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Biomedical subjects

W Ernst

Publications and source records attributed to W Ernst.

At least 55 records · Page 3Linked to original sources
PubMed1983

An automated statis perimeter/adaptometer using light emitting diodes.

An automated static perimeter/adaptometer is described which measures thresholds with lights of 2 wavelengths. The instrument uses light-emitting diodes to produce the stimuli and is controlled by a small computer, making it very suitable for clinical testing of large numbers of patients. The use of 2 LEDs with different peak emission wavelengths (530 and 660 nm) permits an assessment of the relative state of rod and cone mechanisms in a particular region of the retina either during dark adaptation or when the eye is fully dark adapted.

Dark Adaptation↗
PubMed1983

Acute vascular rejection treated by plasma exchange.

Since 1980 we have treated in 14 patients 19 steroid resistant acute vascular rejection (AVR) episodes by plasma filtration (PF). Each episode was treated by six PF with 5L plasma being filtered and simultaneously replaced by 3.5 per cent Albumin-Ringer-lactate. After each PF 20g immunoglobulin (Intraglobin) was given intravenously. In all cases renal function improved following PF. In the long term one graft was lost due to chronic irreversible vascular rejection, all others are still functioning, nine of them six months and eight of them 12 months post PF treatment. They show no signs of rejection. PF with repletion of immunoglobulins after treatment is a simple and safe procedure, which in our hands proved to be quite effective in reversal of AVR.

Biopsy↗
PubMed1983

Reversal of acute vascular rejection by plasma exchange.

The vast majority of grafts with acute vascular rejection (AVR) undergo irreversible loss of function, since this type of rejection usually does not respond to increased levels of immunosuppression. Since 1980 we have treated with plasmafiltration (PF) 14 steroid resistant episodes of AVR in 10 patients. In the treatment of each episode 6 X 5 L plasma were filtered and simultaneously replaced with 3.5% albumin-Ringer-lactate solution. After each PF, 20 g immunoglobulins (Intraglobin) were replaced i.v. In all cases following PF renal function improved. One graft was eventually lost as a result of chronic irreversible vascular rejection; all others are still functioning. Eight of the 10 patients have been observed now for at least 6 months since beginning PF treatment and 5 of these 8 have been followed for more than 12 months. None of them shows signs of rejection. PF with replacement of immunoglobulins after treatment appears to be a simple and safe procedure, which in our hands proved to be quite effective in reversing AVR.

Arteries↗
PubMed1983

Improved graft prognosis by treatment of steroid resistant rejections with ATG and plasmapheresis.

Conventional therapy of acute rejection is almost exclusively based on increased steroid dosage, however, a considerable number of grafts undergo irreversible steroid resistant rejection (SRR). We investigated in a prospective study the effects of antithymocyte globulin (ATG) and plasmafiltration (PF) in cases of SRR. Acute interstitial rejections were treated with ATG, acute vascular rejections with PF. Thirty-nine of 42 (93%) cases of SRR were reversed by these forms of therapy. In 68 recipients of first cadaveric renal allografts actuarial one year graft survival has improved to 88 (+/- 5) per cent since the introduction of ATG and PF for SRR. Severe side effects or increased mortality were not observed, none of the patients with either form of therapy died. Thus ATG and PF are valuable adjuncts in the treatment of SRR.

Antilymphocyte Serum↗
PubMed1983

Acute vascular rejection treated by plasma exchange.

The vast majority of grafts with acute vascular rejection (AVR) undergoes irreversible loss of function, since this type of rejection usually does not respond to increased immunosuppression. Since 1980 we have treated in 22 patients 27 steroid resistant AVR by plasmafiltration (PF). Per episode 6 x 5 L plasma were filtered and simultaneously replaced by 3.5% Albumin-Ringer-lactate. After each PF 20 g immunoglobulins (Intraglobin(R] was substituted i.v.. In all cases renal function improved following PF. In the long run 1 graft was lost due to chronic irreversible vascular rejection, in 2 patients rejection was not reversed by PF, all others are still functioning, 19 of them 6 months and 8 of them 12 months post PF treatment. They show no signs of rejection. PF with repletion of immunoglobulins after treatment is a simple and safe procedure, which in our hands proved to be quite effectful in reversal of AVR.

Acute Disease↗
PubMed1983

Hemodynamics in hemofiltration.

To study the established but not well understood phenomenon of improved intratreatment vascular stability during hemofiltration the same 10 stable hemodialysis patients were investigated during one hemodialysis and one hemofiltration treatment. Both treatments were matched in regard to linear fluid withdrawal (3 kg/240 minutes), small molecule removal rate (Curea 120 ml/min). Sodium (140 meq/l) and acetate (35 meq/l) concentration in dialysate and replacement fluid were identical. Outcome measures included mean arterial blood pressure, total peripheral vascular resistance by thermodilution, plasma noradrenaline concentration as index of sympathetic activity and sodium loss per treatment. Blood pressure was maintained during hemofiltration, while total peripheral vascular resistance and plasma noradrenaline concentrations increased. During hemodialysis mean arterial blood pressure fell significantly, total peripheral resistance and plasma noradrenaline concentrations remained unchanged. During both treatment modalities sodium loss was comparable. It is concluded, that the improved hemodynamic stability during hemofiltration is due to a maintained physiologic response to ultrafiltration, which is impaired during hemodialysis. Vascular stability during hemofiltration is not due to sodium retention relative to hemodialysis.

Adult↗
PubMed1982

Sympathetic and hemodynamic response to volume removal during different forms of renal replacement therapy.

Sympathetic and hemodynamic response to a constant volume removal was investigated during pure ultrafiltration, hemofiltration, acetate hemodialysis, and bicarbonate hemodialysis in the same ESRD patients. Small solute removal rates were matched. The sympathetic response resulting in an increase of total peripheral vascular resistance was found to be qualitatively adequate in ultrafiltration and hemofiltration, but not in acetate and bicarbonate hemodialysis. This inadequate response to volume removal explains the clinically observed hemodynamic instability during hemodialysis. The purpose of the study was to substantiate the, compared to hemodialysis, improved tolerance to fluid withdrawal during ultrafiltration and hemofiltration with hemodynamic data and to correlate hemodynamic and sympathetic changes during the different treatment modalities of uremia.

Adult↗
PubMed1981

Flash photolysis of rhodopsin in the cat retina.

The bleaching of rhodopsin by short-duration flashes of a xenon discharge lamp was studied in vivo in the cat retina with the aid of a rapid, spectral-scan fundus reflectometer. Difference spectra recorded over a broad range of intensities showed that the bleaching efficacy of high-intensity flashes was less than that of longer duration, steady lights delivering the same amount of energy. Both the empirical results and those derived from a theoretical analysis of flash photolysis indicate that, under the conditions of these experiments, the upper limit of the flash bleaching of rhodopsin in cat is approximately 90%. Although the fact that a full bleach could not be attained is attributable to photoreversal, i.e., the photic regeneration of rhodopsin from its light-sensitive intermediates, the 90% limit is considerably higher than the 50% (or lower) value obtained under other experimental circumstances. Thus, it appears that the duration (approximately 1 ms) and spectral composition of the flash, coupled with the kinetic parameters of the thermal and photic reactions in the cat retina, reduce the light-induced regeneration of rhodopsin to approximately 10%.

Animals↗
PubMed1981

X-linked retinitis pigmentosa: reduced rod flicker sensitivity in heterozygous females.

A flicker sensitivity test based on measuring modulation thresholds for light varying sinusoidally with time around two mean scotopic luminances was performed on 21 female patients heterozygous for X-linked retinitis pigmentosa and 22 normal observers. The patients required, on average, 1.5 times the normal modulation to detect flicker over the whole frequency range where thresholds could be measured. The results suggest that the rod system of heterozygotes exhibits a reduced signal-to-noise ratio compared with normal but that the dominant time delays in the signaling process are not significantly altered.

Female↗
PubMed1980

[Autonomic circulatory regulation in uremia (author's transl)].

Uremic autonomic neuropathy leads to impaired function of the baroreflex. The main defect, according to literature, is located in the afferent limb of the reflex arc and in the efferent cardiac vagus nerve, whereas the sympathetic part of the efferent arc is still intact. Own results, obtained in hemodialysis patients during orthostasis and volume removal induced sympathetic stimulation, showed qualitatively and quantitatively adequate sympathetic response and also an adequate end organ receptor response. Autonomic nervous neuropathy predisposes to volume removal related symptomatic hypotension during hemodialysis treatment. In addition hemodialysis treatment per se induces a so far unexplained interference with sympathetic response to volume removal. The autonomic neuropathy also predisposes to development of hypertension in response to volume load.

Autonomic Nervous System↗
PubMed1980

Differing haemodynamic stability due to differing sympathetic response: comparison of ultrafiltration, haemodialysis and haemofiltration.

In 12 RDT patients the volume removal related haemodynamic changes were correlated with concomitant changes in sympathetic activity during pure ultrafiltration (UF), post dilution haemofiltration (HF) and haemodialysis using either acetate (HDA) or bicarbonate (HDB) as buffer substitute. Total peripheral resistance (TPR) and plasma noradrenaline concentrations (PNA) increased during UF indicating a qualitatively adequate reaction of ESRD patients to volume removal. This physiological response is maintained during HF, resulting in intratreatment haemodynamic stability. In contrast no increase of PNA and insignificant changes of TPR were seen in HDA and HDB. As small molecule clearances were matched to those in HF, the behaviour of PNA indicates that not PNA removal but an impaired sympathetic response during HDA and HDB is responsible for the inadequate rise of TPR.

Adult↗