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PubMed1988

Additivity, subadditivity, and the use of visual information: a reply to Massaro (1988).

Previously we (Bruno & Cutting, 1988) explored the perception of spatial relations among objects laid out in a computer-generated environment. In his commentary on our article, Massaro (1988) raised several issues. The most important is from his reanalysis, which indicated that--because of a subadditive trend in the results--additive and multiplicative strategies fit our data in Experiment 1 about equally well. In reply, we performed a different analysis. Results corroborate subadditivity--and hence multiplicative information combination--in Experiment 1 but provide no evidence for it in Experiments 2 and 3. On the whole, then, the results still support additivity more strongly than any other combination rule and thus support our notion of minimodularity.

Depth Perception↗
PubMed1985

Absence of respiratory effects in subjects exposed to low concentrations of TDI and MDI: a reevaluation.

Because of criticisms of the authors' previously reported study showing absence of respiratory effects in subjects exposed to low concentrations of toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI), the data have been reanalyzed. This reanalysis confirms the accuracy of the results and the conclusions based on them. Subjects exposed to 0.0010 to 0.0015 ppm of TDI and around 0.0003 to 0.0006 ppm of MDI demonstrated a normal age- and smoking-related rate of decline in forced expiratory volume in 1 s and no evidence that it was related to isocyanate exposures. Control of isocyanate exposure sufficient to protect industrial workers against measurable deterioration in lung function appears feasible.

Cyanates↗
PubMed1986

Immunodeficiency in rhesus monkeys associated with the original Mason-Pfizer monkey virus.

The Mason-Pfizer monkey virus (MPMV) was reisolated from a cryopreserved sample of the original MPMV-containing rhesus breast carcinoma, and complete integrated MPMV provirus was detected in chromosomal DNA of this tumor. Reanalysis of the in vivo pathogenicity and molecular character of MPMV reisolated from the rhesus breast tumor and analysis of the original MPMV after long-term in vitro propagation in human and rhesus cells show that the original MPMV produces an acquired immunodeficiency similar to that caused by the recently described simian acquired immune deficiency syndrome type D retroviruses, and the MPMV genome and its immunosuppressive effect in vivo have remained stable despite prolonged in vitro passage in human and rhesus cells.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Nursing in a service line organization.

Thoreau has said that change's sake is not progress. Clarity of purpose and desired outcomes; the provision of sufficient time to educate and ensure cooperation; refocusing and reanalysis; support for staff in leadership positions; and high visibility throughout the organization on the part of top level management are mandatory in bringing about a radical change such as our organization has experienced. The Alta Bates-Herrick Hospital has a rich tradition of high quality care in Berkeley and, indeed, throughout Northern California. The founders of both campuses, Alta Bates, RN, and Leroy Herrick, MD, established a heritage of concern, compassion, and caring. Streamlining the structure of the hospital to ensure fiscal viability, efficiency, and the ability to respond quickly to challenges coupled with the ongoing internal efforts to articulate and retain high quality care will continue to serve the people of our community well.

California↗
PubMed1988

Enzyme polymorphism of the malaria vector, An. balabacensis (Diptera: Culicidae) revisited--why sample natural populations?

Two separate observations from recent electrophoretic studies of the systematics and population genetics of laboratory-reared populations which had a long history of colonization in various laboratories, were found to be inconsistent with the present study which used wild-caught populations from East Malaysia. Reanalysis of the two data sets generally indicated a low amount of genetic variation in laboratory colonies. The latter is characterized by higher frequency of monomorphic loci, low average heterozygosity values and, in one extreme case, no variability at two loci. However, natural populations of An. balabacensis and An. leucosphyrus showed more protein variability by the use of polyacrylamide gel electrophoresis. Since laboratory-maintained mosquitoes are genetically and phenotypically different from those in the field, results of laboratory studies on the systematics and population genetics of Anopheles species complexes may be biased.

Animals↗
PubMed1988

The diagnostic dilemmas of hyperthyroxinemia and hypothyroxinemia.

It should be apparent that the diagnosis of thyrotoxicosis and hypothyroidism can be correctly made in the majority of ambulatory patients. However, the clinician needs to be extremely careful in reaching such a definitive diagnosis on the hospitalized patient. Both the clinical features and the standard thyroid function tests need careful evaluation and reanalysis before the diagnosis of thyroid dysfunction can be made with confidence.

Humans↗
PubMed1988

Testing for linear trends in proportions using correlated otolaryngology or ophthalmology data.

This paper is concerned with the issue of testing for trend with correlated binary data. We consider the problem where one has either one or two ears (or eyes) available for analysis at baseline and one wishes to look at changes over time in a dichotomous outcome taking into account the correlation between responses from two ears. A reparameterization of Rosner's (1982, Biometrics 38, 105-114) correlated binary data model is presented and applied to a test for trend where the stratifying variable is age (or any other subject-specific variable). Observed and expected values are calculated for the trend statistic separately for both unilateral and bilateral cases and are then summed to obtain an overall summary statistic. The proposed method is illustrated by a reanalysis of data presented in a published study of the efficacy of antibiotics for the treatment of otitis media.

Amoxicillin↗
PubMed1988

Hepatic arterial and portal venous components of liver blood flow: a dynamic scintigraphic study.

Assessment of liver hemodynamics can be obtained by analysis of first pass flow studies through the liver and spleen using 99mTc compounds which are not actually trapped by these organs. This study examines new and existing methods for determining the relevant contribution made by the hepatic artery and portal vein to total liver blood flow, from these first pass studies. Eighty-two studies were performed in 56 patients with both normal and abnormal liver function. Using region of interest analysis, time-activity curves were obtained for the lungs, liver, spleen, and left kidney. These curves were analyzed by four different methods. Two of these methods are based upon measurement of the slopes of the uptake and washout curves from the liver and spleen and the other two methods employ deconvolution analysis to permit area measurement under the deconvolved curves as an indicator of blood flow. All four methods showed a small intraobserver variation after reanalysis. In 11 patients who underwent repeat studies, the correlation between the deconvolution based methods (r = 0.79-0.89) was significantly better than that for the slope based methods (r = 0.55-0.58). The deconvolution based methods provided the most significant separation between normals and patients with various liver disorders and would appear to be the most suitable techniques for monitoring the effects of various drugs and surgical procedures on the relative arterial/portal contribution to hepatic blood flow.

Hepatic Artery↗
PubMed1987

Immunotoxins to a human melanoma-associated antigen: resistance to pokeweed antiviral protein conjugates in vitro.

Pokeweed antiviral protein (PAP) from the summer leaves of Phytolacca americana was purified and conjugated via N-succinimidyl-3-(2-pyridyldithio)propionate to 9.2.27 anti-melanoma antibody to a glycoprotein-proteoglycan complex. The conjugate was highly potent (50% inhibition dose of 5 X 10(-11)-10(-13) M on antigen-positive melanoma) and highly selective (5 X 10(-8) on antigen-negative melanoma). Human melanoma cells were selected for resistance to in vitro killing of the PAP conjugate by cycling through a killing and recovery sequence. Resultant cultures were shown to be more than 2 logs less sensitive to the killing of the PAP conjugate than untreated cultures. Isolation of clones by limiting dilution and reanalysis indicated that the resistant polyclonal culture contained clones with a range of sensitivities. Resistant cultures were also resistant to other A-chain conjugates of 9.2.27, but not to intact toxins like ricin and abrin. Resistant cultures showed no change in antigen expression after selection with the PAP conjugate of 9.2.27. Thus, just as with many other chemotherapeutic agents, tumor cells can become resistant to agents inhibiting protein synthesis even when targeted with monoclonal antibody. The mechanisms of this resistance and modalities to minimize resistance are currently being explored.

Antibodies, Monoclonal↗
PubMed1987

Multipoint gene mapping using seriation. I. General methods.

Initial and accurate inference of locus order and estimates of interlocus distances and interference can be obtained using seriation techniques. The analysis requires a matrix of recombination values that can be estimated by standard pairwise linkage analysis. This allows combination of results from individual investigators without reanalysis of basic pedigree material. Seriation can be performed without the use of a computer.

Chromosome Mapping↗
PubMed1986

Precision of dual photon absorptiometry measurements.

One of the important uses of bone absorptiometry is to examine the rate of bone mineral change in order to evaluate therapy and to identify individuals who need therapy. Generally, this involves comparing the difference between two scans obtained months to years apart. This study investigates the precision of dual photon absorptiometry using a human torso phantom, normal subjects, and abnormal patients. These studies showed that bone mineral calculated as g/cm2 was more precise than g/cm. Reanalysis of the same scan by the same individual produced an average error equivalent to that produced by scanning and analyzing the same subject on multiple occasions. Interobserver analysis error was essentially equal to the intraobserver error. In order to obtain maximum precision, care must be taken that the integrated area of a repeat scan is identical to the previous scan. Our findings indicate that to be confident (95%) of a real change between two scans a difference of at least 5.6% must be measured.

Bone and Bones↗
PubMed1986

Muscular fatigue: effects of hydrogen ions and inorganic phosphate.

During muscular fatigue two metabolites, hydrogen ions (H+) and inorganic phosphate (Pi), increase in concentration. The effect of increase in [H+] has been modeled mathematically for a system containing creatine kinase (EC 2.7.3.2), adenylate kinase (EC 2.7.4.3), and the appropriate concentrations of their substrates. Assuming that no other equilibrium reactions are involved, the result of acidification should be a useful increase in the ratio [ATP]/[ADP]. It is also shown by a reanalysis of earlier 31P NMR studies that the observed combination of increased [H+] and increased [Pi] leads to an increase in the monobasic phosphate concentration [Pi-] that is inversely proportional to the force of contraction. This suggests that Pi- may be a direct inhibitor of the actomyosin ATPase system.

Animals↗
PubMed1987

Temperature-compensated ultradian variation in cellular protein content of Acanthamoeba castellanii revisited.

Synchronous cultures of the soil amoeba Acanthamoeba castellanii, established in the laboratory by selection procedures, show oscillations of total cell protein, as well as respiration. Previously, time series analysis by Aspect, a University of Warwick Computer Unit Program, showed an average period of 76 min. A reanalysis by least-squares rhythmometry revealed that, in general, the analyses accompanying the original paper and those in this replication agree very well. The periods extracted by the two approaches differ by only 1 to 5 min. In one case, when the original analysis did not detect a statistically significant period, however, the analysis used here does so. While the incubation temperatures used varied from 20 to 30 degrees C and cell division time increased from 7.8 hr at 30 degrees C to 16 hr at 20 degrees C, the metabolic bioperiodicity appeared to be temperature compensated. Decimation studies indicate that the sampling interval of 5 to 15 min must not be further reduced. It is promising to incorporate the study of ultradian metabolic rhythms into a broad spectral approach, i.e., for a concomitant assessment of ultradian, circadian, and infradian rhythms.

Activity Cycles↗
PubMed1987

Chronobiologic view of molt and longevity of Folsomia candida (Collembola) at different ambient temperatures.

A reanalysis of data published earlier indicates that the springtail, Folsomia candida, kept in continuous darkness, lengthens its intermolt interval (stadia) with age. At an environmental temperature of 21 degrees or 26 degrees C, the early stadia show an about-half-weekly or circasemiseptan interval and later stadia an about-weekly or circaseptan intermolt interval. At 15 degrees C, early stadia are about circaseptan, lengthening to nearly circadiseptan with aging. Our own studies of Folsomia candida at 23 degrees C show that the incidence of molting in 24 springtails observed at 3-hr intervals for 17 days is characterized by a prominent circadian rhythmicity and an infradian periodicity with a period of about 3 days. Both components are statistically highly significant (P = 0.001) when assessed concomitantly by least-squares rhythmometry.

Aging↗
PubMed1986

Gender-specific differences in family practice graduates.

In 1979 the American Academy of Family Physicians (AAFP) conducted a study of family practice residency graduates to develop a database of personal and professional characteristics. Questionnaires were sent to 4,295 physicians, and results were based on a total of 3,021 respondents. Female physicians made up 7.1 percent of this sample; however, analysis of the data at that time did not distinguish between men and women. The current study is a reanalysis of the data collected by the AAFP to include comparisons of male and female respondents and to determine whether gender differences that have been reported in the literature continue to persist. Results indicate that gender differences did persist in four of six areas studied; however, these differences were not so large as described in earlier studies. Areas in which differences were found are demographics, family structure, practice arrangements, and salary. Notable differences were not found in the areas of career choice development and professional activities. Now that the number of female physicians approaches 20 percent of all new family physicians, further data collection efforts are needed to determine their impact on family practice as a specialty.

Family Characteristics↗
PubMed1987

Hydrostatic theory and G protection using tilting aircrew seats.

A hydrostatic theory of blackout is generally supported in the acceleration literature, but there is disagreement as to the correct origin in the thorax for h, the hydrostatic distance to the eye. Our goal was to determine whether representative published data would preferentially support some particular origin for h. Based upon a reanalysis of published data (1) relating acceleration tolerance (T) to seat-back angle (theta), it was found that a simple hydrostatic model, with h measured from the aortic valve to the eye, yields an excellent fit. The nonlinear equation fitted was Ti = Tmin 1/cos(theta i-phi), where phi = correction to back angle. The value of phi derived from the 1975 data (1) (13.74 degrees) was the same as the independent estimate of phi for this same seat (13.06 degrees) derived from published values of h, which were measured by X-ray with h referenced to the aortic-valve and eye (2). The acceleration tolerance data for the other two seats of the 1984 study also strongly supported the model. Future studies should measure h (aortic valve-to-eye), use seat-back angles giving even spacing on a 1/h scale, and analyze data using the required nonlinear methods.

Acceleration↗
PubMed1979

Chemical characterization of 465 known or suspected carcinogens and their correlation with mutagenic activity in the Salmonella typhimurium system.

Since chemicals exhibiting mutagenic activity pose a potential hazard to their users, there is increasing acceptance of mutagenicity testing as an integral part of a premarketing toxicological evaluation of chemicals. In vitro testing has gained much notoriety as quick and relatively inexpensive means to assess the mutagenic potential of chemicals. However, the innovative use of microsomes to simulate metabolism has not changed the fact that in vitro activation cannot duplicate faithfully the metabolism that occurs in vivo. This shortcoming will express itself by the production of false negatives and possibly false positives during mutagenicity screening. This assertion is also borne out by a reanalysis of the ability of known animal carcinogens to cause mutations in the generally recognized premier in vitro system, the Salmonella-S-9 system. Although previous studies have suggested that a high percentage (greater than 85%) of all carcinogens will be mutagenic in this system, with no indication that false negatives are associated with certain chemical types, these findings are of uncertain practical value due to the limited number of chemical types that were considered. An analysis of 465 compounds with known or suspected carcinogenic activity indicates that about 58% have been adequately tested in Salmonella, that the testing has concentrated on certain chemical types and has neglected others, and that some categories of carcinogens exhibit individual correlations that are unsatisfactorily low by any standard. Poorly detected categories of carcinogens include: azonaphthols; carbamyls and thiocarbamyls; phenyls; benzodioxoles; polychlorinated aromatics, cyclics, and aliphatics; steroids; antimetabolites; and symmetrical hydrazines. Nonstandard procedures are necessary to optimize the testing of chemicals that are bactericidal, that are volatile, or that cross-link DNA. False negatives appear to arise for two reasons: an inability to devise an in vitro activation system that can be reliably used in a standard way; and an inability to detect the entire spectrum of mutational events that can lead to the induction of cancer.

Antimetabolites↗
PubMed1985

Detection of two distinct malignant B cell clones in a single patient using anti-idiotype monoclonal antibodies and immunoglobulin gene rearrangement.

Immunoglobulin gene rearrangement analysis and somatic cell hybridization techniques were used to examine the malignant cell population in an unusual patient with hairy cell leukemia and macroglobulinemia (N Engl J Med 296:92, 1977). Although previous investigations suggested that the IgM macroglobulin was secreted by the circulating leukemia cells, anti-idiotype monoclonal antibodies raised to the IgM macroglobulin failed to react with the malignant cells in the circulation and bone marrow. In contrast, approximately 50% of the mononuclear cells from an enlarged inguinal lymph node reacted strongly with the anti-idiotype antibodies. Subsequent reanalysis of all cell populations demonstrated that whereas the circulating and bone marrow cells were IgM kappa-bearing, the macroglobulin was IgM gamma-bearing and the lymph node cells were evenly divided among IgM kappa-bearing and IgM gamma-bearing. Immunofluorescence flow cytometry indicated that those lymph node cells that reacted strictly with the anti-idiotype antibody were IgM gamma-bearing, demonstrating that they were the source of macroglobulin. An analysis of immunoglobulin gene DNA confirmed the coexistence of two distinct malignant B cell populations in the lymph node and indicated that the IgM kappa-bearing lymph node cells were identical to the circulating and bone marrow leukemic cells.

Aged↗