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Biomedical subjects

A Keller

Publications and source records attributed to A Keller.

At least 127 records · Page 7Linked to original sources
PubMed1995

Comparison of the treatment effects of ossein-hydroxyapatite compound and calcium carbonate in osteoporotic females.

The aim of the study was to evaluate whether ossein-hydroxyapatite (OHC) is more effective than calcium carbonate (CC) in preventing further bone loss in postmenopausal osteoporosis. Forty osteoporotic patients were monitored for 20 months. The patients were randomly assigned to one of two groups and treated in a double-masked manner with 1400 mg calcium per day, in the form of either OHC or CC. OHC consists of hydroxyapatite, collagens and non-collagenous proteins/peptides containing insulin-like growth factor I (IGF-I; 1341 ng), insulin-like growth factor II (IGF-II; 670 ng), transforming growth factor beta (TGF-beta; 166 ng) and osteocalcin (47 micrograms). The bone densities were evaluated at intervals of 4 months with high-precision peripheral quantitative computed tomography. After 20 months of treatment the loss of trabecular bone was 0.8 +/- 0.5% in the OHC group and 1.8 +/- 0.7% in the CC group. The difference between the OHC and CC groups was statistically significant. This study shows that OHC is more effective than CC in slowing peripheral trabecular bone loss in patients with manifest osteoporosis.

Aged↗
PubMed1995

The management of gunshot fractures of the humerus.

We report 37 patients who were treated for gunshot fractures of the humerus during a 6 month period at the ICRC hospital, Lopiding, on the Sudanese border. Initial treatment followed the established principals for war surgery. The strategy for fracture stabilization however remains controversial. External fixation has been widely used in war surgery. This paper compares the different methods of stabilization for humeral fractures available in a field hospital. Fracture healing was delayed after external fixation and infection persisted longer than with the other methods of immobilization such as skeletal traction, functional bracing and 'collar and cuff' support. In the author's experience, external fixation has no advantage over non-operative methods for comminuted gunshot fractures of the humerus, unlike its use on the lower limb. The best results for fracture healing and final function were achieved by functional bracing.

Adolescent↗
PubMed1995

Long-term evaluation of patients undergoing immediate mandibular reconstruction.

BACKGROUND: Immediate reconstruction following segmental mandibulectomy is an accepted surgical technique. The benefits and patient selection criteria need to be established. PATIENTS AND METHODS: Forty-seven patients who underwent immediate reconstruction of the mandible were followed for up to 14 years. Survival, complication rates, and functional results were analyzed. RESULTS: Median survival was 39 months and actuarial 5-year survival was 40%. Two patients died in the postoperative period, and 9 suffered major reconstruction-related complications. The majority of these complications were related to the use of reconstruction plates, and occurred when the mandibular defect included the arch or when the plates were covered by pectoralis flaps. Half of the patients interviewed were able to eat a regular diet. CONCLUSIONS: Mandibular reconstruction can be performed safely and expeditiously in nearly all patients undergoing segmental mandibulectomy. Functional results and long-term survival will be acceptable in many cases.

Actuarial Analysis↗
PubMed1995

Concentrations of prolactin and prostaglandins during and after cardiopulmonary resuscitation.

OBJECTIVES: To assess differences in plasma prolactin and prostaglandin concentrations in resuscitated and nonresuscitated patients during cardiopulmonary resuscitation (CPR), and to compare changes of prostaglandin and prolactin concentrations with hemodynamic variables in the immediate postresuscitation phase. DESIGN: Prospective, descriptive study. SETTING: Emergency medical service at a university hospital. PATIENTS: Twenty-nine patients ranging in age from 39 to 87 yrs with out-of-hospital cardiac arrest. INTERVENTIONS: Venous blood samples were taken during CPR and at 5, 15, 30, and 60 mins after restoration of spontaneous circulation in order to measure plasma concentrations of prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 by immunoassay. Heart rate and blood pressure were measured at 5, 15, 30, and 60 mins after restoration of spontaneous circulation. MEASUREMENTS AND MAIN RESULTS: In 15 patients, restoration of spontaneous circulation was achieved; in the remaining 14 patients, successful resuscitation was not possible. During CPR, the mean plasma prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 concentrations were 95.9 +/- 13.6 micrograms/L, 357 +/- 61 ng/L, 228 +/- 28 ng/L, 277 +/- 66 ng/L, and 375 +/- 78 ng/L, respectively, in resuscitated patients, and 23.9 +/- 5.6 micrograms/L (p = .0001), 192 +/- 22 ng/L (p = .005), 202 +/- 31 ng/L (p = .528), 221 +/- 40 ng/L (p = .713), and 344 +/- 77 ng/L (p = .780), respectively, in nonresuscitated patients. At 60 mins after restoration of spontaneous circulation, the mean plasma prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 concentrations were 50.1 +/- 9.5 micrograms/L, 306 +/- 42 ng/L, 503 +/- 87 ng/L, 278 +/- 55 ng/L, and 355 +/- 30 ng/L, respectively. Mean values of systolic arterial blood pressure were 114 +/- 12 mm Hg at 30 mins and 123 +/- 18 mm Hg at 60 mins. No significant correlations were found between hemodynamic values and plasma concentrations of prolactin or prostaglandins. CONCLUSIONS: Prolactin and prostaglandin concentrations were increased during cardiac arrest and CPR. Successful initial resuscitation was associated with increased prolactin and prostaglandin F2 alpha concentrations during CPR. Decreased concentrations in non-resuscitated patients may have been a result of exhaustion of the neuroendocrine and eicosanoid systems, or may be due to differences in bioavailability at the site of blood sampling based upon differences in hemodynamics.

Adult↗
PubMed1995

Differential expression of alpha- and beta-enolase genes during rat heart development and hypertrophy.

We have analyzed the transition between isoforms of the glycolytic enzyme enolase (2-phospho-D-glycerate hydrolyase; EC 4.2.1.11) in rat heart during normal and pathological growth. A striking fall in embryonic alpha-enolase gene expression occurs during cardiac development, mostly controlled at pretranslational steps. In fetal and neonatal hearts, muscle-specific beta-enolase gene expression is a minor contributor to total enolase. Control mechanisms of beta-enolase gene expression must include posttranscriptional steps. Aortic stenosis induces a rapid and drastic decrease in beta-enolase transcript level in cardiomyocytes, followed by the fall in beta-subunit level. In contrast, alpha-enolase transcript level is not significantly altered, although the corresponding subunit level increases in nonmuscle cells. We conclude that, like fetal heart, hypertrophic heart is characterized by a high ratio of alpha- to beta-enolase subunit concentrations. This study indicates that the decrease in beta-enolase gene expression may be linked to beneficial energetic changes in contractile properties occurring during cardiac hypertrophy.

Aging↗
PubMed1995

Measurements of morning and evening airflow grossly underestimate the circadian variability of FEV1 and peak expiratory flow rate in asthma.

Peak expiratory flow rate (PEF) or forced expiratory volume in 1 s (FEV1) monitoring is an important clinical tool to assess the degree of 24-h variation (circadian) in lung function, which correlates with the degree of airway hyperresponsiveness. Ideally, PEF measurements should be taken frequently during the 24-h period to reflect the true variability. In practice, however, measurements are generally taken twice daily, usually upon arising and in the evening before bedtime. The effect of reducing the frequency of lung function measurement on the reported 24-h time average (mesor) and the circadian variability were evaluated. Four measurements taken 8 h apart and two measurements derived upon arising and the other, either 12 h later or before retiring, were compared with the full 24-h lung function profile, which included thirteen 2-hourly measurements. Based on the data from a 24-h lung function study in 20 adult patients with asthma, the corresponding values were separately compared at baseline and under two theophylline treatments, one being administered twice daily and the other once daily. The results are as follows: Whereas the 24-h time average (mesor) is hardly effected by the reduced measurements schemes, variability was grossly underestimated. Only 60 to 80% of the actual variability is picked up in the case of the four 8-hourly measurements, and only 20 to 45% in the case of the two measurements. The loss of accuracy in assessing 24-h airflow variability has potentially important implications on clinical practice and the investigation of therapeutics in asthma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Periodogram analysis for signal and noise evaluation in roentgen video signals].

Movements of the heart, the large vessels and the gastrointestinal tract can be evaluated for diagnostic purposes using fluoroscopic video systems. A new means of quantitatively evaluating the signal and noise components of the video signal is described. The signal and noise power components are determined from the periodogram after prior Fourier analysis. Variance is reduced by averaging and keeping the measuring conditions constant. For measurements of signal transfer properties, a radiological phantom capable of producing sinusoidal movements of the edge of the object was developed. An analysis of the performance of the theoretically derived evaluation parameters was carried out at a fluoroscopic unit under clinical conditions. Periodogram analysis makes possible objective image quality evaluation in clinical motion studies and in the technical quality assurance of fluoroscopic video systems. The use of a compact PC-based video measuring system renders application both practical and easy.

Artifacts↗
PubMed1995

Lacking effect of grapefruit juice on theophylline pharmacokinetics.

Grapefruit juice inhibits the biotransformation of several drugs, including caffeine (23% clearance reduction), which is metabolized by the cytochrome P450 isoform CYP1A2. Since CYP1A2 also participates in theophylline biotransformation, a randomized change-over study on a possible interaction between grapefruit juice and theophylline was conducted. Twelve healthy young male nonsmokers were included (median 26 (range 23-30) years, weight 73 (65-85) kg). Theophylline was given as a single dose of 200 mg in solution (Euphyllin 200), diluted by 100 ml of either water or grapefruit juice (751 mg/l naringin). Subsequently, additional fractionated 0.91 of water or juice were administered until 16 hours postdose. Theophylline concentrations in plasma withdrawn up to 24 hours postdose were measured by HPLC, and its pharmacokinetics were estimated using compartment model independent methods. To compare between the 2 treatments, ANOVA based point estimates and 90% confidence intervals (given in parentheses) were calculated for the test (= grapefruit coadministration) to reference (= water coadministration) ratios (Tmax: differences). These were: Cmax 0.90 (0.81-1.00), AUC 1.02 (0.95-1.11), Cmax/AUC 0.88 (0.81-0.95), T 1/2el 1.03 (0.98-1.09), Tmax 0.15 h (-0.11h-0.41 h). Thus, no pharmacokinetic interaction between grapefruit juice and theophylline was observed. This finding is in contrast to the effect of grapefruit juice reported on caffeine metabolism and may be due to the contribution of enzymes other than CYP1A2 to primary theophylline metabolism or to differences in naringin and/or naringenin kinetics between studies.

Absorption↗
PubMed1995

[Pharmacokinetics of a theophylline effervescent tablet].

The theophylline effervescent tablet (Euphyllin quick 200) provides a new acute medication for the treatment of pulmonary obstructive lung diseases. Its pharmacokinetics were determined in 12 healthy male volunteers and compared in a single-dose crossover study to those after administration of an oral solution (Euphyllin 200 ampoule). Based on the primary pharmacokinetic characteristics for rate and extent of absorption, Cmax and AUC, both formulations were bioequivalent.

Adult↗
PubMed1995

[Metal-based esthetic inlays].

The aesthetic appearance and marginal accuracy of porcelain fused to metal inlays/onlays have been evaluated in this study. The metal frameworks of the restorations were fabricated by casting or by galvanic techniques. Both the gold collar and the insufficient thickness of covering porcelain influenced the aesthetic features of inlays negatively. The good aesthetic appearance achieved in case of onlays was independent of manufacturing procedures. Inlays/onlays accomplished by galvanic technique showed a better marginal fitting as compared to that of cast ones.

Adult↗
PubMed1994

Intravenous pamidronate disodium treatment of bone metastases in patients with breast cancer. A dose-seeking study.

BACKGROUND: Treatment of the symptoms of bone metastases currently involves the use of narcotic medication, radiation therapy, or hormonal therapy. Pamidronate disodium, a bisphosphonate, may prove helpful in the palliative treatment of bone metastases in patients with breast cancer as demonstrated in this multicenter, dose-ranging trial. METHODS: Ambulatory female patients age 18 years or older with breast cancer metastatic to bone and a life expectancy of at least 3 months were eligible for the study. Bone metastases were confirmed by bone scan or bone survey within 6 months of enrollment. Sixty-one patients were treated as outpatients and were randomized to receive one of four intravenous pamidronate regimens for 12 weeks: 30 mg administered every 2 weeks, 60 mg every 4 weeks, 60 mg every 2 weeks, or 90 mg every 4 weeks. The primary efficacy parameter for this study was pain score. The change from baseline in pain score was determined for each patient at each study visit and at endpoint, defined as the last postbaseline evaluation for each patient before or at week 12. Secondary efficacy variables included narcotic scores, urinary calcium/creatinine and hydroxyproline/creatinine ratios, serum osteocalcin and bone alkaline phosphatase concentrations, and bone lesion (radiologic) response. RESULTS: At 3 months, the regimens of 60 mg every 4 weeks, 60 mg every 2 weeks, and 90 mg every 4 weeks resulted in significant reduction in bone pain beginning by week 6 of treatment. The regimen of 30 mg every 2 weeks was not effective. Narcotic use, as reflected by narcotic scores, did not parallel the pain scores, because there was little evidence of any effect for any of the treatment groups. Reduction in bone pain was accompanied by decreases in urinary calcium/creatinine and hydroxyproline/creatinine ratios, and bone alkaline phosphatase concentrations. Side effects of pamidronate were mild and transient. Radiographic changes consistent with healing of lytic lesions were observed in 15 patients (25%). CONCLUSION: Intravenous pamidronate is a well tolerated treatment that produced significant relief of bone pain in the majority of patients with metastatic breast cancer at the three highest doses tested.

Adolescent↗
PubMed1994

Coexpression of alpha and gamma enolase genes in neurons of adult rat brain.

Enolase (EC 4.2.1.11) is a glycolytic enzyme active as a dimer. In adult brain extracts, three forms, alpha alpha, alpha gamma and gamma gamma, have been described, with the alpha gamma hybrid accounting for 30% of total enolase activity (Fletcher et al., Dev Biol 65:462-475, 1978; Lucas et al., Dev Neurosci 10:91-98, 1988). Previous biochemical studies strongly suggest that this hybrid is not generated artefactually during the extraction procedures (Keller et al., J Neurochem 36:1389-1397, 1981; Shimizu et al., BBA 748:278-284, 1983). Immunocytological observations have demonstrated the cell specific localization of the alpha subunit in astrocytes and of the gamma subunit in neurons at the adult stage, but failed to identify a cell type containing both the alpha and gamma subunits necessary for the formation of the alpha gamma hybrid isoform (Ghandour et al., Exp Brain Res 41:271-279, 1981; Vinores et al., J Histochem Cytochem 32:1295-1302, 1984; Iwanaga et al., Arch Histol Cytol [Suppl] 52:13-24, 1989). We sought to approach this question by performing in situ hybridization studies in order to visualize the alpha and gamma mRNAs. In agreement with the immunocytological reports, we observe a specific accumulation of the gamma enolase transcripts in neurons and a high accumulation of alpha enolase transcripts in some glial cells such as the ependymocytes lining the ventricles. Our observations, following hybridization with 35S labeled oligonucleotide specific probes on adjacent thin sections, demonstrate for the first time that transcription of both alpha and gamma enolase genes occurs in many neurons of different brain regions. These results render highly probable the formation of the alpha gamma hybrid in mature neurons. Furthermore, we observe a differential expression of the genes encoding the alpha and gamma enolase subunits in various neuronal populations of the brain. The implications of these observations are discussed.

Animals↗
PubMed1994

[Problems with bone densitometry].

Today, bone density can be measured by different technical methods which show variations in terms of reproducibility, accuracy and sensibility. A crucial parameter is the reproducibility, which differs considerably from method to method. With densitometric methods it is possible not only to evaluate patients at risk getting an osteoporosis but also to establish an individual prophylaxis and therapy by means of highly precise quantitative methods, based on the parameters 'bone density' and 'loss of bone density'. A high bone turnover leads to fast bone loss and, vice versa, fast bone loss, measured by densitometry, is correlated with high bone turnover in postmenopausal women. This allows to establish an individual therapy with antiresorption resp. bone-stimulating agents and the knowledge about a tailored, individual treatment increases patients' compliance and reduces the rate of 'non-responders'.

Aged↗