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H Witt

Publications and source records attributed to H Witt.

At least 19 recordsLinked to original sources
PubMed1995

Site-directed mutagenesis of cytochrome c oxidase reveals two acidic residues involved in the binding of cytochrome c.

Site-directed mutagenesis in subunit II of the cytochrome c oxidase (haem aa3) from Paracoccus denitrificans reveals that two carboxylic residues, Glu-246 and Asp-206 (corresponding to 198 and 158 in the bovine subunit II), are involved in the binding of cytochrome c. Spectrophotometric and polarographic measurements with the isolated enzymes of both mutant strains show a strongly reduced activity compared to wild-type oxidase, with the overall catalytic capacity (kcat/KM) of both mutants decreased about 8-fold. EPR spectra reveal no significant differences between the wild-type and the mutant enzymes, indicating that neither residue contributes significantly to the structure of the CuA centre. We conclude that Glu-246 and Asp-206 constitute an essential part of the binding site for cytochrome c.

Binding Sites↗
PubMed1995

Quantitative endoscopic classification of esophagitis by means of computerized image processing. Part 1: Theoretical background.

The potential sources of error for quantitative mapping of pathological areas in tubular organs are investigated mathematically and discussed. The first of the main errors stems from a predominance of red in the illuminating light reflected and re-reflected from the side wall of the tubular organ as compared with the white illuminating light coming directly from the light source in the endoscope. A mathematical model for this has been constructed to define an allowed interval of observation distance. The second error is due to geometrical projection, and results from the fact that more distant parts of the inside of a tube subtends a smaller solid angle than closer parts.

Esophagitis↗
PubMed1994

The significance of mucosal staining for the endoscopic diagnosis of chronic esophagitis as assessed in biopsy findings.

A total of 115 patients with clinical signs of esophagitis were examined by endoscopy and mucosal biopsy combined with Lugol solution. Overall, 175 mucosal areas (105 stained and 70 unstained) were subjected to histopathological examination. The correlation between the staining properties of the esophageal mucosa and the histopathological diagnosis resulted in a diagnostic sensitivity of 51.9%, a specificity of 70.2%, a positive predictive value of 60.0% and a negative predictive value of 62.9% for Lugol combined endoscopy. Lugol combined endoscopy did not appear to result in any improvement in the diagnosis or staging of reflux esophagitis in our study.

Adult↗
PubMed1993

Genes encoding eleven subunits of photosystem I from the thermophilic cyanobacterium Synechococcus sp.

We have isolated the genes encoding 11 photosystem I (PSI) subunits from Synechococcus sp., from which this reaction center has been crystallized. The recombinant DNAs, including psaA, psaB, psaC, psaD, psaE, psaF, psaI, psaJ, psaK and psaL, were obtained by heterologous hybridization with probes from appropriate cDNAs or genes from spinach and Synechocystis sp. PCC 6803, or with synthetic oligodeoxyribonucleotides. Genes psaA/psaB, psaF/psaJ and psaL/psaI are each closely linked. The open reading frames predict polypeptides of 83 kDa (subunits Ia and Ib, encoded by genes psaA and psaB, respectively), 15.4 kDa (II, psaD), 17.7 kDa (III, psaF), 8.4 kDa (IV, psaE), 8.8 kDa (VII, psaC), 4.6 kDa (VIII, psaI), 4.8 kDa (IX, psaJ), 8.5 kDa (X, psaK) and 15.5 kDa (XI, psaL). A novel subunit (XII, psaM) was also identified. Subunits II, III, IV and VII seem to be peripheral, while the others seem to be intrinsic components of the reaction center. These data imply a striking similarity of cyanobacterial and eukaryotic PSI. All subunits studied are encoded by single-copy genes which seem to be transcribed into monocistronic (psaC, psaD, psaC, psaK) or dicistronic (psaA/psaB, psaF/psaJ, psaL/psaI) RNA species. Subunit III is translated as a 17.7-kDa precursor, including a transit peptide of 23 amino acid residues. This is consistent with its location in the thylakoid lumen.

Amino Acid Sequence↗
PubMed1993

Efficacy of pyrimethamine/sulfadoxine in the prevention of toxoplasmic encephalitis relapses and Pneumocystis carinii pneumonia in HIV-infected patients.

The efficacy and safety of 25 mg pyrimethamine plus 500 mg sulfadoxine given twice a week in preventing relapses of AIDS-related toxoplasmic encephalitis was evaluated in an open study. The 56 HIV-infected patients evaluated had responded to intensive treatment with pyrimethamine/clindamycin prior to starting the present prophylactic regimen. Four patients (7 %) experienced relapse while on pyrimethamine/sulfadoxine. The probability of freedom from relapse was > 90% for 12 months and > 80% for 24 months. Side effects comprised mild or moderate allergic reactions which occurred in 23 patients (41 %), leading to discontinuation in four patients (7%). Forty-nine of the 56 patients did not have a history of Pneumocystis carinii pneumonia and did not receive antiparasitic prophylaxis other than pyrimethamine/sulfadoxine; two of them (4 %) developed pneumocystosis. The probability of freedom from pneumocystosis was about 90 % for 24 months. Pyrimethamine/sulfadoxine twice a week appears to be a promising regimen for prevention of toxoplasmic encephalitis, and also appears to provide protection against Pneumocystis carinii pneumonia. Although allergic reactions are usually mild and disappear on continuation, they may limit the value of this regimen.

AIDS-Related Opportunistic Infections↗
PubMed1991

[Abdominal organ-transcending tumors with special reference to peritoneal carcinosis. CT versus the surgical site].

In 41 patients with a histologically confirmed peritoneal carcinomatosis (n = 29) or lymphangiomatosis (n = 12) the preoperative CT investigations of the abdomen were compared with intraoperative findings. CT findings were differentiated between direct or indirect signs. The sensitivity of the various CT signs of peritoneal carcinomatosis or lymphangiomatosis was between 66 and 100%. Abdominal CT studies proved to be a reliable preoperative method if the findings were examined closely. A precise review even of indirect signs is of high diagnostic value.

Abdomen↗
PubMed1990

[Histopathologically verified cerebral CT findings in AIDS].

Computer tomographic and histopathological findings in 55 patients who died of the complications of acquired immunodeficiency syndrome, were reviewed retrospectively. In 23 patients (42%) an increased space of the internal or external cerebral spinal fluid was diagnosed. 20 patients (36%) had focal lesions. We differentiated between single, multiple and ring-shaped lesions with contrast enhancement and hypodense lesions. In 12 cases (22%) no CT abnormalities were found. Focal lesions proved to be secondary to toxoplasmosis in 85%. Single lesions were never caused by toxoplasmosis.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Osteomyelitis due to Cryptococcus neoformans in advanced age. Case report and review of literature.

In an 84-year-old man cryptococcosis with a pronounced osteomyelitic course (involvement of a rib, two thoracic vertebrae, the sacrum and a femur) was diagnosed histologically post mortem, thus directing attention to cryptococcosis in advanced age. The presumptive chronic course of the Cryptococcus neoformans (Cr. n.) infection in this patient was ascribed to chronic kidney failure, diabetes mellitus and chronic obstructive lung disease. Special reference is made to the mycological and radiological diagnosis of cryptococcosis of the bones as well as to its pathogenesis, therapy and epidemiology.

Aged↗
PubMed1990

[Comparison of computerized tomography and pathologic-anatomic findings of the abdomen in HIV infection].

In a retrospective study the results of abdominal computed tomography (CT) from 48 patients, who died of the complications of HIV infection, were compared with those obtained at autopsy. The CT diagnosis was confirmed at autopsy in 39 cases (81.3%). In nine patients CT results did not correlate with the postmortal findings. This was caused by lack of cooperation, cachexia and the time between the last CT study and the death of the patients. Nevertheless, CT with its standardised imaging planes is an important method for diagnosing and monitoring HIV-related diseases of the abdomen.

Adult↗
PubMed1990

[Quantitative flow determinations in the superior femoral artery and the popliteal artery using angiodynography (color-coded duplex sonography) before and after percutaneous transluminal laser angioplasty].

The primary angiographic PTLA-success correlates with the angiodynographically measured blood flow. 24 hours after the treatment the measured flow values in the AFS and AP allow prognoses: 1. Flow volumes in the AP less than 15 ml/min do not allow successful PLTA-therapy. 2. Slight clinical improvement can be expected for flow values greater than 50 ml/min in the AFS and between 20 and 30 ml/min in the AP. 3. AP-values greater than 30 ml/min correlate in this pilot investigations with an excellent clinical result 4 months after intervention.

Angioplasty, Laser↗
PubMed1990

[Cavernous hemangioma of the maxillary sinus].

Cavernous haemangioma of the paranasal sinuses is very rare. We describe the X-ray and CT findings in a case of cavernous haemangioma which originated from the mucous membrane of the maxillary sinus and eroded the bony boundary of the sinus.

Diagnosis, Differential↗
PubMed1989

[Limits of the diagnostic capability of pulmonary digital subtraction angiography].

Digital subtraction pulmonary angiography was performed in 70 patients suspected of having pulmonary emboli. In 35 patients this diagnosis proved to be correct. The technical quality of all ECG-gated studies was scored and was found to be satisfactory in 31 patients (44%), moderate in 23 (33%) and unsatisfactory in 16 patients (23%). This was mainly due to the lack of patient cooperation. In patients with direct injection into the pulmonary artery (27%) the motion artifacts were less disturbing. We therefore suggest that even when using ECG-gated acquisitions, the injection should be performed into the pulmonary artery to overcome technical problems in the diagnosis of pulmonary embolism.

Adult↗
PubMed1989

[2-dimensional CT arthrotomography in the postoperative follow-up of a new anterior cruciate ligament plasty].

Fifty-eight patients underwent intraarticular reconstruction of the anterior cruciate ligament. This was performed by using an autogenous transplant from the mid portion of the patellar ligament with a proximal and distal bone block, as described by Hertel. For comparison with the conventional X-ray examination, HRCT was performed to study the early postoperative results. In four patients (7%) dislocation of the bone block in the femoral condyle was seen. Two-dimensional reconstruction proved to be a satisfactory method for demonstration of the exact position of the autogenous transplant in both coronary and sagittal planes.

Adolescent↗
PubMed1988

[Angiodynography: a new imaging procedure in the ENT field].

A new diagnostic imaging is presented which demonstrates the blood flow in addition to the usual ultrasonic image. Motion pictures show both the direction of the blood flow in different colours and the speed in variable intensity of the colour. Thus vessels of only 0.5 mm diameter may be identified. In otorhinolaryngology, the vascular supply of space-occupying lesions can be determined quantitatively in a noninvasive way. Lymphomas may be differentiated from vascular tumours and malformations. Preoperatively, vessels adjacent to the tumour may be identified. This method is particularly useful in the evaluation of thyroid and salivary gland disorders.

Blood Flow Velocity↗