The membrane binding domains of prostaglandin endoperoxide H synthases 1 and 2. Peptide mapping and mutational analysis

Prostaglandin endoperoxide H synthases 1 and 2 (PGHS-1 and -2) are the major targets of nonsteroidal anti-inflammatory drugs. Both isozymes are integral membrane proteins but lack transmembrane domains. X-ray crystallographic studies have led to the hypothesis that PGHS-1 and -2 associate with only one face of the membrane bilayer through a novel, monotopic membrane binding domain (MBD) that is comprised of four short, consecutive, amphipathic alpha-helices (helices A-D) that include residues 74-122 in ovine PGHS-1 (oPGHS-1) and residues 59-108 in human PGHS-2 (hPGHS-2). Previous biochemical studies from our laboratory showed that the MBD of oPGHS-1 lies somewhere between amino acids 25 and 166. In studies reported here, membrane-associated forms of oPGHS-1 and hPGHS-2 were labeled using the hydrophobic, photoactivable reagent 3-trifluoro-3-(m-[(125)I]iodophenyl)diazirine, isolated, and cleaved with AspN and/or GluC, and the photolabeled peptides were sequenced. The results establish that the MBDs of oPGHS-1 and hPGHS-2 reside within residues 74-140 and 59-111, respectively, and thus provide direct provide biochemical support for the hypothesis that PGHS-1 and -2 do associate with membranes through a monotopic MBD. We also prepared HelA, HelB, and HelC mutants of oPGHS-1, in which, for each helix, three or four hydrophobic residues expected to protrude into the membrane were replaced with small, neutral residues. When expressed in COS-1 cells, HelA and HelC mutants exhibited little or no catalytic activity and were present, at least in part, as misfolded aggregates. The HelB mutant retained about 20% of the cyclooxygenase activity of native oPGHS-1 and partitioned in subcellular fractions like native oPGHS-1; however, the HelB mutant exhibited an extra site of N-glycosylation at Asn(104). When this glycosylation site was eliminated (HelB/N104Q mutation), the mutant lacked cyclooxygenase activity. Thus, our mutational analyses indicate that the amphipathic character of each helix is important for the assembly and folding of oPGHS-1 to a cyclooxygenase active form.

Oxygen radical production by Asian elephant (Elephas maximus) heterophils and Holstein cattle (Bos taurus) neutrophils

Oxidative metabolic burst activity by Asian elephant (Elephas maximus) heterophils and Holstein cattle (Bos taurus) neutrophils was indirectly evaluated by measuring the oxidation of nonfluorescent intracellular 2',7'-dichlorofluorescein (DCFH) to fluorescent 2',7'-dichlorofluorescein (DCF) with flow cytometry. The results were recorded as mean channel fluorescence intensity. Phorbol myristate acetate at 50 ng/ml was used to activate the cells. Elephant heterophils and bovine neutrophils exhibited similar abilities to oxidize intracellular DCFH to DCF, a fluorescent product. A wide range of mean channel fluorescence intensity (1,803-7,393) was observed among individual elephants, and the range of intensities was similar to that observed in bovine neutrophils, supporting the concept of functional heterogeneity of heterophils among elephants.

Pediatric extracranial applications of MR angiography

Extracranial magnetic resonance angiography (MRA) was performed in 20 children to evaluate for various arterial and venous conditions. Time-of-flight and phase-contrast angiograms were constructed using a maximal-intensity-projection algorithm. The accuracy of MRA was comparable to Doppler ultrasound (n = 12) and conventional angiography (n = 3). MRA could provide an excellent mapping of patent (including collaterals) versus thrombosed vessels at sites not evaluated or inaccessible by sonography. Limitations included assessment of small and/or tortuous vessels, severely stenotic lesions, and very slow flow.

The role of arginine 120 of human prostaglandin endoperoxide H synthase-2 in the interaction with fatty acid substrates and inhibitors

Arg-120 is located near the mouth of the hydrophobic channel that forms the cyclooxygenase active site of prostaglandin endoperoxide H synthases (PGHSs)-1 and -2. Replacement of Arg-120 of ovine PGHS-1 with a glutamine increases the apparent Km of PGHS-1 for arachidonate by 1,000-fold (Bhattacharyya, D. K., Lecomte, M., Rieke, C. J., Garavito, R. M., and Smith, W. L. (1996) J. Biol. Chem. 271, 2179-2184). This and other evidence indicate that the guanido group of Arg-120 forms an ionic bond with the carboxylate group of arachidonate and that this interaction is an important contributor to the overall strength of arachidonate binding to PGHS-1. In contrast, we report here that R120Q human PGHS-2 (hPGHS-2) and native hPGHS-2 have very similar kinetic properties, but R120L hPGHS-2 catalyzes the oxygenation of arachidonate inefficiently. Our data indicate that the guanido group of Arg-120 of hPGHS-2 interacts with arachidonate through a hydrogen bond rather than an ionic bond and that this interaction is much less important for arachidonate binding to PGHS-2 than to PGHS-1. The Km values of PGHS-1 and -2 for arachidonate are the same, and all but one of the core residues of the active sites of the two isozymes are identical. Thus, the results of our studies of Arg-120 of PGHS-1 and -2 imply that interactions involved in the binding of arachidonate to PGHS-1 and -2 are quite different and that residues within the hydrophobic cyclooxygenase channel must contribute more significantly to arachidonate binding to PGHS-2 than to PGHS-1. As observed previously with R120Q PGHS-1, flurbiprofen was an ineffective inhibitor of R120Q hPGHS-2. PGHS-2-specific inhibitors including NS398, DuP-697, and SC58125 had IC50 values for the R120Q mutant that were up to 1,000-fold less than those observed for native hPGHS-2; thus, the positively charged guanido group of Arg-120 interferes with the binding of these compounds. NS398 did not cause time-dependent inhibition of R120Q hPGHS-2, whereas DuP-697 and SC58125 were time-dependent inhibitors. Thus, Arg-120 is important for the time-dependent inhibition of hPGHS-2 by NS398 but not by DuP-697 or SC58125.

Follow-up of a decentralized colposcopy program for the investigation and management of cervical intraepithelial neoplasia in the central Canadian Arctic

Cervical intraepithelial neoplasia (CIN) is the second leading cause of cancer in Canadian Inuit women, and the incidence ratio in this population is 3.1 times the Canadian average. In 1993 a program was developed in a regional northern health center (Churchill) to provide colposcopy and loop electrosurgery for women in the Keewatin District of the central Canadian Arctic. Data collected prospectively over the following 2.5 years are presented. One hundred and forty-six women were seen in 341 visits. Indication for referral included CIN I on Pap smear (54.1%), CIN II (34.9%), CIN III (9.6%), and carcinoma of the cervix (1.4%). Large loop excision of the transformation zone was performed at a rate of 9.7 procedures per 100 patient visits. Estimated travel cost-savings attributable to this northern program are $299,200 (Canadian). Use of portable colposcopy in patients' home communities is presently being considered in order to provide enhanced accessibility and further cost-effectiveness.

Cognitive outcome in children and adolescents following severe traumatic brain injury: influence of psychosocial, psychiatric, and injury-related variables

Previous studies of childhood traumatic brain injury (TBI) have emphasized injury-related variables rather than psychiatric or psychosocial factors as correlates of cognitive outcomes. We addressed this concern by recruiting a consecutive series (N = 24) of children age 5 through 14 years who suffered a severe TBI, a matched group who sustained a mild TBI, and a second matched group who sustained an orthopedic injury. Standardized intellectual, memory, psychiatric, family functioning, family psychiatric history, neurological, and neuroimaging assessments were conducted at an average of 2 years following injury. Severe TBI, when compared to mild TBI and orthopedic injury, was associated with significant decrements in intellectual and memory function. A principal components analysis of independent variables that showed significant (p < .05) bivariate correlations with the outcome measures yielded a neuropsychiatric factor encompassing severity of TBI indices and postinjury psychiatric disorders and a psychosocial disadvantage factor. Both factors were independently and significantly related to intellectual and memory function outcome. Postinjury psychiatric disorders added significantly to severity indices and family functioning and family psychiatric history added significantly to socioeconomic status in explaining several specific cognitive outcomes. These results may help to define subgroups of children who will require more intensive services following their injuries.

Posttraumatic stress symptomatology after childhood traumatic brain injury

The purpose of this study was to quantify and to identify predictors of posttraumatic stress disorder (PTSD) symptomatology after traumatic brain injury (TBI). Fifty children aged 6 to 14 years, hospitalized after TBI, were assessed soon after TBI regarding injury severity and preinjury psychiatric, socioeconomic, family functioning, and family psychiatric history status; neuroimaging was also analyzed. Psychiatric assessments were repeated 3, 6, 12, and 24 months after TBI. Only 2 of 46 (4%) subjects with at least one follow-up assessment developed PTSD. However, the frequency with which subjects experienced at least one PTSD symptom ranged from 68% in the first 3 months to 12% at 2 years in assessed children. The presence of an internalizing disorder at time of injury followed by greater injury severity were the most consistent predictors of PTSD symptomatology. It is apparent, therefore, that PTSD and subsyndromal posttraumatic stress disturbances occur despite neurogenic amnesia. These problems should be treated, particularly if symptoms persist beyond 3 months.

Adaptive functioning following traumatic brain injury and orthopedic injury: a controlled study

OBJECTIVE

To study adaptive functioning after severe traumatic brain injury (TBI).

DESIGN

Case-control study.

SETTING

A university hospital and three regional and four community hospitals.

SUBJECTS

A consecutive series (n=24) of children age 5 through 14 years who suffered severe TBI were individually matched to subjects who sustained a mild TBI and to a second group who sustained an orthopedic injury with no evidence of TBI.

MAIN OUTCOME MEASURES

Standardized adaptive functioning, intellectual, psychiatric, and neuroimaging assessments were conducted on average 2 years after injury.

RESULTS

Severe TBI was associated with significantly (p < .05) lower Vineland Adaptive Behavior composite, communication, and socialization standard scores and lower Child Behavior Checklist parent-rated social competence scores compared with children with orthopedic injury. Severe TBI and mild TBI subjects were significantly (p < .05) more impaired than orthopedic subjects on teacher-rated adaptive function. Family functioning, psychiatric disorder in the child, and IQ were significant variables, explaining between 22% and 47% of the variance in adaptive functioning outcomes.

CONCLUSIONS

Severe TBI is associated with significant deficits in child adaptive functioning. This association appears to be mediated by family dysfunction, child psychiatric disorder, and intellectual deficits.

Attention-deficit hyperactivity symptomatology after traumatic brain injury: a prospective study

OBJECTIVE

To study prospectively the course of attention-deficit hyperactivity (ADH) symptomatology in children and adolescents after traumatic brain injury (TBI). It was hypothesized that ADH symptomatology would be significantly related to severity of injury.

METHOD

Subjects were children (n = 50) 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, socioeconomic, family functioning, and family psychiatric history status were conducted. Severity of injury was assessed by standard clinical scales, and neuroimaging was analyzed.

RESULTS

The main finding of this study was that change in ADH symptomatology in the first 2 years after TBI in children and adolescents was significantly related to severity of injury. Overall ADH symptomatology during the study was significantly related to a measure of family dysfunction when family psychiatric history, socioeconomic status, and severity of injury were controlled.

CONCLUSION

The presence of a positive "dose-response" relationship between severity of injury and change in ADH symptoms, present from the 3-month assessment, was consistent with an effect directly related to brain damage.

Psychiatric disorders in children and adolescents after severe traumatic brain injury: a controlled study

OBJECTIVE

To study psychiatric and behavioral morbidity associated with severe traumatic brain injury (TBI).

METHOD

A consecutive series (n = 24) of children aged 5 through 14 years who suffered a severe TBI were matched to subjects who sustained a mild TBI and to a second matched group who sustained an orthopedic injury with no evidence of TBI. Standardized psychiatric, behavioral, and neuroimaging assessments were conducted on average 2 years after injury.

RESULTS

Severe TBI was associated with a significantly higher rate of current "novel" psychiatric disorders (15/24; 63%) compared with children with mild TBI (5/24; 21%) and orthopedic injury (1/24; 4%). Higher effect sizes were evident for child and adolesent self-report of internalizing symptoms rather than externalizing symptoms, for parents' report of overall behavior and internalizing symptoms rather than externalizing symptoms, and for teachers' reports of overall behavior and externalizing symptoms rather than internalizing symptoms.

CONCLUSIONS

Severe TBI is a profound risk factor for the development of a psychiatric disorder. Survivors should be assessed for organic personality syndrome, which is the most common psychiatric disorder after this type of injury.

Cervical spine abnormalities and instability with myelopathy in warfarin-related chondrodysplasia: 17-year follow-up

A patient with warfarin embryopathy developed progressive cervical spinal myelopathy owing to bony cervical spinal damage. While there are several descriptions of warfarin embryopathy, the long-term complication of cervical spinal instability has not been reported. This cervical instability may, as in our patient, cause severe neurological dysfunction or even sudden death; therefore, it is important that pediatric radiologists should be alert to this condition.

Oppositional defiant disorder symptomatology after traumatic brain injury: a prospective study

Our goal was to prospectively study the course of oppositional defiant disorder (ODD) symptomatology in children and adolescents in the first 2 years after traumatic brain injury (TBI). Fifty children aged 6 to 14, hospitalized after TBI, were assessed soon after TBI regarding injury severity; preinjury psychiatric, socioeconomic, family functioning, and family psychiatric history status; and neuroimaging was analyzed. ODD symptomatology in the first year after TBI was related to preinjury family function, social class, and preinjury ODD symptomatology. Increased severity of TBI predicted ODD symptomatology 2 years after injury. Change (from before TBI) in ODD symptomatology at 6, 12, and 24 months after TBI was influenced by socioeconomic status. Only at 2 years after injury was severity of injury a predictor of change in ODD symptomatology. The influence of psychosocial factors appears greater than severity of injury in accounting for ODD symptomatology and change in such symptomatology in the first but not the second year after TBI in children and adolescents. This appears related to persistence of new ODD symptomatology after more serious TBI.

Subcellular localization of prostaglandin endoperoxide H synthases-1 and -2 by immunoelectron microscopy

Prostaglandin endoperoxide H synthases-1 and -2 (PGHS-1 and -2) are the major targets of nonsteroidal anti-inflammatory drugs like aspirin and ibuprofen. These enzymes catalyze the committed step in the formation of prostanoids from arachidonic acid. Although PGHS-1 and -2 are similar biochemically, a number of studies suggest that PGHS-1 and PGHS-2 function independently to form prostanoids that subserve different cellular functions. We have hypothesized that these isozymes may reside, at least in part, in different subcellular compartments and that their compartmentation may affect their access to arachidonic acid and serve to separate the functions of the enzymes. To obtain high resolution data on the subcellular locations of PGHS-1 and -2, we employed immunoelectron microscopy with multiple antibodies specific to each isozyme. Both PGHS-1 and -2 were found on the lumenal surfaces of the endoplasmic reticulum (ER) and nuclear envelope of human monocytes, murine NIH 3T3 cells, and human umbilical vein endothelial cells. Within the nuclear envelope, PGHS-1 and -2 were present on both the inner and outer nuclear membranes and in similar proportions. Western blotting data showed a similar distribution of PGHS-1 and -2 in subcellular fractions, and product analysis using isozyme-specific inhibitors suggested that both enzymes generate the same products in NIH 3T3 cells. Thus, we are unable to attribute the independent functioning of PGHS-1 and PGHS-2 to differences in their subcellular locations. Instead, the independent operation of these isozymes may be attributable to subtle kinetic differences (e.g. negative allosteric regulation of PGHS-1 at low concentrations of arachidonate (500-1000 nM)). A further conclusion of importance from a cell biological perspective is that membrane proteins such as PGHS-1 and -2, which are located on the lumenal surface of the ER, are able to diffuse freely among the ER and the inner and outer membranes of the nuclear envelope.

Shprintzen-Goldberg syndrome: a clinical analysis

Shprintzen-Goldberg syndrome is one of a group of disorders characterized by craniosynostosis and marfanoid habitus. Eleven cases were reported previously. We present 4 new patients and review one of the patients of the original report of Shprintzen and Goldberg [1982: J Craniofac Genet Dev Biol 2:65-74], 15 years later. The clinical and radiologic findings on our patients are compared with those of the previously reported patients and also with those of Furlong et al. [1987: Am J Med Genet 26:599-604] and Lacombe and Battin [1993: Clin Dysmorphol 2: 220-224], who share many of the characteristics of Shprintzen-Goldberg syndrome. Some of the clinical data are helpful in determining if the patients of Furlong et al. [1987: Am J Med Genet 26:599-604] and Lacombe and Battin [1993: Clin Dysmorphol 2: 220-224] have a separate syndrome or represent a variant of Shprintzen-Goldberg syndrome. However, radiologic investigations appear to be more specific, since an abnormality of the first and second cervical vertebrae, hydrocephalus, dilatation of the lateral ventricles, and a Chiari-I malformation of the brain were found only in the patients with Shprintzen-Goldberg syndrome. The apparently diagnostic findings of the 15 patients with this syndrome may be helpful in differentiating between Shprintzen-Goldberg syndrome and other syndromes with craniosynostosis and marfanoid habitus.

Efficacy of a rise in C-reactive protein serum levels as an early indicator of sepsis in burned children

C-Reactive protein serum levels were measured in 57 pediatric patients with 3% to 92% total body surface area burns to determine whether a defined rise in C-reactive protein serum levels could indicate sepsis earlier in burn patients. A rise in C-reactive protein serum levels was defined as an increase of at least 3 mg/dL for 2 days or 10 mg for 1 day. Increases the first 2 days after the burn or the day after surgery were excluded, since these injuries increase C-reactive protein serum levels. Patients were defined as septic when they were on systemic antibiotics and exhibited at least two of 16 specific clinical parameters. C-Reactive protein serum levels correctly predicted sepsis 82% of the time (efficiency=82%). Nonseptic patients generally did not show increased C-reactive protein serum levels (specificity=69%). When sepsis did occur, it always was preceded by increased C-reactive protein (sensitivity=100%), and the increased C-reactive protein occurred 2.3+/-0.5 days before the patient was deemed septic clinically. Hence, a defined rise in C-reactive protein serum levels can predict sepsis sooner in burned children.

Use of reports of previous radiologic studies

RATIONALE AND OBJECTIVES

The purpose of this study was to determine the length of time over which previous radiologic reports were useful during current interpretations and the types of information gathered from the old reports.

MATERIALS AND METHODS

The authors directly observed the use of 209 old reports by radiologists during current radiologic interpretation. They recorded the date of the old report, modality used, and type of information sought. The interpreting radiologists then rated the value of the information in the old report on a Likert scale of 1 (high value) to 4 (minimal value).

RESULTS

In 85% of cases, the most valuable information obtained was found in reports that were less than 2 years old. The most frequently sought types of information were clinical history or the previous radiologist's interpretation.

CONCLUSION

Old reports add value to current interpretation by providing a form of "second reading" and providing clinical history. Two years is sufficient old report access in 85% of situations.

Predictors of family functioning after traumatic brain injury in children and adolescents

OBJECTIVE

To assess factors predictive of family outcome in the first 2 years after traumatic brain injury (TBI) in children and adolescents.

METHOD

Subjects were children aged 6 to 14 at the time they were hospitalized after TBI. The study used a prospective follow-up design. Assessments of preinjury factors (psychiatric family functioning, and family life events), injury factors (severity of injury), and postinjury factors (coping and development of a psychiatric disorder, never before present, i.e., "novel") were conducted using standard clinical scales. The outcome measure was family function as assessed with standardized family functioning interviews (at 12 and 24 months after TBI) and primary caretaker self-report questionnaires (at 3 and 6 months after TBI).

RESULTS

Fifty subjects enrolled, and the analyses focused on 37, 41, 43, and 42 subjects assessed at the 3-, 6-, 12-, and 24-month follow-up evaluations, respectively. The strongest influences on family functioning after childhood TBI are preinjury family functioning, the development of a "novel" psychiatric disorder in the child, and preinjury family life events or stressors.

CONCLUSIONS

These data suggest that there are families, identifiable through clinical assessment, at increased risk for family dysfunction after a child's TBI. Early identification and treatment of the child's psychopathology and family dysfunction may attenuate the associated morbidity.

The Strong Duschinsky Effect and the Intensity of Transitions in Non-Totally Symmetric Vibrations in the Electronic Spectra of Polyatomic Molecules

The effect of strong Duschinsky type mixing of two normal coordinates Q1 and Q2 on the intensity of transitions in non-totally symmetric vibrations in electronic spectra is examined. Using a Fermi resonance type theory, expressions are derived for the intensity of transitions such as 1(1)02(0)1 and 1(1)02(1)0 which gain significant intensity when mixing of coordinates is strong. The results are applied to the 288-nm electronic spectrum of styrene, the 370-nm spectrum of tropolone, and the 281-nm spectrum of 1,4-benzodioxan, all of which provide examples of strong mixing between a pair of normal coordinates. In some cases the theoretical predictions are in general agreement with the observed intensity pattern, if a suitable choice is made of the relevant mixing coefficient. In others there is a divergence which may be related to the importance of other factors such as electrical and mechanical anharmonicity. Copyright 1998 Academic Press. Copyright 1998Academic Press