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Biomedical subjects

G Kreutz

Publications and source records attributed to G Kreutz.

At least 19 recordsLinked to original sources
PubMed2002

The use of placebo-controlled and non-inferiority trials for the evaluation of new drugs in the treatment of postmenopausal osteoporosis.

Registration of new agents for the treatment of postmenopausal osteoporosis has been based over the past few years on placebo-controlled phase III trials with the incidence of patients with new vertebral/nonvertebral fractures as the most usual primary endpoint. The use of a placebo in diseases where an active treatment is available has been a matter of debate following the update of the Declaration of Helsinki by the World Medical Association which questioned this trial design. Current regulatory recommendations within the European Union suggest that placebo-controlled trials are still the best option when assessing the efficacy and safety of new drugs intended for the treatment of postmenopausal osteoporosis. This suggestion seems to be in apparent contradiction with the current content of the Declaration of Helsinki. This paper addresses the ethics and feasibility of placebo-controlled trials in the treatment of postmenopausal osteoporosis, in the light of available therapeutic options, and discusses possible alternative approaches in those patients where placebo treatment could be deemed to be unethical. It is concluded that placebo-controlled trials remain the most efficient design to establish the efficacy and safety of a new agent for the treatment of postmenopausal osteoporosis. Such trials are feasible and ethically acceptable in patients with osteoporosis but without prevalent vertebral fractures. Conversely, in patients with prevalent vertebral fractures, placebo-controlled trials are ethically questionable and non-inferiority trials are more appropriate. A relative margin of non-inferiority of 20-30% is suggested, to be discussed on a case by case basis.

Aged↗
PubMed2000

Background for studies on the treatment of male osteoporosis: state of the art.

Male osteoporosis represents an important, although long underestimated, public health problem. Both in men and in women aging is accompanied by continuous bone loss and by an exponential increase in the incidence of osteoporotic fracture, with a female to male incidence ratio of about 2 to 3 to 1 in the elderly for hip and vertebral fractures. Morbidity after osteoporotic fractures appears to be more serious and mortality more common in men than in women. To date, no single treatment has been proved to be effective and safe in published prospective studies. The present report, based on a systematic search of the literature on male osteoporosis, summarises the state of the art on the clinical consequences of male osteoporosis and its risk factors, in relation to the present state of knowledge about female osteoporosis. This constitutes the background for the design of rational clinical development strategies for therapeutic interventions in male osteoporosis. From this review of the literature it is apparent that notwithstanding the existing sex differences in pathophysiology of osteoporosis and the difference in age-specific incidence of osteoporotic fractures, there are also important similarities between osteoporosis in women and men. The higher incidence of fracture in women than in men results from quantitative differences in risk factors rather than from different risk factors. Even though there are sex differences in bone geometry, incidence of fracture seems to be similar in men and women for a same absolute areal bone mineral density. However, the lack of data on the changes in fracture rates in men resulting from pharmacological intervention, leading to changes in bone mineral density or bone turnover, remains the main limitation for extrapolation of established treatment outcomes from women to men.

Age Factors↗
PubMed1996

Breastfeeding pattern in a population with different levels of poverty in Southern Brazil.

A cross-sectional study was conducted on 477 poor children aged 12-59 months in order to investigate their breastfeeding pattern, taking into account the poverty level of their families. Although the population living in extreme poverty had the same pattern of breastfeeding as the rest of the poor population, the former group should still have priority in breastfeeding promotion programs, since they are the population who benefit most with breastfeeding.

Brazil↗
PubMed1991

[Documentation and assessment of adverse drug effects with ofloxacin as an example].

A systematical and comprehensive evaluation of all reports on adverse drug reactions ascribed to ofloxacin since this antibiotic was launched (1985) until October 1988 shows that rare and severe adverse drug reactions are more often reported spontaneously than in the course of clinical trials. In particular, severe reductions of white blood cell counts, shock and shock fragments, and impairment of sensory organs and renal functions have for the first time been detected by spontaneous case reports. The results demonstrate exemplarily the potency of the spontaneous reporting system as superior to that of clinical trials in providing information on rare adverse drug reactions.

Clinical Trials as Topic↗
PubMed1984

[Trial for digitalis withdrawal in hemodialysis patients].

The indication for digitalis treatment was investigated in a controlled and prospective study lasting 12 months in 110 patients on long-term haemodialysis. In ten patients, digitalis was needed because of tachyarrhythmia due to atrial fibrillation and in five because of recurrent pulmonary edema. In 57 patients receiving digitoxin, therapy was discontinued for 4 to 6 weeks, whereas 13 patients not yet treated with digitalis, received digitoxin for 4 weeks. Without digitoxin, trial fibrillation occurred in 4 patients, while no patient experienced atrial fibrillation with digitoxin (P = 0.002). In 13 patients, radiological findings (heart enlargement, pulmonary congestion) were better with digitoxin than without. Thus digitoxin appeared to be clearly indicated in 29% of the haemodialysed patients. Additionally, digitalis was indicated in 31 patients because of heart enlargement, pulmonary congestion and (or) previous pulmonary edema. Initially, 76% of the patients were receiving digitoxin, whereas, after the investigation, the rate was only 57% (P less than 0.001). The prospective frequency of clinically apparent digitoxin intoxication was low (3%) and so were the overall toxic plasma digitoxin levels (5%). Digitalis should be given deliberately but not restrictively to haemodialysis patients, since atrial fibrillation (13%) and heart failure (50%) are frequent and often concealed.

Adult↗
PubMed1984

Effect of repeated plasma exchange on steady state kinetics of digoxin and digitoxin.

The effect of repeated plasma exchanges on the steady state kinetics of digoxin (3 patients) and digitoxin (4 patients) was investigated in 7 patients. Plasma exchange was performed 3 times a week for 4 weeks up to 12 exchanges using a hollow fiber membrane. In each exchange, 4000 ml plasma were filtered within 1 to 2 h and replaced by an albumin containing (20 g/l) physiological electrolyte solution. Digoxin and digitoxin concentrations in blood and filtered plasma were measured by radioimmunoassay. The effects due to the amount eliminated by plasma exchange were distinguished from the effects due to hypoalbuminemia. The eliminative effect was confined to the plasma compartment. It resulted in a marginal decrease in the elimination half-life from 1.6 to 1.59 days for digoxin and 4.3 to 4.2 days for digitoxin. Theoretically, it can be calculated that the hypoalbuminemia caused an increase in the volume of distribution from 451 to 497 l (digoxin) and 35 to 50 l (digitoxin) and a further decrease in the elimination half-life from 4.2 to 4.1 days in the case of digitoxin (not digoxin). If given within 2 h prior to plasma exchange, 13 to 50% of the digitoxin dose (not digoxin) was eliminated. Alteration of digoxin and digitoxin dosage during repeated plasma exchanges is not recommended, but drugs should be given after, not before plasma exchange.

Adult↗
PubMed1982

Quantitative thin-layer chromatographic determination of dihydroergot alkaloids.

Direct, quantitative, thin-layer chromatographic methods for the determination of dihydroergot alkaloids are described, in particular the determination of dihydroergotamine with dihydroergokryptine as internal standard. The internal standard was added to plasma, which was extracted twice in dichloromethane; the organic phase was removed under nitrogen, the residue resolved in ethanol and applied on a silica gel G-60 plate. Dihydroergotamine and the internal standard can be measured directly by fluorescence, with excitation at 264 nm and with use of a Zeiss remission filter FL 39. The percentage recovery from this method is 49.17 +/- 6.71% (plasma). These methods enable the determination of 10 pmol dihydroergotamine per ml of plasma (ca. 6.8 ng/ml) with a coefficient of variation of 10.3%. They have proved useful in biochemical and pharmaceutical applications.

Chromatography, Thin Layer↗
PubMed1982

Ultrastructural studies of the contorted and contralateral testicle in unilateral testicular torsion.

In 7 patients with acute unilateral testicular torsion, bilateral orchiopexy was performed and biopsies were made at the same time for the purpose of light microscopic (semi-thin section method) and electron microscopic examination. All tissue specimens from the twisted and non-twisted gonads showed changes in the form of tubular atrophy, atrophy of the Leydig cells and malformation at the spermatid level. The results indicate primary tissue damage of the testicles, which was already present before torsion occurred. Nevertheless, it is not possible, on the basis of the these findings, to determine definitely whether the disorders of spermiogenesis frequently found in unilateral testicular torsion are the result of possible congenital dysplasia or damage to the germinal epithelium caused by recurrent subtorsion.

Humans↗
PubMed1981

Digoxin-quinidine interaction in patients with renal failure.

Investigations were performed in order to study whether or not quinidine would exert similar effects on the serum digoxin concentration in patients with renal failure as in normal subjects. Fourteen out of fifteen patients showed a significant increase of the serum digoxin level after four days of quinidine application. This indicates, that the quinidine effect is not solely caused by a decrease of the renal digoxin clearance, although nine patients, not being hemodialysed, revealed a correlation between their creatinine clearance and the rise of the serum digoxin concentration after quinidine. As however, the patients on hemodialysis did not show higher digoxin levels than those treated conservatively, it is suggested that the degree of the uremic intoxication might be responsible for the observed correlation.

Acetyldigoxins↗
PubMed1980

[Quantitative DNCB reaction in patients with hypernephroma].

From the examinations may be concluded that the cellular immune response to the unspecific DNCB skin test correlates quite well with the survival time. With the quantification of the test reaction in after-testings comparisons may be rendered, so that by this means already pretty early conclusion may be made on the further course of the disease. For a definitive judgment, however, the numbers of cases got up to now are still too small.

Adenocarcinoma↗
PubMed1979

[Incidence of adrenal metastasis from renal carcinoma].

We analysed the cases of renal carcinoma undergoing operation or autopsy from 1970 to 1978 in respect of their metastasizing to the adrenals. Of the 31 cases undergoing autopsy 10 adrenal metastases were found mostly as a result of a widespread metastasis. Of the operated 74 patients 37 underwent nephrectomy alone and 37 nephrectomy together with prophylactic adrenalectomy. The histologic evaluation of the 37 removed adrenals revealed metastases only in 4 cases. Only one of them proved to be a single metastasis, the other occurring together with other metastatic lesions. The value of the adrenalectomy will be discussed.

Adrenal Gland Neoplasms↗