Engineered humanized dimeric forms of IgG are more effective antibodies.

Humanized IgG1 M195 (HuG1-M195), a complementarity determining region-grafted recombinant monoclonal antibody, is reactive with CD33, an antigen expressed on myelogenous leukemia cells. M195 is in use in trials for the therapy of acute myelogenous leukemia. Since biological activity of IgG may depend, in part, on multimeric Fab and Fc clustering, homodimeric forms of HuG1-M195 were constructed by introducing a mutation in the gamma 1 chain CH3 region gene to change a serine to a cysteine, allowing interchain disulfide bond formation at the COOH terminal of the IgG. Despite similar avidity, the homodimeric IgG showed a dramatic improvement in the ability to internalize and retain radioisotope in target leukemia cells. Moreover, homodimers were 100-fold more potent at complement-mediated leukemia cell killing and antibody-dependent cellular cytotoxicity using human effectors. Therefore, genetically engineered multimeric constructs of IgG may have advantages relative to those forms that are found naturally.

Characterization of immunotoxins active against ovarian cancer cell lines.

The purpose of the present study was to develop immunotoxins directed against human ovarian carcinoma cells. Four monoclonal antibodies (260F9, 454C11, 280D11, and 245E7) were chosen because they were found to bind to various ovarian carcinoma cell lines. These antibodies were covalently linked to either Pseudomonas exotoxin (PE) or ricin A chain (RTA), and the conjugates were tested against five ovarian cancer cell lines (OVCAR-2, -3, -4, -5; A1847). The ability of the immunotoxins to inhibit both protein synthesis and colony formation was evaluated. Qualitatively similar results were obtained for both types of assays. Usually, PE conjugates were more toxic than their corresponding RTA conjugates. 454C11-PE was very toxic for all ovarian carcinoma lines, whereas 454C11-RTA had low activity. Both 260F9-PE and 260F9-RTA were active in all OVCAR cell lines but not in A1847 cells. 280D11-PE was toxic for OVCAR-4; otherwise, 280D11-PE and RTA conjugates of both 280D11 and 245E7 had little activity. Specificity of immunotoxin action was shown by competition by excess antibody, nontoxicity in nontarget cells, and inactivity of an irrelevant immunotoxin. To investigate the basis of antibody-dependent differences in activity of the various immunotoxins, antibody uptake was studied in OVCAR-2 cells, and the results indicate that antibody internalization is one important factor in the activity of immunotoxins.

Cures and partial regression of murine and human tumors by recombinant human tumor necrosis factor.

We tested the effect of recombinant human tumor necrosis factor (TNF) on the growth of the murine methylcholanthrene induced fibrosarcoma and the human ovarian carcinoma (NIH:OVCAR-3) in mice. The mice received multiple doses (25-250 micrograms/kg) of TNF starting 7-10 days after s.c. transplantation of tumors when they were easily palpable. TNF was administered i.v. every other day for a total of 6 injections per mouse, or i.p. daily for 7 days. Complete tumor regression was observed in the methylcholanthrene induced tumor bearing mice in 90% of the mice treated with TNF (100 micrograms/kg), 67% treated with TNF (50 micrograms/kg), and 34% treated with TNF (25 micrograms/kg). Tumors which did not completely regress were growth retarded during the course of TNF treatment. All mice given the highest TNF dose are still alive and tumor free (currently over 400 days), whereas the median survival of control mice was 28-39 days. Partial regression was observed in 100% of mice bearing the ovarian carcinoma treated i.p. with 250 micrograms/kg. Injections of TNF i.v. resulted in higher percentage of cures than i.p. injections at similar dose levels. These results suggest that tumor necrosis factor represents a likely potent drug against solid tumors and that the method of administration is critical in optimizing its use in cancer.

Body size, composition, and fitness in adolescents with elevated blood pressures.

Increased body size is often found in children with elevated blood pressures, but it is not clear whether this is a result of obesity or early maturity. Similarly, levels of activity and fitness have marked effects on blood pressure and body composition. To study these interrelated factors, we measured height, weight, and body composition (skinfold thickness and total body water) as well as heart rate, blood pressure, and oxygen consumption at rest and during exercise in 192 ninth grade boys and girls, 102 with persistently elevated blood pressures at or above the 95th percentile and 90 matched controls with blood pressures below the 50th percentile for the entire population of 10,641 Dallas County ninth graders tested. Differences in resting blood pressures also were present during maximal exercise and recovery periods. Boys with persistently elevated blood pressures were characterized by increased supine and recovery heart rates, normal fitness, excess size for age in the absence of obesity, and early maturation. Girls with persistently elevated blood pressures had increased heart rates, decreased fitness, and obesity.

Effects of clonidine on 24-hour hormonal secretory patterns, cardiovascular hemodynamics, and central nervous function in hypertensive adolescents.

To assess the potential of antihypertensive drugs for interference with somatic growth and sexual development in hypertensive children, the effect of clonidine therapy on various endocrine, cardiovascular, and neuromuscular functions has been examined in five male adolescents with idiopathic hypertension. In studies done before and at the end of 4 weeks of twice-daily clonidine therapy, in an average daily dose of 0.31 mg, no significant effects were noted in the secretory patterns of growth hormone, luteinizing hormone, follicle-stimulating hormone, prolactin, cortisol, aldosterone, or testosterone, measured in blood obtained every 20 minutes for 24 hours. In blood obtained while the patients were supine and then erect, plasma renin activity and norepinephrine levels were significantly lowered after clonidine therapy. Cardiovascular responses to dynamic exercise were little altered beyond a 17% decrease in maximal oxygen consumption. The performance of fine motor skills was minimally altered. These data provide preliminary evidence that clonidine, an antihypertensive drug that affects the adrenergic nervous system, may not interfere with normal growth and maturation in adolescent males.

Validity of mass blood pressure screening in children.

The validity of a mass blood pressure screening program carried out on Dallas high school students who were followed for at least 3 years is reported. Blood pressure results on initial screening in the tenth grade were related to outcome blood pressure status. The frequency of initial blood pressure elevation (systolic and/or diastolic pressure above the 95th percentile) was 10%, whereas the prevalence of sustained elevation in the tenth grade was less than 2%. The initial screening correctly identified 72% of those who had sustained elevations on all three tenth grade examinations (sensitivity), and correctly identified 91% of those who did not have sustained elevations (specificity). However, the predictive value of an initial positive screening result was low, at only 17% (152/900). The high proportion of false-positive results represents a significant cost to any blood pressure screening program, both in economic terms and in its potential for creating anxiety among families with children having only transiently elevated blood pressure. Because the costs are high and the yield from mass screening of children low, case finding of childhood hypertension should remain the responsibility of the physician who sees children in the clinical setting.

Left ventricular hypertrophy in adolescents with elevated blood pressure: assessment by chest roentgenography, electrocardiography, and echocardiography.

The purpose of this study was to assess the prevalence of left ventricular hypertrophy in adolescents with persistently elevated blood pressures. Chest roentgenograms, electrocardiograms, and echocardiograms were performed on 50 adolescents with elevated blood pressure and 50 matched normotensive control subjects. No subject in either group demonstrated cardiomegaly on x-ray. Interpretation of the electrocardiograms indicated that similar numbers of both hypertensive (7/50) and control subjects (8/50) had ECG evidence of left ventricular hypertrophy. The echocardiograms showed that the mean left ventricular wall thickness (LVWT) in the hypertensive adolescents was 7.8 mm +/- 0.1 (SE), compared with 6.5 +/- 0.1 in the control subjects (P less than .001). When the measurements were indexed to body surface area, the difference remained highly significant. Indexed left ventricular mass (LVM)/body surface area (BSA) was also significantly greater (P less than .001) in the hypertensive (84.2 gm/sq m +/- 2.1) than in the control subjects (72.0 +/- 2.1). Using data from the normotensive control subjects, we defined the 95th percentile for both LVWT/BSA and LVM/BSA. Among hypertensive adolescents, 9/50 had LVWT/BSA and 8/50 had LVM/BSA above this level. For control subjects, only 1/50 had elevated LVWT/BSA values and 2/50 elevated LVM/BSA values. This study demonstrates that hypertensive adolescents have an increased prevalence of left ventricular hypertrophy and that echocardiography is the most useful noninvasive method to detect these changes.

Usefulness of exercise stress testing for prediction of blood pressure trends.

The purpose of this study was to determine whether values of blood pressure during exercise help predict which adolescents are prone to maintain high blood pressure. Dynamic and isometric exercise stress tests were performed on 131 adolescents who had had systolic or diastolic pressures greater than the 95th percentile on three examinations the previous year. Follow-up blood pressures were measured 1 year after the stress testing, and outcomes were classified on the basis of the blood pressure status that year. Stepwise regression analysis was used to examine the association between earlier blood pressures and exercise pressures with outcome pressures. In both male and female adolescents, the average resting systolic pressure on the earlier survey was the best predictor of systolic pressure 2 years later. Blood pressures and heart rates during dynamic and isometric exercise did not significantly contribute to the models' prediction of future systolic or diastolic pressures. The data suggest that exercise stress testing is not a valid method for predicting youths whose blood pressures will remain elevated over the next 1 to 2 years.

The frequency of pericardial effusions in bacterial meningitis.

Because of our experience with four cases of purulent pericarditis complicating bacterial meningitis during a 13-month period, we performed a prospective study to determine the frequency of this complication. Echocardiograms were done on 100 patients with bacterial meningitis. Small or moderate pericardial effusions were detected in 19 patients, but none had symptoms or signs related to the effusion. Pericardiocentesis was done in one infant; all the other effusions resolved spontaneously. Patients with effusion were significantly younger than those without this complication, but no other significant risk factors were identified. A literature survey indicated that symptomatic pericarditis occurs in fewer than 1% of patients with meningitis. Conversely, in series of cases of purulent pericarditis, associated meningitis was reported in 12% of patients. We concluded that pericardial infection is common in patients with meningitis but that it is usually of no clinical significance and resolves with antibiotic therapy.

Response of hypertensive adolescents to dynamic and isometric exercise stress.

Isometric handgrip and dynamic exercise stress tests were performed on 109 hypertensive and 74 normotensive subjects 14 to 17 years old. The hypertensive subjects had resting systolic or diastolic pressures persistently above the 95th percentile on four consecutive examinations. Blood pressures and ECGs were recorded during isometric handgrip (25% maximum effort for four minutes) and bicycle ergometry until the subject was exhausted. The hypertensive subjects increased systolic pressure by an average 16 mm Hg with isometric exercise and 53 mm Hg with dynamic exercise. Control subjects had similar pressure changes, averaging 18 and 54 mm Hg, respectively. During isometric handgrip stress, diastolic pressures increased 12 mm Hg in hypertensive subjects and 18 mm Hg in control subjects. Only two hypertensive adolescents developed systolic pressures exceeding 200 mm Hg during dynamic exercise stress, and none developed systolic pressures above 200 mm Hg during isometric exercise stress. None of the normotensive or hypertensive subjects developed cardiac arrhythmias and the prevalence of ST segment depression during maximal stress was less than 2% in both groups. Therefore, in adolescents with mild to moderate hypertension the risk of developing significant ECG or hemodynamic abnormalities during mild isometric or heavy dynamic exercise is small. We believe the decision to restrict physical activity of an adolescent with elevated pressures should be based on the development of abnormal ST segment depression, cardiac arrhythmias, or excessive blood pressures at the time of exercise stress testing.

Hypertension screening in schools: results of the Dallas study.

The purpose of this study was to determine the prevalence of persistent blood pressure elevations in an eighth-grade population composed of three ethnic groups, and to determine the feasibility of using school health facilities for hypertension screening. Blood pressure was recorded in 10,641 subjects (90% of the total eighth-grade population) in the Dallas Independent School District. Blacks made up 46% of the population; non-Latin whites, 40.1%; and Latin-Americans, 13.9%. On the first blood pressure screening, 8.9% had systolic or diastolic pressures or both at or above the 95th percentile. Of those whose blood pressures were elevated on the first examination, 98.3% were reexamined. After the third examination, 1.2% continued to have systolic hypertension, and 0.37% diastolic hypertension. No student had diastolic pressure above 90 mm Hg on all three examinations. The prevalence of persistent hypertension was similar for the three ethnic groups. Analysis of variation in blood pressure measurements revealed that the school nurses introduced a relatively small increase in variability. These data indicate that although school screening initially identifies large numbers of students as having inconstant pressure elevations, subsequent follow-up examinations show that less than 2% have persistent hypertension.

Fatal Haemophilus influenzae endocarditis diagnosed by echocardiography in an infant.

A 1-year-old boy was admitted to the hospital with Haemophilus influenzae meningitis. On the second hospital day a heart murmur heard on admission seemed louder. No signs of congestive heart failure were present. An echocardiogram demonstrated a persistent echo-dense mass behind the anterior leaflet of the mitral valve. A presumptive diagnosis of endocarditis was made. After ten days of antibiotic treatment the child was considerably improved. Treatment was continued for endocarditis. Over the next several days the infant's condition deteriorated. On the 16th hospital day he died. Autopsy examination showed a large vegetation attached to the posterior mitral valve leaflet. Bacterial endocarditis caused by H influenzae is uncommon at any age and rare in children. Echocardiography provided a definitive diagnosis early in the hospital course of this patient.

A model system to demonstrate the role of cavitational activity in ultrasonic scaling.

A model system consisting of vacuum-deposited aluminum on glass was developed to demonstrate the effectiveness of cavitational activity (occurring within the cooling water supply of a dental ultrasonic scaler) in the removal of particulate material from solid surfaces. The amount of solid material removed from the model system by this cavitational activity was quantified by a spectrophotometric technique. It was shown that cavitational activity occurring within the cooling water is an important contributory factor in the cleaning efficacy of the ultrasonic scaler operated under conditions similar to those employed clinically.

Metabolism and pharmacokinetics of deuterium-labelled di-2-(ethylhexyl) adipate (DEHA) in humans.

The metabolism and pharmacokinetics of [2H10]di-2-(ethylhexyl) adipate (DEHA) labelled on the ethyl side-chains was determined in six male volunteers. The dose administered was 46 mg [2H10]DEHA given orally. No parent molecule was found in plasma; however, the metabolite [2H5]2-ethylhexanoic acid (EHA) was detected (mean rate of formation: 1.63 +/- 1.19/hr; mean rate of elimination: 0.42 +/- 0.1/hr). Further oxidative metabolism products were detected in urine; the dominant metabolite identified was EHA present as a conjugate and accounted for an average of 8.6% of the administered dose. [2H5]2-Ethyl-5-hydroxyhexanoic acid, [2H5]2-ethylhexanedioic acid, [2H5]2-ethyl-5-keto-hexanoic acid and [2H5]2-ethylhexanol together accounted for a further 3.5% of the dose. The fate of the remainder was not determined.

Ultrasound in dentistry. Part 1--Biophysical interactions.

Ultrasound has many applications in the field of dentistry. However, it is only recently that the applications and effects of its physical properties have been rationalized and understood. Ultrasound may be generated by either magnetostriction or piezoelectricity, although the former is more commonly used in dental applications. Interactions of ultrasound with biological tissues may be caused by either thermal or mechanical mechanisms. The mechanical forces produced may be a result of cavitation, acoustic microstreaming and radiation pressure forces. An understanding of these interactions allows a more knowledgeable appreciation of the effectiveness, safety limitations and rationale of dental ultrasonic instrumentation.

Ultrasound in dentistry. Part 2--Periodontology and endodontics.

Ultrasound in the kHz frequency range is used widely in clinical dentistry. The most common uses are in the fields of periodontology and endodontics. The ultrasonic scaler works by the vibratory chipping action of the oscillating tip and is assisted by the presence of cavitational activity in the associated cooling water. When assessing clinical studies it is often difficult to interpret results from different workers due to the lack of standardization of the ultrasonic scaler. Operators should be aware of the oscillatory pattern of different instruments. Endosonics utilizes an ultrasonically oscillating endodontic file to clean and shape the root canal prior to obturation. The cleaning ability of such files is assisted by the occurrence of acoustic microstreaming forces. The endosonic file is prone to constraint when it contacts the canal wall which alters its oscillatory pattern. Clinical techniques should be modified to reduce this problem.

The development of criteria for the assessment of complete dentures.

Criteria for the assessment of complete dentures have been published by several groups of workers but none have proved universally reliable. The present study was undertaken in an attempt to develop criteria of proven reliability for the assessment of the occlusion, articulation, retention, stability and appearance of complete dentures and the health of their supporting tissues. The criteria formulated were subjected to a series of evaluations of their reliability followed by attempts at refinement where this was unsatisfactory. Although levels of agreement between independent assessments made using the criteria improved as the study progressed, an acceptable level of reliability was not attained. The possible reasons for this are discussed.

Problems in the assessment of complete dentures.

The evidence for the reliability of some of the most widely used criteria for the assessment of complete dentures is reviewed and a number of factors discussed which might account for the contradictory nature of this evidence, including methods of statistical analysis, the wording of criteria and possible extraneous influences on the judgment of observers using the criteria. Adequate and consistent reliability has not been demonstrated for any of the criteria which have been proposed and the development of either more reliable criteria or of objective tests of the performance of complete dentures is a priority if the results of epidemiological surveys of complete dentures are to be regarded as meaningful.

Oral pharmacokinetics of fluazifop-butyl in human volunteers.

1. Fluazifop-butyl, the active ingredient of FUSILADE, a selective herbicide, was administered orally to three male volunteers at a dose level of 0.07 mg kg-1 body weight. Over a period of 6 d between 80 and 93% of the dose was excreted in urine as the metabolite fluazifop, the majority within the first 24 h. Peak plasma concentrations of fluazifop occurred 1-2.5 h after administration. 2. The elimination of fluazifop from plasma and urine can be described by a one-compartment pharmacokinetic model and the elimination half-life was estimated from blood and urine data to be within the range 9-37 h. Fluazifop was found to bind to serum proteins. 3. The study indicates that the amount of fluazifop-butyl absorbed in exposed persons can be assessed by measuring fluazifop concentrations in urine.

Organophosphate nerve agent detection with europium complexes.

We explore the detection of paraoxon, a model compound for nonvolatile organophosphate nerve agents such as VX. The detection utilizes europium complexes with 1,10 phenanthroline and thenoyltrifluoroacetone as sensitizing ligands. Both europium luminescence quenching and luminescence enhancement modalities are involved in the detection, which is simple, rapid, and sensitive. It is adaptable as well to the more volatile fluorophosphate nerve agents. It involves nothing more than visual luminescence observation under sample illumination by an ordinary hand-held ultraviolet lamp.