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Biomedical subjects

A Schwarz

Publications and source records attributed to A Schwarz.

At least 19 recordsLinked to original sources
PubMed1992

EEG-brain mapping. A method to optimize therapy in schizophrenics using absolute power and center frequency values.

In this study EEG-spectral parameters like mean alpha-power values and center frequency values are computed as maps and compared using significant probability mapping. The parameters are used to describe changes of the functional state of the brain after neuroleptic depot injection (Haldol-Decanoate) in schizophrenic patients. The absolute alpha-power increased significantly (p < 0.01), especially within the first week after injection mostly in the left hemispheric regions. The center frequency decreased most significantly (p < 0.02) between the first and second week after haldol depot injection at the right occipital regions. Both parameters are efficient to describe functional changes correlated with clinical symptomatology, even 3-5 days earlier. Thus, EEG power and center frequency mapping can be used very efficiently to estimate the optimal time between sequential neuroleptic depot injections.

Adult↗
PubMed1992

Prevalence and classification of anemia in elective orthopedic surgery patients: implications for blood conservation programs.

We audited 281 consecutive orthopedic patients scheduled for surgery for whom blood type/cross-matching was requested over a 6-month period. One hundred and sixty-two patients predonated autologous blood at University Hospitals of Cleveland, and 34 (21%) of these were anemic [hematocrit (Hct) less than or equal to 39%] at initial donation. Twelve (35%) of these 34 anemic autologous blood donors subsequently received homologous blood. In contrast, 18 (15%) of 128 nonanemic autologous blood donors received homologous blood (p = 0.05). In 119 patients who did not donate autologous blood, 39 (33%) were anemic at admission. Of these, 22 (56%) received homologous blood. In the 80 remaining nonanemic patients, 33 (41%) received homologous blood (p = 0.119). Analysis of discharge Hct indicates that 31 (12%) of 263 evaluable patients were possibly transfused inappropriately. The anemias of a cohort of 30 autologous donors were analyzed: 5 had rheumatoid arthritis without iron deficiency. Nine (30%) others had evidence of iron deficiency. Sixteen (53%) had an unclassified anemia of chronic disease. We conclude: (1) the high rates of homologous blood exposure indicate a need for innovative blood conservation strategies in anemic autologous blood donors; (2) the prevalence of anemia and the high rates of homologous blood exposure in anemic patients who did not donate autologous blood demonstrate a need for early recognition and treatment in order to procure autologous blood and reduce homologous blood exposure; (3) the presence of inappropriate autologous and homologous transfusions demonstrates a need for more effective physician education programs that emphasize 'no blood transfusion' as an alternative to enhance blood conservation effectiveness.

Anemia↗
PubMed1992

Analgesic nephropathy and renal transplantation.

Analgesic nephropathy was the most frequent diagnosis in 324 haemodialysis patients (30%) and the second most frequent diagnosis in 900 transplant patients (17%) at the Klinikum Steglitz, Berlin. Analgesic patients were the oldest group among haemodialysis and transplanted patients; the analgesic patients on haemodialysis were significantly older than the transplanted analgesic patients (55.9 +/- 11.2 versus 50.5 +/- 7.5 years, P = 10(-6)). Patient and graft survival under cyclosporin treatment are not statistically different in 125 transplantations of 109 patients with analgesic nephropathy compared to 508 transplantations of 423 patients with other renal diseases (5-year patient survival, 83.3 +/- 5.1% versus 88.4 +/- 2.4%; 5-year graft survival, 53.5 +/- 7.4% versus 56.8 +/- 3.8%; NS). Acetaminophen in urine was found in two of 30 analgesic and in one of 54 other patients with a functioning transplant (6.7% versus 1.9%; NS). As a sign of compliance, the mean cyclosporin trough level of 17 patients with analgesic nephropathy did not differ significantly from that of 14 patients with polycystic kidney disease (136.4 +/- 16.4 versus 139.4 +/- 17.3 ng/ml; NS), nor did the mean standard deviation of the individual measurements (36.7 +/- 36.8 versus 27.5 +/- 20.7 ng/ml; NS). Urothelial carcinoma was significantly more frequent in patients with analgesic nephropathy than in those with other renal diseases despite cystoscopy and retrograde pyelography before transplantation (3.7% versus 0.32%; P = 0.001). Vascular disease was the cause of death in 19 of 44 analgesic transplant patients who died (43.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[A phosphine-substituted diphosphonic acid (HMPD) for improved scintigraphic detection of bone lesions].

Although the radiopharmaceuticals used for bone scintigraphy are of very high quality, the search for an "ideal" agent continues. To optimise the detectability of bone lesions, we analysed 244 different 99mTc-labeled phosphonates in animal experiments. In osteosarcoma-carrying rats 99mTc-labeled 1-Hydroxy-3-methyl-phosphinic-1, 1-propanediphosphonic acid (HMPD) was shown to produce the best lesion/normal bone ratio. 99mTc-MDP was used as reference. The ratio was found to be 1.28 for 99mTc-HMPD. The transferability of our results in animals to the situation in man was studied in 10 patients with bone metastases. There was for 99mTc-HMPD an improvement of the lesion/normal bone ratio by more than 60% but also an additional reduction of the soft tissue contrast by about 40%. 15% of the metastases were detected by scintigraphy using 99mTc-HMPD only and not with 99mTc-MDP. The new agent should make possible a better and earlier discrimination of bone lesions in the scintigram.

Aged↗
PubMed1992

[Binding of the monoclonal antibody BW 250/183 to human granulocytes].

Lately, the specific binding of appropriate monoclonal antibodies to human granulocytes has been used for the scintigraphic detection of inflammatory foci. Using the antibody BW 250/183 we studied the underlying binding kinetics. As an important requirement for a specific cell binding it has been shown that the labelling procedure does not change the immunoreactivity of the antibody. An affinity constant of 2 x 10(9) l/mol has been calculated from binding studies. Usually, 0.25-1.0 mg of the 99mTc-labelled antibody are applied per patient. In the present study an equilibrium in blood appeared quickly after intravenous application; at steady state about one fourth of the activity was cell-bound. The rest of the activity circulated in the plasma in the form of labelled IgG and was able to react directly with those granulocytes which were already accumulated in the inflamed area. Even a drastic reduction of the applied protein mass did not change this equilibrium. The law of mass action seems not to be directly applicable to this problem. Interferences with components of the plasma can be excluded as explanation for this behaviour. After application of in-vitro labelled granulocytes from which unbound antibodies were removed completely by washing, an identical steady state was observed within 10 min after injection; however, in this situation the intravasal residence time of activity increased distinctly.

Antibodies, Monoclonal↗
PubMed1991

Determination of human prothrombin activation fragment 1 + 2 in plasma with an antibody against a synthetic peptide.

The present investigation describes a novel approach to prepare a specific antibody against prothrombin activation fragment 1 + 2 (F 1 + 2). The antibody discriminates between native prothrombin and F 1 + 2 in plasma. A synthetic peptide from the negatively charged region of F 1 + 2, which becomes the carboxy-terminal sequence after cleavage of prothrombin by factor Xa, was used for immunization of rabbits. Obtained antiserum was immunopurified and an enzyme-linked immunosorbent assay (ELISA) was constructed for determination of F 1 + 2. The test system follows the sandwich principle and uses two different antibodies directed against F 1 + 2 and prothrombin, respectively. The ELISA was calibrated with purified F 1 + 2 added to F 1 + 2-poor plasma. The lower limit of sensitivity of the assay was 0.02 nmol/l. Coefficients of variation of 6.9 to 10.4% (intraassay) and 6.7 to 11% (interassay) were found for F 1 + 2 concentrations between 0.08 and 4.9 nmol/l. A reference range from 0.32 to 1.2 nmol/l was calculated from 95 healthy donors (mean value +/- SD: 0.67 +/- 0.19 nmol/l). In patients with deep vein thrombosis (n = 7) confirmed by phlebography and in patients with pulmonary embolism (n = 8) confirmed by lung scan, F 1 + 2 levels were found up to 1.5 to 9.5 nmol/l. In plasma samples of patients under oral anticoagulant therapy in the stable state F 1 + 2 concentrations were found to be in the range of 0.08 to 0.5 nmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Formation of peptide bonds by carboxypeptidase c from orange leaves.

Carboxypeptidase c partially purified from orange leaves was studied as a catalyst for enzymatic peptide synthesis. Various N-protected ester- and nucleophile compounds were evaluated in order to determine the substrate specificity. For further characterization of the synthetic reaction, optimum pH and the influence of the N-terminal protecting group were studied. Kinetic investigations revealed considerable differences in Km and Vmax for the nucleophile when the N-terminal protecting group of the substrate was varied.

Amino Acid Sequence↗
PubMed1991

Recurrent and de novo renal disease after kidney transplantation with or without cyclosporine A.

We evaluated the clinical course of 700 renal transplantations, including 1,305 transplant histologies performed in 611 patients between 1970 and 1988, to estimate the influence of cyclosporine A (CsA) after kidney transplantation on the incidence of recurrent or de novo renal disease. Primary renal disease recurred in 11 of 583 functioning transplants (1.9%) with transplant loss in seven patients (1.2%): focal segmental glomerulosclerosis (FSGS, three patients); membranous glomerulonephritis (GN, one patient); mesangiocapillary GN (one patient); rapidly progressive IgA nephropathy (one patient); hemolytic-uremic syndrome (HUS, three patients); and oxalosis in two transplants (one patient). De novo renal disease occurred in six patients (1.0%), including mesangiocapillary GN type I (three patients); nonpurulent focal GN in septicemia (one patient); HUS (one patient); and nodular glomerulosclerosis in steroid diabetes (one patient). De novo membranous GN was seen in 14 additional cases (2.4%). No statistically significant difference could be established between the treatment groups without (n = 225) and with (n = 358) CsA in recurrent and de novo renal disease (n = 7/225 v 10/358, NS); in recurrent and de novo GN (n = 4/225 v 6/358, NS); in recurrent FSGS (n = 1/7 v 2/8, NS); in recurrent and de novo HUS (n - 1/1 v 2/7, NS); and in de novo membranous GN (n = 7/225 v 7/358, NS). Transplant loss by recurrent and de novo GN was higher without than with CsA (n = 4/4 v 1/6, P = 0.004). On the basis of our investigation, we conclude that recurrent and de novo renal disease in the transplant occur rarely and are not prevented by CsA. However, even if the incidence of transplant GN is unchanged by CsA treatment, its clinical course seems to be mitigated. CsA treatment also does not increase the incidence of HUS.

Adolescent↗
PubMed1991

Generation of bispecific monoclonal antibodies for two phase radioimmunotherapy.

A two phase radioimmunotherapy based on bispecific MAbs in which one arm recognises a tumour antigen and the other a radiolabelled chelate, may prove more effective in the treatment of carcinomas than currently available immunotherapies. To establish this system we first showed that penetration into human carcinoma xenografts as well as long term retention of intact MAb outside the carcinoma cells can be obtained. Epitope saturation was not obtained however, despite the large MAb doses injected i.v. for 10 days. We then generated hybridomas producing high avidity anti-metal chelate MAbs (anti-DTPA-Y). These hybridomas were fused with hybridomas producing MAbs against CEA or GIT-mucin, and stable bispecific MAb producing quadromas were obtained. For the anti-GIT-mucin x anti-chelate MAb a purification procedure based on double anti-idiotype affinity chromatography was shown to result in greater than 95% pure bispecific immunoreactive MAb. Comparative in vivo stability studies profiled DTPA-Y as the chelate of choice for in vivo application.

Animals↗
PubMed1991

Involvement of neutrophils in postischaemic damage to the small intestine.

Haemorrhagic mucosal lesions are produced during intestinal ischaemia and after reperfusion probably mediated by oxygen radicals. Oxygen radicals react with cell membrane lipids and induce cell damage by peroxidation and induce accumulation of polymorphonuclear leucocytes in the tissue. The aim of the study was to elucidate the involvement of polymorphonuclear leucocytes in post-ischaemic intestinal damage. Intestinal ischaemia was induced in cats by partial occlusion of the superior mesenteric artery. Samples from the small intestine were excised before and at the end of the two hour hypotensive period as well as 10 minutes and 60 minutes after reperfusion. Conjugated dienes, myeloperoxidase, and the purine metabolites were determined in the samples. The tissue was also examined histologically. Seven cats were treated before reperfusion with a monoclonal antibody (IB4) which inhibits leucocyte adherence to endothelial cells and its subsequent activation. After reperfusion myeloperoxidase activity increased and the ischaemic mucosal lesions worsened significantly. IB4 treatment prevented an increase in post-hypotensive myeloperoxidase activity and attenuated the normally observed severe mucosal lesions. We conclude that the severe post-ischaemic lesions are induced by polymorphonuclear leucocytes. Such mucosal injury may be appreciably reduced by blocking leucocyte adherence with IB4.

Animals↗
PubMed1991

Preparative-scale enzyme-catalyzed peptide synthesis using solubilizing N-terminal protecting groups.

Several amino acid derivatives with the negatively charged N alpha-protecting groups Maleyl (Mal) and Citraconyl (Cit) were synthesized and used in enzyme-catalyzed peptide synthesis. Compared to commonly used alpha-amino protecting groups in chemical peptide synthesis (Z, Fmoc, Boc, etc.), these charged protecting groups strongly increase both water solubility of different aromatic amino acid derivatives and activities of synthesis reactions. As a consequence of the solubilizing effect, we used these groups in the kinetically controlled peptide synthesis choosing kyotorphin (tyrosyl-arginine) as a model peptide. With Mal-Tyr-OEt as substrate and Arg-OEt as nucleophile, we succeeded in the alpha-chymotrypsin-catalyzed production of about 12 kg of Tyr-Arg (50.4% overall yield) in a 300 l batch experiment.

Dipeptides↗
PubMed1990

Imaging rheumatoid arthritis specifically with technetium 99m CD4-specific (T-helper lymphocytes) antibodies.

CD4 expressing T-lymphocytes are involved in the pathogenesis of rheumatoid arthritis, so the possibility of using radiolabelled CD4-specific antibodies to localise diseased joints was studied. Prospectively six patients with rheumatoid arthritis were investigated. Five of them received 200-300 micrograms of a 555 MBq technetium 99m CD4-specific antibody (MAX.16H5) and were examined with three phase bone scans. Max.16H5 (IgG1) was labelled according to the mercaptoethanol (Schwarz) method. Lymphocytes of one patient were isolated on a Ficoll-Hypaque gradient and labelled with the antibody in vitro. Scans were performed 1.5 h, 4 and 24 h post injection in anterior and posterior views. In all patients, diseased joints could be clearly imaged at as early as 1.5 h. The localisation of the diseased joints correlated (P less than 0.01) with the clinical signs, with the early methylene diphosphonate (MDP) scan (P less than 0.01) and only weakly with the late bone scan (P greater than 0.05). According to these data we conclude that 99mTc-labelled CD4-specific antibodies specifically image actively diseased joints in rheumatoid arthritis.

Antibodies, Monoclonal↗
PubMed1990

[Left hemispheric site of EEG findings in patients with schizophrenic psychoses].

It was the aim of our study to examine the interhemispherical and extrahemispherical integration that is possibly disturbed in patients suffering from schizophrenic psychoses, using an easy method of EEG performance spectral analysis. For this purpose, the EEG at rest and the functional EEG were determined in 69 schizophrenic patients (ICD) and 22 healthy subjects and the EEG reactivity was calculated. Differences especially in alpha-2 reactivity were seen both intrahemispherically and interhemispherically. This supports the concept of left hemispheric dysfunction in patients suffering from schizophrenic psychoses.

Adult↗