Vitamin E supplementation of newly arrived feedlot calves.

Seven hundred fifteen crossbred (primarily British) calves purchased in southern Oklahoma and northern Texas auction barns were received at the Willard Sparks Beef Research Center, Stillwater, OK, and used to study effects of duration (days) of vitamin E feeding during a 42-d receiving period on animal performance, health, and serum cholesterol and vitamin E concentrations. Upon arrival, calves were blocked by load (seven loads), sorted by BW (light, n = 4 pens per load; and heavy, n = 4 pens per load), and assigned randomly to one of four dietary treatments (n = 2 pens per load; 14 pens per treatment). Experimental diets were formulated to provide 2,000 IU.calf(-1).d(-1) of supplemental vitamin E (dl-alpha-tocopherol acetate) for 0 (CON), 7 (E7), 14 (E14), or 28 (E28) d. Vitamin E was delivered in a pelleted supplement that was added to the basal diet in decreasing concentrations as DMI increased (2.0 kg of DMI = 6%; 4.0 kg of DMI = 4%; and 6.0 kg of DMI = 2%). Serum samples were collected on d 0, 14, 28, and 42 for determination of cholesterol, alpha-tocopherol (d 0, 28, and 42), and antibody (IgG) concentrations. Duration of vitamin E supplementation did not affect ADG (0.98 kg/d; P = 0.56) or G:F (0.189; P = 0.87). Serum cholesterol concentrations decreased (day effect; P < 0.001) for all treatments from d 0 (average = 127 mg/100 mL) to 14 (average = 62 mg/100 mL). Serum alpha-tocopherol decreased (day effect; P < 0.001) from d 0 (5.2 microg/mL) to 28 (1.8 microg/mL); however, on d 28, a greater (P < 0.001) serum alpha-tocopherol concentration was observed for E28 (3.4 microg/mL) calves than for CON (1.1 microg/mL), E7 (1.2 microg/mL), or E14 (1.5 microg/mL) calves. Respiratory disease was diagnosed in 64.6% of calves in this study. Medical costs were less (P = 0.08) for calves fed vitamin E for 28 d (4.88 dollars/calf) than for calves fed the control diet (6.29 dollars/calf). Carcass characteristics were not affected (P = 0.19 to 0.88) by dietary treatments. Supplemental vitamin E formulated for 2,000 IU.calf(-1).d(-1) had little influence on performance and overall health status of calves under our experimental conditions; however, the increased serum concentrations of alpha-tocopherol when vitamin E was fed for 28 d suggests that any potential effects of vitamin E on health status might be time-dependent.

Lycopene from two food sources does not affect antioxidant or cholesterol status of middle-aged adults.

BACKGROUND: Epidemiological studies have reported associations between reduced cardiovascular disease and diets rich in tomato and/or lycopene. Intervention studies have shown that lycopene-containing foods may reduce cholesterol levels and lipid peroxidation, factors implicated in the initiation of cardiovascular disease. The objective of this study was to determine whether consumption of lycopene rich foods conferred cardiovascular protection to middle-aged adults as indicated by plasma lipid concentrations and measures of ex vivo antioxidants. METHODS: Ten healthy men and women consumed a low lycopene diet with no added lycopene (control treatment) or supplemented with watermelon or tomato juice each containing 20 mg lycopene. Subjects consumed each treatment for three weeks in a crossover design. Plasma, collected weekly was analyzed for total cholesterol, high density lipoprotein cholesterol (HDL-C) and triglyceride concentrations and for the antioxidant biomarkers of malondialdehyde formation products (MDA), plasma glutathione peroxidase (GPX) and ferric reducing ability of plasma (FRAP). Data were analyzed using Proc Mixed Procedure and associations between antioxidant and lipid measures were identified by Pearson's product moment correlation analysis. RESULTS: Compared to the control diet, the lycopene-containing foods did not affect plasma lipid concentrations or antioxidant biomarkers. Women had higher total cholesterol, HDL-C and triglyceride concentrations than did the men. Total cholesterol was positively correlated to MDA and FRAP while HDL-C was positively correlated to MDA and GPX. GPX was negatively correlated to triglyceride concentration. CONCLUSIONS: The inclusion of watermelon or tomato juice containing 20 mg lycopene did not affect plasma lipid concentrations or antioxidant status of healthy subjects. However, plasma cholesterol levels impacted the results of MDA and FRAP antioxidant tests.

Seroprevalence of antibodies to Sarcocystis neurona in equids residing in Oklahoma.

A sampling of equids from the state of Oklahoma produced an estimate of seroprevalence of antibody to Sarcocystis neurona to be about 89.2%. This figure represents the highest currently reported regional seroprevalence of antibody to this organism. Regional differences in seroprevalence were found in the western quadrants of the state relative to the eastern quadrants of the state, with a significantly higher seroprevalence in the eastern regions. Thoroughbreds were found to exhibit a statistically significant lower seroprevalence as a breed group when compared with other breeds sampled.

Vaccination of cattle with Anaplasma marginale derived from tick cell culture and bovine erythrocytes followed by challenge-exposure with infected ticks.

Anaplasmosis, a hemolytic disease of cattle caused by the tick-borne pathogen Anaplasma marginale (Rickettsiales: Anaplasmataceae) has been controlled using killed vaccines made with antigen harvested from infected bovine erythrocytes. We recently developed a cell culture system for propagation of A. marginale in a continuous tick cell line. In this study, we performed a cattle trial to compare the bovine response to vaccination with A. marginale harvested from tick cell culture or bovine erythrocytes. All immunized and control cattle were then challenge-exposed by allowing male Dermacentor variabilis infected with A. marginale to feed and transmit the pathogen. Nine yearling cattle (three per group) were used for this study and were immunized with cell culture-derived A. marginale, erythrocyte-derived A. marginale or received adjuvant only to serve as controls. Each vaccine dose contained approximately 2 x 10(10) A. marginale and three immunizations were administered at weeks 1, 4 and 6. At week 8, cattle were challenge-exposed by allowing 60 D. variabilis male that were infected with A. marginale as adults to feed on the cattle. Antibody responses of cattle against major surface proteins (MSP) 1a, 1b and 5, as determined by ELISAs, peaked 2 weeks after the last immunization. Cattle immunized with infected IDE8 cell-derived antigens had a preferential recognition for MSP1b while cattle immunized with erythrocyte-derived antigens had a preferential recognition for MSP1a. Protection efficacy was evaluated using the percent infected erythrocytes (PPE), the packed cell volume (PCV), and the prepatent period. A. marginale-immunized cattle showed lower PPE and higher PCV values when compared to control animals and did not display clinical anaplasmosis. The cell culture-derived A. marginale shows promise for use as antigen in development of a new killed vaccine for anaplasmosis.

Analysis of gene expression in the bovine blastocyst produced in vitro using suppression-subtractive hybridization.

Successful embryonic development is dependent on time and location-specific expression of appropriate genes. Unfortunately, information on stage-specific gene expression during early embryonic development in the bovine is lacking. In the present study, we compared gene expression between in vitro-produced Day 7-8 intact blastocysts (driver) and Day 9-10 hatched blastocysts (tester) using suppression-subtractive hybridization. Pools of 30 embryos for both driver and tester were used in the RNA extraction process. From limited amounts of starting material ( approximately 400 ng of total RNA), a reverse transcription-polymerase chain reaction (PCR) procedure was used to amplify the mRNA and generate sufficient cDNA to conduct suppression-subtractive hybridization. The subtracted cDNA products were cloned, and 126 cDNAs representing expressed mRNAs were isolated, sized, single-pass sequenced, and compared to known sequences in GenBank. Ninety-two clones provided sequence information for further analysis. Among these, 31 exhibited high homology to known genes. Three, 26S proteasomal ATPase (PSMC3), casein kinase 2 alpha subunit (CK2), and phosphoglycerate kinase (PGK) were selected and further characterized using real-time quantitative PCR to assess their differential expression in hatched blastocysts. Overall, a 1.3-, 1.6-, and 1.5-fold increase in expression level was observed in hatched blastocysts compared with intact blastocyst for PSMC3, CK2, and PGK, respectively. These results show that construction of subtracted cDNA libraries from small numbers of embryos is feasible and can provide information on gene expression patterns during preattachment embryogenesis.

Pharmacologic effects of epidural versus intramuscular administration of detomidine in cattle.

OBJECTIVES: To determine whether epidural administration of detomidine hydrochloride to cattle induced analgesia of the perineum and to compare analgesic and systemic effects of epidural versus i.m. administration of detomidine at a dose of 40 microg/kg in cattle. ANIMALS: 18 healthy adult cows. PROCEDURE: 6 cows were given detomidine by epidural administration, 6 were given detomidine i.m., and 6 (control group) were not given detomidine. Analgesia was assessed by determining responses to needle pinpricks in the perineum and flank and by applying electrical stimuli to the perineum and flank and determining the voltage that induced an avoidance response. Degree of sedation and ataxia were scored, and mean arterial pressure, heart rate, respiratory rate, and frequency of ruminal contractions were measured. RESULTS: Epidural and i.m. administration of detomidine induced comparable degrees of analgesia of the perineum and flank, accompanied by moderate sedation and ataxia, hypertension, cardiorespiratory depression, and rumen hypomotility. CONCLUSIONS AND CLINICAL RELEVANCE: Epidural and i.m. administration of detomidine at a dose of 40 microg/kg induced similar analgesic and systemic effects in cattle. Epidural administration of detomidine did not appear to be advantageous over i.m. administration.

Interaction of entomopathogenic nematodes (Steinernematidae) with selected species of ixodid ticks (Acari: Ixodidae).

Entomopathogenic nematodes, currently used for biological control of various insect pests, were tested for their ability to penetrate and kill replete females of several species of ticks including Dermacentor variabilis (Say), Rhipicephalus sanguineus (Latreille), Amblyomma maculatum Koch, and A. cajennense (F.). These species were found to be susceptible to the entomopathogenic nematodes, Steinernema feltiae (Filipjev) or S. riobravus (Cabanillas & Poinar), shown in previous studies in our laboratory to be attracted to and kill replete A. americanum. S. riobravus killed D. variabilis (96%), R. sanguineus (89%), A. maculatum (24%), and A. cajennense (88%), and S. feltiae killed D. variabilis (91%) and R. sanguineus (71%). Of the ticks that survived mean egg mass weights were significantly lower than those of the unexposed controls. When nematode-exposed ticks were examined with light microscopy, nematodes were found to have entered ticks but did not multiply or produce subsequent generations of infective juveniles. The nematodes were separated from surrounding tissues by a clear space, suggesting that they produced protective compounds. Bacteria, thought to be symbiotes released from the nematodes, multiplied initially in the hemocoel of the tick and subsequently were found throughout the degenerating tick tissues. These bacteria eventually filled the tick and appeared to be the cause of tick death. Nematode guts were filled with the bacteria, suggesting that the bacteria were a food source. When ticks were exposed to nematodes while feeding on cattle, partially engorged females were most susceptible to the nematodes. Tick mortality and reduced egg production resulted when the ticks had fed 6 and 9 d before nematode exposure but not when ticks were exposed after 3 d of feeding. Exposure of feeding female ticks demonstrated that the nematodes were able to penetrate tick orifices other than via the hypostome, which was embedded in the bovine epidermis for the duration of the feeding process.

Entomopathogenic nematodes as a potential biological control method for ticks.

Entomopathogenic nematodes have been used for biological control of certain insect pests. In these studies the nematodes were tested as a possible biological control agent for engorged female ticks. Five species of infective juveniles (IJs) were tested initially for their ability to penetrate and kill ticks, including Steinernema glaseri (SG), S. riobravus (SR), S. carpocapsae (DT), S. feltiae (SF) and Heterorhabiditis bacteriophora (HP88). Infective juveniles (IJs) of SRs and SFs appeared to be the most effective in killing ticks and invaded and killed 30 to 100% of replete females. These two nematode species were tested on several tick species including Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor variabilis and Rhipicephalus sanguineus. Although the killing rate of each tick species varied, the nematodes did not appear to be host specific and were able to kill ticks of all species tested. Egg mass weights of exposed ticks of each species were significantly lower than those of the controls. Ticks were examined with microscopy to determine whether nematodes entered and multiplied inside ticks. Partially fed female Amblyomma americanum and Dermacentor variabilis exposed to 5000 IJs in petri dishes were collected at 8, 24, 48 and 96 hrs (Trial 1) and 1, 2, 3, 4, 7 and 9 days (Trial 2) post-exposure, and fixed, processed and embedded in resin for microscopy studies. Only a few nematodes were seen in the hemocoel and tissues and they were surrounded by a clear space. Bacteria, released from the nematodes, were present in the exposed ticks and appeared to increase daily causing a generalized infection. Degeneration of tick tissues and death of the ticks appeared to result from bacterial proliferation. Nematodes did not multiply within ticks as they do in insect larvae. In these controlled laboratory studies, exposure of ticks to nematodes resulted in tick mortality and reduced egg production. Entomopathogenic nematodes appear to have potential as a biological control agent of ticks, but future studies will be required to determine whether nematode/tick interactions will occur in the field.

Preliminary studies on the effect of Anaplasma marginale antibodies ingested by Dermacentor andersoni ticks (Acari:Ixodidae) with their blood meal on infections in salivary glands.

The effect of Anaplasma marginale antibodies ingested with the tick blood meal was tested on infected male ticks that were allowed to feed on cattle immunized with the erythrocytic stage of A. marginale. The experiments were done in two trials. Trial 1 was done using splenectomized calves (two calves per treated and control groups) while ticks in trial 2 were fed on intact yearling cattle (four cattle per treated and control groups). The cattle were immunized with purified outer membrane proteins of erythrocyte-derived A. marginale using saponin (trial 1) or monophosphoryl lipid-A-trehalose dicorynomycolate adjuvant (trial 2). The corresponding control cattle received adjuvant only. All cattle were challenged using Dermacentor andersoni males infected as adults that were allowed to feed for 7 days. In trial 1, the ticks were allowed to feed a second time on susceptible calves to test whether exposure of ticks to immunized cattle affected their ability to transmit anaplasmosis. Infections in fed ticks were monitored by determining the infection rates in salivary glands with an A. marginale-specific RNA probe and light microscopy. Vaccine-derived antibodies ingested with the tick blood meal did not appear to affect the development of A. marginale in previously infected ticks. The infection rates in the salivary glands were not significantly different among ticks fed on immunized versus adjuvant control cattle. When the vaccine-exposed ticks in trial 1 were allowed to feed a second time on susceptible calves, the resulting clinical symptoms of anaplasmosis were similar to those of the controls. There was no statistically significant effect of tick exposure to the anti-erythrocytic stage antibody on the development of salivary gland infection or transmission of A. marginale by ticks.

Influence of high-starch vs high-fiber energy supplements on performance of stocker cattle grazing wheat pasture and subsequent feedlot performance.

A 3-yr study was conducted to determine effects of high-starch (HS) or high-fiber (HF) energy supplements on performance of fall-weaned steer calves (n = 192, Exp. 1 and 2; n = 84, Exp. 3) grazing winter wheat pasture (Triticum aestivum variety 2157) and subsequent feedlot performance. The steers received 1) no supplement (CL) other than free-choice access to a commercial mineral mixture or 2) were hand-fed 6 d/wk either a corn-based HS supplement, or 3) a soybean hull/wheat middling-based HF supplement. In Exp. 1 (1989-1990), a fourth treatment provided ad libitum access to the HF supplement (SFHF). Supplements contained 88 mg of monensin/kg and the combination of ionophore, minerals and salt (8%) was used to limit intake of the SFHF supplement. Target level of daily consumption of all supplements was .75% of mean BW. Stocking density was increased by 33% (i.e., from 1.24 to 1.65 steers/ha) in Exp. 1 and 3, and by 22 to 44% in Exp. 2 when supplements were fed. Subsequent to grazing wheat pasture in Exp. 2 and 3, feedlot performance and carcass quality (Exp. 2 only) of the cattle were measured. Over the 3-yr period (pooled analysis), mean daily supplement consumption was .65% BW. Daily gains were increased (P < .001) .15 kg by supplementation and were .92, 1.06, and 1.08 kg for CL, HS, and HF, respectively. Daily gains were not influenced (P > .45) by type of energy supplement. Mean supplement conversions (kilograms asfed.kilogram of increased gain-1.hectare-1) were 5.4 for HS and 5.0 for HF and did not differ (P > .95). Subsequent feedlot daily gain was decreased .09 kg (P < .05) by supplementation in Exp. 2 but not in Exp. 3 (P > .80). This supplementation program for growing cattle on wheat pasture allowed stocking density to be increased by approximately one-third and increased daily gains by .15 kg.

A comparison of anterior compartment pressures in competitive runners and cyclists.

Anterior compartment pressure was measured in 10 competitive runners and in 10 competitive cyclists who were asymptomatic for compartment syndrome. Pressures were measured at rest, after exercise at 80% VO2max, after maximal exercise, and 15 minutes after both exercise bouts. No difference in compartment pressure was found after exercise at 80% VO2max in runners and cyclists. Total creatinine phosphokinase enzyme levels measured before and after exercise at 80% VO2max showed a 10-fold increase in runners as compared to cyclists. Anterior compartment pressure measured after maximal exercise was significantly greater in runners as compared to cyclists. Compartment pressure showed no increase from resting values during cycling at 80% VO2max or maximal exercise. These findings suggest that patients with chronic anterior compartment syndrome may be able to cycle without elevation of compartment pressure and concomitant pain as an alternative exercise to maintain a continued degree of fitness and training. Compartment pressures should be measured during cycling in patients with chronic compartment syndrome to determine its efficacy as a method for maintenance of cardiorespiratory fitness.

Development of Anaplasma marginale in salivary glands of male Dermacentor andersoni.

Development of the rickettsia, Anaplasma marginale, in salivary glands of male Dermacentor andersoni exposed as nymphs or adult ticks, was studied indirectly by inoculation of susceptible calves with homogenates and directly by examination, using light microscopy and a DNA probe; some unfed ticks were incubated before tissues were collected. Salivary gland homogenates made from ticks in every treatment group caused anaplasmosis when injected into susceptible calves; prepatent periods decreased as the time that ticks had fed increased. Colonies of A marginale were seen only in salivary glands of ticks exposed as adults and not in those exposed as nymphs; the percentage of salivary gland acini infected in these ticks increased linearly with feeding time. However, the probe detected A marginale DNA in salivary glands of ticks from both groups; the amount of DNA detected increased as feeding time was extended. The amount of A marginale DNA appeared to remain constant in gut tissues, but to increase in salivary glands. Salivary glands of adult-infected male ticks that were incubated, but did not feed a second time, became infected with A marginale, and the pattern of infection of acini varied with incubation temperature. Development of A marginale in salivary glands appears to be coordinated with the tick feeding cycle; highest infection rate was observed in ticks exposed as adults.

Persistence of Anaplasma marginale (Rickettsiales: Anaplasmataceae) in male Dermacentor andersoni (Acari: Ixodidae) transferred successively from infected to susceptible calves.

The persistence of Anaplasma marginale Theiler in male Dermacentor andersoni Stiles ticks exposed to the organism as adults was studied as the ticks were successively transferred to five susceptible calves. All calves fed upon by these ticks rapidly developed clinical anaplasmosis; incubation periods of infection ranged from 19 to 26 d and did not change significantly with successive feedings. Development of A. marginale in tick midgut and salivary glands was followed daily during tick feeding (total, 35 d) with light microscopy and DNA hybridization. With microscopy, A. marginale colonies persisted in midgut cells throughout the experiment. Large colonies were observed in gut muscle cells on days 8 through 35 and were the predominant infected cell type during this part of feeding. Colonies were seen in salivary gland acini from day 2 throughout the 35-d experiment. The DNA probe confirmed the presence of Anaplasma DNA in midgut and salivary glands throughout the experiment. Quantitative estimates of infection intensity in tissues of individual ticks approximated 10(7) initial body equivalents, confirming heavy infections. A marginale in midgut tissues decreased with feeding time, whereas the estimated number of organisms in salivary glands remained constant. These data demonstrate that D. andersoni males are efficient vectors of A. marginale and may be potential reservoirs of infection for ruminants for extended periods.

Development of Anaplasma marginale in male Dermacentor andersoni transferred from parasitemic to susceptible cattle.

The development and transmission of Anaplasma marginale was studied in Dermacentor andersoni males. Laboratory-reared male D andersoni were allowed to feed for 7 days on a calf with ascending A marginale parasitemia. The ticks were then held in a humidity chamber for 7 days before being placed on 2 susceptible calves. Anaplasmosis developed in the calves after incubation periods of 24 and 26 days. Gut and salivary glands were collected from ticks on each day of the 23-day experiment and examined with light and electron microscopy. Colonies of A marginale were first observed in midgut epithelial cells on the sixth day of feeding on infected calves, with the highest density of colonies found in gut cells while ticks were between feeding periods. The first colonies contained 1 large dense organism that subsequently gave rise to many reticulated organisms. Initially, these smaller organisms were electron-lucent and then became electron-dense. On the fifth day after ticks were transferred to susceptible calves for feeding, A marginale colonies were found in muscle cells on the hemocoel side of the gut basement membrane. A final site for development of A marginale was the salivary glands. Colonies were first seen in acinar cells on the first day that ticks fed on susceptible calves, with the highest percentage of infected host cells observed on days 7 to 9 of that feeding. Organisms within these colonies were initially electron-lucent, but became electron-dense.

Development and infectivity of Anaplasma marginale in Dermacentor andersoni nymphs.

The development of Anaplasma marginale was studied in Dermacentor andersoni nymphs after they had fed on a calf with ascending Anaplasma infection. Gut tissues were collected on day 4 of tick feeding, from newly replete (fed) nymphs and on postfeeding days (PFD) 5, 10, 15, 20, and were processed for light and electron microscopy to determine density of A marginale colonies. Homogenates of gut tissues were prepared from nymphs collected on the same days and inoculated into susceptible, splenectomized calves to test for infectivity. Anaplasma colonies were detected in gut cells on PFD 5, 10, 15, and 20. Although colony density appeared to be higher on PFD 10 and 15, differences were not significant. Nymphal type-1 colonies were detected in highest numbers on PFD 5 and 10, transitional colonies were seen in highest numbers at PFD 10 and 15, and nymphal type-2 colonies were observed only on PFD 20. Gut homogenates that were collected from ticks at 4 days of feeding, when newly replete, and on PFD 20 caused anaplasmosis when injected into susceptible calves, but homogenates made from ticks collected on PFD 5, 10, and 15 were not infective. The data indicate that of the colony types of A marginale that develop in replete nymphs, nymphal type-1 and transitional colonies may contain organisms that are not infective for cattle.

Intermediate site of development of Anaplasma marginale in feeding adult Dermacentor andersoni ticks that were infected as nymphs.

The development of Anaplasma marginale in midgut epithelial cells was studied in feeding, transmitting adult Dermacentor andersoni ticks. Laboratory-reared ticks experimentally infected as nymphs were allowed to feed from 1 to 9 days on susceptible calves. Gut tissues from ticks were collected on each day they fed (total, 9 days) and were processed for light and transmission electron microscopy. Colonies of A marginale were abundant during the first 6 days of feeding, after which numbers decreased. Colonies were adherent to the basement membrane of gut cells early during feeding, with resultant flattening of the colonies. Colonies also were seen in muscle cells on the hemocoel side of the basement membrane. Morphologic features of A marginale within muscle cells varied and were similar to those observed in gut cells. In addition, however, a large reticulated form in the colonies was observed in muscle cells and appeared to give rise to small particles by budding. Development of A marginale in muscle cells appears to represent an intermediate site of development between those in gut and in salivary glands.

Needs, interests, and attitudes of university faculty for a wellness program.

During the 1986-1987 academic year, 484 full-time faculty members at Oklahoma State University responded to a health habits questionnaire. The purpose of this study was to assess the needs, interests, and attitudes of faculty for a wellness program. Behaviors were assessed in the following categories: cigarette smoking, alcohol/drugs, eating habits, exercise/fitness, stress management, and safety. Only 100 (20.6%) of the total indicated that they were currently smokers. Neither the alcohol/drugs nor the safety categories appeared to be problem areas, with no significance noted. Categories indicating a need for improvement were exercise/fitness, eating habits, and stress management. Faculty members were interested in and willing to participate in a wellness program. Preferred areas of interest in rank order were (1) exercise/fitness, (2) stress management, and (3) nutrition. Results of this study indicate that faculty in a major university are interested in wellness and will participate in a wellness program. Need and interest suggest that an exercise/fitness program should be instituted first, with stress management and nutrition components added as funds become available. A successful wellness program in a university setting has implications for happier, more productive employees, reduced absenteeism, and lower health insurance premiums.

Persistence of colonies of Anaplasma marginale in overwintering Dermacentor variabilis.

Dermacentor variabilis were infected as nymphs with Anaplasma marginale by allowing the ticks to feed on a single infected donor calf. Two weeks after molting to the adult stage, the ticks were allotted into 1 of 3 groups and were allowed to overwinter at room temperature (25 C) in the laboratory (group 1), cold storage (4.5 C) in the laboratory (group 2), or outdoors in leaf litter (group 3). Persistence of A marginale was assessed by determining density of colonies (number of colonies/0.1 mm2 of gut tissue examined) in tick gut specimens at 3, 5, 7, 9, and 12 months after molting to the adult stage. Colonies of A marginale were found in all groups at every density evaluation period. Highest colony densities were observed uniformly in specimens collected at month 7 (May); densities decreased at month 9 and were lowest at month 12. Statistical analysis indicated that ticks subjected to cold storage and to outdoor conditions had similar colony densities of A marginale; the density curve in these 2 groups indicated significant quadratic effects over time, with peak densities in May. Mean colony density in ticks kept at room temperature fit a different quadratic equation. The morphologic data indicated that A marginale overwinters in Dermacentor variabilis, and that increasing numbers of organisms are found from January to May.

In vivo test of the ability of antiserum to myotoxin a from prairie rattlesnake (Crotalus viridis viridis) venom to neutralize local myonecrosis induced by myotoxin a and homologous crude venom.

Antiserum to myotoxin a was tested for its ability to prevent local myonecrosis induced by myotoxin a and C. v. viridis venom. Antiserum was injected i.v. either 5 min before or immediately, 15 min, 30 min, 1 hr or 3 hr after i.m. injection of toxin or venom. A light microscopic method was used to measure the effects of myotoxin a, i.e. vacuolation index, and whole venom, i.e. myonecrosis index. The results show that antimyotoxin a serum neutralizes the myotoxicity of a sublethal amount of myotoxin a if injected 56 min before or immediately after toxin, but not if injected 15 min after the toxin. Its neutralizing ability for crude C. v. viridis venom was considerably better, neutralizing a dose of 0.75 microgram/g even if injection of antiserum was delayed for 30 min after venom injection. Thus, antimyotoxin a serum might be useful in treating myonecrosis resulting from prairie rattlesnake (C. v. viridis) venom poisoning.

Breath hydrogen (H2) response to carbohydrate malabsorption after exercise.

Ten subjects were studied in order to determine whether mild exercise after an overnight fast would influence the baseline breath H2 concentration or breath H2 response to the nonabsorbable disaccharide, lactulose. Breath H2 concentrations immediately after exercise were significantly lowered (p less than 0.0001) but rapidly returned to baseline values. Exercise did cause a significant change in the overall response after oral lactulose and must be considered when sequential breath H2 tests are undertaken.