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Biomedical subjects

G R Frank

Publications and source records attributed to G R Frank.

At least 19 recordsLinked to original sources
PubMed1992

Identification of Dirofilaria immitis larval antigens with immunoprophylactic potential using sera from immune dogs.

Previous research has demonstrated that dogs that received chemically abbreviated Dirofilaria immitis larval infections were significantly immune to challenge infections. Sera from those immune animals have been effective in passively transferring larval killing and stunting. In the present study, sera from immune and control animals were used to screen various Ag subsets for unique Ag. Through Western blot analysis of larval extracts and excretory-secretory products, and immunoprecipitation of metabolically labeled proteins and larval surface Ag, it was determined that as many as 12 molecules were uniquely recognized by protective immune sera. A 39-kDa molecule was present in both soluble lysates of third- and fourth-stage larvae and larval excretory-secretory products; it was recognized by each of the immune dogs and by none of the infected or uninfected control animals. The 39-kDa molecule appeared to be absent from adults and microfilariae of the parasite. In addition to the unique recognition by immune dog sera, larval stage specificity of this molecule suggests that it may be useful as a vaccine candidate.

Animals↗
PubMed1992

Dirofilaria immitis: proteases produced by third- and fourth-stage larvae.

A model of cutaneous extracellular matrix was used to determine if live Dirofilaria immitis larvae secrete proteases which are active at physiological pH and capable of degrading macromolecules found in cutaneous tissue. After 72 hr, 100 third-stage larvae (L3) degraded 24% of the total matrix, while fourth-stage larvae (L4) degraded 10%. A sharp increase in the amount of matrix degraded by L3 corresponded with the onset of the molting process. L3 and L4 degraded comparable amounts of the glycoprotein and elastin components of the matrix, but molting L3 degraded nearly twice the amount of the collagen component (62% vs 35%). Characterization of proteases present in larval-soluble extracts and excretory-secretory products using synthetic substrates and protease inhibitors demonstrated cysteine-protease and metalloprotease activity. Cysteine protease activity was found in whole worm extracts of both L3 and L4. Metalloprotease was secreted at higher levels by molting L3, but was also secreted by L4. Partial separation of the metalloprotease by size-exclusion chromatography indicated that the molecular weight of the native enzyme was in the 49-54 kDa range. The cysteine protease activity was demonstrated in fractions corresponding to 34-39 kDa. The biological function of the D. immitis larval proteases remains to be conclusively determined; however, these data suggest that they are involved in degradation of components of cutaneous tissue and in the molting process.

Amino Acid Sequence↗
PubMed1992

Molecular characterization of a Dirofilaria immitis cDNA encoding a highly immunoreactive antigen.

Dirofilaria immitis, a filarial nematode, is the causative agent of canine and feline heartworm disease. Previous research has demonstrated that immunity to D. immitis can be induced in dogs by repeated chemical abbreviation of infections while the parasite is a fourth-stage larva. Sera obtained from dogs immunized in this manner has been effective in passively transferring larval killing and stunting. These immune sera, by comparison to nonimmune sera from infected cohorts, recognize a number of unique D. immitis antigens, some of which are larval specific. In this study immune dog sera were used to screen a D. immitis larval cDNA expression library. Three overlapping cDNA clones, Di22, Di18 and Di16, were obtained that encode a portion of a large molecule, greater than 150 kDa, that is composed of multiples of a 399-bp repeat. This protein when immunoblotted with antibody against a recombinant expressed Di22 fusion protein is found in larval as well as adult extracts and excretory-secretory products, and is seen as a series of ascending subunits, each approximately 15 kDa larger than the previous one. This antigen is highly immunogenic, as evidenced by the strong reactivity of the recombinant expressed Di22 fusion protein with sera from immune dogs, microfilaremic dogs and infected amicrofilaremic dogs. While the function of this antigen is unknown it has significant sequence similarity with an allergen found in Ascaris.

Amino Acid Sequence↗
PubMed1991

A teaching phantom for sonographers.

An anthropomorphic torso section phantom is described that is intended for use during initial stages of ultrasonographer training. The phantom represents a section of the upper abdomen, with simulated ribs, liver, kidney with fat pad, gallbladder, aorta, and bowel gas. Positioned in the liver are ten simulated soft tissue masses, which produce a variety of typical echographic patterns. All simulated soft tissue components are formed of tissue-mimicking materials that match their corresponding tissue counterparts in terms of speed of sound, ultrasonic attenuation, and density. Construction details are presented and examples of images are shown.

Abdomen↗
PubMed1991

A method for in vitro mapping of ultrasonic speed and density in breast tissue.

A method has been developed for mapping density and ultrasonic speed in 1 mm thick slices of soft tissue with a resolution of about 1 mm. Tests using phantom sections have verified the accuracy and resolution of the ultrasonic speed maps. The method has been applied to breast tissues of three patients including tumors and surrounding tissue. Fixing a specimen in 5% formaldehyde did not change the degree of local variation in ultrasonic speeds, and raised mean speeds by less than 0.8%. The densities with fixing remained almost unchanged at low tissue densities (0.93 g/cm3), but rose 1.5% for higher tissue density (greater than 1.00 g/cm3).

Female↗
PubMed1991

Method of cavitation-suppressed exposure of cells and explant mouse embryos to clinical real-time and pulsed Doppler ultrasound.

An apparatus and procedure for well-controlled exposure of cells or explant mouse embryos to clinical real-time ultrasound are described. Cells or embryos to be exposed are suspended in media made sufficiently viscous through inclusion of methylcellulose that cavitation is suppressed but thermal effects remain negligible. During exposure, the scanning beam is precisely centered in a 2 mm x 20 mm slot in a 20 cm diameter agar disc containing the suspension. The high viscosity causes the cells to remain distributed uniformly throughout the exposure; this fact, along with precision beam alignment, ensures that exposure is well defined. Exposure data are acquired with a 0.6 mm diameter hydrophone.

Animals↗
PubMed1991

Metabolic labeling of Dirofilaria immitis third- and fourth-stage larvae and their excretory-secretory products.

Infective third-stage larvae of Dirofilaria immitis were collected from Aedes aegypti and cultured in vitro to the fourth stage. Larval proteins were labeled metabolically using [35S]cysteine and methionine in different media and for different lengths of time. Labeled proteins in the excretory-secretory component and the larval homogenates were evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions and by 2-dimensional gel electrophoresis. Numerous proteins ranging from 14 to greater than 200 kDa were identified from both the excretory-secretory components and the larval homogenates. Both fractions demonstrated shared and unique proteins. Using timed labeling, age- and stage-specific proteins were identified; at least 2 proteins of approximately 20.5 and 22 kDa were associated in time with the molt from the third to fourth stage. Two proteins of the same molecular weight were specifically recognized by immune dog sera, but not by sera of their infected nonimmune cohorts.

Animals↗
PubMed1991

Chemoprophylactic effects of milbemycin oxime against larvae of Dirofilaria immitis during prepatent development.

Three studies were conducted to determine the efficacy of milbemycin oxime in the prevention of Dirofilaria immitis infection in dogs. Dogs were given single or multiple experimental inoculations with infective third-stage D immitis larvae and were treated with milbemycin oxime at a target dosage of 0.5 mg/kg of body weight either once or at monthly intervals at various times after inoculation. The compound was effective in preventing infection when 1 dose was administered 30 or 45 days after inoculation. Significant, but incomplete, protection was achieved when single treatments were administered 60 or 90 days after inoculation. Multiple monthly treatments beginning 60 days after inoculation appeared to provide additive effects that resulted in restoration of complete efficacy.

Animals↗
PubMed1988

Use of a disease reporting system in a large beef feedlot.

A large commercial beef feedlot in northeastern Colorado was selected by stratified random process for inclusion in the National Animal Health Monitoring System pilot data collection project. Various records in the feedlot were used to collect data related to animal health conditions and to their costs. A total of 57,727 cattle were processed during the 12-month period of the study. Rates were used to adjust for the number of cattle in the feedlot during that period. The disease incidence, culling rate, and death rate were presented by each month in the study. The monthly mean number of cattle was the denominator for these rates. During the 12 months, 72 diseases or abnormal conditions were recorded. The total cost of the 10 most prevalent diseases (itemized by dead, culled, treatment, and income from selling dead animals) accounted for approximately 77% of the total cost of disease in the feedlot. The total cost of lower respiratory tract diseases contributed approximately 46% of the total disease cost, and 60% of the cost of the 10 most prevalent diseases. In order to consider the reporting methods reliable, a separate study was undertaken to validate a reported disease or condition in the feedlot.

Animals↗
PubMed1988

Validation of disease diagnoses reported to the National Animal Health Monitoring System from a large Colorado beef feedlot.

Clinical observation and collection of biological specimens from a large beef feedlot (approximately 30,0000 animals) were used to evaluate 6 approaches for validation of a disease reporting system. Data collected during a 12-month period were used to evaluate each approach. A subsample of disease cases reported to the National Animal Health Monitoring System (NAHMS) was compared with the clinical observations of the investigators. Although the agreement between clinical diagnosis by the NAHMS veterinarian and by feedlot health crews was high, the sensitivity and specificity of specific diagnoses varied from 100 to 18% and from 99 to 76%, respectively, which suggests that regular clinical observations by a veterinarian are needed to validate disease diagnoses reported to NAHMS by producers. Subsampling of a group of cattle by means of paired serologic determination of antibodies to infectious bovine rhinotracheitis virus, bovine viral diarrhea virus, bovine respiratory syncytial virus, and parainfluenza-3 virus revealed a high serologic conversion rate to infectious bovine rhinotracheitis, and high levels of preexisting antibody to bovine respiratory syncytial and parainfluenza-3 viruses. It was concluded that the current method of data collection for Colorado feedlots provides an acceptable level of sensitivity and specificity for the program. However, disease events that are not of economic importance to the feedlot operator will be underestimated. If an objective of NAHMS is to develop a base line of animal health conditions, diagnosis of diseases by current methods will be satisfactory. Occasional validation through clinical observations by a veterinarian will suffice to monitor quality of collected data.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Anthropomorphic phantoms for assessing systems used in ultrasound imaging of the compressed breast.

Two anthropomorphic phantoms, simulating the breast as it is compressed against the chest wall during ultrasonic imaging, are described in detail regarding structural configurations and distributions of ultrasonic properties. The external shape of each phantom is that of a rectangular parallelepiped; this simple shape is consistent with the breast in the compressed configuration and also facilitates the inclusion of a considerable variety of simulated lesions including comparisons of imaging as a function of depth. One of the phantoms was completed about 4 1/2 years prior to this writing, and images made with scanners which were state-of-the-art in late 1983 and 1984 are compared with images made with two current state-of-the-art imagers. Improvements in imager quality over that period are apparent. The more recently produced phantom contains a simulated tumor with a complex structure as well as realistic simulated calcifications of various sizes. The tumor has a necrotic core and an irregularly shaped boundary. This boundary possesses a roughness intended to give rise to diffuse reflection.

Agar↗
PubMed1988

Riboflavin requirement of lactating swine.

Twenty-five crossbred gilts and 25 crossbred sows were used in an experiment to estimate the riboflavin requirement of lactating swine. During gestation the females were fed a 12% crude protein, corn-soybean meal diet that was marginal in riboflavin content, i.e., 2.3 mg/kg. After farrowing, litter size was equalized across lactation diets within each parity category. The basal, 14% crude-protein corn-soybean meal lactation diet was supplemented to provide five levels of dietary riboflavin: 1.25, 2.25, 3.25, 4.25 and 5.25 mg/kg. Five gilts and five sows were fed each dietary treatment. Each dam was provided her assigned diet ad libitum during the 24-d lactation; piglets were not provided supplemental feed. The erythrocyte glutathione reductase activity coefficient (EGRAC), an indicator of riboflavin status, was measured on blood samples obtained from the dams and their piglets on d 1 and d 24 postpartum. On d 1, the mean EGRAC of gilts was slightly higher than that of sows, while piglet EGRAC was similar regardless of maternal age. On d 24 gilts and their piglets had higher average EGRAC (P less than .01) than did sows and their piglets. Thus, there was a treatment x dam age interaction (P less than .05). Lactation performance criteria gave further evidence of similar treatment x age group interactions. Gilts fed the diet containing 1.25 ppm riboflavin had higher piglet mortality, consumed less feed and lost more weight (P less than .05) for each criterion than did sows fed the same diet. Despite these observations, the broken-line estimates of the riboflavin requirement, based on EGRAC, for gilts and sows were 16.3 and 16.2 mg/d, respectively. The EGRAC values for piglets closely paralleled those of their dams regardless of treatment, suggesting that there is no mechanism to protect the nursing piglets from a maternal dietary deficiency of riboflavin.

Animals↗
PubMed1988

Prevalence and specificity of antibodies to bovine respiratory syncytial virus in sera from feedlot and range cattle.

The specificity of serum antibodies for the polypeptides of bovine respiratory syncytial virus (BRSV) was examined, using sera obtained from feedlot and range cattle. Test results in sera from feedlot cattle indicated a 60% rate of seroconversion and 95% seropositivity to BRSV, associated with lack of clinical signs indicative of respiratory tract disease. Exposure to other common respiratory tract viruses also was high (greater than or equal to 92% to bovine herpesvirus type 1, bovine viral diarrhea virus, and para-influenza virus type 3). Test results in sera from range cattle indicated BRSV seropositive rates of 28% in calves, 49% in yearling cattle, and 70% in mature cows; clinical signs of respiratory tract disease were not observed in these cattle. Antibodies to BRSV in sera from cattle in both environments reacted predominantly with polypeptides of molecular weight 80,000 through 85,000, 40,000, and 28,000. Reactivity to a glycoprotein of molecular weight between 43,000 and 44,000 and to several glycopolypeptides of smaller molecular weight increased in serum specimens obtained from feedlot cattle between time of entry into the feedlot and slaughter.

Animals↗
PubMed1986

Interlaboratory comparison of ultrasonic attenuation and speed measurements.

A set of test samples, all containing ultrasonically equivalent tissue-mimicking material, was produced and measurements of ultrasonic speed and ultrasonic attenuation coefficients were made at seven laboratories using various techniques. The ultrasonic speed values agree well with one another, having a spread of about 0.3 per cent; thus, speed values for tissue parenchyma appearing in the literature are likely to be accurate. Values of ultrasonic attenuation coefficients agree fairly well with one another, with differences between individual values and the group mean of generally less than 20 per cent of the group mean.

Humans↗
PubMed1984

Riboflavin requirement of gestating swine.

Forty crossbred gilts (9 to 10 mo of age) were used to determine the riboflavin requirement for gestating swine. Upon mating, gilts were assigned to one of five levels of dietary riboflavin (.77, 1.77, 2.77, 3.77 or 4.77 ppm) and individually fed 2.0 kg daily of the assigned diet throughout gestation. Gilts were bled on d 7, 24, 30, 35, 40, 56, 70, 84, 90 and 97 postcoitum. On d 1 postpartum, all sows and their live piglets were bled. Hemolysates of isolated, washed erythrocytes were prepared from blood samples and assayed to establish the erythrocyte glutathione reductase activity coefficient (EGRAC) as an indicator of the riboflavin status of each animal. The higher the EGRAC, the greater the severity of the riboflavin deficiency. During gestation, the EGRAC of gravid gilts increased with time in a manner dependent upon the level of dietary riboflavin. Postpartal EGRAC were elevated in dams fed the three lowest levels of dietary riboflavin during gestation. Of the six gravid gilts fed .77 ppm riboflavin, four gilts gave birth, approximately 7 d prematurely, to stillborn litters while two gilts failed to farrow by 121 d postcoitum. Litter weights at birth and gestation weight gains of these gilts were less than those of gilts fed the higher levels of riboflavin. Postnatal mortality of piglets was greater for those litters from sows fed 1.77 ppm riboflavin than for those from sows fed higher levels of riboflavin. The riboflavin status of newborn piglets was similar to that of their dams as determined by EGRAC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗