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Biomedical subjects

S A Weinstein

Publications and source records attributed to S A Weinstein.

At least 19 recordsLinked to original sources
PubMed1994

Properties of Duvernoy's secretions from opisthoglyphous and aglyphous colubrid snakes.

Relatively little attention has been given to the biological properties of Duvernoy's secretions produced by opisthoglyphous and some aglyphous colubrid snakes. A review is presented of literature pertaining to these secretions. Most detailed analyses of Duvernoy's secretions and their biological properties have been performed since the late 1970s. The dispholidines, Dispholidus typus and Thelotornis sp., and the natricines, Rhabdophis tigrinus and R. subminiata, have received the most attention due to the high toxicity of their secretions and their medical importance. These species produce secretions with variably strong prothrombin-activating activity, defibrinating activity, and hemorrhagic potential. Boigines, and natricines other than Rhabdophis, produce secretions of low to moderate toxicity and are variably hemorrhagic and proteolytic. Xenodontines and homalopsines similarly show hemorrhagic potential with low to moderate toxicity. Neurotoxic activity has been reported only from secretions of the boigines, Boiga blandingi and B. irregularis and the xenodontine, Heterodon platyrhinos. These species produce secretions containing postsynaptically acting components. Analyses of some of these secretions have shown that enzymes common to many ophidian venoms such as phospholipases A and L-amino acid oxidase are uncommon in the colubrid secretions studied. This may be due to few studies assaying for multiple enzyme activities and/or the unavailability of many secretion samples for study. Methods of secretion extraction, storage, and assay are discussed. Projected future research and the adaptive implications of Duvernoy's secretions are considered.

Animals↗
PubMed1992

Molecular properties and structure-function relationships of lethal peptides from venom of Wagler's pit viper, Trimeresurus wagleri.

Two new lethal peptides (waglerins) were purified from the venom of Trimeresurus wagleri, and sequenced. We found them to be analogs of lethal peptides (waglerins) I and II reported previously (Weinstein et al., Toxicon 29, 227-236, 1991), with an additional Ser-Leu on the amino terminus. Three of the four waglerins were synthesized and the products were chemically and biologically equivalent to the naturally occurring counterparts in venom. Murine i.p. LD50 for synthetic waglerins I, SL-I and II were 0.33, 0.22, and 0.51 mg/kg, respectively. The single, intramolecular disulfide bond in each synthetic peptide formed rapidly in high yield. The reduced (cysteine-containing) forms of the peptides appeared to have significant toxicities, even without prior disulfide bond formation, but synthetic analogs with serine substituted for cysteine were not toxic. The synthetic dimer of waglerin I, formed by two intermolecular disulfide bonds, was not toxic, but rapidly rearranged to lethal, monomeric waglerin I at alkaline pH upon the addition of 5 mM beta-mercaptoethanol. Waglerin I was inactivated by cleavage at Tyr-15 with chymotrypsin.

Amino Acid Sequence↗
PubMed1992

Pathologic changes induced by phospholipase A2 isolated from the venom of Collett's snake, Pseudechis colletti: a light and electron microscopic study.

Pseudechis colletti is an Australian elapid snake with a range limited to central Queensland, Australia. The venom of this snake, as well as that of several other Australian elapids, has been shown to contain a phospholipase A2 (PLA2) which can cause a marked myoglobinuria in mice. Few studies have described the histopathologic and ultrastructural changes that result from myotoxic PLA2-induced damage. Our investigation demonstrated that the isolated PLA2 induced myodegeneration and necrosis in myocardium in a dose-related manner, with subsequent myoglobinuria and myoglobinuric nephropathy.

Animals↗
PubMed1992

A novel peptide toxin from Trimeresurus wagleri acts pre- and post-synaptically to block transmission at the rat neuromuscular junction.

The neuromuscular effects of a peptide toxin (peptide I) from venom of Trimeresurus wagleri were investigated using the rat extensor digitorum longus muscle/peroneal nerve preparation. Sub-micromolar concentrations depressed endplate currents (EPCs) produced in response to nerve stimulation. Since quantal content of EPCs was not altered, it appears that the site of action is post-synaptic. However, higher concentrations (1.4-2.9 microM) also inhibited spontaneous release of transmitter. Nerve stimulation in the presence of peptide I caused 'rundown' of EPC amplitude, evidence that the peptide acts pre-synaptically to interfere with transmitter release. Recovery from this effect occurred within 3-5 min. of washing, but EPC amplitude took 20-30 min. to recover. The dual action of this peptide makes it unusual amongst naturally-occurring toxins, and these data suggest that further investigation of the peptide (and its analogues) could yield new information about neurotransmitter release.

Animals↗
PubMed1992

Analysis of tissue margins of cone biopsy specimens obtained with "cold knife," CO2 and Nd:YAG lasers and a radiofrequency surgical unit.

Analysis of the tissue margins of cone biopsy specimens obtained from 40 patients showed varying degrees of thermal and mechanical artifact at the tissue margins. The least artifact was seen in the tissue margins of specimens obtained with the scalpel ("cold knife"). The amount of thermal damage to biopsies obtained via lasers and the radiofrequency unit varied with the instrument employed. However, the quality of the tissue margins of specimens obtained using a radiofrequency surgical unit equipped with a needle electrode on a "pure cut" setting approached the quality of those obtained with the cold knife in their lack of thermal and mechanical artifact.

Biopsy, Needle↗
PubMed1991

Lethal potency and fractionation of Duvernoy's secretion from the brown tree snake, Boiga irregularis.

The liquid secretion contained only 15% protein and had relatively low proteolytic activity. The reconstituted crude secretion had a murine i.p. LD50 of 10.33 mg/kg and was not hemorrhagic in doses up to 200 micrograms. Fast Protein Liquid Chromatographic (FPLC) cation exchange analysis of reconstituted crude secretion resulted in resolution of 16 peaks. Lethal activity was identified in three peaks. The major lethal fraction was 12.5% of the secretion protein and had a murine i.p. LD50 of 7.3 mg/kg. A pooled fraction containing two lethal peaks which comprised 9.4% of secretion protein had moderate proteolytic activity and produced myoglobinuria in mice. The fraction had an approximate murine i.p. LD50 of 3.7 mg/kg. Microscopic examination of muscle tissue from mice succumbing to this fraction revealed multifocal myofiber degeneration and necrosis. SDS-PAGE indicated that the major lethal fraction contained three proteins with mol. wts of 12,500, 18,000 and 52,000 and the myotoxic fraction contained two proteins with mol. wts of 14,500 and 17,000. While B. irregularis Duvernoy's secretion has a low lethal index, it does contain a myotoxic fraction with moderate lethal potency. These observations and recent data describing clinical envenomation of several infant patients suggest that large specimens may pose a hazard to infants and small children.

Animals↗
PubMed1991

Characterization and amino acid sequences of two lethal peptides isolated from venom of Wagler's pit viper, Trimeresurus wagleri.

Two lethal toxins were isolated from Trimeresurus wagleri venom by fast protein liquid chromatography (molecular sieve) and high performance liquid chromatography (reverse phase). The toxins (termed peptide I and II) had mol. wt of 2504 and 2530, respectively, pIs of 9.6-9.9 and lacked phospholipase A, proteolytic, and hemolytic activity. Lethal peptide I had a murine i.p. LD50 of 0.369 mg/kg, while lethal II had a murine i.p. LD50 of 0.583 mg/kg. Peptide I retained full toxicity after autoclaving at 121 degrees C for 40 min. The lethal activity was found to represent less than 1% of the total venom protein, which was only 62-65% of crude venom. The amino acid sequence of peptide I revealed a proline-rich (over 30% of total sequence) sequence unique among snake venom toxins. Lethal peptide II showed the same sequence except for a second tyrosine in the position of histidine (residue No. 10) in peptide I. The toxin lacked antigenic identity with a number of representative neurotoxins and myotoxins. The crude venom shared at least one antigen with Crotalus scutulatus scutulatus venom. This antigen was not Mojave toxin. The toxin appears symptomatologically suggestive of a vasoactive peptide or neurotoxin.

Amino Acid Sequence↗
PubMed1991

Lethal toxins and cross-neutralization of venoms from the African water cobras, Boulengerina annulata annulata and Boulengerina christyi.

Venoms of the water cobras, Boulengerina, were assayed for lethality, proteolytic activity and protein content. Boulengerina annulata annulata and B. christyi venoms averaged 89% protein and lacked proteolytic activity. The murine i.p. LD50 of B. a. annulata and B. christyi venoms were 0.143 and 0.120 mg/kg, respectively. Polyvalent antivenom produced by the South African Institute of Medical Research neutralized 575 and 200 LD50 of B. a. annulata and B. christyi venoms/ml antivenom, respectively. Cation exchange chromatography resolved four lethal peaks from B. a. annulata venom and six lethal peaks from B. christyi venom. The major lethal peaks (about 12% of total venom protein) were purified further with molecular sieve chromatography and were characterized as 61 (B. a. annulata toxin) and 62 (B. christyi toxin) residue polypeptides with four half-cystines. Elucidation of the complete amino acid sequences indicated that these toxins belonged to the short-chain class of postsynaptic neurotoxins. Short-chain neurotoxins 1 from B. a. annulata and B. christyi had murine i.p. LD50 of 0.052 and 0.083 mg/kg, respectively, and showed over 80% homology with N. nigricollis alpha toxin. Reverse-phase analysis of another peak present in both venoms resolved a toxin that had an N-terminus identical to B. christyi short-chain neurotoxin 1. These fractions also contained toxins readily separable from the short-chain isotoxin by preparative reverse-phase chromatography. Amino acid sequencing of the first 28 residues indicated that both toxins were long-chain neurotoxins with identical N-termini. The LD50 of long-chain neurotoxins 2 from B. a. annulata and B. christyi venoms were 0.086 and 0.090 mg/kg, respectively. The venoms of these little-known elapids have the lowest LD50 of any African proteroglyph studied thus far and have high concentrations of potent postsynaptic neurotoxins.

Amino Acid Sequence↗
PubMed1991

Antibacterial effects of different snake venoms: purification and characterization of antibacterial proteins from Pseudechis australis (Australian king brown or mulga snake) venom.

Venoms from 30 different snake species were tested in a disc diffusion assay for antibacterial effects against gram-positive and gram-negative bacteria. A number of venoms gave a zone of inhibition against both groups of bacteria, including Aeromonas hydrophila, an important pathogen of reptiles and amphibians. Two antibacterial components from the venom of an Australian elapid, Pseudechis australis (Australian king brown or mulga snake) were purified to homogeneity. The proteins, designated LAO1 and LAO2, had potent antibacterial properties associated with L-amino acid oxidase activity. Both had native and subunit mol. wts of 142,000 and 56,000, respectively. Antibacterial activity correlated with enzymatic activity and was eliminated with catalase. LAO1 and LAO2 had 244 and 113 units of L-amino acid oxidase activity/mg protein, respectively. Compared to tetracycline, a drug of choice for Aeromonas infections in humans, reptiles and amphibians, the in vitro antibacterial effects of LAO1 and LAO2 were respectively 70 and 17.5 times more effective (on a molar basis).

Aeromonas hydrophila↗
PubMed1991

Facial thermography, basis, protocol, and clinical value.

Computerized electronic telethermography provides clinicians with a reliable evaluation of subtle body surface temperature changes that show underlying physical disorders characterized by pain. The first study population involved 4000 measurements of 100 volunteers at the Medical School of New Jersey. This study of normal volunteers evaluates the validity and reliability of using 0.5 degrees C skin surface temperature difference between opposite sides of the head as a minimum difference standard for recognition of a clinically significant thermographic abnormality. A second study population of over 300 patients with clinically suspected temporomandibular disorder were used. The authors used a standard thermographic protocol procedure that is approved by the Academy of Neuromuscular Thermography. Also discussed in detail are artifactual influences and trigger point detection. The clinical value of this information in the diagnosis and treatment of temporomandibular disorder patients is self evident.

Adult↗
PubMed1990

Preliminary fractionation of tiger rattlesnake (Crotalus tigris) venom.

Tiger rattlesnake (Crotalus tigris) venom was fractioned by using fast protein liquid chromatography (FPLC). The crude venom had low protease activity, lacked hemolytic activity and had an i.p. LD50 of 0.070 mg/kg for mice. Lethal fractions obtained by anion and cation exchange were examined for antigenic identity with crotoxin and Mojave toxin. Four toxins were obtained by anion exchange chromatography which showed immunoidentity with these toxins, and one fraction caused rear limb paresis in mice. A lethal toxin (about 10% of total venom protein) purified further with Superose-12 FPLC (molecular sieve) had an i.p. LD50 of 0.050 mg/kg for mice, reacted strongly with anti-crotoxin and anti-Mojave toxin antiserum in ELISA and immunoelectrophoresis. This toxin also showed complete immunoidentity with crotoxin and Mojave toxin in immunodiffusion assays with anti-crotoxin antiserum. The results indicated the presence of crotoxin and/or Mojave toxin isoforms in this venom. Although this species has a low venom yield (average 10 mg per snake), the venom is highly toxic and contains high concentrations of several neurotoxic isotoxins.

Animals↗
PubMed1990

Thermophysiologic anthropometry of the face in Homo sapiens.

Standard clinical thermographic practice has been to regard a side-to-side skin surface temperature difference of 0.5 degrees C or greater as indicative of a clinically significant disorder when such a difference is observed for the contralateral sides of the face. Prior to this time this standard relied upon empiric observation and cumulative experience. This paper provides the first published documentation clearly supportive of this long-standing clinical practice.

Cephalometry↗
PubMed1988

Isolation of a hemolysin from a spore-crystal mixture of Bacillus thuringiensis israelensis (serotype H-14).

A hemolytic toxin from Bacillus thuringiensis israelensis was obtained by alkaline extraction and fast protein liquid chromatography (chromatofocusing followed by gel filtration). The toxin displayed a pI of 4.6-4.8 and an Mr of 26,000. Amino acid analysis demonstrated large amounts of serine, glycine and glutamic acid. The toxin was strongly lytic for rabbit, human and non-human primate erythrocytes, and was weakly lytic toward equine, feline, canine, bovine, amphibian and reptilian erythrocytes. It was weakly entomocidal as indicated by a lethal potency (LC50) of 25 micrograms/ml for second instar larvae of Anopheles stephansi. Direct micro-ELISA indicated that the toxin lacked antigenic identity with numerous eukaryotic and prokaryotic toxins and venoms.

Amino Acids↗
PubMed1988

Kinetics of hemolysis induced by a toxin from Bacillus thuringiensis israelensis.

The kinetics of hemolysis resulting from the action on rabbit erythrocytes of a highly purified cytolytic toxin (26,000 mol. wt) isolated from a spore-crystal mixture of Bacillus thuringiensis israelensis was studied. Course of hemolysis, as determined by release of hemoglobin, yielded sigmoid curves whose maximum slopes were taken as a measure of the rate of lysis. Hemolysis occurred without an induction period, and the rate of lysis was a linear function of toxin concentration. Rate of hemolysis as a function of temperature yielded an Arrhenius constant of 9300 calories per mole. The toxin was active between pH 4.5 and 8.0. Lysis was strongly inhibited by Cu2+, Fe2+ and Zn2+ in concentrations as low as 0.025 M. Phosphatidylserine, phosphatidylinositol, phosphatidylcholine and sphingomyelin inhibited lysis, whereas phosphatidylethanolamine, cerebroside, cholesterol and major integral erythrocyte membrane proteins caused little or no inhibition. Inhibition of lysis by sucrose indicates that hemolysis is of the colloid-osmotic type.

Bacillus thuringiensis↗
PubMed1987

Isolation and characterization of a phospholipase B from venom of Collett's snake, Pseudechis colletti.

Phospholipase B in the venom of the Australian elapid snake, Pseudechis colletti, was purified to near homogeneity. By means of gel filtration it had an Mr of about 35,000, and by SDS-polyacrylamide gel electrophoresis an Mr of about 16,500. These presumably are dimeric and monomeric forms of the enzyme. It was isoelectric at pH 6.2 as compared to 7.8 for phospholipase A2 from which it was readily separated. It was relatively thermostable. As determined by release of water-soluble phosphorous, it degraded phosphatidylcholine and phosphatidylethanolamine, but did not degrade other phospholipids tested. The purified enzyme was strongly hemolytic in vitro for rabbit and human erythrocytes, but not for bovine or ovine erythrocytes. Hemolysis of rabbit erythrocytes gave rise to membranes showing ultrastructural changes that may be unique for this enzyme. The protein was highly active in producing turbidity in dilute solutions of egg yolk. It was cytotoxic for cultured rhabdomyosarcoma cells and was lethal for mice in which death was preceded by massive myoglobinuria.

Animals↗
PubMed1987

Nursing assessment program in infection control procedures.

To assess the infection control educational needs of the nursing service while providing a "hands-on" in-service exercise, nurses were invited to test their infection control knowledge as part of a clinical scenario. After a brief review of the "case," participants surveyed for 10 minutes a mock patient's room where a manikin served as the "patient." Through staged breaks in technique, various components of infection control practice were to be identified by the participants. Five basic areas of infection control practice including handwashing and isolation technique, Foley catheter care, intravenous therapy and line maintenance, use of suctioning equipment and fluids, and general sanitation were presented at 12 stations within the room. Immediately after this exercise, members of the infection control staff revealed the errors in the exhibit and demonstrated the correct procedures. The average score among 548 participants was 57% (11.4 out of 20 possible correct answers). Scores were not influenced by the number of years of experience in nursing. However, differences were seen regarding educational degree and nursing units, which served as a basis to recommend specific infection control education.

Antisepsis↗