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Biomedical subjects

A A Weiss

Publications and source records attributed to A A Weiss.

14 recordsLinked to original sources
PubMed1992

Enzymatic activity of adenylate cyclase toxin from Bordetella pertussis is not required for hemolysis.

Adenylate cyclase (AC) toxin from Bordetella pertussis enters cells to cause supraphysiologic increases in cAMP. AC toxin is also hemolytic. Substitution of Lys-58 with a methionine residue by site-directed mutagenesis of the structural gene for AC toxin, cyaA, and introduction of this mutation onto the B. pertussis chromosome results in an organism that synthesizes an enzyme-deficient AC toxin molecule. This mutant toxin molecule exhibits 1000-fold reduction in enzymatic activity relative to wild-type and has no toxin activity in J774 cells. The enzyme-deficient toxin molecule is not, however, impaired in its ability to lyse sheep red blood cells. In order to ascertain the importance of these two separate activities of AC toxin in vivo the enzyme-deficient organisms were used to infect infant mice. The hemolytic, enzyme-deficient mutant organisms are reduced in virulence relative to wild-type organisms after intranasal challenge indicating that, although the enzymatic activity of AC toxin does not contribute to hemolysis, it is this property of the toxin which is important for virulence of B. pertussis.

Adenylate Cyclase Toxin↗
PubMed1992

Index finger pollicization for congenital aplasia or hypoplasia of the thumb.

Sensation, strength, dexterity, length, and range of motion were evaluated after index finger pollicization in 10 patients (14 hands). Diagnoses included congenital absence of the thumb (10 hands) and hypoplasia (4 hands). Average age at operation was 7 years, and follow-up averaged 9 years. Patients with unilateral pollicization averaged 67% grip strength, 60% lateral pinch, 56% palmar pinch, and 39% three-point pinch as compared with the normal contralateral hand. Manual dexterity averaged 70% efficiency as compared with normal standards defined according to age and sex. However, 55% of the patients, when stressed, used side-to-side pinch. It was noted that in those patients who used side-to-side pinch performance averaged 54% of normal standards, compared with 93% in patients who used tip-to-tip pinch for prehension.

Child↗
PubMed1992

Bipolar latissimus dorsi transposition and functional neuromuscular stimulation to restore elbow flexion in an individual with C4 quadriplegia and C5 denervation.

A bipolar latissimus dorsi transposition was performed on a 17-year-old male patient with a C4 spinal cord injury and complete peripheral denervation at C5. Electrical stimulation of the paralyzed but excitable latissimus dorsi provided elbow flexion that could not be achieved with the paralyzed and denervated elbow flexors. The muscle was attached from the coracoid to the ulna allowing the elbow to be flexed with the forearm and wrist maintained in the neutral position. Following a 6-week immobilization period, the transposed muscle was exercised daily with intramuscular stimulation to increase both strength and endurance. By the fourth month after surgery, the subject could control elbow flexion proportionally with contralateral shoulder elevation using a shoulder position transducer. Functionally, the subject was able to use the neuroprosthetic system to bring his hand to his mouth and feed himself with the aid of a universal cuff and a support to stabilize the shoulder.

Adolescent↗
PubMed1979

Transposon A-generated mutations in the mercuric resistance genes of plasmid R100-1.

A series of 23 transposon 801(Tn801)-induced mutations of plasmid R100-1 from mercuric salts resistance to sensitivity was studied. Although Tn801 transposed frequently into the mer region of the plasmid, fine structural analysis showed that the site of insertion within mer varied. About one-half of the Tn801 insertion events also caused a deletion of greater than 1 megadalton. Genetic and restriction endonuclease EcoRI and BamHI analysis of the mutant plasmid deoxyribonucleic acid elucidated the organization of the mer operon and suggested the existence of a trans-acting regulatory factor governing resistance to mercuric salts. Tn801 insertions leading to mercuric sensitivity occurred in the restriction endonuclease fragments EcoRI-H and EcoRI-I. Regulatory mutations leading to a 50-fold-reduced synthesis of mercuric reductase enzyme occurred in two complementation classes thought to represent the gene for a trans-acting inducer molecule and a cis-acting operator-promoter sequence. Mutations leading to total loss of the enzyme mercuric reductase occurred on both the EcoRI-H and EcoRI-I fragments, showing that the structural gene for this enzyme (merA) bridges the EcoRI cleavage site separating the segments. Hypersensitivity to mercuric salts resulted when Tn801 insertion occurred in the reductase gene in the operatordistal portion of the operon. Hypersensitive cells inducibly bound three to five times more Hg2+ at low concentrations than did sensitive (plasmidless) cells. This finding led to the proposal that another gene (merT) controls uptake of Hg2+ by the cells. Transcription of the operon was deduced to start in the EcoRI-H fragment and to move into the EcoRI-I fragment of the plasmid genome.

DNA Transposable Elements↗
PubMed1978

Cation transport alteration associated with plasmid-determined resistance to cadmium in Staphylococcus aureus.

Plasmid-determined resistance to cadmium has only been found with plasmids from Staphylococcus aureus. Resistance to cadmium was associated with a lower accumulation of Cd(2+) ions by the plasmid-bearing resistant cells. Cadmium accumulation by susceptible cells was energy dependent and had those characteristics usually associated with a transmembrane active transport system. There was a specific interrelationship between cadmium accumulation and manganese accumulation and retention. Cd(2+) inhibited the uptake of Mn(2+) and accelerated the loss of intracellular Mn(2+) by the susceptible cells, but was without effect on Mn(2+) transport in resistant S. aureus cells. Under similar conditions, there was no differential effect of Cd(2+) on Mg(2+), Zn(2+), Co(2+), Ni(2+), or Rb(+) accumulation or exchange between the susceptible and the resistant strains.

Biological Transport↗
PubMed1977

Mercury and organomercurial resistances determined by plasmids in Pseudomonas.

Mercury and organomercurial resistance determined by genes on ten Pseudomonas aeruginosa plasmids and one Pseudomonas putida plasmid have been studied with regard to the range of substrates and the range of inducers. The plasmidless strains were sensitive to growth inhibition by Hg(2+) and did not volatilize Hg(0) from Hg(2+). A strain with plasmid RP1 (which does not confer resistance to Hg(2+)) similarly did not volatilize mercury. All 10 plasmids determine mercury resistance by way of an inducible enzyme system. Hg(2+) was reduced to Hg(0), which is insoluble in water and rapidly volatilizes from the growth medium. Plasmids pMG1, pMG2, R26, R933, R93-1, and pVS1 in P. aeruginosa and MER in P. putida conferred resistance to and the ability to volatilize mercury from Hg(2+), but strains with these plasmids were sensitive to and could not volatilize mercury from the organomercurials methylmercury, ethylmercury, phenylmercury, and thimerosal. These plasmids, in addition, conferred resistance to the organomercurials merbromin, p-hydroxymercuribenzoate, and fluorescein mercuric acetate. The other plasmids, FP2, R38, R3108, and pVS2, determined resistance to and decomposition of a range of organomercurials, including methylmercury, ethylmercury, phenylmercury, and thimerosal. These plasmids also conferred resistance to the organomercurials merbromin, p-hydroxymercuribenzoate, and fluorescein mercuric acetate by a mechanism not involving degradation. In all cases, organomercurial decomposition and mercury volatilization were induced by exposure to Hg(2+) or organomercurials. The plasmids differed in the relative efficacy of inducers. Hg(2+) resistance with strains that are organomercurial sensitive appeared to be induced preferentially by Hg(2+) and only poorly by organomercurials to which the cells are sensitive. However, the organomercurials p-hydroxymercuribenzoate, merbromin, and fluorescein mercuric acetate were strong gratuitous inducers but not substrates for the Hg(2+) volatilization system. With strains resistant to phenylmercury and thimerosal, these organomercurials were both inducers and substrates.

Chemical Phenomena↗
PubMed1977

Mercury and organomercurial resistances determined by plasmids in Staphylococcus aureus.

Penicillinase plasmids of Staphylococcus aureus often contain genes conferring resistance to inorganic mercury (Hg(2+)) and the organomercurial phenylmercury acetate. The mechanism of resistance was found to be the enzymatic hydrolysis of the organomercurial phenylmercury to benzene plus inorganic ionic mercury, which was then enzymatically reduced to metallic mercury (Hg(0)). The Hg(0) was rapidly volatilized from the medium into the atmosphere. After the mercurial was degraded and the mercury was volatilized, the resistant cells were able to grow. These plasmids also conferred the ability to volatilize mercury from thimerosal, although the plasmid-bearing strains were equally as thimerosal sensitive as the S. aureus without plasmids. None of the plasmids conferred the ability to volatilize mercury from several other organomercurials, however: methylmercury, ethylmercury, p-hydroxymercuribenzoate, merbromin, and fluorescein mercuric acetate. (Organomercurial resistance-conferring plasmids of Escherichia coli and Pseudomonas aeruginosa that we have been studying confer the ability to degrade two or three of these organomercurials.) Although mercury was not volatilized from p-hydroxymercuribenzoate or fluorescein mercuric acetate, the plasmid-bearing strains were resistant to these organomercurials. The ability to volatilize mercury from Hg(2+) and phenylmercury was inducible. The range of inducers included Hg(2+), phenylmercury, and several organomercurials that were not substrates for the degradation system. Mercury-sensitive mutants have been isolated from the parental plasmids pI258 and pII147. Thirty-one such mercury-sensitive strains fall into three classes: (i) mercury-sensitive strains totally devoid of the phenylmercury hydrolase and Hg(2+) reductase activities; (ii) mutants with normal hydrolase levels and no detectable reductase; and (iii) mutants with essentially normal hydrolase levels and low and variable (5 to 25%) levels of reductase activities. The mercury-sensitive strains were also sensitive to phenylmercury, including those with the potential for hydrolase activity.

Drug Resistance, Microbial↗
PubMed1976

Evaluation of ego strength based on certain Rorschach variables.

Despite the importance of the assessment of ego strength for appropriate assignment of clients for psychotherapy and/or rehabilitation, existing techniques have not fulfilled expectations. A method for assessing ego strength through the Rorschach Test independent of clinical criterion is proposed. In addition to certain variables of Klopfer's RPRS (M+, FM+, FC+ plus CF+), sharply preceived space responses are included. They constitute a highly intercorrelated global measure of ego strength and are also highly correlated to a relatively independent Rorschach variable of global ego efficiency, i.e. integrated whole responses. In accordance with prediction, non-controlled color responses as well as accuracy of form perception did not correlate in a non-clinical sample with either measure of ego strength.

Adult↗
PubMed1975

Directionality in four Bender-Gestalt figures: III.

Two predictions, viz., that for Austrian non-clinical school children whose left-right reading-writing habits parallel an assumed innate left-right drawing tendency, a clear preference for left-right execution of 4 Bender-Gestalt figures (Nos. 1, 2, 3, 6) would be attained at an earlier age and no plateau would be observed in contrast to Israeli non-clinical school children whose right-left reading-writing habits are in a direction opposite to the assumed innate drawing tendency, were confirmed at significant levels of confidence. In a sub-sample of the Austrian population investigated fathers' educational/occupational level as well as the child's position in his sibship as measures of attention and stimulation in the home do not appear to have any significant influence on preference for direction of drawing.

Adolescent↗