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Biomedical subjects

C A Hansen

Publications and source records attributed to C A Hansen.

At least 73 records · Page 4Linked to original sources
PubMed1986

Nuclear magnetic resonance spectroscopic analysis of myo-inositol phosphates including inositol 1,3,4,5-tetrakisphosphate.

1H and 31P NMR spectra of a variety of phosphorylated myo-inositols have been analyzed using a Bruker WH-360 spectrometer. Proton and phosphorus chemical shifts and coupling constants are reported for myo-inositol 1-phosphate, myo-inositol 2-phosphate, myo-inositol 5-phosphate, myo-inositol 1,2-cyclic phosphate, myo-inositol 1,4-bisphosphate, myo-inositol 1,4,5-trisphosphate, and myo-inositol 1,3,4,5-tetrakisphosphate. These data provide the basis for the chemical identification and characterization of biologically relevant inositol phosphates.

Hydrogen↗
PubMed1986

Formation and metabolism of inositol 1,3,4,5-tetrakisphosphate in liver.

The inositol lipid pools of isolated rat hepatocytes were labeled with [3H]myo-inositol, stimulated maximally with vasopressin and the relative contents of [3H]inositol phosphates were measured by high performance liquid chromatography. Inositol 1,4,5-trisphosphate accumulated rapidly (peak 20 s), while inositol 1,3,4-trisphosphate and a novel inositol phosphate (ascribed to inositol 1,3,4,5-tetrakisphosphate) accumulated at a slower rate over 2 min. Incubation of hepatocytes with 10 mM Li+ prior to vasopressin addition selectively augmented the levels of inositol monophosphate, inositol 1,4-bisphosphate, and inositol 1,3,4-trisphosphate. A kinase was partially purified from liver and brain cortex which catalyzed an ATP-dependent phosphorylation of [3H]inositol 1,4,5-trisphosphate to inositol 1,3,4,5-tetrakisphosphate. Incubation of purified [3H]inositol 1,3,4,5-tetrakisphosphate with diluted liver homogenate produced initially inositol 1,3,4-trisphosphate and subsequently inositol 1,3-bisphosphate, the formation of which could be inhibited by Li+. The data demonstrate that the most probable pathway for the formation of inositol 1,3,4,5-tetrakisphosphate is by 3-phosphorylation of inositol 1,4,5-trisphosphate by a soluble mammalian kinase. Degradation of both compounds occurs first by a Li+-insensitive 5-phosphatase and subsequently by a Li+-sensitive 4-phosphatase. The prolonged accumulation of both inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate in vasopressin-stimulated hepatocytes suggest that they have separate second messenger roles, perhaps both relating to Ca2+-signalling events.

Animals↗
PubMed1986

Pin-modified facial inlay to enhance retentive contours on a removable partial denture abutment.

A procedure has been described that will, in many instances, eliminate the necessity for a full veneer crown. The periodontal health of the tooth is not compromised because the accentuated contour is generally remote from the gingival tissues. A single pin will assure sufficient retention and resistance to displacement for the small inlay if the walls of the preparation offer reasonable resistance form.

Dental Abutments↗
PubMed1986

An esthetic removable partial denture retainer for the maxillary canine.

The use of a distofacial ridge on a maxillary canine abutment for a distal-extension base of a removable partial denture is described. The distofacial ridge will permit the placement of a less conspicuous I-bar arm on the distofacial surface of the tooth. The ridge provides bracing against distal movement during function and thus prevents the subsequent loss of retention for the prosthesis. It also permits a more precise path of insertion and withdrawal for the prosthesis. Three methods of establishing a distofacial ridge on a canine abutment are described.

Composite Resins↗
PubMed1986

Fatty acid metabolism in hearts containing elevated levels of CoA.

Palmitate metabolism was determined in isolated perfused hearts containing elevated levels of coenzyme A (CoA). CoA levels were elevated by perfusing hearts with Krebs-Henseleit buffer containing 0.1 mM cysteine, 0.2 mM dithiothreitol, 15 microM pantothenic acid, and no energy substrate. After 45 min, CoA levels had increased from 537 +/- 14 to 818 +/- 44 nmol/g dry wt. When these hearts containing high CoA were subsequently perfused as working hearts with buffer containing 11 mM glucose and 1.2 mM palmitate, long chain acyl CoA levels increased (94 +/- 5-305 +/- 6 nmol/g dry wt). Oxidation of exogenous palmitate (as measured by 14CO2 production from [U-14C]palmitate) was significantly depressed in hearts containing elevated CoA levels. This apparent reduction in fatty acid oxidation was not due to increased glucose or glycogen utilization. When the concentration of palmitate was decreased to 0.4 mM, acyl CoA levels increased much less, and the apparent rate of [14C]palmitate oxidation was unaffected by elevated CoA. Hearts containing high CoA also incorporated [14C]palmitate into triacylglycerols to a greater extent than did control hearts. To determine whether the apparent decrease in exogenous palmitate oxidation resulted from an increased utilization of unlabeled endogenous triacylglycerol fatty acid, [14C]palmitate specific activity was measured in myocardial acylcarnitine. The specific activity of this pool of fatty acid was similar in both control hearts and hearts containing elevated CoA. Thus dilution of the total cellular [14C]acyl carnitine by triacylglycerol hydrolysis was not sufficient to account for the decrease in [U-14C]palmitate oxidation. The possibility that a small pool of rapidly turning over acyl carnitine becomes dilated is discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Metabolic rates in normal and infarcted myocardium.

The effects of myocardial infarction in rat hearts on the utilization of fatty acids and glucose by the surviving, non-infarcted tissue were studied. Hearts were removed from the animals one-week post-infarcted and perfused in the isolated working heart preparation. Oxygen consumption and oxidation of palmitate and glucose were determined at two levels of cardiac work. Rates of substrate oxidation were estimated by 14CO2 production from [14C]-labeled substrates. This approach to measuring metabolic rates may seriously under-estimate the true oxidative rate particularly when measuring oxidation of long-chain fatty acids. Because of the large endogenous stores of fatty acids in tissue lipids, the [14C]-specific activity of the intracellular metabolites involved in the free fatty acids oxidation pathway do not equilibrate with the specific activity of the perfusate fatty acids oxidation pathway do not equilibrate with the specific activity of the perfusate fatty acid even when 14CO2 production has reached an apparent steady state. When comparing an experimental condition to the normal heart, a lower rate of 14CO2 production may not necessarily indicate a lower rate of oxidation of free fatty acids, but a difference in the rate of turnover of endogenous sources of unlabeled fatty acid such that the specific activity of intracellular metabolites equilibrate with extracellular labeled substrate to a lesser extent than in the normal heart. At physiological concentrations of fatty acids, a shift from fatty acid to carbohydrate oxidation occurred in the hypertrophied, surviving tissue following myocardial infarction in the rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Diagnostically restoring a reduced occlusal vertical dimension without permanently altering the existing dentures.

The technique described provides the dentist with a means of diagnostically restoring the vertical dimension of occlusion for an edentulous patient, without permanently altering the dentures. This procedure is accomplished with a removable mandibular splint, which snaps over the mandibular denture. The procedure involves little clinical treatment time. The maxillary denture may also be temporarily overlayed in a similar manner, but the procedure is generally not as esthetically acceptable. Since the mandibular alveolar bone resorbs much faster than that of the maxillae in most edentulous patients, the mandibular denture usually is responsible for most of the loss of occlusal vertical dimension. The mandibular denture is therefore most frequently indicated for alteration to restore lost occlusal vertical dimension. Medicolegal implications, as well as practical considerations, suggest that the patient's present dentures should not be permanently altered before new dentures are found to be satisfactory.

Dental Impression Technique↗
PubMed1985

Clinical comparison of two mandibular major connector designs: the sublingual bar and the lingual plate.

Two mandibular removable partial dentures, one with a sublingual bar and one with a lingual plate as the major connector, were constructed for 10 patients. Both were made using the same impression and were identical except for the design of the major connector. The two major connector designs were evaluated by the patients at the conclusion of the study. Eight of the 10 patients preferred the lingual plate and nine of the 10 found both designs satisfactory. One patient indicated a strong preference for the sublingual bar over the lingual plate and another found both designs equally acceptable. We have concluded from the final data that the sublingual bar compares favorably with the lingual plate in patient acceptance and should be considered as a viable design alternative when a lingual plate is not indicated.

Consumer Behavior↗
PubMed1985

Metal minibases in removable prosthodontics.

A description of the designs and indications for minibases in removable prosthodontics has been presented. Minibases can solve complicated space problems when surgery is contraindicated by providing a strong, thin, abrasive-resistant denture base. The result of their correct use is a prosthesis that fits well, is extended correctly, functions without opposing interferences at the correct vertical dimension of occlusion, and resists the functional stresses placed on it during service.

Dental Alloys↗
PubMed1985

Chronic infarction decreases maximum cardiac work and sensitivity of heart to extracellular calcium.

Rat hearts were infarcted in vivo by ligation of the left ventricular coronary artery to cause an initial 40% loss of viable tissue by weight. Due to compensatory hypertrophy of the surviving myocardium and progression of the infarct to scar tissue, the infarct represented approximately 25% by weight of the whole heart after 1 wk. After 1 or 3 wk, these infarcted hearts were removed and perfused in vitro by the working hearts technique. Ventricular pressure development and positive dP/dt were lower in infarcted hearts compared with sham-operated ones. O2 consumption and glucose utilization by viable tissue per unit pressure development was the same in normal and infarcted hearts. Levels of creatine phosphate and free creatine were decreased, but ATP and total adenine nucleotides were well maintained. The inotropic response to decreases in extracellular [Ca2+] was much greater in infarcted hearts than in sham controls. Prenalterol increased ventricular function proportionally more in infarcted than in the sham-operated hearts, suggesting that down regulation of beta receptors was not a problem. The infarcted hearts were much more sensitive to verapamil than control hearts. It is concluded that the depressed function of the noninfarcted tissue of chronically infarcted hearts is due in part to loss of functioning tissue mass and in part to decreased sensitivity to extracellular Ca2+.

Adenosine Triphosphate↗
PubMed1985

Magnesium sulfate and beta-mimetic dual-agent tocolysis in preterm labor after single-agent failure.

Twenty-three patients in preterm labor failed to respond to single-agent tocolytic therapy or could not tolerate the dosage necessary to inhibit contractions. A combination of magnesium sulfate and ritodrine or terbutaline was used to inhibit labor in these patients. Fourteen patients (60.9%) responded to dual-agent tocolysis by delaying delivery for 48 hours or more. Six patients had delivery delayed for more than one week. Five patients had multiple gestations; three of them had delivery delayed more than 48 hours. Five patients developed pulmonary edema under treatment with dual-agent tocolysis; all responded to diuretic and/or oxygen therapy after the termination of tocolysis. Dual-agent tocolysis may significantly prolong some pregnancies complicated by preterm labor, but only at some risk to maternal well-being.

Adrenergic beta-Agonists↗
PubMed1983

Atlantic hagfish cardiac muscle: metabolic basis of tolerance to anoxia.

Oxygen tensions in the major venous inputs to the systemic and portal-vein hearts of normoxic Atlantic hagfish (12.3 +/- 1.7 and 11.0 +/- 1.6 mmHg, respectively) are low compared with typical vertebrate values. Anoxia and poisoning with cyanide and azide do not significantly affect in situ performance of the systemic heart. Idoacetate poisoning, however, results in a significant decrease in cardiac performance of the systemic heart to 12% of the initial value after 3 h. Activities of mitochondrial enzymes of hagfish ventricle suggest a small potential for aerobic metabolism compared with those in the aerobic ventricle of Atlantic cod. Activities of enzymes of carbohydrate metabolism indicate similar anaerobic capacity in hagfish and cod ventricle. The ratio of pyruvate kinase to cytochrome c oxidase, an index of anaerobic to aerobic capacity, is 5.6 times greater in hagfish than cod ventricle. Metabolite concentrations in freeze-clamped ventricles of normoxic and hypoxic hagfish indicate hypoxia-induced activation of glycogenolysis, enhanced substrate flow across 6-phosphofructokinase, and an apparent secondary constriction of glycolysis at the level of glyceraldehyde-phosphate dehydrogenase. Carbohydrate utilization via the glycolytic pathway appears essential for maintenance of cardiac performance in both normoxic and anoxic hagfish. Under conditions of severe hypoxia, ATP provision is probably met by anaerobic glycolysis.

Alcohol Oxidoreductases↗
PubMed1977

Trisomy 22 with 'cat eye' anomaly.

The case of a 10-month-old girl with an extra G-like chromosome is presented. Quinacrine, trypsin-Giemsa, and reverse banding identified the extra chromosome as no. 22. The phenotype of the patient is unique in that unilateral iris coloboma was observed, unlike the 18 cases of full trisomy 22 already published. This represents the first reported case of full trisomy 22 with this coloboma, or 'cat eye' anomaly, which is usually associated with partial trisomy 22. It is suggested that the use of the term 'cat eye syndrome' be revised. The terms 'partial trisomy 22 syndrome' and 'trisomy 22 syndrome' should be used instead.

Azure Stains↗