A novel peptide motif for platelet fibrinogen receptor recognition

To develop a specific antagonist of platelet alphaIIbbeta3 using small linear peptides, we synthesized a series of hexapeptides that did not have an Arg-Gly-Asp (RGD) sequence and examined their anti-platelet activity and their specificity for alphaIIbbeta3. We found a novel motif sequence, Pro-X1-X2-X3-Asp-X4, where X1 to X4 were all L-form alpha-amino acids, which specifically inhibited aggregation of human platelets at submicromolar concentrations. The Pro residue at the N terminus was essential to the anti-platelet activity, and the acetylation of the imino group of this residue also resulted in the complete loss of the activity. The results of the binding assay using purified human platelet alphaIIbbeta3 and placental alphavbeta3 and those of the cell adhesion assay suggest that this motif peptide is highly specific for platelet alphaIIbbeta3 among other integrins. Flow cytometric studies using an fluorescein isothiocyanate-labeled RGD peptide showed that this motif peptide inhibited the binding of an RGD peptide to activated platelets, suggesting that it has the same inhibitory mode as RGD peptides. Conformational analysis of this motif peptide and an RGD-containing peptide suggests that the imino group of the Pro residue may substitute for the role of the guanidino group of the Arg residue of the RGD sequence.

Phased chest and abdominal compression-decompression. A new option for cardiopulmonary resuscitation

BACKGROUND

We describe a new manual method of phased chest and abdominal compression-decompression with a Lifestick resuscitator for cardiopulmonary resuscitation (CPR).

METHODS AND RESULTS

Ventricular fibrillation (VF) was induced in 20 domestic pigs. After either 5 or 7 minutes of untreated VF, either phased chest and abdominal compression-decompression (Lifestick resuscitator) or precordial compression was initiated. Defibrillation was attempted at 2 minutes after the start of CPR. For the animals in which VF was untreated for 7 minutes, epinephrine was administered in doses of 20 micrograms/kg at 2 minutes after start of CPR. The coronary perfusion pressure generated by the Lifestick resuscitator was more than twofold greater (P < .01) than that generated by conventional precordial compression. Of 5 control animals, none were resuscitated after 5 minutes of VF. However, each of 5 animals treated with the Lifestick resuscitator was resuscitated (P < .01) and survived after 48 hours (P < .01). When untreated VF was prolonged to 7 minutes and epinephrine was administered, only 2 of the 5 control animals were resuscitated, and none of them survived for more than 4 hours. However, each of the Lifestick-treated animals was resuscitated and survived for more than 48 hours (P < .01).

CONCLUSIONS

Phased chest and abdominal compression-decompression substantially increased hemodynamic efficacy of CPR and outcome in terms of successful resuscitation, 48-hour survival, and cerebral recovery.

Characterization of an interleukin 1 receptor antagonist protein released from ultraviolet-irradiated epidermal sheet

An interleukin 1 (IL-1) inhibitor was detected in the culture supernatant of mouse epidermal sheet which had been irradiated with middle-wavelength ultraviolet (UVB) either in vitro or in vivo. Properties of the IL-1 inhibitor were consistent with those of IL-1 receptor antagonist (IL-1ra), i.e., approximate molecular size of 17 kDa by gel filtration, specific inhibition of IL-1-induced thymocyte proliferation, inhibition of binding of IL-1 to IL-1 receptor on the T-cell surface, and reactivity to anti-mouse IL-1ra antibody shown by immunoblotting and enzyme-linked immunosorbent assay (ELISA). These results indicate that this IL-1 inhibitor, which appears to be identical with IL-1ra, was released from the epidermis upon UVB irradiation, and that the inhibitor may participate in the regulation of inflammation mediated by IL-1, as well as in the pathogenesis of ultraviolet (UV)-induced immunosuppression.

SPECT with In-111 autologous platelets to detect residual splenic tissue in two patients with relapsed thrombocytopenia

In two patients with relapsed thrombocytopenia, the authors used SPECT with In-111 labeled autologous platelets to identify residual splenic tissue after splenectomy. One case involved a previously splenectomized patient with idiopathic portal hypertension, while the other had relapsed chronic idiopathic thrombocytopenic purpura (ITP). In both patients, SPECT showed a higher In-111 uptake in the splenic tissues compared with planar images. In the patient with ITP, a small accessory spleen had been overlooked on abdominal CT because of post-operative changes, but it was identified by superimposition of SPECT/CT images. These cases indicate that In-111 platelet SPECT is useful in detecting and localizing residual accessory splenic tissue associated with relapsed thrombocytopenia.

[An experience with omentopexy for the repair of postoperative bronchopleural fistula]

Postoperative bronchopleural fistula has been the most troublesome complications in the thoracic surgery. In this report, we presented a case of bronchopleural fistula successfully closed by omentopexy. A 51-year-old man had undergone left upper lobectomy and S6 segmentectomy for primary lung cancer. Bronchopleural fistula due to postoperative pneumonia was developed and completion pneumonectomy with the intercostal-musclo-pexy was performed. Post-re-operative course was unsuccessful, bronchopleural fistula remained, so we tried re-closure of the bronchial stump by omentopexy without thoracoplasty or muscle flap plombage. About a half year after 3rd operation, he relapsed into bronchopleural fistula. Then fibrin gluing was performed via a flexible fiberoptic bronchoscope without hospitalization, and the omental flap was fixed completely to the bronchial stump. We believe the omentopexy a useful procedure for treating postoperative bronchopleural fistula which can't make any chest-wall deformation.

[Potency of CPR without artificial breathing]

Recent experimental studies reported by several independent groups demonstrated that in the initial interventions of cardiopulmonary resuscitation (CPR), airway protection (A) and artificial breathing (B) are not essential for successful recovery from cardiac arrest. In this study, we reviewed and compared those reports to investigate individual effects of A and B on initial CPR. Airway protection: Spontaneous gasping during cardiac arrest is accompanied by upper airway protective reflexes such as head tilt and open mouth. Gasping promoted CO2 elimination from the nose in animals without A. Breathing: Gasping and precordial compression generated ventilation up to 150 and 100 ml.kg-1. min-1 respectively during cardiac arrest. Arterial blood gas analyses demonstrated that CPR without B developed hypercarbia, but maintained oxygen tensions in physiological levels. The frequency of chest compression is in the range of high frequency ventilation, which might allow for successful oxygenation regardless of limited tidal volumes. A series of experimental studies for CPR without A or B call for establishment of a simple CPR method for bystanders, namely "Just compress the chest".

Genetic diversity of the genes encoding the outer membrane lipoprotein (omlA) of Actinobacillus pleuropneumoniae

An allelic variation of the genes encoding the protective outer membrane lipoprotein (omlA) in Actinobacillus pleuropneumoniae was investigated with polymerase chain reaction (PCR)-restriction fragment length polymorphisms. Primers for PCR were selected from a conserved sequence compared between the omlA genes of A. pleuropneumoniae serotypes 1 and 5a. A DNA fragment of 970 bp was amplified from the genomic DNA of all 12 serotypes of A. pleuropneumoniae. The amplified DNA sequence specifically hybridized under a low stringent condition to the cloned omlA gene of A. pleuropneumoniae. Digestion of the amplified DNA with the enzymes either HinfI or VspI yielded specific polymorphic patterns, allowing discrimination of all serotypes into five distinct groups.

Glutathione status and reactive oxygen generation in tissues of young and old exercised rats

The effects of exercise on the generation of active oxygen species and radical-scavenging capacity were studied in physically active and sedentary young and old rats. Exercise increased the hydroxyl radical content in all tissues of physically active young rats, except in the plasma. In old rats, the basal level of the radical increased significantly in plasma, heart, and skeletal muscles, but decreased in liver; and physical activity decreased it to that of young rats in most cases. With exercise, the content of reduced glutathione increased in plasma, heart, and skeletal muscles of young rats, whereas that of oxidized glutathione markedly decreased in liver and increased in brain and white gastrocnemius muscle. The total glutathione levels in these tissues changed in a similar way, indicating that glutathione was released from the pool in the liver. In rats allowed to run voluntarily for 5 weeks, the effects were more pronounced than in the sedentary rats. The ratio of reduced to total glutathione, which indicates the capacity to reduce glutathione, increased in plasma, heart, and soleus muscle of sedentary young rats after exercise, and increased further in those undergoing physical activity. In old rats, the reduced glutathione level increased in plasma, heart, liver, and brain, even though the total decreased. These results suggest that physical activity enhances the endogenous ability to defend against oxidative stress. In old rats, even though glutathione synthesis is decreased, the regenerating capacity seems to be increased in order to compensate for the increased oxidative stress.

An early insulin intervention accelerates pancreatic beta-cell dysfunction in young Goto-Kakizaki rats, a model of naturally occurring noninsulin-dependent diabetes

This study was designed to delineate the nature of beta-cell dysfunction in a model of genetically determined nonobese diabetes, the Goto-Kakizaki (GK) rat. Pancreatic beta-cell function was analyzed immediately after weaning and 5 weeks thereafter, comparing animals with or without insulin treatment during the interval. In 3.5-week-old GK rats, fasting plasma glucose was mildly elevated with normoinsulinemia, and the islet insulin content was reduced by 33%. When incubated with 3-30 mM glucose in vitro, the GK rat islets showed reduced glucose sensitivity, i.e. the EC50 values were 19.5 and 15.9 mM, and the Hill constants for the positive cooperativity 2.1 and 4.2 in the islets of GK and the control rats, respectively. On the other hand, the maximum response to glucose was not attenuated when reduced islet insulin content was considered. In 8.5-week-old GK rats hyperglycemia worsened and glucose-stimulated insulin release by the islets more severely impaired. A daily insulin injection from the 3.5-8.5 weeks of age significantly lowered plasma glucose in the GK rat, accompanied by a marked suppression of both basal (with 3 mM glucose) and glucose (6-30 mM)-stimulated insulin release by the islets. In the GK rat, beta-cell dysfunction develops by the age of 3.5 weeks, and insulin treatment during the subsequent 5 weeks accelerates its progression.

Regional differences in the depressant effects of midazolam on excitatory synaptic transmission in the rat hippocampus

The effects of midazolam, one of the most popular benzodiazepines, was examined on excitatory synaptic transmission in the hippocampus. Both CA1 pyramidal cells (CA1-PCs) and dentate gyrus granule cells (DG-GCs) were studied in rat hippocampal slices with extracellular recordings. Midazolam depressed the amplitudes of orthodromic population spikes (O-PS) and excitatory postsynaptic potential (EPSP) slopes of CA1-PCs in a dose-dependent manner, but depressed those of DG-GCs to a lesser extent. On the other hand, midazolam had little effect on the amplitudes of antidromic population spikes of both CA1-PCs and DG-GCs. A GABAA receptor antagonist bicuculline strongly antagonized the depressant effects of 75 microM midazolam on the amplitudes of O-PS by 73% in CA1-PCs, whereas it did not antagonize the effects of midazolam in DG-GCs. These results suggest that the differential effects of midazolam could be due to the different types and/or density of GABAA receptors between CA1-PCs and DG-GCs.

Recurrence of spontaneous intracranial hypotension with subdural hematomas

A 59-year-old man developed postural headache associated with a low CSF pressure. A CT scan revealed no abnormal findings and the orthostatic symptoms resolved without treatment 6 weeks after onset. He was diagnosed as having spontaneous intracranial hypotension (SIH) and remained symptom-free until he experienced recurrence of postural headache 9 months later. A lumbar puncture demonstrated low CSF pressure, and a CT scan revealed slit-like ventricles with narrowing of the sulci, Sylvian fissures, and infratentorial cisterns, in addition to bilateral subdural masses. After draining the hematomas, his symptoms resolved completely, and a follow-up CT scan was normal. We hypothesize that recurrent SIH in this case was due to small recurrent tears of a root sleeve. This case emphasizes the importance of follow-up of SIH for at least 9 months after resolution of symptoms.

beta-Adrenergic regulation of cAMP and protein phosphorylation in phospholamban-knockout mouse hearts

The stimulatory effects of beta-adrenergic agonists reflect increases in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels and phosphorylation of key regulatory proteins in the heart. One of these phosphoproteins is phospholamban (PLB) in sarcoplasmic reticulum, and ablation of PLB is associated with attenuation of the contractile responses to beta-adrenergic stimulation in the mouse heart. To determine whether this attenuation of beta-stimulation is due to altered phosphorylation characteristics of the other key cardiac phosphoproteins and/or to compensatory responses occurring in the absence of PLB, PLB-knockout and wild-type hearts were perfused and their protein phosphorylation patterns examined. The beta-adrenergic receptor density, adenylyl cyclase activity, tissue cAMP levels, and the basal phosphoprotein pattern were similar between PLB-knockout and wild-type hearts. Isoproterenol perfusion resulted in similar increases in the tissue cAMP levels and the degree of phosphorylation of troponin I, C protein, and the 21-kDa microsomal protein in wild-type and PLB-knockout hearts. These findings indicate that the attenuation of isoproterenol-mediated increases in contractility of the PLB-knockout hearts is not due to alterations in the beta-adrenergic signal transduction pathway or the degree of phosphorylation of the key cardiac regulatory phosphoproteins in myofibrils and sarcolemma.

Strengthening routine immunization services in the Western Pacific through the eradication of poliomyelitis

Infant immunization coverage in the Western Pacific Region of the World Health Organization was reviewed to evaluate the impact of polio eradication activities on routine immunization services. The trend in bacille Calmette-Guérin (one dose; BCG), diphtheria-tetanus toxoids-pertussis (three doses; DTP3), and measles (one dose) vaccination rates was analyzed from the beginning of eradication activities in 1990 to 1994 in the five polio-endemic countries that conducted supplementary oral polio vaccine immunization. In China and the Philippines, coverage for each antigen remained at or above 90% and 85%, respectively, while in Vietnam, coverage for all three antigens rose from 85% to 95%. BCG, DTP3, and measles vaccine coverage more than doubled in the People's Democratic Republic of Lao and increased by >30% in the Kingdom of Cambodia during the same period.

Development and coordination of the Polio Laboratory Network in the Western Pacific Region of the World Health Organization

A multitiered network of polio laboratories, consisting of specialized reference laboratories, regional reference laboratories, national laboratories and, in the case of China, provincial laboratories, was established in the Western Pacific Region of the World Health Organization (WHO) in 1992. The network currently consists of 43 laboratories within the Region and is coordinated through the WHO Regional Office in Manila. As the levels and extent of supplementary immunization and acute flaccid paralysis surveillance activities have increased, so has the work load of network laboratories. The total number of stool specimens collected and processed in Polio Laboratory Network laboratories in this WHO region in 1995 exceeded 15,000. With the Region now establishing the criteria necessary for certification of polio-free status, it is essential for the Polio Laboratory Network to establish international confidence in its ability to carry out its role in the eradication of polio.

Decoy approach using RNA-DNA chimera oligonucleotides to inhibit the regulatory function of human immunodeficiency virus type 1 Rev protein

Human immunodeficiency virus type 1 (HIV-1) encodes two regulatory proteins, Tat and Rev, that bind to target RNA sequences. These are the trans-activation responsive (TAR) RNA and the Rev-responsive element (RRE), respectively. The Rev protein shifts RNA synthesis to viral transcripts by binding to the RRE within the env gene. In the present study we prepared a RNA-DNA chimera consisting of 29 or 31 nucleotides to inhibit the Rev regulatory function by means of the decoy approach. The chimera oligonucleotides (anti-Rev oligonucleotides [AROs]) contained an RNA "bubble" structure (13 oligonucleotides; the Rev-binding element in RRE) that bound Rev with a high affinity in an in vitro assay. The controls were RNA-DNA chimera oligonucleotides (negative control oligonucleotides [NCOs]) similar to ARO, but without the bubble structure, that bound with considerably less affinity to Rev. When the inhibitory effects of these decoys on HIV-1 replication were examined, we found that AROs, but no NCOs, reduced more than 90% of the HIV-1 production generated by productively infected human T-cell lines. The production of primary HIV-1 isolates in healthy donor-derived peripheral blood mononuclear cells was also similarly inhibited by AROs. In addition, the induction of viral mRNAs and antigens in latently HIV-1-infected ACH-2 cells by tumor necrosis factor alpha was specifically inhibited by AROs, but not by NCOs. No apparent cytotoxicity was caused by either decoy. Thus, the use of a Rev-binding element-based decoy, the RNA-DNA chimera oligonucleotide, may represent a safer approach to gene therapy for reducing the virus load in HIV-1-infected individuals.

Changes in the activity and mRNA of cinnamyl alcohol dehydrogenase during tracheary element differentiation in zinnia

Changes in the enzymatic activity of cinnamyl alcohol dehydrogenase (CAD) and in the expression of a gene for CAD during tracheary element (TE) differentiation were investigated in cultures of single cells isolated from the mesophyll of zinnia (Zinnia elegans). In cultures in which TE differentiation was induced (TE-inductive cultures), CAD activity increased from h 36 after the start of culture (12 h before the start of thickening of the secondary cell wall) and peaked at h 72, when lignin was actively being deposited. In control cultures in which TE differentiation was not induced, CAD activity remained at a very low level for 5 d. Some isoforms of CAD were detected only in the TE-inductive cultures by native gel electrophoresis and subsequent staining for CAD activity. A cDNA clone for CAD, ZCAD1, was isolated from Z. elegans using a cDNA clone for CAD from Aralia cordata as the probe. RNA gel-blot analysis revealed that in the TE-inductive cultures the level of ZCAD1 mRNA increased from h 36 and peaked at h 48 to 60. No such increases were observed in control cultures. These results indicated that both the gene expression and the activity of CAD are strictly regulated, in association with lignification, during TE differentiation in Z. elegans.

Test cell migration and tunic formation during post-hatching development of the larva of the ascidian, Ciona intestinalis

Morphological changes in the tunic layers and migration of the test cells during swimming period in the larva of the ascidian, Ciona intestinalis, were observed by light and electron microscopy. The swimming period was divided into three stages. In stage 1, further formation of juvenile tunic layer started only in the larval trunk and neck region. In stage 2, the layer became swollen in the ventral and dorsal sides of the neck region and in stage 3, the swelling expanded backward. Concomitantly with these changes, the outermost larval tunic layer (outer cuticular layer), which had been formed before hatching, also swelled in the neck region in stage 2 and formed two humps in stage 3, although the layer did not change in the tail region during the swimming period. Test cells that were present over the entire larval tunic layer in stage 1 began to move from the surface of the fin toward that of the side of the body in stage 2, and finally gathered to form six bands running radially from the anterior end to the posterior end of the trunk region and aligned along the lateral sides of body in the tail region in stage 3. In electron microscopic observations, pseudopodia protruding from the test cells invaded the larval tunic, following which they extended proximate to the juvenile tunic in the trunk region. In the tail region, which had no juvenile tunic layer as that described, the pseudopodia invaded and remained adjacent to the surface of the epidermis or the sensory cilia protruded from the epidermis. Metamorphosis of the larvae, further tunic formation, degradation of adhesive papilla, attachment of larva to the substratum and tail resorption commenced after these morphological changes occurred. The possible role of the test cells in metamorphosis is discussed.

Poliomyelitis eradication in the Western Pacific Region

Polio eradication activities in the Western Pacific Region (WPR) have reduced the transmission of wild poliovirus to one remaining focus of endemic transmission in the Mekong Delta area of South Vietnam and Cambodia. There has been a high level of government commitment for national immunization days in all WPR countries in which poliomyelitis was previously endemic and for continuous improvement in acute flaccid paralysis (AFP) surveillance quality. The total number of reported confirmed poliomyelitis cases in 1995 (as of June 1996) was 432, only 7% of the total of 5825 cases reported in 1990. In 1995, wild poliovirus was isolated from only 19 of 4800 AFP patients from whom specimens were collected and analyzed. There has been one importation of wild poliovirus type 1 into China from a neighboring country. An international Regional Commission for the Certification of Poliomyelitis Eradication in the WPR has been formed and met for the first time in April 1996.

The experience of countries in the Western Pacific Region in conducting national immunization days for poliomyelitis eradication

Experience with national immunization days (NIDs) in six countries of the Western Pacific Region has shown that political support at all levels, detailed logistics plans, strategies appropriate to the local situation, and simple social mobilization messages have been key factors in the success of NIDs. Conventional strategies that may apply to conducting routine Expanded Programme on Immunization vaccinations do not necessarily apply to NIDs, in which the maximum number of children must be immunized in 1 or 2 days. Setting up temporary immunization posts at sites convenient to the local situation, moving the posts once or twice during the course of a day, and using volunteers to staff them are among many of the adaptations used successfully. Coverage figures published immediately after an NID can be misleading because of uncertainty about the true denominator. The true measure of the success of NIDs is in surveillance for wild poliovirus after the event.

Synthesis of a new potent anti-angiogenic agent, 17 alpha-acetoxy-9 alpha-fluoro-6 alpha-methylprogesterone (9 alpha-fluoromedroxyprogesterone acetate [FMPA])

A new anti-angiogenic agent, 17 alpha-acetoxy-9 alpha-fluoro-6 alpha-methylprogesterone (9 alpha-fluoromedoroxyprogesterone acetate [FMPA, 9] was synthetized in a 10-step sequence. FMPA (9) had about two orders of magnitude stronger anti-angiogenic activity than medroxyprogesterone acetate (MPA), as estimated in a bioassay involving chorioallantoic membranes of growing chick embryos.

Two signaling pathways, from the upper glycolytic flux and from the mitochondria, converge to potentiate insulin release

In the rat pancreatic beta cell, low concentrations of glucose potentiate D-glyceraldehyde (GA)-induced insulin release without any potentiation of the triose-induced elevation of cytosolic free Ca2+ concentration. Namely, 2-3 mM glucose strongly potentiates 5 mM GA-induced insulin release, and the combination of stimulatory concentration of glucose (10 mM) and 5 mM GA elicits far more than additive insulin release: this glucose action is independent of ATP-sensitive K+ channel closure because it can be seen in the presence of diazoxide, an opener of the K+ channel. The triose-induced elevation of cytosolic free Ca2+ concentration was not potentiated by the presence of 3 mM glucose, and oxidation of labeled GA by the islet cells was not enhanced by the presence of glucose. The glucose action can be mimicked by mannose, but not by galactose, and was suppressed by inhibition of glucose phosphorylation with mannoheptulose or 2-deoxyglucose. Glucose also potentiates 2-ketoisocaproate-induced insulin release. In contrast, a combination of GA and 2-ketoisocaproate elicits only additive insulin release. Strikingly, 3 mM glucose does not potentiate insulin release in response to a depolarizing concentration of K+. Therefore, at least two signal pathways, one from upper glycolytic flux and one from mitochondrial metabolism, must converge to provide the potentiation of insulin release. We conclude that the upper glycolytic flux, acting at a site unrelated to the elevation of cytosolic free Ca2+, potentiates insulin release triggered by triose and mitochondrial fuels.

Cloning and sequence analysis of the gbpC gene encoding a novel glucan-binding protein of Streptococcus mutans

We have isolated dextran-aggregation-negative mutants of Streptococcus mutans following random mutagenesis with plasmid pVA891 clone banks. A chromosomal region responsible for this phenotype was characterized in one of the mutants. A 2.2-kb fragment from the region was cloned in Escherichia coli and sequenced. A gene specifying a putative protein of 583 amino acid residues with a calculated molecular weight of 63,478 was identified. The amino acid sequence deduced from the gene exhibited no similarity to the previously identified S. mutans 74-kDa glucan-binding protein or to glucan-binding domains of glucosyltransferases but exhibited similarity to surface protein antigen (Spa)-family proteins from streptococci. Extract from an E. coli clone of the gene exhibited glucan-binding activity. Therefore, the gene encoded a novel glucan-binding protein.

[Potential of photodynamic therapy with a second-generation sensitizer: mono-L-aspartyl chlorin e6]

We evaluated the potential for photodynamic therapy of a new photosensitizer, mono-L-aspartyl chlorin e6 (NPe6), whose tissue uptake and clearance are rapid. Firstly, NPe6 solution was exposed to a diode laser at 664 nm that fits the maximum absorption of NPe6. Immediately after laser exposure, the solution was subjected to electron spin resonance (ESR) to detect generation of activated oxygen species. With ESR, O2-, .OH, and 1O2 were detected in the NPe6 solution. O2- and .OH disappeared when superoxide dismutase was added to the solution. Next, the fundi of pigmented rabbits were irradiated with the diode laser after administration of NPe6. Histopathologically, there was necrosis of endothelial cells and vascular occlusion in the choroid, especially in the choriocapillaris. Retinal pigment epithelial cells were also injured. In contrast, the sensory retina was undamaged even after use of a large amount of dye. This new combination of NPe6 and diode laser at 664 nm enables us to occlude choroidal vessels efficiently by generating various activated oxygen species. Thus, photodynamic therapy with NPe6 is potentially useful in treating retinochoroidal involvement.

Esophageal PCO2 as a monitor of perfusion failure during hemorrhagic shock

Measurement of gastric wall PCO2 (PgCO2) by tonometric method has emerged as an attractive option for estimating visceral perfusion during circulatory shock. However, gastric acid secretion obfuscates the tonometric measurement. We, therefore, investigated the option of measuring PCO2 in the esophagus to minimize these restraints. Hemorrhagic shock was induced in five Sprague-Dawley rats, and five rats served as sham controls. PgCO2 was measured with an ion-sensitive field effect transistor that was surgically implanted into the gastric wall. Esophageal luminal PCO2 (PeCO2) was measured by a second ion-sensitive field effect transistor sensor. During hemorrhagic shock, mean aortic pressure declined from 150 to 50 mmHg. Gastric blood flow decreased from 58 to 12 ml.min-1.100 g-1 (21% of preshock) and esophageal blood flow from 44 to 7 ml.min-1.100 g-1 (16% of preshock). PgCO2 simultaneously increased from 47 to 116 Torr and PeCO2 from 47 to 127 Torr. The increases in PgCO2 were highly correlated with increases in PeCO2 (r = 0.90). Esophageal tonometry may, therefore, serve as a practical alternative to gastric tonometry.