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Biomedical subjects

T H Smith

Publications and source records attributed to T H Smith.

At least 37 records · Page 2Linked to original sources
PubMed1993

Cellular and molecular diversity in skeletal muscle development: news from in vitro and in vivo.

Skeletal muscle formation is studied in vitro with myogenic cell lines and primary muscle cell cultures, and in vivo with embryos of several species. We review several of the notable advances obtained from studies of cultured cells, including the recognition of myoblast diversity, isolation of the MyoD family of muscle regulatory factors, and identification of promoter elements required for muscle-specific gene expression. These studies have led to the ideas that myoblast diversity underlies the formation of the multiple types of fast and slow muscle fibers, and that myogenesis is controlled by a combination of ubiquitous and muscle-specific transcriptional regulators that may be different for each gene. We further review some unexpected results that have been obtained when ideas from work in culture have been tested in developing animals. The studies in vivo point to additional molecular and cellular mechanisms that regulate muscle formation in the animal.

Animals↗
PubMed1993

A unique pattern of expression of the four muscle regulatory factor proteins distinguishes somitic from embryonic, fetal and newborn mouse myogenic cells.

A unique pattern of expression of the four muscle regulatory factor (MRF) proteins was found to distinguish early somitic from embryonic, fetal and newborn limb myogenic cells in vitro. Expression of the myosin heavy chain (MHC), MyoD, myogenin, Myf-5, and MRF4 proteins was examined by immunocytochemistry in cultures of four distinct types of mouse myogenic cells: somitic (E8.5), embryonic (E11.5), fetal (E16.5) and newborn limb. In embryonic, fetal and newborn cultures, the MRF proteins were expressed in generally similar patterns: MyoD was the first MRF expressed; MyoD and myogenin were expressed by more cells than Myf-5 or MRF4; and each of the four MRFs was found both in cells that expressed MHC and in cells that did not express MHC. In cultures of somitic cells, in contrast, Myf-5 was expressed first and by more cells than MyoD or myogenin; MRF4 was not detected; and the MRFs were never found to be coexpressed with MHC in the same cell. Thus, some somitic cells had the unexpected ability to maintain MHC expression in the absence of detectable MRF protein expression. The different myogenic programs of embryonic, fetal and newborn myogenic cells are not, therefore, a simple result of qualitatively different MRF expression patterns, whereas myogenesis by somitic cells does include a unique pattern of MRF expression.

Animals↗
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↗
PubMed1988

Biochemical deficiencies of coenzyme Q10 in HIV-infection and exploratory treatment.

AIDS patients (2 groups) had a blood deficiency (p less than 0.001) of coenzyme Q10 vs. 2 control groups. AIDS patients had a greater deficiency (p less than 0.01) than ARC patients. ARC patients had a deficiency (p less than 0.05) vs. control. HIV-infected patients had a deficiency (p less than 0.05) vs. control. The deficiency of CoQ10 increased with the increased severity of the disease, i.e., from HIV positive (no symptoms) to ARC (constitutional symptoms, no opportunistic infection or tumor) to AIDS (HIV infection, opportunistic infection and/or tumor). This deficiency, a decade of data on CoQ10 on the immune system, on IgG levels, on hematological activity constituted the rationale for treatment with CoQ10 of 7 patients with AIDS or ARC. One was lost to follow-up; one expired after stopping CoQ10; 5 survived, were symptomatically improved with no opportunistic infection after 4-7 months. In spite of poor compliance of 5/7 patients, the treatment was very encouraging and at times even striking.

AIDS-Related Complex↗
PubMed1987

Bilateral posterior choanal atresia: a morphologic and histologic study, and computed tomographic correlation.

Bilateral posterior choanal atresia is an uncommon cause of respiratory obstruction in the newborn. Although the clinical syndrome and treatment options are well known, the abnormal histology has not been well described. Computed tomography (CT) is a useful tool in the radiologic diagnosis of choanal atresia, but has not been correlated with the histopathology. Two patients with CHARGE association (congenital heart defects, choanal atresia, retarded growth and development, hypogenitalism, and aural anomalies) and bilateral posterior choanal atresia were studied with CT. The atresia plates were removed at autopsy and sectioned in an axial plane for gross and microscopic study. The histopathology is described and correlated with the CT studies. These studies show that CT accurately defines the histopathologic abnormalities found in bilateral posterior choanal atresia.

Abnormalities, Multiple↗
PubMed1986

N-(2-hydroxyethyl)doxorubicin from hydrolysis of 3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin.

The susceptibility of 3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin to hydrolysis at pH 7, 4, and 2 has been compared with that of the typically stable morpholine analogue. At pH 7, 74% of the cyanomorpholine was unchanged after 24 h at room temperature, but at pH 2 only 10% remained. Products identified were aglycon (8%) and N-(2-hydroxyethyl)doxorubicin (7%). Most of the losses were to unidentified polar products not eluted from HPLC. Authentic hydroxyethyl was synthesized from doxorubicin by reductive alkylation with glycolaldehyde. Antitumor potency was comparable to that of doxorubicin rather than of cyanomorpholine.

Animals↗
PubMed1986

Renal cystic disease in childhood.

The authors present a comprehensive review of the diagnostic features of eight forms of renal cystic disease that occur in childhood. Sonographic findings are emphasized.

Child↗