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Biomedical subjects

S Miller

Publications and source records attributed to S Miller.

At least 415 records · Page 23Linked to original sources
PubMed1989

Isolation and characterization of histones from Anopheles albimanus Weidemann.

1. Histones from Anopheles albimanus adults were prepared by a combination of techniques including chromatin isolation and selective extractions. 2. The anopheline histones were identified on acid urea gels by comparing their electrophoretic profile with that of calf thymus histones and histones isolated from other tissue. 3. Excellent separation of histones was obtained after the extractions by a single electrophoretic run. 4. In addition to the five major classes of histones found in eukaryotes, a sixth class was detected and tentatively identified as histone H5. 5. This is the first report of histone H5 and its function in insects.

Animals↗
PubMed1989

Spouse and parent-offspring similarities in cardiovascular response to mental arithmetic and isometric hand-grip.

Thirty spouse pairs were recruited for a stress protocol consisting of alternating stress and relaxation periods. Repeated measurements of blood pressure, heart rate, and blood volume pulse were obtained. Spouse pairs were parents of young adult sibling pairs who had previously participated in a slightly different version of the protocol. Although spouses exhibited some behavioral similarities, there were no significant similarities in cardiovascular response to stress. However, despite the fact that parents and their offspring were tested on different occasions using somewhat different procedures, some similarities in cardiovascular reactivity were observed. Significant parent-offspring similarities in heart-rate response to mental arithmetic and diastolic blood pressure response to isometric hand-grip were observed, as well as several behavioral similarities. Assortative mating and the nature of one's current home environment seem to be less important in the familial aggregation of cardiovascular reactivity to stress than early environmental and/or genetic factors.

Adolescent↗
PubMed1989

The structure of interfaces between subunits of dimeric and tetrameric proteins.

The structures of the interfaces of nine dimeric and nine tetrameric proteins have been analyzed and have been seen to follow general principles. These interfaces are combinations of four structural motifs, which resemble features of monomeric proteins. These are: (i) extended beta sheet; (ii) helix-helix packing; (iii) sheet-sheet packing; and (iv) loop interactions. Other common structural features in the interfaces studied are two-fold symmetry, charged hydrogen bonds and channel formation (found only in tetramers). Monomer-monomer interfaces are intermediate in hydrophobicity and charge between the interfaces between secondary structures of monomeric proteins and the exteriors of monomeric proteins. A typical interface has one of the first three of the structural motifs at its centre and loop interactions around the outside, where most of the charge resides.

Molecular Structure↗
PubMed1989

The use of adaptive algorithms for obtaining optimal electrical shimming in magnetic resonance imaging (MRI).

A method of determining the dc coil current values to electrically shim the static magnetic fields used in magnetic resonance imaging (MRI) using modified steepest descent adaptive algorithm is described. Using a 32 cm diameter by a 40 cm long water phantom as the test volume, the algorithm achieved field homogeneities of 0.2 parts per million (ppm) peak-to-peak within a 20 cm diameter spherical imaging volume, and 1.3 ppm peak-to-peak within the entire phantom. The algorithm achieved an inhomogeneity variance of 0.18 ppm2. The shim system was successfully modeled as a sum of adaptive linear combiners. The model contains 13 parameters that can be varied, 12 shim coil currents, and the receiver mixer frequency. The model was then used to predict key adaptive algorithm parameters. Experimental verification of these parameters lends support to the accuracy of the model.

Algorithms↗
PubMed1989

The effect of chorda tympani section on ipsilateral and contralateral salivary secretion and taste in man.

Bilateral chorda tympani section is an accepted treatment for troublesome sialorrhoea. Nevertheless the effects of this operation have been poorly studied. Twenty patients were studied with unilateral chorda tympani section and a healthy contralateral ear. The effects on ipsilateral and contralateral stimulated submandibular and parotid flow and taste recognition and detection thresholds were measured. Stimulated submandibular flow accounted for only 27% of the total salivary flow. Chorda tympani section had no effect on submandibular flow in seven patients and only reduced submandibular flow by approximately 54% in the remaining 13 patients. No significant effect was observed on ipsilateral parotid flow rate. Electrogustometric taste detection thresholds were more than twice the accepted upper limit of normal on the lesioned side and taste recognition thresholds were also markedly abnormal. Chorda tympani section alone is a poor method of reducing stimulated salivary flow.

Adolescent↗
PubMed1989

Phaeohyphomycosis of the nasal sinuses caused by Bipolaris species.

Phaeohyphomycosis of the nasal sinuses of three patients is reported. Diagnosis is based on the laboratory findings of the biopsy tissue from the sinus lesions. All cases demonstrate a localized opportunistic infection caused by the dematiaceous fungus Bipolaris spicifera.

Adult↗
PubMed1989

Misoprostol heals gastroduodenal injury in patients with rheumatoid arthritis receiving aspirin.

High-dose aspirin therapy for rheumatoid arthritis is frequently associated with severe gastrointestinal injury. To explore the possibility of reversing such damage, we conducted a double-blind, multicenter study with misoprostol, a prostaglandin E1 analog, which has demonstrated mucosal protective, gastric antisecretory, and ulcer healing properties. We also studied possible interference of misoprostol with continuing aspirin treatment in the management of patients with rheumatoid arthritis. Patients with confirmed rheumatoid arthritis and endoscopically documented gastroduodenal lesions were randomly assigned to receive 200 micrograms of misoprostol four times a day (123 patients) or placebo (116 patients). Each concurrently received 650 to 1300 mg of aspirin four times a day. After eight weeks of treatment, misoprostol was statistically superior to placebo in healing gastric mucosal injury (70% vs 25%) and duodenal mucosal injury (86% vs 53%). Patients with gastric or duodenal ulcers on admission had superior ulcer healing rates with misoprostol (67% vs 26%). There was no evidence of interference with the antirheumatic properties of aspirin. Mild to moderate adverse experiences were equally noted in misoprostol and placebo groups. Misoprostol, coadministered with aspirin, is well tolerated and highly effective in healing aspirin-associated gastroduodenal lesions in patients with rheumatoid arthritis without altering the therapeutic benefits of aspirin.

Adult↗
PubMed1988

Surface, subunit interfaces and interior of oligomeric proteins.

The solvent-accessible surface area (As) of 23 oligomeric proteins is calculated using atomic co-ordinates from high-resolution and well-refined crystal structures. As is correlated with the protein molecular weight, and a power law predicts its value to within 5% on average. The accessible surface of the average oligomer is similar to that of monomeric proteins in its hydropathy and amino acid composition. The distribution of the 20 amino acid types between the protein surface and its interior is also the same as in monomers. Interfaces, i.e. surfaces involved in subunit contacts, differ from the rest of the subunit surface. They are enriched in hydrophobic side-chains, yet they contain a number of charged groups, especially from Arg residues, which are the most abundant residues at interfaces except for Leu. Buried Arg residues are involved in H-bonds between subunits. We counted H-bonds at interfaces and found that several have none, others have one H-bond per 200 A2 of interface area on average (1 A = 0.1 nm). A majority of interface H-bonds involve charged donor or acceptor groups, which should make their contribution to the free energy of dissociation significant, even when they are few. The smaller interfaces cover about 700 A2 of the subunit surface. The larger ones cover 3000 to 10,000 A2, up to 40% of the subunit surface area in catalase. The lower value corresponds to an estimate of the accessible surface area loss required for stabilizing subunit association through the hydrophobic effect alone. Oligomers with small interfaces have globular subunits with accessible surface areas similar to those of monomeric proteins. We suggest that these oligomers assemble from preformed monomers with little change in conformation. In oligomers with large interfaces, isolated subunits should be unstable given their excessively large accessible surface, and assembly is expected to require major structural changes.

Amino Acids↗
PubMed1988

The origin of mutants.

Nucleic acids are replicated with conspicuous fidelity. Infrequently, however, they undergo changes in sequence, and this process of change (mutation) generates the variability that allows evolution. As the result of studies of bacterial variation, it is now widely believed that mutations arise continuously and without any consideration for their utility. In this paper, we briefly review the source of this idea and then describe some experiments suggesting that cells may have mechanisms for choosing which mutations will occur.

Arabinose↗
PubMed1988

Comparison of cefoperazone and mezlocillin with imipenem as empiric therapy in febrile neutropenic cancer patients.

Seventy-eight patients with cancer experienced 88 episodes of fever while neutropenic and were randomly assigned to receive empiric antibiotic therapy with cefoperazone 2 g intravenously every 12 hours and mezlocillin 4 g intravenously every six hours or imipenem/cilastatin 500 mg intravenously over 30 to 60 minutes every six hours. Within 96 hours of starting antibiotic treatment, 24 patients (57 percent) treated with cefoperazone and mezlocillin and 34 patients (74 percent) receiving imipenem/cilastatin became afebrile. One half of the patients in each arm required changes in the antibiotic regimen because of side effects, persistent fever with a site suspicious for infection, resistant organisms, or breakthrough bacteremias. Forty patients (95 percent) receiving cefoperazone and mezlocillin and 43 patients (93 percent) receiving imipenem/cilastatin recovered from the neutropenic episode. Two patients in each regimen group died of their underlying disease. One patient in the imipenem/cilastatin arm died of Pseudomonas aeruginosa sepsis. Although the two regimens are comparable in efficacy, the incidence of side effects favored the cefoperazone and mezlocillin group. No seizures or bleeding were seen in either arm; however, 19 patients (41 percent) receiving imipenem/cilastatin required pretreatment antiemetic drugs for nausea.

Adult↗
PubMed1988

Profiles of prostaglandin biosynthesis in normal lung and tumor tissue from lung cancer patients.

prostaglandin (PG) biosynthetic profiles from endogenous arachidonic acid were determined by capillary gas chromatography-mass spectrometry in matched fresh normal lung (NL) and lung cancer (LC) tissue fragments obtained from 42 individual LC patients at the time of diagnostic thoracotomy. The histological diagnoses represented were squamous cell carcinoma (N = 20), adenocarcinoma (N = 7), small cell carcinoma (N = 4), mixed cell carcinoma (N = 2), bronchioloalveolar cell carcinoma (N = 2), large cell undifferentiated carcinoma (N = 3), bronchial carcinoid (N = 1), and metastatic tumors (N = 3). When PG biosynthesis was determined in NL tissue separately, low mean levels of PGE2 and PGF2 alpha (less than 2 pmol/mg protein/15 min), intermediate levels of PGD2 and 6-keto-PGF1 alpha (6KPGF1 alpha) (2-7 pmol/mg protein/15 min), and high levels of thromboxane B2 (TXB2) (greater than 7 pmol/mg protein/15 min) were observed. There was no particular correlation with cigarette smoking history and PG biosynthesis in NL. When PG production in LC tissue was evaluated separately, high levels of PGE2, PGF2 alpha, and 6KPGF1 alpha as well as TXB2 and low levels of PGD2 were noted. In addition, LC tissue from cigarette smokers demonstrated elevated levels of PGE2, 6KPGF1 alpha, and TXB2 when compared to current nonsmokers with LC (P less than 0.05 in all instances). Simultaneous comparison of PG production in matched LC and NL tissue from individual patients indicated increased biosynthesis of PGE2 and PGF2 alpha and low levels of PGD2 in LC compared to NL tissue (P less than 0.05 in all instances; paired, two-tailed, Student's t test). Individual comparison of PG biosynthesis according to LC histological cell type revealed that PGE2 and PGF2 alpha were consistently elevated in all four common primary LC histological cell types, the only exception being large cell undifferentiated carcinoma. Interestingly, this latter LC histological cell type presented a unique profile with lower levels of PGE2 and PGD2 in LC than in NL tissue (P less than 0.05 in both instances). In addition, the biosynthesis of all 5 PGs studied was consistently higher in primary than metastatic adenocarcinomas of the lung (P less than 0.05 in all instances). No differences were observed in NL and LC tissue for the major LC histological cell types when PGD2, TXB2, or 6KPGF1 alpha biosyntheses were compared. These findings indicate that the profiles of PG biosynthesis in LC and NL tissue from individual patients may differ substantially. These differences may reflect, in part, contributions to the PG biosynthetic profile unique to malignant cells.

Arachidonic Acid↗
PubMed1988

Early peak of creatine kinase-MB in acute myocardial infarction with a nondiagnostic electrocardiogram.

This study compared the time from the onset of symptoms to the peak of the creatine kinase-myocardial band (CK-MB) in 34 consecutive patients with acute myocardial infarction. Patients were separated into two groups: group 1 (n = 21) had diagnostic (greater than or equal to 0.1 mV) ST segment elevation on the initial ECG, and group 2 (n = 13) did not have diagnostic ST segment elevation on the initial ECG. In group 1 the time to the peak CK-MB was 16.2 +/- 50 hours vs 10.0 +/- 2.0 hours for group 2 (p = 0.0001). Peak CK-MB was 331 +/- 276 IU/L in group 1 vs 81 +/- 54 IU/L in group 2 (p less than 0.005). In group 1 there were 16 patients who subsequently had a Q wave myocardial infarction as opposed to one patient in group 2 (p = 0.0001). Patients who do not have diagnostic ST segment elevation on the initial ECG have an early but low peak of CK-MB and typically have a non-Q wave infarction. These findings are consistent with early spontaneous restoration of blood flow during the infarction process in these patients. This early restoration of blood flow may provide the substrate for the high incidence of recurrent ischemic events noted in patients with non-Q wave myocardial infarction.

Aged↗
PubMed1988

Isolation and characterization of chromosomal proteins from the mosquito Anopheles albimanus Weidemann.

1. Nuclei were isolated from adult anopheline mosquitoes and fractionated into nucleolar chromatin, nucleoplasmic chromatin and ribonucleoprotein particles by sucrose density gradients. 2. Histones and nonhistone proteins were selectively dissociated from chromatin by treatment with sodium chloride, urea and guanidine HC1. 3. A special class of nonhistone proteins (tight proteins) were extracted from chromatin with Na4P2O7. 4. The electrophoretic properties of the histones, nonhistone proteins and ribonucleoprotein particles were examined by isoelectric focusing and SDS multiphase polyacrylamide gel electrophoresis. 5. By contrast to the histones, the nonhistone proteins displayed considerable heterogeneity. 6. Possible functional implications of the chromosomal proteins are discussed.

Animals↗