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Biomedical subjects

J T Davis

Publications and source records attributed to J T Davis.

At least 19 recordsLinked to original sources
PubMed1995

Hypoplasia of the eustachian valve and abnormal orientation of the limbus of the foramen ovale in hypoplastic left heart syndrome.

We examined the eustachian valve and the limbus of the foramen ovale in 42 hearts with hypoplastic left heart syndrome (HLHS) and in 16 normal hearts. In HLHS, only 4.8% of the eustachian valves were moderately to well developed, whereas the remaining 95.2% were abnormal (p < 0.001): 92.9% of the eustachian valves were absent or markedly hypoplastic, and 2.4% had an abnormally redundant and enlarged eustachian valve. The eustachian valve was well developed in 87.5% of normal hearts. In addition, the lesser development of the eustachian valve seemed to correlate with lesser development of the left side of the heart. The limbus was well developed in 100% of the normal hearts and moderately to well developed in only 33.3% of the HLHS group (p < 0.001). Most hearts in the HLHS group had marked hypoplasia of the limbus, which was rotated and deviated so as to be close to the superior vena caval entrance.

Aortic Valve↗
PubMed1995

Clinical pathways can be based on acuity, not diagnosis.

The standardization of medical practice is gaining acceptance as a technique for controlling length of stay and hospital charges, while maintaining quality. Most clinical pathways address specific diagnoses or procedures, but we have developed a new approach in which pathways for cardiac care are based on acuity. All congenital cardiac surgical care rendered at Columbus Children's Hospital now falls within one of four such clinical pathways. This simplified approach is easy to use and has been well accepted. Our experience in a group of 107 consecutive patients treated in this fashion is described. The results of variance analyses, along with length of stay and charge data, are presented to demonstrate the degree to which resource utilization can be standardized in this widely variable group of patients whose problems were made cohesive by classification according to acuity level. We conclude that the resultant standardization offers considerable advantages for the managed care environment.

Cardiac Surgical Procedures↗
PubMed1995

Lateral thoracic expansion for Jeune's asphyxiating dystrophy: a new approach.

A new procedure is described for thoracic expansion in Jeune's asphyxiating dystrophy. The chest wall is enlarged by division of ribs and underlying tissue in a staggered fashion so that either rib or periosteum covers the lung. New bone formation has been demonstrated so that a viable enlargement has been obtained. The clinical result is excellent to date.

Asphyxia Neonatorum↗
PubMed1995

Retinol processing by the peritubular cell from rat testis.

The cells that surround and support the seminiferous epithelium of the tubules in the testis, i.e., the peritubular or myoid cells, are known to contain relatively high amounts of cellular retinol-binding protein (CRBP). This suggests that they may play an important role in the movement or metabolism of retinol (vitamin A alcohol), which is required for the maintenance of spermatogenesis. Peritubular cells in culture, isolated from the testes of the 20-day-old rat, maintained high levels of CRBP and had the ability to internalize retinol from retinol-binding protein (RBP), the blood transport protein for retinol, in a manner suggesting a receptor-mediated process. Little of the internalized retinol was esterified, in contrast to what occurs in other cell types that contain high amounts of CRBPs, and very little, if any, lecithin-retinol acyltransferase activity was present in microsomes obtained from the cultured cells. The cells did, however, have the ability to synthesize and release their own RBP to the medium. This suggests that retinol from the blood may actually reach the seminiferous epithelium by passing across the peritubular cell, released on a new molecule of RBP, rather than by entering into the tubule bound to the preexisting RBP present in the interstitial fluid.

Acyltransferases↗
PubMed1994

Synthesis and secretion of retinol-binding protein and transthyretin by cultured retinal pigment epithelium.

Recent studies indicate that the retinal pigment epithelium (RPE) may serve as an extrahepatic source of retinol-binding protein (RBP) and transthyretin (TTR) for the retina by virtue of the fact that this cell layer is the exclusive retinal location for mRNA coding for these proteins [Herbert, J., et al. (1991) Invest. Ophthalmol. Vis. Sci. 32, 302-309; Cavallaro, T., et al. (1990) Invest. Ophthalmol. Vis. Sci. 31, 497-501], although the proteins themselves are present in a variety of retinal neurons. It is therefore necessary to determine whether these mRNAs are translated and whether their translated products are secreted like hepatic RBP and TTR. Metabolic labeling of cultured bovine RPE with [35S]cysteine and [35S]methionine and subsequent analysis of newly synthesized proteins in the conditioned medium by affinity chromatography, gel filtration, partial amino acid sequence analysis, and autoradiography of electrophoretograms indicate that both RBP and TTR are synthesized and secreted by the RPE. Moreover, for cells grown in chambers with permeable supports, the predominant direction for secretion was into the apical medium. The mean apical:basal ratio after 72 h of incubation was 9.2 for TTR and 4.5 for RBP. A function for these proteins in the neurosensory retina remains speculative. They could be involved in the delivery of all-trans-retinol to amacrine and Müller cells as a precursor for retinoic acid, since these cells are known to contain cellular retinoic acid binding protein [Gaur, V.P., et al. (1990) Exp. Eye Res. 50, 505-511; Milam et al. (1990) J. Comp. Neurol. 296, 123-129].(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

1H NMR studies on an Asn-linked glycopeptide. GlcNAc-1 C2-N2 bond is rigid in H2O.

The conformation of an Asn-linked glycopeptide in H2O was studied by two-dimensional 1H NMR. Nonexchangeable proton and exchangeable amide (NH) proton resonances were assigned for the hen ovomucoid glycopeptide 1, Ser-Ile-Glu-Phe-Gly-Thr-Asn Ile-Ser-Lys, with pentasaccharide Man alpha 1-3 (Man alpha 1-6)Man beta 1-4GlcNAc beta 1-4GlcNAc beta 1-NH attached to the Asn7 gamma-carboxamide. The pentasaccharide increases the local correlation times of amino acid residues near the N-glycosylation site. Nuclear Overhauser effect (NOE) measurements on 1 and the corresponding Man3-GlcNAc2 pentasaccharide 3 show that the attached peptide does not perturb O-glycoside conformation. Sequential dNN (i, i + 1) NOEs in the Thr6-Ser9 region indicate populations of folded structure near the N-glycosylation site of both glycopeptide 1 and aglycosyl peptide 2. However, the Man3GlcNAc2 pentasaccharide does not dramatically affect the average conformation of either the peptide backbone or the Asn7 side chain. GlcNAc NH protons were studied at pH 3.0; and NOE and 3JNH data were used to constrain the glycopeptide's GlcNAc-1 side chain dihedral angle (tau) (C1-C2-N2-C7(Ac)). The glycopeptide's core GlcNAc-1 C2-N2 side chain bond is not flexible in H2O. A strong GlcNAc-1 NH2-H3 NOE, a medium strength NH2-H1 NOE, and a weak NH2-H2 interaction suggest that GlcNAc-1 has a rigid C2-N2 bond, with tau between 95 and 115 degrees. No evidence was found for intramolecular hydrogen bonds restricting this C2 side chain torsion. It may be that GlcNAc-1's rigid planar N-glycosidic linkage limits the conformational space available to the adjacent C2 acetamido side chain.

Acetylglucosamine↗
PubMed1994

Cavopulmonary anastomotic aneurysm: a complication in pulsatile pulmonary arteries.

An aneurysm of a left superior vena cava developed after anastomosis to the left pulmonary artery during repair of an atrioventricular septal defect with a persistent left superior vena cava entering directly into the left atrium. We believe this implies caution should be used in accepting the recent suggestion of using a bidirectional cavopulmonary connection to a pulsatile pulmonary arterial circuit as a way of allowing anatomic correction of atrioventricular septal defect with a small right ventricle.

Aneurysm↗
PubMed1994

Coronary artery fistula in the pediatric age group: a 19-year institutional experience.

Ten patients with coronary artery fistulae were identified from records at Columbus Children's Hospital between 1974 and 1993. Clinical presentations of patients were quite variable, from 1 day to 20 years of age. Symptoms ranged from none to severe cardiorespiratory failure requiring extracorporeal membrane oxygenation. Long term follow-up revealed one sudden death and one spontaneous closure of the fistula. This lesion should be ruled out in patients who present as extracorporeal membrane oxygenation candidates. Patients with mild forms of this lesion may be followed up medically if the left to right shunt is inconsequential, because spontaneous closure is a possibility. Because of the risk of sudden death, close long-term follow-up is mandatory even for operated patients, and antiplatelet therapy should be considered for these patients.

Adult↗
PubMed1994

Use of cardiac catheterization in pediatric cardiac surgical decisions.

Current practice patterns relating to pediatric cardiac catheterization (Cath) have considerable economic implications. The decreased cost and risk of noninvasive methods such as echocardiography (ECHO) and magnetic resonance imaging (MRI) make them attractive alternative diagnostic methods if they can sufficiently define cardiac anatomy and the need for surgical intervention. We reviewed a recent cardiac surgical series of 465 cases in 1.5 years to determine how often a Cath was performed prior to surgery. Overall, 59.4% of the procedures were preceded by a Cath (76% of open heart operations, and 26.7% of closed heart operations). We specify the situations where we feel enough information is available for preoperative decision making from non-invasive testing, and we present some diagnostic pitfalls that have been encountered.

Cardiac Catheterization↗
PubMed1993

Mobility at the TpA cleavage site in the T3A3-containing AhaIII and PmeI restriction sequences.

Lefevre et al. originally observed conformational transitions at the TpA step in the TTAA Pribnow box sequence of the trp promoter [Lefevre, J.-F., Lane, A. N., & Jardetzky, O. (1985) FEBS Lett. 190, 37-40]. In 500-MHz 1H NMR studies on the TnA(n)-containing DNA oligonucleotides [d(CGAGGTTTAAACCTCG)]2, [d(GCTCCTTTAAAGGAGC)]2, and [d(GCCGTTAACGGC)]2, we observe that, in addition to the H2 proton (which resides in the minor groove of DNA), the H8 proton of the first adenine (which resides in the major groove) is also broadened due to motion at the TpA junction. In analogous 16-mers where the T3A3 segment has been replaced by an A3T3 sequence, and therefore contains CA, GA, and AT steps (but no TA steps), all adenine proton resonances are narrow, indicating that the broadening occurs only at TpA steps. Assuming chemical exchange in the form of conformational dynamics, e.g., oscillation of the purine base about the glycosidic torsion angle, the experimental 500-MHz 1H T1 rho and 2D-NOESY data were used to constrain the correlation time of the internal motion to a range between the T1 and T1 rho minima. Calculated line shapes using a two-site exchange model indicate that the motion has an amplitude of 20-50 degrees with an associated tau c of ca. 1.6 x 10(-4) to 1.0 x 10(-5) s rad-1, respectively. The mobility appears to be a consequence of the structure at the TpA junction which is characterized by (1) a wide minor groove between two regions of narrow minor groove, (2) an unusual average orientation of the adenine heterocycle probably resulting from a poor base-stacking interaction of the adenine with the preceding thymine, and (3) a sharp discontinuity in the sugar conformation at the TpA step.

Base Sequence↗
PubMed1993

Sequence-selective metal ion binding to DNA oligonucleotides.

Metal ion titrations of several DNA oligonucleotides, 10 dodecamers and one decamer have been monitored by 1H NMR spectroscopy in order to elucidate metal ion binding patterns. Also, the effects of paramagnetic impurities on resonance linewidths and NOESY cross-peak intensities have been reversed by EDTA back-titration experiments. 1H 1D NMR spectra were recorded after successive additions of aliquots of different metal salts to oligonucleotide samples. Paramagnetic manganese(II) salts were used in most cases, but a few samples were also titrated with diamagnetic zinc(II). From this study, we conclude that there exists a sequence-selective metal ion binding pattern. The metal ions bind predominantly to 5'-G in the contexts 5'-GC and 5'-GA. The order of preference seems to be GG > or = GA > GT > > GC. No evidence of metal ion binding to 5'-G in 5'-GC steps or to non-G residues was found. The H6 or H8 resonances on preceding (5'-) bases were affected by the adjacent bound paramagnetic metal ion, but no effect was observed on the protons of the succeeding (3'-) base. The metal binding site in the duplexes is most likely at G-N7, as manifested by the pronounced paramagnetic line broadening or diamagnetic shift of the G-H8 signal. This sequence selectivity may be qualitatively explained by a sequence-dependent variation in the molecular electrostatic potentials of guanine residues (MEPs) along the oligonucleotide chain.

Base Sequence↗
PubMed1992

Myxoid heart disease: an assessment of extravalvular cardiac pathology in severe mitral valve prolapse.

Because of the microscopic features of the affected leaflets in mitral valve prolapse (MVP), myxoid degeneration of the valve is a common pathologic designation applied to this condition. We undertook this study as a means of gaining an insight into the occurrence and prevalence of extravalvular cardiac alterations in hearts with severe MVP. Tissues of 24 hearts with severe myxomatous transformation of the mitral valve as the sole cardiac abnormality were examined. Eighteen of the 24 subjects with severe MVP died suddenly. Only two of these had pathologic evidence of severe mitral insufficiency. Twenty-four normal hearts served as controls. The two groups of hearts came from victims of homicide, suicide, accident, or natural death. Sections of the mitral valve, working myocardium, conduction system, and cardiac nerves and ganglia were studied by routine and special connective tissue and proteoglycan stains. Similar to the findings in severely affected mitral valves, prominent deposits of proteoglycans in neural and conduction tissue readily distinguished hearts with myxomatous valve changes from the control hearts. We conclude that the commonly recognized local derangement of valvular tissue in MVP is but one specific reflection of a more general myxomatous alteration in cardiac connective tissue.

Adolescent↗
PubMed1992

Synthesis and secretion of retinol-binding protein by cultured rat Sertoli cells.

We report here that retinol-binding protein (RBP) is synthesized and secreted by rat Sertoli cells in culture. This was demonstrated in four ways. First, transthyretin (TTR) bound to Sepharose 4B retained a labeled protein from media collected from Sertoli cells provided with 35S-methionine, under the same conditions as authentic RBP is bound. The protein was co-eluted with authentic RBP by pure water. Second, this same radioactive protein co-eluted with pure RBP upon gel filtration. Third, when subjected to SDS-PAGE, the protein again migrated with pure RBP, as shown by radioautography. Finally, Sertoli cells were incubated with 35S-cysteine and the conditioned medium was put over a TTR-Sepharose column to isolate the radioactive protein, as characterized above. Cysteine residues were oxidized to cysteic acid residues, and the protein was submitted for sequencing through the first ten residues. Radioactivity was located only in the fourth residue, where a cysteine residue is found in rat RBP. This indicates that RBP is secreted by the Sertoli cell and may serve as the carrier of retinol to the developing germ cells, which are known to be dependent upon vitamin A.

Amino Acid Sequence↗
PubMed1992

The application of the Screening Cerebral Assessment of Neppe (BROCAS SCAN) to a neuropsychiatric population.

Assessments of higher cortical functioning are often neglected in patients with possible coarse neurobehavioral psychiatric disease, such as dementia, stroke, or focal cerebral lesions. When performed, the short Folstein Mini-Mental State Exam (MMSE) is typically used. The authors' research on 45 neuropsychiatric patients compared the MMSE with a new 20-30-minute bedside examination, the Screening Cerebral Assessment of Neppe (BROCAS SCAN). This screens 10 areas: recall, recognition, orientation, organization of thought, concentration, calculation, agnosia, apraxia, speech, and sensory-motor-reflex phenomena. The BROCAS SCAN (total) correlated extremely well with neuropsychiatric prediction, MRI changes, and neuropsychological testing, and distinguished diagnoses, demonstrating construct and face validity. It also accounted for a larger proportion of variance than the MMSE in correlating with these parameters and was more sensitive in mildly cognitive impaired patients. The briefer first section of the BROCAS SCAN, the core SCAN, also showed statistically relevant relationships to age, diagnosis, MRI, and neuropsychiatric prediction.

Adolescent↗