Effect of fibrinogenolytic products D and E on fibrinogen and albumin synthesis in the rat.

Previous studies are in conflict over the effect of infusing mixed fibrinogen-fibrin degradation products on fibrinogen synthesis, as determined by changes in fibrinogen concentration or by incorporation of labeled amino acids into fibrinogen. We have injected purified homologous fragments D1 and E into rats and measured their fibrinogen and albumin synthetic rates by the [14C]carbonate technique, a method that provides quantitative estimates of hepatic secretory protein synthesis. Fibrinogen fractional synthetic rates were increased 2.5 times in animals injected with fragment D1, compared with saline-injected controls. No increase were observed in fragment E-injected animals. Neither fragment produced changes in albumin synthesis. Fragment D increased plasma fibrinogen concentration, but did not raise plasma haptoglobin levels. These results suggest that fragment D is a regulator of fibrinogen synthesis.

Comparison of procoagulant activities in extracts of normal and malignant human tissue.

Cancer procoagulant A (CPA) was originally described in extracts of tumor tissue, but whether this represented a quantitative and/or a qualitative difference from procoagulant activity in normal tissue extracts was not clear. Procoagulant activity was quantitated in extracts of 12 matched normal and malignant human tissue samples from the large intestine, breast, lung, and kidney. The specific activity of procoagulants in the tumor extracts was not greater than that in the extracts of normal tissue. Two enzymatic characteristics of CPA that distinguish it from tissue thromboplastin are its inhibition by diisopropylfluorophosphate (DFP) and its lack of dependence on factor VII. These specific tests were used to evaluate qualitative differences between procoagulants from normal and malignant intestinal tissues. In the paired normal and malignant tissue extracts, all tumor samples were inhibited by DFP and were active in factor VII-depleted bovine plasma (F7D-BP). In contrast, the extracts of normal tissue were insensitive to DFP and, except for one extract, were inactive in F7D-BP. Four of 9 other tumor extracts (44%) were positive for both of these tests for CPA, whereas the other 5 extracts were positive for only one of the two tests. The results suggest that extracts of normal and malignant tissues contained similar levels of procoagulant. However, malignant tissue contained a procoagulant enzymatically different from normal tissue thromboplastin. Furthermore, most of the malignant tissue extracts seemed to contain little or no thromboplastin.

Differences in judgments of learning difficulty.

Academically successful and less successful fifth graders were asked to make judgments about the ease of understanding and remembering various sentences and were given the opportunity to attempt to remember some of them before being asked to judge new sets of sentences. The results of the first experiment indicate that, at the beginning of the experiment, the successful students were much more likely than their less successful peers to realize that sentences expressing arbitrary relationships were more difficult to remember. These differences became even greater after students were given the opportunity to attempt to remember some of the sentences they had judged initially. The memory performance of the successful students also improved as they became more familiar with the experimental task, but the performance of the less successful students did not. The results of the second experiment showed that less successful students who had received appropriate training were able to use information about the arbitrariness of relationships as the basis for their judgments of learning difficulty. The training also facilitated their ability to remember. Implications of these findings are discussed.

Marrow biopsy and survival in multiple myeloma.

Pretreatment posterior iliac crest bone marrow biopsies were obtained from 26 multiple myeloma patients. Biopsies were processed in methacrylate. The percentage of myeloma tissue, myeloid tissue, and fat was estimated in each biopsy. In 20 patients who died there was a positive correlation between the percent of myeloid tissue in posterior iliac crest biopsies and survival time (r = 0.47, P less than 0.025), but no correlation could be demonstrated between percentage of myeloma tissue and survival time. The ratio of percentage of myeloid tissue to percentage of myeloma tissue also was related to survival. Six deceased patients with ratios greater than one had a median survival of 4.4 years, compared with 1.8 years in 12 deceased patients with ratios less than one. These medians differ significantly (P less than 0.05). Seven patients also had simultaneous biopsies of the posterior iliac crest and either or both the greater trochanter and the proximal tibia. All five greater trochanter biopsies showed extension of both myeloma tissue and myeloid tissue into the proximal appendicular skeleton.

Halothane-induced alteration in the fluidity of rat brain synaptosomal membranes and its relationship to anesthesia.

Concentrations of halothane 1.43% or higher abolished the pain response and induced anesthesia. Halothane increased membrane fluidity of synaptosomes and microsomes both at non-anesthetic and anesthetic concentrations. Changes in fluidity in synaptosomes did not return to control levels even after the animals recovered from anesthesia. Alteration in membrane fluidity by halothane is a non-selective effect and may not play a definitive role in anesthesia.

Fibrin- and fibrinogen-related antigens in patients with venous disease and venous ulceration.

Abnormalities in systemic fibrinolysis have been implicated in the pathogenesis of venous ulceration. Patients with venous disease have a prolonged euglobulin lysis time and elevated plasma fibrinogen levels, yet little is known about the metabolism of fibrinogen and fibrin in such patients. In this study, we have used a technique that involves electrophoresis and densitometric analysis of captured fibrin-related antigens to measure the concentration and proportions of the individual fibrin and fibrinogen degradation products in patients with venous disease of the lower extremity. As a group, patients with venous disease had markedly elevated levels of total fibrin-related antigen and D-dimer, the terminal degradation product of cross-linked fibrin. Levels of D-monomer, the breakdown product of fibrinogen and non-cross-linked fibrin monomer, and a measure of fibrinogenolysis were normal in all patients. In patients with ulcers, the levels of D-dimer were disproportionately higher than expected from fibrin monomer levels. On an individual basis, significant elevations of D-dimer were present in six (55%) of the 11 patients with venous disease with ulcers and in three (43%) of the seven patients with venous disease without ulcers. We conclude that patients with venous disease have uniform evidence for enhanced fibrin formation, as evidenced by elevated levels of total fibrin-related antigen and D-dimer. This is regardless of whether the venous disease is accompanied by ulceration.

Halothane alters electrical activity and calcium dynamics in cultured mouse cortical, spinal cord, and dorsal root ganglion neurons.

Halothane inhibits neural plasma membrane Ca(2+)-ATPase, a pump that ejects Ca2+ from the cell after influx through voltage- or ligand-activated channels. Intracellular microelectrode recordings in mouse embryonic cortical and spinal cord neurons showed that halothane and eosin, a pump inhibitor, prolonged repolarization associated with spontaneous bursts of depolarization. These agents also prolonged the repolarization phases of electrically induced action potentials and of capsaicin-mediated Ca(2+)-dependent depolarization in mouse adult dorsal root ganglion neurons. In keeping with these findings, confocal microfluorimetry showed that halothane delayed clearance of intracellular Ca2+ accumulated by N-methyl-D-aspartate stimulation of single neurons.

Alcohol pretreatment alters the metabolic pattern and accelerates cocaine metabolism in pigs.

We investigated whether alcohol pretreatment would affect the disposition and metabolic pattern of intravenously (i.v.) administered cocaine in pigs. Six pigs (Group A) received alcohol (1 g/kg/day) and six pigs (control; Group D) received an equal volume of isocaloric dextrose 44% in water for 10 days via an intragastric tube. On day 11, arterial samples were taken for five hours following an intravenous administration of cocaine hydrochloride (4 mg/kg). Plasma concentrations of cocaine and its major metabolites were analyzed by HPLC method. Significant decrease in plasma half-life (10 +/- 1.2 vs. 18.7 +/- 1.4 min), and significant increases in apparent volume of distribution (73 +/- 6 vs. 51 +/- 31) and clearance (5.37 +/- 0.6 vs. 1.82 +/- 0.1 l/min) were seen in alcohol pretreated pigs as compared with control pigs (P < 0.05). Significant increases in plasma concentrations of benzoylecgonine (P < 0.05), and insignificant differences in ecgonine methyl ester and norcocaine levels were seen between the two groups. Neither ecgonine nor cocaethylene was detected in the blood samples. Our data show that alcohol administration for ten days accelerated the elimination of i.v. administered cocaine and altered its metabolic pattern in pigs.

Diminished brain synaptic plasma membrane Ca(2+)-ATPase activity in spontaneously hypertensive rats: association with reduced anesthetic requirements.

We have recently reported that plasma membrane Ca(2+)-ATPase (PMCA) pumping activity in rat brain synaptic plasma membranes (SPM) was reduced by in vitro or prior in vivo exposure to inhalation anesthetics (IA). In addition, rats with streptozocin-induced diabetes were found to have diminished brain synaptic PMCA pumping and a decrease in the partial pressures of several IA required to prevent movement in response to stimulation, defined as the minimum effective dose or MED. Diminished PMCA activity in erythrocytes of spontaneously hypertensive rats (SHR) has been noted. Because PMCA is ubiquitous, it seemed possible that PMCA pumping might be decreased in the brain of SHR and perhaps associated with decreased IA requirement. Eighteen SHR and 18 control, normotensive Wistar-Kyoto rats (WKY) were studied. PMCA activity was assessed by measurement of Ca2+ uptake into synaptic plasma membrane vesicles prepared from cerebrum and diencephalon-mesencephalon (D-M) in WKY and SHR. Ca2+ pumping was significantly less in SHR than in WKY, 85% of control in the cerebrum and 90% in the D-M (p < 0.01). The MEDs for halothane, isoflurane and desflurane were also lower in SHR than in WKY, 91%, 90% and 89%, respectively, of control (p < 0.05). Thus, an animal model of primary hypertension (SHR) manifested diminished brain synaptic PMCA activity and reduced MED for several volatile anesthetics. These findings provide further evidence for a role for PMCA in anesthetic action.

Nitrous oxide and xenon enhance phospholipid-N-methylation in rat brain synaptic plasma membranes.

Halothane and isoflurane increase the rate of phospholipid methylation (PLM) in rat brain synaptosomal membranes, a process linked to the coupling of neuronal excitation to neurotransmitter release. In contrast, synaptic plasma membrane (SPM) Ca2+ ATPase (PMCA) pumping is reduced by exposure to halothane, isoflurane, xenon and nitrous oxide (N2O). To examine further the relationship between PLM, PMCA and anesthetic action, we investigated the effect of clinically relevant concentrations of two less potent anesthetic gases, N2O and xenon, on PLM in SPM. Biochemical assays were performed on SPM exposed to 1.3 MAC of N2O (2 atm), 1.3 MAC of xenon (1.23 atm) or an equivalent pressure of helium for control. N2O or xenon exposure increased PLM to 115% or 113%, respectively, of helium control (p < 0.02). Similar exposures to N2O or xenon depressed PMCA activity to 78% and 85% of control (p < 0.05). Observations that PLM and PMCA are both altered by a wide variety of inhalation anesthetic agents at clinically relevant partial pressures lend support to a possible involvement and interaction of these processes in anesthetic action.