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Biomedical subjects

M R Sutton

Publications and source records attributed to M R Sutton.

14 recordsLinked to original sources
PubMed1989

The hemodynamic properties of amlodipine in anesthetised and conscious dogs: comparison with nitrendipine and influence of beta-adrenergic blockade.

The hemodynamic actions of the new dihydropyridine calcium-channel blocker amlodipine were assessed and compared with those of nitrendipine using anesthetised dogs and were also investigated in conscious dogs with and without beta-adrenergic blockade. After bolus intravenous administration, amlodipine (25 to 1600 micrograms/kg) or nitrendipine (1 to 128 micrograms/kg) was administered to anesthetised dogs at 30-minute intervals, caused dose-related reductions in systemic and coronary vascular resistances with corresponding increases in cardiac output and coronary flow. Nitrendipine, unlike amlodipine, caused marked acute hypotension. The onset of action of amlodipine was markedly slower than that of nitrendipine, and effects were maintained for 30 minutes--recovery from nitrendipine was largely complete at 30 minutes. In conscious dogs, amlodipine (250, 500, 1000 micrograms/kg IV) caused dose-related reductions in systemic vascular resistance that approached maximum within 5 minutes and persisted for over 4 hours. Reflex increases in heart rate, cardiac output, and cardiac contractility were attenuated by prior treatment with propranolol, resulting in earlier and greater falls in blood pressure, but no marked adverse effects on cardiac contraction or conduction. In the absence of propranolol, maximum falls in blood pressure occurred 3 to 4 hours after the dose, possibly as a result of the changed baroceptor sensitivity induced by amlodipine. These results show amlodipine to have the basic hemodynamic profile of other dihydropyridine calcium-channel blockers, but in addition it demonstrates a slower onset and longer duration of action; the reasons behind these pharmacodynamic properties are discussed.

Adrenergic beta-Antagonists↗
PubMed1983

Evidence for central alpha-adrenergic transmission in a cardio-inhibitory response from the rabbit hypothalamus.

The heart rate of the anaesthetized rabbit was slowed by electrical stimulation of the hypothalamus with 7-9 sec trains of 250-330 microA pulses, duration 1 msec, frequency 60 Hz. This vagally-mediated cardio-decelerator response was attenuated in a dose-dependent manner after intravenous administration of phenoxybenzamine (0.01-5 mg/kg), phentolamine (0.01-3 mg/kg) or yohimbine (0.1-5 mg/kg). The attenuation of the cardio-decelerator response was not due to any vagolytic action of these drugs nor to block of the baroreceptor reflex, but appeared to be due to a central block of pathways descending from the hypothalamus. Propranolol, haloperidol, pimozide and spiperone did not show this central blocking action except in very large doses when there was evidence of some alpha-adrenoceptor blockade.

Adrenergic alpha-Antagonists↗
PubMed1982

Amino-terminal sequences of the L, M, and H subunits of reaction centers from the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26.

We have determined the sequence of the 25-28 amino-terminal residues of the three subunits, L, M, and H, of the membrane-bound reaction center protein of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26. The sequences are as follows: L, H2N-Ala-Leu-Leu-Ser-Phe-Glu-Arg-Lys-Tyr-Arg- Val-Pro-Gly-Gly-Thr-Leu-Val-Gly-Gly-Asn-Leu-Phe-Asp-Phe-(His)-Val-; M, H2N-Ala-Glu-Tyr-Gln-Asn-Ile-Phe-Ser-Gln-Val-Gln-Val-Arg-Gly-Pro-Ala-Asp-Leu-Gly-Met-Thr-Glu-Asp-Val-Asn-Leu-Ala-Asn-; H, H2N-Met-Val-Gly-Val-Thr-Ala-Phe-Gly-Asn-Phe-Asp-Leu-Ala-Ser-Leu-Ala-Ile-Tyr-Ser-Phe-Trp-Ile-Phe-Leu-Ala-X-Leu-Ile-. The H sequence, especially after the aspartyl residue at position 11, is rich in hydrophobic residues, consistent with the possibility that this section of the polypeptide chain is located within the membrane. The L sequence is hydrophilic near the amino terminus and then becomes moderately hydrophobic. The M sequence is of average polarity.

Amino Acid Sequence↗
PubMed1982

The complete amino acid sequence of human serum transferrin.

The complete amino acid sequence of human serum transferrin has been determined by aligning the structures of the 10 CNBr fragments. The order of these fragments in the polypeptide chain is deduced from the structures of peptides overlapping methionine residues and other evidence. Human transferrin contains 678 amino acid residues and--including the two asparagine-linked glycans--has an overall molecular weight of 79,550. The polypeptide chain contains two homologous domains consisting of residues 1-336 and 337-678, in which 40% of the residues are identical when aligned by inserting gaps at appropriate positions. Disulfide bond arrangements indicate that there are seven residues between the last half-cystine in the first domain and the first half-cystine in the second domain and therefore, a maximum of seven residues in the region of polypeptide between the two domains. Transferrin--which contains two Fe-binding sites--has clearly evolved by the contiguous duplication of the structural gene for an ancestral protein that had a single Fe-binding site and contained approximately 340 amino acid residues. The two domains show some interesting differences including the presence of both N-linked glycan moieties in the COOH-terminal domain at positions 413 and 610 and the presence of more disulfide bonds in the COOH-terminal domain (11 compared to 8). The locations of residues that may function in Fe-binding are discussed.

Amino Acid Sequence↗
PubMed1981

Vas micro-anastomosis. Fundamentals and modifications.

A study was undertaken to investigate 3 aspects of 2-layers vas reversal: 1) to determine an appropriate suture size for each layer, 2) to modify available instruments to make them more suitable for vas reversal surgery and 3) to devise a technique for a surgeon to perform alone.

Humans↗
PubMed1980

Microscoop method of doing 2-layer vas anastomosis.

The instruments and method that allow a single operator to do a 2-layer vas anastomosis under the microscope without the aid of an assistant are described. This method of anastomosis should be valuable for microsurgeons who wish to do a single layer anastomosis.

Humans↗
PubMed1977

Amino acid sequence of Escherichia coli biotin carboxyl carrier protein (9100).

The amino acid sequence of a proteolytic fragment of Escherichia coli biotin carboxyl carrier protein was determined from the structures of overlapping tryptic, thermolytic, and staphylococcal protease peptides together with automated sequenator analyses on the intact protein. The fragment, 82 residues in length, contains the single residue of biocytin of the protein. The relationship of the Mr = 9100 fragment to the native Mr = 22,500 subunit is discussed.

Amino Acid Sequence↗
PubMed1975

The amino-acid sequences of three cystine-free cyanogen-bromide fragments of human serum transferrin.

The amino acid sequences of three fragments obtained on cyanogen bromide cleavage of human transferrin have been determined. Two of the fragments are small (4 and 7 residues) and had not been isolated in previous studies of the CNBr fragments of transferrin. The sequence of the larger fragment (53 residues) was elucidated by examining peptides isolated from digests of the fragment with trypsin, chymotrypsin or thermolysin. This region of transferrin appears to contain the sites of three previously-reported substitutions in the D1 and D-chi genetic variants.

Amino Acid Sequence↗
PubMed1974

Purification and characterization of the seven cyanogen bromide fragments of human serum transferrin.

1. Procedures are described for the isolation of seven distinct cyanogen bromide fragments in high yield from human serum transferrin. 2. Cyanogen bromide-cleaved transferrin is separated into three fragments (CN-A, CN-B and CN-C) by gel filtration with Sephadex G-100. 3. Four peptides are obtained from CN-A (the largest fragment) after reduction and carboxamidomethylation, by gel filtration in acidic solvents. Two peptides are similarly obtained from fragment CN-B, whereas fragment CN-C is a single cystine-free peptide. 4. The molecular weights of the seven peptides, as determined by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate, by sedimentation-equilibrium ultracentrifugation and by sequence studies, range from 3100 to 27000. Together they account for a molecular weight of 76200 for transferrin. 5. The two largest fragments contain the carbohydrate attachment sites of the protein, and the smallest fragment is derived from the N-terminus. 6. The amino acid compositions and N-terminal groups of the fragments are reported and the results compared with those of previous investigations.

Amino Acid Sequence↗