Evidence that B-lymphocytes carry the nuclear pocket abnormality associated with bovine leukemia virus infection.

Peripheral blood lymphocytes from 3 cows with persistent lymphocytosis were separated on nylon wool columns into nylon wool-adherent and nonadherent populations. The percentage of cells coated with surface immunoglobulin (B-cells) and the frequency of lymphocytic nuclear pockets in each sub-population were then determined. In each case the adherent population consisted predominantly of B-cells with an increased nuclear pocket frequency, whereas the nonadherent cells were 98.99% negative for surface immunoglobulin (non-B-cells) and contained essentially no nuclear pockets. These findings provided additional evidence that the B-subpopulation of cells was highly involved in bovine leukemia oncogenesis.

Chloramphenicol pharmacokinetics in infants less than three months of age in the Philippines and The Gambia.

BACKGROUND: The broad antimicrobial spectrum and affordable price of chloramphenicol make it an attractive first line treatment option for children with severe illnesses in developing countries. Little is known, however, about its pharmacokinetics in young infants in these settings. METHODS: We studied infants younger than 3 months of age hospitalized in Manila, Philippines and The Gambia with possible severe bacterial infections likely to benefit from treatment with chloramphenicol. Infants in the first week of life received intramuscular doses of 25 mg/kg chloramphenicol once daily, twice daily in the second through fourth week of life and three times daily from 5 to 12 weeks of age. Blood samples were taken at 0.5, 1, 2 and 3 h after the first dose, 1 h before the second dose and before the repetition doses on subsequent days. In the Philippines a second group of infants was treated with oral chloramphenicol according to the same dosage schedule. RESULTS: Thirty-eight infants received intramuscular chloramphenicol, and 20 received oral drug. Intramuscular administration resulted in therapeutic concentrations (10 to 25 microg/ml) in 73 to 86% of children in each of the three age groups in the first 6 h and in 50 to 80% on Days 2 and 3. Between 33 and 38% of children had potentially toxic values on Days 2 and 3. In contrast, after oral administration, only about one-half of the children reached therapeutic values in serum at any time up to Day 3 after start of treatment. CONCLUSIONS: Intramuscular chloramphenicol can be used as a second line drug for the treatment of severe infections in infants younger than 90 days of age, where third generation cephalosporins are not available. It quickly achieves therapeutic values in a high proportion of children. However, severe infections should not be treated with oral chloramphenicol in this age group, because therapeutic serum concentrations were inconsistently achieved.

Detection of bovine leukemia virus in cattle by the polymerase chain reaction.

Bovine leukemia virus (BLV) is widely distributed in U.S. cattle herds. It infects B lymphocytes and causes neoplastic disease in 5-10% of infected animals. Direct economic losses are incurred as a result of death, reduced milk production and condemnation at slaughter. Thus the identification of cattle infected with BLV is of significant concern to the U.S. cattle industry. For this reason, polymerase chain reaction (PCR) amplification was used to examine seropositive and seronegative cattle for the presence of BLV DNA in peripheral blood mononuclear cells. Using an amplification protocol able to detect 1 viral genome in 100,000 cells, BLV was not detected in 7 seronegative cattle in an infected herd. BLV sequences were detected in 13 of 18 seropositive animals with various levels of infection as determined by in vitro lymphocyte culture and electron microscopy. An active infection was demonstrated in one animal, based on the presence of viral RNA. These findings indicate that PCR is a sensitive method for the detection of BLV in cattle and provides new information regarding the dynamics of the infection.

X trisomy in an Airedale bitch with ovarian dysplasia and primary anestrus.

A 79,XXX chromosome complement was detected in a four-year-old Airedale Terrier bitch examined for primary anestrus. Serum concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were markedly elevated. Ovaries contained solid epithelial cords and large masses of interstitial cells but lacked follicles and corpora lutea. Somatic abnormalities were not observed. X trisomy is reviewed in six species in which it has been described.

A chromosomal reciprocal translocation (1q+; 14q-) in a boar siring reduced litter sizes.

In our initial cytogenetic surveillance of boars one of 15 was found to be hypoprolific. It averaged 7.1 piglets per litter in over 51 monospermic matings with sows which, with other boars averaged 10.8 piglets per litter. Cytogenetic evaluations revealed only the hypoprolific boar to have an abnormal karyotype, namely {38XY, t(1;14) (q2.12, q2.2)}. This represents a new type of 1;14 reciprocal translocation, and also the first report of a reciprocal translocation for swine in the United States.

X-chromosomal monosomy (77,X0) in a Doberman Pinscher with gonadal dysgenesis.

A 6-month-old stunted female Doberman Pinscher was found to have a 77,X0 chromosomal complement. The ovaries were small, consisting primarily of interstitial-type cells and solid epithelial cords. The dam, sire, and a male littermate had normal karyotypes.

Occurrence and fate of corpora amylacea in the bovine udder.

The presence and location of corpora amylacea were studied quantitatively by biopsy technique in separate glands of a normal cow during a lactation cycle. Corpora amylacea were present in alveoli throughout lactation without any evidence of an abnormal bacterial flora or an inflammatory reaction. The corpora amylacea were most numerous during the decline in lactation, approximately 95% being in the alveoli. During the nonlactating (dry) period, there was approximately a 50% decrease in the number of corpora amylacea, with about 90% of those remaining being in the interstitial tissue. They appeared to enter the interstitial tissue passively coincident with atrophy of alveoli.

Long-term stability of blood lymphocyte nuclear pocket prevalence in clinically normal adult dairy bulls.

A study on blood lymphocyte nuclear pocket (LNP) prevalence stability was made over a 2-year period on ten clinically normal adult Holstein-Friesian bulls. The design of the experiment included 3 categories of animals as follows: (a) 3 bovine leukosis virus (BLV)-seronegative bulls (N); (b) 4 BLV-seropositive bulls and initial low (less than 1.0%) blood LNP prevalence; and (c) 3 BLV-seropositive bulls with initial high (greater than or equal to 2.0%) blood LNP prevalence. Prevalences of LNP for individual animals in all three groups were stable as to category of initial designation during the 2-year period. All animals initially designated as seronegative or seropositive remained so throughout the experiment. Essentially, correspondence between LNP concentration and BLV serotiter was observed only in the seronegative group in which prevalence was low on all samples. Because increased LNP prevalence has been shown to be related to in vitro C-type BLV production and beacuse LNP prevalence appears to be stable, this measurement may be of discriminatory value in studies to develop criteria for the disposition of enzootic bovine leukosis seropositive cattle.

Prevalence of atretic corpora lutea in ovaries of bovine fetuses.

Both ovaries from 88 bovine fetuses in the fifth month or later of gestation were studied histologically to determine the prevalence, origin, and time of appearance of atretic corpora lutea (ACL). Ovaries from 36 (41%) fetuses had ACL; fetuses < 6 months of gestation did not have ACL. Six fetuses had more than 25 ACL, but there was no apparent relationship between fetal age and number of ACL. Formation of ACL involved disintegration of the stratum granulosum of secondary follicles, concomitant with proliferation and invasion by vascularized elements of the theca. Fully developed ACL consisted of a large primary oocyte surrounded by a prominent zona pellucida and encased in a well-vascularized, largely thecal, fibrocellular wall. They measured approximately 0.5 to 1.0 mm in diameter. Empty, collapsed zona pellucidas were seen in many of the degenerating ACL.

Failure to demonstrate transmission of enzootic bovine leukemia virus infection from cows to sheep by use of common injection needles.

Four bovine leukemia virus (BLV)-seropositive and 2 BLV-seronegative cows were used as donors in a study to provide evidence whether IM injection with common needles is a means of spreading bovine leukemia. Sheep were used as recipients. Of the 4 BLV-seropositive cows, 2 had high virus expression (VE; 43% and 28% of their lymphocyte thin sections had associated BLV-particles), whereas the other 2 cows did not have observed VE. After each of the 4 cows was given an injection of a 5-antigen Leptospira bacterin, a BLV-seronegative sheep was immediately given an injection of the same bacterin with the same needle. None of these sheep seroconverted, nor did either of 2 sheep given only the bacterin (with a previously unused needle). Sheep inoculated IM with 0.2 ml of whole blood from both of the cows with high VE and from 1 of the 2 BLV-seropositive cows that did not have observed VE did seroconvert. In contrast, the sheep inoculated with 0.2 ml of blood from the remaining BLV-seropositive (0% VE) cow and from the 2 BLV-seronegative cows remained seronegative. These results were interpreted to indicate that the quantity of infective lymphocytes passed during injection with common needles is too small to induce infection.

In vitro viral expression as a criterion for development of control procedures for enzootic bovine leukosis.

In a university beef herd of 304 cattle in which six died of lymphosarcoma between 1980 and 1984, 77% of the Angus and 26% of the Charolais cattle were determined to be infected with bovine leukemia virus (BLV). Changes in iatrogenic procedures were initiated as early control measures. In vitro viral expression (VE) was used as a criterion to identify cattle for subsequent segregation or culling. This involved determinations of percentages of BLV-associated lymphocyte profiles among thin-sectioned Ficoll-Paque-isolated blood lymphocytes that were processed into plastic after culture for 48 h. Cattle retained until completion of nutritional studies or as breeding stock were separated into two groups. The BLV-seronegative cattle, BLV-seropositive cattle with 0% VE, and BLV-seropositive cattle with 1% to 4% VE were placed in group 1. Seropositive cattle with greater than or equal to 5% VE were placed in group 2. In 1985, evaluation of in vitro VE in 108 mature BLV-seropositive cattle retained for breeding revealed 36 (33%) had no observable VE. In 1986, 58 of 108 cattle were available to be reexamined, and 21 (36%) had 0% VE in both years. The VE expression values for individual cattle were generally comparable over the 2-year period. Of 48 initial seronegative breeding stock housed in group 1 with BLV-seropositive cattle with low or no VE, 21 (44%) seroconverted during 1985 to 1986. A positive correlation of 0.585 was found between VE and age-related absolute lymphocyte number.

Infectivity in sheep of blood lymphocytes from bovine leukemia virus-infected cows with different nuclear pocket prevalences.

The infectivity for the bovine leukemia virus (BLV) of bovine blood lymphocytes, with varying lymphocyte nuclear pocket (LNP) prevalence, was studied by intradermal injection of buffy coat leukocytes from cows into sheep. Thirty-five sheep were assigned to 3 groups of 9, 11, and 15, respectively, as recipients of blood leukocytes from individual cows as follows: 9 leukocyte donor cows included 3 BLV-seropositive cows with high (greater than or equal to 2.0%) LNP prevalence (group 1); 3 BLV-seropositive cows with low (less than 0.5%) LNP prevalence (group 2); and 3 BLV-seronegative cows with increased (greater than or equal to 0.5%) LNP prevalence (group 3). The 9 sheep in group 1 became BLV-seropositive by postinoculation day (PID) 57 as determined by the agar-gel immunodiffusion test; 2 of 11 sheep in group 2 became agar-gel immunodiffusion seropositive by PID 40; none of the 15 sheep of group 3 became seropositive by PID 92. Seemingly, there is a real difference in infectivity among BLV-seropositive cattle which is related to LNP prevalence, and seronegative cattle with increased LNP prevalence may be noninfectious, ie, were not carrying covert BLV virogene.

In vitro stimulation of bovine peripheral blood lymphocytes: suppression of phytomitogen and specific antigen lymphocyte responses by aflatoxin.

The effects of aflatoxin B1 on responses of the peripheral blood lymphocytes (PBL) of 2 normal animals to phytohemagglutinin, concanavalin-A, and pokeweed mitogen and of the PBL of 2 Mycobacterium bovis-infected animals to phytohemagglutinin and purified protein derivative of M bovis (PPD) were studied. Aflatoxin concentrations of greater than or equal to 10 microgram/ml significantly suppressed the lymphocyte response of normal animals to the phytomitogens. Lymphocyte response of M bovis-infected animals to specific antigen PPD was significantly suppressed at aflatoxin concentration of 0.5 microgram/ml. Fifty- to 100-fold higher concentrations of aflatoxin were required to produce 50% suppression of lymphocyte response to phytomitogens, as compared with that produced to PPD.

Evaluation of the stable fly (Stomoxys calcitrans) as a vector of enzootic bovine leukosis.

Experiments reported here were directed at 2 questions: (1) Can the stable fly (Stomoxys calcitrans) transmit enzootic bovine leukosis? (2) Could early viremia augment the probability of transmission by this insect? In one vector experiment, calves and bovine leukemia virus (BLV)-infected cows were housed with and without stable flies. The calves were monitored serologically during a 3-month postexposure period, using the agar gel immunodiffusion test. All fly-infested and fly-free calves remained BLV-seronegative. For a second vector experiment, donor calves, newly injected with blood from BLV-infected cows with high virus expression, were tethered alternately between uninoculated, weaned BLV-seronegative calves. These groups were housed with or without flies in 2 replicate trials. The inoculated calves from the first replicate seroconverted at 16 and 23 days after inoculation; the inoculated calves from the second replicate seroconverted at 11, 16, 16, and 37 days after inoculation. All uninoculated calves remained BLV-seronegative. In a manual transmission experiment, 50 unfed stable flies were allowed to complete a meal on each of 3 BLV-seronegative calves after feeding on a BLV-seropositive cow with high (42%) virus expression. One control calf was injected with blood from the cow. Seroconversion occurred in the control calf and 1 calf on which flies were given access. A scanning electron microscopic study was made of the everted and closed mouth parts of the stable fly. Given the lymphocyte count in blood from the cow used in the manual vector transmission experiment, it was calculated that 3,950 mouth part volumes would be necessary to transmit BLV.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of the 14/20 centric fusion chromosomal aberration in US Simmental cattle.

Cytogenetic evaluation was made on 353 Simmental cattle (166 male, 187 female) from 113 herds in 26 states. One hundred thirty-eight (39%) were found to be heterozygous-positive for the 14/20 centric fusion chromosomal translocation, including 41 (25%) males and 97 (52%) females. One submitted heparinized blood sample from a Simbrah bull was found to be positive for 14/20 and 1/29 centric fusions. Sampling, which was based on requests, was highly selective. Thus, the 39% prevalence found was not representative of 14/20 centric fusion in the national Simmental breed. On the basis of our findings, cytogenetic evaluation of breeding stock was consistent with modern management practice.

X-Chromosome monosomy (37,XO) in a Burmese cat with gonadal dysgenesis.

A 37,XO-chromosome complement was detected in a 21/2-year-old sable Burmese cat examined because of primary anestrus. The cat was smaller than its littermates; other somatic abnormalities associated with the XO karyotype in other species were not present. The ovaries, which did not respond to gonadotropin stimulation, contained inactive germinal epithelium (lacking follicles and primordial germ cells), which was similar to that of adult human patients with XO-gonadal dysgenesis.

Diagnosis of freemartinism in cattle: the need for clinical and cytogenic evaluation.

A total of 727 blood samples from female calves born co-twin to male calves were examined cytogenetically for freemartinism between 1978 and 1992. Six hundred calves (82.5%) were determined to be freemartins, and 127 (17.5%) were determined not to be freemartins. The percentage of calves determined not to be freemartins was substantially higher than the 8% reported for an unselected population of female co-twins. We concluded that some obvious freemartins were eliminated prior to submission of samples for confirmatory cytogenetic diagnosis, and that only a small percentage of the estimated 93,000 female calves born co-twin to male calves annually are so examined. Therefore, probably a large number of female co-twins that are not truly freemartins are sold to slaughter every year. We propose that obvious freemartins be identified by use of the vaginal-length test and that the remaining clinically questionable calves be differentiated cytogenetically. This combination of procedures could prevent unnecessary economic losses and preserve important genetic material. Three animals with chromosomal anomalies were found during examination of samples for freemartinism. Cytogenetic evaluation for freemartinism thus offers the added value of simultaneous surveillance for cytogenetic aberrations in male and female cells of a sample.

Triploidy (117,XXX) in a stillborn canine pup conceived with frozen semen.

Analysis of skin fibroblast cultures from a deformed stillborn female Alaskan Malamute pup revealed a 3n = 117,XXX (normal, 2n = 78,XX) chromosome count. The triploid pup was delivered by cesarean section 5 days after estimated date of parturition, because the bitch failed to start labor. The bitch had been inseminated with thawed frozen semen deposited into the lumen of the uterus approximately 4 days after ovulation. Gross anatomic abnormalities of the pup included omphalocele, diaphragmatic hernia, persistent right aortic arch, atresia ani, and no right forelimb distal to the scapula. The pup also had arthrogryposis of the left carpus, kyphosis of the thoracic vertebrae, widely separated cranial sutures, open fontanelles, hydrocephalus, and cleft palate. Suspected cause of the triploidy was dispermy of an aged oocyte after intrauterine deposition of the thawed frozen semen. Numeric chromosome abnormalities may be causes of fetal deformity or death that can be detected by fetal karyotype.

Cytogenetic survey of Holstein bulls at a commercial artificial insemination company to determine prevalence of bulls with centric fusion and chimeric anomalies.

OBJECTIVE: To determine prevalence of Holstein bulls with chromosomal anomalies, particularly the 1/21 centric fusion (CF), at a commercial artificial insemination (AI) company in the United States. DESIGN: Cross-sectional cytogenetic prevalence study. ANIMALS: All 606 Holstein bulls at a commercial AI company were cytogenetically screened to detect CF, chimerism, and other chromosomal abnormalities. PROCEDURE: Lymphocytes from heparinized blood samples were cultured by standard cytogenetic techniques, and chromosome spreads were prepared for microscopic examination. Chromosomal abnormalities were detected by examining 10 chromosome spreads per bull. Pedigree analysis was performed. RESULTS: None of the bulls had any type of CF. However, 6 bulls were identified as chimeras (i.e., contained lymphocytes with male [XY] and female [XX] chromosomes). One bull was sire or maternal grandsire to 85 of the bulls tested, and 739 of 1,212 (61%) sire and maternal-grandsire possibilities were accounted for by just 18 bulls. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of these results supports previous indications that CF is extremely rare in Holstein bloodlines available commercially via AI in the United States. However, chimeric bulls are more common, and they reportedly have decreased reproductive performance. Therefore, identification of chimeric sires in the AI facility reported here and the possibility of de novo onset of CF at any time indicates that early cytogenetic screening should be encouraged for prospective bulls intended for use in AI programs.

Prolonged proestrus in a bitch with X chromosomal monosomy (77,XO).

A stunted Miniature American Eskimo bitch that had signs of proestrus, which persisted for almost 8 months, had a 77,XO karyotype. Despite signs of proestrus, the ovaries were small and fibrous, and there was no evidence of ovarian follicle development or corpora lutea. Except for its juvenile appearance, the rest of the reproductive tract was grossly normal. Clinical signs in this bitch were similar to those in human beings with Turner's syndrome.