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Biomedical subjects

L W Johnson

Publications and source records attributed to L W Johnson.

At least 91 records · Page 5Linked to original sources
PubMed1988

Intravenous leiomyomatosis: a rare cause of right sided cardiac obstruction.

Intravenous leiomyomatosis involving the right side of the heart is an unusual cause of outflow obstruction. Evaluation of the patient should be directed not only at intracardiac chambers but also at the inferior vena cava. This should include angiography and MRI or CAT scanning. Echocardiography is an important contributory investigation. Surgical therapy should be directed at complete removal of the tumor as recurrence has been reported if a less than complete resection has been performed. Hormonal manipulation has been attempted with variable results.

Cineangiography↗
PubMed1988

Neutral amino acid transport systems of microvillous membrane of human placenta.

Placental transport produces concentrations of amino acids in fetal blood greater than those of maternal blood. Competitive inhibition studies of zwitterionic amino acid transport in isolated vesicles from the microvillous (maternal facing) plasma membranes of syncytiotrophoblast defined three transport systems: 1) a sodium-dependent system that supports methylaminoisobutyric acid (MeAIB) transport and has the characteristics of an A system; 2) a sodium-independent system with a high affinity for leucine and other amino acids with branched or aromatic side chains; and 3) a sodium-independent system with a preference for alanine as a substrate. The two sodium-independent systems could be further discriminated by marked specificity for trans stimulation with alanine or with leucine. System ASC, known to be present in whole placenta, and the neutral brush-border or imino systems of other polarized epithelia were apparently absent. Kinetic characteristics of the A system make it the probable primary driving force for concentrative transfer of its substrate amino acids to the fetus. Characteristics of the high-affinity leucine system demonstrated that it is saturated by normal serum leucine concentrations. Regulation of either system has the potential to alter placental amino acid uptake and transfer to the fetus.

Alanine↗
PubMed1988

Pulmonary hypertension in isolated aortic stenosis. Hemodynamic correlations and follow-up.

The clinical, hemodynamic, and angiographic data on 92 patients with severe isolated aortic stenosis were reviewed to determine the incidence and mechanism of pulmonary hypertension. The status of each of these patients was determined 1 to 8 years after diagnosis by cardiac catheterization. Patients were divided into three groups on the basis of the pulmonary artery systolic pressure: group 1 (less than or equal to 30 mm Hg), 46 patients; Group 2 (31 to 50 mm Hg), 31 patients; and Group 3 (greater than 50 mm Hg), 15 patients. The prevalence of pulmonary hypertension was 50% (46/92) and that of severe pulmonary hypertension, 16% (15/92). There was no significant difference in age, aortic valve gradient, or valve area among the three groups. There was a significant positive correlation in left ventricular end-diastolic pressure (group 1, 15.5 +/- 7.2 mm Hg; group 2, 23.3 +/- 8.1 mm Hg; and group 3, 29.5 +/- 5.8 mm Hg; R = 0.56, p less than 0.01). There was also a significant negative correlation in left ventricular ejection fraction (group 1, 67.5% +/- 14%; group 2, 62.3% +/- 13.8%; and group 3 49.9% +/- 18.3%; R = 0.43, p less than 0.01). Of the 92 patients, 85 had aortic valve replacement with four (4.7%) hospital deaths. Follow-up showed excellent symptomatic relief in all three groups. Thirteen of the 15 patients in group 3, with severe pulmonary hypertension, had aortic valve replacement. There were no hospital deaths and only one noncardiac death at follow-up in Group 3 patients, and 11 of the 12 surviving patients were in New York Heart Association functional class I. We conclude that pulmonary hypertension is common in isolated aortic stenosis and is related to an elevated left ventricular end-diastolic pressure, frequently with preserved systolic function. Surgical results are excellent.

Aortic Valve Stenosis↗
PubMed1987

Attenuation of Babesia bovis by in vitro cultivation.

A virulent strain of Babesia bovis was adapted to grow in erythrocyte culture in the presence of equine serum and in lieu of bovine serum. Four splenectomized calves inoculated with the adapted strain, 429, developed hematologic signs of infection and a low grade fever, but remained free of central nervous system (CNS) signs and recovered. All of six control animals inoculated with a virulent strain reacted severely and five showed CNS signs and died. The calves injected with the attenuated strain were solidly immune when challenged with the virulent strain at 44 or 78 days after vaccination.

Animals↗
PubMed1987

Pulmonary hypertension in severe aortic stenosis. Incidence, mechanisms, clinical and surgical implications.

Pulmonary arterial hypertension in aortic stenosis (AS) is considered uncommon, and the possible mechanisms involved in its insorgence are only speculative. We analyzed a group of 95 patients with severe AS (mean systolic gradient greater than or equal to 50 mmHg and/or aortic valve area less than or equal to 0.7 cm2) studied by standard hemodynamic techniques. In the study group the incidence of pulmonary hypertension was 50.5%. We divided the overall population in: Group I (47 patients), with systolic pulmonary artery pressure (PAP) less than or equal to 30 mmHg; Group II (33 patients), with moderate hypertension (PAP 31-50 mmHg); Group III (15 patients), with severe hypertension (PAP greater than 50 mmHg). Subjects with pulmonary hypertension were slightly older, and had more severe obstruction to left ventricular (LV) outflow. Impairment of LV diastolic function in the presence of pulmonary hypertension was expressed by a highly significant increase of LV end-diastolic pressure (p less than .001); reduced ejection performance was represented by a significant decrease of ejection fraction (p less than .01). Pulmonary vascular resistances also appeared to be increased. The correlation between variables showed PAP to be strongly correlated in a positive way to the LV end-diastolic pressure, and in an inverse way to the LV systolic performance (p less than .001 for both). Less striking was the correlation of pulmonary vascular resistances to LV diastolic and systolic function: a reactive and reversible vasoconstriction seemed likely. Surgery was not performed in 8 of the 95 patients: 5 of them died shortly after diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Anaplasma marginale, Eperythrozoon wenyoni: lectin reactions with bovine erythrocytes.

Normal bovine erythrocytes were agglutinated with four of five lectins specific for different oligosaccharides. The order of reactivity was wheat germ greater than ricin greater than soybean greater than peanut. Concanavalin A did not agglutinate normal bovine erythrocytes. After neuraminidase treatment of normal bovine erythrocytes, each lectin agglutinated the cells with decreased concentrations of lectin, verifying that partial removal of sialic acid exposes more of each lectin's binding sites or alters the binding site such that fewer molecules of lectin are required to initiate agglutination. A change in agglutination of erythrocytes using soybean agglutinin and peanut agglutinin occurred when cells were obtained from cattle infected with Eperythrozoon wenyoni. The results suggested that an alteration in erythrocyte membranes occurred as a result of this infection as manifested by the increased recognition of both the soybean agglutinin and peanut agglutinin receptor carbohydrates. A similar effect was indicated with erythrocytes obtained during an acute Anaplasma marginale infection; however, an ensuing reticulocytosis masked the effect, requiring the use of fluoresceinated lectins to verify that increased binding of each lectin occurred with infected cells when compared to normal cells.

Anaplasmataceae Infections↗
PubMed1986

Pneumonia in goats following administration of live and heat-killed Pasteurella haemolytica.

Six of 7 and 3 of 4 goats inoculated with live and heat-killed P. haemolytica (biotype-T), respectively, had pneumonia at necropsy. Clinically, the pneumonia was only detected in 8 of 9 goats with diseased lungs. One goat died of a fibrinous pneumonia which was associated with a profuse growth of both P. haemolytica (biotype-T) and P. multocida and a limited growth of Escherichia coli from the lungs. In the remaining 8 goats with lung lesions, the pneumonia was of the proliferative type, with only some showing the exudative feature. Five of these goats (including 3 controls) had bacteriologically sterile lung lesions, while the other 3 yielded P. haemolytica (biotype-T) and in one of them, chlamydia were also isolated. P. haemolytica (biotype-T) and P. multocida were isolated from 1 of 2 goats with normal lungs.

Animal Diseases↗
PubMed1986

Chemoprophylactic activity of imidocarb, diminazene and oxytetracycline against Babesia bovis and B. bigemina.

Splenectomized calves treated with imidocarb, diminazene, and oxytetracycline were exposed to Babesia bigemina and B. bovis stabilates at various time intervals following treatment to evaluate prophylactic efficacy. Diminazene showed no residual activity against a B. bigemina challenge given 54 days after treatment. Oxytetracycline appeared responsible for an increased incubation time when given 2 days prior to B. bigemina exposure. Imidocarb showed marked prophylactic efficacy against both B. bigemina and B. bovis. Treatment with 1 or 2 mg kg-1 imidocarb, followed by Babesia exposure on the day of treatment, 7 days after treatment, then every 14 days for 91 days, delayed patent B. bigemina infections for 49 days and patent B. bovis infections for 42 days. Imidocarb at 4 or 5 mg kg-1, followed by similar Babesia exposures, delayed patent B. bovis infections for 68 days, and delayed B. bigemina for 81-103 days, and in some instances prevented infections. The delayed onset of infection due to either B. bigemina or B. bovis, following imidocarb treatment was accompanied by a significantly milder clinical response. Calves not responding to the primary challenge were fully susceptible to stabilate challenge 196 days after treatment. Calves experiencing a mild clinical response to B. bovis following imidocarb treatment and exposure failed to show any signs of response to a 196-day challenge exposure. Calves experiencing a mild clinical response to B. bigemina following imidocarb treatment and exposure did, in some instances, show a second mild response when challenged 196 days after initial treatment.

Amidines↗
PubMed1986

Genetic aspects of antibody responses in chickens to different classes of antigens.

Six breeding groups of chickens, each characterized by a different haplotype of the B blood group system, were challenged with different classes of antigens, namely Newcastle disease vaccine (ND), infectious bronchitis vaccine (IB), infectious bursal disease viral agent (IBD), Salmonella pullorum antigen (P), and sheep red blood cells (SRBC). Parents were challenged at 20 weeks of age, and their offspring were challenged at 3 weeks of age. Blood samples were taken from the parents at 1 week after challenge, and from the offspring at 1, 2, 3, and 4 weeks after challenge for determination of antibody titers to each antigen. The offspring were also challenged at 8 weeks of age in the wing-web with Rous sarcoma virus (RSV). Tumor scores were taken weekly on individual chickens for the next 10 weeks. There were significant differences (P less than .01) between breeding groups of parents for antibody titer responses to ND, IB, P, and SRBC. There were significant differences (P less than .05) between the breeding groups of offspring for antibody titer responses to ND, IB, IBD, P, and SRBC. There were significant (P less than .01) differences between the breeding groups in the accumulative tumor scores over the 10-week period. The lines that cause regression of Rous sarcomas (R-lines) were significantly (P less than .01) superior in resisting tumor growth to those lines that allow progressive growth of tumors (Pr-lines). The only antigen to which the R-lines gave significantly (P less than .01) higher titers of antibody responses than the Pr-lines was SRBC.

Alleles↗
PubMed1986

Ea-B and Ea-C cellular antigen genes in Leghorn lines resistant and susceptible to acute cecal coccidiosis.

Alloantigen genes B and C of respective loci Ea-B, the major histocompatibility complex (MHC) of chickens, and Ea-C were detected in Leghorn lines R and S selected from common ancestry for resistance and susceptibility to acute cecal coccidiosis, Eimeria tenella (ACC). The lines share genes B2 and C1; R line has B5, Br, and C4, and S line has B1, B3, B4, B6, C2, and C3. Haplotype Br is an apparent recombinant of B2 and B5, possibly F2G2-5. Expression of the F2G2- region of B2 and Br is strong in graft-vs.-host reactions but weak on erythrocytes; in contrast, that of F5G5- of B5 is reduced in graft-vs.-host reactions but strong on erythrocytes. Extinction of B4 in R line and B5 in S line occurred in the last stages of selection, and the frequency of B5 in R line increased as a result of intensification of selection pressure for resistance to coccidiosis. The respective C genes of highest frequency in lines R and S are C1 and C3. The latter is a probable recombinant of C1 and C2. Evidence of roles of the B and C systems in resistance and previous similar evidence for the AE system indicates that genes other than the chicken MHC have measurable effects on infectious diseases.

Alleles↗
PubMed1986

Experimental Babesia equi infection in mature horses.

Nine 4-year-old Arabian geldings were experimentally infected with Babesia equi of European origin. All horses developed detectable parasitemia an average of 30 days after they were inoculated, which was accompanied by a decrease in PCV. The infections were generally mild with no animal deaths. All horses became serologically positive by the indirect fluorescent antibody test within an average of 23 days after they were inoculated and by the complement-fixation test 30 days after they were inoculated.

Animals↗
PubMed1985

Glucose transport across the basal plasma membrane of human placental syncytiotrophoblast.

Transfer of glucose from maternal to fetal circulations requires transport across both the microvillous (maternal-facing) and basal (fetal-facing) plasma membranes of the placental syncytium. We have previously reported transport properties of the microvillous membrane and we now report those of the basal membrane. Basal plasma membrane vesicles were prepared by selective sonication and density gradient centrifugation. Glucose or glucose analogues were rapidly transported across these membranes by facilitated diffusion. Transport was inhibited by cytochalasin B, phloretin and phloridzin. L-Glucose at 1 mM was transferred at only 1/700 of the rate of D-glucose, which indicated an insignificant nonspecific diffusion component. Transport was independent of sodium gradients, and kinetic studies under equilibrium-exchange conditions demonstrated a Km of 23 mM. Competition studies demonstrated that aldohexoses in the C-1 chair conformation were the preferred substrates. Placental steroids estriol and progesterone inhibited transport. In contrast to other polarized epithelia, the basal and microvillous membranes of the human placental syncytium possess transport systems with similar properties. Thus, the directionality and rate of transfer of glucose across the intact syncytium are likely to be direct functions of the materno-fetal concentration gradient and the total transport capacities of the two plasma membranes.

3-O-Methylglucose↗
PubMed1985

Nasal bacterial flora of clinically normal goats.

An enclosed swab assembly was employed to collect nasal mucus from 45 clinically normal goats. Eleven bacterial species were isolated from their nasal cavities. Pasteurella haemolytica and Pasteurella multocida were the most important isolates.

Animals↗
PubMed1984

Malignant melanoma in a goat.

Malignant melanoma was identified in a crossbred goat. It involved the coronary band area and the medial claw of the right hindfoot, which was removed surgically. The goat was reexamined 1 month after tumor removal and found to have widespread metastases with concurrent neurologic signs.

Animals↗
PubMed1984

Ea-A and Ea-E cellular antigen genes in Leghorn lines resistant and susceptible to acute cecal coccidiosis.

The purpose of the work was to explore the diversity and function of alloantigens in chickens differing in genetic resistance to acute cecal coccidiosis, Eimeria tenella (ACC). This paper describes A and E alloantigens, products of linked loci Ea-A and Ea-E, worked out in Leghorn lines R and S, previously selected for respective resistance and susceptibility to ACC. The R line possesses high frequency haplotypes A7E5 and A9E1 with very low frequencies of the recombinants. The S line possesses almost totally different haplotypes ranging from high to low frequency, respectively: A9E3, A9E5, A9E2, and A11E1. Alleles A7 and A11 were differentiated only by fortuitous production of an A reagent in other work on a commercial broiler line, suggesting that alloantigen variability in chickens is a continuum spanning varietal differences. The AE recombinants in both lines remained at very low frequencies for many generations after selection was suspended. Discussion is given for selection having been the most probable force producing nearly unique AE haplotypes in each of the two lines, largely from different cis-trans relations between similar A and E alleles. Thus, interactions of the A and E regions appeared to have been essential to the seeming action of AE on genetic resistance to ACC. The A and E antigens are shown to develop contemporaneously in ontogeny in the earliest generations of embryonic erythrocytes, further suggesting that AE is a coordinated functional complex.

Animals↗
PubMed1984

Development of cell-mediated immunity and resistance to clinical coccidiosis infection in chickens selected for resistance and susceptibility to Eimeria tenella.

The development of cell-mediated immunity (CMI) and resistance to clinical coccidiosis was determined in Auburn Strain Leghorn chickens previously selected for resistance and susceptibility to Eimeria tenella. Auburn Strain Leghorns selected for resistance (R Line) developed CMI and resistance to E. tenella challenge 2 weeks after receiving a commercial coccidiosis vaccine (CocciVac D). In contrast, Auburn Strain Leghorns selected for E. tenella susceptibility (S Line) did not develop significant CMI or resistance to clinical challenge infection until 6 weeks after receiving CocciVac D. The CMI was measured by the ability of chickens to develop a delayed hypersensitivity (DH) skin test response to an Eimeria oocyst antigen extract. Resistance to coccidiosis challenge infection was measured by percent weight gain, lesion scores, fecal scores, mortality, and oocyst output per gram of cecal contents at 7 days after challenge. Our research indicates that there is a strong correlation between innate resistance to coccidiosis and the ability of the chicken to recognize and mount a DH response to the parasite.

Animals↗