PubMed Health⌕ Search

Biomedical subjects

T H Smith

Publications and source records attributed to T H Smith.

At least 19 recordsLinked to original sources
PubMed1992

Looking back and looking forward.

'Forty years back and forty years on' was the title of the address given by Francis Manfield at the annual meeting of the RCS of England in December 1970. Francis, twice president of the Middx & Herts Branch, which this year celebrates its first 40 years, started in practice in 1930, so he was well qualified to look back over those 40 years. The aspects of change in dentistry, 1930-1970, make arresting reading more than 20 years later. His predictions for the future are equally interesting.

Dental Instruments↗
PubMed1992

Distinct myogenic programs of embryonic and fetal mouse muscle cells: expression of the perinatal myosin heavy chain isoform in vitro.

Early embryonic and late fetal mouse myogenic cells showed distinct patterns of perinatal myosin heavy chain (MHC) isoform expression upon differentiation in vitro. In cultures of somite or limb muscle cells isolated from Day 9 to Day 12 embryos, differentiated cells that expressed perinatal MHC were rare and perinatal MHC was not detectable by immunoblotting. In cultures of limb muscle cells isolated from Day 13 to Day 18 fetuses, in contrast, the perinatal MHC isoform was easily detected and was expressed in a substantial percentage of myocytes and myotubes. Analyses of clonally derived muscle colonies and cytosine arabinoside-treated fetal muscle cell cultures suggested that different fetal muscle cell nuclei initiated perinatal MHC expression at different times. In both embryonic and fetal cell cultures, the embryonic MHC isoform was expressed by all differentiated cells examined. A small number of myotubes in fetal muscle cell cultures showed a mosaic distribution of MHC isoform accumulation in which the perinatal MHC isoform accumulated in a restricted region of the myotube near particular nuclei, whereas the embryonic MHC isoform accumulated throughout the myotube. Thus, the myogenic program of fetal, but not embryonic, mouse myogenic cells includes expression of the perinatal MHC isoform upon differentiation in culture.

Animals↗
PubMed1991

Wolf syndrome.

Since the initial description in 1965 of Wolf syndrome, or deletion of the short arm of chromosome number four, over one hundred cases have been reported. Much less, however, has been published on the radiologic findings in this disorder. We report a case with both typical and unusual features of the 4p- syndrome, including "bottle opener" deformity of the clavicles, and review the relevant literature.

Abnormalities, Multiple↗
PubMed1991

Seatbelt induced chance fracture in an infant. Case report and literature review.

Chance ("seat belt") fractures of the lumbar spine are extremely rare in the pediatric population and virtually unheard of in infants. We report a case of a 14 month old boy sustaining an isolated Chance fracture to L1 without associated spinal subluxation, dislocation, neurologic or visceral injury. He was being breast fed with his back beneath the passenger side shoulder harness when the vehicular front end collision causing his injury occurred. Thus, he may actually have sustained a hyperextension distraction or "Reverse Chance" fracture.

Accidents, Traffic↗
PubMed1990

Practice brochures and newsletters.

One of Tom's great gifts is his enthusiasm for writing practice newsletters for his patients that he personalizes to communicate his caring attitude towards them. But beneath all that is a tremendous amount of hard work, discipline and dedication that he puts into producing these newsletters. We think the results are worth the effort, and that is why we decided to feature this article.

Dentist-Patient Relations↗
PubMed1989

Imaging artifacts in mechanically driven ultrasound catheters.

Mechanically driven catheter tip echo systems presently operate with a flexible shaft. Rotation power from a proximally mounted motor is transferred via this shaft to the rotating echo tip element. In practice, the tip does not identically 'follow' the rotation of the motor due to low torsional rigidity of the shaft, which creates artifacts in the displayed cross-sectional image. In order to visualize curved arteries such as the coronary arteries, a compromise is necessary between the required low flexural rigidity and a high torsional rigidity. In this report the image artifacts of mechanically driven systems are presented that are related to catheter tip motion. The properties of a spiral drive-shaft and a solid drive-shaft have been compared for rotational speed of 1000 and 3000 revolutions per minute (rpm), and for straight as well as strongly curved catheters. By way of example, the periodic angle error varies from 25 degrees top-top in a straight catheter to 80 degrees top-top when the catheter is curved with R = 20 mm, using a spiral drive-shaft at 1000 rpm.

Angioplasty, Balloon↗
PubMed1979

Structural biochemistry XIII: Synthesis of luteinizing hormone-releasing hormone modification [Trp8]-LH-RH.

A fragment condensation method was utilized for synthesis of the Trp8-substituted luteinizing hormone-releasing hormone (LH-RH). tert-Butoxycarbonyl protection was employed for the alpha-amino positions, and benzyl protection was used for the phenol group of Tyr and the imidazole nitrogen of His. Peptide bond-forming reactions were performed using N-hydroxysuccinimide (for Trp), dicyclohexylcarbodiimide-1-hydroxybenzotriazole, 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide hydrochloride, or mixed carbonic anhydride methods. Biological evaluation of [Trp8]-LH-RH indicated no luteinizing hormone-releasing activity or inhibition of luteinizing hormone release over the dose ranges studied.

Animals↗
PubMed1979

Postradiation renovascular hypertension.

Radiation injury to arteries can represent a significant complication of therapeutic irradiation, even when the dosage used has not been excessive as judged by approved protocols. Children in whom therapeutic abdominal irradiation has been used should be monitored indefinitely for the development of hypertension. The presence of hypertension in such children with normal blood urea nitrogen (BUN) and creatinine, and without proteinuria, should prompt investigation for a renovascular lesion. Standard bypass procedures are usually effective, although the long-term success may be compromised by continuing changes in affected vessels.

Adolescent↗
PubMed1979

Synthesis of daunorubicin analogues with novel 9-acyl substituents.

Synthetic approaches to anthracyclines bearing novel 9-acyl substituents were investigated. Reaction of the lithium enolate of N-(trifluoroacetyl)daunorubicin (9) with methyl iodide in tetrahydrofuran afforded only the 9-propionyl derivative 10 in high yield. Reaction of 10 under identical conditions cleanly afforded the 9-isobutyryl derivative 11. Extension of this procedure to other alkylating agents (ethyl iodide, benzyl bromide, and heptyl iodide) required hexamethylphosphoramide as cosolvent and afforded mixtures of mono- and dialkylated products as well as recovered 9. The amino group was deblocked with NaOH in aqueous tetrahydrofuran, except in the case of the dibenzyl derivative 13 which was inert under these conditions. The 9-formyl analogue 23 was prepared via NaIO4 cleavage of 13-dihydroadriamycin (21). Antitumor evaluation against P388 leukemia in mice showed 23 to have activity comparable to the parent compounds, while the C-alkylated analogues were less active.

Animals↗
PubMed1979

Adriamycin analogues. 3. Synthesis of N-alkylated anthracyclines with enhanced efficacy and reduced cardiotoxicity.

Reaction of daunorubicin (1) and adriamycin (2) with aldehydes and ketones in the presence of NaCNBH3 afforded N-alkyl- and N,N-dialkylanthracyclines along with their 13-dihydro derivatives. Product ratios depended upon the nature of the carbonyl reagent and the starting drug. The majority of these analogues retained in vivo antitumor activity comparable to 1 and 2. However, unlike the parent compounds, which inhibit DNA and RNA synthesis at comparable concentrations, several of these analogues inhibit RNA synthesis at markedly lower concentrations than required to inhibit DNA synthesis. In addition, in some cases the ability to bind to DNA in vitro was reduced while antitumor activity was retained. N,N-Dibenzyldaunorubicin was especially notable for increased efficacy (T/C 259, qd 1--9) against P388 leukemia in mice, despite reduction of DNA binding in vitro. It showed almost complete loss of mutagenicity vs S. typhimurium (Ames test) and it was tenfold less cardiotoxic by electrocardiographic measurements (Zbinden test) in the rat.

Alkylation↗
PubMed1979

7-(Aminoethyl) ether and thioether of daunomycinone.

One-step treatment of daunomycinone with excess 2-aminoethanethiol and 2-aminoethanol in trifluoroacetic acid afforded at C-7 the thioether (77% yield) and ether (30% after recycling), respectively. Stereoselectivity for the natural 7S over the 7R configuration was greater for the ether (97:3) than for the thioether (2.5:1). Esterification of daunomycin at C-7 with beta-alanine was accomplished through the mixed anhydride of Z(OMe)-beta-alanine. Preliminary biological tests suggests that the antitumor and DNA interactive properties of the anthracyclines can be retained in such structures.

Animals↗
PubMed1978

Adriamycin analogues. 2. Synthesis of 13-deoxyanthracyclines.

The syntheses of several 13-deoxyanthracyclines are described. Koenigs-Knorr condensation of epsilon-rhodomycinone (12) with the protected daunosaminyl chloride 15 afforded 14 after deprotection. Efforts to decarbomethoxylate 12, as well as attempts to selectively deoxygenate the 13 position of daunomycinone and adriamycinone, were unsuccessful as approaches to 13-deoxyanthracyclines. However, reaction of the readily available tosylhydrazones 4 and 5, of daunorubicin and adriamycin with NaCNBH3 in acidic MeOH, afforded the 13-deoxy analogues 6 and 7 in satisfactory yield. These compounds retained antitumor activity, being comparable to the parent compounds in both efficacy and potency in the P-388 mouse leukemia screen. The epsilon-rhodomycinone glycoside 14 was less active than 6 and 7.

Animals↗
PubMed1978

Cystic retroperitoneal lymphangioma in infants and children.

Retroperitoneal lymphangiomas are uncommon benign tumors usually presenting in early life. They may cause significant pressure on adjacent structures, most often with superior and medial displacement of the kidney and medial deviation of the ureter. Relative radiolucency on total body opacification during excretory urography, and features of a cystic structure on ultrasonography and computed tomography should further suggest the possibility of a retroperitoneal lymphangioma. Vascular stretching and displacement without neovascularity on angiography and contrast entry into the cysts on lower extremity lymphography are additional features, but such procedures are usually unnecessary.

Child, Preschool↗
PubMed1977

The Lenz-Majewski hyperostotic dwarfism. A syndrome of multiple congenital anomalies, mental retardation, and progressive skeletal sclerosis.

A distinct syndrome is delineated on the basis of two previously reported and one newly described case. The syndrome combines multiple congenital anomalies with a progressive skeletal dysplasia-dysostosis, The gradual evolution of the skeletal disorder is demonstrated in the present patient. It will now be possible to diagnose this syndrome at birth.

Abnormalities, Multiple↗