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Biomedical subjects

J Adler

Publications and source records attributed to J Adler.

At least 91 records · Page 5Linked to original sources
PubMed1993

A method for the enumeration of bacterial adhesion to epithelial cells using image analysis.

Computerised image analysis was utilised to enumerate the attachment of Staphylococcus epidermidis to HEp2 cell monolayers. A differential staining technique was employed such that individual staphylococcal cells stood out in sharp contrast against the uneven cell surface and granular contents of the epithelial cells. The primary image analysis operation involved subtracting an out-of-focus image from an in-focus image of the bacteria on the monolayer, thereby accentuating the bacterial image. Enumeration, using a particle counting routine, was rapid and reproducible, facilitating counting in excess of 700 bacteria per field at x 500 magnification. The computerised programme compared favourably with manual counting and would provide a rapid, objective and morphologically discriminatory method for evaluating bacterial attachment to various tissues.

Bacterial Adhesion↗
PubMed1993

Activities of a mechanosensitive ion channel in an E. coli mutant lacking the major lipoprotein.

The activity of the mechanosensitive (MS) ion channels in membrane patches, excised from E. coli spheroplasts, was analyzed using the patch-clamp technique. Outer membranes from a mutant lacking the major lipoprotein (Lpp) and its wild-type parent were examined. The MS-channel activities in the wild-type membrane rarely revealed substates at the time resolution used. These channels showed a stretch sensitivity indicated by the 1/Sp (the suction for an e-fold increase in channel open probability) of 4.9 mm Hg suction. The MS-channel activities of lpp included a prominent substrate and showed a weaker mechanosensitivity with an 1/Sp of 10.0 mm Hg. Whereas small amphipaths (chlorpromazine, trinitrophenol) or a larger amphipath (lysolecithin) all activated the MS channel in the wild-type membrane under minimal suction, only the larger lysolecithin could activate the MS channel in the lpp membranes. After lysolecithin addition, the lpp membrane became more effective in transmitting the stretch force to the MS channel, as indicated by a steepening of the Boltzmann curve. We discuss one interpretation of these results, in which the major lipoprotein services as a natural amphipath inserted in the inner monolayer and the loss of this natural amphipath makes the bilayer less able to transmit the gating force.

Animals↗
PubMed1993

Behavioral responses of Escherichia coli to changes in temperature caused by electric shock.

The behavioral response of Escherichia coli to electric shock in 10(-2) M potassium phosphate plus 10(-4) M potassium EDTA was studied. When presented with a 150-V/cm electric shock that lasted 250 ms, the bacteria at first exclusively ran, then exclusively tumbled, and finally returned to their original running and tumbling. This response is due to increased temperature caused by the electric shock, i.e., to thermotaxis, and it is mediated by the chemotaxis machinery. A more severe electric shock, 150 V/cm for 550 ms, caused cells to tumble immediately, and then they went back to their original running and tumbling. The mechanism of that response is unknown since, unlike known thermotaxis, it does not require the chemotaxis machinery.

Chemotaxis↗
PubMed1993

Adverse conditions which cause lack of flagella in Escherichia coli.

Wild-type Escherichia coli was not motile when grown in tryptone broth under the following adverse conditions: the presence of high temperature [J. Adler and B. Templeton, J. Gen. Microbiol. 46:175-184, 1967; R. B. Morrison and J. McCapra, Nature (London) 192:774-776, 1961; K. Ogiuti, Jpn. J. Exp. Med. 14:19-28, 1936], high concentrations of salts, high concentrations of carbohydrates, high concentrations of low-molecular-weight alcohols, or the pressure of gyrase inhibitors. Under all these conditions, growth was necessary for the loss of motility. This loss of motility was correlated with a reduction in the amount of cellular flagellin. We isolated and studied mutants that are resistant to suppression of motility by some of these conditions, because of the ability to synthesize flagella under these conditions. The mutations were mapped to 42 min, a region of the chromosome where many of the flagellar genes map. We also studied the effect of a preexisting gyrA mutation which allowed flagellar formation in the presence of nalidixate.

Cell Movement↗
PubMed1993

Mechanism of adverse conditions causing lack of flagella in Escherichia coli.

Escherichia coli lacks flagella when grown in tryptone broth in the presence of various adverse conditions (C. Li, C. J. Louise, W. Shi, and J. Adler, J. Bacteriol. 175:2229-2235, 1993). Now, the synthesis, rather than the degradation, of flagellin was shown to be inhibited. Studies of transcriptional fusions of flagellar operons to the lacZ gene revealed that transcription of the flagellar genes was reduced in cells grown under these adverse conditions. Increasing gene dosage of the flhD operon by a plasmid partially suppressed the nonflagellation caused by some adverse conditions. The signal which shuts off the synthesis of flagella under adverse conditions remains to be discovered. This shutting-off process does not result from catabolite repression or from signals from the chemotaxis system.

Chemotaxis↗
PubMed1993

Escherichia coli shows two types of behavioral responses to osmotic upshift.

Behavioral responses to osmotic upshift were characterized by temporal assays of free-swimming cells of Escherichia coli. Small osmotic upshifts (200 to 300 mosM) elicited tumble responses which were chemotaxis dependent, while large osmotic upshifts (400 to 500 mosM) elicited stopping followed by pseudotumbling which was chemotaxis independent.

Cell Movement↗
PubMed1993

The possible use for immunohistochemical detection of cells in S-phase labeled by bromodeoxyuridine.

Experiences with the use of bromodeoxyuridine (BrdU) as a marker of cellular division were described within this paper. BrdU is incorporated in the course of S-phase of cell cycle into the arising DNA in place of thymidine. The presence of BrdU in cell nuclei of tested tissues was detected with a monoclonal antibody and immunoperoxidase method. It was found that: 1. In adult rats a total dose of 100 mg is sufficient for labeling nuclei in most tissues, however intensity of the staining varies. The largest amount of BrdU was revealed in enterocyte nuclei. Lower level of BrdU was detected in cells in the spleen and in the interalveolar septa (probably macrophages) and the lowest one was found in the liver (hepatocytes, Kupffer, and Ito cells); with the exception of individual astrocytes no labeling was revealed in the central nervous system. 2. ED14 (14 days old) rat embryo that had been exposed to BrdU in the mother body, revealed only a weak labeling because of the uptake of BrdU in the placenta. The highest level of BrdU was observed in mesenchymal cells surrounding primitive organs. 3. Explants of the cerebral rat ED14 cortex that had been exposed to BrdU during intrauterine development, remain to be BrdU positive even after their transplantation into the recipient's brain. Different intensity of cell nuclei labeling reflects the rate of mitoses from embryonic day 12 (ED12) to ED14 when BrdU had been administered.

Animals↗
PubMed1993

Inoculation of C6 cell suspension into the brain of adult rats: immunohistochemical study.

C6 glioma cell suspension has been inoculated into the brain of adult Long Evans rats. Animals were allowed to survive 2 to 60 days and then immunohistochemical detection of S100 protein and glial fibrillary acidic protein (GFAP) in tumors was carried out on paraffin-embedded sections. In our in vivo model the maximum positivity for both S 100 protein and GFAP was observed in C6 glial cells at 10 days after implantation. At that time increased levels of S 100 protein were expressed both in central areas containing more differentiated C6 glioma cells and in host reactive astrocytes at tumor boundary. Almost no S 100 protein was found in dividing and invading, i.e. less differentiated, C6 glioma cells at tumor periphery and in perivascular spaces of adjacent blood vessels. The distribution of GFAP positive cells followed a similar pattern as that of S 100 protein containing C6 cells. GFAP expressing cells were revealed in quiescent central tumor portions which were occupied by more differentiated cells. Tumors were surrounded by strongly GFAP positive host reactive astrocytes. Later on, when signs of tumor regression appeared there was a decrease in S 100 protein and GFAP immunoreactivity of C6 glioma cells. To summarize, we developed an in vivo model for observation of cell differentiation within a growing glioma. Less differentiated and more malignant glioma cells expressed almost no S 100 protein and GFAP in contradistinction to central and more quiescent tumor portions.

Animals↗
PubMed1993

Disassembly of microtubules due to low intensity ultrasound.

HeLa and MCF cell monolayers growing on glass cover-slips were sonicated using continuous wave ultrasound at low intensity levels approaching diagnostic conditions. The disassembly of cytoplasmic microtubules immediately after sonication was demonstrated using indirect immunofluorescence. The recovery from exposure to ultrasound, i.e. the reassembly of microtubules, was observed in the cultured cells 2 h after the sonication was discontinued.

Fluorescent Antibody Technique↗
PubMed1993

[Use of cultured epidermal autotransplantation in a severely burned patient].

In the submitted paper the authors describe in detail the administration of cultivated epidermal autotransplants (CEA in a patient with severe burns (80% of the body surface). They draw attention to several problems which occurred during treatment: a) a relatively small overall increase of CEA and the long time required for their cultivation, b) the very difficult preparation of infected wound surfaces for transplantation, c) secondary healing of CEA. The solution of these problems is according to the authors optimization of the laboratory technique of CEA cultivation and substitution of the dermal component of skin.

Adolescent↗
PubMed1992

Calcium ions are involved in Escherichia coli chemotaxis.

Escherichia coli regulates intracellular free Ca2+ at about 90 nM [Gangola, P. & Rosen, B. P. (1987) J. Biol. Chem. 262, 12570-12574]. To increase intracellular free Ca2+, nitr-5/Ca2+, a "caged" Ca2+ compound, was electroporated into cells and then its affinity for Ca2+ was reduced by exposure to 370-nm light. Upon release of the Ca2+ ions, the cells tumbled. Studies on mutant strains showed that the receptor proteins (methyl-accepting chemotaxis proteins, MCPs) were not required for the Ca(2+)-induced tumbling but that CheA, CheW, and CheY proteins were required. Similar results were obtained with DM-nitrophen/Ca2+, another caged calcium compound that releases Ca2+ upon illumination at 340 nm. Diazo-2, a caged Ca2+ chelator that takes up Ca2+ upon illumination at 340 nm, was used to decrease intracellular free Ca2+, and this caused smooth swimming.

Bacterial Proteins↗
PubMed1992

Effects of sustained-release nicardipine on regression of left ventricular hypertrophy in systemic hypertension.

The effects of a sustained-release formulation of the calcium antagonist nicardipine on left ventricular (LV) mass, Doppler transmitral velocity profiles and plasma neurohumoral studies were analyzed in patients with mild to moderate systemic hypertension. A double-blind placebo control phase in 28 patients was carried out for 6 weeks with a subgroup of 13 subsequently entering an open-label long-term phase for 1 year. Nicardipine produced a significant decrease in systolic and diastolic pressure over the 6-week phase (158 +/- 15 to 142 +/- 9 mm Hg, and 100 +/- 5 to 89 +/- 9 mm Hg, respectively, both p less than 0.001). No significant differences in Doppler measures of mitral inflow or echocardiographic measures of LV function, wall thickness or mass were noted in the 6-week phase of the study. Although nicardipine increased both norepinephrine and renin values after the first dose, these levels had returned to baseline in most patients after 6 weeks. In addition, there was no evidence for stimulation of adrenomedullary activity because nicardipine had no effect on epinephrine or dopamine-B-hydroxylase levels at first dose or after 6 weeks. In the 13 patients treated for 1 year, systolic and diastolic pressure remained significantly decreased compared with pressure before therapy (135 +/- 9 vs 147 +/- 15 mm Hg, and 85 +/- 6 vs 97 +/- 9 mm Hg, both p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1992

Membrane-derived oligosaccharides (MDO's) promote closing of an E. coli porin channel.

The outer membrane of Escherichia coli is a diffusion barrier for macromolecules, but allows the passage of small hydrophilic solutes through non-specific channels, the porins. Some electrophysiological studies find reconstituted porins in a mostly open state, while those done with the patch-clamp technique performed on live cells suggest that the vast majority of the native channels are closed. We present here current measurements through porins from reconstituted outer membrane, which demonstrate that bacterial metabolites, the MDO's, which bathe the periplasmic side of the outer membrane, induce the channels to close. These findings illustrate that the degree of openness of porins can be regulated by compounds naturally found in bacteria.

Bacterial Outer Membrane Proteins↗
PubMed1992

On the identity of the major postsynaptic density protein.

Increasing evidence suggests that the postsynaptic density (PSD) plays a critical role in synaptic communication and plasticity. The major PSD protein (mPSDp), a calcium/calmodulin-dependent protein kinase, appears to be central to PSD function. The mPSDp has long been considered identical to the alpha subunit of the soluble calmodulin kinase II (alpha-CKII). However, mPSDp and alpha-CKII do differ in solubility and antigenicity, raising the possibility that the two proteins are distinct. To further define the relationship between the two proteins, we purified the mPSDp to homogeneity from adult rat cerebral cortex and compared the proteins. In contrast to alpha-CKII, the purified mPSDp was insoluble in high concentrations of salt, various detergents, chelators of divalent cations, and the strong denaturant guanidine hydrochloride. The pI value of the mPSDp was 6.2, whereas that of alpha-CKII was 6.7-7.2. The purified mPSDp bound calmodulin in the presence of Ca2+ and was autophosphorylated in a Ca2+/calmodulin-dependent manner. Polyclonal antiserum raised against mPSDp (anti-mPSDp) recognized purified mPSDp or mPSDp in synaptic membrane, indicating immunologic specificity among the synaptic proteins. Anti-mPSDp did not recognize alpha-CKII, whereas anti-alpha-CKII antibodies reacted only weakly with mPSDp, suggesting that the proteins are distinct but structurally similar. Moreover, sequence analysis of protease V8-digested polypeptides revealed that there was at least an 8-amino acid sequence, MLKVPNIS, that is not present in alpha-CKII. Finally, HPLC analysis of V8-digested fragments of mPSDp and alpha-CKII in parallel revealed dissimilar peptide patterns. Thus our observations suggest that mPSDp and alpha-CKII are similar but not identical. The unique physicochemical and structural properties of the mPSDp may provide insights into molecular mechanisms mediating synaptic plasticity.

Amino Acid Sequence↗