Relationship between cardiac output and the end-tidal carbon dioxide tension

STUDY OBJECTIVE: To further define the relationship between cardiac output (CO) and end-tidal carbon dioxide tension (ETCO2) at various levels of systemic flow. DESIGN: Prospective, controlled laboratory investigation. SETTING: Animal laboratory. TYPE OF PARTICIPANTS: Fourteen anesthetized, intubated sheep weighing 23 to 47 kg. INTERVENTIONS: One hundred seventy-two simultaneous measurements of thermodilution CO and ETCO2 were made during controlled arterial hemorrhage. After a 30-minute baseline control period, CO was sampled from approximately 0.6 to more than 8.0 L/min during a 60- to 90-minute period of controlled hemorrhage. MEASUREMENTS: Thermodilution CO; arterial pressure using fluid-filled plastic 14-gauge catheters; ETCO2 using an infrared analyzer. MAIN RESULTS: A plot of CO versus ETCO2 suggested that the relationship was logarithmic rather than linear. Linear regression showed that ETCO2 was significantly related (r = .91; P less than .001) to a logarithmic transformation of the CO. CONCLUSIONS: The relationship between CO and ETCO2 is logarithmic. Decreased presentation of CO2 to the lungs is the major, rate-limiting determinant of the ETCO2 during low flow. As the CO increases during resuscitation from shock or cardiac arrest, respiration becomes the rate-limiting controller of the ETCO2 (after the tissue washout of CO2 has occurred). Under such conditions, the ETCO2 provides useful information about the adequacy of ventilation provided that there is little ventilation/perfusion mismatch.     

Unsuitability of monoclonal antibodies to oncogene proteins for anti-tumour drug-targeting

Monoclonal antibodies (MAbs) to ras, sis, erb-B, src, myb and myc oncoproteins were evaluated for their potential to target anti-cancer drugs to malignant cells. Each antibody was tested for reactivity against both fixed and viable cultured human tumour cells by immunofluorescence, and all reacted against a variety of fixed tumour cell preparations. Reactions were also observed against fixed non-malignant cells. None, however, reacted significantly with viable cells. Two antibodies (against ras and myc proteins) were tested for their ability to localize to tumour xenografts in nude mice, and conjugates were constructed by linking these antibodies to methotrexate using human serum albumin as an intermediate carrier. Neither antibody localized to tumour in vivo, and the methotrexate conjugates were not significantly cytotoxic for tumour cells in vitro, in contrast to similar conjugates simultaneously prepared with a proven anti-tumour MAb (791T/36). It was concluded that currently available MAbs to oncogene proteins are not suitable vectors for targeting cytotoxic agents to tumour cells.     

Measurement of tumour reactive antibody and antibody conjugate by competition, quantitated by flow cytofluorimetry

Binding of unlabelled monoclonal antibody preparations has been assessed by cometition at saturation with fluorochrome labelled homologous antibody for binding to antigen bearing target cells. The extent of competition was measured by quantitative flow cytofluorimetry, and simple mathematical procedures have been developed to allow the interpretation of competition data in terms of antibody binding activity. In the system studied, non-specific (non-competitive) fluorescence was minimal, but an iterative method to calculate its contribution to the measured signal is given. This approach has the advantage that the antibody preparation to be tested does not need to be labelled or modified; this is particularly important when evaluating the binding activity of therapeutic antibody conjugates. Comparison with a well characterized standard antibody preparation provides a rapid, sensitive and accurate quality control procedure. This test is also simple to perform, requiring only the mixing of labelled and unlabelled antibodies with target cells, a single incubation, followed by analysis without washing of the target cells.     

Further evidence for association of GRK3 to bipolar disorder suggests a second disease mutation

OBJECTIVES: Two genome-wide linkage surveys suggest chromosome 22q12 may contain a susceptibility locus for bipolar disorder (BPD) in the immediate region of the gene G protein receptor kinase-3 (GRK3). We previously published evidence that a single nucleotide polymorphism (SNP) in the promoter region of GRK3, designated P5, was associated with BPD. This SNP, however, was too rare (allele frequency 0.007) to explain the evidence for linkage. METHODS: To identify other SNPs or haplotypes associated with illness, we have now sequenced an additional 28-kb genomic segment of GRK3 and tested an additional 35 SNPs for association with BPD in 181 Caucasian nuclear families. RESULTS: Transmission disequilibrium test analyses identified two closely related disease-associated haplotypes defined by four SNPs located upstream of the promoter region: transmission to nontransmission ratios=54:22 and 20:9, odds ratios=2.50 and 2.36, and P values=0.0009 and 0.05. The best P value remained significant after correction for multiple testing. These two haplotypes were found on an entirely different set of chromosomes from the previously identified SNP P5. They had a combined frequency of approximately 0.10 and, therefore, a much greater population attributable risk for disease than the previously identified P5 haplotype. CONCLUSIONS: These data provide evidence that at least two distinct haplotypes, and possibly two or more different underlying mutations, in GRK3 might be associated with BPD. These new findings add support for the hypothesis that a dysregulation in GRK3 expression alters signaling desensitization and thereby predisposes to the development of BPD.     

Disposition of Misoprostol and Its Active Metabolite in Impaired Hepatic Function

The pharmacokinetics of misoprostol and its active metabolite, misoprostol acid, was assessed in 17 healthy subjects and 17 subjects with various degrees of hepatic impairment. Before misoprostol administration, subjects underwent antipyrine and indocyanine green clearance studies to assess hepatic functional capacity. Subjects were administered 400 mcg of oral misoprostol in an open-label design. There was a lower antipyrine clearance in the group with hepatic disease as compared to normal volunteers (0.56 versus 0.80 ml min(minus sign1) kg(minus sign1), respectively, p = 0.022). There was no difference in indocyanine green clearance values between groups. The C(max), t(1/2)&bgr, and [Formula: see text] tended to be larger in the hepatic group; however, there was no statistical difference. Adverse events, mostly gastrointestinal in nature, occurred more often in the subjects with hepatic disease. These data suggest the pharmacokinetics of misoprostol may be altered in the presence of hepatic disease. However, because of significant interpatient variability, definitive dosing recommendations cannot be made. Further study in this area is needed.