Change and choice: new dimensions of private practice.
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Fees, Medical↗
Biomedical subjects
R R Robinson
Publications and source records attributed to R R Robinson.
A simple, computer-assisted assay to detect isotype-specific regulation of human immunoglobulin synthesis.
A simple, reliable, and computer-assisted assay has been developed to quantitate isotype-specific regulation of human immunoglobulin synthesis in vitro. The assay utilizes three separate human lymphoblast or myeloma cell lines, which secrete human immunoglobulins IgA, IgG, and IgE. Culture supernatants from 96-well tissue culture plates are then assayed for IgA, IgG, and IgE by a solid-phase enzyme-linked immunosorbent assay (ELISA) on a microtiter plate. Data collection and analysis is performed with the aid of computer programs designed for this assay. This assay has several advantages over other immunoglobulin regulation assays: no radioisotopes are used, thereby reducing cost and complexity; results are directly collected and quantified by computer analysis; the entire assay is completed in 3 days; reliability and reproducibility are increased by the use of established human cell lines; and co-culturing all three immunoglobulin-producing cell lines provides convenient internal controls for isotype specificity.
Cell Line↗
Medical image management.
Medical image management is becoming increasingly complex as additional data are produced by equipment using digital techniques. As the requirements to store and display these images increase, the following questions become important: (a) What methods can be used to ensure that information given to the physician represents the originally acquired data? (b) What technology and methods are needed to guarantee that information is presented in a timely fashion when requested? (c) How can an image archiving and transmission system be designed to protect the patient's rights of confidentiality? The authors discuss the legal implications of digital archiving of image information and propose some approaches to designing systems that provide the most information to the physician and yet attempt to minimize infringement of the patient's rights.
Communication↗
Fate of sodium pentobarbital in rendered products.
The fate of pentobarbital through rendering was evaluated by following a group of euthanatized animals through a commercial rendering facility. Samples of material were collected at various points in the rendering process, and assays for pentobarbital were conducted by an ultraviolet spectrophotometric method. The results indicated that the pentobarbital, or a closely related analogue, survived rendering without undergoing degradation. The pentobarbital was distributed approximately equally between the meat and bone meal and tallow fractions. If pentobarbital-euthanatized animals are processed along with other raw materials throughout a day's production, the likelihood of significant residues being present in rendered products is minimal.
Animal Feed↗
Extensive polymorphism surrounding the murine Ia A beta chain gene.
A segment of the murine immune response-associated (Ia) antigen A beta chain mRNA has been cloned, and this cDNA clone has been used to examine the organization of the genes encoding these highly polymorphic cell surface proteins. To isolate this clone, pIA beta-1, we screened 5000 cDNA clones by a filter hybridization-selection assay using a rabbit heteroantiserum to identify the A beta chain produced in in vitro translation reactions. This clone corresponds to a segment of the mRNA encoding the beta chain of the murine I-A antigen. The 464 bp nucleotide sequence of the insert is consistent with a cDNA clone encoding the carboxyl end of the murine A beta chain. Comparison of this nucleotide sequence to a human Ia beta chain-derived cDNA clone suggests that the two clones could encode proteins that are about 90% homologous in this region. Southern blot analysis using pIA beta-1 as a probe to investigate the structure of the A beta chain gene in inbred strains of mice allows two conclusions. First, there is only one A beta chain gene homologous to this cDNA clone in each haploid mouse genome. Second, the restriction fragments encoding this gene are highly polymorphic. We postulate that the mechanism which generates polymorphic variation of the A beta chain may be involved in generating the restriction site polymorphism within or near the A beta chain gene.
Animals↗
Amphotericin B nephrotoxicity: increased renal resistance and tubule permeability.
Two groups of rats received amphotericin-B (Amp). One group (AA) received a single acute dose of 1 mg/kg i.v. The second (CA) received 10 mg/kg i.p. daily for 4 days. In AA rats, measurements 1 to 5 hr after Amp were compared with their own preinfusion values. Inulin clearance, (CIn, 4.5 ml X min-1 X kg-1 per kidney pre vs. 1.3 post), renal plasma flow (RPF, 12.0 ml X min-1 X kg-1 vs. 7.4), and the estimated pressure in the glomerular capillaries (Pgc, 52 mm Hg vs. 40), were all significantly decreased while renal vascular resistance (5.2 mm Hg/ml vs. 12.0) was increased. Only 45% of the 3H-inulin injected into surface tubules was recovered in the urine as contrasted with 100% recovery before injection. This suggests that tubule permeability was increased, but there was no histologic evidence of renal tubule necrosis. Twenty-four hours after intravenous Amp, CIn and RPF returned to normal. Data from CA rats were compared with values from sham-treated pairfed (PF) control rats. Again, CIn (4.22 ml X min-1 X kg-1 in PF vs. 2.69 in CA), RPF (16.1 ml X min-1 X kg-1 vs. 8.3), and Pgc (48 mm Hg vs. 38) were decreased, and renal vascular resistance (4.9 mm Hg/ml vs. 8.0) was increased. The recovery of 3H-inulin in the urine was slightly, but significantly, decreased (96% vs. 83%). These findings demonstrate that Amp decreases renal function by at least two mechanisms. An increase in renal vascular resistance is most important, although increased tubule permeability with a "backleak" of tubule fluid also contributes to renal dysfunction, particularly after intravenous Amp.
Amphotericin B↗
Fixed and reproducible orthostatic proteinuria: results of a 20-year follow-up study.
A 20-year follow-up evaluation of young men with fixed and reproducible orthostatic proteinuria showed no evidence of progressive renal disease. Follow-up information was obtained on 43 of the original 64 patients and detailed information was secured on 36. All had normal renal function and only six patients continued to show qualitative proteinuria. The prevalence of hypertension found was similar to that of a comparably aged group of the general population. The 20-year prognosis of patients with fixed and reproducible orthostatic proteinuria is excellent.
Adult↗
Physical activity and employment status of patients on maintenance dialysis.
Existing data on the clinical outcome of maintenance dialysis for end-stage kidney disease focus mainly on the duration of life. We surveyed 18 dialysis centers to gain a broader overview of the current status of 2481 patients on dialysis, irrespective of the type or location of dialysis. The results suggest that 12 per cent of dialysis patients are diabetics and that 53 per cent are 50 years of age or older. There was considerable variation among centers in the degree of rehabilitation; nevertheless, only 60 per cent of the nondiabetic patients and 23 per cent of the diabetic patients were capable of a level of physical activity beyond that of caring for themselves. Only one quarter of the patients worked outside the home, whereas one third worked at home. These results suggest that a larger proportion of dialysis patients than previously suspected are severely debilitated. There is a need for improved data on the quality and length of life of patients on maintenance dialysis.
Activities of Daily Living↗
Analysis of a drosophila tRNA gene cluster: two tRNALeu genes contain intervening sequences.
A recombinant DNA phage containing a cluster of Drosophila melanogaster tRNA genes has been isolated and analyzed. The insert of this phage has been mapped by in situ hybridization to chromosomal region 50AB, a known tRNA site. Nucleotide sequencing of the entire Drosophila tRNA coding region reveals seven tRNA genes spanning 2.5 kb of chromosomal DNA. This cluster is separated from other tRNA regions on the chromosome by at least 2.7 kb on one side, and 9.6 kb on the other. Two tRNA genes are nearly identical and contain intervening sequences of length 38 and 45 bases, respectively, in the anticodon loop. These two genes are assigned to be tRNALeu genes because of significant sequence homology with yeast tRNA3Leu, and secondary structure homology with yeast tRNA3Leu intervening sequence. In addition, an 8 base sequence (AAAAUCUU) is conserved in the same location in the intervening sequences of Drosophila tRNALeu genes and a yeast tRNA3Leu gene. Similar sequenes occur in all other tRNAs containing intervening sequences. The remaining five genes are identical tRNAIle genes, which are also identical to a tRNAIle gene from chromosomal region 42A. The 5' flanking regions are only weakly homologous, but each set of isoacceptors contains short regions of strong homology approximately 20 nucleotides preceding the tRNA coding sequences: GCNTTTTG preceding tRNAIle genes; and GANTTTGG preceding tRNALeu genes. The genes are irregularly distributed on both DNA strands; spacing regions are divergent in sequence and length.
Base Sequence↗
Isolated proteinuria in asymptomatic patients.
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Adult↗
Response of the collecting duct to disturbances of acid-base and potassium balance.
With light microscopy and scanning electron microscopy, the epithelium of the collecting duct was examined in rats with acute and chronic acid-base disturbances, hypokalemia, hyperkalemia, and during osmotic diuresis and hydropenia. Acid-base disturbances included acute respiratory acidosis, acute metabolic alkalosis, and chronic metabolic acidosis. Two groups of hypokalemic animals were studied, those with and those without an associated metabolic alkalosis. After the appropriate physiologic data were collected, all kidneys were preserved for morpholigic data were collected, all kidneys were preserved for morphologic evaluation by in vivo intravascular perfusion fixation. The percentage of intercalated cells in the epithelium of the collecting duct in the cortex and outer medulla of each kidney was determined by light microscopic examination of 1-mu-thick Epon sections stained with toluidine blue. Qualitative observations were performed with scanning electron microscopy. Intercalated cells represented 36 to 40% of the epithelial cells forming the collecting duct in the cortex and outer and inner stripes of the outer medulla in control animals during hydropenia and during mild osmotic diuresis. No experimental condition studied was found to influence significantly the actual or relative number of intercalated cells, or their distribution in the collecting duct. The hypertrophy of both principal cells and intercalated cells in potassium-depleted animals occurred in both the presence and the absence of metablic alkalosis. Conclusion. Under the conditions of this study, intercalated cells represent a constant population of epithelial cells in the rat collecting duct, and intercalated and principal cells represent distinct cell typs, each defined by rather constant morphologic features. Contrary to previous reports, no evidence was found that a disturbance of hydrogen ion and potassium balance is associated with a conversion of principal to intercalated cells in the collecting duct.
Acid-Base Imbalance↗
Spontaneously occurring animal models of human kidney diseases and altered renal function.
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Animals↗
Mechanisms and clinical significance of proteinuria in asymptomatic patients.
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Absorption↗
Relationship between para-aminohippurate secretion and cellular morphology in rabbit proximal tubules.
Previous studies in the mammalian proximal tubule have suggested that para-aminohippurate (PAH) secretion is approximately threefold greater in the straight segment, or pars recta, than in the convoluted segment, or pars convoluta. However, the possibility that the site of maximal PAH secretion might be related better to particular tubule segments as identified by cell type had not been explored. In addition, the presence or absence of differences in PAH secretion between morphologically identical regions of superficial (SF) vs. juxtamedullary (JM) proximal tubules has not been examined. These issues were studied using a combination of histologic methods and measurement of [(3)H]PAH secretion in isolated perfused tubules. Measurements of microdissected SF and JM proximal tubules from young and adult rabbits revealed that SF proximal tubules were slightly but significantly longer than JM tubules ([young rabbits: SF, 8.69+/-SE 0.14 mm vs. JM, 7.97+/-SE 0.13 mm; P < 0.01] [adult rabbits: SF, 10.61+/-SE 0.28 mm; JM, 9.17+/-SE 0.19 mm; P < 0.001]). Light and electron microscopy revealed three sequential segments (S(1), S(2), and S(3)) along the length of SF and JM proximal tubules as defined by cell type. PAH secretion was measured in each of these three segments by the isolated perfused tubule technique. Net PAH secretion in fmol/mm per min in SF proximal tubules was: S(1), 281+/-SE 21; S(2), 1,508+/-SE 104; S(3), 318+/-SE 46. Corresponding values in JM proximal tubules were 353+/-SE 31, 1,391+/-SE 72, and 188+/-SE 23. Net PAH secretion did not differ between comparable segments of SF and JM proximal tubules. It is concluded that differences in PAH secretion along the proximal tubule correlate best with cell type rather than the arbitrary division of the proximal tubule into pars convoluta and pars recta according to its external configuration. Evidence of functional heterogeneity between comparable segments of SF and JM proximal tubules was not observed.
Age Factors↗