Pyoderma gangrenosum in two siblings: a familial predisposition

We report pyoderma gangrenosum in two siblings with onset during childhood and no associated systemic abnormalities. The patients were born of nonconsanguineous, healthy parents. Treatment with oral corticosteroids produced an excellent clinical response, followed by recurrence after cessation of therapy. Steroids were restarted in combination with dapsone to prevent further recurrence.

Congenital syphilis and fluorescent treponemal antibody test reactivity after the age of 1 year

BACKGROUND

Many believe that a persistently reactive fluorescent treponemal antibody absorption (FTA-ABS) is manifested with congenital syphilis after the age of 1 year, that it is useful in the retrospective diagnosis of children with congenital syphilis, and that it can be used to confirm other treponemal tests.

GOAL

To determine whether a reactive FTA-ABS after the age of 12 months is indicative of congenital syphilis.

STUDY DESIGN

Prospective outpatient follow-up evaluation until at least the age of 12 months was conducted for 194 babies born to mothers with reactive syphilis serology at delivery, and for two additional children with congenital syphilis diagnosed when they were younger than 1 year (total, 196 children).

RESULTS

In the study group, 54 children had reactive FTA-ABS (reactors) until the age of at least 12 months or more, and 142 children had nonreactive FTA-ABS (nonreactors) at the age of 12 months or more. Of the 54 reactors, 17 (31%) had evidence of congenital syphilis at birth, whereas evidence of congenital syphilis was seen in 14 of the 142 (10%) nonreactors (P = 0.0002). At 15 months, nonreactive FTA-ABS developed in six reactors, and eventually in 15 of 44 reactors (34%) tested.

CONCLUSIONS

A reactive FTA-ABS may be seen at 12 months in children with and without evidence of congenital syphilis at birth. Not all children with congenital syphilis will manifest reactive FTA-ABS at 12 months, and FTA-ABS reactivity wanes with time.

Erythrocyte deformability is a nitric oxide-mediated factor in decreased capillary density during sepsis

Erythrocyte deformability has been recognized as a determinant of microvascular perfusion. Because nitric oxide (NO) is implicated in the modulation of red blood cell (RBC) deformability and NO levels increase during sepsis, we tested the hypothesis that a NO-mediated decrease in RBC deformability contributes to decreased functional capillary density (CD) in remote organs. With the use of a peritonitis model of sepsis in the rat [cecal ligation and perforation (CLP)] and aminoguanidine (AG) to prevent increases in NO, we measured CD in skeletal muscle (intravital microscopy), mean erythrocyte membrane deformability (; micropipette aspiration), systemic NO production [plasma nitrite/nitrate (NO(x)) chemiluminescence], and NO accumulation in RBC [NO bound to hemoglobin (HbNO) detected by electron paramagnetic resonance spectroscopy]. In untreated CLP animals relative to sham, NO(x) increased 254% (P < 0.05), stopped flow capillaries increased 149% (P < 0.05), and decreased 12.7% (P < 0.05), with a subpopulation (5%) of RBC with deformabilities below the normal range. AG prevented increases in NO(x), accumulation of HbNO, and decreases in both and functional CD. We found no evidence of leukocyte plugging postcapillary venules. Our findings suggest that decreased functional CD during sepsis resulted from a NO-mediated decrease in erythrocyte deformability.

Molecular mechanisms regulating the differential association of kainate receptor subunits with SAP90/PSD-95 and SAP97

Recent studies have demonstrated that kainate receptors are associated with members of the SAP90/PSD-95 family (synapse-associated proteins (SAPs)) in neurons and that SAP90 can cluster and modify the electrophysiological properties of GluR6/KA2 kainate receptors when co-expressed in transfected cells. In vivo, SAP90 tightly binds kainate receptor subunits, while SAP97 is only weakly associated, suggesting that this glutamate receptor differentially associates with SAP90/PSD-95 family members. Here, green fluorescent protein (GFP)-tagged chimeras and deletion mutants of SAP97 and SAP90 were employed to define the molecular mechanism underlying their differential association with kainate receptors. Our results show that a weak interaction between GluR6 and the PDZ1 domain of SAP97 can account for the weak association of GluR6 with the full-length SAP97 observed in vivo. Expression studies in HEK293 cells and in vitro binding studies further show that although the individual Src homology 3 and guanylate kinase domains in SAP97 can interact with the C-terminal tail of KA2 subunit, specific intramolecular interactions in SAP97 (e.g. the SAP97 N terminus (S97N) binding to the Src homology 3 domain) interfere with KA2 binding to the full-length molecule. Because receptor subunits are known to segregate to different parts of the neuron, our results imply that differential association of kainate receptors with SAP family proteins may be one mechanism of subcellular localization.

Relative contribution of hemopoietic and pulmonary parenchymal cells to lung inducible nitric oxide synthase (inos) activity in murine endotoxemia

Acute lung injury is an important feature of sepsis and increased iNOS expression and NO production contribute to the pathogenesis of this syndrome. We generated bone marrow-transplanted chimeric mice with iNOS expression limited to either inflammatory or pulmonary parenchymal cells, and assessed pulmonary iNOS activity and systemic levels of NO metabolites in an endotoxemic model of sepsis. We found that while both pulmonary parenchymal cells and inflammatory cells contribute to the increased lung iNOS activity in endotoxemia, pulmonary parenchymal cells contribute to a significantly greater degree. Using measurement of plasma NO(-)(x), whole body NO production was assessed in this model. We found that the main source of NO(-)(x) was again, parenchymal cells and not inflammatory cells. This is the first study to demonstrate that most of the increased NO production in this model of endotoxemic sepsis derives from parenchymal cells rather than inflammatory cells.

Reciprocal regulation of anaerobic and aerobic cell wall mannoprotein gene expression in Saccharomyces cerevisiae

The DAN/TIR genes encode nine cell wall mannoproteins in Saccharomyces cerevisiae which are expressed during anaerobiosis (DAN1, DAN2, DAN3, DAN4, TIR1, TIR2, TIR3, TIR4, and TIP1). Most are expressed within an hour of an anaerobic shift, but DAN2 and DAN3 are expressed after about 3 h. At the same time, CWP1 and CWP2, the genes encoding the major mannoproteins, are down-regulated, suggesting that there is a programmed remodeling of the cell wall in which Cwp1 and Cwp2 are replaced by nine anaerobic counterparts. TIP1, TIR1, TIR2, and TIR4 are also induced during cold shock. Correspondingly, CWP1 is down-regulated during cold shock. As reported elsewhere, Mox4 is a heme-inhibited activator, and Mot3 is a heme-induced repressor of the DAN/TIR genes (but not of TIP1). We show that CWP2 (but not CWP1) is controlled by the same factors, but in reverse fashion-primarily by Mot3 (which can function as either an activator or repressor) but also by Mox4, accounting for the reciprocal regulation of the two groups of genes. Disruptions of TIR1, TIR3, or TIR4 prevent anaerobic growth, indicating that each protein is essential for anaerobic adaptation. The Dan/Tir and Cwp proteins are homologous, with the greatest similarities shown within three subgroups: the Dan proteins, the Tip and Tir proteins, and, more distantly, the Cwp proteins. The clustering of homology corresponds to differences in expression: the Tip and Tir proteins are expressed during hypoxia and cold shock, the Dan proteins are more stringently repressed by oxygen and insensitive to cold shock, and the Cwp proteins are oppositely regulated by oxygen and temperature.

Cytochrome P450 metabolites of arachidonic acid but not cyclooxygenase-2 metabolites contribute to the pulmonary vascular hyporeactivity in rats with acute Pseudomonas pneumonia

We have previously demonstrated depressed vascular contractility in intralobar pulmonary artery (PA) rings isolated from rats with acute Pseudomonas pneumonia. Here we describe the role of arachidonic acid (AA) metabolites in the regulation of pulmonary vascular tone in inflammation. Pneumonia was induced by intratracheal injection of P. aeruginosa organisms. Rats were sacrificed 44 h later. EETs and 20-HETE were formed at significantly lower rates in pneumonia compared with control lung microsomes. Vasoactive effects of CYP metabolites (5,6-EET, 8,9-EET, 11,12-EET, 14,15-EET, and 20-HETE) on small PA rings from control or pneumonia rats were assessed in vitro. All four EETs and 20-HETE were more potent PA vasoconstrictors than KCl or phenylephrine (PE). However, this potency was attenuated in PA rings from pneumonia lungs compared with control. In contrast, pneumonia had no effect on COX activity [total pulmonary prostaglandin (PG), PGE(2), and 6-keto-PGF(1 alpha)]. In vitro vascular contractility to KCl, PE, or PGF(2 alpha) was assessed in small PA rings from control and pneumonia rats in the presence and absence of the COX-2 inhibitor NS-398 (10 microM). NS-398 did not reverse the attenuated contractile responses to KCl, PE, or PGF(2 alpha) in pneumonia rats. Nitrite/nitrate levels, inducible nitric-oxide synthase and heme oxygenase activities were all significantly elevated in pneumonia lungs. In conclusion, vasodilator PGs produced by COX-2 do not contribute to the depressed PA contractility in this model of pneumonia. Depressed pulmonary production and vasoconstrictor effects of CYP metabolites of AA (possibly due to increased NO and/or carbon monoxide) indicate a potential role for these vasoactive metabolites in this model of acute pneumonia.

Thyroid hormone profile in obese subjects--a clinical study

Fifty obese subjects with body weight above 120% of the ideal weight for that height or body mass index greater than 27.8 kg/m2 in men or 27.3 kg/m2 in women were studied for thyroid hormone profile. Nearly three-fourths obese subjects had body mass index of 30-40 kg/m2. Eighty-six per cent subjects were clinically and biochemically euthyroid. Fourteen per cent of the subjects had hypothyroidism; out of them, 8% were clinically and biochemically hypothyroid while 6% were only biochemically hypothyroid. None of the hypothyroid subjects had morbid obesity (greater than 40 kg/m2 body mass index). Duration of obesity in hypothyroid subjects was less than 10 years in nearly three-fourths of cases.

Noninvasive measurement of exhaled nitric oxide in a spontaneously breathing mouse

Nitric oxide (NO) has been detected in the exhaled gas of animals and humans. In previous work, investigators have used anesthetized, mechanically ventilated animals to obtain exhaled NO (E(NO)) measurements, which has unclear effects on the levels of E(NO) and does not allow for repeated analysis of E(NO). We sought to measure E(NO) from a single, spontaneously breathing mouse. The mouse was placed in a small Plexiglas chamber and allowed to acclimatize before exhaled gas was collected for E(NO) analysis. Under optimal operating conditions of flow and pressure, the mean concentration of exhaled NO (FE(NO)) of 25 mice was 10.1 +/- 1.0 ppb. The maximal variation of FE(NO) when repeatedly measured daily in individual animals was 2.1 ppb. Administration of L-NAME, a nonselective NOS inhibitor, reduced FE(NO) by 51 +/- 6% (p < 0.01). Intraperitoneally administered lipopolysaccharide induced acute lung injury and increased FE(NO) by 30 +/- 7% (p < 0.05). We have demonstrated that it is possible to noninvasively measure E(NO) from a single, spontaneously breathing mouse. This novel technique provides a stable, reproducible, and responsive measure of E(NO) in mice. This technique will be of use in determining cellular and isoform sources of E(NO), as well as the role of endogenous NO in lung disease.

Unusually severe ABO hemolytic disease of newborn

ABO-hemolytic disease of newborn (ABO-HDN) is a common cause of neonatal hyperbilirubinemia. Most of the cases are however mild. We describe a neonate with ABO-HDN with unusually severe course.

Surgical emphysema--an unusual finding in spontaneous neonatal gastric perforation

A neonate presented with extensive surgical emphysema of the abdominal wall and a spontaneous gastric perforation. This clinical presentation is very rare. Early diagnosis and treatment improve the clinical outcome.

Leak compensation in positive pressure ventilators: a lung model study

Leak compensating abilities of six different positive pressure ventilators commonly used to deliver noninvasive positive pressure ventilation, including the bilevel positive airway pressure (BiPAP) S/T-D and Quantum (Respironics Inc, Murrysville, PA, USA), 335 and O'NYX (Mallinckrodt Inc, St Louis, MO, USA), PLV 102 (Respironics), and Siemens Servo 900C (Siemens Inc, Danvers, MA, USA). Using a test lung model, compensatory capabilities of the ventilators were tested for smaller and larger leaks using the assist/control or timed modes. Back-up rate was 20 min(-1), inspiratory pressure was 18 cmH2O, and expiratory pressure was 5 cmH2O. It was found that even in the absence of air leaking, delivered tidal volume differed substantially between the ventilators during use of pressure-targeted modes, depending on inspiratory flows, inaccuracies in set versus delivered pressures, and inspiratory duration. Also during pressure-targeted ventilation, increasing the tI/ttot up to, but not beyond, 0.5 improved compensation by lengthening inspiratory duration, whereas use of a sensitive flow trigger setting tended to cause autocycling during leaking, interfering with compensation. Leaking interfered with cycling of the BiPAP S/T, inverting the I:E ratio, shortening expiratory time, and reducing delivered tidal volume. Volume-targeted modes achieved limited compensation for small air leaks, but compensated poorly for large leaks. To conclude, leak-compensating capabilities differ markedly between ventilators but pressure-targeted ventilators are preferred for noninvasive positive pressure ventilation in patients with substantial air leaking. Adequate inspiratory flows and durations should be used, triggering sensitivity should be adjusted to prevent autocycling, and a mechanism should be available to limit inspiratory time and avoid I:E ratio inversion.

Hepatitis C: a review and update

The hepatitis C virus is an RNA virus that is a major cause of acute and chronic hepatitis. It is contracted chiefly through parenteral exposure to infected material such as blood transfusions or injections with dirty needles. Those at highest risk for development of hepatitis C are injection-drug users, people who snort cocaine with shared straws, and health care workers who are at risk for needle-stick and other exposures. Although the incidence of acute hepatitis C infection has fallen dramatically in the United States during the past decade, the prevalence of infection remains high (approximately 2.7 million Americans) because chronic hepatitis C develops in about 75% of those infected. Both acute and chronic hepatitis C are asymptomatic in most patients. However, chronic hepatitis C is a slowly progressive disease and results in severe morbidity in 20% to 30% of infected persons. Chronic hepatitis C is associated with a host of extrahepatic manifestations, many of which may be seen by dermatologists. The most frequent of these are mixed cryoglobulinemia with leukocytoclastic vasculitis and porphyria cutanea tarda. (J Am Acad Dermatol 2001;44:159-79.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be familiar with the essentials of the virology of the hepatitis C virus and the major features of the human diseases caused by hepatitis C viral infection; the extrahepatic manifestations of hepatitis C viral infection, with particular emphasis upon dermatologic manifestations, including leukocytoclastic vasculitis, porphyria cutanea tarda, and lichen planus; and the current methods of management of hepatitis C and its extrahepatic manifestations.

Syntheses of pyrrolo- and indoloisoquinolinones by intramolecular cyclizations of 1-(2-arylethyl)-5-benzotriazolylpyrrolidin-2-ones and 3-benzotriazolyl-2-(2-arylethyl)-1-isoindolinones

1,5,6,10b-Tetrahydropyrrolo[2,1-alpha]isoquinolin-3(2H)-ones 17a,b, 17d,e, and 5,12b-dihydroisoindolo[1,2-alpha]isoquinolin-8(6H)-ones 22a-e were prepared by intramolecular cyclizations of 1-(2-arylethyl)-5-benzotriazolyl-pyrrolidin-2-ones 15a,b, 15d,e, and 3-benzotriazolyl-2-(2-arylethyl)-1-isoindolinones 20a-e, respectively, in the presence of titanium chloride. Products from chiral amines were obtained with stereoselectivities of > or = 94%.

Utility of routine chest radiographs in a medical-surgical intensive care unit: a quality assurance survey

OBJECTIVE

To determine the utility of routine chest radiographs (CXRs) in clinical decision-making in the intensive care unit (ICU).

DESIGN

A prospective evaluation of CXRs performed in the ICU for a period of 6 months. A questionnaire was completed for each CXR performed, addressing the indication for the radiograph, whether it changed the patient's management, and how it did so.

SETTING

A 14-bed medical-surgical ICU in a university-affiliated, tertiary care hospital.

PATIENTS

A total of 645 CXRs were analyzed in 97 medical patients and 205 CXRs were analyzed in 101 surgical patients.

RESULTS

Of the 645 CXRs performed in the medical patients, 127 (19.7%) led to one or more management changes. In the 66 surgical patients with an ICU stay <48 hours, 15.4% of routine CXRs changed management. In 35 surgical patients with an ICU stay > or = 48 hours, 26% of the 100 routine films changed management. In both the medical and surgical patients, the majority of changes were related to an adjustment of a medical device.

CONCLUSIONS

Routine CXRs have some value in guiding management decisions in the ICU. Daily CXRs may not, however, be necessary for all patients.

The complete genomic sequence of a BLV strain from a Holstein cow from Argentina

DNA was extracted from the peripheral blood of a seropositive, PCR-positive, BLV-infected Holstein cow (No. 38) from Argentina. The DNA was amplified via PCR with a series of overlapping primers encompassing the entire BLV proviral DNA. The amplified BLV ARG 38 DNA was cloned, sequenced, and compared phylogenetically to three other full-length BLV sequences. Characterization of its deduced proteins and its relationship to other members of the PTLV/BLV genus of retroviruses are discussed.

Combined cytotoxic action of paclitaxel and ceramide against the human Tu138 head and neck squamous carcinoma cell line

PURPOSE

Paclitaxel, a chemotherapeutic agent used in the treatment of recalcitrant ovarian and breast as well as other neoplasms, is being investigated for the treatment of squamous cell carcinoma of the head and neck. Our previous studies have demonstrated that exogenously added ceramide enhances apoptosis in paclitaxel-exposed human leukemic cells. In this study, we showed that exogenous ceramide augmented paclitaxel-induced apoptosis in Tu138 cells in vitro when added simultaneously in combination with the paclitaxel.

METHODS

The combined cytotoxic effects of paclitaxel and ceramide exposure against Tu138 cells were assessed by an MTT dye assay, cell cycle analysis, TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) assay, and isobologram analysis for synergistic activity.

RESULTS

The MTT dye assay results indicated augmentation of time- and concentration-dependent paclitaxel-mediated cell cytotoxicity by simultaneous ceramide treatment. Paclitaxel treatment of Tu138 cells also resulted in an accumulation of cells in the G2-M phase of the cell cycle. This paclitaxel-mediated G2-M phase accumulation decreased significantly with the addition of ceramide, indicating that combined paclitaxel/ceramide treatment resulted in the elimination of Tu138 cells from the S and/or G2-M phases of the cell cycle. Furthermore, ceramide enhancement of paclitaxel-mediated apoptosis was also detected by the TUNEL assay.

CONCLUSION

Our results suggest that paclitaxel/ceramide combination therapy may be an attractive alternative to conventional methods of chemotherapy for head and neck cancer, and should be further explored.

Pulmonary microvascular changes during sepsis: evaluation using intravital videomicroscopy

A variety of pulmonary microvascular changes occur during sepsis. These include abnormal vascular reactivity, leukocyte sequestration, and leakage of protein into the alveoli. Based on intravital videomicroscopy we have developed a method to directly assess in vivo the changes that occur in the pulmonary microcirculation in a rat model of sepsis. Male Sprague-Dawley rats were assigned to control or sepsis groups. Sepsis was induced by cecal ligation and perforation. Twenty four hours later, rats were anesthetized, mechanically ventilated, and their lung prepared for intravital videomicroscopy. A specially designed transparent thoracic window was inserted into the chest wall. The dependent surface of the lung was superfused with saline solution and visualized with an inverted microscope. Vascular contractility, to phenylephrine, (PE) and hypoxia of small (15-25 microm in diameter) and medium (40-50 microm) arterioles was examined. Leukocyte traffic in the pulmonary microcirculation was studied after in vivo labeling of leukocytes with Rhodamine and visualized with fluorescence microscopy. Leak of albumin into the alveolar space was measured with FITC-labeled albumin and fluorescence microscopy. Both small and medium sized pulmonary arterioles in septic animals exhibited attenuated vascular contractility to phenylephrine, but only medium-sized arterioles displayed hypocontractility to hypoxia. Further, in septic animals there was an increase in both the number of stationary leukocytes in the pulmonary microcirculation and an increase in alveolar capillary protein leak. We conclude: (1) direct visualization of the pulmonary microvascular pressor response to hypoxia and PE in the rat is possible using this technique, (2) similar to previous in vitro studies with larger vessels, pulmonary arterioles have an attenuated contractile response to PE and hypoxia in sepsis, and (3) there is an increase in both the number of stationary leukocytes and protein leak into the alveolus in the lungs of septic animals.

Differential requirement for classic and novel PKC isoforms in respiratory burst and phagocytosis in RAW 264.7 cells

The binding of Ab (IgG)-opsonized particles by FcgammaRs on macrophages results in phagocytosis of the particles and generation of a respiratory burst. Both IgG-stimulated phagocytosis and respiratory burst involve activation of protein kinase C (PKC). However, the specific PKC isoforms required for these responses have yet to be identified. We have studied the involvement of PKC isoforms in IgG-mediated phagocytosis and respiratory burst in the mouse macrophage-like cell line, RAW 264.7. Like primary monocyte/macrophages, their IgG-mediated phagocytosis was calcium independent and diacylglycerol sensitive, consistent with novel PKC activation. Respiratory burst in these cells was Ca2+ dependent and inhibited by staurosporine and calphostin C as well as by the classic PKC-selective inhibitors Gö 6976 and CGP 41251, suggesting that classic PKC is required. In contrast, phagocytosis was blocked by general PKC inhibitors but not by the classic PKC-specific drugs. RAW 264.7 cells expressed PKCs alpha, betaI, delta, epsilon, and zeta. Subcellular fractionation demonstrated that PKCs alpha, delta, and epsilon translocate to membranes during phagocytosis. In Ca2+-depleted cells, only novel PKCs delta and epsilon increased in membranes, and the time course of their translocation was consistent with phagosome formation. Confocal microscopy of cells transfected with green fluorescent protein-conjugated PKC alpha or epsilon confirmed that these isoforms translocated to the forming phagosome in Ca-replete cells, but only PKC epsilon colocalized with phagosomes in Ca2+-depleted cells. Taken together, these results suggest that the classic PKC alpha mediates IgG-stimulated respiratory burst in macrophages, whereas the novel PKCs delta and/or epsilon are necessary for phagocytosis.

Differential markers for regionalization

OBJECTIVE

To examine the site of delivery for very low birth weight (VLBW) infants and infants with major congenital malformations (MCM) within an established system of perinatal regionalization.

STUDY DESIGN

A retrospective study of site of delivery for VLBW infants and infants born with MCM (tracheoesophageal fistula/esophageal atresia, diaphragmatic hernia, or gastroschisis/omphalocele) from 1990 through 1995 in Ohio.

RESULTS

A total of 59.8% of VLBW infants and 36.1% of MCM infants were born in a level III hospital. There was a significant trend toward a decrease in VLBW infants (p < 0.01) and an increase in MCM infants (p < 0.05) born in a level III hospital between 1990 and 1995. There were significant regional variations among the six perinatal regions in Ohio in the proportion of both VLBW and MCM infants born in a tertiary center.

CONCLUSION

Using the traditional marker of VLBW to assess regionalization in one state, we found significant variation in site of delivery among the perinatal regions and over the time course of the study. The delivery of infants with MCM at level III centers may be an alternative measure of regionalization.

Prolonged cyclooxygenase-2 induction in neurons and glia following traumatic brain injury in the rat

Cyclooxygenase-2 (COX2) is a primary inflammatory mediator that converts arachidonic acid into precursors of vasoactive prostaglandins, producing reactive oxygen species in the process. Under normal conditions COX2 is not detectable, except at low abundance in the brain. This study demonstrates a distinctive pattern of COX2 increases in the brain over time following traumatic brain injury (TBI). Quantitative lysate ribonuclease protection assays indicate acute and sustained increases in COX2 mRNA in two rat models of TBI. In the lateral fluid percussion model, COX2 mRNA is significantly elevated (>twofold, p < 0.05, Dunnett) at 1 day postinjury in the injured cortex and bilaterally in the hippocampus, compared to sham-injured controls. In the lateral cortical impact model (LCI), COX2 mRNA peaks around 6 h postinjury in the ipsilateral cerebral cortex (fivefold induction, p < 0.05, Dunnett) and in the ipsilateral and contralateral hippocampus (two- and six-fold induction, respectively, p < 0.05, Dunnett). Increases are sustained out to 3 days postinjury in the injured cortex in both models. Further analyses use the LCI model to evaluate COX2 induction. Immunoblot analyses confirm increased levels of COX2 protein in the cortex and hippocampus. Profound increases in COX2 protein are observed in the cortex at 1-3 days, that return to sham levels by 7 days postinjury (p < 0.05, Dunnett). The cellular pattern of COX2 induction following TBI has been characterized using immunohistochemistry. COX2-immunoreactivity (-ir) rises acutely (cell numbers and intensity) and remains elevated for several days following TBI. Increases in COX2-ir colocalize with neurons (MAP2-ir) and glia (GFAP-ir). Increases in COX2-ir are observed in cerebral cortex and hippocampus, ipsilateral and contralateral to injury as early as 2 h postinjury. Neurons in the ipsilateral parietal, perirhinal and piriform cortex become intensely COX2-ir from 2 h to at least 3 days postinjury. In agreement with the mRNA and immunoblot results, COX2-ir appears greatest in the contralateral hippocampus. Hippocampal COX2-ir progresses from the pyramidal cell layer of the CA1 and CA2 region at 2 h, to the CA3 pyramidal cells and dentate polymorphic and granule cell layers by 24 h postinjury. These increases are distinct from those observed following inflammatory challenge, and correspond to brain areas previously identified with the neurological and cognitive deficits associated with TBI. While COX2 induction following TBI may result in selective beneficial responses, chronic COX2 production may contribute to free radical mediated cellular damage, vascular dysfunction, and alterations in cellular metabolism. These may cause secondary injuries to the brain that promote neuropathology and worsen behavioral outcome.