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Biomedical subjects

R Smith

Publications and source records attributed to R Smith.

At least 901 records · Page 50Linked to original sources
PubMed1991

A male with type I orofaciodigital syndrome.

We describe a three generation family with three females showing minor features of orofaciodigital syndrome type I and a severely affected male in the third generation. In addition to the classical features of OFD I, the male had bilateral duplication of the halluces, a feature diagnostic of OFD II, and an atrioventricular septal defect. Heart defects have not previously been reported in OFD I but have been reported in OFD II. It is important to examine the mothers of all male neonates with orofaciodigital syndrome with care before making a diagnosis of OFD II.

Adult↗
PubMed1991

Prenatal diagnosis of osteogenesis imperfecta by identification of the concordant collagen 1 allele.

Dominantly inherited osteogenesis imperfecta is consistently linked to the two loci encoding the alpha 1 and alpha 2 subunits of collagen 1, the predominant bone collagen. We have performed several prenatal diagnoses based on identification of the segregating allele at the concordant locus in chorionic villus samples both in families where the linkage can be independently shown and in those where it cannot. Especially in the latter category, calculation of the final risk must incorporate an estimate of genetic heterogeneity within the OI population to give a prior probability of linkage. This figure can then be modified for each family by additional information from concordant meioses.

Alleles↗
PubMed1991

Measuring body fat: calibrating the rulers. Intermethod comparisons in 389 normal Caucasian subjects.

A systematic study of 389 normal Caucasians stratified for sex and age compared all of the traditional methods for measuring fat: body water, underwater weighing, body potassium, and anthropometrics and the newer methods of dual-photon absorptiometry, bioimpedance analysis, and total body electrical conductivity. Measurements by all methods are highly intercorrelated, but methods differences show the population means for fat percent to range from 26 to 35% of body weight across eight methods. All methods show increasing fat (as % body weight) with age in both sexes but vary in secular slope. The goal of this report is to provide direct translations between each of the eight methods. Intermethod comparison equations are given as simple linear regressions by using each method both as dependent and independent variable for each sex, permitting translation for results by any method to any other.

Adipose Tissue↗
PubMed1991

Abnormal epithelial transport in cystic fibrosis jejunum.

Abnormal epithelial electrolyte transport has been identified in a range of cystic fibrosis (CF) organs and appears to account for the various clinical manifestations of the disease. The aim of this study was to further define the Cl- secretion defect in CF jejunum. Excised jejunum was obtained from 11 CF patients and 12 controls. Transport studies were performed on stripped epithelium in vitro under short-circuited conditions in Ussing Chambers. 3-Isobutyl-1-methylxanthine (IBMX) (300 microM) significantly increased Cl- secretion in control (-2.3 +/- 0.6 to -3.3 +/- 0.7 mueq.cm-2.h-1; P less than 0.01, paired t test; n = 5 subjects) but not in CF jejunum (-0.5 +/- 0.3 to -0.1 +/- 0.4; n = 4). However in contrast to control jejunum, net Na+ absorption in CF jejunum was higher in the IBMX (1.3 +/- 0.5 mueq.cm-2.h-1) compared with basal periods (0.6 +/- 0.3; P less than 0.05, paired t test). IBMX stimulation of tissue adenosine 3',5'-cyclic monophosphate (cAMP) was similar in both control and CF jejunum. A range of secretagogues known to induce secretion in mammalian intestine, including dibutyryl cAMP (DBcAMP), DBcGMP, Ca2+ ionophore A23187, and the protein kinase C activator 4 beta-phorbol 12,13-dibutyrate, failed to induce secretion in CF jejunum. In conclusion, CF jejunum failed to exhibit Cl- secretion and also demonstrated abnormalities of Na+ absorption. These results support the view that the defect lies at a site distal to the intracellular messengers. Moreover, these abnormalities of intestinal electrolyte transport may account for some of the gastrointestinal manifestations of the disease such as meconium ileus and distal intestinal obstruction syndrome.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Transcriptional regulation of the int-2 gene in embryonal carcinoma cells.

The int-2 gene, which encodes a member of the fibroblast growth factor family, is expressed at specific sites and times during mouse development. In certain embryonal carcinoma cell lines, multiple int-2 transcripts accumulate when the cells are induced to differentiate with retinoic acid and dibutyryl cyclic AMP. Nuclear run-on analyses indicate that the apparent induction of int-2 expression results from an increase in the rate of transcription initiation. Six distinct types of RNA have been delineated, originating from three promoters and terminating at either of two polyadenylation sites. Since each transcript appears to encode the same protein, this complexity may reflect the need for lineage-specific or differentiation-dependent control of expression. By comparing the kinetics of induction and turnover of the different RNA species, we show that the choice of promoter or length of the 3'-untranslated region has no significant effect on the half-lives of the various mRNAs. To further evaluate control at the transcriptional level, we have shown that a 1.7-kilobase fragment of int-2 genomic DNA, when fused to the chloramphenicol acetyltransferase gene, can act as a regulated promoter(s) in differentiated versus undifferentiated embryonal carcinoma cells. This segment of DNA encompasses the three promoter regions previously delineated by RNase mapping plus about 900 base pairs of additional upstream sequences.

Animals↗
PubMed1991

Renal failure in adult onset hypophosphatemic osteomalacia with Fanconi syndrome: a family study and review of the literature.

Follow-up of a previously reported family with dominantly inherited adult onset hypophosphatemic osteomalacia with Fanconi syndrome and diabetes mellitus has shown that both the proposita and her affected sister have developed renal glomerular failure. We describe the evolution of renal failure in this family and discuss the possible mechanisms involved. The development of renal tubular acidosis in this condition further impairs renal function and we suggest that correction of systemic acidosis might improve renal function and prevent further decline in these patients.

Acidosis, Renal Tubular↗
PubMed1991

A preliminary study of the effects of cardiac procedures on cognitive performance.

The effects of three commonly performed cardiac procedures on cognitive performance were evaluated in patients undergoing coronary artery bypass graft (CABG) surgery (N = 20), percutaneous transluminal coronary angioplasty (PTCA) procedure (N = 8), or cardiac valve repair (N = 11). Patients completed a neuropsychological test battery on the day prior to their surgery and at discharge. Results showed that valve and CABG patients exhibited declines in performance on the Digit Symbol subtest, while PTCA patients did not change. Reaction time performance improved for the PTCA patients but declined significantly for valve patients. These results suggest that common cardiac procedures may have measurable effects on cognitive performance, as assessed by a relatively brief test battery.

Angioplasty, Balloon, Coronary↗
PubMed1991

The interaction of pseudohalides with the phospholipid head-group: a nuclear magnetic resonance study.

Liposomes have been studied by means of high-field magnetic resonance techniques. The choline N+(CH3)3 group showed two proton resonances for phosphatidylcholine whereas the addition of a charged species to the phospholipid resulted in a single N+(CH3)3 resonance. Upon the addition of either of two linear pseudohalide anions, the two resonances for phosphatidylcholine were further split whereas for the mixture of lipids containing a charged species, the single head-group resonance was now split. The presence of a negative charge on the liposome does not prevent the anion-liposome interaction observed for neutral liposomes. Incorporation of cholesterol into the negatively charged liposomes results in a clear initial splitting of the head-group proton signal in a manner very similar to that for neutral liposomes; this head-group signal is then further split upon anion addition. The small splitting involved suggests a weak pseudohalide-liposome interaction whose magnitude depends on the position of the anion in the lyotropic series. The phosphorous NMR signal from the head-group is unaffected by the pseudohalide interaction whereas the carbon signals from the N+(CH3)3 groups are affected, indicating that the initial anion interaction is localized to the region of the choline groups of the liposome. After the initial exposure of the liposome to the anion, however, the splitting decreases with time, indicating that the anions have entered the liposome and interact with both inside and outside head-groups.

Carbon Isotopes↗
PubMed1991

Corneal topography as a predictor of refractive change in the prospective evaluation of radial keratotomy (PERK) study.

The first operated eyes of 435 patients undergoing radial keratotomy in the Prospective Evaluation of Radial Keratotomy (PERK) study were evaluated by photokeratography to document the preoperative and postoperative corneal shape. We determined by regression analysis and analysis of variance that the corneal shape preoperatively improved the prediction of the corneal shape 6 months postoperatively in the 3-mm-clear-zone population. The reduction of myopia in all 435 eyes ranged from 1.25 to 9.75 diopters. We studied the effect of the preoperative corneal shape on this variability in the outcome of the surgery using rings 2 and 7 on photokeratography and corneal diameter. In the 3-mm-clear-zone group, eyes with flat prolate corneas had a greater reduction in myopia (4.65 D); those with steeper, more spherical corneas had less reduction in myopia (3.48 D). In addition, eyes with a 3-mm clear zone and flat central corneas alone (8.0 mm = 42.19 D) flattened approximately 0.75 D more than those with steep central corneas (7.0 mm = 48.21 D). In the 3.5-mm and 4.0-mm clear zone groups, the change in corneal curvature was not related to the preoperative curvature. A stepwise regression analysis of the 151 eyes in the 3.0-mm-clear-zone population demonstrated the following predictive equation for radial keratotomy; change in cycloplegic refraction = -14.55 + [-2.097 x average ring-2 radius] + [3.605 x average ring-7 radius] + [0.69 x horizontal corneal diameter] + [0.079 x age] + [-0.379 x spherical equivalent cycloplegic refraction]. There was a 1.17-D observed difference in the effect of radial keratotomy between those eyes with a steep/steep corneal topography (7.2% of the 3.0-mm-clear-zone population) and the flat/flat topography (29% of the 3.0-mm-clear-zone PERK population). A knowledge of corneal topography provides an additional tool for understanding the operative variability of radial keratotomy.

Cornea↗
PubMed1991

Neuroimaging of AIDS.

A retrospective review of the neuroimaging procedures of 84 patients with the diagnosis of AIDS was performed. Both computed tomography (CT) and magnetic resonance imaging (MRI) procedures were evaluated for the presence of atrophy, enhancing lesions and focal non-enhancing lesions. The imaging findings in several infectious conditions (toxoplasmosis, cytomegalovirus, papovavirus, HIV virus, tuberculosis and histoplasmosis) are described. Intracranial lymphoma, another complication of AIDS, also is discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1991

D11S287, a putative oncogene on chromosome 11q13, is amplified and expressed in squamous cell and mammary carcinomas and linked to BCL-1.

Approximately 15 to 20% of primary breast cancers and an even higher proportion of squamous cell carcinomas of the head and neck show amplification of DNA markers on band q13 of human chromosome 11. However, known genes within the amplified region, such as the FGF-related oncogenes INT-2 and HST-1, are very rarely expressed in these tumors. Here we show that another candidate oncogene, designated D11S287, implicated in the pathogenesis of parathyroid adenomas, is also amplified in breast cancers. Significantly, it is consistently coamplified with INT-2 and HST-1 in 36 out of 202 primary tumors, including one case in which the amplified unit did not encompass the translocation breakpoint marker BCL-1. This implies that D11S287 is on the same side of the breakpoint as INT-2, and pulsed-field gel electrophoresis indicates that D11S287 is less than 250 kb from the BCL-1 marker. Since D11S287 RNA was present at elevated levels in a group of tumors and cell lines in which the 11q13 region is amplified, it may be the key oncogene on this amplified unit, and could also be activated by BCL-1 translocations.

Blotting, Southern↗
PubMed1991

The value of a new family practice center patient to the academic medical center.

BACKGROUND: Family practice centers are important contributors to the financial viability of academic health centers, although they often are not the direct beneficiaries of their own labor. The greater time commitment and lower costs of most primary care creates significant financial hardships for departments of family medicine in university centers. This study describes the use of inpatient and outpatient health care services by new patients at a university family practice center. METHODS: A sample of 215 new adult enrollees at a university family practice center were examined for a 1-year period after their initial visit to the center. Total billings by the university hospital, specialty services, and the family practice center were tabulated by insurance type. RESULTS: Medicare patients generated the highest average charges (+2501 per patient per year); self-indemnity patients generated the lowest average charges (+301 per patient per year). The largest portion of health services charges was generated by the university hospital inpatient service, which was responsible for approximately 60 cents of every dollar billed to patients in this study. Conversely, the Family Medicine Department billings generated only 17% of the total charges. CONCLUSIONS: The findings of this study indicate that university-based family practice centers are significant contributors to the financial and educational base of the academic health center. If family medicine and associated primary care centers are forced to reduce their size or services because of financial difficulties, the impact will be felt by the university hospitals and by other specialty departments.

Academic Medical Centers↗