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Biomedical subjects

K Schaefer

Publications and source records attributed to K Schaefer.

At least 37 records · Page 2Linked to original sources
PubMed1995

Is the choice of membrane important for patients with acute renal failure requiring hemodialysis?

It has recently been reported that patients with acute renal failure requiring hemodialysis have an improved recovery of renal function and a higher survival rate when the dialysis treatments are performed with a biocompatible membrane rather than a bioincompatible membrane. Our data, obtained in 57 patients with acute renal failure, do not support these findings since neither the mortality nor the required number of dialysis sessions could be influenced by using a biocompatible membrane. The survival rate was similar in both groups (64 versus 72%), and renal function was regained in both groups after 6 dialysis sessions. We conclude that when reviewing the literature as well as other factors, the underlying clinical condition or the skill of the physicians is probably more important than the theoretical superiority of biocompatible membranes.

APACHE↗
PubMed1994

Evaluation of the new ophthalmic antihistamine, 0.05% levocabastine, in the clinical allergen challenge model of allergic conjunctivitis.

The objective of this study was to evaluate the efficacy of 0.05% levocabastine, a new antihistamine formulated for ophthalmic use, compared with the placebo vehicle for the treatment of allergic conjunctivitis induced by ocular allergen challenge. Subjects who reacted. positively in both eyes on two separate occasions to ocular allergen challenge with grass, ragweed, or cat dander (N = 47) received one dose of 1 to 2 drops of 0.05% levocabastine in one eye and its vehicle in the other eye. After 10 minutes, the predetermined dose of allergen was instilled in both eyes. Signs and symptoms of allergic conjunctivitis were evaluated with biomicroscopy and subjective evaluation of itching after 3, 5, and 10 minutes. Four hours after drug administration, subjects were rechallenged and reevaluated to determine levocabastine's duration of action. Results showed that levocabastine was significantly more effective than placebo in inhibiting itching, hyperemia, eyelid swelling, chemosis, and tearing after the initial challenge and in inhibiting all parameters except eyelid swelling after the rechallenge 4 hours later (p < 0.05). These results demonstrate that levocabastine, currently the only ophthalmic antihistamine available that is not combined with a vasoconstrictor, is efficacious in the inhibition of itching, as well as all of the allergic signs of a vascular origin, with a duration of action of at least 4 hours. Because of its strong effects on itching and hyperemia, chemosis, lid swelling, and tearing, levocabastine would be a valuable therapeutic agent to add to the heterogeneous family of antiallergic compounds presently available for the treatment of seasonal allergic conjunctivitis.

Adolescent↗
PubMed1992

Reduced risk of hypercalcemia for hemodialysis patients by administering calcitriol at night.

Renal osteodystrophy therapy in dialysis patients with calcitriol and intestinal phosphate binders containing calcium entails the risk of hypercalcemia. A study was performed using 35 hemodialysis patients to see whether the time of day when calcitriol is administered influences the incidence of hypercalcemia. It was shown that simply by administering at night (11:00 PM), the occurrence of hypercalcemia was significantly reduced. While greater than 80% of patients developed hypercalcemia when calcitriol was administered in the morning, when administered at night, this figure was only 50% (P less than 0.013). At the same time, the extent of hypercalcemia when calcitriol was administered at night was significantly lower than when it was administered in the morning. The incidence of hypercalcemia occurred regardless of the type of phosphate binder containing calcium used, whether it was calcium acetate or calcium carbonate. In addition, hypercalcemic episodes were always associated with hyperphosphatemia. On the basis of the above information, it would be expedient to administer calcitriol at night to dialysis patients, in order to reduce the risk of hypercalcemia and to preserve the hypophosphatemic effect of the applied intestinal phosphate binders.

Acetates↗
PubMed1992

Beta-2-microglobulin-derived amyloidosis: onset, distribution and clinical features in 13 hemodialysed patients.

Postmortem examinations were carried out in 13 patients (6 males, 7 females, age 58 +/- 9 years) who had been on regular hemodialysis treatment for 10-90 months using disposable regenerated cellulose membrane dialyzers. The prevalence of beta 2-microglobulin (beta 2m)-derived AB-amyloid deposits in different sites was determined. At autopsy, specimens were obtained from different joints, paravertebral tissue, intervertebral discs and from visceral organs. During life, routine laboratory parameters and radiographic studies had been carried out at 6-month intervals. Serum levels of beta 2m were elevated in all patients (57.5 +/- 13.4 mg/l). Synovial AB-amyloid deposits were shown in different joints of 4 patients, aged between 59 and 73 years, and dialysed for 10-90 months, respectively. All had been unremarkable by X-ray and asymptomatic. No amyloid could be detected in the intervertebral discs of 2 further patients suffering from destructive spondylarthropathy. In 11 of the 13 patients, extracellular beta 2m deposits were observed by immunohistochemistry in different tissues. The results document that (a) AB-amyloidosis may occur in elderly patients even when dialysed for less than 5 years; (b) most cases are completely asymptomatic; the appearance of symptoms must be dependent on additional factors, e.g., site of AB-amyloid deposition and intensity of inflammatory reaction, and (c) AB-amyloid is not the exclusive cause of destructive spondylarthropathy, as 2 typical cases were observed who were devoid of amyloid.

Amyloidosis↗
PubMed1991

Sequence and functional expression in Xenopus oocytes of a human insulinoma and islet potassium channel.

Regulation of insulin secretion involves the coordinated control of ion channels in the beta-cell membrane. We have isolated and characterized cDNA and genomic clones encoding a voltage-dependent K+ channel isoform expressed in human islets and in a human insulinoma. This K+ channel isoform, designated hPCN1, with a deduced amino acid sequence of 613 residues (Mr = 67,097), is related to the Shaker family of Drosophila K+ channels. hPCN1 is homologous to two other human K+ channel isoforms we have isolated, hPCN2 and hPCN3, with 55% and 65% amino acid sequence identity, respectively. The electrophysiological characteristics of hPCN1 were determined after microinjection of synthetic RNA into Xenopus oocytes. Two-microelectrode voltage-clamp recordings of oocytes injected with hPCN1 RNA revealed a voltage-dependent outward K+ current that inactivated slowly with time. Outward currents were inhibited by 4-aminopyridine with a Ki less than 0.10 mM and were relatively insensitive to tetraethylammonium ion or Ba2+. A delayed rectifier K+ channel such as hPCN1 could restore the resting membrane potential of beta cells after depolarization and thereby contribute to the regulation of insulin secretion.

Amino Acid Sequence↗
PubMed1991

The treatment of uraemic hyperphosphataemia with calcium acetate and calcium carbonate: a comparative study.

A comparative study of long-term haemodialysis patients investigated the effects of calcium acetate and calcium carbonate on concentrations of serum phosphate, calcium, and parathyroid hormone. It was demonstrated that both substances led to a significant decrease in phosphate and serum parathyroid hormone. Administration of calcium acetate reduced the serum phosphate concentration in 7 weeks from an initial value of 2.08 +/- 0.53 mmol/l to 1.51 +/- 0.39 mmol/l (P less than 0.01). Following a 1-week wash-out period, calcium carbonate reduced the serum phosphate concentration in the same patients from 1.99 +/- 0.62 mmol/l to 1.34 +/- 0.40 mmol/l (P less than 0.01). Of particular significance, however, is the fact that in relation to daily elementary calcium intake, calcium acetate was a considerably more effective binder of intestinal phosphate than calcium carbonate. During administration of calcium acetate only 1.02 g of elementary calcium were required daily in order to reduce the serum phosphate concentration. The same patients, however, required 1.88 g of elementary calcium during calcium carbonate therapy. Complementary studies investigated the influence of an accompanying calcitriol medication. In this instance, too, calcium acetate was shown to be more effective; although the patients developed hypercalcaemia with calcium acetate, this happened more often with calcium carbonate. In summary it can be said that daily calcium loading of the uraemic organism under calcium acetate therapy is reduced by nearly half as compared to calcium carbonate therapy, and that this can be achieved with the same effective decrease of the serum phosphate concentration.

Acetates↗
PubMed1991

Beta 2-microglobulin serum concentration and associated amyloidosis in dialysis patients.

Using radioimmunological estimation of beta 2-microglobulin (beta 2M), significantly greater serum values were found in 36 dialysis patients (44.4 +/- 20.3 mg/l) in comparison to healthy probands (1.5 +/- 0.2 mg/l). A significant relation to the duration of dialysis, diuresis and serum aluminium and ferritin was found. The used dialysers MLW 1.3/1.8 m2 (regenerated cellulose membrane) did not eliminate beta 2M from the blood. Significantly greater beta 2M concentrations were observed in patients suffering from arthralgia and bone pain, but not in radiologically verified arthropathy and destructive spondylarthropathy. Post-mortem examinations of 13 patients on haemodialysis treatment for between 10 and 90 months revealed synovial beta 2M-derived (AB-)amyloid deposits in four patients at different joints, but not in radiologically suspect areas. The results suggest that independent of serum beta 2M, beta 2M-derived amyloidosis may occur in elderly patients on dialysis for less than 5 years. Several cases were completely asymptomatic.

Adult↗
PubMed1990

[Serum level and organ deposits of beta 2-microglobulin in dialysis patients].

In radioimmunological estimation of beta 2-microglobulin (beta 2m) significant higher serum values were found in 36 dialysis patients (44.4 +/- 20.3 mg/l) in comparison with healthy probands (1.5 +/- 0.2 mg/l). A significant relation to the duration of dialysis, diuresis, symptoms of the musculo-skeletal system, but not to radiologic changes or bone biopsy findings could be seen. Post mortem examinations carried out in 21 dialysis patients revealed AB-amyloid deposits in synovial tissue of different joints (particularly shoulder and hip joint) or intervertebral discs in eight patients (age 48 to 73 years, dialysis duration less than four years) without correlation to serum beta 2m level or radiographically suspect areas. In the tissue of cervical spine or intervertebral discs of two patients suffering from destructive spondylarthropathy no amyloid could be detected. These results suggest that AB-amyloid may occur in elderly patients early in the course of hemodialysis and may be asymptomatic in most cases.

Aged↗
PubMed1990

[Drug utilization in Hvalsö. An attempt to change the attitude of the population and physicians to drug use].

All of the prescriptions, a total of 1,876, issued by the five practitioners in Hvalsø in four chosen weeks in 1987/88 were copied. The prescribed drugs, a total of 3,177, were calculated for the individual groups of drugs and corrected for the age distribution among the population as a whole and in the individual doctor's practice. The main results from the following groups of drugs are presented here: hypnotics, drugs for neurosis, antibiotics, drugs for cardiac and circulatory disease, drugs for asthma, contraceptive pills and female sex hormones. By and large, considerably more medicine was prescribed for women than for men. For example, twice as much medicine for insomnia was prescribed for women. This is enough for every fourth woman over the age for 70 years to receive a daily dose of hypnotics. Women appear to commence using hypnotics at the age of 40 years and men at 60 years. Marked differences were found in the patterns of prescription between the individual practitioners and thei is apparently greatest as regards prescriptions for men while the more liberal prescription of hypnotics to women was observed for all of the practitioners. Two groups of drugs were, however, prescribed mostly for men, viz, asthma medicine for all age groups and cardiac and circulatory medicine for persons greater than 60 years. Where all of the groups of drugs were concerned, comparisons were undertaken between the prescription habits of the individual practitioners. The results of this investigation are employed in local health work among the population, in study circle work among the practitioners and as basic ideas for the county drug committee activities.

Attitude of Health Personnel↗