Biomedical subjects

J D Olson

Publications and source records attributed to J D Olson.

At least 19 recordsLinked to original sources

PubMed1992

Effect of varying fibrinogen and hematocrit concentrations on magnetic resonance relaxation times of thrombus.

OBJECTIVES: The authors assessed the effects of varying one extracellular component (fibrinogen concentration) and one cellular component (hematocrit) on magnetic resonance (MR) T1 and T2 relaxation times of in vitro blood clots. METHODS: Blood from six male subjects was collected into sodium citrate anticoagulant (3.8%) and the whole blood was separated into platelet-rich plasma and packed erythrocytes. Subsequently, in vitro blood clots were made from varying concentrations of fibrinogen (1, 10, and 100 microM) in Tyrode's solution and washed, packed erythrocytes (hematocrit levels: 0%, 10%, 40%, and 80%). T1 and T2 measurements were completed at 20 MHz within 8 hours of initiating clotting. RESULTS: Significant shortening of MR relaxation times occurred with increasing fibrinogen concentration for hematocrit values of 0% and 10%. Extracellular fibrinogen concentration did not contribute significantly to variation in relaxation times at hematocrit values of 40% and 80%. For any given fibrinogen level, significant shortening occurred in T1 and T2 values for each successive increase in hematocrit values. CONCLUSIONS: Both extracellular (fibrinogen) and cellular (erythrocyte concentration) factors are significant determinants of thrombus T1 and T2 relaxation times.

Adult↗

PubMed1992

Torsion of the gallbladder. A review of four cases.

Four cases of torsion of the gallbladder have been gathered from this area. Three were admitted to our local hospitals and the fourth case occurred in the Veteran's Hospital in Fayetteville. The average age of these four cases was 85, and all patients were very thin. Three patients were female and one was male. One patient died following surgery. This patient had sought help rather late, and died of cardiopulmonary complications. This entity is rare, and only scattered cases are found in the literature. Biliary calculi are found in approximately 50% of the cases. The exact etiology of the torsion is unknown. A redundant mesentery is always present, and kyphosis is frequent. Our patients were all thin. Botha has postulated that vigorous peristalsis in the neighboring viscera or sudden body movement may be responsible. The diagnosis is rarely made preoperatively, but if surgery is not done, death will probably ensue. Later reports have indicated that sonography and abdominal CT scanning might prove helpful in establishing a diagnosis.

Aged↗

PubMed1992

An early case of the Zollinger-Ellison syndrome produced by a carcinoid tumor of the duodenum.

We have reported a case of Zollinger-Ellison Syndrome which proved to be due to a small carcinoid tumor of the wall of the duodenum. At the time that this was found, I could not find any such cases in the literature. In talking with Dr. Ellison personally, it was my impression that he was probably not aware of this syndrome. There are relatively few cases in the literature, and in a report by Dr. Van Heerden, et al from the Mayo Clinic, of 154 patients with carcinoid tumors of the GI tract, there were only two cases of the carcinoid tumor found the duodenum. One had a gastrin producing tumor 1 cm in diameter with positive nodes which was excised locally, and the patient was alive and well and not taking medication after 10 years. In this case, I think that serendipity played a great part, because I had no knowledge of the relation between the carcinoid tumor and the severe ulcer diathesis it produced.

Aged↗

PubMed1991

Transesophageal color Doppler echocardiography of the normal St. Jude Medical mitral valve prosthesis.

Transesophageal color flow Doppler findings are reported in 36 patients with a St. Jude Medical mechanical mitral valve prosthesis who had no auscultatory evidence for prosthetic valve dysfunction. Multiple jets consistent with mitral regurgitation originating from the central and lateral portion of the prosthesis were found in all patients. Maximum jet length ranged from 11 to 51 mm (mean 21 +/- 9 mm). Maximum jet area ranged from 0.2 to 4.1 cm3 (mean 1.2 +/- 0.9 cm2). The color M-mode Doppler interrogation showed two distinct components of the regurgitant jet: brief early systolic flow consistent with valve closure followed by holosystolic regurgitant flow consistent with transvalvular leakage. Four patients (11%) had a maximum regurgitant jet length exceeding 30 mm and absence of early systolic closure regurgitant flow by M-mode color imaging, suggesting clinically silent paravalvular leakage. Two pin-sized paravalvular suture line defects were confirmed in one patient at cardiac transplantation. We conclude that transesophageal echocardiography is a highly sensitive method for detection of mitral regurgitation in the St. Jude Medical mitral prosthesis. Clinically silent paravalvular leakage should be suspected if the maximum jet length exceeds 30 mm and color M-mode interrogation fails to demonstrate an early systolic closure regurgitant flow component.

Echocardiography, Doppler↗

PubMed1991

Transesophageal echocardiography in patients with mechanical circulatory assistance.

Transesophageal echocardiography was used to assess myocardial function and to detect complications after mechanical circulatory support for 8 patients with cardiogenic shock. In 3 of 8 patients, serial transesophageal echocardiography documented improvement of systolic ventricular function, and it was possible to wean these 3 patients from the ventricular assist device. In all patients, transesophageal echocardiography added clinically important information including the extent of left and right ventricular dysfunction (6 patients), presence of atrial or ventricular thrombus (5 patients), presence of pericardial effusion or clot (2 patients), and verification of the position of the intravascular device (1 patient). Thus, transesophageal echocardiography may provide clinically useful information regarding both the underlying cardiac disease and potential complications from the mechanical circulatory assistance.

Adult↗

PubMed1991

Quantitation of DNA hybridization in a silicon sensor-based system: application to PCR.

Rapid, quantitative hybridization assays with good sensitivity are needed in many applications, for example, determining the amount of specific product from PCR. We have developed an assay which relies on the hybridization of a biotinylated oligomer and a fluoresceinated oligomer to a single-stranded target in solution. The hybridized complex is captured by streptavidin to a biotinylated membrane. After capture, the hybridization complex is detected by an antifluorescein-urease conjugate which binds to the fluoresceinated probe. The membrane-bound urease conjugate is exposed to urea and assayed with a pH-sensitive silicon sensor. The total assay time is less than 2 h and the sensitivity limit is 20 x 10(6) molecules with a coefficient of variation, CV, of less than 10%. The assay was applied to the analysis of a model target using PCR. We were able to measure the amount of specific product and the amplification factor during the exponential phase of PCR. Using extrapolation from the measured amounts of amplified product, the initial amounts of target molecules were calculated to be 1.2 x 10(6) and 4.0 x 10(2) when the added quantities were 3 x 10(6) and 3 x 10(3), as determined by serial dilution.

Biotin↗

PubMed1991

Magnetic resonance characterization of blood coagulation in vitro. Effect of platelet depletion.

To optimize magnetic resonance (MR) methods of characterizing thrombi, further studies of biologic determinants of spinlattice (T1) and spin-spin (T2) relaxation times of thrombi are needed. As a step toward evaluating the influence of thrombus cellular composition on MR properties, the authors evaluated the effect of platelet depletion on MR relaxation times of in vitro blood clots. Blood from 13 fasting normal men was collected into sodium citrate (3.8%) and centrifuged ( [10,000 X g] X 5-10 minutes). Platelet-poor specimens (less than 20,000 per mm3) were reconstituted from the plasma and packed erythrocytes to match precentrifugation hematocrit levels. T1 and T2 measurements were made at 20 MHz within three to six hours of initiating clotting. The mean T1 value for platelet-rich (normal) specimens was 1117 +/- 86 mseconds versus 1119 +/- 68 mseconds for the platelet-poor specimens (P greater than .90). The mean T2 value for platelet-rich (normal) specimens was 616 +/- 130 mseconds versus 434 +/- 79 mseconds for the platelet-poor specimens (P less than .001). The mean water content in the platelet-rich (normal) specimens was 79.5% +/- 1.2% versus 80.0% +/- 1.2% in the platelet-poor specimens (P greater than .50). In summary, platelet depletion by buffy coat removal significantly shortens MR T2 values of in vitro clot. These data suggest that thrombus cellular composition, other than erythrocytes, alters MR relaxation times of clotted blood.

Adult↗

PubMed1991

Value of transesophageal echocardiography as an adjunct to transthoracic echocardiography in evaluation of native and prosthetic valve endocarditis.

To determine if transesophageal echocardiography provides better visualization of valvular vegetations than transthoracic echocardiography, we used both methods to evaluate 24 consecutive patients (mean age, 54 years; 15 female patients and nine male patients) referred for symptoms suggestive of infectious endocarditis. Ten of the 24 patients had one or more valvular prostheses. Echocardiograms were classified as positive or negative based on visualization of valvular vegetations or abscesses. Of ten patients with a final diagnosis of infectious endocarditis on extended follow-up, transthoracic echocardiography was positive in five patients. Transesophageal echocardiography not only yielded abnormal findings in all ten of these patients, but also revealed additional information in four of the five patients with abnormal transthoracic echocardiographic examinations. Among the 14 patients who, on subsequent follow-up, were found not to have infectious endocarditis, transthoracic echocardiography was normal in 13 and falsely abnormal in one. Transesophageal echocardiography revealed no evidence of infectious endocarditis in any of these patients. The ten patients who were determined to have infectious endocarditis all had positive blood cultures and no alternative cause for their clinical presentation; in seven patients in this group who underwent operative or postmortem evaluation, infectious endocarditis was confirmed. All patients without infectious endocarditis were demonstrated to have other causes for their clinical presentation. We conclude that transesophageal echocardiography is a highly valuable test in the work-up of patients with suspected infectious endocarditis, especially those patients with inconclusive or normal transthoracic echocardiograms. In addition, transesophageal echocardiography may be of benefit to patients with previously documented infectious endocarditis and a complicated clinical course in whom additional cardiac lesions are suspected but not demonstrated by transthoracic echocardiography.

Abscess↗

PubMed1991

Effects of recombinant methionyl bovine somatotropin (sometribove) in high producing cows milked three times daily.

Effects of daily sometribove administration on milk yield and composition, body condition score, BW, and SCC were evaluated in Holstein cows milked three times daily. Lactating cows (n =104) were assigned randomly to control or sometribove-treated (25 mg/d) groups. The experimental period was 16 wk, consisting of 2-wk pretreatment, 12-wk treatment, and 2-wk posttreatment periods. All cows were injected once daily starting at 53 to 180 d postpartum, housed in free stalls, and fed one of five total mixed rations according to milk production. Body weights were measured weekly, and body condition was scored biweekly. Milk yield was recorded daily, and weekly milk samples were analyzed for fat, protein, lactose, total solids, and SCC. Milk yield and milk protein were increased 18.8% (38.6 vs. 32.5 kg/d) and 3.3% (3.1 vs. 3.0%), respectively, whereas percentage of milk fat, lactose, SNF, SCC, and BW were unaffected by treatment. Overall average body condition scores were lower for the sometribove-treated group versus control (2.2 vs. 2.4). No apparent differences in the number of cows treated for mastitis, foot rot, displaced abomasum, or lameness were observed between treatment groups. Sometribove treatment significantly enhanced milk yield (6.1 kg/d) with no apparent negative effects on health in high producing cows milked three times per day.

Animals↗

PubMed1991

Responses by lactating cows in commercial dairy herds to recombinant bovine somatotropin.

Cows (890) in 15 US herds were assigned randomly in equal numbers to control or bST injections (500 mg in a prolonged-release form every 14 d for 12 wk) within three stages of lactation (57 to 100, 101 to 140, and 141 to 189 d postpartum) and two parity groups (primiparous and multiparous). Yield and milk composition were monitored 1 d/wk for 16 wk including 2 wk pretreatment and 2 wk posttreatment. Increases in milk and FCM due to bST injections were less at 57 to 100 d than at 101 to 189 d postpartum (milk 3.6 vs. 5.5; FCM 3.9 vs. 6.1 kg/d per cow), and increases in milk and FCM were more for multiparous than for primiparous cows (milk 5.5 vs. 4.2; FCM 6.0 vs. 4.7 kg/d cow). Temporarily, concentration of milk fat increased and protein decreased; later, concentrations for control and injected cows were similar. Postinjection milk fat concentration decreased, but milk protein concentration increased temporarily. The net increase in milk (and FCM) varied significantly among herds from 2.9 to 7.6 kg/d per cow (mean, 4.9 kg). Responses in FCM were similar over a wide range of pretreatment yields. A great variety of feed ingredients were fed as total mixed rations, and nutrient concentrations varied greatly. The SCC were similar before, during, and after treatment, but increase in FCM of injected cows exhibited a negative correlation with pretreatment SCC. Changes in body condition score of sometribove-injected cows varied among herds (.25 to -.45) and averaged -.02 compared with .07 for controls. There was no pattern in incidence of mastitis during sometribove injections.

Animal Feed↗

PubMed1991

Screening of anionic salts for palatability, effects on acid-base status, and urinary calcium excretion in dairy cows.

Six anionic salts [MgCl2.6H2O, MgSO4.7H2O, CaCl2.2H2O, CaSO4.2H2O, NH4Cl, and (NH4)2SO4] were evaluated for their effects on dietary DM intake, systemic acid-base balance, and urinary excretion of Ca. Each of the six salts was fed to 12 nonlactating, nonpregnant Holstein cows for 1-wk periods in two replicates of a 6 x 6 Latin square design. All salts were fed at the rate of two equivalents cow-1 d-1. Anionic salt treatments did not decrease DM intake compared with the control diet fed without salts. Blood pH was not affected by any of the salt treatments; however, mild, compensated metabolic acidosis was evidenced by decreased blood bicarbonate concentrations and decreased blood base excess when any of the salts was fed. Urinary pH and urinary base excess also were lowered by all of the salts. Fractional excretion of urinary Ca was increased by all salt treatments. All six anionic salts tested were of similar value in their acidifying effects and in their ability to increase urinary excretion of Ca.

Acid-Base Equilibrium↗

PubMed1990

Isolation and characterization of an acquired antithrombin antibody.

A 68-year-old man, following mitral valve replacement, presented with a low-grade chronic consumptive coagulopathy. Laboratory analysis showed mild fibrinolysis, minimal effect of coumadin therapy, and a prolonged thrombin time (greater than 150 seconds using bovine IIa). When purified human IIa was used the thrombin time normalized to within 17 seconds of controls, suggesting a possible inhibitor of bovine IIa. An anti-IIa antibody was isolated by protein A-Sepharose (Sigma, St Louis, MO) chromatography followed by affinity chromatography using a bovine IIa-Sepharose column. The effects of this purified anti-IIa antibody on both bovine and human IIa procoagulant and anticoagulant functions were studied. The isolated immunoglobulin G (IgG) was observed to inhibit bovine IIa in all assays tested. This IgG was also able to slightly prolong fibrinogen clotting by human IIa. Using an enzyme-linked immunosorbent assay it was observed that the IgG bound to bovine IIa, bovine II, human IIa, but not to human II. Further, binding was detectable at approximately 50-fold lower concentrations to bovine IIa (1 nmol/L IgG concentration) than to human IIa (50 nmol/L IgG concentration). The effect of the antibody on the reaction between IIa and AT III/heparin was investigated. Human IIa was found to be protected from AT III/heparin neutralization in the presence of this antibody. These results suggest that this patient developed an antibody that strongly binds to and inhibits the bovine IIa in all assays tested. However, the antibody only significantly affects human IIa neutralization by AT III/heparin, and has little effect on the human IIa procoagulant activity. These data suggest that the decreased effect of AT III/heparin on this patient's IIa may have been a contributing factor in his coagulopathy. The exact cause of this antibody development is unclear, but the role of bovine topical thrombin used during cardiac valve replacement surgery is suspect.

Aged↗

PubMed1990

A silicon sensor-based filtration immunoassay using biotin-mediated capture.

A sensitive sandwich immunoassay for human chorionic gonadotropin (hCG) was developed with biotin-mediated filtration capture and silicon sensor detection. A high density of biotin on the membrane assured efficient capture of complexes containing streptavidin and analyte. Capture efficiency was not affected over a wide range of filtration flow rates or biotin concentrations. The assay utilized the pH sensing ability of the light addressable potentiometric sensor (LAPS) for the detection of urease-antibody conjugates. A LAPS reader was constructed which allowed the enzyme conjugate to be detected in approximately 1 microliter volumes. Effects from variations in detection volume were studied. 10 pg of hCG could be detected in an assay time of 20 min with four standard deviations separation from background. Comparison to a commercial RIA was made.

Antibodies, Monoclonal↗

PubMed1990

Effects of androgenizing dairy heifers with ear implants containing testosterone and estrogen on detection of estrus.

Lactating dairy cows in four lots were observed for sexual behavior for 6 mo. One freemartin heifer in each lot was implanted with testosterone propionate and estradiol benzoate to aid in detection of estrus. Blood samples were obtained from androgenized heifers every other week for determination of serum testosterone. The addition of an androgenized heifer to each lot increased the number of mounts and attempts to mount cows, both overall and within observation periods. Thus, the likelihood of detecting a cow in estrus was increased with the addition of the androgenized heifers. Greatest benefit was seen when one or two cows were simultaneously in estrus in each lot. Observational data and serum progesterone concentration of mounted cows indicated that androgenized heifers were selectively mounting open cows displaying estrus, whereas the remaining nonandrogenized cows were less selective with their mounting activity. Serum testosterone increased after heifers were implanted, but testosterone was not related to the proportion of sexual activity. Duration of sexual activity by the implanted heifers was approximately 90 d.

Animals↗

PubMed1990

Pulsed Doppler umbilical artery waveforms: significance of elevated umbilical artery systolic/diastolic ratios in the normally grown fetus.

Previous studies have demonstrated a high correlation between elevated resistance in the placental circulation, evidenced by abnormal umbilical artery systolic-to-diastolic (S/D) ratios, and the subsequent birth of a small for gestational age (SGA) infant. However, few data exist on the significance of elevated S/D ratios for pregnancies in which outcome does not involve an SGA infant. Pulsed Doppler spectral recordings and level II ultrasound examinations were performed 373 times in 256 referred high-risk patients. Doppler data were not used for patient management decisions. Thirty-two women with elevated umbilical artery S/D ratios of 4.5 or greater (defined as abnormal regardless of gestational age) gave birth to non-SGA infants. The ultrasound characteristics and outcome for this group were compared with those of 200 patients who were also non-SGA but who exhibited normal waveforms and with 24 SGA infants with predominantly abnormal waveforms. Thirty-one percent of the non-SGA infants with abnormal waveforms had structural malformations, a rate significantly higher (P less than or equal to .03) than the 18% malformation rate in the normal-waveform group. Further, the stillbirth rate and number of terminations of pregnancy for lethal anomalies were five times greater in the non-SGA group with abnormal waveforms than in the non-SGA group with normal waveforms (P less than or equal to .001). A wide variety of structural malformations was observed in the abnormal-waveform group, most frequently involving the central nervous system. Amniotic fluid volume tended to be decreased in the SGA group, whereas increased amniotic fluid volume or hydramnios was seen in 23% of the non-SGA abnormal-waveform group.

Amniotic Fluid↗

PubMed1989

The incidence and significance of hemostatic abnormalities in patients with head injuries.

Abnormal coagulation and fibrinolysis is a frequent complication in patients with head injury. This complication can be severe enough to lead to hemorrhage or thrombosis. A study was undertaken to determine if the hemostatic abnormalities are reliable indicators of outcome. Hemostasis in 269 patients with head injuries alone was screened using platelet count (PC), prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin clotting time (TCT), fibrinogen assay (FIB), level of fibrin-fibrinogen degradation products (FDP), and disseminated intravascular coagulation (DIC) score in the first 24 hours after injury. Test results were compared with the outcome (discharged or dead) in the entire group and in subgroups divided on the basis of the severity of injury as determined by the Glasgow coma score (GCS). Increased consumptive coagulopathy at admission, as reflected in the DIC score, predicts the outcome of head-injured patients with a high degree of accuracy. The degree of increase of the initial FDP level and prolongation of TCT also correlated positively with the outcome. Prolongation of the APTT correlated strongly with unfavorable outcome in a large group of patients, and in a small group, markedly accelerated APTT also predicted death. Stepwise logistic regression analysis demonstrated that GCS, FDP level, and DIC score predicted outcome. Other tests did not provide additional predictive value. Abnormal hemostasis frequently complicates the course of patients with head injuries. This study demonstrates that hemostasis tests are predictors of outcome in these patients.

Adolescent↗

PubMed1989

Adhesion of platelets to purified solid-phase von Willebrand factor: effects of wall shear rate, ADP, thrombin, and ristocetin.

When platelets are stimulated with adenosine diphosphate (ADP), thrombin, or ristocetin, they bind soluble von Willebrand factor (vWF). In contrast, platelets adhere to solid-phase vWF without apparent stimulus. This work characterizes the adhesion of washed human platelets to highly purified solid-phase human vWF. VWF (iodine 125-labeled vWF) was demonstrated to bind in a quantifiable fashion to the internal surfaces of glass capillary tubes, saturating at a surface density of 3.0 mg/ml. The multimeric structure of bound vWF was the same as that of normal vWF. Platelets were washed, labeled with indium 111, and resuspended with washed red blood cells (RBCs) in balanced salt solution containing Ca++, Mg++, and apyrase. The washed platelet RBC suspension was aspirated through capillary tubes to which vWF was adsorbed. Adhesion of platelets to adsorbed vWF was directly dependent on the surface density of vWF. Increasing wall shear rate (100 to 5000 sec-1) produced increasing platelet adhesion to maximum reached at 2500 sec-1. Platelets bound to the solid-phase vWF in an irreversible fashion, and, as demonstrated with scanning electron microscopy, they spread on the surface. When used to stimulate the platelets, ADP, thrombin, and ristocetin all increased the platelet adhesion to solid-phase vWF. ADP- and thrombin-stimulated reactions were inhibited by prior treatment of the platelets with 5'-p-fluorosulfonylbenzoyl adenosine. This inhibitor of ADP binding had no effect on the baseline platelet adhesion reaction (without ADP or thrombin). Adenosine in concentration up to 1 mmol/L failed to inhibit adhesion. The data demonstrate that washed platelets adhere to solid-phase vWF without added agonists, that the reaction is dependent on surface density vWF and wall shear rate, that they bind irreversibly, and that they demonstrate surface spreading. In addition, these platelets can be stimulated to increase their adherence to vWF by using ADP, thrombin, and ristocetin.

Adenosine Diphosphate↗

PubMed1988

A rapid assay for von Willebrand factor.

Multiple assays have been described which quantify von Willebrand Factor (vWF) in plasma or other specimens. An assay using a modification of the microtitre method(1) is described. Washed platelets fixed in formalin and frozen in dimethylsulfoxide are substrate for the reaction. Platelets, ristocetin and the specimen to be assayed are combined in the wells of a microtitre plate. The reaction is mixed for defined times and agglutination of platelets read visually. By adjusting the concentration of platelets, concentration of ristocetin and time, the sensitivity can be adjusted over a wide range.

Humans↗