Comparison of the effect of carbon monoxide and of hypoxic hypoxia. I. In vivo metabolism, distribution and action of hexobarbital

1. The biosynthesis of cholesterol was studied, by using various precursors, in rats subjected to several dietary regimes. 2. The use of 3H2O as a substrate to demonstrate differences in cholesterogenesis under various conditions was validated by using rats fed on cholesterol or cholestyramine. Cholesterol feeding resulted in decreased cholesterogenesis, whereas cholestyramine caused an increase. 3. With acetate as precursor, the biosynthesis of both digitonin-precipitable sterol and fatty acids was increased in vitro in response to a meal. 4. In rats fed ad libitum, hepatic cholesterogenesis was increased at midnight relative to mid-morning as measured by using acetate precursor in vitro. However, no such difference was found by using 3H2O in vivo. 5. The lipogenic response was measured in meal-fed rats by using 3H2O or octanoate in vivo. In contrast with findings with acetate in vitro, no postprandial stimulation of cholesterogenesis was seen with either 3H2O or octanoate as precursor, whereas fatty acid biosynthesis from either substrate was increased. 6. These findings are discussed with respect to current theories about the circadian rhythm of cholesterogenesis. Such theories are based on experiments using isolated enzyme measurements or non-physiological precursors such as acetate. 7. It is considered that results obtained with 3H2O give an accurate representation of cholesterogenesis under various conditions, and it is therefore suggested that hepatic cholesterogenesis in rats is not subjected to the same degree of diurnal rhythm as has previously been believed.     

Activated carbon adsorption of cyanide complexes and thiocyanate ion from petrochemical wastewaters

Experimental isotherms indicate that thiocyanate and nickel cyanide complex (tetracyanonicklate (II)) adsorb to an equal extent from synthetic and actual waste solutions at loadings below 10 mg/g carbon. Loading of nickel hexammine complex is an order of magnitude less. Adsorption of the divalent nickel cation is strongly pH dependent and is believed to be a chemisorption by precipitation or reaction on the carbon surface. In pure solution, ferrocyanide (hexacyanoferrate (II)) adsorption was comparable to that of thiocyanate or nickelocyanide, but adsorption from the waste liquor tested was negligible. This difference may be due to solvation of ferrocyanide with methanol in the wastewater to form a species with entirely different adsorption characteristics. Chemical oxygen demand (COD) values were obtained for several of the pure materials (SCN^?, 1.1; Fe(CN)₆^?4, 0.5; Ni(CN)₄^?2, 0.4 mg $\text{COD}\text{mg}$ ion) and the wastewater to monitor adsorption of organic background materials.     

Dihydropyrimidine dehydrogenase activity in cancer patients

Dihydropyrimidine dehydrogenase (DPD) is the major catabolic enzyme of pyrimidines and fluoropyrimidines. The clinical course of 2 patients with suspected DPD deficiency is described. Both patients had significantly delayed clearance of fluorouracil (5-FU), elevated plasma uracil concentrations, and subsequent lethal toxicity. The prevalence of DPD deficiency in the general population is unknown, but given the large number of cancer patients treated with 5-FU, it may be of great clinical significance. Lymphocytes have been previously shown to be a useful marker of systemic DPD activity. Because DPD activity has not been previously reported in a large population of cancer patients using 5-FU as the substrate, we determined DPD activity in lymphocytes from 66 patients with cancer. DPD activity was determined by a sensitive high performance liquid chromatography method. The mean DPD activity (S.D.) in 66 patients with head and neck cancer was 0.189 (0.071) nomol/min/mg protein with wide interpatient variability (range 0.058-0.357). DPD activity was not correlated to age (r = -0.164, P = 0.188). The mean DPD activity in men [0.192 (0.074)] was not significantly different from that in women [0.172 (0.057); t-test P = 0.418]. Likewise, there was no statistical difference in DPD activity in patients who had not received prior chemotherapy [0.195 (0.066)] to patients receiving one or more cycles of chemotherapy [0.186 (0.074); t-test P = 0.638].     

Infarct sizing with technetium-99m stannous pyrophosphate scintigraphy in dogs and man; relationship between scintigraphic and praecordial mapping estimates of infarct size in patients

The dynamics of changes in serum lipids (free fatty acids, free glycerol, triglycerides, total cholesterol, and phospholipids) were studied in male Wistar rats irradiated in an open experimental field with a daily dose of 15.48 mC.kg.--1 (60 R) up to a total exposure of 774.0 mC. kg.--1 (3,000 R). The resulting changes occurred in several periods. Initial period of 0--7 days included a drop in triglyceride level and a rise in free glycerol, total cholesterol, and phospholipids in both control and irradiated rats. The period of 14--25 days marked the appearance of serum hyperlipaemia. Between 25--50 days, the levels of the different fractions oscillated and existing changes became more pronounced. The general level of serum lipids during continuous gamma-irradiation exceeded that found in controls. Changes in control animals from experimental field reflected the influence of a changed environment. The modifying factor affecting both irradiated and control rats was night fasting prior to sacrificing the animals and, probably, also the presence of an infradian rhythm in some serum lipid fractions.     

Selective analysis for adenosine using reversed-phase high-pressure liquid chromatography

A high-pressure liquid chromatographic procedure for the selective determination of adenosine in the presence of other nucleic acid components is reported. Reversed-phase microparticle columns and an isocratic elution mode of dilute potassium dihydrophosphate and anhydrous methanol were used. The analysis is specific for adenosine and is achieved in less than 10 min. An example of the use of this analysis in a biomedical study is reported.     

Outbreaks of trypanosomosis due to Trypanosoma vivax in cattle in Bolivia

Some new commercial methods for the extraction of viral RNA have been introduced recently. In addition to the study published previously (Verhofstede, C., Reniers, S., Van Wanzeele. F., Plum J., 1996. AIDS 8, 1421-1427), seven different methods (four newly developed and three reference methods) for extraction of HIV-1 RNA from plasma have been evaluated. The RNA preparation method that gave the best results (acceptable reproducibility, highest sensitivity, reasonable price, fast and easy to perform), was the QIAamp Viral RNA kit from QIAgen. The High Pure Viral RNA Kit (Boehringer Mannheim) as well as the non-commercialised extraction kits were also very sensitive. The non-commercial tests seem less suitable for routine use and for the processing of large number of samples. Two methods, RNA Insta-Pure LS (Eurogentec) and PANext RNA extraction kit 1 (NTL, PANsystems GmbH) are not adapted for HIV plasma extraction. The single step methods using glass fibre or silica column are rapid (from 60 to 75 min depending on the number of wash steps) and although the price is high they are cheaper than the Boom extraction methods: High Pure Viral RNA Kit (Boehringer Mannheim) ($3.3/sample), QIAamp Viral RNA Kit (Qiagen) ($3.6/sample), Boom extraction ($5/sample). The Qiagen kit is the only kit that combines sensitivity with reproducibility, it is commercialised, rapid and affordable in price and can be automated. For most of the methods evaluated the inter-test variability was acceptable (mean variation coefficient between duplicate extractions varied between 26.4 and 48.6%).     

Platynosomum fastosum in ex-captive orangutans from Indonesia

The liver fluke Platynosomum fastosum was identified upon necropsy of three ex-captive orangutans (Pongo pygmaeus) which had been part of a rehabilitation program for reintroduction to the wild. This trematode has not been reported in orangutans previously and is commonly found in cats in Southeast Asia. Cross infection from cats via intermediate hosts, to orangutans kept in captivity as pets, could explain their presence in the latter. Although P. fastosum caused intrahepatic and bile duct damage, death of the hosts could not be attributed solely to the presence of the liver fluke infection.     

A family of Arf effectors defined as suppressors of the loss of Arf function in the yeast Saccharomyces cerevisiae

Arf proteins are ubiquitous, eukaryotic regulators of virtually every step of vesicular membrane traffic. ADP-ribosylation factors are essential in yeast and the lethality resulting from either overexpression or underexpression (deletion) of Arf genes has previously been ascribed to dysregulation of the secretory process. We have identified a family of four genes (Suppressors of Arf ts, SAT) as high copy suppressors of a loss of function allele of ARF1 (arf1-3). Those proteins with SAT activity were found to contain a minimal consensus motif, including a C2C2H2 cluster with a novel and specific spacing. Genetic interactions between members of this family and with ARF1 are consistent with each sharing a common cellular pathway. Included in this family is Gcs1, a protein previously described (Poon, P. P., Wang, X., Rotman, M., Huber, I., Cukierman, E., Cassel, D., Singer, R. A., and Johnston, G. C. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 10074-10077) to possess Arf GTPase-activating protein (GAP) activity, demonstrating a direct interaction between Arf and at least one of these suppressors. The suppression of the loss of Arf function by overexpression of Gcs1 and demonstration of direct, preferential binding of Gcs1 to the activated form of Arf (Arf.GTP) lead us to conclude that the biological role of Gcs1 is as an effector of the essential function of Arf in mitotic growth, rather than a down-regulator as implied by the biochemical (Arf GAP) activity. Suppression of the growth defect of arf1(-3) cells was observed under conditions that did not alter the secretory defect associated with arf1(-) mutation, indicating that the essential role of Arf in eukaryotes can be distinguished from role(s) in the secretory pathway and appear to employ distinct pathways and effectors.