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Biomedical subjects

M D Smith

Publications and source records attributed to M D Smith.

At least 469 records · Page 26Linked to original sources
PubMed1986

Protoplast transformation in coryneform bacteria and introduction of an alpha-amylase gene from Bacillus amyloliquefaciens into Brevibacterium lactofermentum.

The goal of this study was to investigate the likelihood of developing useful transformation systems for coryneform bacteria. Two species of coryneform bacteria, Brevibacterium lactofermentum and Corynebacterium lilium, were transformed with chimeras constructed from pUB110 and a cryptic coryneform plasmid (pGX1901). C. lilium protoplasts were also efficiently transfected with phage CS1 DNA. High transformation and transfection frequencies were obtained after only 2 min of lysozyme treatment of lysozyme-sensitive mutants. A series of experiments was also conducted to determine whether DNA from other species of important industrial microbes from the genus Bacillus could be expressed in coryneform bacteria. Evidence of restriction of Bacillus subtilis DNA by B. lactofermentum was observed but could be overcome. A Bacillus amyloliquefaciens alpha-amylase gene (amyEBamP) was subcloned onto a plasmid able to replicate in B. lactofermentum. B. lactofermentum transformants for this plasmid expressed amylase activity and produced material cross-reactive to amylase antibody.

Bacillus↗
PubMed1986

A DNA damage-responsive Drosophila melanogaster gene is also induced by heat shock.

A gene isolated by screening Drosophila melanogaster tissue culture cells for DNA damage regulation was also found to be regulated by heat shock. After UV irradiation or heat shock, induction is at the transcriptional level and results in the accumulation of a 1.0-kilobase polyadenylated transcript. The restriction map of the clone bears no resemblance to the known heat shock genes, which are shown to be uninduced by UV irradiation.

Animals↗
PubMed1986

Comparative accuracy of two-dimensional echocardiography and Doppler pressure half-time methods in assessing severity of mitral stenosis in patients with and without prior commissurotomy.

This study was undertaken to compare the accuracies of the two-dimensional echocardiographic (2DE) and Doppler pressure half-time methods for the noninvasive estimation of cardiac catheterization measurements of mitral valve area in patients with pure mitral stenosis both with and without a previous commissurotomy. Data were retrospectively obtained from 74 consecutive patients who underwent cardiac catheterization within a 30 month period for evaluation of mitral stenosis, and who had two-dimensional echocardiograms performed before catheterization. Six patients (8.1%) had technically inadequate 2DE images and their data were excluded from analysis. Two of these patients had undergone commissurotomy, while the remaining four had not. Continuous-wave Doppler echocardiographic examinations were attempted in 45 patients and adequate measurements of pressure half-times were obtained in all patients studied. Mitral valve area by two-dimensional echocardiography was measured as the planimetered area along the inner border of the smallest mitral orifice visualized during short-axis scanning, while pressure half-time was calculated as the interval between the peak transmitral velocity and velocity/square root 2 as measured from the envelope of the Doppler spectral signal. Calculations from catheterization represented the minimal valve area at rest as derived from the Gorlin formula with the use of pressure gradients and thermodilution measurements of cardiac output. Thirty-seven of the patients had had a previous mitral commissurotomy a mean of 11.2 +/- 5.4 years before, while the remaining 37 patients were previously unoperated. Mean valve area as determined at catheterization for the total group of patients ranged from 0.37 to 2.30 cm2 (mean = 1.08 +/- 0.42 cm2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Hormonal regulation of collagen synthesis in a clonal rat osteosarcoma cell line.

Collagen synthesis in rat osteosarcoma cell line 17/2 (ROS 17/2) was assessed by measuring the incorporation of [3H]proline into collagenase-digestible protein and the formation of [3H]hydroxyproline. PTH and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] inhibited collagen synthesis in ROS 17/2 cells in a time- and dose-dependent manner. PTH reduced collagen synthesis after a 3-h incubation, whereas the effect of 1,25-(OH)2D3 was somewhat slower. Maximal and half-maximal inhibition of collagen synthesis occurred at approximately 1 and 0.1 nM of each hormone, respectively. At confluency, ROS 17/2 cells synthesized 96% type I and 4% type III collagen. PTH reduced the synthesis of type I, but not type III, collagen. PTH and 1,25-(OH)2D3 also reduced procollagen mRNA levels, as determined by a dot blot hybridization assay. Thus, ROS 17/2 cells are a convenient model system for studying the hormonal regulation of collagen metabolism and gene expression in a cloned cell line with the osteoblastic phenotype.

Animals↗
PubMed1986

Detection of aortic insufficiency by standard echocardiography, pulsed Doppler echocardiography, and auscultation. A comparison of accuracies.

To determine the relative sensitivity and specificity of noninvasive methods for detecting aortic insufficiency, we compared the accuracy of auscultation, echocardiography, and pulsed Doppler echocardiography in detecting aortic insufficiency in 106 patients in whom the presence or absence of the lesion was shown by supravalvular aortography. The sensitivity and specificity for the diagnosis of aortic regurgitation was 96% and 96% for pulsed Doppler echocardiography, 73% and 92% for auscultation, 43% and 91% for two-dimensional echocardiography, 46% and 81% for anterior mitral leaflet flutter, and 9% and 96% for ventricular septal flutter, respectively. Auscultation was more sensitive than either M-mode or two-dimensional echocardiography in the diagnosis of aortic insufficiency (p less than 0.01). Pulsed Doppler echocardiography was significantly more sensitive than auscultation (p less than 0.0001) and was positive in 19 patients in whom no murmur was found. Thus, pulsed Doppler echocardiography is the optimal noninvasive marker for aortic insufficiency.

Adolescent↗
PubMed1986

Piroxicam versus naproxen in the treatment of painful shoulder.

A double-blind, parallel trial of 40 patients with chronic shoulder pain was carried out to compare alleviation of pain and improvement in mobility after treatment with 20 mg piroxicam each morning or 250 mg naproxen twice daily. During the 3-week study, patients also underwent conservative treatment of therapeutic exercise. Piroxicam was better than naproxen at relieving pain at night, but time, rather than a drug effect, seemed responsible for the improvement in shoulder abduction. No difference between the drugs was demonstrated regarding their effect on pain on active movement of the shoulder and external rotation.

Double-Blind Method↗
PubMed1986

Use of the Hickman catheter for jejunal feedings in children.

A simple, safe method for creating a long term jejunal feeding route using the standard Hickman catheter is described herein. The positive results in pediatric patients suggest that this method would be suitable in selected adult instances.

Abdominal Muscles↗
PubMed1986

Thrombolytic therapy in heparin-associated thrombocytopenia with thrombosis.

Use of urokinase to treat heparin-associated thrombocytopenia and thrombosis in one patient is described, and various treatments proposed for this syndrome are discussed. A 56-year-old man received an intravenous bolus dose of heparin sodium at his local hospital and was transferred to another institution for treatment of suspected pulmonary embolism; he had received heparin two weeks earlier during coronary angiography. The patient's platelet count was reported to be normal before heparin administration. When embolism was confirmed, heparin was discontinued and streptokinase was given for 24 hours. Heparin infusion was then restarted at 1000 units/hr and continued for four days. Platelet count on admission to the second hospital was 47,000/cu mm; 12 hours later it was 19,000/cu mm, and it remained low despite platelet transfusions. Five days after admission, deep-vein thrombosis developed in the left leg. Heparin was discontinued and urokinase and warfarin were started. Urokinase was infused at 320,000 IU/hr for 12 hours and continued at dosages of 160,000-320,000 IU/hr for a total of 40 hours. The initial warfarin sodium dose was 15 mg, followed by a dosage of 10 mg/day. Symptoms of deep-vein thrombosis improved within 12 hours and platelet count increased after heparin was discontinued. If it is recognized early enough, heparin-associated thrombocytopenia can be reversed by discontinuation of heparin. Transfusions of platelets are of little benefit. Dipyridamole, cyclo-oxygenase inhibitors such as aspirin, and protamine sulfate may be useful. Long term anticoagulation with warfarin is recommended to prevent recurrent thrombosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗
PubMed1985

Muscarinic acetylcholine receptors in chick heart: influence of heat and N-ethylmaleimide on receptor conformations and interactions with guanine nucleotide-dependent regulatory proteins.

Several conformations of muscarinic acetylcholine receptors in chick heart are revealed by the energetics of agonist binding. Heating cardiac membranes at 50 degrees C for 5 min decreased agonist affinity, steepened agonist binding curves and eliminated receptor sensitivity to guanine nucleotides. N-ethylmaleimide (NEM) steepened agonist binding curves and eliminated receptor sensitivity to guanine nucleotides without decreasing agonist binding affinity. NEM prevented and reversed the effect of heat on agonist affinity. Pirenzepine and N-methylscopolamine binding were unaffected by either treatment. NEM and heat stabilize muscarinic receptors in conformations unrelated to those associated with naturally occurring receptor populations.

Animals↗
PubMed1985

Teaching life skills to adults disabled by autism.

The acquisition of life skills is a high priority for adults disabled by autism who are living in community-based residential programs. A training program was implemented and evaluated that consisted of analyzing life skills into component steps and providing increasing levels of assistance according to a predetermined schedule. Five adults who were severely disabled by autism and who lived in group homes in the community served as participants. All five adults showed progress in targeted life skills, and four of the five achieved independence on their targeted skills. The usefulness of this training model in community-based residential programs is discussed.

Activities of Daily Living↗
PubMed1985

Diagnosis of depression in patients with end-stage renal disease. Comparative analysis.

To evaluate the variability in the diagnosis of depression in patients receiving maintenance therapy for end-stage renal disease, a study of 60 randomly selected patients was conducted. Three representative depression assessment methods were employed concurrently in the evaluation of each patient: (1) a structured psychiatric interview based on the diagnostic criteria of the American Psychiatric Association (DSM-III); (2) the Beck Depression Inventory; and (3) the Multiple Affect Adjective Check List. Among the 60 patients, 47 percent were classified as depressed by the Beck Depression Inventory, whereas 17 percent and 5 percent were determined to be depressed according to the Multiple Affect Adjective Check List and DSM-III criteria, respectively. The data demonstrated these differences to be dependent on the overlap between the symptoms of uremia and depression, as well as on the duration of those symptoms. This study also suggests that death wish, suicidal intention, and other psychologic symptoms should receive particular attention in the clinical assessment of depression in patients with end-stage renal disease.

Adult↗
PubMed1985

Geographic access to health care services: the case of maintenance hemodialysis.

A longitudinal study of the system for delivering maintenance hemodialysis services in St Louis, Missouri was conducted to determine the significance of geographic access in the selection and continued utilization of a treatment facility. Historically, center hemodialysis patients in this metropolitan area received care at four centrally located facilities. In 1981, two new, independent facilities were constructed; a satellite of an existing unit was opened in 1983. The data obtained in this study demonstrated that end-stage renal disease (ESRD) patients generally did not change their mode of maintenance therapy, their treatment facility, or the location of their personal residence. When such changes occurred, they were rarely precipitated by a desire to reduce travel time to treatment. Furthermore, the opportunity to improve geographic access by transferring to a closer unit was perceived by patients to be viable only if they could retain their physician. It was concluded, therefore, that travel time to treatment is a relatively unimportant aspect of the chronic care of center hemodialysis patients in a metropolitan area.

Adult↗
PubMed1985

Does social support determine the treatment setting for hemodialysis patients?

The availability of an adequate system of social support has been suggested to be significant in determining whether an end-stage renal disease (ESRD) patient is dialyzed in a center or at home. To evaluate this hypothesis more completely, we conducted a study of social support among 257 home and center hemodialysis patients receiving maintenance therapy at four facilities in a midwestern, metropolitan area. A statistically significant difference, chi 2(3) = 14.031, P = 0.0029, was observed in the percentage of patients with social support available to them across the four facilities. The distribution of patients between home and center hemodialysis at the facilities also differed significantly, chi 2(3) = 14.919, P = 0.0019. An adequate social support system was present among 96.4% of the 55 home hemodialysis patients and 85.6% of the 202 center hemodialysis patients, a difference that was statistically significant, chi 2(1) = 4.684, P = 0.0305. However, a more detailed analysis of these findings revealed that the presence of social support was not significant, chi 2(1) = 1.080, P = 0.2995, in determining whether and ESRD patient was dialyzed at home or in a center after accounting for the facility differences. The facility differences remained significant in determining the setting of hemodialysis even after correcting for social support, chi 2(3) = 10.740, P = 0.0132. We concluded, therefore, that the attitudes of clinical staff toward home and center hemodialysis and the willingness of staff to develop those resources that facilitate a specific treatment setting are the principal elements in the therapy selection process.

Adult↗
PubMed1985

Correlation of continuous wave Doppler velocities with cardiac catheterization gradients: an experimental model of aortic stenosis.

The purpose of this study was to use a canine preparation of experimental aortic stenosis to compare estimates of pressure gradient derived from continuous wave Doppler ultrasound with gradients measured directly by catheterization. Aortic stenosis was created in six mongrel dogs by placing an elastic band around the aorta. Eighty-eight different pressure gradients, ranging from 5 to 160 mm Hg, were produced by variable tightening of the aortic band. Pressure gradients were measured by micromanometer-tipped catheters placed in the left ventricle and aorta. Doppler spectral signals were simultaneously obtained using a 2.0 MHz nonimaging transducer placed directly on the surface of the ascending aorta. Doppler and pressure recordings were analyzed using a custom-designed software program to measure maximal instantaneous, mean and peak to peak gradients, as well as ejection and acceleration times. Maximal instantaneous Doppler gradient showed an excellent linear correlation with maximal instantaneous catheterization gradient (r = 0.98, SEE = 5.3 mm Hg). The correlation of Doppler-estimated maximal gradient to peak to peak catheterization gradient was also linear (r = 0.97, SEE = 6.2 mm Hg) but resulted in a systematic overestimation of pressure drop (mean overestimation = 9.0 mm Hg). Measurement of the Doppler gradient at mid-systole resulted in a more accurate correlation with the peak to peak catheterization gradient (r = 0.98, SEE = 6.1 mm Hg) and eliminated the problem of overestimation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Transformation and fusion of Streptococcus faecalis protoplasts.

Nonconjugative plasmids were transferred by protoplast fusion among Streptococcus faecalis strains and from Streptococcus sanguis to S. faecalis. S. faecalis protoplasts were also transformed with several different plasmids, including the Tn917 delivery vehicle pTV1. Transformation was reproducible, but low in frequency (10(-6) transformants per viable protoplast). A new shuttle vector (pAM610), able to replicate in Escherichia coli and S. faecalis, was constructed and transformed into S. faecalis protoplasts. pAM610 was mobilized by the conjugative plasmid pAM beta 1 in matings among S. faecalis strains and from S. sanguis to S. faecalis. Chimeric derivatives of pAM610 were also transformed into S. faecalis.

Culture Media↗
PubMed1985

The effect of tiaprofenic acid on blood pressure control in treated hypertensive patients.

Eleven patients with osteoarthritis and mild hypertension completed an 8-week, double-blind crossover study in which 200 mg tiaprofenic acid 3-times daily or placebo were substituted for their normal non-steroidal anti-inflammatory therapy. Systolic blood pressure was significantly higher on tiaprofenic acid therapy than on placebo and plasma renin activity was significantly lower on active treatment. No significant changes were seen in biochemical parameters, though the weight of the patient was also higher on tiaprofenic acid than on placebo. Duration of morning stiffness was also lower on tiaprofenic acid than on placebo. Blood pressure on tiaprofenic acid was not different from baseline readings on other non-steroidal anti-inflammatory drug therapy. This study suggests that tiaprofenic acid, like other non-steroidal anti-inflammatory agents, may interfere with blood pressure control in treated hypertensive patients.

Aged↗
PubMed1985

Characterization of the effect of insulin on collagen synthesis in fetal rat bone.

We characterized the effect of insulin on collagen synthesis in 21-day-old fetal rat calvaria maintained in organ culture. All experiments were done in the presence of 100 mg/dl glucose and 3 mM phosphate, which were found to be optimal concentrations for insulin responsiveness. All concentrations of insulin tested (1 nM to 1 microM) increased the percentage of collagen being synthesized in the central bone, whereas only high concentrations of hormone (100 nM to 1 microM) increased the percentage of collagen being synthesized in periosteum. Insulin at 3 nM increased the labeling of type I collagen in the central bone, but did not alter the labeling of type I or III collagen in the periosteum. Proinsulin was approximately 10-100 times less effective than insulin in stimulating collagen synthesis, whereas porcine relaxin and C-peptide were ineffective. Insulin did not enhance the deposition of newly synthesized collagen in the bone by a mechanism that involved decreasing the degradation of collagen. To determine whether insulin enhanced collagen synthesis by increasing the replication of collagen-synthesizing cells, we tested the effect of insulin in the presence of hydroxyurea, a DNA synthesis inhibitor. Hydroxyurea at 1 mM had little effect on collagen synthesis in control cultures or those treated with 1 or 10 nM insulin. However, hydroxyurea blunted the stimulation of collagen synthesis that occurred at higher concentrations of insulin. These experiments suggest that insulin at physiological levels appears to increase bone collagen synthesis by a direct effect on the osteoblast, whereas insulin at high concentrations has an additional action to increase the replication of collagen-synthesizing cells.

Animals↗