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Biomedical subjects

J Friedrich

Publications and source records attributed to J Friedrich.

At least 55 records · Page 3Linked to original sources
PubMed1997

Interpretation of multiple Q(0,0) bands in the absorption spectrum of Mg-mesoporphyrin embedded in horseradish peroxidase.

Mg-mesoporphyrin horseradish peroxidase (MgMP-HRP) and MgMP-HRP complexed with naphtohydroxamic acid (NHA) have been studied by fluorescence line narrowing (FLN) and pressure tuning spectral hole burning (SHB) techniques. In each sample, the low temperature absorption spectra show more than one transition in the origin range of the Q band. Comparisons with broad-band fluorescence spectra and FLN studies suggest that the multiple band feature originates from the presence of different configurations of the metal-porphyrin that are subject to Qx-Qy splitting within the protein cavity. This suggestion is supported by pressure tuning SHB studies. In the uncomplexed as well as in the NHA-complexed form of MgMP-HRP, irradiation in the Q band produces photoproduct bands, which has been attributed to a species with smaller Qx-Qy splitting. In an amorphous matrix, on the other hand, only one form of MgMP could be found, and no splitting could be observed. The binding of NHA does not significantly alter the bulk parameters of the protein matrix, but it reduces the structural variety in the configuration of MgMP to a single form with a more distorted structure and thus with an enlarged Qx-Qy splitting.

Horseradish Peroxidase↗
PubMed1997

[Aorto-duodenal fistula--direct suture and pedicled omentum flap-plasty].

Between 1985 and 1993, six patients underwent emergency operation at the Department of General Surgery, Essen University Hospitals, for a secondary aorto-duodenal fistula. In all patients, a Dacron tube- or bifurcation prosthesis has been implanted 1-10 years previously to repair an arteriosclerotic aneurysm of the abdominal aorta. The main symptom of the aorto-duodenal fistula was massive gastrointestinal hemorrhage, with manifest shock in two cases. The most reliable diagnostic procedure, in addition to ultrasonography, was found to be computed angio-tomography. In three cases where there was erosion around the proximal aorto-prosthetic anastomosis, bacterial contamination was found during surgery. Direct reconstruction and pedunculated omentum plasty appear to be a safe method for closing an aorto-duodenal fistula. No patient died in the immediate postoperative period after direct reconstruction. One patient, however, died three months after surgery of myocardial infarction. Two patients suffered from fistula recurrence 1.25 and 3 years respectively after operation and died as a result. One patient died of the sequelae of a chronic obstructive pulmonary disease 3.5 years after the operation. The remaining two patients are still alive and free of complications more than 4 years after operation. Direct reconstruction and pedunculated omentum plasty appear to be a safe method for closing an aorto-duodenal fistula.

Aged↗
PubMed1997

[Unilateral neck exploration in primary hyperparathyroidism].

Within a prospective case control study from 1993 to 1996, in 85 first operations for primary hyperparathyroidism the neck exploration was ended unilaterally when an adenoma (also histologically proven) and one normally small parathyroid gland were found. Otherwise or in case of simultaneous surgery of the thyroid gland, a bilateral exploration was performed. The primary success rate with this strategy, additionally based on 69.4% correct results of cervical ultrasound, was 95.3%, with a significant saving of an average of 30 min. operating time.

Adenoma↗
PubMed1996

Spectral diffusion and the energy landscape of a protein.

We present a novel type of spectral diffusion experiment in the millikelvin range to characterize the energy landscape of a protein as compared with that of a glass. We measure the time evolution of spectral holes for more than 300 hr after well-defined initial nonequilibrium conditions. We show that the model of noninteracting two-level systems can describe spectral diffusion in the glass, but fails for the protein. Our results further demonstrate that randomness in the energy landscape of a protein shows features of organization. There are "deep minimum" states separated by barriers, the heights of which we are able to estimate. The energy landscape of a glass is featureless by comparison.

Diffusion↗
PubMed1996

Creatine kinase system in failing and nonfailing human myocardium.

BACKGROUND: The creatine kinase (CK) reaction is important for rapid resynthesis of ATP when the heart increases its work. Studies defining the CK system in human failing and nonfailing myocardium are limited and in conflict. To resolve this conflict, we measured the activities of CK and its isoenzymes and the contents of creatine and CK-B in homogenates of human myocardium. METHODS AND RESULTS: Myocardium was sampled from 23 subjects who underwent heart transplant, 36 subjects maintained in an intensive care unit before heart harvesting, 13 accident victims, and 2 patients undergoing heart surgery. Since the characteristics of myocardium of potential organ donors differed from those of myocardium of accident victims, data are presented for three groups: failing, donor, and control. CK activity was 7.7 +/- 1.9 and 6.0 +/- 1.4 IU/mg protein in left (LV) and right (RV) ventricles of failing, 9.4 +/- 2.5 and 10.7 +/- 2 IU/mg protein in LV and RV of donor, and 11.6 +/- 2.4 IU/mg protein in LV of control hearts. CK-MM and the mitochondrial isoenzyme activities were lower in failing and donor LV, and CK-MB activity and CK-B content were higher in failing and donor hearts. Creatine contents were 64 +/- 25 and 56 +/- 18.6 nmol/mg protein in LV and RV of failing, 96 +/- 30 and 110 +/- 24 nmol/mg protein in LV and RV of donor, and 131 +/- 28 nmol/mg protein in LV of control hearts. CONCLUSIONS: In failing and nonfailing donor human myocardium, there is a combined decrease of CK activity and creatine that may impair the ability to deliver ATP to energy-consuming systems.

Adolescent↗
PubMed1996

The anastomotic stoma: a useful procedure in emergency bowel surgery.

In emergency surgery of the bowel a primary anastomosis may be risky. Discontinuing colostomies have the disadvantage that a secondary laparotomy is necessary to restore continuity. If sufficient bowel loop mobilization is possible, we prefer to perform an anastomotic stoma. After resection of the diseased bowel segment, we bring the proximal and distal loop together and proceed to the anastomosis of the posterior wall. The anterior wall of the anastomosis remains open and is then fixed to the abdominal wall as a stoma. So far, we have used this method in 91 patients. In 73 cases this technique was performed during emergency operations. No patient died as a result of complications of the method: 21 patients, however, died as a consequence of their primary disease. Bowel continuity could be restored in 78 cases. The anastomotic stoma protects the posterior wall from elevated pressure and allows daily control of the anastomosis. In the case of extraperitoneal closure, a secondary laparotomy for reconstruction of the continuity is not necessary. The anastomotic stoma can be performed in most regions of the small and large bowel.

Adult↗
PubMed1996

Stark effect experiments in cytochrome c-type proteins: structural hierarchies.

We performed hole-burning Stark effect experiments on cytochrome c in which the iron of the herne was either removed or replaced by Zn. According to the experiments, the free-base compound has an effective inversion center, even in the protein. The Zn compound, on the other hand, shows quite peculiar features: in the low-frequency range of the inhomogeneous band, it definitely has a dipole moment, as indicated by a splitting of the hole in the external field. However, in the maximum of the inhomogeneous band, a severe charge redistribution occurs, as the experiments show. In addition to the Stark experiments, we performed calculations of the electrostatic fields at the pyrrole rings and at the metal site of the heme group. We interpret our findings with a model based on structural hierarchies: the protein can exist in a few subconformations, which can be distinguished through the structure of the heme pocket. The different pocket structures support different structures of the chromophore, which, in turn, can be distinguished through their behavior in an external field. These distinct structures, in turn, correspond to a rather broad distribution of protein structures, which leave, however, the pocket structure largely unchanged. These structures show up in inhomogeneous broadening.

Animals↗
PubMed1996

Decreased energy reserve in an animal model of dilated cardiomyopathy. Relationship to contractile performance.

An animal model was used to test the hypothesis that in heart failure the decrease in the ability to resynthesize ATP through the creatine kinase (CK) reaction (which we call energy reserve) contributes to the inability of the heart to maintain its normal function and contractile reserve. One-week-old turkey poults were fed furazolidone for 14 days to induce dilated cardiomyopathy. Isolated Langendorff-perfused hearts from these myopathic animals showed a 73% decrease in baseline isovolumic contractile performance. Neither increasing [Ca2+]o nor electrical pacing rate increased isovolumic contractile performance. Measured by 31P nuclear magnetic resonance magnetization transfer and chemical assay, ATP concentration was decreased by 23%, phosphocreatine concentration by 42%, CK enzyme activity by 34%, and the pseudo first-order rate constant for the CK reaction by 50%. Measured CK reaction velocity decreased by 71%. The reduced ability to increase cardiac performance in response to increasing [Ca2+]o in hearts with lower CK reaction velocity was reproduced in part by feeding a separate group of turkey poults beta-guanidino-propionic acid to specifically reduce CK reaction velocity by decreasing guanidino substrate concentration. These hearts had normal baseline performance but blunted contractile reserve. These observations provide further support for the hypothesis that a decrease in energy reserve via the CK system contributes to reduced cardiac function in the failing heart.

Adenosine Triphosphate↗
PubMed1996

Initial experience with tacrolimus rescue therapy in OKT3 resistant rejection.

Follow-up of 9 renal transplant recipients who were converted from cyclosporin A to tacrolimus (FK506) as recue therapy for intractable rejection is described. All patients initially received a cyclosporin A based immunosuppression. They developed biopsy proven acute rejections 22 +/- 11 days after transplantation which did not resolve by i.v. steroids and subsequent OKT3. Fifty-three +/- 11 days post transplantation the patients were converted from cyclosporin A to tacrolimus. After conversion to tacrolimus 6 patients developed a stabile transplant function. One transplant recipient who initially responded to tacrolimus lost his graft due to a chronic rejection 9 months following conversion. Two patients with never functioning kidneys remained on dialysis despite tacrolimus therapy. After conversion no serious adverse events occurred and only a slightly increased infection rate and hyperglycemia were noted as major side effects of tacrolimus. Tacrolimus rescue therapy was effective in treating acute renal allograft rejection unresponsive to steroids and OKT3. Tacrolimus rescue therapy was not accompanied by a substantial rise in complications. Patients with never functioning kidneys did not seem to benefit from tacrolimus rescue therapy.

Adult↗
PubMed1996

[Is hemithyroidectomy as standard intervention of suspicious puncture cytology justified?].

Since 1989, the operative treatment of 65 patients with suspicious fine-needle aspiration cytology of solitary thyroid nodules has been decided on individual clinical criteria such as the patient's history and morphology of the remaining thyroid tissue. Finally, 9 carcinomas were seen amongst 37 hemithyroidectomy specimens, out of 28 resected thyroid glands 2 were papillary microcarcinomas, whereas the others were benign specimens up until now. Despite a comparatively low perioperative morbidity of the hemithyroidectomy, we see thyroid resections justified in cases of suspicious cytology.

Adenocarcinoma, Follicular↗
PubMed1995

31P nuclear magnetic resonance spectroscopic imaging of regions of remodeled myocardium in the infarcted rat heart.

BACKGROUND: The clinical course of a patient with a myocardial infarction (MI) depends largely on the ability of the noninfarcted region to remodel and compensate for the loss of the infarcted region. Previous studies have shown that the remaining viable myocardium remodels morphologically, functionally, and biochemically. The purpose of this study was to define the regional distribution of the biochemical remodeling that occurs after MI in rat hearts by use of a technique that could be applied noninvasively to human subjects. METHODS AND RESULTS: Infarcts of the left ventricular apex and anterolateral wall were induced by occluding a coronary artery. Eight to 10 weeks after infarction, one-dimensional chemical shift imaging (CSI) was used to obtain 31P nuclear magnetic resonance (NMR) spectra of eight 2.5-mm-thick cross-sectional slices along the long axis (from base to apex) of isolated buffer-perfused rat hearts. Regional ATP and phosphocreatine (PCr) contents were compared in remodeled versus normal (sham) myocardium. Spin-echo 1H MR images identified the mass of each slice, allowing calculations of metabolite amount per unit myocardium in each slice. 1H MR images identify the hypertrophy of remodeled myocardium but do not discriminate between scar and viable tissue. In contrast, 31P CSI does distinguish viable tissue. Compared with shams, there was less 31P signal in the slices distal to the occlusion containing mainly scar tissue and increased signal intensity in slices proximal to the occlusion because of myocyte hypertrophy. The ATP signal intensity changed in direct proportion to the viable tissue mass in the slice, suggesting that the amount of ATP per unit mass in viable remodeled myocardium is the same as that of the shams. In contrast, the amount of PCr per unit mass in remodeled myocardium decreased. This decrease is uniform across the slices, correlates with infarct size, and parallels a similar decrease in tissue creatine content. CONCLUSIONS: 31P CSI of post-MI hearts shows that (1) PCr decreases uniformly (ie, independent of the distance from the scar) in the noninfarcted remodeled myocardium, and its amount inversely correlates with infarct size; and (2) the ATP signal provides a profile of viable myocardium and is a biochemical marker of morphological remodeling and hypertrophy that has occurred in noninfarcted regions. Thus, 31P CSI provides both a marker that tissue injury has occurred (decreased PCr) and a marker of the extent of remodeling in response to injury (ATP distribution) in a single set of noninvasive measurements.

Adenosine Triphosphate↗
PubMed1995

[The effect of donor and recipient ages on the results of kidney transplantation].

In a retrospective study of 814 patients (349 women, 465 men) who had received their first kidney transplant, early function rate as well as transplant and patient survival rates were determined in relation to age (up to 50 years: 530; 51-55 years: 140; 56-60 years: 83; over 60 years: 61). The same rates were also grouped by donor age (> 16 years, 68 patients; 16-40 years, 387; 41-50 years, 165; 51-60 years, 144; over 60 years, 50). The 5-year transplant function rate fell significantly with increasing donor age (P = 0.0001) from 78% (16-40 years) to 47% (over 60 years). For the same age groups the proportion of transplants which never resumed their function rose from 8 to 28%. Age of recipient had no influence on early function and 5-year transplant function rates. Thus, regardless of the recipient's age, higher donor age is an independent risk factor for early and late results after transplantation.

Adolescent↗
PubMed1995

Enalapril treatment increases cardiac performance and energy reserve via the creatine kinase reaction in myocardium of Syrian myopathic hamsters with advanced heart failure.

BACKGROUND: Converting enzyme inhibitor treatment of congestive heart failure slows progression to failure and reduces mortality rate. It is known whether these benefits are due solely to improved hemodynamics or also to improved myocyte energetics. This study examines the effect of enalapril treatment on both isovolumic contractile performance and its biochemical correlate, flux through the creatine kinase (CK) system, in an animal model of severely failing myocardium. METHODS AND RESULTS: Seven-month-old Syrian cardiomyopathic (TO-2 strain) and normal golden Syrian (FIB strain) hamsters were each randomly assigned to one of three groups supplied daily with either no, low (25 mg/kg body wt), or high (100 mg/kg body wt) doses of enalapril for 12 to 14 weeks. At 10 months of age, all substrates and products and flux through the CK reaction were measured in isolated perfused hearts by 31P magnetization transfer and chemical assay. Compared with normal hamsters, the myopathic hamsters exhibited significantly lower body weights and higher biventricular heart weights, which were partially reversed by drug treatment. The Langendorff-perfused hearts showed decreased isovolumic contractile performance with identical load conditions. This was partially reversed by drug treatment. In the failing hearts, the following substrate and product concentrations and enzyme activities were decreased compared with nonfailing hearts but were unchanged by drug treatment: ATP (-28%), phosphocreatine (-48%), free creatine (-64%), ADP (-51%), and CK (-34%, primarily MM isoenzyme). Flux through the CK reaction for the untreated cardiomyopathic hamster hearts was decreased by 67%, and this decrease was almost completely reversed by enalapril treatment. The increased CK flux is due to an increase in the rate constant for the reaction, since substrate concentrations are unchanged, and is not predicted by the rate equation. In enalapril-treated failing hearts, phosphoryl transfer via the CK reaction increased with contractile performance. This was not observed in the nonfailing hearts, in which energy reserve is adequate to support changes in contractile performance. CONCLUSIONS: Decreased flux through CK reaction leads to decreased capacity for ATP synthesis and may contribute to decreased contractile performance in cardiomyopathic hamster hearts. Enalapril treatment results in increased phosphoryl transfer through the CK reaction in failing myocardium, and this increase is coupled to improved cardiac performance. Decreased CK flux in failing hearts is due to a combination of decreased Vmax and lower guanidino pool; this mechanism fails to explain changes in CK flux in enalapril-treated failing hearts.

Animals↗