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Biomedical subjects

U Gerhardt

Publications and source records attributed to U Gerhardt.

At least 37 records · Page 2Linked to original sources
PubMed2000

Inorganic anions and the renal organic cation transport system.

During renal secretion, organic cations (OC) have to pass two hydrophobic membranes (basolateral and luminal) and the intervening aqueous cytoplasm. Furthermore, an uptake in intracellular endosomes may also occur. OC transport critically depends on the presence or absence of certain inorganic anions, such as Cl-, HCO3-, and others. The interaction between inorganic anions and OC may occur during the transport across the membranes or uptake by endosomes, by alterations of the transport protein or the substrate and by changes of the intracellular pH.

Animals↗
PubMed2000

Impact of estradiol blood concentrations on skin capillary Laser Doppler flow in premenopausal women.

OBJECTIVE AND METHOD: Estradiols are known to prevent cardiovascular diseases, but the underlying mechanisms remain unclear. We assessed the finger skin capillary blood flow in 20 premenopausal women with oral contraception noninvasively by Laser Doppler flowmetry (LDF). Blood flow was registered both under basal conditions and after 2 min of arterial occlusion. Furthermore, the combination with a beat-to-beat online finger blood pressure monitor allowed the calculation of the regional peripheral resistance (RPR). All measurements were performed in the menstrual phase. LDF and RPR were correlated to the estradiol whole blood levels. RESULTS: Both baseline (r(2)=0.826; P<0.01) and vasodilation (r(2)=0.747; P<0.01) blood flux were significantly correlated to the corresponding estradiol concentrations. A multiple stepwise regression analysis (with age, height, weight, duration of oral contraception, nicotine pack years and estradiol levels in the equation) showed positive correlations between estradiol levels and (a) baseline (P<0.05) or (b) vasodilation (P<0.05) Laser Doppler flux or (c) time to reach the peak flux (r(2)=0.31; P<0.05). Furthermore, the minimal local vascular resistance was negatively correlated to the estradiol levels (r(2)=0.45; P<0.05). CONCLUSION: The study provides evidence that both the baseline and the vasodilation capillary blood flux in women in the menstrual phase depend on the estradiol whole blood levels. Furthermore, the local vascular resistance shows a negative correlation to the hormonal state. Functional or structural alterations of the microvasculature may therefore contribute to the estradiol-associated cardiovascular protection.

Adult↗
PubMed2000

Effect of homocysteine on carotid intima-media thickness after renal transplantation.

The common carotid intima-media thickness (CC IMT) is a strong predictor for cardiovascular disease in patients with end-stage renal failure. However, little is known about possible associations between potential cardiovascular risk factors such as serum total homocysteine concentrations (tHcy) and the CC IMT. Thus, we investigated (a) the course of tHcy levels after renal transplantation (RTX) and (b) the relationship between CC IMT and tHcy in 53 renal allograft recipients with chronic renal failure before transplantation and 3, 6, and 12 months after transplantation. Exclusion criteria were volume overload, symptomatic coronary artery disease, symptomatic cerebrovascular disease, peripheral artery disease, heart failure, valvular heart disease, diabetes mellitus, severe hypercholesterolemia, and blood pressure above 159/89 mmHg at the time of the investigation. In all renal allograft recipients, a carotid high-resolution B-mode ultrasound measurement of the CC IMT was performed. Eighteen patients had normal ( < 20 micromol/L) pre-transplant (U0) tHcy, 25 had moderately elevated (20-40 micromol/L) pre-transplant (U0) tHcy, and 10 had severely elevated (> 40 micromol/L) pre-transplant (U0) tHcy. After 12 months of follow-up time (U12), no statistically significant differences concerning the tHcy levels could be detected between the groups (average serum tHcy 16.4 micromol/L +/- 1.1 micromol/L). The CC IMT did not differ significantly between the three tHcy groups at any time within the present follow-up. This was also true for the 'wall-to-lumen ratio'. A multiple forward stepwise regression analysis showed that the reduction of the CC IMT was positively correlated with gender (p < 0.01), glucose levels at U12 (p < 0.05; r2 = 0.96), systolic arterial blood pressure at U12 (p < 0.05; r2 = 0.97), and with the intact parathyroid hormone levels at U0 (p < 0.01; r2 = 0.98). In conclusion, (a) tHcy decreases significantly after RTX, but (b) does not influence the CC IMT thickness independently.

Adult↗
PubMed1999

Kidney transplantation improves baroreceptor sensitivity.

Kidney transplant recipients as well as patients on hemodialysis frequently share an increased risk of cardiovascular diseases. Besides other factors, modulations in central neural blood pressure regulation have to be considered as a pathogenetic factor. In this study, baroreceptor function as a possible modulator of blood pressure and the activity of the generating components of the sympathetic nervous system were estimated in 20 kidney transplant recipients, 20 normotensive patients on hemodialysis and 20 age-matched volunteers using the sequence analysis technique and Fast Fourier Transformation (FFT). No blood pressure differences could be measured (83.7+/-2.5 vs. 82.5+/-3.8 vs. 79.2+/-2.4 mm Hg). Pulse interval-blood pressure sequences and the slope of delta pulse interval/delta mean arterial blood pressure of these sequences, representing baroreceptor sensitivity, did not differ between kidney transplant recipients and controls (11.2+/-1.4 vs. 13.4+/-1.3 ms/mm Hg), whereas in hemodialysis patients a reduced baroreceptor sensitivity (5.2+/-1.2 ms/mm Hg) was detected. The 66-129 mHz component (Mayer waves) of heart rate and blood pressure spectrum in normals (650+/-57 and 630+/-70 modulus) significantly (p<0.05) exceeded its equivalent in kidney transplant recipients (430+/-32 and 452+/-27 modulus) and patients on hemodialysis (375+/-38 and 394+/-40 modulus). In conclusion, our study provided evidence that both in kidney transplant and dialysis patients a decreased activity of the generating compounds of the sympathetic nervous system can be detected as compared to healthy volunteers. In contrast to hemodialysis patients, the baroreceptor sensitivity is unaffected in kidney transplant recipients and may, therefore, not contribute to the development of cardiovascular diseases.

Adult↗
PubMed1999

Cyclosporine A modulates baroreceptor function in kidney transplant recipients.

Cyclosporine has been described to increase the sympathetic tone. Alterations in sympathetic tone may contribute to baroreceptor dysfunction. Therefore, in this study baroreceptor function in 20 kidney transplant recipients was investigated under both low and high cyclosporine whole blood concentrations using the sequence analysis technique. The sympathetic nerve activity was estimated by calculating the low frequency oscillation of heart rate and blood pressure following Fast Fourier Transformation (FFT). Besides cyclosporine, azathioprine and prednisolone no other drugs were used. The increase in cyclosporine whole blood levels (from 101+/-13.4 ng/ml to 469+/-52 ng/ml) did not change mean arterial blood pressure significantly (83.7+/-2.5 vs. 82.2+/-2.0 mm Hg). Baroreflex sensitivity in +PI/+RR (+pulsinterval/+blood pressure) sequences, however, increased from 11.2+/-0.4 to 13.0+/-0.5 ms/mm Hg, whereas it was reduced in -PI/-RR (-pulsinterval/-blood pressure) sequences (14.4+/-0.3 to 12.5+/-1.1 ms/mm Hg). The increase in cyclosporine whole blood concentrations was associated with an increase in low frequency oscillation of heart rate (430+/-12 to 461+/-13) and blood pressure (452+/-9 to 469+/-12), indicating an enhanced sympathetic tone. Our results provide evidence that cyclosporine A by itself alters baroreceptor function. An imbalance between the sympathetic and parasympathetic nervous system due to an enhanced sympathetic tone may explain the reduction in -PI/-RR and the increase in +PI/+RR sequence baroreflex sensitivity.

Adult↗
PubMed1999

A world from brave to new: Talcott Parsons and the war effort at Harvard University.

This article argues that for Parsons and some of his colleagues at Harvard, the Second World War and the post-war period provided a context in which their work contributed to the transformation from totalitarianism to democracy in Central Europe (especially Germany) and Japan. The various agendas of Parsons' work are shown, supplemented by that of three of his colleagues with whom he collaborated (Gordon W. Allport, Carl J. Friedrich, Clyde Kluckhohn). The immediate effect of this work, for Parsons, however, meant frustration rather than fame, and his eventual reputation, I maintain, came unexpectedly with the third of his three attempts in the immediate post-war period to sum up what he believed were crucial insights that the Second World War had yielded concerning the ways in which sociology could contribute to the analytical understanding of democracy. The significance of this work is that it was both political and scientific. Because of the world situation of the 1940s, when the Holocaust in Germany was the nadir of civilization, Parsons believed that social science could contribute to the cause of making the world safe for future democracy. In the 1940s, this future depended on brave citizens, or such might have been Parsons' worldview. Targets envisaged for the 1950s, then, were community and citizenship in the newly democratic societies such as (West) Germany, the land that defeated Nazism.

Democracy↗
PubMed1999

Influence of hyperglycemia and hyperuricemia on long-term transplant survival in kidney transplant recipients.

Long-term prognosis in kidney transplant recipients depends on multiple factors. The purpose of this study was to quantify the influence of hyperuricemia and hyperglycemia (elements of the so-called 'syndrome X', i.e., a combination of metabolic disorders like hyperuricemia, diabetes mellitus, hyperlipidemia, and hypertension) on organ function in 350 kidney transplant recipients who had received 375 kidney transplants up to 1990 and in whom sex, age of recipient and donor, nephrologic disease, duration of dialysis, human leukocyte antigen (HLA) classification, and duration of transplant ischemia had been well matched. We found the influence of hyperuricemia on graft survival to be statistically significant (p < or = 0.05), while a statistically significant correlation between hyperglycemia and graft survival could not be detected in the present study. The transplant survival rates 2, 4, and 5 yr post-kidney-transplantation were 96.7, 80.7, and 78.7 in normogylcemic patients vs. 96.9, 85, and 82.7% in hyperglycemic ( > 100 mg,dL) kidney transplant recipients (p > 0.05). Transplant survival in hyperuricemic patients (male, > 8 mg dL; female, > 6.2 mg/dL) 2, 4, and 5 yr post-transplantation was significantly reduced (92.2, 70.6, and 68.8% vs. 98.1, 85.6, and 83.3%), as compared to normouricemic recipients. A combined presence of both hyperuricemia and hyperglycemia probably influencing the prognosis post-kidney-transplantation failed to reach the level of statistical significance. We found a significant correlation between age of recipients and plasma glucose (p < or = 0.01) and between serum uric acid concentrations and diuretic therapy (p < or = 0.05) and gender (p < or = 0.(5). In conclusion, hyperuricemia after kidney transplantation seems to reduce graft survival, whereas an influence of the carbohydrate metabolism has to be denied.

Adult↗
PubMed1999

Blood pressure control in kidney transplant recipients: influence of immunosuppression.

1. Disturbances of the blood pressure regulation, probably due to dysfunction of the autonomic nervous system, are well known complications in chronic renal failure. Haemodialysis and transplantation have been reported to ameliorate nerve dysfunction. 2. In this study, the function of the blood pressure control was investigated in kidney transplant recipients after longtime haemodialysis treated with ciclosporine A and tacrolimus and compared to healthy individuals. To investigate the influence of immunosuppression, the measurements were performed twice, at low and high whole blood concentrations of ciclosporine and tacrolimus. Besides ciclosporine, tacrolimus, azathioprine and prednisolone no other drugs were used in the group of kidney transplant recipients. 3. Kidney transplant recipients (KTR) treated with ciclosporine showed reduced blood pressure and heart rate responses to the cardiovascular stress tests (head-up tilt and cold pressure test) under basal conditions. Two hours after ciclosporine application, the differences in the responses to cardiovascular stress tests between KTR and controls were significantly more pronounced. 4. Patients with tacrolimus immunosuppression showed a similar blood pressure and heart rate response under basal conditions. Two hours after drug application, the blood pressure response following orthostatism and heart rate response to the cold pressure test were significantly higher in tacrolimus treated patients. 5. Our results indicate, that kidney transplant recipients still express an altered function of the blood pressure control. Furthermore, ciclosporine A and tacrolimus seem to contribute to dysfunction of the blood pressure regulation by their own. Tacrolimus immunosuppression does not seem to offer advantages concerning the function of the blood pressure control as compared to ciclosporine A.

Adult↗
PubMed1999

Acute and persistant effects of smoking on the baroreceptor function.

Recent studies showed that to smoke four cigarettes within one hour impairs baroreflex sensitivity in humans. In the present study, these effects were qualified more precisely from blood pressure and heart rate records by a sequence analysis and by Fourier analysis of Finapres-registrations. The Mayer waves of the heart rate PDS (power density spectrum), partially representing sympathetic activity, increased during smoking (83.7 +/- 1.0 AU to 89.5 +/- 1.1 AU, P < or = 0.05) and decreased after smoking (86 +/- 1.0 AU, P < or = 0.05). They did, however, not reach baseline levels again within 30 min. Probably due to this, mean arterial blood pressure (64.3 +/- 1.3 mmHg vs. 76.9 +/- 1.3 mmHg, P < 0.05) and heart rate (71.8 +/- 1.4 min(-1) vs. 82.9 +/- 1.4 min(-1), P < 0.05) increased unequivocally after smoking. On the other hand, baroreflex sensitivity decreased dramatically from 15.4 +/- 1 to 11.2 +/- 0.6 ms mmHg(-1) (P < 0.05). This finding was associated with an increased heart rate variability after smoking (6 +/- 0.5 min(-1) vs. 9.2 +/- 1 min(-1)) Thus, the present study provides evidence that chronic tobacco (nicotine)-abuse causes pathologic alterations of the baroreflex control. In synergism with other processes like elevated catecholamine blood levels, these alterations may contribute to the higher risk of cardiovascular diseases.

Blood Pressure↗
PubMed1999

Influence of smoking on baroreceptor function: 24 h measurements.

OBJECTIVE: Recent studies showed that smoking four cigarettes per hour impairs baroreflex sensitivity in humans. In this study, baroreceptor function was qualified more precisely by 24 h measurements using the new portable Portapres system, allowing a continuous non-invasive registration of blood pressure curves. METHODS: Twenty-four smoking individuals (12 male/12 female) who smoked more than 10 cigarettes per day for more than 6 years were investigated. Thirty non-smokers (15 male/15 female) served as controls. Data were evaluated separately for the 08:00-22:00 h and 22:00-08:00 h periods. RESULTS: Within one 24 h period, smokers showed a higher blood pressure [female: mean arterial blood pressure (MAP) 85.5 mmHg; male: MAP 93 mmHg] compared to non-smokers (female: MAP 80 mmHg; male: MAP 90 mmHg). During daytime (08:00-22:00 h), this difference reached a level of statistical significance (P< 0.05) in female subjects. Heart rate was significantly higher in smokers (female: 86 bpm; male: 80 bpm) compared to non-smokers (female: 77 bpm; male: 70 bpm) during the 24 h observation period. The number of sequences (seq) in smokers surpassed the number of sequences in non-smokers by about 53 seq/day, which corresponds to a significant difference of 4.5%. At night the sympathetic -systolic blood pressure/-pulse interval (-SBP/-PI) sequences of the smoking group predominated over the -SBP/-PI sequences in the non-smoking group. On the other hand, the parasympathetic +SBP/+PI sequences were significantly less in smokers between 22:00 and 08:00 h. The regressions (i.e. D pulse interval/D SBP [ms/mmHg]), which represent the baroreceptor sensitivity, were clearly smaller in smokers. CONCLUSIONS: The present study provides evidence that chronic tobacco (nicotine) abuse causes pathological alterations of autonomic nervous blood pressure regulation which can be measured under normal living conditions and may be described as sympathovagal dysbalance and decreased baroreceptor sensitivity. Taken together with processes such as elevated catecholamine blood levels, these alterations may explain the higher risk of cardiovascular diseases.

Adult↗
PubMed1998

[Hypotension in acyclovir therapy].

A 51 year old man developed Herpes zoster on the right arm (C5/C6) treated subsequently with aciclovir infusions (500 mg, 3/day). Ten months before hospital admission he did have a radical resection of a epi-oro-hypopharyngeal carcinoma (T4/N1/G2, M0; lymphangiosis carcinomatosa) as well as a partial laryngeal resection for a recurrence 3 months later and removal of a cervical lymph node metastasis after two further months. During aciclovir treatment the patient experienced repeated bradycardia with hypotension verifiable with the tilt-table test. The bradycardias could not be further characterized by ECC. Neither sonography nor CT-scans gave an indication for infiltration of the cervical course of the vagus or glossopharyngeal nerves. Serum catecholamines were, however, markedly reduced. After cessation of aciclovir the bradycardias and hypotensive episodes disappeared. A final tilt-table test was unremarkable. A reversible autonomic neuropathy induced by aciclovir seems a possible explanation.

Acyclovir↗
PubMed1995

[Long-term follow-up of tooth transplantation from the functional and periodontal viewpoint].

The outcome of 81 of 99 patients being treated from 1980 to 1993 by transplantation of autologous teeth was investigated. The overall transplant survival rate was 91% after 1 year, 81% after 5 years and 70% after 9 years. The early loss of transplanted teeth was due to healing disorders. The long-term losses were due to caries and replacement resorption. Caries in tooth transplants has to be treated very early, because deep caries or deep drilling leads to an infection of the nutrient canals of the osteodentine. If the pulp chamber of a transplant is once obliterated by osteodentine, endodontic treatment can no longer be performed in many cases. The periodontal condition of the transplants did not differ from that of normal teeth. In 23% there was a decreased tooth mobility, caused by ankylosis of the transplant. 51% of the transplants showed occlusal disturbances but none of the patients had signs of occlusal traumatization of the teeth or of the temporomandibular joint. In comparison to success rates taken from the literature it is pointed out that tooth transplantation has a better long-term prognosis than endodontic treatment. Therefore, in young patients requiring root canal treatment, tooth transplantations should be considered.

Adolescent↗
PubMed1993

[Social status position and social development following coronary bypass surgery].

For the individual the status passage from employment to retirement means a process of social aging. Retirement can involve old-age pensions or disability pensions. Regarding the quality of medical rehabilitation, four forms of social aging emerge: normal, accelerated, adequate and delayed aging. Empirical courses of rehabilitation are explored in a qualitative study on patients after Coronary Bypass Surgery. These courses comprise in each case a specific form of social aging as individual process. The hypothesis is verified whether different forms of aging are typical for different SES. Furthermore the question is ventured whether early retirement is a status-bound destiny or an individual strategy.

Adult↗