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Biomedical subjects

R Smith

Publications and source records attributed to R Smith.

At least 1,747 records · Page 97Linked to original sources
PubMedDate not supplied

Progressive osseous heteroplasia: a case report.

We report the case of a young female who, from infancy, suffered extensive, progressive, heterotopic ossification of her left lower limb. Heterotopic ossification, which was largely but not exclusively intramembranous in type, was most marked in subcutaneous fat but was also noted in muscle and deep connective tissue. The spectrum of changes noted suggests that this congenital disorder of soft tissues is similar to that recently described as progressive osseous heteroplasia.

Abdomen↗
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The relationship between changing values of pregnancy-associated plasma protein-A in late pregnancy and the onset of labour.

The pattern of change of PAPP-A was established in three separate groups of patients. Day-to-day change from the 38th week was measured in six healthy patients whose pregnancies ended in spontaneous labour. The slow fluctuations of PAPP-A suggest that values found in labour are a consequence of events prior to the onset of labour. Increases of PAPP-A during the last few days of pregnancy and into labour were compared in patients going into labour spontaneously and patients who were induced. The induced patients showed a sharper increase in PAPP-A during this interval than the spontaneous onset group. A comparison at an earlier stage of pregnancy of PAPP-A increase was made between normal pregnancies going into labour on or before 280 days and those who went into labour later. Between 31 +/- 1 and 35 +/- 1 weeks, those who delivered in the earlier group showed a sharper rise in PAPP-A. It seems likely that the behaviour of PAPP-A in late pregnancy is the consequence of uterine activity and it seems unlikely that an increasing level of PAPP-A in itself has anything to do with the initiation of spontaneous labour.

Female↗
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Carcinoma of the uterine cervix metastatic to behind the zygomatic arch: a case report.

PURPOSE: We propose to present a novel case of a genital malignancy metastatic to the head and neck. Carcinoma of the uterine cervix is the third most frequent malignancy of the female genital tract. Early detection and improved radiation and surgical techniques have resulted in better control of the pelvic tumor and a greater incidence of distant metastasis. Metastases to the soft tissue of the head and neck region have not been reported. METHODS: We present the first known case of a 35-year-old woman with cancer of the uterine cervix who presented with metastasis to the soft tissue behind the zygomatic arch. RESULTS: The patient received radiation therapy to the zygomatic region and cisplatin therapy with a near-complete remission. CONCLUSION: This case shows that not all squamous cell cancers detected above the clavicles are from a thoracic or a head and neck primary tumor. The atypical location should alert the physician to suspect distant metastasis, rather than locoregional disease.

Adult↗
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The validity of cognitive distance in oral and written discourse.

Oral and written discourse samples of adolescents with closed head injury (CHI) and controls were analyzed to determine if efficiency and coherence measures changed as the length of their picture descriptions increased. The hypothesis was that as ideas were elaborated, the number of words used to express an idea would increase and the conceptual connectedness of ideas would decrease. This research study supported this expectation for efficiency in normal oral and written discourse but not for the discourse of participants with CHI. Further, the efficiency measure significantly differentiated the writing and speaking of the two groups as the picture descriptions were elaborated. Coherence ratings did not distinguish the development of discourse within or between groups

Adolescent↗
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Expression of the 11beta-hydroxysteroid dehydrogenase type II enzyme in breast tumors and modulation of activity and cell growth in PMC42 cells.

Manipulating the metabolism of glucocorticoids may serve as a useful adjunct in the treatment of breast cancer. The 11beta-hydroxysteroid dehydrogenase type 2 enzyme (11betaHSD2) potently inactivates glucocorticoids thereby protecting the non-selective mineralocorticoid receptor (MR) in fluid transporting tissues. In the present study, Western blot analysis showed the presence of 11betaHSD2 in 66% of the breast tumor samples. The 11betaHSD2 and MR are also present in the breast tumor cell line PMC42. Glycyrrhetinic acid abolished glucocorticoid metabolism and inhibited cell growth by 40%, the latter at concentrations consistent with glucocorticoid receptor (GR) and MR binding studies. Metabolism was increased by glucocorticoids, the anti-glucocorticoid RU 38486 and anti-mineralocorticoid spironolactone, while aldosterone had no effect. Neither cortisol nor aldosterone affected cell proliferation, but both RU 38486 and spironolactone caused a significant decrease in cell number. The effects of RU 38486 were only observed at micromolar concentrations and are inconsistent with an action via GR or progesterone receptor (PR). This study shows that 11betaHSD2 activity and cell proliferation of PMC42 cells can be modulated via steroid receptors.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
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Environmental Exposure↗
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Light-chain phosphorylation controls the conformation of vertebrate non-muscle and smooth muscle myosin molecules.

Phosphorylation of the 20,000-molecular weight (Mr) light chains of vertebrate non-muscle (thymus) and smooth muscle (gizzard) myosins regulates the assembly of these myosins into filaments in vitro. At physiological ionic strength and pH, nonphosphorylated smooth muscle and non-muscle myosin filaments are disassembled by stoichiometric levels of MgATP, forming species having sedimentation coefficients of approximately 11S (range 10-12S; myosin monomers in high salt sediment at 6S). When the 20,000 (20K)-Mr light chains on these 11S myosin species are phosphorylated by the light-chain kinase/calmodulin-Ca2+ complex, the inhibitory effect of the light chains on filament formation is removed and the myosins reassemble into filaments which are stable in MgATP. It was originally suggested that the 11S myosin species was a dimer, previously suggested as a building block for smooth muscle and non-muscle myosin filaments. It has since been shown, however, that 11S smooth muscle myosin is monomeric and has a folded conformation rather than the extended shape characteristic of monomeric myosin in high salt. Here we show that 11S non-muscle myosin is also folded and that phosphorylation of the 20K-Mr light chains of both vertebrate non-muscle (thymus) and vertebrate smooth muscle (gizzard) myosins causes these folded 11S molecules to unfold into the conventional extended monomeric form, which is able to assemble into filaments.

Animals↗
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Direct enzyme transfer from lymphocytes is specific.

Lymphocytes are known to interact directly with other cells in vivo and in vitro, and have recently been shown to transfer the lysosomal enzyme, beta-glucuronidase, to fibroblasts from patients with an inherited deficiency of the enzyme. This process requires cell-cell contact, is unaffected by inhibitors of 'classical' receptor-mediated endocytosis and is abolished by inhibitors of protein synthesis. Although it is not yet known to what extent the transfer of enzymes by direct cellular interaction is a general phenomenon, a similar mechanism could possibly be involved in the transfer of other lysosomal enzymes in vivo and in the exchange of protein in vitro. We show here that the direct transfer of enzymes from lymphocytes to fibroblasts is restricted to only certain lysosomal enzymes.

Animals↗
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Mitochondria control expression of a murine cell surface antigen.

Maternally transmitted antigen (Mta) is a murine cell-surface molecule defined by the reactivity of specific H-2 nonrestricted cytotoxic T lymphocytes (CTL-s). Maternal transmission appears to be under control of a stable genetic factor in the cytoplasm of the ovum. In view of the known maternal inheritance of mitochondria we have assessed their involvement in Mta expression using the mitochondria specific poison Rhodamine 6G (R6G). We report here that Mta expression in somatic cell hybrids requires functional mitochondria from the Mta+ parent cell line. Mta expression was dominant in hybrids from the fusion of Mta+ and Mta- cells. However, pretreatment of the Mta+ parent with R6G resulted in hybrids which were Mta-, or diminished in Mta expression. These data strongly implicate mitochondrial DNA (mtDNA) in the expression of a cell-surface molecule, and define a system for studying a previously unrecognized mitochondrial function. To our knowledge, this is the first evidence for mitochondrial control of the expression of a cell membrane molecule in eukaryotes.

Animals↗
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Racism and health care access: a dialogue with childbearing women.

The rates of low birth weight and preterm delivery are twice as high for African Americans as they are for Whites in the United States. Racism and health care access may be factors in this twofold disparity. To investigate this possibility, we conducted a qualitative study with African American prenatal and postpartum women (N = 14). In 1- to 2-hr interviews, we asked the participants to describe their ability to access health care and their experiences of racism. We then independently and collectively coded the data until consensus (95%) was obtained. Data categories included access to care, treatment, differences in care, stereotypes, and racism. Three themes emerged from the interviews: (a) the pervasiveness of the stereotype of pregnant African American women; (b) a care that is indifferent, inaccessible, and undignified; and (c) the totality of racism. These themes encompass social, political, and economic factors affecting the experiences of childbearing African American families and mandate the need for further investigation and intervention.

Adolescent↗
PubMedDate not supplied

The impact of work environment, utility, and sampling design on occupational magnetic field exposure summaries.

Most recent epidemiologic studies investigating the potential health effects of occupational magnetic field (MF) exposure have relied on MF measurement data linked to job titles. These measurements are summarized by occupational categories, which represent similar groups of job titles. However, job titles alone explain only a small proportion of exposure variability. A comprehensive MF occupational exposure database was used to (1) develop summary job-specific estimates of magnetic field exposure, (2) evaluate the impact of incorporating work environment data to improve electric and magnetic field exposure assessment, and (3) evaluate the use of random versus nonrandom sampling when estimating mean MF exposure levels by occupational categories. Uniform classification systems were developed for occupational and work environment data. A factorial design was used to summarize and calculate arithmetic means and 95% confidence intervals for occupational MF data, assuming that the total variation in MF exposure resulted from variation in occupation, work environment, utility, worker, and day. Occupation-specific means varied across different work environments, particularly for craft workers. Although within-worker and between-worker variability account for a large proportion (over 50%) of exposure variation, work environment (24%) accounted for more exposure variability than occupation (4.9%) or utility (15%). Some differences were observed when results were compared from surveys that used random and nonrandom sampling; however, these differences were not consistent or systematic. It was concluded that MF exposure assessment should consider work environment in addition to job title to reduce exposure misclassification.

Data Collection↗
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Spontaneous dissection of the vertebral artery: MR findings.

Spontaneous (nontraumatic) dissection of the carotid and vertebral arteries, once thought to be rare, is being recognized and reported more frequently. We report one case of spontaneous dissection of the vertebral artery initially diagnosed by magnetic resonance imaging and subsequently confirmed by angiography.

Aortic Dissection↗
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MR appearance of uterine dehiscence in the post-cesarean section patient.

PURPOSE: CT has been shown to be unreliable for detecting uterine dehiscence in the postoperative period after cesarean section (c-section). The purpose of this investigation is to describe the MR appearance of uterine dehiscence in this setting and identify features that distinguish complete from partial dehiscence. METHOD: Over an 82 month period, all charts and MR reports of patients that underwent MRI of the pelvis after c-section were reviewed for uterine dehiscence. Altogether, 55 patients were imaged. Positive cases for dehiscence were retrospectively reviewed by two radiologists. Imaging criteria for complete dehiscence consisted of transmural disruption. Criteria for partial dehiscence consisted of disruption of the endometrial and/or serosal layer, without transmural extension. RESULTS: On MRI, five patients demonstrated abnormalities suggestive of incisional dehiscence. Based on these imaging criteria, two of these showed complete dehiscence that was proven at surgery and three showed findings of partial dehiscence. The optimal imaging plane was perpendicular to the incision. CONCLUSION: MR features may be utilized to identify total uterine dehiscence and may be more effective than CT.

Adolescent↗
PubMedDate not supplied

Effects of concentration and steric configuration of propranolol on AV conduction and ventricular repolarization in the dog.

To investigate the electrophysiological effects of propranolol in vivo over a wide range of plasma concentrations and to distinguish effects due to beta-blockade from those due to a direct membrane action, His bundle electrograms were recorded, and ventricular effective refractory periods (VERP) and monophasic action potential duration (MAP) were measured in anesthetized control dogs and in dogs given three graded infusions of d- or dl-propranolol. Dogs were excluded if the plasma concentrations attained did not fall in predefined ranges of 25--125, 125--700, and 700--3,000 ng/ml. Isoproterenol sensitivity tests were performed to determine the relative beta-blocking potency of the isomers at the three concentration ranges. The highest concentration of d-propranolol had approximately the same beta-blocking potency as the lowest concentration of dl-propranolol. Mean AH and HV intervals in the His bundle electrogram increased with the concentration of dl-propranolol, and the increase was greater than with d-propranolol (p less than 0.03) at the first and second concentration steps but not significantly different at the highest concentrations of d- and dl-propranolol. VERP and MAP increased directly with concentration of d- and dl-propranolol. Although the mean increases of VERP and MAP tended to be greater in the dl-propranolol group, the differences between d- and dl-propranolol were not statistically significant at any concentration. We conclude that prolongations of atrioventricular and His-Purkinje conduction are stereospecific responses and are due to beta-blockade. The specific mechanism for the prolongation of ventricular repolarization and refractoriness are effects of propranolol that could not be definitively classified in this study.

Action Potentials↗
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Genetic counseling after implementation of statewide cystic fibrosis newborn screening: Two years' experience in one medical center.

PURPOSE: To study the follow-up of genetic counseling performed in families with a newborn detected with one cystic fibrosis (CF) mutation in a statewide newborn screening pilot program. METHODS: Newborns in Massachusetts with an elevated trypsinogen level on newborn screen who are found to have one mutation for CF on a selected mutation assay undergo sweat testing for CF, and their families receive genetic counseling. The genetic counseling focuses on carrier risk for the parents of the newborn and offers carrier testing. We studied the yield of genetic counseling and the resulting genetic testing performed on the families of infants found to be CF carriers who underwent sweat testing in a single institution. RESULTS: Of 102 newborns evaluated with a single CF mutation, 2 (twins) had sweat test results consistent with CF. A total of 101 families were counseled, and 95 were offered DNA-based CF carrier testing. Eighty-two percent of all parents chose to have CF carrier testing, and in five couples, both members were carriers. One of these couples (whose newborn was only a carrier) had an older child who was unexpectedly found to have CF. CONCLUSIONS: Sweat testing of newborns at increased risk for CF in conjunction with genetic counseling for their parents allows identification of infants with CF, finds couples at high risk for having a child with CF, identifies previously undiagnosed siblings with CF, and allows for potential identification of CF carriers in the extended family.

Chlorides↗