Serum tyrosinase in malignant disease, its activity, and the electrophoretic patterns of the enzyme as carried by immunoglobulins'.

Serum tyrosinase activity in many persons with metastatic diseases was found to be significantly higher than activity in normal persons. The highest activity was observed in melanoma and breast carcinoma. The electrophoretic patterns of serum tyrosinase, resolved by electrophoresis of a serum tyrosinase fraction followed by incubation of the gel sample with L-dopa, and represented as sets of RF's of melanin bands, were characteristically different in melanoma, breast carcinoma, and certain other diseases. The RF's of melanin and protein bands in the serum enzyme preparations from melanoma patients were concisely defined. Further, some potent serum fractions inhibiting tyrosinase melanogenic activity have been obtained, and the presence of tyrosinase inhibitors in the serum enzyme preparation has also been demonstrated. More detailed exploration of these serum tyrosinase parameters may provide more specific and sensitive detection for certain malignant diseases.

Destruction of the medial forebrain bundle caudal to the site of stimulation reduces rewarding efficacy but destruction rostrally does not.

Rats with an electrode in the medial forebrain bundle (MFB) in or near the ventral tegmental area and another at the level of the rostral hypothalamus sustained large electrolytic lesions at either the rostral or the caudal electrode. The rewarding efficacy of stimulation through the other electrode was determined before and after the lesion. Massive damage to the MFB in the rostral lateral hypothalamus (LH) generally had little effect on the rewarding efficacy of more caudal stimulation, whereas large lesions in the caudal MFB generally reduced the rewarding efficacy of LH stimulation by 35-60%. Similar reductions were produced by knife cuts in the caudal MFB. These results appear to be inconsistent with the hypothesis that the reward fibers consist either of descending or ascending fibers coursing in or near the MFB. It is suggested that the reward fibers are collaterals from neurons with both their somata and their behaviorally significant terminals located primarily in the midbrain.

Methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii: an unexpected difference in epidemiologic behavior.

BACKGROUND: The Dutch guideline on hospital policy for the prevention of nosocomial spread of methicillin-resistant Staphylococcus aureus (MRSA) states that patients transferred from hospitals abroad must be placed in strict isolation immediately on admission to a hospital in the Netherlands. Three patients colonized with both MRSA and a multiresistant Acinetobacter were transferred from hospitals in Mediterranean countries to 3 different hospitals in the Netherlands. Despite isolation precautions, Acinetobacter spread in 2 of the 3 hospitals, whereas nosocomial spread of MRSA did not occur. METHODS: For outbreak analysis, the Acinetobacter isolates, identified as Acinetobacter baumannii by the use of amplified ribosomal DNA restriction analysis, were comparatively typed by 4 methods. Comparison of isolation measures in the hospitals was performed retrospectively. RESULTS: In the 2 hospitals in which nosocomial spread of Acinetobacter occurred, most of the epidemiologically related isolates were indistinguishable from the index strains. In these 2 hospitals, isolation measures were in concordance with those recommended for the prevention of contact transmission. The precautions of the hospital in which no outbreak occurred included the prevention of airborne transmission. CONCLUSIONS: Precautions recommended for multiresistant gram-negative organisms are insufficient for the prevention of nosocomial spread of multiresistant Acinetobacter. The airborne mode of spread of acinetobacters should be taken into account, and guidelines should be revised accordingly.

Conformation prediction and spectral studies on adrenodoxin. The accessibility of the tyrosine residue at position 82 in the polypeptide.

The nature and accessibility of Tyr 82 were studied by fluorimetry and ultraviolet spectroscopy. A strongly emitting residue was indicated by the fluorescence yield measurement. Lowering of fluorescence yield in the presence of guanidine may be suggestive of the location of the tyrosine residue in a helical environment. The addition of external quenchers, Cs+, I-, and phosphate, to adrenodoxin lowered its fluorescence intensity showing the accessibility of Tyr 82. For solvent perturbation studies using ethylene glycol and polyethylene glycol as perturbants, spectral changes were induced in adrenodoxin which gave rise to difference spectra attributable to the tyrosine residue. In addition, the spectrophotometric titration of tyrosine in adrenodoxin showed a normal titration curve with an estimated pK of 10.4. These results can be explained in terms of an accessible tyrosine residue that is partially blocked from solute and solvent perturbation. The secondary structure of adrenodoxin was studied by the method of Chou and Fasman (Chou, P. Y., and Fasman, G. D. (1978) Annu. Rev. Biochem. 47, 251-276) for the empirical predictions of protein conformations. The prediction shows a protein with moderately high amount of ordered structures (25% alpha-helix and 37% beta-sheet) and the tyrosine residue at position 82 in a helical environment.

Improved bacteriological surveillance of haemodialysis fluids: a comparison between Tryptic soy agar and Reasoner's 2A media.

BACKGROUND: Accurate microbiological surveillance in haemodialysis centres is important as end-stage renal patients can suffer from pyrogenic reactions due to bacterial contamination of dialysis fluids. To evaluate the microbiological quality of haemodialysis fluids, special nutrient-poor culture techniques are necessary. Although the Association for the Advancement of Medical Instrumentation (AAMI) recommends Tryptic soy agar (TSA) as the standard agar, several studies have resulted in a general preference for Reasoner's 2A (R2A) agar, as it appeared to be more sensitive in demonstrating contamination of typical haemodialysis associated bacteria. In the Netherlands TSA is still used for culturing dialysate, while dialysis water is cultured on R2A. Therefore, the aims of our study were to evaluate bacterial yields of dialysis fluids on both media, and to qualify their use in routine microbiological monitoring within our haemodialysis centre. METHODS: Between April 1995 and March 1996, 229 samples of pre-treated and final purified dialysis water, and samples of dialysates were collected. The specimens were aseptically taken from the tap, various points of the reverse osmosis (RO) water-treatment system, and the effluent tubes of 32 bicarbonate haemodialysis machines. Samples of 0.1 ml were inoculated in duplicate on spread plates with TSA and R2A agars. After 10 days of incubation at 25+/-2 degrees C, the numbers of colonies were quantified. The ranges of spread were taken 0-100 and 0-200 colony-forming units per milliliter (c.f.u./ml). RESULTS: The R2A agar had significantly higher colony counts than TSA agar for both dialysis water and dialysates. Considering 100 c.f.u./ml as the upper allowable bacterial limit for all dialysis fluids, microbiological non-compliance (bacterial growth) would be missed in 16% when using only TSA media (TSA < or =100 c.f.u./ml and R2A >100 c.f.u./ml), while this was 3% when using only R2A (TSA >100 c.f.u./ml and R2A < or =100 c.f.u./ml, P<0.0001). Considering 200 c.f.u./ml as the upper limit, non-compliance would have been missed in 10% when using only TSA (TSA < or =200 c.f.u./ml and R2A >200 c.f.u./ml), and 2% when using R2A (TSA > 200 c.f.u./ml and R2A < or =200 c.f.u./ml, P = 0.0011). CONCLUSIONS: Microbiological surveillance of haemodialysis fluids, including pre-treated dialysis water samples collected from RO treatment systems, can be performed more precisely with R2A media than TSA, when incubated at 25+/-2 degrees C for 10 days.