Kinetic characterization of hexokinase isoenzymes from glioma cells: implications for FDG imaging of human brain tumors

Quantitative imaging of glucose metabolism of human brain tumors with PET utilizes 2-[(18)F]-fluorodeoxy-D-glucose (FDG) and a conversion factor called the lumped constant (LC), which relates the metabolic rate of FDG to glucose. Since tumors have greater uptake of FDG than would be predicted by the metabolism of native glucose, the characteristic of tumors that governs the uptake of FDG must be part of the LC. The LC is chiefly determined by the phosphorylation ratio (PR), which is comprised of the kinetic parameters (Km and Vmax) of hexokinase (HK) for glucose as well as for FDG (LC proportional to (Km(glc) x Vmax(FDG))/(Km(FDG) x Vmax(glc)). The value of the LC has been estimated from imaging studies, but not validated in vitro from HK kinetic parameters. In this study we measured the kinetic constants of bovine and 36B-10 rat glioma HK I (predominant in normal brain) and 36B-10 glioma HK II (increased in brain tumors) for the hexose substrates glucose, 2-deoxy-D-glucose (2DG) and FDG. Our principal results show that the KmGlc < KmFDG < Km2DG and that PR2DG < PRFDG. The FDG LC calculated from our kinetic parameters for normal brain, possessing predominantly HK I, would be higher than the normal brain LC predicted from animal studies using 2DG or human PET studies using FDG or 2DG. These results also suggest that a shift from HK I to HK II, which has been observed to increase in brain tumors, would have little effect on the value of the tumor LC.     

Functional conservation of the polysaccharide biosynthetic protein WbpM and its homologues in Pseudomonas aeruginosa and other medically significant bacteria

WbpM is a highly conserved protein involved in synthesis of the O antigens of Pseudomonas aeruginosa. Homologues of this protein have been identified in a large number of bacteria, and they can be divided into two subfamilies: subfamily 1, including WbpM, contains large proteins ( approximately 600 amino acids), while subfamily 2, typified by HP0840 (FlaA1) of Helicobacter pylori, contains smaller proteins ( approximately 350 amino acids) homologous to the C termini of proteins in subfamily 1. Analysis of knockout mutants of wbpM in P. aeruginosa serotypes O3, O10, O15, and O17 showed that although all 20 serotypes of P. aeruginosa possess wbpM, it is not universally required for O-antigen biosynthesis. Homologous genes from Bordetella pertussis (wlbL), Staphylococcus aureus (cap8D), and H. pylori (flaA1) complemented a P. aeruginosa O5 wbpM mutant to various degrees. These conserved proteins may represent interesting targets for the design of inhibitors of bacterial exopolysaccharide biosynthesis.     

Anatomy of pelvic arteries adjacent to the sacrospinous ligament: importance of the coccygeal branch of the inferior gluteal artery

OBJECTIVE: To examine the risk factors and pregnancy outcomes associated with 53 cases of amniotic fluid embolism that occurred in California during the 2-year period January 1, 1994 to December 31, 1995. METHODS: Data were obtained from a computerized database that contains linked records from the vital statistics birth certificate and hospital discharge summaries of both mother and newborn. This database covered all singleton deliveries that occurred in 328 civilian acute-care hospitals in California, which represented 98% of all deliveries in California. All cases of amniotic fluid embolism were examined for other pregnancy complications. RESULTS: There were 1,094,248 deliveries during that 2-year period. Fifty-three singleton gestations had the diagnosis of amniotic fluid embolism, for a population frequency of one per 20,646 deliveries. Fourteen women with amniotic fluid embolism died, for a maternal mortality rate of 26.4%. There were 35 (66%) diagnoses of disseminated intravascular coagulation (DIC), 38 (72%) diagnoses of hemorrhage, and 25 (47%) diagnoses of obstetric shock. Among the 14 women who died, the frequency of DIC (79%) and hemorrhage (71%) was not different compared with that of the survivors (62% and 72%, respectively), but obstetric shock was higher (86%, P = .02) than in survivors (33%). The average maternal length of stay for survivors was 6.5 days (range 3-27 days, median 5 days). The cesarean rate was 60% and the frequency of fetal distress was 49%. CONCLUSION: In this population-based study of reported cases of amniotic fluid embolism, the maternal mortality rate (26.4%) was significantly less than previously reported and might reflect a more accurate population frequency. In addition, patients who survived and patients who died had similar pregnancy complications, suggesting that amniotic fluid embolism was present in all cases and not limited to those who died.     

Induction of melanoma-associated antigen systemic immunity upon intratumoral delivery of interferon-gamma retroviral vector in melanoma patients

A total of 17 patients with metastatic melanoma were treated with intratumoral interferon-gamma (IFN-gamma) retroviral vector in a phase I clinical trial. A cycle of treatment consisted of five daily injections every 2 weeks. Patients were divided into two treatment arms that involved a single course (one cycle) of treatment (group I; n = 9) and multiple cycles (six cycles) of treatment (group II; n = 8). Patients received intratumoral injections of IFN-gamma (10(7) plaque-forming units/mL administered at 0.3, 0.5, and 1.0 mL per cohort of patients). All patients receiving multiple injections either maintained stable disease (n = 5) or achieved a partial or complete response (n = 3) of the injected lesion, whereas in patients receiving a single cycle of treatment, only one of nine patients had a response. Patients were assessed for immunoglobulin G antibody (Ab) responses to the melanoma-associated antigens (MAA) tyrosinase, gp100, TRP-2, and MAGE-A1 by affinity enzyme-linked immunosorbent assay. Anti-MAGE-A1 and tyrosinase Ab were significantly elevated from baseline (day 0) to week 16 during treatment (P = .005; P = .002, respectively) in patients who received multiple injections. Patients undergoing treatment who had a clinical response (stable disease or better) also had significantly more elevated Ab responses to a greater number of MAA (P = .0004). The induction of systemic Ab responses to multiple MAA also correlated with systemic clinical responses. These studies suggest that multiple anti-MAA Ab responses are associated with clinical responses to IFN-gamma retroviral treatment and may be used as surrogate response markers.     

Colon cancer incidence among modelmakers and patternmakers in the automobile manufacturing industry. A continuing dilemma

Modelmakers and patternmakers in an automobile manufacturing corporation located in the Detroit metropolitan area expressed concern about cancer incidence in their work group. In particular, previous studies among woodworking patternmakers and modelmakers employed in the automobile manufacturing industry found excesses in the incidence of cancers of the colon and rectum. To determine cancer incidence among the study corporation's woodworkers, a computerized record linkage study was performed. Cancer incidence data from the Michigan Cancer Foundation Division of Epidemiology's Metropolitan Detroit Cancer Surveillance System (MDCSS) were linked with corporate records for their woodworkers. In this group of 316 workers, ten cancers were found, four of which were colon cancers. A standard morbidity ratio analysis revealed a statistically significant excess of colon cancer in the woodworkers, compared with a general population group matched for race, gender and age (SMR = 487.0, p less than .01). These results are consistent with observations made in previous studies. The question raised by these findings is whether an occupational exposure contributes to this excess occurrence of colon cancers or whether these groups share some other common attributes, such as dietary habits.