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I Kay

Publications and source records attributed to I Kay.

13 recordsLinked to original sources
PubMed1995

Cross reactivity studies of CRF-related peptides on insect Malpighian tubules.

Manduca sexta diuretic peptide II (Mas-DPII) stimulates fluid secretion by adult Malpighian tubules and cyclic AMP production by larval proximal and adult tubules of M. sexta in a dose-dependent manner. Mas-DPII has no effect on fluid transport across the larval cryptonephric complex. M. sexta diuretic hormone (Mas-DH) and CRF-related insect diuretic peptides from Acheta domesticus, Locusta migratoria, and Periplaneta americana also cause similar increases in the production of cyclic AMP by the Malpighian tubules of both larval and adult M. sexta. Insect CRF-related diuretic peptides exhibit varying degrees of potency when assayed on Malpighian tubules from L. migratoria and A. domesticus. Sauvagine, bovine-CRF, and human-CRF have only a small, but significant, effect on cyclic AMP production by M. sexta Malpighian tubules. However, sauvagine, bovine-CRF, and sucker fish urotensin-I have no effect on L. migratoria tubules. Stimulation of cyclic AMP production by M. sexta Malpighian tubules could potentially be used as a screening assay to identify other insect CRF-related diuretic peptides.

Aging↗
PubMed1994

Electrospray mass spectrometric characterization of the components of protein mixtures and its application to members of the chemokine family of interleukins.

Electrospray mass spectrometry has been employed to detect and characterize the members of a closely related family of immunologically active proteins (chemokines) produced in cell culture by stimulated fibroblasts. The reliability of the method to produce precise data concerning the relative proportions of proteins present in mixtures was investigated in a model system and found to be satisfactory in a range of 10:1 in concentration.

Cells, Cultured↗
PubMed1994

Isolation and characterization of a diuretic peptide common to the house fly and stable fly.

An identical CRF-related diuretic peptide (Musca-DP) was isolated and characterized from whole-body extracts of the house fly, Musca domestica, and stable fly, Stomoxys calcitrans. The peptide stimulates cyclic AMP production in Manduca sexta Malpighian tubules and increases the rate of fluid secretion by isolated Musca domestica tubules. The 44-residue peptide, with a mol.wt. of 5180, is amidated, and has the primary structure: NKPSLSIVNPLDVLRQRLLLEIARRQMKENTRQVELNRAILKNV-NH2. Musca-DP has a high percentage of sequence identity with other characterized CRF-related insect diuretic peptides.

Amino Acid Sequence↗
PubMed1994

Localization of Locusta-DP in locust CNS and hemolymph satisfies initial hormonal criteria.

Locusta-diuretic peptide (Locusta-DP) is a potent stimulant of fluid secretion and cyclic AMP production by locust Malpighian tubules. In this study, a polyclonal antiserum raised to the C-terminus of Locusta-DP reveals a wide distribution of immunoreactive cell bodies and processes throughout the CNS, and endings in two important neurohemal release sites: the corpora cardiaca and the perivisceral organs. HPLC fractionation of CNS, neurohemal structures, and hemolymph reveals immunoreactive material that coelutes with synthetic Locusta-DP and stimulates cyclic AMP production by locust tubules. The identity of the immunoreactive and biologically active material is confirmed as authentic Locusta-DP by mass spectrometry.

Animals↗
PubMed1992

Isolation, characterization and biological activity of a CRF-related diuretic peptide from Periplaneta americana L.

A diuretic peptide (Periplaneta-DP) has been isolated from extracts of whole heads of the cockroach, Periplaneta americana. The purified peptide increases cyclic AMP production and the rate of fluid secretion by isolated Malpighian tubules in vitro. In the fluid secretion assay, the response to native Periplaneta-DP is comparable to that obtained with crude extracts of cockroach corpora cardiaca, and the EC50 lies between 10(-8) and 10(-9) M. The primary structure of Periplaneta-DP was established as a 46-residue amidated peptide: T G S G P S L S I V N P L D V L R Q R L L L E I A R R R M R Q S Q D Q I Q A N R E I L Q T I-NH2. Periplaneta-DP is a further member of the recently established family of CRF-related insect diuretic peptides.

Amino Acid Sequence↗
PubMed1991

Practical implementation and optimization of one-shot T1 imaging.

Longitudinal relaxation times (T1) can be measured rapidly in an imaging context using a "one-shot" method based on the pulse sequence originally proposed by D. C. Look and D. R. Locker (Rev. Sci. Instrum. 41, 250 1970). This sequence is significantly faster than either repeated inversion recovery or repeated saturation recovery methods. The method uses a 180 degrees inversion pulse followed by multiple small-angle alpha pulses that sample the longitudinal magnetization during its recovery. Choices of inversion pulse, tip angle, and time intervals are discussed for optimal clinical use. We can produce 29 images sampling the full T1 recovery curve with a 256 x 256 resolution in about 10 min. From this data, T1 images can be calculated with a precision of 10%.

Humans↗
PubMed1991

Isolation and characterization of a diuretic peptide from Acheta domesticus. Evidence for a family of insect diuretic peptides.

A diuretic peptide (Acheta-DP) has been isolated from extracts of whole heads of the house cricket, Acheta domesticus. The native peptide increases both cyclic AMP production and the rate of fluid secretion by isolated Malpighian tubules in vitro to an extent comparable with those responses obtained with supra-maximal amounts of crude extracts of corpora cardiaca. The primary structure of Acheta-DP was established as a 46-residue amidated peptide: TGAQSLSIVAPLDVLRQRLMNELNRRRMRELQGSRIQQNRQLLTSI-NH2. Acheta-DP has 41% sequence identity with a diuretic peptide isolated from Manduca sexta, providing direct evidence for the presence of a family of diuretic peptides in insects.

Amino Acid Sequence↗
PubMed1991

Characterization of a diuretic peptide from Locusta migratoria.

A diuretic peptide Locusta-DP, identified by its ability to increase cyclic AMP production in locust Malpighian tubules in vitro, has been isolated and characterized from whole heads of Locusta migratoria. The purified peptide stimulates fluid secretion by Malpighian tubules maximally in vitro. The primary structure of Locusta-DP was established as a 46 residue amidated peptide: MGMGPSLSIVNPMDVLRQRLLLEIARRRLRDAEEQIKANKDFLQQI-NH2. Locusta-DP has 48% sequence identity with Acheta-DP and 49% identity with Manduca-DH, and provides further evidence for the presence of a family of diuretic peptides in insects.

Amino Acid Sequence↗
PubMed1984

Amiodarone-digoxin interaction: clinical significance, time course of development, potential pharmacokinetic mechanisms and therapeutic implications.

Administration of amiodarone (600 to 1,600 mg/day) to 28 patients during long-term digoxin therapy (0.25 +/- 0.05 mg/day) increased serum digoxin level from 0.97 +/- 0.45 to 1.98 +/- 0.84 ng/ml (p less than 0.001). Gastrointestinal side effects occurred in nine patients, central nervous system reactions occurred in five and cardiovascular reactions occurred in four. Pharmacokinetic studies in six patients with a 1 mg intravenous digoxin dose before and during amiodarone therapy increased serum digoxin level at 30 minutes from 8.59 +/- 1.68 to 10.07 +/- 1.70 ng/ml (p less than 0.05). Amiodarone caused a 31% prolongation of digoxin elimination half-life from 49.5 +/- 8.8 to 65.0 +/- 28.8 hours, but the increase in half-life was not statistically significant. Total body clearance was reduced significantly (29%, p less than 0.05) from 2.05 +/- 0.76 to 1.46 +/- 0.64 ml/min per kg. Nonrenal clearance also showed a significant decrease (33%, p less than 0.05) from 1.20 +/- 0.46 to 0.80 +/- 0.30 ml/min per kg. The renal clearance decreased by 22% and the volume of distribution decreased by 11% after amiodarone therapy, but these changes were not significant. The data show that the mechanism of digoxin-amiodarone interaction is multifactorial and emphasize the need for close monitoring of serum digoxin levels and clinical features during concurrent digoxin-amiodarone therapy.

Adult↗
PubMed1982

Entrainment of the circadian rhythm from the eye of Aplysia: role of serotonin.

The finding that serotonin (5-HT) treatments as short as 1.5 h in duration produce phase shifts in a circadian rhythm from the isolated eye of Aplysia suggested that release of 5-HT was part of an ocular entrainment pathway. Since light cycles entrain this rhythm, we compared phase shifting by 5-HT and by light. The similarity in the shapes of the phase-response curves for 5-HT and light pulses indicates that 5-HT treatments are capable of entraining the rhythm. Also, "skeleton" 5-HT treatments phase shift as well as continuous 5-HT treatments. However, 5-HT does not appear to mediate the phase shifts produced by light, since 1) treatments that should block transmitter release do not change the phase shifts produced by light pulses; 2) the response curves of 5-HT and light pulses are displaced by 12 h relative to one another on the phase axis of the response curve; and 3) light-induced phase shifts are apparent almost immediately, whereas 5-HT-induced phase shifts become evident only about 24 h after 5-HT treatment. The eye appears to contain two independent entrainment pathways, one for light and one utilizing 5-HT.

Animals↗
PubMedDate not supplied

High quality zoomed MR images.

A zooming technique based on zero filling of the Fourier space is presented for high quality magnification of magnetic resonance magnitude images. Comparison with conventional linear interpolation methods on two clinical examples indicates that Fourier magnification is preferable because it avoids image artifacts and provides superior image quality. It is recommended that this technique become the standard method of magnification on all imagers.

Fourier Analysis↗
PubMedDate not supplied

Receiver operator characteristic (ROC) analysis without truth.

Receiver operator characteristic (ROC) analysis, the preferred method of evaluating diagnostic imaging tests, requires an independent assessment of the true state of disease, which can be difficult to obtain and is often of questionable accuracy. A new method of analysis is described which does not require independent truth data and which can be used when several accurate tests are being compared. This method uses correlative information to estimate the underlying model of multivariate normal distributions of disease-positive and disease-negative patients. The method is shown to give results equivalent to conventional ROC analysis in a comparison of computed tomography, radionuclide scintigraphy, and magnetic resonance imaging for liver metastasis. When independent truth is available, the method can be extended to incorporate truth data or to evaluate the consistency of the truth data with the imaging data.

Calibration↗