994) Nature 367, 243-2491) suggests (a) that the carboxyl group of arachidonic acid interacts with the arginino group of Arg120; (b) that Arg120 forms an important salt bridge with Glu524; and (c) that Tyr355, which is in close proximity to Arg120, could determine the stereochemical specificity of PGHS-1 toward 2-phenylpropionic acid inhibitors. To test these concepts, we used site-directed mutagenesis to prepare ovine PGHS-1 mutants having modifications of Arg120 (R120K, R120Q, R120E), Glu524 (E524D, E524Q, E524K), and Tyr355 (Y355F) and examined the properties of the mutant enzymes expressed in COS-1 cells. All of the mutants retained at least part of their cyclooxygenase and peroxidase activities except the R120E mutant, which had no detectable activity. The Km values of the R120K and R120Q mutants with arachidonic acid were 87 and 3300 microM, respectively, versus 4 microM for native PGHS-1. The R120Q mutant failed to undergo suicide inactivation during catalysis or time-dependent inhibition by flurbiprofen. These results are consistent with Arg120 binding the carboxylate group of arachidonate and suggest that interaction of the carboxylate group of substrates and inhibitors with Arg120 is necessary for suicide inactivation and time-dependent inhibition, respectively. The Km values for the E524D, E524Q, and E524K mutants were not significantly different from values obtained for the native PGHS-1, suggesting that this residue is not importantly involved in catalysis or substrate binding. The effect of modifications of Arg120 and Tyr355 on the stereospecificity of inhibitor binding was determined. Ratios of IC50 values for cyclooxygenase inhibition by D- and L-ibuprofen, a competitive cyclooxygenase inhibitor, were 32, 67, and 7.1 for native PGHS-1, R120Q PGHS-1, and Y355F PGHS-1, respectively. The decreased stereochemical specificity observed with the Y355F PGHS-1 mutant suggests that Tyr355 is a determinant of the stereospecificity of PGHS-1 toward inhibitors of the 2-phenylpropionic acid class.

Calcium-mediated translocation of cytosolic phospholipase A2 to the nuclear envelope and endoplasmic reticulum

Cytosolic phospholipase A2 (cPLA2) is activated by a wide variety of stimuli to release arachidonic acid, the precursor of the potent inflammatory mediators prostaglandin and leukotriene. Specifically, cPLA2 releases arachidonic acid in response to agents that increase intracellular Ca2+. In vitro data have suggested that these agents induce a translocation of cPLA2 from the cytosol to the cell membrane, where its substrate is localized. Here, we use immunofluorescence to visualize the translocation of cPLA2 to distinct cellular membranes. In Chinese hamster ovary cells that stably overexpress cPLA2, this enzyme translocates to the nuclear envelope upon stimulation with the calcium ionophore A23187. The pattern of staining observed in the cytoplasm suggests that cPLA2 also translocates to the endoplasmic reticulum. We find no evidence for cPLA2 localization to the plasma membrane. Translocation of cPLA2 is dependent on the calcium-dependent phospholipid binding domain, as a calcium-dependent phospholipid binding deletion mutant of cPLA2 (delta CII) fails to translocate in response to Ca2+. In contrast, cPLA2 mutated at Ser-505, the site of mitogen-activated protein kinase phosphorylation, translocates normally. This observation, combined with the observed phosphorylation of delta CII, establishes that translocation and phosphorylation function independently to regulate cPLA2. The effect of these mutations on cPLA2 translocation was confirmed by subcellular fractionation. Each of these mutations abolished the ability of cPLA2 to release arachidonic acid, establishing that cPLA2-mediated arachidonic acid release is strongly dependent on both phosphorylation and translocation. These data help to clarify the mechanisms by which cPLA2 is regulated in intact cells and establish the nuclear envelope and endoplasmic reticulum as primary sites for the liberation of arachidonic acid in the cell.

Added value of radiologist consultation to family practitioners in the outpatient setting

PURPOSE

To measure the added value of a radiologist's consultation to the interpretation of radiographs previously read by a family practitioner.

MATERIALS AND METHODS

The authors reviewed 1,674 chest and extremity radiographs previously read by a family practitioner and consulting radiologist. The 196 radiographs in which there was a discrepancy between the family practitioner's and radiologist's report were evaluated by a radiologist and family physician not involved in and blinded to the original interpretations. The overall accuracy of the participants was determined and differences statistically quantified.

RESULTS

The overall sensitivity of the radiologists was greater than that of the family practitioners (92% vs 86%); specificity was not significantly different. For extremity examinations, there were no significant differences in accuracy of the radiologists and family practitioners; the sensitivity of radiologists for chest studies was considerably greater (89% vs 80%). Radiologic consultation was of particular value in the detection of pneumonia and masses.

CONCLUSION

At a family practice center, the radiologist's role for extremity radiographs might be limited to individual consultation, with review of all chest radiographs.

Tracheomalacia before and after aortosternopexy: dynamic and quantitative assessment by electron-beam computed tomography with clinical correlation

To correlate the dynamics of tracheal collapse with clinical upper airway obstruction before and after aortosternopexy, seven boys and three girls (mean age, 10 months) underwent dynamic evaluation of the trachea by electron-beam computed tomography (EBCT). The site, extent, and severity of collapse were correlated with symptomatology and details of operative procedure. When > 50 % area collapse was used as the criterion for tracheomalacia, segmental involvement occurred above the aortic arch in all patients, extending to the aortic arch level in only four. Tracheomalacia involved two or fewer 8-mm levels in seven patients and more than two levels in three. Eight patients underwent one aortosternopexy procedure, resulting in clinical improvement in six and correlating well with EBCT findings. Of the remaining two patients who had single aortosternopexy and did not show clinical and radiographic improvement, one required operative repair of a vascular ring and the other continued to have recurrent respiratory tract infections. On the basis of EBCT findings, two patients required additional innominate arteriopexies: one improved, and the other remained symptomatic, requiring tracheostomy. EBCT is a noninvasive modality that allows preoperative diagnosis of tracheomalacia. More importantly, the operative decision and technique are guided by an objective and quantitative assessment of tracheal collapse.

Radiologic interpretation by family physicians in an office practice setting

BACKGROUND

Radiology is an integral part of the office practice of many family physicians. Nevertheless, data are sparse on the performance of family physicians in this endeavor. This study investigated the performance of family physicians at interpreting radiographs ordered in a free-standing family practice office.

METHODS

A consecutive series of radiographic studies performed at a family practice office during a 3-year period was surveyed. All radiographic studies included in this analysis (N = 1674) were separately interpreted by the family physician ordering the study and an overreading radiologist. If the interpretations agreed, the studies were accepted as having been correctly interpreted. Cases in which the interpretations disagreed were reexamined.

RESULTS

Family physicians correctly interpreted 92.4% of the radiographic studies (95% confidence interval, 91.0 to 93.6). Their accuracy with extremity films (96.0%) was significantly higher than their accuracy with chest films (89.3%, P < .001). Family physicians were more likely to correctly interpret normal films (95.2%) than abnormal ones (85.9%, P < .001). Thirty-five percent of the cases in which there were differences between family physician and radiologist interpretations were correctly interpreted by family physicians.

CONCLUSIONS

Family physicians showed a high degree of accuracy in radiologic interpretation in an office setting. Chest films were inherently more difficult to interpret than extremity films. Because correct interpretation depends on body part examined and the prevalence of disease, the performance of family physicians will probably vary in different practice settings.

Fatty acid substrate specificities of human prostaglandin-endoperoxide H synthase-1 and -2. Formation of 12-hydroxy-(9Z, 13E/Z, 15Z)- octadecatrienoic acids from alpha-linolenic acid

Human prostaglandin-endoperoxide H synthase-1 and -2 (hPGHS-1 and hPGHS-2) were expressed by transient transfection of COS-1 cells. Microsomes prepared from the transfected cells were used to measure the rates of oxygenation of several 18- and 20-carbon polyunsaturated fatty acid substrates including eicosapentaenoic, arachidonic, dihomo-gamma-linolenic > alpha-linolenic (delta 9, 12, 15), gamma-linolenic, and linoleic acids. Comparisons of kcat/Km values indicate that the order of efficiency of oxygenation is arachidonate > dihomo-gamma-linolenate > linoleate > alpha-linolenate for both isozymes; while the order of efficiency was the same for hPGHS-1 and hPGHS-2, alpha-linolenate was a particularly poor substrate for hPGHS-1. Gamma-Linolenate and eicosapentaenoate were poor substrates for both isozymes, but in each case, these two fatty acids were better substrates for hPGHS-2 than hPGHS-1. These studies of substrate specificities are consistent with previous studies of the interactions of PGHS isozymes with nonsteroidal anti-inflammatory drugs that have indicated that the cyclooxygenase active site of PGHS-2 is somewhat larger and more accommodating than that of PGHS-1. The major products formed from linoleate and alpha-linolenate were characterized. 13-Hydroxy-(9Z,11E)-octadecadienoic acid was found to be the main product formed from alpha-linoleate by both isozymes. The major products of oxygenation of alpha-linolenate were determined by mass spectrometry to be 12-hydroxy-(9Z,13E/Z,15Z)-octadecatrienoic acids. This result suggests that alpha-linolenate is positioned in the cyclooxygenase active site with a kink in the carbon chain such that hydrogen abstraction occurs from the omega 5-position in contrast to abstraction of the omega 8-hydrogen from other substrates.

Specificity of expression and effects of eicosanoid mediators in normal physiology and human diseases

The eicosanoids are a family of oxygenated arachidonic acid derivatives that potently mediate diverse physiological and pathophysiological processes. Recent research on eicosanoids has revealed novel pathways of synthesis, a family of related cell membrane receptors, and distinctive roles in cellular functions. There are two cyclooxygenases that convert arachidonic acid to thromboxane and prostaglandins, one of which is localized in the endoplasmic reticulum and the other in the nuclear envelope. The cyclooxygenases differ in their susceptibility to inhibition by nonsteroidal antiinflammatory drugs. The leukotriene-generating pathway consists of a cytosolic perinuclear 5-lipoxygenase, two integral nuclear envelope proteins, termed 5-lipoxygenase-activating protein and LTC4 synthase, and a cytosolic LTA4 hydrolase. Each protein of the leukotriene synthetic pathway is a target for specific pharmacological intervention. Cellular recognition and effects of eicosanoids are mediated by at least 12 different G protein-associated primary receptors, which differ in tissue distribution, signaling mechanisms, and cellular behavior, as well as binding specificity. Transient localized increases in tissue concentrations of eicosanoids and the concurrent upregulation of complementary receptors influence differentiation, migration, and specific activities of cells in immunity and other integrated physiological responses.

The virtual hospital. Providing multimedia decision support tools via the Internet

Physicians in the clinical setting remain isolated from important sources of medical information. The authors have created a multimedia database known as The Virtual Hospital that improves access to current medical data, which is used to improve patient care decisions. The Virtual Hospital is a digital health sciences library stored on a server (computer) at The University of Iowa and delivered via the Internet to inexpensive personal computers in the workplace. The emerging standard of the World Wide Web is used to provide cross-platform distribution.

Imaging evaluation of breast-feeding and bottle-feeding systems

OBJECTIVE

To compare infant sucking and swallowing patterns during feeding with a new artificial nipple and during breast-feeding.

METHODS

Fifteen healthy, term infants were fed successfully for 1 week with use of the new tricut nipple; then each infant's oral cavity was examined during feeding by using real-time ultrasonography. Measurements of nipple length and compression were made, together with observations concerning the integrity of the seal formed by the infant's mouth around the nipple. These data were compared with similar data from previous studies of 16 breast-fed infants.

RESULTS

Although no artificial feeding system exactly simulates breast-feeding, the new tricut nipple was sucked in a manner similar to the way the human nipple is sucked and delivered milk posteriorly to the foramen cecum region of the tongue, just as the breast does.

CONCLUSION

Although further studies are necessary, to evaluate other characteristics of the new tricut nipple, the measurements from this investigation are useful additions to the ultrasound data these investigators have accumulated on various artificial feeding systems. These data may also prove helpful in determining the most appropriate nipples for infants with various feeding disorders.

Expression cloning of an AVP-activated, calcium-mobilizing receptor from rabbit kidney medulla

Arginine vasopressin (AVP) is a nonapeptide that regulates body fluid and blood pressure homeostasis. We have used expression cloning in the Xenopus laevis oocyte system to identify cDNA clones from a rabbit renal medullary expression library encoding an AVP receptor linked to Ca2+ mobilization. cRNA generated from positive clones conferred upon oocytes the capacity to mobilize intracellular Ca2+ in response to AVP. A cDNA clone encoding a protein of 780 amino acids was isolated, sequenced, and subcloned into an SV40-based expression vector. Expression of the cloned protein [designated the vasopressin-activated, calcium-mobilizing (VACM-1) protein] in COS-1 cells, resulted in increased 125I-labeled AVP binding [dissociation constant (Kd) of approximately 2 nM] and increased AVP-induced mobilization of Ca2+. Importantly, 125I-AVP could be immunoprecipitated both from detergent-solubilized membranes from COS-1 cells expressing VACM-1 protein and from an in vitro translation system, in which VACM-1 protein was synthesized, using antibodies prepared against a synthetic peptide derived from the NH2-terminal sequence of VACM-1. Interestingly, immunohistochemical staining of rabbit kidney sections with this antibody showed specific staining of collecting tubule epithelia. The deduced amino acid sequence is not homologous with any nucleic acid or amino acid sequences reported to date, including those of the V1 and V2 AVP receptors. The VACM-1 protein may represent a novel AVP receptor.

Expression-activity profiles of cells transfected with prostaglandin endoperoxide H synthase measured by quantitative fluorescence microscopy

Transfection of cos-1 cells with either prostaglandin endoperoxide H synthase-1 (PGHS-1) or -2 (PGHS-2) results in a mixed population of cells containing a diverse range of expressed enzyme. The use of fluorescent substrates and antibodies, in conjunction with fluorescence microscopy, provides the means to quantitate expression and activity of the enzyme within individual cells. Data obtained from individual cells can be utilized to construct enzyme activity curves for a population of transfected cells. This method has been employed to prepare expression-activity profiles within a population of cos-1 cells expressing PGHS-1 or -2. A direct correlation was observed between enzyme expression and activity as measured in single cells. The data demonstrate that activity-expression analyses can now be performed within single adherent cells growing in tissue culture.

Different intracellular locations for prostaglandin endoperoxide H synthase-1 and -2

The subcellular locations of prostaglandin endoperoxide synthase-1 and -2 (PGHS-1 and -2) were determined by quantitative confocal fluorescence imaging microscopy in murine 3T3 cells and human and bovine endothelial cells using immunocytofluorescence with isozyme-specific antibodies. In all of the cell types examined, PGHS-1 immunoreactivity was found equally distributed in the endoplasmic reticulum (ER) and nuclear envelope (NE). PGHS-2 immunoreactivity was also present in the ER and NE. However, PGHS-2 staining was twice as concentrated in the NE as in the ER. A histofluorescence staining method was developed to localize cyclooxygenase/peroxidase activity. In quiescent 3T3 cells, which express only PGHS-1, histofluorescent staining was most concentrated in the perinuclear cytoplasmic region. In contrast, histochemical staining for PGHS-2 activity was about equally intense in the nucleus and in the cytoplasm, a pattern of activity staining distinct from that observed with PGHS-1. Our results indicate that there are significant differences in the subcellular locations of PGHS-1 and PGHS-2. It appears that PGHS-1 functions predominantly in the ER whereas PGHS-2 may function in the ER and the NE. We speculate that PGHS-1 and PGHS-2 acting in the ER and PGHS-2 functioning in the NE represent independent prostanoid biosynthetic systems.

Biochemistry of prostaglandin endoperoxide H synthase-1 and synthase-2 and their differential susceptibility to nonsteroidal anti-inflammatory drugs

The principal pharmacological effects of nonsteroidal anti-inflammatory drugs (NSAIDs) are due to their ability to inhibit prostaglandin synthesis. NSAIDs block the cyclooxygenase activities of the closely related PGH synthase-1 and PGH synthase-2 (PGHS-1 and PGHS-2) isozymes. NSAIDs are therapeutically useful due to their analgesic, anti-pyretic, anti-inflammatory, and anti-thrombogenic properties. Major side-effects of NSAIDs include their ulcerogenic and nephrotoxic activities. All clinically approved NSAIDs in general use today inhibit both PGHS-1 and PGHS-2. Recently, inhibitors have been identified that are selective toward PGHS-2 and that have potent analgesic and anti-inflammatory activities with minimal ulcerogenic activity. If the new PGHS-2 selective NSAIDs can effectively inhibit inflammatory prostaglandin synthesis by PGHS-2, without inhibiting PGHS-1 prostaglandin synthesis required to regulate sodium and water resorption, and renal blood flow, it is likely that these new drugs will also have significantly less renal toxicity than present-day NSAIDs. In this article, the mechanisms of actions of NSAIDs primarily at the biochemical level, including the reactions catalyzed by PGHSs, will be discussed. In addition, the biochemical properties of these isozymes, and the differential regulation of the PGHS-1 and PGHS-2 genes, will be examined.