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Abstract
Studies of inherited deafness disorders in mice and humans are providing new insights into the basis of hair-cell mechanosensitivity; this enterprise has been joined by large-scale genetic screening in the zebrafish, where a number of intriguing mutants defective in mechanosensation have recently been described.
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McNaughton S, Sauvé L, Ashmore J, Robson E. Drinking decisions. An innovative approach to problem drinking. THE CANADIAN NURSE 1998; 94:26-9. [PMID: 9677906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Abstract
As sensory cells, hair cells within the mammalian inner ear convert sounds into receptor potentials when their projecting stereocilia are deflected. The organ of Corti of the cochlea contains two types of hair cell, inner and outer hair cells, which differ in function. It has been appreciated for over two decades that although inner hair cells act as the primary receptor cell for the auditory system, the outer hair cells can also act as motor cells. Outer hair cells respond to variation in potential, and change length at rates unequalled by other motile cells. The forces generated by outer hair cells are capable of altering the delicate mechanics of the cochlear partition, increasing hearing sensitivity and frequency selectivity. The discovery of such hair-cell motility has modified the view of the cochlea as a simple frequency analyser into one where it is an active non-linear filter that allows only the prominent features of acoustic signals to be transmitted to the acoustic nerve by the inner hair cells. In this view, such frequency selectivity arises through the suppression of adjacent frequencies, a mechanical effect equivalent to lateral inhibition in neural structures. These processes are explained by the interplay between the hydrodynamic interactions among different parts of the cochlear partition and the effective non-linear behaviour of the cell motor.
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Katz RC, Ashmore J, Barboa E, Trueblood K, McLaughlin V, Mathews L. Knowledge of disease and dietary compliance in patients with end-stage renal disease. Psychol Rep 1998; 82:331-6. [PMID: 9520569 DOI: 10.2466/pr0.1998.82.1.331] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Noncompliance is a common problem in patients with end-stage renal disease. In this study, we assessed the relationship between knowledge of disease and dietary compliance in a cohort of 56 dialysis patients. Based on a health belief model of adherence, we predicted that dialysis patients who knew more about kidney disease and its treatment would be more complaint than those who knew less about these matters. We also examined the relationship between dietary compliance and patients' emotional well-being. We used a composite measure of compliance consisting of serum K, P, and interdialytic weight gain. A 30-item "Kidney Disease Questionnaire" was used to assess patients' knowledge of their illness. Contrary to prediction, compliers did not score higher on the knowledge questionnaire; in fact, the observed correlation of .32 was in the opposite direction. In the same vein, we found no relationship between compliance and emotional well-being. These results, although somewhat surprising, add to a growing body of research which indicates that medical compliance involves more than educating patients about the mechanisms and treatment of their illness.
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Abstract
Genetic mutations that lead to hearing losses have been identified in both human and mouse populations; the gene products include members of a class of unconventional myosins.
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Bell SC, Jackson JA, Ashmore J, Zhu HH, Tseng L. Regulation of insulin-like growth factor-binding protein-1 synthesis and secretion by progestin and relaxin in long term cultures of human endometrial stromal cells. J Clin Endocrinol Metab 1991; 72:1014-24. [PMID: 1708779 DOI: 10.1210/jcem-72-5-1014] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The decidualized endometrium during the first trimester of pregnancy synthesizes and secretes a 32-kDa insulin-like growth factor-binding protein (termed hIGFBP-1) at high levels. IGFBP-1 is the major soluble protein product of this tissue and is principally localized to the differentiated endometrial stromal cell, the decidual cell. In the present study long term culture of stromal cells from the nonpregnant endometrium have been employed to elucidate the hormonal requirements for IGFBP-1 production. Immunoreactive IGFBP-1 was undetectable in control cultures. However, inclusion of medroxyprogesterone acetate (MPA) induced rates of 0.35 +/- 0.09 microgram/0.1 mg cell DNA.day (mean +/- SEM; n = 5) after 20-30 days. In these cultures cells exhibited morphological changes consistent with decidual cell differentiation. In all cultures removal of MPA after exposure for 10-16 days, with or without subsequent inclusion of relaxin (RLX), increased production of IGFBP-1 450- to 4600-fold to rates of 150-710 micrograms/0.1 mg cell DNA.day or 26-131 micrograms/10(6) cells.day on days 24-26. The rates tended to be higher with the inclusion of RLX and were sustained in contrast to cultures without RLX, where rates fell by day 30. Individual cultures responded differently to RLX when added from the initiation of culture, with either a response similar to MPA alone or a cyclical change in production, achieving maximal rates of 190-290 micrograms/0.1 mg cell DNA.day. Cultures in which RLX alone induced high IGFBP-1 high production were obtained from endometrium during the progesterone-dominated luteal phase. In cultures exhibiting high rates of immunoreactive IGFBP-1 production, the protein represented their major secretory protein product. This was confirmed by [35S]methionine incorporation and the presence of IGFBP-1 as the predominant protein in serum-free culture medium. The immunoreactive IGFBP-1 isolated from culture medium was found to be identical, by a number of criteria, with IGFBP-1 derived from decidual tissue. These results were consistent with a primary role of progestin exposure, whether in vivo or in vitro, in converting endometrial stromal cells to cells potentially able to exhibit the high rates of IGFBP-1 production typical of the decidualized endometrium of pregnancy.
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Ashmore J. Cochlear neurophysiology: In one ear and out the other. Nature 1986; 320:16-7. [PMID: 3951544 DOI: 10.1038/320016a0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Ashmore J. Auditory physiology: splitting hairs over hearing? Nature 1984; 310:544-5. [PMID: 6462243 DOI: 10.1038/310544b0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Ashmore J, Gardner P, Walker K. A cilia tale there is yet to tell. NURSING TIMES 1979; 75:555. [PMID: 254119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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38
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Oliver JR, Wright PH, Ashmore J. The effect of somatostatin on glucose stimulated adenosine 3'-5',monophosphate accumulation and glucose oxidation by isolated rat islets of Langerhans. Exp Biol Med (Maywood) 1978; 158:458-61. [PMID: 210467 DOI: 10.3181/00379727-158-40225] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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39
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Billings RE, Murphy PJ, McMahon RE, Ashmore J. Aromatic hydroxylation of amphetamine with rat liver microsomes, perfused liver, and isolated hepatocytes. Biochem Pharmacol 1978; 27:2525-9. [PMID: 215158 DOI: 10.1016/0006-2952(78)90320-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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40
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Billings RE, McMahon RE, Ashmore J, Wagle SR. The metabolism of drugs in isolated rat hepatocytes. A comparison with in vivo drug metabolism and drug metabolism in subcellular liver fractions. DRUG METABOLISM AND DISPOSITION: THE BIOLOGICAL FATE OF CHEMICALS 1977; 5:518-26. [PMID: 21776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The metabolism of drugs in isolated rat hepatocytes has been investigated. Drugs which are metabolized by aromatic hydrolation, aliphatic hydroylation, N-demethylation, or glucuronidation have been used as substrates. With some substrates the rate of metabolism in isolated hepatocytes compares with that in hepatic 900g supernatant fraction or microsomes, but other substrates are metabolized at a slower rate in isolated hepatocytes. For example, the rate of butamoxane hydroxylation in isolated hepatocytes is slower than that in microsomes. However, the rate of hydroxylation is hepatocytes is identical to that in perfused liver. The metabolism of drugs in isolated hepatocytes correlates with in vivo drug metabolism better than does metabolism in the hepatic 9000g supernatant fraction or microsomes.
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Allen DO, Katocs AS, Gardner EA, Largis EE, Ashmore J. Perifused adipose cells, quantitation and kinetics of lipolysis. FEDERATION PROCEEDINGS 1977; 36:1991-4. [PMID: 193737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The perifused fat cell system is a system with which lipolytic activity can be monitored on a minute-to-minute basis. Thus, the rate at which lipolysis changes following the addition and removal of hormones can be followed. Catecholamines and other lipolytic agents produced a time-dependent increase in lipolysis following addition of agents, and a time-dependent decrease in lipolysis occurred following removal of the agent. ACTH also produced an increase in lipolysis. However, on termination of ACTH infusion, the lipolytic rate did not return to basal level but remained elevated for at least an additional 30 min (persistent phase). The persistent phase could be terminated by removal of Ca2+. Readdition of Ca2+ in the absence of additional ACTH resulted in a rapid increase in glycerol release. No persistant phase occurred following ACTH if the adipocytes were perifused in a Ca2+-free buffer. However, if Ca2+ was added to the system 20 min after termination of ACTH infusion, lipolysis increased to a rate greater than that obtained initially by infusing ACTH in a Ca2+-free buffer. It is concluded that ACTH is bound to some component of the fat cell in a Ca2+ independent, tenacious manner, and the full manifestation of that binding is dependent on the presence of Ca2+.
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Allen DO, Katocs AS, Largis EE, Ashmore J. Perifused fat cells-kinetic analysis of epinephrine-stimulated lipolysis. Biochem Pharmacol 1976; 25:103-5. [PMID: 1252250 DOI: 10.1016/0006-2952(76)90181-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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43
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Ashmore J, Cahill GF, Earle AS. STUDIES ON THE DISPOSITION OF ISOTOPIC GLUCOSE IN VIVO AND IN VITRO UNDER THE INFLUENCE OF SULFONYLUREAS. Ann N Y Acad Sci 1975. [DOI: 10.1111/j.1749-6632.1975.tb46738.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Moxley MA, Bell NH, Wagle SR, Allen DO, Ashmore J. Parathyroid hormone stimulation of glucose and urea production in isolated liver cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1974; 227:1058-61. [PMID: 4374088 DOI: 10.1152/ajplegacy.1974.227.5.1058] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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46
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Ingebretsen C, Clark JF, Allen DO, Ashmore J. Effect of glucagon, dibutyryl adenosine 3',5'-cyclic monophosphate and phosphodiesterase inhibitors on rat liver phosphorylase activity and adenosine 3',5'-cyclic monophosphate levels. Biochem Pharmacol 1974; 23:2139-46. [PMID: 4369954 DOI: 10.1016/0006-2952(74)90579-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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47
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Miller EA, Ingebretsen C, Clark JF, Ashmore J, Allen DO. Effects of glucagon and dibutyryl cyclic AMP on the phosphorylase activity and gluconeogenesis in rat liver slices. PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE. SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE (NEW YORK, N.Y.) 1974; 146:186-9. [PMID: 4363824 DOI: 10.3181/00379727-146-38066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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48
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Abstract
Concentrations of tolbutamide from 0.25 to 4.0 mg. per milliliter were found to inhibit epinephrine-stimulated lipolysis in isolated fat cells of the rat. At a concentration of 1 mg. per milliliter, tolbutamide also inhibited lipolysis stimulated by ACTH or dibutyryl cyclic AMP. At the same concentration it failed to alter basal lipolysis, basal or epinephrine-stimulated cyclic AMP levels. Basal and epinephrine-stimulated adenylate cyclase and glycogen phosphorylase as well as binding of cyclic AMP to protein kinase were unaltered. These data are discussed in relation to the antilipolytic mechanism of tolbutamide.
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49
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Katocs AS, Largis EE, Allen DO, Ashmore J. Perifused fat cells. Effect of lipolytic agents. J Biol Chem 1973; 248:5089-94. [PMID: 4352191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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50
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Largis EE, Allen DO, Clark J, Ashmore J. Isoproterenol and glucagon effects in perfused hearts from spontaneously hypertensive and normotensive rats. Biochem Pharmacol 1973; 22:1735-44. [PMID: 4351901 DOI: 10.1016/0006-2952(73)90387-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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