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Biomedical subjects

C Berg

Publications and source records attributed to C Berg.

At least 127 records · Page 7Linked to original sources
PubMed1987

MDL 72567, a dihydropyridine calcium-antagonist, that causes vasodilation and direct sinus bradycardia.

MDL 72567 (2,6 dimethyl,3 methoxycarbonyl,4-(2-nitrophenyl), 5-(2-furoyl)1,4 dihydropyridine) was a potent antagonist of Ca2+-induced contractions in K+-depolarized taenia preparations from the guinea pig caecum (pA2 8.8 +/- 0.1). MDL 72567 was a potent displacer of [3H]nitrendipine binding from rat cortical membrane preparations (Ki 3.99 nM), indicating an effect at the dihydropyridine binding site, which is consistent with the finding that the inhibitory effects of MDL 72567 in smooth muscle were prevented by the dihydropyridine Ca2+ channel activator Bay K 8644. MDL 72567 slowed spontaneously beating rat atria preparations to a greater extent than did nifedipine, however, for a given negative inotropic effect. Furthermore, in pithed rat preparations infused with angiotensin II to elevate blood pressure, the hypotensive effects of MDL 72567 (3 nmol/kg-3 mumol/kg, intravenously, i.v.) were accompanied by bradycardia, whereas nifedipine, PY 108-068, and nicardipine lowered blood pressure without affecting heart rate. When compared with nifedipine, MDL 72567 caused less reflex tachycardia for a given fall in blood pressure, in anesthetized beagles and in conscious renal hypertensive dogs. In anesthetized dogs, MDL 72567 increased cardiac contractility at all hypotensive doses tested (30-3,000 nmol/kg, i.v.), whereas nifedipine caused profound myocardial depression at higher doses (1,000-3,000 nmol/kg, i.v.) even though the compounds had equivalent vasodilator effects. Thus, although MDL 72567 appears to cause a direct myocardial slowing that can partially offset reflex tachycardia, the compound has negligible negative inotropic effects and may therefore be useful in angina pectoris or even in congestive heart failure.

Animals↗
PubMed1987

The composition of four-hour urine samples from patients with calcium oxalate stone disease.

Urine collected during a 24-h period between 06.00 and 10.00 h from 25 patients with recurrent CaOx stone disease was analysed with respect to calcium, oxalate, magnesium, citrate and creatinine. Urinary excretion of oxalate in relation to creatinine was slightly higher in 24-h urine but the correlation between 24-h and 4-h values was good. Good correlations were also recorded for calcium and citrate, whereas a more variable result was obtained for magnesium. In terms of the risk of forming a supersaturated urine (CaOx risk index), a good correlation was observed between 24-h and 4-h urine samples, although the highest values were found in 24-h urine. As a result of a low mean urine flow between 06.00 and 10.00 h, the highest supersaturation in terms of the AP (CaOx) index was observed in these samples. When the risk of calcium oxalate crystallisation (CaOx-CR) was determined by means of the increment in oxalate concentration required for precipitation of CaOx, 7 of 11 samples had the highest values in the 4-h urine. Samples collected during a 4-h period might thus be useful in the evaluation and follow-up of CaOx stone formers and further studies will show to what extent they can replace 24-h urine collections.

Calcium↗
PubMed1986

Phase I combined modality clinical trial of alpha-2-interferon and radiotherapy.

Sixteen patients were enrolled in a Phase I study of the combined use of recombinant DNA alpha-2-interferon (IFN) and radiation therapy, conducted at the Georgetown University Hospital (GUH) from February 1, 1984 to September 20, 1985. Escalating IFN doses ranging from 2.0 X 10(6) IU/m2 to 5 X 10(6) IU/m2 were administered to groups of six patients per IFN dose level. Three patients at each dose level were treated on a 5-day-a-week schedule and three patients were treated on a 3-day-a-week schedule. Significant toxicity including dehydration, infection, deep vein thrombosis, and myocardial infarction was noted throughout in patients receiving IFN five times per week, with eight of nine requiring hospitalization during the treatment course. There was one treatment-related death. In the five-times-per-week group, only 22% of patients tolerated the full initially planned IFN dosage and 44% tolerated the full initially planned radiation dosage, compared to 100 and 86%, respectively, in the three-times-per-week group. A tolerance dose and schedule of 5.0 X 10(6) IU/m2 of alpha-2-interferon administered subcutaneously three-times-per-week in conjunction with standard radiotherapy has been identified for use in future combined modality trials.

Combined Modality Therapy↗
PubMed1986

The effect of pH on the risk of calcium oxalate crystallization in urine.

The risk of calcium oxalate (CaOx) crystallization at different pH levels was determined in urine from recurrent CaOx-stone formers and normal subjects. The highest crystallization risk was observed between pH 4.5 and 5.5. In the pH range 6.5-7.5, there was a marked increase in crystallization of calcium phosphate (CaP). The results suggest the beneficial effect of moderate alkalinization in terms of a reduced CaOx crystallization. Reduced CaOx crystallization occurs at the expense of an increased formation of CaP crystals. Whether this increases the risk of CaP-stone formation is not known, but the CaP crystals were usually small, at least below pH 7.5.

Calcium↗
PubMed1986

Aqueous and serum-based materials compared for use as simulated calibrators for three ionized calcium analyzers.

To determine if bias between different ionized calcium analyzers could be decreased, we analyzed 10 control fluids during a study in which ionized calcium was measured in more than 150 serum and whole-blood samples. After calibrating three ionized calcium analyzers (Radiometer ICA 1, Nova 8, and AVL 980) with the manufacturers' respective calibrators, we used the between-instrument differences of the control fluids to simulate recalibration of the analyzers during each analytical run. A filtered human serum pool containing ionized calcium at 1 mmol/L concentration, with CO2 removed and having no added buffer, was the only material that consistently decreased between-analyzer bias of both serum and whole blood. Another human serum pool containing about 1.3 mmol of ionized calcium and about 10 mmol of bicarbonate per liter was even better at minimizing analyzer biases for serum samples, but was not as effective for whole-blood samples. Some additives used to buffer pH apparently adversely affected both the accuracy and precision of some, but not other, calcium ion electrodes. We conclude that if a reference material is developed for calibration of ionized calcium analyzers, it should be tested on several analyzers for use with both serum and whole blood, and it should be at least as effective as a human serum material, such as that used here.

Calcium↗
PubMed1986

The combined use of interferon and radiotherapy in cancer management.

Preclinical studies have suggested combination therapy with interferon and radiation results in an enhanced cytotoxic effect. Both additive and synergistic effects have been reported in mammalian cells in tissue culture. A phase I trial was designed to determine patient tolerance to concomitant Schering interferon alfa-2b (Intron A) and radiation therapy (RT). RT was delivered in standard fashion (five times a week in 180 rad fractions). Interferon was injected subcutaneously 2 hours prior to irradiation. Sixteen patients, divided into groups of three, received interferon at dose levels of 2 X 10(6) to 30 X 10(6) IU/m2 given five or three times a week. Planned dose escalations were stopped at 5 X 10(6) IU/m2 by patient tolerance. We observed a significant difference in tolerance to treatment between the patients receiving interferon three times a week and those receiving interferon five times a week. Eight of nine patients treated five times a week developed grade III-IV toxicity resulting in hospitalization and discontinuation of interferon; radiation was not discontinued. Only two of seven patients treated three times a week were hospitalized, with grade II toxicity (anorexia), but both were subsequently able to continue treatment with both interferon and radiation. We have identified a maximum tolerated dose and schedule of interferon (5 X 10(6) IU/m2 three times a week) for use in future combined modality trials to assess the potential clinical effectiveness of interferon in combination with RT.

Adult↗
PubMed1985

Antagonism of Ca2+-induced contractions of K+-depolarized smooth muscle by local anaesthetics.

Drugs known to interact with Na+ channels were compared as antagonists of Ca2+-induced contractions of K+-depolarized taenia preparations from guinea-pig caecum. Tetracaine (apparent pA2 5.3 +/- 0.2), quinidine (5.2 +/- 0.1) quinine (5.1 +/- 0.1), d-propranolol (4.7 +/- 0.1), 1-propranolol (4.7 +/- 0.1), lignocaine (4.0 +/- 0.1) and procaine (3.6 +/- 0.1) displaced cumulative concentration-response curves to Ca2+ to the right without depression the maximal response. The slopes of Arunlakshana and Schild plots were close to unity for quinidine, quinine, lignocaine and procaine. These drugs relaxed the established Ca2+-induced contractions rapidly and thus the effects of these drugs resembled the effects of low concentrations of verapamil. However, the effects of the local anaesthetics were increased in the presence of sodium salicylate (5-10 mM) which increases the negative surface charge. In contrast the effects of verapamil were decreased by salicylate. Veratridine (10-100 microM), which activates Na+ channels, had only depressant effects on Ca2+-induced contractions. Thus, drugs acting on Na+ channels can also interact with Ca2+ channels but there are qualitative as well as quantitative differences between the effects of these drugs and those of drugs such as verapamil. These findings indicate different mechanisms of action for the inhibition of Ca2+-induced contractions by local anaesthetics and verapamil.

Anesthetics, Local↗
PubMed1984

A screening protocol for a prenatal population at risk for inherited hemoglobin disorders: results of its application to a group of Southeast Asians and blacks.

Several inherited hemoglobin disorders are present among certain racial subgroups of the United States population, particularly among blacks and Southeast Asians. Many of these disorders are unfamiliar to the obstetrician-gynecologist but may have important implications for care in pregnancy, including genetic counseling and prenatal diagnosis. A simple, effective screening tool was devised for detection of thalassemias and hemoglobinopathies in a prenatal clinic population. Use of the tool resulted in diagnosis of a hemoglobin disorder in 20% of a group of black patients; diagnoses included alpha-thalassemia trait, beta-thalassemia trait, hemoglobin C trait, hemoglobin S/C disease, hemoglobin S trait, sickle cell anemia, and hemoglobin Lepore. In a group of Southeast Asian patients, 39% had a hemoglobin disorder, including alpha-thalassemia trait, beta-thalassemia trait, hemoglobin E disease, and hemoglobin H disease. Implications for care are discussed.

Asia, Southeastern↗
PubMed1984

Interactions between a "calcium channel agonist", Bay K 8644, and calcium antagonists differentiate calcium antagonist subgroups in K+-depolarized smooth muscle.

The proposal that calcium antagonists have different sites of action has been tested by attempting to reverse their inhibitory effects with a dihydropyridine which augments Ca2+ entry into cells, Bay K 8644. Bay K 8644 (1-1000 nmol/l) increased the sensitivity to Ca2+ of K+-depolarized taenia preparations from the guinea-pig caecum. Thus Bay K 8644 augmented established submaximal Ca2+-induced contractions and also shifted cumulative concentration-response curves to Ca2+ to the left, even in the presence of an optimal K+-depolarization. The inhibitory effects of nifedipine (10 nmol/l), verapamil (0.2 mumol/l), diltiazem (1 mumol/l) and diclofurime (1 mumol/l) on Ca2+-induced contractions were reversed by Bay K 8644 (1-1000 nmol/l). In contrast, Bay K 8644 did not reverse the effects of cinnarizine (1 mumol/l), flunarizine (1 mumol/l), fendiline (3 mumol/l), prenylamine (3 mumol/l), pimozide (1 mumol/l), bepridil (3 mumol/l), perhexiline (10 mumol/l) or the calmodulin antagonist W-7 (200 mumol/l). Bay K 8644 (1-100 nmol/l) was less effective at reversing the effects of nisoldipine (10 nmol/l), a slowly dissociating dihydropyridine, than the effects of nifedipine. However, preincubation with Bay K 8644 (1 mumol/l) protected the taenia from the inhibitory effects of nisoldipine (10 nmol/l). These findings are compatible with interactions of nisoldipine and Bay K 8644 at a common site. Taenia preparations incubated with Bay K 8644 (1 mumol/l) were protected from the inhibitory effects of nifedipine (10 nmol/l), nisoldipine (10 nmol/l) and to a lesser extent verapamil (0.2 mumol/l) and diltiazem (1 mumol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1982

Structure and function of small ribonucleoproteins from eukaryotic cells.

Autoantibodies from patients with systemic lupus erythematosus and other related diseases have been used to identify and study small RNA-protein complexes from mammalian cells. Properties of three previously described and several new classes of small ribonucleoproteins (RNPs) are reviewed. The sequence of Drosophila U1 RNA reveals that the region proposed to pair with 5' splice junctions is conserved, while that proposed to interact with 3' junctions diverges; this forces some revision of the model for U1 small nuclear (sn)RNP participation in hnRNA splicing. Further characterization of the Ro and La small RNPs has shown that the Ro small cytoplasmic (sc)RNPs are a subclass of La RNPs. Both tRNA and 5S rRNA precursors are at least transiently associated with the La protein. This raises the possibility that the La protein may be an RNA polymerase III transcription factor.

Antigen-Antibody Complex↗
PubMed1977

Paget's disease.

Explore the source record for details and available documents.

Aged↗
PubMed1976

Alcoholics' perception of leisure.

The attitudes of alcoholics and a norm group toward leisure were compared. The alcoholics differed from the norm consistently in seeing themselves as having more leisure than they wanted, in being more work-oriented, in preferring highly structured free time, and in viewing leisure negatively.

Age Factors↗
PubMedDate not supplied

Factors associated with inadequate prenatal care during the second pregnancies among African-American women.

A longitudinally linked data set for Georgia was used to identify characteristics, including previous prenatal care use and complications at the first birth, associated with prenatal care use in the second pregnancy among 8,224 African-American women. More than 70% of the women who were < 25 years of age at their first birth (younger women) and almost 40% of women who were > or = 25 years at their first birth received inadequate care with at least one of their first two births. Women who received inadequate care in their first pregnancy were more likely to receive inadequate care in their second pregnancy than women who received adequate care in their first pregnancy. Younger women with a history of a stillbirth, neonatal death, or vacuum extraction were less likely to receive inadequate care in their subsequent pregnancy. Although this study was not able to evaluate the content of prenatal care, it suggested that many African-American women may not receive sufficient care to prevent adverse pregnancy outcomes. Women who receive inadequate care in their first pregnancy must be targeted for interventions that help them overcome economic, situational, or attitudinal barriers to receiving adequate care in their next pregnancy.

Adolescent↗