Electron microscopy and pedigree study in an Ayrshire bull with tail-stump sperm defects.
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Animals↗
Biomedical subjects
L A Johnson
Publications and source records attributed to L A Johnson.
Analysis of variance of parameter estimates: F tests and t tests.
The problem of comparing and pooling experimentally independent estimates of a parameter such as a Michaelis constant (K) has been treated as a simple analysis of variance of "within" and "between" set deviations from the fitted variable (v). As applied to assessing the reproducibility of multiple estimates of the same K, this is identical to the procedure of Duggleby (Anal. Biochem. 189, 84-87, 1990). However, the theory developed here shows that applying Duggleby's procedure to the comparison of two experiments (each consisting of multiple data sets) depends critically on the assumption of equal errors within and between the individual sets, i.e., Fvb vw = s2wv/s2bv is close to 1. Application of the method when this is not the case will underestimate the common error (s2rv), overestimate its associated degrees of freedom (vr = vb+vw), and may suggest apparently significant differences where there are none. The theory also shows that this situation is an instance of the Fisher-Behrens problem and shows how Welch's solution can be applied. This gives the between set error s2bv as the corrected estimate of the common error and the corrected degrees of freedom as a simple function of vb, vw, and Fvb vw. When the nine prephenate dehydratase data sets which originally showed three apparently significant differences were reanalyzed in this way, all the variations in K were found to be within the range of the experimental error.
Analysis of Variance↗
Degradation of triglycerides by a pseudomonad isolated from milk: molecular analysis of a lipase-encoding gene and its expression in Escherichia coli.
Psychrotrophic lipolytic bacteria represent a significant problem in the storage of refrigerated dairy products. A lipase-encoding gene has been cloned and characterized from a highly lipolytic strain of Pseudomonas. The nucleotide sequence of the gene predicts a polypeptide of M(r) 49,905, which was identified when the gene was expressed in Escherichia coli.
Amino Acid Sequence↗
Quantitative chemical shift imaging of vertebral bone marrow in patients with Gaucher disease.
To evaluate extent of bone marrow involvement and disease severity in Gaucher patients, results of modified Dixon quantitative chemical shift imaging (QCSI) of the lumbar spine were correlated with quantitative analysis of marrow triglycerides and glucocerebrosides and with quantitative determination of splenic volume at magnetic resonance (MR) imaging. High-field-strength MR spectra of surgical marrow specimens were dominated by a single fat and a water peak, validating use of QCSI. QCSI showed average vertebral marrow fat fractions of 10% +/- 8 in Gaucher patients (normal adult averages, 29% +/- 6). Relaxation times for lipid and water approximated normal averages; bulk T1 values were significantly longer, reflecting decreased marrow fat. Glucocerebroside concentrations were higher in Gaucher marrow and inversely correlated with triglyceride concentrations. Extent of marrow infiltration determined by fat fraction measurements correlated with disease severity measured by splenic enlargement. These results show that as Gaucher cells infiltrate bone marrow and displace normal marrow adipocytes, bulk T1 increases due to the higher T1 of water compared with that of fat. QCSI provides a sensitive, noninvasive technique for evaluating bone marrow involvement in Gaucher disease.
Body Water↗
Multiple tumor suppressor genes in multistep carcinogenesis.
One of the most exciting areas of molecular oncology is the convergence of two independent lines of evidence suggesting involvement of multiple tumor suppressor genes in a given type of cancer. First, epidemiology and somatic cell genetics indicate the presence of multiple tumor suppressor genes in each of several malignancies. Second, cancers often lose multiple chromosomal regions during tumor progression. We will use two tumors, colorectal cancer and Wilms tumor, to illustrate the questions that multiple tumor suppressor genes raise.
Colorectal Neoplasms↗
A novel general strategy for cloning tumor suppressor genes using radiation-reduced chromosomal superfragments.
To identify the tumor suppressor gene on human chromosome 11p15, we generated mouse microcell hybrids containing small transferable chromosome 11p15 fragments, which we have termed "DNA superfragments". These hybrids will be used to identify which fragments contain a tumor suppressor gene by direct transfer of the fragments to tumor cells via microcell fusion.
Animals↗
Management of acute spinal trauma.
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Animals↗
A computer management system for patient simulations.
A series of interactive videodisc patient simulations is being used to teach clinical problem-solving skills, including diagnosis and management, to dental students. This series is called Oral Disease Simulations for Diagnosis and Management (ODSDM). A computer management system has been developed in response to the following needs. First, the sequence in which students perform simulations is critical. Second, maintaining records of completed simulations and student performance on each simulation is a time-consuming task for faculty. Third, the simulations require ongoing evaluation to ensure high quality instruction. The primary objective of the management system is to ensure that each student masters diagnosis. Mastery must be obtained at a specific level before advancing to the next level. The management system does this by individualizing the sequence of the simulations to adapt to the needs of each student. The management system generates reports which provide information about students or the simulations. Student reports contain demographic and performance information. System reports include information about individual patient simulations and act as a quality control mechanism for the simulations.
Computer Simulation↗
Iodine intake and the seasonal incidence of thyrotoxicosis in New Zealand.
We explored a possible relationship between the seasonal variation in the incidence of thyrotoxicosis in our area and iodine intake, as assessed by measuring the 24-h urinary iodide excretion rate eight times at 3-month intervals in a group of normal subjects and in 992 outpatient specimens over a 2-year period (1988-1990). For the period 1978-1990, 139 cases of thyrotoxicosis were diagnosed during the warmer half of the year (November-April) and 100 cases during the cooler half (May-October). This difference was statistically highly significant (P = 0.013). A similar disproportionality in the incidence of thyrotoxicosis was observed between the warmer (57%) and cooler (43%) halves of the year for the period 1988-1990. During the 1988-1990 period there was no discernible seasonal variation in either the milk iodide concentration or in the cumulative mean 24-h urinary iodide excretion rates for the normal subjects or the outpatients. We conclude that the higher proportion of thyrotoxic patients diagnosed during the warmer 6-month period of the year in our area is best explained by the fact that symptoms tend to be less tolerable in warm weather. A comparison of our findings on 24-h urinary iodide excretion rates with data collected in our area 25 years ago suggested that iodine intake may have declined.
Adult↗
Ascorbic acid interferes with an automated urinary iodide determination based on the ceric-arsenious acid reaction.
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Arsenates↗
A survey of the iodide concentration of human milk.
The iodide concentration of human milk from mothers living in the Wellington area and of six prepared infant formulae was measured. A total of 93 human milk samples were assayed, 14 from mothers of infants delivered at less than 35 weeks gestation and collected within 30 days of delivery (group A), 57 samples from mothers of infants delivered at 35 or more weeks gestation and collected within 60 days of delivery (group B) and 22 samples from mothers with infants aged greater than 60 days (group C). There was no significant (p greater than 0.05) difference between the means (SE) of groups A 1.14 mumol/L (0.20) and B 0.98 mumol/L (0.07). The mean for group C 0.39 mumol/L (0.03) was significantly less (p less than 0.05) than the means for both groups A and B. For groups A, B and C combined, there was a correlation (r = 0.44, p less than 0.01) between the milk iodide concentration and the iodide/creatinine ratio of a maternal urine specimen obtained immediately before or after the milk specimen. Formula milk preparations based on cow's milk contained higher concentrations of iodide than human milk.
Creatinine↗
Sperm DNA and sex chromosome differences between two geographical populations of the creeping vole, Microtus oregoni.
The relative DNA content of the "O" and Y chromosome-bearing sperm is presented for the creeping vole, Microtus oregoni. The animals had been trapped in Oregon and in Washington State. The two populations had very similar autosomal chromosome relationships but differed greatly in the size of their X chromosome (which is not carried by vole sperm) and in their Y chromosome. The greater size and banding differences of the Y chromosome of the Washington State vole compared to the Oregon vole paralleled the greater differences in sperm DNA between the Y-bearing sperm and the sperm carrying no sex chromosome (O). The actual DNA differences between O and Y sperm was 12.5% for the sperm from the Washington State voles and 9.1% for sperm from the Oregon voles. The difference in sperm DNA content (12.5%) for Washington State voles was far greater than the difference shown for other voles or other mammals.
Animals↗
Thymocytes stimulate metabolism of arachidonic acid in rat thymic epithelial cells.
Arachidonic acid metabolites play an important role in the development of T cells in the thymus. In the normal animal, prostaglandin levels in the thymus are significantly higher than in plasma. Herein, we have studied the regulation of arachidonic acid metabolism using the thymic endocrine epithelial cell line, TEA3A1, and thymocytes. We have found that TEA3A1 cells, but not thymocytes, produced prostaglandins and thromboxanes. We have also found that thymocytes could stimulate the production of arachidonic acid metabolites in TEA3A1 cells when both cells were cocultured. The strongest stimulation was observed when TEA3A1 cells were cocultured with thymocyte subpopulations either negative for OX8 or W3/25 functional surface markers (either double-negative or single-positive thymocytes). Furthermore, cell-cell contact seems to be absolutely required for the activation of arachidonic acid metabolism in TEA3A1 cells. The study presented here describes the existence of a novel regulatory mechanism of arachidonic acid metabolism which may play an important role in the development of T cells in the thymus.
Animals↗
Patient simulation consortium.
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Computer Simulation↗
Crohn's disease uveitis. Parasitization of vitreous leukocytes by mollicute-like organisms.
Crohn's disease (CD) is an idiopathic chronic inflammatory gut disease with frequent extragut inflammatory manifestations in the eyes, orbit, lungs, joints, and skin. A bacterial cause of CD is suspected, but cultivation of a specific pathogen has not been forthcoming. Mollicute-like organisms (MLOs) were recently reported to cause human chronic ocular inflammatory disease. Inoculation of this MLO into mouse eyelids produced chronic progressive granulomatous ocular and orbital inflammatory disease. In addition, MLOs disseminated to produce similar disease in the gut, heart, and lungs. MLOs are noncultivable cell wall-deficient bacterial pathogens. Because they also pass bacteria-retaining 0.450-micron filters, they can be overlooked or confused with viruses. Because MLOs have a characteristic ultrastructural appearance, they can be identified in diseased cells with the use of a transmission electron microscope. MLOs parasitize and destroy leukocytes. They alter the nucleus, replace the cytoplasm, and destroy organelles. MLO-caused disease is treatable by certain antibiotics. This report describes MLO-parasitized vitreous lymphocytes, monocytes, and polymorphonuclear leukocytes from three patients with CD who had chronic uveitis. The results indicate that MLOs probably caused the uveitis of these patients with CD. The gut as the possible source of the MLO is suggested. Rifampin therapy of Crohn's and MLO-caused disease is discussed.
Adult↗
Sex preselection in rabbits: live births from X and Y sperm separated by DNA and cell sorting.
Intact, viable X and Y chromosome-bearing sperm populations of the rabbit were separated according to DNA content with a flow cytometer/cell sorter. Reanalysis for DNA of an aliquot from each sorted population showed purities of 86% for X-bearing sperm and 81% for Y-bearing sperm populations. Sorted sperm were surgically inseminated into the uterus of rabbits. From does inseminated with sorted X-bearing sperm, 94% of the offspring born were females. From does inseminated with sorted Y-bearing sperm from the same ejaculates, 81% of the offspring were males. The probability of the phenotypic sex ratios differing from 50:50 were p less than 0.0003 for X-sorted sperm and p less than 0.004 for Y-sorted sperm. Thus, the phenotypic sex ratio at birth was accurately predicted from the flow-cytometrically measured proportion of X- and Y-bearing sperm used for insemination.
Animals↗
Isolation, molecular characterization and expression of the ushB gene of Salmonella typhimurium which encodes a membrane-bound UDP-sugar hydrolase.
The UDP-sugar hydrolase of Salmonella typhimurium has previously been reported to be located in both the inner and the outer membrane. We have cloned the gene, designated ushB, encoding this enzyme and determined its nucleotide sequence. No significant sequence homology with the periplasmic UDP-sugar hydrolase of Escherichia coli was found at either the DNA or protein level. However, a sequence is detectable, in the E. coli genome, which weakly hybridizes with a specific ushB probe. Polypeptide analysis has allowed the identification of the Salmonella hydrolase which has an Mr of 28,349 as compared to an Mr of 60,767 for the E. coli hydrolase. Most of the protein (approximately 90%) is located in the inner membrane. Two independent membrane fractionation procedures indicate that the remainder may be associated with the outer membrane. The deduced primary structure indicates the presence of an N-terminal signal peptide, although certain features of the region surrounding the putative processing site indicate that processing may be inefficient, or may not occur. Experiments with several inhibitors of signal peptidase function fail to demonstrate the appearance of a precursor form.
Amino Acid Sequence↗
Inactivation of chymotrypsin and human skin chymase: kinetics of time-dependent inhibition in the presence of substrate.
The reaction of chymase, a chymotryptic proteinase from human skin, and bovine pancreatic chymotrypsin with a number of time-dependent inhibitors has been studied. An integrated equation, relating product formation with time, has been derived for the reaction of enzymes with time-dependent inhibitors in the presence of substrate. This is based on a two-step model in which a rapidly reversible, non-covalent complex (EI) is formed prior to a tighter, less readily reversible complex (EI)*). The equation depends on the simplifying assumption [I] much greater than [E], but is applicable to reversible and irreversible slow-binding and tight-binding inhibitors whether or not they show saturation kinetics. The method has been applied to the reaction of chymase and chymotrypsin with the tetrapeptide aldehyde, chymostatin, basic pancreatic trypsin inhibitor and Ala-Ala-Phe-chloromethylketone (AAPCK). The irreversible inhibitor, AAPCK, showed the expected saturation kinetics for both enzymes and the apparent first-order rate constants (k2) and dissociation constants (Ki) for the non-covalent complexes were determined. Chymostatin was a much more potent inhibitor which failed to show a saturation effect. The second-order rate constant of inactivation (k2/Ki), the first-order reactivation rate constant (k-2), and the dissociation constant of the covalent complex (Ki*) were determined. Basic pancreatic trypsin inhibitor, a potent inhibitor of chymotrypsin, had similar kinetics to chymostatin but failed to inhibit chymase. The applicability of the two-step model and the integrated equation to slow- and tight-binding inhibitors is discussed in relation to a number of examples from the literature.
Amino Acid Chloromethyl Ketones↗