Sodium nitroprusside: pharmacology, toxicology and therapeutics

Sodium nitroprusside is a potent, effective, and readily reversible direct vasodilating agent. It is broken down by hemoglobin into cyanide, which is in part detoxified by liver and kidney to thiocyanate. Some cyanide, especially in nitroprusside- "resistant" individuals who need large amounts of the drug, appears to remain free to cause cyanide poisoning. Patients requiring inordinate amounts probably should not continue to receive the drug, although maximum dosage limits for long-term therapy are not established. Blood thiocyanate levels do not indicate the extent to which free cyanide is limiting oxygen utilization in essential tissue, nor do blood cyanide levels. Metabolic acidosis, elevated lactate levels, elevated lactate/pyruvate ratios, and elevated mixed venous blood oxygen content are at present the best indications of the presence of cyanide poisoning during nitroprusside administration. Nitroprusside appears useful for induction of hypotension during surgery, and for treatment of hypertensive emergencies from all causes, although continuance for more than a few days is probably unwise. The reductions of cardiac afterload and ventricular filling pressure by nitroprusside appear useful in treatment of severe myocardial failure or infarction, but studies of myocardial cyanide toxicity are needed before complete acceptance of this therapy is warranted. Initial dose rates between 0.5 and 1.5 mug/kg/min are recommended only as starting points for very careful titration. Total projected intra-operative dosage should be calculated as quickly as possible and should not exceed 3-3.5 mg/kg. It is hoped that future studies will reveal the maximum dose of nitroprusside that can safely be metabolized in a 24-hour period, and may indicate that cofactors of rhodanase such as thiosulfate, or cobalamins such as hydroxocobalamin, can be administered with nitroprusside to prevent cyanide poisoning.     

Conservative management of chronic renal failure

Failing kidneys can play havoc with other parts of the body. Specific treatment of these associated problems may help ward off uremia and preserve whatever renal function remains. Sodium levels may drop if too much water is mistakenly given to counteract kidney failure. Hyperkalemia can lead to cardiac arrest if potassium levels aren't reduced without delay. Acidosis also may reach life-threatening proportions, especially if diarrhea occurs. Almost all patients with chronic renal failure have a bleeding tendency and anemia, with the hematocrit dipping as low as 20 percent. Over half have decreased tolerance to carbohydrares, although severe hyperglycemia is rare. Disorders of calcium metabolism also are common, ranging from asymptomatic hypocalcemia to osteomalacia. The kidneys' impaired filtration ability should be kept in mind when drugs are prescribed. Dosages may need to be cut to avoid an adverse reaction.     

Conformations of satellite DNAs

X-ray fiber diffraction studies of satellite DNAs from Gecarcinus lateralis, Drosophila virilis and Mus musculus, all of which have highly repetitious base sequences but with different degrees of sequence complexity, reveal only classical polynucleotide duplex structures in contrast to some highly repetitious synthetic DNAs.     

Synthesis in vitro of intrinsic membrane proteins by free, membrane-bound, and Golgi apparatus-associated polyribosomes from rat liver

A fraction of intrinsic membrane proteins was prepared from the major membranous cell components of rat liver by extraction of the membranes with KCl and deoxycholate. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the compositions of the intrinsic protein fractions from rough and endoplasmic reticulum, smooth endoplasmic reticulum. Golgi apparatus, plasma membrane, and nuclear envelope were similar to each other but distinct from that of mitochondria. Among endomembranes, differences were in the ratios of protein constituents plus a few protein bands of Golgi apparatus and plasma membranes not found in endoplasmic reticulum or nuclear envelope. The abilities of total rough endoplasmic reticulum, polysomes released from rough endoplasmic reticulum, and free polysomes to incorporate amino acids into the intrinsic protein fraction were tested in vitro. Polysomes bound to endoplasmic reticulum has the greatest capacity to synthesize proteins of this fraction as shown by co-purification of radioactive products and by immunoprecipitation. Although the majority of the radioactive products synthesized by bound polysomes were distinct from those synthesized by free polysomes, certain radioactive products synthesized by free polysomes also co-purified with intrinsic membrane proteins. The results show no absolute segregation between free and bound polysomes in the synthesis of intrinsic membrane proteins. However, the majority of these proteins appear to be synthesized by polysomes bound to the endoplasmic reticulum. Several intrinsic proteins found in plasma membranes do not appear in rough endoplasmic reticulum. To determine where these proteins were synthesized, the ability of other endomembrane components to support in vitro incorporation of [14C]leucine into protein was examined. In contrast to plasma membranes, isolated Golgi apparatus fractions did incorporate [14C]leucine to an extent greater than could be explained by contamination with rough endoplasmic reticulum. Golgi apparatus in situ and isolated from rat liver have polyribosomes associated with a zone of cytoplasm at the Golgi apparatus periphery occupied by tubules and vesicles. The polysomes are not directly attached to membranes as with rough endoplasmic reticulum and may represent a special class of "Golgi apparatus-associated" polysomes. The polysomes, when associated with Golgi apparatus membranes, incorporated amino acids in vitro. The products synthesized in vitro were analyzed by treatment with KCl and deoxycholate and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Certain proteins synthesized by the Golgi apparatus-associated polysomes remained insoluble after the treatment with KCl and deoxycholate. The proteins synthesized by the Golgi apparatus fraction had mobilities similar to proteins in plasma membranes which were absent from endoplasmic reticulum, and which were relatively minor components of Golgi apparatus...     

Effects of germination on the activities of amylases and phenolic enzymes in sorghum varieties grouped according to food end‐use properties

Fifty sorghum varieties were screened to determine the effects of germination on levels of starch, α‐amylase, β‐amylase, phenylalanine ammonia lyase (PAL), peroxidase (POX) and polyphenol oxidase (PPO). Germination decreased starch content, with amylose being more degraded than amylopectin. In germinated grain, α‐amylase activity increased several‐fold in all varieties, whereas β‐amylase activity did not increase uniformly and even decreased in some varieties. Activity of the key enzyme in phenolic biosynthesis, PAL, was detected in only half of the varieties before germination but in all of them after germination. PPO was not activated in germinated sorghum grains, whereas POX activity increased up to tenfold in some varieties. Zymography revealed that germination induced de novo synthesis of several POX isoenzymes, among which an anionic POX isoenzyme (pI 3.1) was ubiquitously present. Amylase and phenolic enzyme activities could be correlated with grain and plant agronomic characteristics. The use of sorghum varieties for local dishes such as ‘tô’, ‘dolo’, couscous and thin porridge could be correlated with amylase and phenolic enzyme activities and the contents of their substrates. The biochemical constituents determined are useful markers for selection of varieties for food utilisation with special emphasis on infant porridges. Copyright © 2006 Society of Chemical Industry     

Hexanal as a marker of oxidation flavour in sliced and uncured deli turkey with and without phosphates using rosemary extracts

Ability of commercial rosemary extracts (REs) alone and in combination with sodium tripolyphosphate (P) to inhibit lipid oxidation in uncured deli turkey (UDT) was examined via headspace hexanal and oxidation flavour. Sliced UDT was packaged (75% N₂/25% CO₂) and stored 13 weeks at 4 °C. Addition of P decreased hexanal 2.4-fold (P < 0.05) and increased mean pH of UDT from 5.94 to 6.30 (P < 0.05). Addition of water/lipid-soluble RE did not inhibit hexanal formation in UDT. Addition of water-soluble RE decreased hexanal 2.2-fold (P < 0.05). The combination of P and water-soluble RE decreased hexanal 33-fold (P < 0.05). The combination of P and water/lipid-soluble RE decreased hexanal ninefold (P < 0.05). Oxidation flavour was highest in UDT without added antioxidant> RE> P> RE+P (P < 0.05). Hexanal values were positively correlated with oxidation flavour scores throughout storage (P < 0.05). The combination of P with either RE was particularly effective at inhibiting lipid oxidation in modified atmosphere packaged UDT.     

Attachment of Salmonella Poona to cantaloupe rind and stem scar tissues as affected by temperature of fruit and inoculum

A negative temperature differential between fruits or vegetables and the water in which they are immersed theoretically enhances infiltration of water and any microorganisms it might contain into tissues. The effect of temperature differentials between cantaloupes and wash water, each at 4 and 30 degrees C, on changes in cantaloupe weight and populations of Salmonella enterica Poona recovered from rinds and stem scar tissues of Eastern and Western (shipper) types of cantaloupes was assessed. The percent weight increase in Western cantaloupes was significantly greater (P < or = 0.05) than that in Eastern cantaloupes for all cantaloupe and inoculum temperature combinations. Salmonella Poona attachment to or infiltration of Eastern but not Western cantaloupe rind is enhanced when the fruit is at 4 degrees C, compared with 30 degrees C, regardless of the temperature of the immersion suspension. The number of Salmonella Poona cells recovered from rind tissue of Western cantaloupes at 30 degrees C immersed in inoculum at 30 degrees C was significantly less (P < or = 0.05) than that recovered from rind tissues of cantaloupes at 4 or 30 degrees C that were immersed in inoculum at 4 degrees C. Salmonella Poona in immersion water can adhere to or infiltrate surface tissues of cantaloupes. The populations of Salmonella Poona recovered from stem scar tissues of Eastern and Western types of cantaloupes were not significantly (P > 0.05) affected by cantaloupe and inoculum temperature combinations. Populations of cells adhering to or infiltrating various cantaloupe tissues is not dictated entirely by temperature differentials between fruits and immersion suspensions: rather, it also apparently is influenced by structures unique to surface tissues.     

Changes in heme proteins and lipids associated with off-odour of seabass (Lates calcarifer) and red tilapia (Oreochromis mossambicus × O. niloticus) during iced storage

Changes in heme proteins and lipids associated with off-odour development in seabass (Lates calcarifer) and red tilapia (Oreochromis mossambicus × O. niloticus) muscles during 15 days of iced storage were studied. Fresh seabass contained the higher contents of myoglobin and heme iron, compared with red tilapia (P < 0.05). An increase in metmyoglobin proportion was observed during storage. After 3 days of storage, a decreased heme iron content and a concomitant increase in non-heme iron content were noticeable in both fish (p < 0.05). Oxidation of myoglobin and released non-heme iron were associated with lipid oxidation. The increases in oxidation products and free fatty acids were observed as the storage time progressed. Fishy and rancid odours were detected at day 6 of storage for both fish and a higher intensity was found in seabass muscle. Thus, the off-odour in fish muscle was mostly governed by lipid oxidation and species specific.     

Research of Genetic Polymorphism Species Linumu sitatissimum L. on a Basis a RAPD-Method

The goal of this investigation was the interpretation of genetic polymorphism in flax using the random amplified polymorphic DNA (RAPD-PCR) technique in relation to genealogical information and eco geographic origin of the accessions. Protein markers have been successfully applied for identification of ecotypes of cultivated plants and for cultivar identification and registration. However, for intraspecific differentiation in flax effective protein markers have not been found. The DNA markers developed during the recent decades proved to be more efficient in detecting polymorphism in flax. The plant material were 287 accessions from the flax collection at the All-Russian Flax Research Institute (VNIIL) belonging to different botanical and eco-geographical groups based on the classification of the species Linumu sitatissimum L. On the basis of a molecular estimation the gene pool offlax it can be assumed that the fiber flax from northern continental Russia is not exclusively of Indo-afghan origin as suggested by Sinskaja (1959), but also has genetic roots in flax from Kolchidian. Essential genetic similarity between cultivar of fiber flax from Russia and other the European countries is established. Results of a generality of an origin of fiber flax cultivar from Russia are confirmed also with the analysis of their genealogy. Essential genetic polymorphism of linseed flax is shown. The distinctness of linseed and fiber flax in their genetic constitution as revealed by the RAPD analysis is of strategic importance in preservation of the genetic diversity and for efficient use of the flax gene pool in breeding.     

Production of Gas Phase NO(2) and Halogens from the Photochemical Oxidation of Aqueous Mixtures of Sea Salt and Nitrate Ions at Room Temperature

Nitrate and halide ions coexist in a number of environmental systems, including sea salt particles, the Arctic snowpack, and alkaline dry lakes. However, little is known about potential synergisms between halide and nitrate ions. The effect of sea salt on NO(3)(-) photochemistry at 311 nm was investigated at 298 K using thin films of deliquesced NaNO(3)-synthetic sea salt mixtures. Gas phase NO(2), NO, and halogen products were measured as a function of photolysis time using NO(y) chemiluminescence and atmospheric pressure ionization mass spectrometry (API-MS). The production of NO(2) increases with the halide-to-nitrate ratio, and is similar to that for mixtures of NaCl with NaNO(3). Gas phase halogen production also increased with the halide-to-nitrate ratio, consistent with NO(3)(-) photolysis yielding OH which oxidizes halide ions in the film. Yields of gas phase halogens and NO were strongly dependent on the acidity of the solution, while that of NO(2) was not. An additional halogen formation mechanism in the dark involving molecular HNO(3) is proposed that may be important in other systems such as reactions on surfaces. These studies show that the yield of Br(2) relative to NO(2) during photolysis of halide-nitrate mixtures could be as high as 35% under some atmospheric conditions.