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Biomedical subjects

M Beer

Publications and source records attributed to M Beer.

At least 181 records · Page 10Linked to original sources

Performance appraisal: dilemmas and possibilities.

Citing avoidance by the supervisor and defensiveness from the subordinate as the two main barriers to effective performance appraisal, the author suggests ways to minimize both. The emphasis is on discussing performance evaluation in a nonevaluative manner.

Conflict, Psychological↗

[Phase-II-study with vindesine (desacetyl-vinblastine-amide-sulfate) in advanced malignant diseases].

53 patients with advanced and measurable cancerr were treated with vindesine in doses of 3 mg/m2 (pretreated) and 4 mg/m2 (non pretreated) i.v. once weekly. 48 patients are evaluable for response: of 14 patients with squamous cell carcinoma of the lung, 1 partial remission (PR), 1 minor response (MR) and 1 no change (NC) were observed. In 5 patients with large cell carcinoma of the lung: 1 NC. In 3 with adenocarcinoma of the lung: 1 MR. One patient with nasopharyngeal carcinoma had progressive disease. Stable disease was observed in a patient with carcinoma of the tongue and in a patient with adenocarcinoma of the esophagus. Four patients with colorectal carcinoma had progressive disease. One MR was observed in a patient with breast cancer, while all of the other 3 patients had progressive disease. One carcinoma of the penis was stable. One MR was observed in a patient with Hodgkin's disease. One PR was observed in a case with no-Hodgkin's lymphoma. A patient with acute leukemia had progressive disease. Among 9 patients with malignant melanoma, 3 had an MR and 1 patient had stable disease. A patient with fibrosarcoma had progressive disease. Observed toxicity included leukopenia, thrombocytopenia, anemia, paresthesias, constipation, jaw pain, nausea, stomatitis, alopecia, loss of taste, pruritus and skin rash, weakness and fatigue.

Adenocarcinoma↗

Effects of obstruction on single-kidney function: clinical and experimental results with 131I-hippurate and 99mTc-DMSA.

In 35 patients, renography with 131I-o-hippurate (OIH) and static renal imaging with 99mTc-dimercaptosuccinic acid (DMSA) were used to measure differential renal function (DRF). The results were compared. Depth correction was applied in both methods. In non-obstructed kidneys (19 patients), both methods revealed nearly identical kidney function (r = 0.98). For completely obstructed kidneys (16 patients), OIH gave a significantly better DRF (14 ml/min) than DMSA. This small difference was of no clinical value. Because DMSA is reported to give unreliable results in unilateral obstructed kidneys, the right ureter was ligated in 8 dogs for 10 days and DRF was measured before and after opening an ureteral fistula. The difference in DRF was about 1% and could be accounted for by the amount of urinary radioactivity collected from the pelvic system after the ligature had been opened. Although DMSA appears to give reliable values in determining DRF, even in obstructed kidneys, OIH is preferred since total clearance values and postrenal urinary dynamics can be determined simultaneously.

Animals↗

Osmium-labeled polynucleotides: reaction of osmium tetraoxide, with poly-1,N6-ethenoadenylic acid.

Osmium tetraoxide, in the presence of ligands such as pyridine and bipyridine, adds across the etheno bridge of 1,N6-etheno-9-methyladenine and poly-1,N6-ethenoadenylic acid. The Os:P ratio in the labeled polynucleotide was approximately equal to 1 when bipyridine was used as the stabilizing ligand. A similar study with polycytidylic acid, which had been partially modified with chloroacetaldehyde so that some bases were converted to 3,N4-ethenocytosine, gave an OS:P ratio of approximately equal to 1.3. Calf-thymus DNA, in which the adenine and cytosine bases were modified by chloroacetaldehyde, gave an Os:P ratio of approximately equal to 1 after 24 h. These results suggest that 3,N4-ethenocytosine will add two Os labels.

Adenosine Triphosphate↗

Electron microscopic determination of the binding sites of ribosomal proteins S4 and S8 on 16S RNA.

Specific complexes.early in the assembly of Escherichia coli ribosomes were examined in the electron microscope. Complexes between ribosomal protein S4 or S8 and 16S RNA were fixed gently with formaldehyde and then denatured for protein-free spreading. Binding of each protein was found to preserve an easily recognized configuration in the RNA that allows the sites of protein binding to be determined. S8--16S RNA complexes have a single hairpin loop near the middle of the 16S RNA, 798 +/- 21 bases from one end and 657 +/- 26 bases from the other. S4-16S RNA complexes have two adjacent loops at one end with 250--450 bases. This structure probably arises from the simultaneous binding of S4 to three noncontiguous sites on the RNA. Measurements of these complexes place the binding sites near the 5' end, at more than one site 250--585 nucleotides from the 5' end and 645 +/- 45 bases from the 3' end. The latter site has not been recognized previously as a distinct S4 binding site. This approach allows the binding sites to be determined without knowledge of the nucleotide sequence and gives insight into the configuration of the rRNA in the assembling ribisome.

Binding Sites↗

Vitamin-D metabolism in nephrotic syndrome.

Plasma concentrations of 25-hydroxy-cholecalciferol (25-OHD3) and vitamin-D-binding globulin (V.D.B.G.) were significantly reduced in ten nephrotic subjects. V.D.B.G., which is undetectable in normal urine, was present in substantial amounts in the urine of each nephrotic subject. Administration of 3H-labelled cholecalciferol to three subjects resulted in the rapid appearance of the labelled vitamin in the urine, mainly as the 25-hydroxylated metabolite bound to V.D.B.G. in amounts which could largely account for the low plasma-25-OHD3. The plasma half-life of 25-OHD3 was substantially reduced in the nephrotic syndrome.

Adult↗

Osmium-labeled polynucleotides. The reaction of osmium tetroxide with deoxyribonucleic acid and synthetic polynucleotides in the presence of tertiary nitrogen donor ligands.

Osmium tetroxide in the presence of pyridine or 2,2'-bipyridine has been found to react completely with the pyrimidine moieties (thymine, uracil, and cytosine) in polynucleotides. Pyrimidine osmate ester moieties, L2OSO4-pyrimidine, were formed. The OSO4 has added across the 5,6 double bond and L=pyridine or 1/2-bipyridine. The pyridine derivatives were not stable and decomposed slowly after the OSO4-pyridine reagent was removed by gel chromatography. Labeled poly(uridylic acid) lost osmium completely during gel chromatography unless the eluent contained a high concentration of pyridine. The products formed between OSO4-bipyridine and polynucleotides were much more stable and the OS label was retained during and after gel chromatography. Both the OSO4-pyridine and OSO4-bipyridine reagents reacted more rapidly than the OSO4-CN-reagent.

Binding Sites↗

[Tubular response to antidiuretic plasma activity in the transplanted kidney (author's transl)].

Reabsorption of osmotically free water (TmcH2O) was studied in 10 patients after renal transplantation. A rising or constant free water reabsorption was observed under hydropenia and increasing tubular solute load. These findings suggest that in the transplanted kidney the functioning nephrons respond in a normal way to plasma ADH-activity. The excretion of plasma-hypotonic urine reflects decreased antidiuretic activity as in overhydration rather than tubular unresponsiveness to ADH. The excretion of plasma-hypertonic urine indicates tubular reabsorption of osmotically free water due to ADH, and this in general rules out overhydration. Daily estimation of urinary and plasma osmolality will be useful in judging the actual state of hydration after renal transplantation.

Blood↗