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Biomedical subjects

D B Smith

Publications and source records attributed to D B Smith.

At least 217 records · Page 12Linked to original sources
PubMed1986

Accuracy of piezoelectric accelerometers measuring displacement of a spinal adjusting instrument.

The accuracy and reproducibility of an electronic system to measure the displacement of a spring-loaded chiropractic adjusting instrument was examined. The electronic system included a piezoelectric force transducer, piezoelectric accelerometer transducers and a digital oscilloscope. Accuracy was studied by comparing electronic measurements with the expansion allowed by the mechanically limiting expansion-control knob of the instrument. The results suggested improvements for future accuracy verification checks and detected accuracy within about 10% of the expansion of the commonly used expansion-control-knob revolutions. Preliminary experiments are presented to show application of the system to studies on thrusts into the spine. The impedance-head-equipped spring-loaded Activator chiropractic adjusting instrument had a low velocity when used on the patient and appeared to cause bone movement and a measurable EMG response.

Animals↗
PubMed1985

Comparison of carbamazepine, phenobarbital, phenytoin, and primidone in partial and secondarily generalized tonic-clonic seizures.

We conducted a 10-center, double-blind trial to compare the efficacy and toxicity of four antiepileptic drugs in the treatment of partial and secondarily generalized tonic-clonic seizures in 622 adults. Patients were randomly assigned to treatment with carbamazepine, phenobarbital, phenytoin, or primidone and were followed for two years or until the drug failed to control seizures or caused unacceptable side effects. Overall treatment success was highest with carbamazepine or phenytoin, intermediate with phenobarbital, and lowest with primidone (P less than 0.002). Differences in failure rates of the drugs were explained primarily by the fact that primidone caused more intolerable acute toxic effects, such as nausea, vomiting, dizziness, and sedation. Decreased libido and impotence were more common in patients given primidone. Phenytoin caused more dysmorphic effects and hypersensitivity. Control of tonic-clonic seizures did not differ significantly with the various drugs. Carbamazepine provided complete control of partial seizures more often than primidone or phenobarbital (P less than 0.03). Overall, carbamazepine and phenytoin are recommended drugs of first choice for single-drug therapy of adults with partial or generalized tonic-clonic seizures or with both.

Adolescent↗
PubMed1985

Regulated production of an influenza virus spliced mRNA mediated by virus-specific products.

The influenza virus NS2 mRNA is generated through processing by cellular enzymes of a transcript (the NS1 mRNA) of virion RNA segment 8. Production of this mRNA is altered in cells infected with a mutant of influenza A (fowl plague) virus. The proportion of segment 8 transcripts which accumulated in a spliced form was found to be considerably lower in mutant virus-infected cells than in cells infected with wild-type virus, and the amplification in production of NS2 mRNA relative to that of the NS1 mRNA, which normally occurs during infection with wild-type virus, was not observed with the mutant. The NS1 mRNA specified by the mutant virus has unaltered splice recognition sites and was apparently processed normally during a mixed infection with a strain of virus which is wild-type for production of NS2 mRNA. These results suggest that the production of NS2 mRNA is regulated by virus-specific products; these products may act by increasing the efficiency of splicing of NS1 mRNA.

Animals↗
PubMed1985

A Chinese hamster ovary cell mutant resistant to aphidicolin.

A triple (aphr ara-Ar and araCr) mutant (AP7) of Chinese hamster ovary cells resistant to DNA polymerase inhibitors is described. The aphidicolin-resistance of the mutant was stable and inherited as a dominant genetic trait. The DNA polymerase alpha from the wild type (aphs) and the mutant (aphr) cells differed in their elution profiles on DEAE-cellulose chromatography and in their molecular weights which were 192,000 for the wild type (CHO-K-1, AC6a) and 165,000 for the mutant (AP7) enzymes.

Animals↗
PubMed1985

Three months treatment with chemotherapy and radiotherapy for small cell lung cancer.

Fifty-five patients with inoperable but limited stage small cell carcinoma of the bronchus and a further 15 patients with contra lateral neck nodes, pleural effusions and marrow involvement were entered into the study and treated. The 3 month treatment regimen comprised 3 courses of etoposide with cyclophosphamide at 2.5 gm-2 followed by methotrexate and radiotherapy, no maintenance treatment was given. The complete response rate in the total patient group was 54% and the partial response rate 21%. The median survival was 11 months for the 70 patients, 15 months for the complete responders, and those patients with a bronchoscopically confirmed complete response survived significantly longer. There was no significant difference between the patients with strictly limited stage disease and those in the broader category. Eight patients are tumour free and alive one year or more after the end of treatment. The median followup is 17 months. Twenty-four patients were delayed 1-2 weeks during treatment because of chemotherapy induced toxicity. Six patients died probably of infection associated with leucopaenia. The majority of the patients' Karnofsky performance improved with the treatment as did their breathlessness assessed on a respiratory score. The short intensive chemotherapy regimen of 3 months produced similar results to those following more prolonged treatment regimens.

Adult↗
PubMed1985

The cross-linking of human Met-hemoglobin with [14C]dimethyl adipimidate.

Met-hemoglobin, cross-linked with [14C]dimethyladipimidate (cross-linking span 9 A; 1 A = 0.1 nm), yields four distinct molecular weight products (monomer, dimer, trimer, and tetramer) as observed on sodium dodecyl sulfate - polyacrylamide gels. The dimer species was purified to homogeneity by gel filtration. It was proteolytically degraded using a combination of Staphylococcus aureus V8 protease, pepsin, trypsin, and chymotrypsin. The resultant peptides were fractionated using gel filtration and ion-exchange chromatography methods. Two cross-links were unambiguously identified: (i) alpha 1Lys7-alpha 1Lys11 and (ii) beta 1Lys82-beta 2Lys82. The identified cross-links correlated well with the known structure of hemoglobin. However, attempts to isolate and identify a greater number of cross-linked peptides were unsuccessful owing to the complexity of the peptide mixtures. The complexity was a direct result of the chemical modification of the hemoglobin molecule. Therefore, attempts to employ chemical cross-linking as a means of examining sites of protomer contact within large oligomeric proteins should be approached with caution.

Cross-Linking Reagents↗
PubMed1985

A reliable method for localizing deep intracranial sources of the EEG.

We have demonstrated the reliability of a noninvasive method for successfully localizing the intracranial origin of the EEG. The dipole localization method (DLM) is a computer-assisted, mathematical method based on electrical field theory and is similar to localization methods currently used by electrocardiologists. In 12 patients with intractable epilepsy who were being evaluated for surgery, a known current source was introduced between two adjacent depth electrodes. Using scalp-recorded EEG only, DLM accurately and reliably localized the source to within 2 cm of the known origin in all instances where a discrete source was present. We conclude that DLM is a valid and reliable noninvasive method for localizing the intracranial source of some scalp-recorded EEG potentials, and that in some patients, use of this method may obviate the need for depth electrode implantation.

Adult↗
PubMed1985

Cerebral amyloid angiopathy presenting as transient ischemic attacks. Case report.

Cerebral amyloid angiography can cause ischemic stroke and transient ischemic attacks (TIA's), as illustrated by this case report and literature review. It is possible that the use of anticoagulant or platelet-antiaggregant drugs in elderly patients with TIA's but no angiographic abnormalities may increase the risk of hemorrhage from unsuspected amyloid angiopathy.

Aged↗
PubMed1985

Carcinomatous meningitis associated with infiltrating lobular carcinoma of the breast.

The records of 365 patients with advanced carcinoma of the breast were examined to identify those with CNS involvement. Nineteen (5.2%) developed parenchymal cerebral deposits and 10 (2.7%) developed meningeal infiltration during the course of their disease. Parenchymal cerebral deposits were almost exclusively associated with infiltrating duct carcinoma (95%) and meningeal infiltration (carcinomatous meningitis) was almost exclusively associated with infiltrating lobular carcinoma. Meningeal infiltration occurred late in the course of advanced disease and was associated with diffuse involvement of the bone marrow and abdominal structures.

Adult↗
PubMed1984

Effect of chronic phenobarbital treatment on folates and one-carbon enzymes in the rat.

Chronic oral phenobarbital treatment (50 mg/kg every 12 hr for 8 weeks), which was nontoxic and continuously protective against seizures in rats, significantly decreased folate concentration in liver (29%) but not in brain or plasma. The apparent activity of 5,10-methylenetetrahydrofolate reductase (MTR) in liver decreased with initiation of treatment but then increased with a significant correlation to the length of treatment. Phenobarbital also stimulated the activity of this enzyme slightly in vitro. Methionine adenosyltransferase (MAT) activity was inhibited by high concentrations of phenobarbital in vitro but was not affected in vivo. No significant effects of phenobarbital on the activities of serine hydroxymethyltransferase (SHMT) or 5-methyltetrahydrofolate:homocysteine methyltransferase (MHMT) were observed either in vivo or in vitro.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed1984

Hemoglobin S levels in sickle cell trait individuals.

Changes in Department of Defense regulations now permit persons with sickle cell trait to serve in all service branches. However, for purposes of the regulation, sickle cell trait is defined as 41% or less S hemoglobin. Our screening experience, based on 397 individuals with sickle cell trait, with quantitative scan of cellulose acetate electrophoretic sheets, indicates that 20-40% (depending on definition of terms) of individuals with sickle cell trait would be excluded by this criterion.

Anemia, Sickle Cell↗
PubMed1984

Massive bleeding from an ileal conduit caput medusae.

A caput medusae developing around an ileal conduit stoma heralded the onset of portal hypertension and recurrent episodes of massive stomal bleeding in a patient with liver cirrhosis. A review of the literature suggests that conservative local measures remain the treatment of choice in the high risk cirrhotic patient.

Aged↗
PubMed1984

Sudden behavioral change. Guide to initial evaluation.

Described is an approach to understanding sudden behavioral change that is based on a simplified conceptual model of the functional anatomy of the CNS. The model explores the behavioral correlates of three interrelated CNS functional axes: vertical, lateral, and horizontal.

Attention↗