A local neighborhood volunteer network improves response times for simulated cardiac arrest.

AIM: Each minute is crucial in the treatment of out-of-hospital cardiac arrest (CA). Immediate chest compressions and early defibrillation are keys to good outcomes. We hypothesized that a coordinated effort of alerting trained local neighborhood volunteers (vols) simultaneously with 911 activation of professional EMS providers would result in substantial decreases in call-to-arrival times, leading to earlier CPR and defibrillation. METHODS: We developed a program of simultaneously alerting CPR- and AED-trained neighborhood vols and the local EMS system for CA events in a retirement residential neighborhood in Southern Arizona, encompassing approximately 440 homes. The closest EMS station is 3.3 miles from this neighborhood. Within this neighborhood, 15 vols and the closest EMS station were involved in multiple days of mock CA notifications and responses. RESULTS: The two groups differed significantly in distance to the mock CA event and in response times. The volunteers averaged 0.3 ±â€¯0.2 miles from the mock CA incidences while the closest EMS station averaged 3.4 ±â€¯0.1 miles away (p < 0.0001). Response times (time from call to arrival) also differed. Two volunteers, one bringing an AED, averaged 1 min 38 s ±â€¯53 s in Phase 1, while it took the EMS service an average of 7 min 20 s ±â€¯1 min 13 s to arrive on scene; p < 0.0001. CONCLUSION: Local neighborhood volunteers were geographically closer and arrived significantly sooner at the mock CA scene than did the EMS service. The approximate time savings from call to arrival with the volunteers was 4-6 min.

Low-factor consumption for major surgery in haemophilia B with long-acting recombinant glycoPEGylated factor IX.

INTRODUCTION: Surgery in patients with haemophilia B carries a high risk of excessive bleeding and requires adequate haemostatic control until wound healing. Nonacog beta pegol, a long-acting recombinant glycoPEGylated factor IX (FIX), was used in the perioperative management of patients undergoing major surgery. AIM: To evaluate the efficacy and safety of nonacog beta pegol in patients with haemophilia B who undergo major surgery. METHODS: This was an open-label, multicentre, non-controlled surgery trial aimed at assessing peri- and postoperative efficacy and safety of nonacog beta pegol in 13 previously treated patients with haemophilia B. All patients received a preoperative nonacog beta pegol bolus injection of 80 IU kg-1 . Postoperatively, the patients received fixed nonacog beta pegol doses of 40 IU kg-1 , repeated at the investigator's discretion. Safety assessments included monitoring of immunogenicity and adverse events. RESULTS: Intraoperative haemostatic effect was rated 'excellent' or 'good' in all 13 cases. Apart from the preoperative injection, none of the patients needed additional doses of nonacog beta pegol on the day of surgery. The median number of postoperative doses of nonacog beta pegol was 2.0 from days 1 to 6 and 1.5 from days 7 to 13. No unexpected intra- or postoperative complications were observed including deaths or thromboembolic events. No patients developed inhibitors. CONCLUSIONS: These results indicated that nonacog beta pegol was safe and effective in the perioperative setting, allowing major surgical interventions in patients with haemophilia B with minimal peri- and postoperative concentrate consumption and infrequent injections as reported with standard FIX products.

Recombinant long-acting glycoPEGylated factor IX (nonacog beta pegol) in haemophilia B: assessment of target joints in multinational phase 3 clinical trials.

BACKGROUND: The paradigm(™) 2 and 4 phase 3 clinical trials investigated the safety and efficacy of nonacog beta pegol, a recombinant glycoPEGylated factor IX (FIX) with extended half-life, in previously treated haemophilia B patients. AIM: These post hoc analyses investigated the bleeding patterns in target joints. METHODS: Patients randomized to 40 or 10 IU kg(-1) once weekly prophylaxis who had at least one target joint were included. Baseline demographics and disease-specific data were collected. Bleeding patterns were assessed, and an International Society on Thrombosis and Haemostasis (ISTH) definition of target joints was used. RESULTS: A total of 67% and 8% of patients in the 40 and 10 IU kg(-1) arm, respectively, did not experience target joint bleeds during the paradigm(™) 2 trial. Twenty-four target joints were recorded in each prophylaxis arm at baseline. During the paradigm(™) 2 trial, no bleeds were reported in 17 (71%) and 7 (29%) target joints in the 40 and 10 IU kg(-1) arms respectively. All target joint bleeds in the 40 IU kg(-1) once weekly prophylaxis arm were controlled with a single injection of 40 IU kg(-1) nonacog beta pegol. By the latest ISTH definition, 90% and 58% of target joints in the 40 and 10 IU kg(-1) arms, respectively, were no longer considered target joints at the end of the paradigm(™) 2 trial. At the end of the paradigm(™) 4 extension trial, all target joints in the 40 IU kg(-1) arm were no longer considered target joints. CONCLUSION: Routine prophylaxis with 40 IU kg(-1) once weekly nonacog beta pegol has the potential for effective management of target joint bleeds in haemophilia B patients.

Population pharmacokinetic modeling for dose setting of nonacog beta pegol (N9-GP), a glycoPEGylated recombinant factor IX.

BACKGROUND: nonacog beta pegol (N9-GP) is a glycoPEGylated recombinant factor IX (rFIX) molecule with a prolonged half-life. OBJECTIVES: To provide information on potential dose regimens for N9-GP for phase 3 pivotal and surgery trials. METHODS: A population pharmacokinetic model was developed from single-dose data derived from the first human-dose trial with N9-GP in hemophilia B patients, and was used to extrapolate to steady-state conditions for different N9-GP dose regimens for prophylaxis. The model was also used to compare prophylaxis using N9-GP with standard prophylactic regimens using rFIX or plasma-derived (pd) FIX (40 IU kg(-1) every third day). Plasma activity following dosing with N9-GP, rFIX and pdFIX for surgery and on-demand treatment of bleeds was also simulated. RESULTS: A linear two-compartmental model best described the pharmacokinetic profiles of N9-GP, rFIX and pdFIX. A prophylactic regimen of 10 U kg(-1) N9-GP once weekly predicted mean peak and trough levels of 18 and 4.2 U dL(-1) , while 40 U kg(-1) once weekly predicted values of 72 and 17 U dL(-1) , respectively. Standard prophylactic regimens with rFIX and pdFIX predicted mean peak and trough levels of 34 and 3.9 IU dL(-1) for rFIX, and mean values of 43 and 2.1 IU dL(-1) for pdFIX. Additional simulations predicted significantly reduced dosing frequency and factor concentrate consumption for N9-GP vs. rFIX and pdFIX for surgery and the treatment of bleeds. CONCLUSIONS: N9-GP may allow prophylaxis, surgical dosing regimens and on-demand treatment of bleeding episodes with less frequent injections and lower factor concentrate consumption; this possibility is being investigated in prospective clinical trials.

A comparison of intranasal fentanyl spray with oral transmucosal fentanyl citrate for the treatment of breakthrough cancer pain: an open-label, randomised, crossover trial.

OBJECTIVE: The efficacy of intranasal fentanyl spray (INFS) was compared with that of oral transmucosal fentanyl citrate (OTFC) for the relief of cancer-related breakthrough pain (BTP) in an open-label, crossover trial. METHODS: Adult cancer patients receiving stable background opioid treatment and experiencing BTP episodes were recruited from 44 study centres in seven European countries (Austria, France, Germany, Italy, Poland, Spain and the United Kingdom); of the 196 patients enrolled, 139 were randomised to receive INFS followed by OTFC, or vice versa. Patients were titrated to an effective dose of one agent (50, 100 or 200 microg INFS; 200, 400, 600, 800, 1200 or 1600 microg OTFC) to treat six BTP episodes, then titration and treatment were repeated with the other agent. The primary outcome was patient-recorded time to onset of 'meaningful' pain relief. Secondary outcomes included pain intensity difference (PID) at 10 and 30 minutes (PID(10), PID(30)), sum of PID at 15 and 60 minutes (SPID(0-15), SPID(0-60)), ease of administration, treatment preference and relationship between background opioid dose and effective INFS dose. Additional outcome measures included proportions of episodes with > or =33% and > or =50% pain intensity (PI) reduction, and PID at additional time points. CLINICAL TRIAL REGISTRATION NUMBER: NCT00496392. RESULTS: Among the intention-to-treat population (n = 139), median time to onset of 'meaningful' pain relief was 11 minutes with INFS versus 16 minutes with OTFC; 65.7% of patients attained faster time to 'meaningful' pain-relief onset with INFS (p < 0.001). PID was statistically significantly greater for INFS than OTFC from 5 minutes post-dosing. Significantly more INFS-treated breakthrough pain episodes achieved clinically important pain relief (> or =33% and > or =50% PI reduction) up to 30 minutes post-dosing. The proportions of episodes treated with INFS and OTFC achieving a PI reduction of > or =33% at 5 minutes were 25.3% versus 6.8% (p < 0.001), and at 10 minutes were 51.0% versus 23.6% (p < 0.001), respectively; the proportions of episodes treated with INFS and OTFC achieving a > or =50% PI reduction at 5 minutes were 12.8% versus 2.1% (p < 0.001), and at 10 minutes were 36.9% versus 9.7% (p < 0.001), respectively. Higher SPID(0-15) and SPID(0-60) scores were achieved with INFS (p < 0.001). More patients preferred INFS than OTFC (p < 0.001) and more patients found it very easy/easy to use. Both treatments were well tolerated. In the safety population (n = 139), 56.8% (n = 79) of patients experienced > or =1 AE during the trial. The only AE that occurred in > or =5% of patients in either treatment group was nausea. Among those patients who experienced serious AEs (13.7%, n = 19), none were considered to be related to either study medication. There was a weak correlation between effective INFS doses and background opioid doses. CONCLUSION: In this open-label, randomised, crossover trial, significantly more patients attained faster 'meaningful' pain relief with INFS than OTFC, and more patients preferred INFS to OTFC.

Measurement of spin-correlation parameters ANN, ASS, and ASL at 2.1 GeV in proton-proton elastic scattering.

At the Cooler Synchrotron COSY/Jülich spin-correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for A(NN), A(SS), and A(SL) for c.m. scattering angles between 30 degrees and 90 degrees. Our data on A(SS)--the first measurement of this observable above 800 MeV--clearly disagrees with predictions of available pp scattering phase-shift solutions while A(NN) and A(SL) are reproduced reasonably well. We show that in the direct reconstruction of the scattering amplitudes from the body of available pp elastic scattering data at 2.1 GeV the number of possible solutions is considerably reduced.

Excitation functions of the analyzing power in pp--> scattering from 0.45 to 2.5 GeV

Excitation functions A(N)(p(p),Theta(c.m.)) of the analyzing power in pp--> elastic scattering have been measured with a polarized atomic hydrogen target for projectile momenta p(p) between 1000 and 3300 MeV/ c. The experiment was performed for scattering angles 30 degrees

Isolation, characterization and crystallization of a phospholipase A2 myotoxin from the venom of the prairie rattlesnake (Crotalus viridis viridis).

A myotoxin with phospholipase A2 (PLA2) activity was isolated from the venom of the prairie rattlesnake (Crotalus viridis viridis, CVV) by cation-exchange chromatography. The toxin contains 123 amino acids and has an estimated mol. wt of 14,000. It is basic, with a pI above 9. Comparison of the N-terminal 33 residues of this myotoxin with other PLA2 proteins from snake venoms showed that CVV myotoxin has highest homology (91%) to one isoform of the B component of crotoxin from Crotalus durissus terrificus venom, and less homology (73-75%) to mojave toxin from Crotalus scutulatus scutulatus venom and agkistrotoxin from Agkistrodon halys Pallas venom. It has the least homology (40-43%) to PLA2s from venom of two other snakes in the Crotalus genus which are neither neurotoxic nor myotoxic. CVV myotoxin induces the type of myonecrosis typical of snake venom myotoxins with the PLA2 structure, i.e. rapid disruption of the plasma membrane as indicated by the presence of delta lesions, hypercontraction and clumping of the myofilaments, and necrosis of affected skeletal muscle cells. Inhibition of the phospholipase activity of the toxin with p-bromophenacyl bromide inhibits the myotoxic activity, indicating that for some myotoxins with the PLA2 structure, the catalytic activity is important for myotoxic activity. This is the first report of the isolation of a non-neurotoxic, single-chain PLA2 myotoxin from the venom of a snake from the Crotalus genus.

Presence of heat-stable hemorrhagic toxins in snake venoms.

Twenty-eight snake venoms (seven Agkistrodon venoms, six Bothrops venoms, 13 Crotalus venoms, one Sistrurus venom, and one Bitis venom) were examined for the presence of heat-stable (100 degrees C, 5 min) hemorrhagic toxins. Both heated and unheated venoms were analyzed for their protein composition by SDS-PAGE, and tested for their hemorrhagic activity in vivo in mice and for their proteolytic activity on two different substrates. Heating all venoms led to the denaturation and loss of some proteins; however, most of the venoms retained a significant number of proteins. Seventeen venoms contained more than seven proteins after heating, whereas five venoms contained only one to three proteins. All but nine of the heated venoms had substantial hemorrhagic activity, and Agkistrodon piscivorus piscivorus venom had very high activity, almost four times that of the second most hemorrhagic venom from Crotalus viridis lutosus. Most venoms, heated or unheated, had activity on the two protease substrates. Using succinylated casein as the substrate, there was a wide range of activity, and heating drastically reduced the activity of all venoms except that of Crotalus ruber and Crotalus molossus molossus. With azocoll as substrate, all but two of the unheated venoms (Crotalus adamanteus and Crotalus viridis concolor) had very high activity, whereas upon heating, all except five venoms lost essentially all of their activity. Heated venoms from snakes in the Agkistrodon genus (except for Agkistrodon blomhoffi blomhoffi, an Asian snake) retained activity on azocoll, and this activity tended to correlate better with hemorrhagic activity of the venom than did proteolytic activity on casein.

A simple and rapid method for isolating small myotoxins from rattlesnake venoms.

Many rattlesnake venoms (family Crotalidae) contain small, highly basic toxins which cause contracture and necrosis of skeletal muscle in experimental animals. Isolation of these myotoxins requires several chromatographic steps taking several days to complete. We report the isolation of crotamine, myotoxin a, and myotoxin a-like molecules from whole venom of three species of rattlesnakes using a Hydrazide Avidchrom Cartridge. Milligram amounts of highly purified and biologically active myotoxin can be obtained in 30 min to 2 hr.

Cross-reactivities of monoclonal antibodies to a myotoxin from the venom of the broad-banded copperhead (Agkistrodon contortrix laticinctus).

A panel of murine monoclonal antibodies (MAbs) specific for a 14,500 mol. wt myotoxin of Agkistrodon contortrix laticinctus (broad-banded copperhead) venom was produced by cell fusion using the purified toxin as immunogen. The MAbs were used in immunoblotting and ELISA experiments to determine their immunological cross-reactivities. The three MAbs used in this study showed different immunoblotting and ELISA patterns when they were tested against 43 related and unrelated venom samples, indicating that they are specific for three different epitopes. MAb-42a specifically reacted with 50% of Agkistrodon venoms tested without cross-reacting with venoms of closely related species. This MAb reacted with venoms collected from Agkistrodon specimens from Florida, Kansas and Texas, but did not react with those from Louisiana, South Carolina, Ohio, New York or Mexico. MAb-6a showed similar reactivity but did react with venoms of snakes from Mexico. These results clearly indicate a geographical variation of the epitopes present in the myotoxin. Another antibody, MAb-18a, recognized an epitope present in the 14,500 mol. wt protein of all Agkistrodon venoms tested, but also reacted weakly with non-14,500 proteins from some Crotalus and Bothrops venoms tested. Both MAb-6a and MAb-18a neutralized the toxin-induced myonecrosis, but MAb-42a did not. Based on these results, the 14,500 mol. wt protein could serve as a general marker for venoms from snakes in the genus Agkistrodon found in North America.

Cardiotoxin 1 from cobra (Naja naja atra) venom causes necrosis of skeletal muscle in vivo.

Cardiotoxin 1 from cobra (Naja naja atra) venom was tested for its ability to cause necrosis of skeletal muscle cells after i.m. injection into mice. Light and electron microscopic examination of tissue indicated that the toxin caused necrosis of skeletal muscle as early as 30 min after injection. The plasma membranes of affected cells were ruptured in the area of delta lesions, and the myofibrils were condensed into dense clumps alternating with clear areas containing elements of the sarcotubular system and damaged mitochondria. By 24 hr the affected cells appeared as empty 'bags' containing only remnants of myofibrils and swollen mitochondria. To eliminate the possibility that the necrosis was due to contaminating phospholipase A2 (PLA2) activity of the sample, the sample was treated with p-bromophenacyl bromide (p-BPB), a known inhibitor of PLA2 activity. The p-BPB-treated preparation caused myonecrosis in vivo in mice, and the treatment caused a significant decrease in the release of fatty acids and no detectable lysophospholipid in human muscle cell cultures treated in vitro with the preparation, indicating the lack of PLA2 activity. Additionally, purified PLA2 from the same venom failed to cause myonecrosis in vivo at doses equal to or ten times the estimated contaminating concentration. Thus, it is concluded that cardiotoxin 1 from Naja naja atra venom causes necrosis of skeletal muscle cells in vivo upon i.m. injection.

Purification and characterization of two high molecular weight hemorrhagic toxins from Crotalus viridis viridis venom using monoclonal antibodies.

Two high mol. wt hemorrhagic toxins were purified from Crotalus viridis viridis venom using HPLC anion exchange and monoclonal antibody affinity chromatography following initial separation by HPLC with a preparative DEAE column. The fraction from the initial column having the highest hemorrhagic activity was used to immunize BALB/c mice for production of monoclonal antibodies. One of the monoclonal antibodies specifically recognized a single protein band of the immunizing fraction in native polyacrylamide gel electrophoresis. This monoclonal antibody was purified and conjugated to activated membranes for affinity purification of the antigen from the hemorrhagic fraction. Proteins eluted from the affinity membranes showed three bands in SDS-PAGE with apparent mol. wts of 68,000, 62,000 and 30,000. The 68,000 and 62,000 mol. wt proteins were further purified using an analytical DEAE column, and purity was demonstrated by the presence of a single band in SDS-PAGE and a single precipitation arc against antibodies to Crotalus viridis viridis venom in immunoelectrophoresis. The 68,000 (pI of 8.5) and 62,000 (pI of 4.1) proteins are highly hemorrhagic metalloproteinases which cleave N,N-dimethylcasein and fibrinogen. Both are glycoproteins with the same galactose-beta (1-4)-N-acetylglucosamine side-chains linked to asparagine residues. Treatment of both toxins with glycosidase F blocked their hemorrhagic activities. Oxidation of the sugar moieties by periodate inhibited the hemorrhagic activity of the 62,000 toxin, but not of the 68,000 mol. wt toxin.

Comparison of the immunogenicity and antigenic composition of several venoms of snakes in the family Crotalidae.

Crude venoms from the prairie rattlesnake (Crotalus viridis viridis), the western diamondback rattlesnake (Crotalus atrox), the eastern diamondback rattlesnake (Crotalus adamanteus) and the timber rattlesnake (Crotalus horridus horridus) were used to prepare monovalent antivenoms in rabbits. Each of these four monovalent antivenoms was reacted against six different venoms using the technique of immunoblotting (Western blot) to determine the relative immunogenicity of the four venoms and to compare the antigenic composition of six venoms. In addition to the four venoms listed above, venoms from the South American rattlesnake (Crotalus durissus terrificus) and the fer-de-lance (Bothrops atrox) were tested. SDS-PAGE showed that C. v. viridis venom contains the greatest number of components with 20, and the greatest number (7) less than 15,000 in mol. wt. C. durissus terrificus venom contains the least number of components, having 11. Immunoblotting experiments showed that the greatest reaction between venom and antivenom is not always obtained with the homologous system although the two greatest reactions obtained in this study were for two homologous reactions: that between monovalent anti-C. v. viridis venom and C. v. viridis venom, and that between monovalent anti-C. atrox venom and C. atrox venom. For antivenoms made to C. h. horridus and C. adamanteus venoms, the greatest reaction was obtained with C. atrox venom. There appeared to be no difference in immunogenicity between high-medium mol. wt (greater than 15,000) components and low mol. wt (less than 15,000) components in all systems tested except for C. atrox venom where two low mol. wt components gave a stronger reaction with the antivenom than would have been predicted based on their relative content in the venom as indicated by SDS-PAGE. If the immunoblots are scanned with a densitometer, both the qualitative (number of bands) and the quantitative (density of bands) reactions between venom and antivenoms can be taken into consideration by using a Reactivity Index (number of bands x density of bands). By comparing Reactivity Indexes of the various reactions obtained, the most cross-reactive antivenom tested was the monovalent antivenom to C. v. viridis venom, followed by anti-C. adamanteus, anti-C. atrox and anti-C. h. horridus in order of decreasing reactivity. The Reactivity Index can also be used to estimate the reactivity of a single antivenom with different venoms. The major limitation of this approach is the difficulty in standardizing the detection procedure using silver enhanced Protein A gold.

Classification of myonecrosis induced by snake venoms: venoms from the prairie rattlesnake (Crotalus viridis viridis), western diamondback rattlesnake (Crotalus atrox) and the Indian cobra (Naja naja naja).

The pathogenesis of myonecrosis induced by three different snake venoms was studied by light microscopic examination of skeletal muscle tissue taken at time periods ranging from 0.25 hr to 4 weeks after an intramuscular injection of the venom into mice. It was possible to identify different types of myonecrosis based on the abnormal morphologic states of the damaged cells. The types of myonecrosis observed correlated with the types of components present in the venom injected. Venoms containing direct acting toxins such as myotoxin a or phospholipase A2 induced specific types of myonecrosis. Also, venoms containing hemorrhagic toxins produced a type of myonecrosis similar to that induced by pure hemorrhagic toxins. The pathogenesis of each type of myonecrosis could be divided into the same four phases based on the pathologic states of the affected cells and the time after injection. During the 'early phase' (0.25-3 hr) affected muscle cells were in several different pathologic states reflecting the types of components present in the venom injected. During the 'intermediate phase' (6-24 hr) the pathologic state of the damaged cells had changed and depending on the venom new states might be present. By the 'late phase' (48-96 hr) all damaged cells have reached a common pathologic state of necrosis. The 'final phase' (1-4 weeks) is characterized by regeneration (partial or complete) of muscle cells. Although the number of different types of myonecrosis depended on the type of venom injected, i.e. Naja naja naja venom produced only two different types whereas Crotalus atrox venom produced at least four different types, cells of each tpe of myonecrosis progressed through the same four phases. In studies of the myotoxicity of snake venoms it is important to examine tissues taken during the early and intermediate phases to obtain accurate and useful information on the types of myonecrosis caused by the venom.

Characterization of the biological and immunological properties of fractions of prairie rattlesnake (Crotalus viridis viridis) venom.

Prairie rattlesnake (Crotalus viridis viridis) venom was separated using liquid column chromatography. The fractions were tested for biological activity in mice and for immunological reactivity against polyvalent (Crotalidae) antivenom and a monovalent antivenom to the crude venom. Several of the basic fractions and most of the non-basic fractions had hemorrhagic activity. Six of eight basic fractions had direct myotoxic activity, two of the basic fractions. Monovalent antivenom formed multiple precipitin bands with almost all of the fractions. These results clearly demonstrate that most of the venom components are antigenic and immunogenic. Immunodiffusion using the monovalent antivenom demonstrated that C. v. viridis venom contains many antigens common to 10 other crotaline venoms. One of the hemorrhagic components was present in five of the other venoms tested, one of the direct myotoxic components was present in three other venoms, and one of the lethal components was common to two other venoms. Another highly active hemorrhagic component was common to all of the venoms tested except that of Trimeresurus flavoviridis.

In vivo ability of antimyotoxin a serum plus polyvalent (Crotalidae) antivenom to neutralize prairie rattlesnake (Crotalus viridis viridis) venom.

A mixture of antimyotoxin a serum and polyvalent (Crotalidae) antivenom was injected i.v. in mice either 5 min before or 5 min, 30 min, 1 hr or 3 hr after i.m. injection of venom. Neutralization of the local myotoxicity of a sublethal dose (1.5 micrograms/g) of C. v. viridis venom occurred if the antisera were injected 5 min before or 5 or 30 min after venom, but not if injected 1 or 3 hr after the venom. Hemorrhage was neutralized when the mixture was injected either 5 min before or 5 min after injection of venom, but not when injected 30 min after injection of venom. Previous results showed that the mixture of antisera neutralized the same amount of venom (1.5 micrograms/g) when mixed with the venom prior to injection. Thus it is not possible with these two antisera to neutralize myonecrosis if the time interval between injections is greater than 30 min.

Ability of polyvalent (Crotalidae) antivenom to neutralize local myonecrosis induced by Crotalus atrox venom.

Wyeth's polyvalent (Crotalidae) antivenom was tested in mice for its ability to neutralize local myonecrosis induced by crude Crotalus atrox venom. A light microscopic assay was used to quantitate myonecrosis after i.m. injection of antivenom-venom mixtures. The results indicate that antivenom neutralizes the local myotoxicity of up to 15 micrograms venom per g body weight of mice. This neutralization is significantly better than that previously reported for Crotalus viridis viridis venom.

Ability of a mixture of antimyotoxin a serum and polyvalent (Crotalidae) antivenin to neutralize myonecrosis, hemorrhage and lethality induced by prairie rattlesnake (Crotalus viridis viridis) venom.

Mixtures containing polyvalent (Crotalidae) antivenin and antimyotoxin a serum were tested for their ability to neutralize the myotoxic, hemorrhagic and lethal activities of crude C. v. viridis venom when mixed with the venom prior to injection into white mice. A light microscopic method was used to measure the local myotoxic activity of the venom, i.e. myonecrosis index. The results show that the neutralizing ability of a 1:1 mixture of antisera for myonecrosis was 16 times that of antimyotoxin a serum alone and 63 times that of antivenin alone. There was no difference in neutralizing ability of the three ratios (2:1, 1:1, 1:2) of antivenin: antimyotoxin serum tested. Hemorrhage was measured by a new method in which the amount of hemoglobin in a muscle extract was measured after i.m. injection of test solution. The results show that the ability of a 1:1 mixture to neutralize hemorrhage was comparable to that of antivenin alone. There was no difference in hemorrhage neutralizing ability of the three ratios tested. In its ability to neutralize lethality, the 1:1 mixture was again comparable to antivenin. However, when the three different ratios of antisera were tested for neutralization of lethality the 2:1 and 1:1 ratios were as effective as antivenin alone, whereas the 1:2 ratio (antivenin: antimyotoxin serum) was less effective than antivenin alone. Thus the addition of antimyotoxin a serum to antivenin in equal proportions greatly improves the neutralization of the myotoxic activity of C. v. viridis venom and does not decrease the ability of antivenin to neutralize hemorrhage and lethality.

A new method for quantitating hemorrhage induced by rattlesnake venoms: ability of polyvalent antivenom to neutralize hemorrhagic activity.

Polyvalent (Crotalidae) antivenin was tested for its ability to neutralize the hemorrhagic activity of two crotaline venoms when mixed with them prior to injection. Hemorrhage was measured by two methods. In the first method an intradermal injection of venom produced a hemorrhagic spot which was quantitated by measuring diameters. In the second method the amount of hemoglobin in a muscle extract was measured after i.m. injection of venom. The results show that both methods are useful for quantitating hemorrhage induced by Crotalus viridis viridis and Crotalus atrox venoms. Antivenin neutralized the hemorrhagic activity of 240 micrograms C. v. viridis venom and 120 micrograms C. atrox venom per 0.05 ml. The question remains, can antivenin neutralize this amount of venom when injected independently of venom.