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Biomedical subjects

T Tran

Publications and source records attributed to T Tran.

At least 109 records · Page 6Linked to original sources
PubMed1993

Estrus and pregnancy rate of dairy cows given one or two doses of prostaglandin F2 alpha 8 or 24 hours apart.

A total of 329 cows was used in 2 experiments to study the effect of PGF2a given 8 or 24 h apart on the number of cows observed in estrus within 7 d and the pregnancy rate to a single insemination at this time. In Experiment 1, 233 cows were divided into 2 groups. Cows in Group 1 (n = 117) were treated twice with 25 mg, im of PGF2a (0 and 8 h) while cows in Group 2 (n = 116) were treated only once (0 h). In Experiment 2, 96 cows were divided into 2 groups. Cows in Group 1 (n = 49) were treated twice with 25 mg, im of PGF2a (0 and 24 h) while cows in Group 2 (n = 47) were treated only once (0 h). In Experiment 1, blood samples were obtained from cows in both groups on Days 0 and 2. However, in Experiment 2, blood samples were obtained from cows in both groups only on Day 0. Plasma progesterone concentration was determined using radioimmunoassay. Cows in both experiments were observed for estrus within 7 d of treatment and were inseminated within 12 h of the observed estrus. In Experiment 1, more cows in Group 1 were observed in estrus within 7 d than in Group 2 (P <0.03). In Experiment 2, there was no significant difference in the number of cows in both groups that were observed in estrus within 7 d. However, the interval from treatment to the first observed estrus for cows not observed in estrus within 7 d was significantly longer in cows treated at 0 and 24 h compared with the cows treated once at 0 h. In both experiments, the pregnancy rate for cows inseminated within 7 d was similar for cows in all groups. From the results of this study, it is concluded that treatment of dairy cows with 2 luteolytic dosages of PGF2a at an 8-h interval resulted in more cows being observed in estrus than at a 24-h interval.

Journal Article↗
PubMed1993

The effect of gossypol in cottonseed meal on performance and on hematological and semen traits in postpubertal Brahman bulls.

The effects of a cottonseed meal diet containing high levels of free gossypol on hematological traits, including erythrocyte osmotic fragility and semen characteristics, were examined during an 11-week period. Eight Brahman bulls were randomly assigned to 1 of 2 groups. The control group (n=4) was fed a mixture of soybean meal and corn. The treated group (n=4) was fed a mixture of cottonseed meal and corn. Both groups were allowed hay free choice. The treated group consumed 8.2 g of free gossypol per bull per day. The percentage of normal spermatozoa was lower (P<0.01) in the treated than in the control group from Week 5 (49+/-9.8 vs 83+/-3.2%), which was primarily influenced by changes in mid piece morphology in the treated bulls. Erythrocyte osmotic fragility was higher (P<0.001) in the treated than in the control group over the entire study period, although group values diverged more acutely from Week 7 of treatment. Sperm motility was lower (P=0.04) in treated bulls than in control bulls at Week 9 (52+/-9.8 vs 82+/-6.2%). These data suggest that concurrent discernable changes in bull erythrocyte osmotic fragility and in semen characteristics can occur following commencement of a diet containing 8.2g of free gossypol per day.

Journal Article↗
PubMed1993

Increased pulmonary perfusion worsens ventilation-perfusion matching.

BACKGROUND: Severe exercise and administration of vasopressors may adversely affect pulmonary gas exchange in humans. The role of increases in pulmonary perfusion in worsening ventilation-perfusion (VA/Q) relationships is unclear, however, because concomitant changes in ventilation and alveolar gas composition occur. The purpose of this study was to determine whether increasing of lobar blood flow increased VA/Q heterogeneity in the absence of changes in respiratory parameters. METHODS: Six pentobarbital-anesthetized dogs underwent bilateral thoracotomies, left upper lobectomy, and placement of an electromagnetic flow probe on the left lower lobe (LLL) pulmonary artery, and catheters were inserted into the LLL pulmonary artery distal to the flow probe and confluent trunk of the LLL pulmonary vein. A bronchial divider was inserted to allow separate ventilation of the right lung and LLL. Blood flow to the LLL (QLLL) was increased in random order to two and three times baseline blood flow by opening an arteriovenous fistula and partially occluding the right pulmonary artery. Minute ventilation and alveolar PCO2 of the lobe were unchanged due to use of constant tidal volume and respiratory rate and inspiration of variable amounts of carbon dioxide. VA/Q distributions of the LLL were obtained using the multiple inert gas elimination technique. The tracer inert gas arterial-alveolar difference ([a-A]D) area was used to assess VA/Q mismatch. RESULTS: Increasing QLLL increased mean pulmonary artery pressure in the LLL (LLL Ppa). The PO2 of the LLL pulmonary venous blood remained unchanged, as the mixed venous oxygen tension (PvO2) was markedly increased. VA/Q inequality was increased, indicated by a 40% increase in the [a-A]D area when QLLL was increased to two times greater than baseline QLLL and a 58% increase in the [a-A]D area with three times greater than baseline QLLL. The [a-A]D area was highly correlated with the lobar blood flow (r = 0.97) and LLL Ppa (r = 0.97). CONCLUSIONS: Marked increases in lobar blood flow and Ppa worsened pulmonary gas exchange. The degree of impairment was correlated with the degree of increase in lobar perfusion. However, increased lobar perfusion did not affect LLL pulmonary venous blood oxygenation because the decrease in PO2, due to increased VA/Q mismatch, was opposed by an increase in PO2, due to increased PvO2.

Animals↗
PubMed1993

Eosinophil cationic granule proteins impair thrombomodulin function. A potential mechanism for thromboembolism in hypereosinophilic heart disease.

Thromboembolism is a prominent but poorly understood feature of eosinophilic, or Loeffler's endocarditis. Eosinophil (EO) specific granule proteins, in particular major basic protein (MBP), accumulate on endocardial surfaces in the course of this disease. We hypothesized that these unusually cationic proteins promote thrombosis by binding to the anionic endothelial protein thrombomodulin (TM) and impairing its anticoagulant activities. We find that MBP potently (IC50 of 1-2 microM) inhibits the capacity of endothelial cell surface TM to generate the natural anticoagulant activated protein C (APC). MBP also inhibits APC generation by purified soluble rabbit TM with an IC50 of 100 nM without altering its apparent Kd for thrombin or Km for protein C. This inhibition is reversed by polyanions such as chondroitin sulfate E and heparin. A TM polypeptide fragment comprising the extracellular domain that includes its naturally occurring anionic glycosaminoglycan (GAG) moiety (TMD-105) is strongly inhibited by MBP, whereas its counterpart lacking the GAG moiety (TMD-75) is not. MBP also curtails the capacity of TMD-105 but not TMD-75 to prolong the thrombin clotting time. Thus, EO cationic proteins potently inhibit anticoagulant activities of the glycosylated form of TM, thereby suggesting a potential mechanism for thromboembolism in hypereosinophilic heart disease.

Aged↗
PubMed1993

Scaling pigeons' choice of feeds: bigger is better.

Preferences of hungry pigeons among 10 grains and pellets were analyzed using a Thurstone scaling procedure. The recovered scales were positively correlated with size of the feed. The correlations improved when the Thurstonian assumption of equal-sized discriminal dispersions (Case V) was replaced with the assumption of proportional-sized dispersions (Case VI), as entailed by Weber's law. The correlations weakened when the experiments were conducted with the pigeons close to their free-feeding weights, where the probability of sampling alternative grains increased. In the final experiment, exposure to a large pellet shifted the preferences between two smaller pellets.

Animals↗
PubMed1993

Influence of an abrupt change in diet on antroduodenal myoelectric activity in lactating cattle.

Effects of a change from a diet composed primarily of forage to a diet composed primarily of concentrate on abomasal antral and duodenal motility were assessed in 5 lactating Holstein cows. Antroduodenal motility was measured by use of 8 silver electrodes sutured to the abomasum and duodenum, and abomasal emptying was assessed by continuous measurement of intraduodenal pH. Both diets were fed to achieve a daily dry matter intake of 2.7 kg/100 kg of body weight. The abrupt change in diet did not alter antroduodenal myoelectric activity or abomasal emptying. Initiation of phase III of the migrating myoelectric complex in the proximal portion of the duodenum corresponded with a decrease in abomasal antral spiking activity and an increase in intraduodenal pH. Results suggest that a high concentrate diet alone does not adversely affect antroduodenal motility in adult dairy cattle.

Abomasum↗
PubMed1992

Factors that influence passive transfer of immunoglobulins in foals.

Effects of farm management, breed, mare age, gestation duration, and climatologic factors on colostral specific gravity, colostral IgG concentration, and foal serum IgG concentration were evaluated. Climatologic variables measured were daily maximal, minimal, and mean air temperature, precipitation, average relative humidity, and total solar radiation. Presuckle, postpartum colostrum samples were collected from 140 Standardbred, 94 Thoroughbred, and 59 Arabian mares from January through June during 1985 and 1986. Thoroughbred (farm A, n = 61; farm B, n = 33) and Arabian (farm C, n = 45; farm D, n = 14) mares were located in Ocala, Fla; Standardbred mares (farm E) were in Montgomery, NY. Mares from farms A, B, D, and E foaled in box stalls, and mares from farm C foaled in sand paddocks. Mares with premature lactation greater than 12 hours were not included in the study. Foals were clinically normal at birth and suckled colostrum without assistance within 2 hours of parturition. Specific gravity of presuckle colostrum samples was measured by use of an equine colostrometer. Blood samples were collected 18 hours after parturition from 253 of the 293 foals (n = 45, 25, 32, 13, 138 on farms A through E, respectively) to determine serum concentration of IgG. The IgG concentrations in colostrum and serum were measured by single radial immunodiffusion. Data were analyzed by multiple regression or chi 2 analysis. The most important determinants of foal serum IgG concentration were the IgG content and specific gravity of presuckle colostrum samples (P less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Husbandry↗
PubMed1992

Analysis of Acanthurus triostegus for marine toxins by the stick enzyme immunoassay and mouse bioassay.

The herbivorous convict tang or surgeon fish, Acanthurus triostegus, collected at different locations in the Hawaiian islands, was analyzed for toxicity using a mouse bioassay and a stick enzyme immunoassay (S-EIA) developed to detect ciguatoxin and closely related polyethers. Results of the S-EIA test indicated that about 94% of the samples gave negative readings, while 6% of the fish were positive and thus considered toxic. Fish samples from each location were pooled and the flesh and viscera were successively extracted with hexane, methanol, and water and tested in a mouse bioassay. About one-third of the methanol soluble fractions killed mice within 20 min, 70% killed within 4 hr, and 85% killed within 48 hr. About 40% of the hexane-soluble fractions killed mice within 24 hr and 55% killed within 48 hr. The water-soluble extracts of the flesh and viscera of fish taken from three locations showed relatively high toxicity. Common symptoms for all fractions included convulsions and jumping (especially just prior to death), respiratory distress, hind leg to complete paralysis, loss of body tone, and tremors. Analysis of the data suggests that in the flesh and viscera of A. triostegus there are at least three different nervous system-type toxins, most of which did not appear to react to the S-EIA test.

Animals↗
PubMed1992

Conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotrophin releasing hormone and/or prostaglandin F2 alpha.

This study was designed to determine conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotrophin releasing hormone (GnRH) and/or prostaglandin F2 alpha (PGF2alpha). A total of 2352 cows was randomly assigned to six groups. Cows in Groups 1 to 5 were palpated per rectum to determine the presence of a corpus luteum (CL) on the ovary, and blood samples were obtained for the determination of plasma progesterone (P4) concentrations. Cows with a CL and P4 concentrations >1 ng/ml were treated (Day 0) with PGF2alpha (25 mg, i.m.) and were observed for estrus. Cows in estrus prior to 72 hours after treatment (Group 5, n = 106) were bred, but were not treated. Cows not observed in estrus by 72 hours were divided into four remaining groups, were bred between 72 and 80 hours and were assigned as follows: Cows in Group 1 (n = 203) were not treated; Cows in Group 2 (n = 200) were treated with GnRH (100 ug, i.m.); Cows in Group 3 (n = 201) were treated with PGF2alpha (25 mg, i.m.); and cows in Group 4 (n = 202) were treated with both GnRH and PGF2alpha. Cows in Group 6 (n = 1440) were not treated with PGF2alpha on Day 0 and were estrual cows that were bred on days when cows in Groups 1 to 5 were time-inseminated. The percentage of cows in all groups pregnant at 45 to 50 days after one insemination was compared using analysis of variance (P<0.05). The conception rate of cows in Group 2 was significantly higher than that of cows in Groups 1 to 4. There was a significant group-by-season interaction. Cows treated with GnRH during the spring had a higher conception rate than at other times of the year. Conception rates of cows in Groups 1 to 4 that were inseminated during the summer were low and not significantly different from each other. Conception rates of cows in Groups 5 and 6 inseminated during the summer were not significantly different from each other, but were significantly higher than that of cows in Groups 1 to 4 that were inseminated during the summer.

Journal Article↗
PubMed1991

Experimental Borrelia burgdorferi infection in inbred mouse strains: antibody response and association of H-2 genes with resistance and susceptibility to development of arthritis.

We have investigated the specific humoral immune response and its correlation to the development of disease after experimental inoculation of B. burgdorferi in different inbred strains of mice. All mouse strains tested showed high levels of specific IgM antibodies during the initial 10 days of infection. Specific IgG antibodies predominantly of the IgG2a, IgG2b and IgG3 isotypes were found in increasing amounts by 14 days post infection. Antibody titers peaked at days 65 and 110. Particularly low titers of specific IgM and/or IgG antibodies were detected in sera of AKR/N and B10.BR mice. Antibodies specific for numerous B. burgdorferi antigens including the outer surface proteins A (31 kDa) and B (34 kDa) and a protein(s) of molecular mass of approximately 40 kDa, most probably 41 kDa (flagellin) and/or 39 kDa (p39), were induced in all inbred mouse strains within 2 weeks inoculation albeit in varying concentrations. Later during infection, the patterns of antibody specificities were much more complex. With regard to development of disease all strains of mice tested fall into three groups: (a) mice of H-2k haplotype (AKR/N, C3H/HeJ, C3H/HeN, B10.BR) developed a chronic progressive arthritis in the tibiotarsal joints, (b) mice of H-2 haplotypes, H-2b (C57BL/6), H-2j (B10.WB), H-2r (B10.R111) and H-2s (B10.S) developed arthritis of variable duration and intensity which was not progressive and (c) mice of H-2d haplotype (BALB/c, DBA/2, C.B-17, B10.D2, Cal.20), irrespective of their background genes or Igh allotype, showed no clinical signs of arthritis at any time point following inoculation of B. burgdorferi organisms. The finding of similar patterns of apparently protective antibodies in all mouse strains tested together with the striking association between the H-2d haplotype and resistance, and between the H-2k haplotype and the occurrence of B. burgdorferi-induced arthritis suggest a critical role of T cells in the development of the disease in mice.

Animals↗
PubMed1991

Uptake of bilirubin glucuronides by isolated rat hepatocytes.

The uptake of bilirubin diglucuronide (BDG) into isolated rat hepatocytes was investigated in order to characterize the mechanism by which bile pigments are transported by the liver. The BDG uptake by hepatocytes was saturable. The uptake was inhibited by bilirubin, sulfobromophthalein, and bilirubin monoglucuronide, but not by taurocholate. The uptake was not affected by replacement of sodium with other cations except for choline. Only when sodium was replaced with choline, was significant decrease in uptake observed. When chloride was replaced with nitrate, BDG uptake decreased, but it was not changed by replacement with sulfate. Metabolic inhibitors did not affect BDG uptake significantly. Thus bile pigments share a common sodium-independent and electrogenic potential-dependent transporter in liver cell membranes. A high concentration of albumin interferes with BDG uptake.

Animals↗
PubMed1991

Aging effects on heart rate variation.

Heart rate variation was studied in 56 healthy subjects from ages 20-81 while supine and standing during spontaneous and metronome breathing. Time domain analyses revealed no age effect on supine heart rate but standing heart rate decreased with aging (p less than .008). The SD of R-R intervals decreased with increasing age in both positions (p less than .001). Frequency domain analysis (Fast Fourier Transformation of R-R interval data) showed total spectral content to decrease with aging (p less than .001). Both high frequency (0.20-0.32 Hz) and low frequency (0.04-0.12 Hz) content were reduced with aging (p less than .001). The ratio of high to low frequency content, however, was not affected by age in the supine position nor were changes in this ratio in response to standing during spontaneous breathing. Although the absolute increase in low frequency content upon standing was less with aging (p less than .001), the percent increase in low frequency content was not related to age. Metronome breathing decreased total spectral content (p less than .001) but increased high frequency content, especially in younger subjects (p less than .03). In response to standing, greater proportional and absolute decreases in high frequency content occurred in younger subjects resulting in age differences in the changes in ratios of high to low frequency content with standing during metronome breathing. In summary, decreased heart rate variation was seen with aging, but the balance between parasympathetic and beta-adrenergic input at rest and in response to postural changes does not appear to be influenced by age during spontaneous breathing. Metronome breathing altered spectral content within subjects and produced age-related differences in responses to postural maneuvers not seen during spontaneous breathing.

Adult↗
PubMed1991

Identification and opsonic activity of immunoglobulins recognizing Streptococcus zooepidemicus antigens in uterine fluids of mares.

A direct ELISA was used to measure immunoglobulin (Ig) isotypes G, Gt, A, and M recognizing Streptococcus zooepidemicus epitopes in uterine lavage fluids collected during the early post ovulatory period. A S. zooepidemicus isolate, used as the plate antigen in this assay, was inoculated into the uteri of 8 mares (3 resistant and 5 susceptible to endometritis) at oestrus prior to ovulation during Oestrous Cycles 1, 3 and 5. Resistant mares aged 2-5 years were nulliparous, with clinically normal reproductive tracts as determined by physical examination, bacteriological culture of the uterus, and endometrial biopsy. Susceptible, pluriparous mares, aged 16-24 years, had histories of endometritis and infertility and had chronic endometrial inflammatory changes detected by uterine biopsy. On Post ovulation Day 3 during Oestrous Cycle 1, on the day of ovulation during Oestrous Cycle 3 and on Post Ovulation Day 5 during Oestrous Cycle 5, uterine swab specimens were obtained for bacteriological culture and the uterus was irrigated with 50 ml sterile physiological saline solution containing tracer amounts of 125I-labelled human serum albumin (HSA). The titre of each Ig isotype was determined and the amount in uterine effluents was calculated from the dilution of the 125I-HSA. Total IgG concentration in uterine effluents was measured by radial immunodiffusion. Uterine fluids, either unheated or heated 30 min at 56 degrees C, were used to opsonize the S. zooepidemicus isolate in an assay of luminol-enhanced neutrophil chemiluminescence (CL). Mean peak CL generated was compared with CL generated by a control serum. Streptococcus zooepidemicus was isolated from 10 of 15 (67%) uterine specimens from susceptible mares.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A comparison of the effects of scopolamine and diazepam on acquisition and retention of inhibitory avoidance in mice.

Administration of either the muscarinic antagonist scopolamine or the benzodiazepine diazepam prior to training produced a dose-dependent impairment in the retention of one-trial inhibitory avoidance training in mice. To investigate the nature of this drug effect, the effects of scopolamine and diazepam were subsequently assessed on both acquisition and retention of inhibitory avoidance using a multiple-trial, training-to-criterion procedure. The training was conducted using either continuous trials in which the mouse was free to shuttle back and forth between shock and safe compartments or discrete trials in which the mouse was moved from the shock compartment of the safe compartment at the start of each trial. In either case, training continued until the mouse refrained from crossing into the shock compartment for a specified length of time on a single trial. Scopolamine (1.0 mg/kg) administered before training significantly increased the number of trials required to attain criterion, but did not affect retention when these mice were tested 2, 16, or 28 days later. In contrast, diazepam (1.0 mg/kg) did not significantly alter the number of trials necessary to reach criterion, but impaired retention of the inhibitory response in mice trained using discrete trials. The differences in the amnestic effects of scopolamine and diazepam revealed by this detailed analysis suggest that diazepam does not impair inhibitory avoidance performance through an effect on cholinergic function.

Animals↗