Search

Sheep infested with screwworms, Cochliomyia hominivorax (Coquerel), produced specific serum antibodies detectable by ELISA. Significant antibody levels were found beginning at 1 wk after infestation and persisting for 2 mo, with peak levels at 3 wk after infestation. Mean response values and corresponding larval survivorship were similar over a range of 25 to 200 larvae per individual sheep. Anomalous seropositive responses in some noninfested sheep suggested the possibility of cross-reactivity between antigens of screwworm and those of related myiasigenic blowflies.

The cerebellum of the meander tail mutant mouse is characterized by normal cytoarchitecture in the posterior lobe and agranular, abnormal cytoarchitecture in the anterior lobe. The Purkinje cells form a monolayer in the posterior lobe but are dispersed throughout the cortex of the anterior lobe. Examination of these cells with the zebrin antibodies demonstrates that in spite of the morphologic and laminar disorganization of these cells in the anterior lobe, they are organized into the appropriate number of correctly positioned immunopositive zebrin clusters.

Cattle infested with the common cattle grub, Hypoderma lineatum (Villers) develop specific humoral antibodies and a cellular immune reaction, defined by delayed-type hypersensitivity, to purified H. lineatum proteins. This investigation was designed to study the antigen-specific bovine lymphocyte response to hypodermin A (HyA), a serine protease of larval first-instar H. lineatum. Calves were vaccinated with either native or denatured HyA, and challenge-infested with H. lineatum. The kinetic development of a cellular immune response to HyA was monitored during vaccination and infestation. The HyA-specific responses were highly variable and weak during vaccination and infestation. Although HyA-specific lymphocyte blastogenic responses were observed, no correlation was noted between the magnitude of antigen-specific, peripheral lymphocyte proliferation and larval mortality. In striking contrast to responses observed during infestation, intense HyA-specific lymphocyte responses were observed with 3 calves 6 months after recovery from infestation. In addition, those responses were further heightened by a 250 micrograms booster injection of pure HyA.

1. The individual and combined effects of sufentanil and sodium pentothal on canine coronary artery vasomotor responses to 5-HT were studied in an isolated vascular ring preparation. 2. Clinical concentrations of sufentanil have little effect on basal coronary tension or constriction induced by either 5-HT or sodium pentothal individually, until very high doses greater than 0.26 microM are reached. 3. Sodium pentothal causes coronary constriction at clinical concentrations and this effect is additive and possibly potentiated when combined with 5-HT. 4. Sufentanil inhibits coronary constriction induced by the combination of sodium pentothal and 5-HT.

Cattle are known to acquire immunological resistance to hypodermyiasis by repeated exposure to both species of cattle grubs, Hypoderma lineatum (Villers) and Hypoderma bovis (L.). Vaccination of cattle with purified proteins of H. lineatum, particularly hypodermin A, is known to protect cattle against hypodermyiasis by this species. The development of a protective recombinant vaccine against both species using hypodermin A isolated from H. lineatum would require that immunological epitopes be shared by complementary proteins in H. bovis. The purpose of this study was to investigate the soluble proteins of H. bovis first-instars for shared epitopes with H. lineatum. Soluble H. lineatum and H. bovis first-instar larval proteins were resolved by nondenaturing polyacrylamide electrophoresis, blotted onto nitrocellulose paper, and probed with selected polyclonal cow, polyclonal rabbit, and mouse monoclonal antisera. Considerable cross-reactivity was demonstrated by antibodies in the serum of an H. lineatum-infested cow as 6 of 10 resolved H. bovis proteins were bound by the antibodies. The most common shared epitope(s) was associated with hypodermin C, a collagenolytic protease. Hypodermin A shared epitope(s) were noted on 1 prominent H. bovis band (HB1-2). Hypodermin B, a prominent protein in H. lineatum, did not appear to share epitopes with H. bovis proteins. Shared epitopes between H. bovis proteins and hypodermins A and C of H. lineatum would suggest that cross-protection of cattle against H. bovis can be expected by vaccination with recombinant proteins of H. lineatum.

The use of a transthoracic bioimpedance monitor to determine cardiac output was evaluated in critically ill children. The children ranged in age from 10 months to 8 yr and their height and weight ranged from the third to the 97th percentile. Each child had a thermodilution catheter in place to monitor cardiac output. The bioimpedance monitor used in this study, the NCCOM-3, required the input of a constant (L), which was obtained for each individual patient by adjusting the L setting until cardiac output measured by bioimpedance (COBI) was within 10% of cardiac output measured by thermodilution (COTD). This method of determining L was superior to using either measured thoracic length or the manufacturer's guidelines to obtain L and resulted in an excellent correlation between COTD and COBI (r = .94; p less than .05; n = 59). In children less than 125 cm in height, measured thoracic length alone was inadequate to use for L but provided a good approximation of L when multiplied by 1.25. This study suggests that the use of transthoracic bioimpedance to determine cardiac output compares favorably with thermodilution techniques and it is noninvasive.

The synthetic glucocorticoid dexamethasone was used to suppress bovine T-lymphocyte function. Dexamethasone-treated animals were challenged with Psoroptes ovis (Hering) to determine if the immunosuppressive treatment would normalize susceptibility to infestation. Dexamethasone suppressed T-lymphocyte function and anti-P. ovis antibody production, and delayed the onset of scab lesions. All animals were not equally susceptible to infestation as a result of dexamethasone treatment. These data further support the importance of anti-P. ovis antibody in colonization of cattle by P. ovis and the pathology associated with scab mite infestation.

The Walton-Brodie strain gauge arch is an instrument that quantitatively measures CF. Like many methods, the strain gauge arch is affected by loading conditions and heart rate. Nevertheless, this methodology, when properly used, has proved very useful in describing the direct action of anaesthetic drugs. Knowledge from strain gauge arch use has stimulated research to explain the negative inotropic effect of anaesthetics and helped clinicians understand the cardiovascular effects of drugs that they may wish to use.

Nine Hereford calves were infested with Psoroptes ovis and were allowed to develop clinical mange during a 9-week period. Blood, serum, and urine samples were obtained before and after calves were infested and were compared with those from 3 noninfested control calves. All calves were euthanatized and necropsied 9 weeks after they were infested. Gross and microscopic anatomic changes occurred only in the skin. Calves developed typical exudative dermatitis, the extent of which was dependent on population density of mites. Severely infested calves (50% to 70% of skin with dermatitis) developed a mild anemia and lymphopenia with marked neutropenia and variable eosinophilia. There were also increases in fibrinogen, gamma-globulin, and in vitro lymphocyte response to mitogen stimulation and decreases in anion gap cortisol, albumin, albumin/globulin ratio, and fractional Na clearance values. The severity of many of the changes could be correlated with the extent of dermatitis.

A grazing-incidence grating-tuned oscillator followed by two amplifier stages has been used to generate 0.2-cm(-1) bandwidth scannable infrared radiation between 1.09 and 1.12 microm. When the radiation was pumped with 400-mJ 10-nsec pulses from a Nd:YAG laser, the output-pulse energy was approximately 20 mJ at the peak of the tuning curve.

The vasodilatory effect of the synthetic glucocorticoid methylprednisolone was studied in the vascular bed of the isolated hind limb of the dog. The isolated hind limb was perfused with the animal's blood by means of a roller pump at a flow to maintain a constant control pressure. The effects on hind limb pressure of alpha- and beta-agonists, sodium nitroprusside, and methylprednisolone sodium succinate were observed in unblocked (Group I) as well as in alpha- and beta-adrenoceptor blocked (Group II) animals. The agonists epinephrine (2 micrograms) and isoproterenol (0.5 micrograms) caused significant increases (+45%) and decreases (-43%) in hind limb pressure, respectively, and both sodium nitroprusside (100-200 micrograms) and methylprednisolone (500 mg) caused significant decreases in hind limb pressure of unblocked animals. In animals with adrenoceptors blocked by phenoxybenzamine and propranolol (Group II) the agonists produced no significant effects, but the methylprednisolone and sodium nitroprusside caused significant decreases in pressure, 45% and 28%, respectively. Following vasodilatation by methylprednisolone, sodium nitroprusside caused a slight, but not significant decrease in hind limb pressure. These data show that methylprednisolone will produce significant vasodilatation even in the presence of alpha- and beta-adrenoceptor blockade, indicating that adrenoceptors alone cannot account for the vasodilatory actions of the steroid in the isolated hind limb.

Protein species found in soluble crude extracts of Hypoderma lineatum (common cattle grub) 1st-instar larvae (HL1) were separated by non-denaturing and denaturing polyacrylamide gel electrophoresis (PAGE) and analyzed for antigenicity by Western blotting using serum from H. lineatum-infested and vaccinated cattle. All HL1 proteins resolved by non-denaturing PAGE were found to be antigenic in the infested bovine host. Treatment of the proteins with sodium dodecyl sulfate and 2-mercaptoethanol destroyed the ability of hypodermin B and the Peak 2 proteins from DEAE-ion exchange HPLC to be bound by antibody. The principal proteins, hypodermin A and hypodermin C (collagenase), appear to be the most immunogenic of the larval proteins. Although having similar amino acid composition, hypodermin A did not appear to share an antigenic epitope with the most prevalent protein, hypodermin C. These results may allow for the selection of proteins to be used in vaccine trials and studies of protective immunological mechanisms associated with acquired resistance to H. lineatum infestation in the bovine host.

The electrophysiologic effects of high concentrations of the opioid agonists, fentanyl and sufentanil, on isolated canine cardiac Purkinje fibers were studied. Changes in action potential parameters were examined at the following concentrations: fentanyl 94.6 nM, 0.19 microM, and 0.95 microM; sufentanil 8.6 nM, 86.4 nM, 0.17 microM, and 0.26 microM. Naloxone 5.5 microM was administered after maximal changes were induced by fentanyl in order to explore the possibility of an opioid receptor interaction. Action potential parameters measured were Vmax of phase 0, amplitude, overshoot, maximum diastolic potential, action potential duration at 50%, and 90% repolarization and membrane responsiveness. Fentanyl 0.19 microM and sufentanil-0.17 microM caused a significant lengthening of action potential duration at 50 and 90% repolarization, 6.4% and 7.3%, and 10.2% and 12.4%, respectively, P less than 0.05. Other action potential parameters were not significantly affected by the opioids. Naloxone 5.5 microM alone did not alter action potential characteristics and failed to reverse action potential prolongation produced by fentanyl. The authors suggest that fentanyl and sufentanil prolong action potential duration in canine cardiac Purkinje fibers via direct membrane actions.

The purpose of this study was to examine the effect of a methylthio substituent in the metabolically most active position of propranolol, i.e. the 4'-position, on the pharmacokinetics and metabolism of this drug in the dog. The kinetics of 4'-methylthiopropranolol (MTP) were compared to those of propranolol following simultaneous iv doses of labeled drug and oral doses of unlabeled drug. MTP had a significantly larger volume of distribution and a longer half-life, and demonstrated a greater accumulation by red blood cells and cardiac conductile tissue than propranolol, effects which presumably are due to a higher lipophilicity of MTP. The greatest effect was on the oral clearance, which was substantially lower for MTP (1.6 vs. 5.5 liters/min) with an associated higher bioavailability (23.1 vs. 10.9%). Studies of MTP metabolism using radiolabeled drug showed that MTP, like propranolol, was eliminated entirely by metabolism. About 70% of the urinary radioactivity was extractable into ethyl acetate at pH 9.8 and pH 2.0. The extractable metabolites were separated by HPLC and identified by GC/MS, direct probe MS, and comparison with authentic compounds. Eleven metabolites were identified as sulfoxides and, in particular, sulfones of MTP and its N-dealkylated and subsequently deaminated glycollic and lactic acid metabolites. The nonextractable urinary radioactivity (30%) was isolated by DEAE-Sephadex chromatography and identified by HPLC/MS as four glucuronic acid conjugates. In contrast to propranolol, there was no evidence of aromatic carbon oxidation for MTP. These observations suggest that the markedly decreased oral clearance of MTP compared to propranolol is due to qualitatively altered metabolism from a highly efficient aromatic carbon oxidation for propranolol to a less efficient sulfur oxidation for MTP.

The interrelationship between drug-induced changes in heart rate and drug-induced alterations in ventricular automaticity was studied in dogs with intact conduction systems and dogs with surgically-induced complete heart block. The effects of epinephrine (0.5 microgram-kg-1-min-1) and propranolol (1.0 mg-kg-1) on ventricular automaticity were shown to be partially concealed by heart rate changes produced by these agents. Partial concealment of ventricular automaticity changes was shown to result from an alteration in the degree of overdrive suppression secondary to rate changes. Changes in the degree of overdrive suppression have a masking effect on drug-induced alterations in ventricular automaticity and only when the degree of suppression was held constant could the full extent of drug effects on ventricular automaticity be determined. Following vagal stimulation or rapid pacing, the rate of recovery from overdrive suppression as measured by the number of ventricular beats in 30 s was shown to be a dependable index of ventricular automaticity. It was concluded that determinations of drug effects on ventricular automaticity should take into account changes in heart rate produced by the drug. A method for determining ventricular automaticity is described which matches overdrive suppression during the control period to that during drug action in order to cancel out the influence of changes in heart rate on ventricular automaticity.

Antibodies to Hypoderma lineatum were transferred to calves via colostrum. The antibodies transferred in the colostrum demonstrated specificity to all the H. lineatum first-instar proteins which were resolved by non-denaturing polyacrylamide gel electrophoresis and were capable of mediating a Type I hypersensitivity reaction. The kinetic decline of colostrum-acquired antibodies, the effect upon development of an autologous humoral response to H. lineatum and the host or parasite protective role of these antibodies are discussed.

Bovine scabies in a clinical problem during the cool autumn and cold winter months. In south Texas it is necessary to stanchion animals in order to elicit patent infestation during summer months. Environmental factors and grooming have been purported to account for summer resistance to infestation. However, stanchioned animals exhibit varied levels of susceptibility to infestation, suggesting that the noted variability may be influenced by the host immune response. In this study, animals were infested with Psoroptes ovis while in stanchions. The development of anti-P. ovis antibody activity was measured by the enzyme-linked immunosorbent assay and cellular immune function was monitored with mitogens and P. ovis antigens. A correlation was noted between the development of anti-P. ovis antibody activity and the increase in mite numbers and dermatitis. Coincident with the developing infestation was a suppression of T-cell function that appeared to be stress-related as a result of stanchioning. A working hypothesis is presented that attempts to correlate the developing humoral response and the depressed T-cell response with both an increasing dermatitis and mite population.

An enzyme-linked immunosorbent assay method was used to classify bovine serum as positive, negative, or doubtful for antibodies to Brucella abortus. Spectrophotometric data from assays of 64 serologically positive and 32 serologically negative bovine sera were analyzed statistically to define the range of spectrophotometric absorbance values which classify sera. Statistical analysis indicated that absorbance values less than 0.08 should be considered negative and values greater than 0.14 should be considered positive, with intermediate values declared doubtful, and that the probability of erroneously classifying a positive serum as negative or a negative serum as positive is less than 0.005.

The determination of urinary N-monomethylacetamide (MMAC) in the end-of-shift urine sample was used to monitor exposure to dimethylacetamide (DMAC). Five workers were observed followed for 4 consecutive weeks. Airborne DMAC appeared to account for the greatest amount of urinary MMAC detected and, at the exposure concentrations encountered (0.5 to 2 ppm), a relationship of 10 ppm urinary MMAC for each 1 ppm DMAC inhaled was observed. Interindividual variation was small and no evidence of build-up in MMAC urinary levels was seen in these subjects. Mean airborne DMAC concentrations were somewhat higher by the end of the week, but the magnitude was such that the differences were not statistically significant. It is concluded that changes in DMAC exposures can be quantitatively reflected by urinary MMAC.

WI 38 human fetal lung fibroblasts were incubated with tracer amounts of 14C-labeled formaldehyde and acetaldehyde which are highly reactive components of cigarette smoke. A pulse of 10 min with formaldehyde followed by a 60-min and 24-hr chase showed migration of 14C label into the nucleus. Fractionation of the nucleus revealed that the RNA fraction had the highest absolute and specific activity while the DNA and protein fractions contained considerably lower activities. All of the counts from formaldehyde were found in the adenine and guanine components of RNA. The DNA counts were distributed among adenine, guanine, and thymine. Incubation with 14C acetaldehyde showed a majority of the counts localized in the membrane plus nuclear lipid fraction. A small proportion of counts was found in the protein portion of the cells.

Protein species found in crude extracts of Hypoderma lineatum (Villers) 1st-instar gullet-stage larval homogenates were fractionated by chromatography and further identified by conventional polyacrylamide gel electrophoresis (PAGE) and SDS/PAGE techniques. Seven major fractions were resolved by ion exchange chromatography. Conventional PAGE of the crude antigen preparation revealed a minimum of 14 protein species, while SDS/PAGE revealed 3 major protein species. The ability to elicit cutaneous reactivity by isolated proteins was determined by the intradermal skin test. An immediate-type hypersensitivity reaction was elicited in the skin of vaccinated and previously infested animals by the components of the 4 protein fractions tested. Only one protein fraction, fraction 4, elicited an apparent delayed reaction at 48 h in vaccinated and previously infested animals. A non-specific background reaction was elicited in control animals by the fractionated proteins and was most notable between 1- and 4-h post-injection.

An enzyme-linked immunosorbent assay (ELISA) method was evaluated for the detection of antibodies to Brucella abortus in cows milk. Milk samples from seropositive or -negative cows were sed to determine the distribution of absorbance values to classify milk as ELISA positive or ELISA negative. Brucella abortus was isolated from milk samples from 10 (45%) of the 22 cows whose milk and serum were ELISA positive. The ELISA was evaluated and determined to be an appropriate method for detecting antibodies to B abortus in bovine milk.

We examined human immunodeficiency virus (HIV) production in cultured mononuclear cells from 36 seropositive homosexual males. Production was detected by using an HIV p24 antigen ELISA assay in blood mononuclear cells in 54% of asymptomatic, 71% of acquired immunodeficiency syndrome (AIDS)-related complex, and 100% of AIDS patients. When the peripheral blood mononuclear cells were separated into monocytes and CD4+ T cells, we found that the CD4+ T-cell fraction was preferentially infected in the three clinical stages. The ability to isolate HIV from blood monocyte-derived macrophages was similar in the three stages (24-33%) and required coculture with phytohemagglutinin-stimulated lymphoblasts. Bone marrow and blood mononuclear cells cultured simultaneously yielded virus from both sources in 13 individuals. Again the prime source of virus was the nonadherent bone marrow mononuclear cells, which contained CD4+ T cells, and not the adherent monocyte-enriched fraction. We conclude that blood mononuclear cells yield productive virus more readily as disease progresses and that infection is detected in association with CD4+ T-cell-enriched fractions. In our large sample of patients, monocyte infection was detected in only a small fraction, suggesting that this cell type is neither a primary nor an exclusive reservoir of HIV infection.