The pharmacological and pathological studies on several hepatic protective crude drugs from Taiwan (I)

This study is to investigate the hepatic protective effect of several Taiwan crude drug extractions on the carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. The pharmacological and pathological effects of Bupleurum chinense, Phellodendron wilsonii, Clematis chinensis and Hedyotis corymbosa were analyzed by liver enzyme function test and pathological studies. However, the results of amine transferase SGOT and SGPT have shown a significant hepatic protective effect after treatment with Bupleurum chinense (P less than 0.005), Phellodendron wilsonii (P less than 0.001), Clematis chinensis (P less than 0.005) and Hedyotis corymbosa (P less than 0.005, SGPT only). The fatty degeneration around the central vein area and necrosis of the central lobule can be significantly improved by P. wilsonii and moderately changed by B. chinense or C. chinensis. Although fatty metamorphosis has been affected by H. corymbosa, various inflammatory cell infiltrations in the cytoplasm were noted.

Role of the N-terminal region in phospholipases A2 from Naja naja atra (Taiwan cobra) and Naja nigricollis (spitting cobra) venoms

The N-terminal alpha-amino groups of two phospholipases A2 (PLA2) from Naja naja atra and Naja nigricollis venoms were selectively modified with trinitrobenzene sulfonic acid, and the modified derivatives were separated by high performance liquid chromatography (HPLC). Trinitrophenylated (TNP) derivatives contained only one TNP group in the alpha-amino group of Asn-1 and showed a marked decrease in enzymatic activity. PLA2 enzymes were cleaved with CNBr, and the N-terminal octapeptide was separated from the large C-terminal fragment by HPLC. Removal of the N-terminal octapeptide from PLA2 enzymes caused a precipitous decrease in enzymatic activity. Enzyme immunoassay and double immunodiffusion revealed that the N-terminal octapeptide is one of the antigenic determinants of PLA2 enzymes. The presence of dihexanoyllecithin influenced the interaction between PLA2 enzymes and 8-anilinonaphthalene sulfonate (ANS), indicating that ANS-binding site of PLA2 enzymes is at or near the substrate binding site. Modification of the N-terminal region perturbed the substrate binding and the binding ability for ANS. The modified derivatives retained their affinity for Ca2+, indicating that the N-terminal region is not involved in Ca2+-binding. A fluorescence study revealed that the alpha-amino group is near Trp residue(s) and that the N-terminal region is important for stabilizing the architectural environment of the Trp residue(s). The results, together with the proposal that Trp residues in PLA2 enzymes are involved in substrate binding, suggest that the N-terminal region of PLA2 enzymes is involved in substrate binding and in maintaining a functional active site.

First and second moments of an optical wave propagating in an absorptive random medium

By using the path-integral technique, the first and second moments of the propagator in an absorptive random medium are evaluated. The effects of random fluctuations of absorption are taken into account. In this evaluation, the imaginary part of the dielectric permittivity is supposed to fluctuate synchronously with the real part according to the Kramers-Kronig relations. Some physical insight is discussed.

Different susceptibilities of platelet phospholipids to various phospholipases and modifications induced by thrombin. Possible evidence of rearrangement of lipid domains

On the membrane surface of the human platelet, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were hydrolyzed to different extents by the snake venom phospholipases A2 of varying pI values. The susceptibility of platelet phospholipids to basic phospholipase A2 of Naja nigricollis (pI 10.6) has been reported (Wang et al. (1986) Biochim. Biophys. Acta 856, 244-258). The susceptibilities of platelet phospholipids to acidic phospholipase A2 of Naja naja atra (pI 5.2) and to neutral phospholipase A2 of Hemachatus haemachatus (pI 7.3) were investigated in this study. In gel-filtered platelets, acidic phospholipase A2 hydrolyzed 35% PC and 10% PE, while neutral phospholipase A2 hydrolyzed 18% PC and 3% PE. In thrombin-induced shape-changed platelets, acidic phospholipase A2 hydrolyzed 20% PC and 10% PE, while neutral phospholipase A2 hydrolyzed 15% PC and 6% PE. In thrombin-activated platelets, acidic phospholipase A2 hydrolyzed 25% PC and 7% PE, while neutral phospholipase A2 hydrolyzed 25% PC and 10% PE. Sequential lipid hydrolysis experiments showed that basic phospholipase A2 of Naja nigricollis could hydrolyze the remaining PC and PE in the membrane previously treated with the neutral enzyme. The results may mean that: the PC and the PE domains exist on the platelet membrane surface; and the lipid domains on the membrane surface of resting platelets are rearranged by thrombin.

Normal T cell subsets in homosexual men living in a community without endemic AIDS

The cause of the abnormal T lymphocyte subsets reported in healthy homosexual men is not known. Frequent sexually transmitted infections including human T cell lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) are possible causes. To determine if the T lymphocyte subsets were abnormal in this population in an area without endemic acquired immune deficiency syndrome (AIDS), T lymphocyte subsets of 52 homosexual men in Rochester, New York, were enumerated, and evidence of infections known to cause these abnormalities was sought. Unlike the findings in previous reports, relative numbers of T helper and T suppressor cells and helper/suppressor T cell ratios were normal. Prevalence of cytomegalovirus infection (86 percent) was similar to that found in analogous populations, but only 9 percent had seropositive results for HTLV-III/LAV. Men with serologic evidence of nonprimary cytomegalovirus disease had lower helper/suppressor T cell ratios (1.5 +/- 0.2 versus 2.2 +/- 0.2; p less than 0.01). Hence, despite frequent infections with cytomegalovirus and other sexually transmitted pathogens, T cell subsets are normal in homosexual men in an area without endemic AIDS. Therefore, HTLV-III/LAV is primarily responsible for the T cell abnormalities observed elsewhere.

Pulmonary surfactant activity after severe steam inhalation injury in rabbits

Lung water content, Pao2, surface tension (in terms of hysteresis) and lecithin content of both bronchial irrigation fluid and lung homogenates were determined after severe steam inhalation injury in rabbits. At the time of a decrease in Pao2 and an increase in lung water content there was a moderate fall in pulmonary surfactant activity; as shown by a progressive decrease in the area of the hysteresis loop and a decrease of the lecithin content in both bronchial irrigation fluid and lung homogenate. It is proposed that a fall in pulmonary surfactant activity plays an important role in the pathogenesis of pulmonary oedema after inhalation injury. Successive determinations of lecithin content and/or surface tension of bronchial irrigation fluid are recommended as early diagnostic and prognostic aids in severe inhalation injury.

The relationship between high-affinity noncatalytic binding of snake venom phospholipases A2 to brain synaptic plasma membranes and their central lethal potencies

The basic phospholipase A2 from Naja nigricollis (African spitting cobra) snake venom is enzymatically less active but more toxic than the acidic phospholipase A2 from Naja naja atra (Taiwan cobra) snake venom, following injection into the right lateral ventricle of the brain of rats. When radiolabeled with 125I, these phospholipases A2 retained enzymatic activities and lethal potencies. Both enzymes bound with high affinity and specificity to brain synaptic plasma membrane preparations in vitro even in the absence of calcium, suggesting a non-catalytic binding. The acidic enzyme, in a calcium-free medium, had two binding components with Kd values of 1 X 10(-10) and 2.75 X 10(-8) M and Bmax values of 6 X 10(-13) and 3.4 X 10(-11) mol/mg, respectively. Multiple specific and nonspecific binding components were observed for each phospholipase A2; saturability for all of the binding sites was conclusively demonstrated only for the N. naja atra phospholipase A2 in a calcium-free medium (Bmax = 3.4 X 10(-11) mol/mg). The levels of specific and total binding were 150 pmol/mg and 450 pmol/mg, respectively, for the comparatively toxic enzyme and 15 pmol/mg and 35 pmol/mg, respectively, for the comparatively nontoxic enzyme at a concentration of 2.5 X 10(-8) M. These levels of binding (both total and specific) were directly correlated with the intraventricular lethal potencies of the phospholipases A2 (0.5 and 5.0 micrograms/rat for the N. nigricollis and N. naja atra phospholipases A2, respectively), suggesting a possible relationship between binding and lethal potency. Carbamylation of lysines reduced the levels of binding and the lethal potencies of both enzymes to a greater extent than their enzymatic activities. Pretreatment with high temperature, proteinases, phospholipases A2 or C suggested that radiolabeled phospholipase A2 binds to phospholipids rather than proteins. However, only the N. naja atra phospholipase A2 manifested a strict dependence on a divalent cation (Ca2+ or Sr2+) for most of its binding. The N. nigricollis enzyme demonstrated a much lower rate of dissociation from synaptic plasma membranes than did N. naja atra phospholipase A2, suggesting that hydrophobic interactions are more important in the binding of the more toxic enzyme as compared to the less toxic enzyme. It is proposed that differences in the extent of high-affinity noncatalytic binding to membrane phospholipids may be at least partly responsible for the marked difference in central toxicities of these two phospholipases A2.

Estimation of the phospholipid distribution in the human platelet plasma membrane based on the effect of phospholipase A2 from Naja nigricollis

Human platelets in three physiological states were prepared. These states were the gel-filtered, the thrombin-induced shape-changed, and the thrombin-activated platelets. The phospholipid distributions in these three types of membrane were probed by using the basic phospholipase A2 of Naja nigricollis. This enzyme could penetrate through these membranes to hydrolyze all of their accessible phospholipids and to cause cell lysis. The hydrolytic time-courses displayed three phases. The state of platelet in each lipid hydrolytic phase was examined by: (1) measuring the leakage of lactate dehydrogenase; (2) analyzing the morphology by both scanning and transmission electron microscopy (scanning EM and transmission EM); and (3) estimating the hydrolysis of the [32P]phosphate-labeled platelets. The existence of these three hydrolytic phases may signify that the phospholipase A2 sequentially hydrolyzed its substrates in the membrane outer leaflet, in the inner one, and in the cytosol. The content and the distribution of each phospholipid class in the plasma membranes of the resting and of the shape-changed platelets were similar. These membrane surfaces consisted mainly of phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Phosphatidylserine (PS) was not exposed on the surface of the shape-changed platelet. The content of each lipid class in the activated platelet membrane was 10% more than that in the resting platelet. PS was found on the activated platelet cell surface. This implies that PS is exposed only during platelet secretion.

Effects of modification of tyrosines 3 and 62 (63) on enzymatic and toxicological properties of phospholipases A2 from Naja nigricollis and Naja naja atra snake venoms

Previously we selectively modified His (48), Arg, Lys, Asp, Glu and Trp residues in the basic phospholipase A2 from Naja nigricollis and the acidic phospholipase A2 from N. n. atra snake venoms. Evidence was obtained for the existence of separate but perhaps overlapping sites responsible, respectively, for their enzymatic and pharmacological properties. We have now modified one or two (Tyr 3, Tyr 62 [63], Tyr 3 + 62 [63]) out of the nine tyrosine residues in these enzymes using p-nitrobenzenesulfonyl fluoride. The derivatives were separated by HPLC, and modified residues determined by amino acid analysis. Enzymatic activity was tested on lecithin--Triton mixed micelles, egg yolk and heart and diaphragm homogenates. The N. nigricollis modified derivatives retained a greater percentage of their enzymatic activities than did the N. n. atra derivatives and also a greater percentage of their activity on natural substrates than on lecithin--Triton mixed micelles. The greatest loss in activity resulted when both tyrosines were modified and the least when tyrosine 3 was modified. Modification of tyrosine 62 of N. nigricollis caused a much greater loss of intraventricular lethal potency than of enzymatic activity, whereas modification of tyrosine 3 of N. n. atra increased lethal potency over six-fold while enzymatic activity decreased about 60%. Examples of dissociation between enzymatic and pharmacological potencies were also noted when hemolytic, anticoagulant and cardiotoxicity on isolated ventricular muscle were measured. The extents of phospholipid hydrolysis were relatively low in brain homogenates, synaptic plasma membranes and heart ventricular muscle. However, they were similar for the native enzymes and all of the tyrosine modified derivatives. These tyrosines do not appear to be part of the enzymatic active site, even though they are thought to be associated with substrate and calcium binding. These results strengthen our earlier conclusion that some pharmacological effects of phospholipase A2 are not due to enzymatic hydrolysis, and that there are separate but perhaps partly overlapping sites for enzymatic and pharmacological activities.

Circular dichroism study of the unfolding-refolding of a cardiotoxin from Taiwan cobra (Naja naja atra) venom

Circular dichroism spectroscopy has been used to study the unfolding-refolding process of a cardiotoxin from Taiwan cobra (Naja naja atra) venom upon addition of fluoroalcohols or sodium dodecyl sulfate (SDS) to its aqueous solution. In these experiments, the disulfide bridges remained intact. The unfolding process has been found to be reversible both for fluoroalcohols and for SDS unfolding. The reversibility of the unfolding-refolding process of cardiotoxin in aqueous mixtures of fluoroalcohols was dependent on the volume per volume ratio of alcohol to water. SDS did not unfold the secondary structures of cardiotoxin whereas its tertiary structure was affected. If the SDS concentration in aqueous solution exceeded the critical micelle concentration value of SDS, a quasi-refolded state of cardiotoxin was observed. The mechanism of unfolding-refolding is discussed in terms of molecular interactions which might govern the protein conformation in solution.

Amnion overlay meshed skin autograft

Meshed skin autografts are conventionally dressed with fine petrolatum gauzes. Pain and haemorrhage are a frequent sequel to changing dressings in the early days after grafting. We have explored the use of amnion to overlay the meshed autograft (3:1) in addition to the fine petrolatum gauze. Eleven patients with 24 burn wounds were treated. The amnion provided good protection to the underlying meshed autograft and the neoepithelium. It did not block the re-epithelialization and may have promoted the healing process. Most of the grafts had healed completely by 7 days after application. Pain and haemorrhage were markedly reduced. The non-antigenic nature, adherent quality and inexpensive cost makes amnion a promising biological dressing for meshed autografts.

Effect of alkylation of tryptophan residues on the enzymatic and pharmacological properties of snake venom phospholipase A2

Snake venom phospholipases A2 show a remarkable degree of amino acid sequence homology yet differ markedly in enzymatic and pharmacological activities. The basic phospholipase A2 from Naja nigricollis venom has much greater lethal potency, cardiotoxicity, hemolytic and anticoagulant activity than the acidic or neutral enzymes from Naja naja atra or Hemachatus haemachatus venoms, respectively, even though it has lower enzymatic activity than the latter two enzymes. Previous studies in which we selectively modified lysine and free carboxyl groups suggested that the pharmacological and enzymatic active sites are not identical. Tryptophan residues have been suggested as being involved in substrate binding although some phospholipases have no tryptophan. We investigated the effect of alkylating the tryptophans in N. nigricollis, N. n. atra, and H. haemachatus phospholipases A2 with 2-hydroxy-5-nitrobenzyl bromide. Chemical modification caused decreases in enzymatic activity, although the extent of inactivation varied with the enzyme and with the substrate (lecithin micelles, egg yolk, heart homogenates). The specificity of the enzymes for individual phospholipid substrates was not affected. Alkylation of the tryptophans also caused decreases in lethal, hemolytic, anticoagulant, and cardiotoxic potencies, which were similar to the extents of decrease in enzymatic activity. Our results suggest that tryptophans are not specifically associated with either the enzymatic or the pharmacological active site nor are essential for either activity.

Cardiotoxic effects of Naja nigricollis venom phospholipase A2 are not due to phospholipid hydrolytic products

N. nigricollis phospholipase A2 (200 micrograms) has marked cardiotoxic actions on the perfused rat heart including the induction of arrhythmias, increases in ventricular thresholds, conduction and resting tension, and decreases in contractile tension. In contrast, perfusion with lysophosphatidyl choline and oleic acid, in concentrations comparable to those estimated to be formed during N. nigricollis treatment, has little effect on cardiac function. The less toxic N. n. atra phospholipase A2 also has little effect on cardiac function even though it causes approximately the same low percentage of phospholipid hydrolysis as produced by N. nigricollis phospholipase A2. Perfusion with albumin did not alter the phospholipase A2 induced changes in cardiac function. Lysophosphatidyl choline in concentrations higher than expected to be formed during N. nigricollis phospholipase A2 treatment, increased conduction time to a greater extent than ventricular threshold whereas the reverse was true for phospholipase A2. We conclude that the cardiotoxic effects of N. nigricollis phospholipase A2 are not due to the accumulation of phospholipid hydrolytic products, and on the basis of prior studies with chemically modified phospholipase A2 enzymes we suggest that N. nigricollis phospholipase A2 has a direct, non-enzymatic, cardiotoxic action.

Structure of pseudobactin 7SR1, a siderophore from a plant-deleterious Pseudomonas

When grown in iron-limiting culture medium, sugar beet deleterious Pseudomonas 7SR1 produced extra-cellularly the yellow-green, fluorescent siderophore pseudobactin 7SR1. Pseudobactin 7SR1 had a molecular formula of C46H63N13O23 and a molecular mass of 1166 g/mol. Pseudobactin 7SR1 contained a cyclic octapeptide with the amino acid sequence L-Ala-Gly-Ser-Ser-threo-beta-OH-Asp-Thr-Ser-N delta-OH-Orn. Since pseudobactin 7SR1 was not affected by nonspecific enzymes, it might contain D-amino acids. A yellow-green, fluorescent quinoline derivative is postulated to be attached via an ester bond to the serine residue following the glycine. A malamide group was attached to carbon 3 of the quinoline derivative. The three bidentate iron(III)-chelating groups consisted of an alpha-hydroxy acid group derived from beta-hydroxyaspartic acid, an omicron-dihydroxy aromatic group derived from the yellow-green, fluorescent chromophore, and a hydroxamate group derived from N delta-acetyl-N delta-hydroxyornithine. The chemical structure of pseudobactin 7SR1 is remarkably similar to that of pseudobactin, the siderophore of plant growth promoting Pseudomonas B10.

Colicin V-treated Escherichia coli does not generate membrane potential

Colicin V-treated Escherichia coli was inhibited in its capacity to carry out active transport of proline and was unable to generate a membrane potential. Colicin V also prevented membrane potential formation by isolated cytoplasmic membrane vesicles. We conclude that a primary effect of this colicin involves the cytoplasmic membrane as a target.

Effect of carboxylate group modification on enzymatic and cardiotoxic properties of snake venom phospholipases A2

By treating Naja nigricollis and Naja naja atra phospholipase A2 with carbodiimide and semicarbazide, we obtained derivatives having varied numbers of modified carboxylate groups. When tested on artificial and natural substrates, derivatives of both enzymes with a modified carboxylate group at the active site (Asp-49) retained little enzymatic activity (1/41 to 10%). However, the derivatives of N. nigricollis also lost most of their lethal potency (5% of native), while those of N. n. atra retained considerable lethality (29%). Carboxyl modification with protection of Asp-49 in N. n. atra enzyme resulted in a derivative with lethal potency equal to or greater than the native enzyme and enzymatic activity which was low on all substrates (12-17% of native). Similar protection of Asp-49 at the active site in N. nigricollis enzyme produced a derivative with decreased enzymatic activity on artificial substrate (22% of native) and decreased lethality (17-33% of native), but with full enzymatic activity on natural substrates. When tested on electrical and mechanical properties of the isolated perfused heart and the isolated ventricle muscle wall, the derivatives of both enzymes retained considerably more of the cardiotoxic activity than would have been expected based on their residual enzymatic activity. The one exception occurred with the least modified N. nigricollis derivative which had an unaltered Asp-49, this enzyme retained both cardiotoxic activity and full enzymatic activity on natural substrates. The extent of phospholipid hydrolysis following treatment was measured in the isolated heart preparation and in hearts removed from mice following i.v. injection of the phospholipases. Very low levels of phospholipid hydrolysis were observed and no correlation could be made between the extent of hydrolysis and the pharmacological potencies of these enzymes. Modification of the enzymatic active site, whether of Asp-49 in this study of His-48 in prior studies, leads to a large decrease in both enzymatic activity and lethal potency. Asp and Glu residues outside of the enzymatic site contribute significantly to the lethal potency of the N. nigricollis enzyme and to the enzymatic activity of the N. n. atra enzyme. Based on these and previous data we conclude that changes in isoelectric points are not responsible for altered lethal potencies following chemical modification and that some pharmacological effects of snake venom phospholipases A2 are due to a non-enzymatic action, suggesting two distinct but perhaps overlapping active sites.

Dissociation of pharmacological and enzymatic activities of snake venom phospholipases A2 by modification of carboxylate groups

The carboxylate groups in an acidic and in a basic phospholipase A2 (PLA2) enzyme, purified, respectively, from Naja naja atra and Naja nigricollis snake venoms, were modified with carbodiimide and semicarbazide. The derivatives modified at pH 3.5 and pH 5.5 had less than 1% (N. nigricollis) or 2% (N. n. atra) residual enzymatic activity, whereas 12-16% enzymatic activity remained following modification at pH 5.5 in the presence of Ca2+. In marked contrast, these derivatives retained variable, but significantly greater, levels of lethal potency, hemolytic and anticoagulant activities, and abilities to block indirectly and directly induced contractions of the diaphragm. By this modification of aspartic and glutamic acid residues we have, for the first time, obtained derivatives of PLA2 which selectively retain greater pharmacological activity relative to enzymatic activity. Previously, we had found that modification of lysine and arginine residues produced derivatives which retain enzymatic activity but show a loss of pharmacological properties. These findings suggest that some pharmacological effects of snake venom PLA2 enzymes are due to a non-enzymatic action, suggesting two distinct but perhaps overlapping active sites.

Changes in lymphocyte response to phytohaemagglutinin and serum immunosuppressive activity after thermal injury

The present study consisted of two parts. In part one, 14 cases were divided into an invasive infection group (4 cases) and a non-invasive infection group (10 cases). A total of 68 assays for lymphocyte responses to PHA stimulation were carried out. The invasive infection group showed a significantly suppressed lymphocyte response, which occurred during invasive infection but neither before nor after the infection. The extent of third-degree burns was statistically significant between these two groups (P less than 0.05), but no significance was found between the total body surface area burned. In part two, 18 burn patients were studied for serum immunosuppressive activity. Both invasive infection cases and non-invasive infection cases showed serum immunosuppression during the course of the study and no significant difference was found between these two groups (P greater than 0.05). It is concluded that the extent of third-degree burn and the complicated systemic infection contribute to the impairment of lymphocyte responses to PHA stimulation, while the post-burn serum immunosuppression is unrelated to the occurrence of systemic infection.

Changes of serum amino acids in severely burned patients

The serum amino acids profile in ten severe burn patients was basically similar with the findings in major burns reported in our proceeding article, supporting the conclusion that burn patients might have a particular amino acid pattern. The larger was the burn size, the more severe was the nitrogen loss. Following a severe burn, the patient was faced with the challenge of acute protein malnutrition. After severe burns, the ratio of serum Phe/Tyr rose to a higher level than in the major burns. Moreover, the elevation of serum Met/Cys ratio indicated a more serious metabolic disturbance. During the first two weeks postburn, acute decrease of serum BCAA by 20-30 per cent of the normal value was associated with a striking increase of mortality. This fact indicated the level of BCAA might be of prognostic value. In severe burns, other than huge amount of calories and protein supplied, enriched BCAA, and perhaps, carnitine might be beneficial.

Effect of methylation of histidine-48 on some enzymatic and pharmacological activities of snake venom phospholipases A2

The effects on some pharmacological and enzymatic properties were determined following methylation of histidine at the enzymatic active site of the basic relatively toxic Naja nigricollis and the acidic relatively non-toxic Naja naja atra phospholipases A2. Following methylation a very low residual enzymatic activity (0.4-1% of control) was accompanied by a parallel loss in intraventricular lethality, anticoagulant potency, direct hemolytic action and ability to block directly and indirectly evoked contractions of the mouse phrenic nerve-diaphragm preparation. Since methylation does not impair the enzyme's ability to bind monomeric or micellar substrates or Ca2+, the results suggest that the pharmacologically active region of the molecule is different from the micellular substrate binding site but strongly influenced by the invariant histidine-48 located at the enzymatic active site.

Serum and erythrocyte amino acid pattern: studies on major burn cases

Venous serum amino acids were measured in 13 patients with major burns. Erythrocyte amino acids and plasma cortisol, blood sugar and urine catecholamine were measured in two representative subgroups respectively. After burn injury, serum proline, glycine, valine, isoleucine and arginine were significantly decreased; phenylalanine, cysteine, methionine, leucine, glutamate, alanine, aspartic acid and tyrosine were significantly increased. Histidine and lysine fluctuated. This serum amino acid profile is considered as a specific pattern for major burns. Serum phenylalanine was markedly elevated in the hypermetabolic burn patients, its fluctuation coincided with the burn course and was negatively correlated with serum albumin level (P less than 0.001). These findings suggest that the ratio of phenylalanine tyrosine is a useful clinical parameter for assessing the patient's nutritional condition. Twenty-three simultaneous determinations of both serum and erythrocyte amino acid concentrations show similar changes, suggesting that the serum amino acid profile might reflect the change of total free amino acid pool. After burn injury, plasma cortisol, blood sugar and urine catecholamine were elevated as well as urine urea nitrogen. However, although the first three returned to normal by the end of the second week post burn, urine urea nitrogen remained high. This indicates that there are other factors controlling nitrogen loss in patients with major burns, it is also postulated that, due to the abnormal amino acid pattern revealed after major burns, the constituents of commercially available amino acid solutions should be modified.

Rectal malacoplakia in a patient with Hodgkin's disease. Report of a case and review of the literature

A 37-year-old man was found to have classic malacoplakia of the rectum after three courses of chemotherapy for stage IV Hodgkin's disease. Sigmoidoscopy with excisional biopsy was performed because of rectal bleeding. The biopsy specimen of the rectal lesion showed focal extensive granulomatous changes with large macrophages containing round, dense Michaelis-Gutmann bodies. Electromicroscopy demonstrated calcifying spheres with laminated concertric structures (Michaelis-Gutmann bodies) and coliform bacillus in the cytoplasm of macrophages (Von Hansemann bodies). Review of the literature revealed that association of malacoplakia with Hodgkin's disease has never been documented, although it has been reported to be associated with conditions such as malignancy, organ transplantation, collagen disease, and leukemia. The possible role of immune disturbance as an underlying cause of malacoplakia is discussed.

Ethoxyformylation and guanidination of snake venom phospholipases A2: effects on enzymatic activity, lethality and some pharmacological properties

Lysine residues in the basic and relatively toxic N. nigricollis phospholipase A2 and in the acidic and relatively nontoxic N. n. atra phospholipase A2 were modified by acylation with ethoxyformic anhydride (in the presence or absence of the substrate dihexanoyl lecithin) or guanidination with O-methylisourea. Ethoxyformylation gave rise to some protein fractions in which enzymatic activity was preserved to a greater degree than intraventricular lethality. Guanidination had little effect on the isoelectric point or catalytic activity of either enzyme or on the lethal potency of the N. n. atra enzyme. However, the intraventricular lethality of the N. nigricollis enzyme was decreased much more than was its intravenous lethality, direct hemolytic potency, anticoagulant activity or cardiotoxic action on rat atrium. These results are compared to those previously obtained when the lysines in these two enzymes were carbamylated with potassium cyanate, a procedure which markedly decreased the isoelectric point of the enzymes. It is concluded that charge alone does not account for differences in toxicity. The data also indicate that there are at least two distinct active sites in both enzymes, one being primarily responsible for enzymatic activity and the other(s) associated with lethal and pharmacological effects of the protein. Modification of lysines affects the latter site(s), while having little or no effect on enzymatic activity.

Phospholipid hydrolysis in serum lipoproteins by a basic phospholipase A2 from Naja nigricollis snake venom and an acidic phospholipase A2 from Naja naja atra snake venom

Apparent Km and Vmax values for PC and PE hydrolysis were determined following exposure of HDL, LDL, and VLDL to a basic phospholipase A2 from N. nigricollis snake venom and an acidic phospholipase A2 from N. nigricollis snake venom and an acidic phospholipase A2 from N. n. atra snake venom. Both enzymes hydrolyzed the lipoprotein phospholipids approximately as fast as they hydrolyzed pure phospholipids in mixed micelles, however, the N. nigricollis enzyme, which has a much stronger anticoagulant effect than the N. n. atra enzyme, had lower apparent Vmax values. These values were highest for phospholipids in VLDL and lowest for HDL, however, the differences between the lipoproteins were relatively small with the N. nigricollis enzyme while the differences were much larger with the N. n. atra enzyme. Fractions of the two enzymes in which varying numbers of lysines were carbamylated showed much larger differences in relative rates of phospholipid hydrolysis in HDL, LDL and VLDL. Triton X-100 eliminates these differences in rates of hydrolysis. These results are discussed in terms of the differences in the organized structure of the lipoprotein classes and in the penetration ability of the phospholipases.

Production of deferriferrioxamines B and E from a ferroverdin-producing Streptomyces species

When Streptomyces sp. strain Wak. A-305 is cultured in iron (III)- or cobalt (II)-containing media, tris(p-vinylphenyl-4-hydroxy-3-nitrosobenzoato-N3, O4)ferrate(II) (ferroverdin) or the analogous tris-cobalt(III) complex, respectively, is produced intracellularly. In contrast, when cultured in transition metal ion-limiting media. Streptomyces sp. strain Wak. A-305 did not produce p-vinylphenyl 4-hydroxy-3-nitrosobenzoate (deferroferroverdin). Instead, deferriferrioxamines B and E, which have been characterized from other streptomycetes, were isolated extracellularly and may act as siderophores in this organism.U

Reversed unfolding-refolding process of cobra neurotoxin

Circular dichroism and nuclear magnetic resonance spectroscopies have been used to study the unfolding process of cobrotoxin upon addition of fluoro alcohols/or sodium dodecyl sulfate to its aqueous solution. In each final unfolded state, the protein had its disulfide bonds intact. The unfolding process has been found to be reversible in the case of fluoro alcohol/water mixtures, while no such reversibility was found in the case of sodium dodecyl sulfate. However, when hexafluoro-2-propanol is added to the sodium dodecyl sulfate unfolded protein, refolding is induced. The mechanism of unfolding is discussed in terms of the different interactions which govern the protein conformation in solution.

Mode of antibiotic action of 4-hydroxy-3-nitrosobenzaldehyde from Streptomyces viridans

The free ligand, deferroviridomycin A, and its iron(II) complex, viridomycin A, were detected in culture supernatant fluids of Streptomyces viridans 1671 and were structurally characterized as 4-hydroxy-3-nitrosobenzaldehyde and tris(4-hydroxy-3-nitrosobenzaldehydato-N3,O4)ferrate(II), respectively. We investigated the antibiotic activity of the above compounds and of the chemically synthesized bis copper(II), tris cobalt(III), and tris nickel(II) complexes against Escherichia coli NIHJ, Salmonella typhimurium LT-2Z, Staphylococcus aureus 209P, Streptococcus faecium 10541, and Bacillus cereus, T. The free ligand and its kinetically labile copper(II) and nickel(II) complexes displayed activity against all of the above organisms, whereas the kinetically inert iron(II) and cobalt(III) complexes displayed activity only against S. aureus and B. cereus. The antibiotic activity of the substitutionally labile metal complexes was attributed to dissociation of the free ligand. The mode of antibiotic action of the free ligand against E. coli appears to be interference with the structural and functional integrity of the cell membrane.

Crystallographic studies of snake venom proteins from Taiwan cobra (Naja nana atra). Cardiotoxin-analogue III and phospholipase A2

Orthorhombic crystals of cardiotoxin-analogue III from Taiwan cobra have been grown from 2-methyl-2,4-pentanediol solution. The space group is P222 with 2 molecules/asymmetric unit. Several different crystal forms of phospholipase A2 from Taiwan cobra have been produced with or without Ca2+ ion. One of them, grown from 30 mM sodium cacodylate buffer (pH 6 to 7) and 30% 2-methyl-2,4-pentanediol with 20 mg/ml of protein, diffracts well to 2 A resolution. It crystallizes in space group P3112 or P3212 with 2 molecules/asymmetric unit, but it can be related to a quasi-cubic space group P213.

Lack of correlation between anticoagulant activity and phospholipid hydrolysis by snake venom phospholipases A2

The anticoagulant effects and the simultaneous plasma phospholipid hydrolysis induced by three purified phospholipases obtained from snake venoms, i.e., the basic, relatively toxic N. nigricollis, the neutral, relatively nontoxic H. haemachatus, and the acidic, relatively nontoxic N. n. atra, have been compared. The N. nigricollis phospholipase has a very strong anticoagulant effect at concentrations which induce relatively low levels of phospholipid hydrolysis in plasma. The H. haemachatus and N. n. atra phospholipases become anticoagulant only at high concentrations, and the associated phospholipid hydrolysis is also very high. It is concluded that, while all phospholipases are likely to inhibit coagulation if used in amounts sufficiently large to deplete plasma of phospholipids, strongly active phospholipases, such as N. nigricollis, interfere nonenzymatically with the clotting process before any appreciable phospholipid hydrolysis is reached.