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J G Kaplan

Publications and source records attributed to J G Kaplan.

At least 19 recordsLinked to original sources
PubMed1991

Bilateral burning foot pain: monitoring of pain, sensation, and autonomic function during successful treatment with sympathetic blockade.

We describe a patient with burning pain in both feet associated with local autonomic disturbances following bilateral traumatic sciatic mononeuropathies. The diagnosis of a sympathetically maintained pain was confirmed through a prompt response to sympathetic blockade. Although a mild alcohol-nutritional neuropathy was found, the clinical findings strongly suggested a diagnosis of bilateral causalgia. Clinical evaluation and quantitative sensory testing were performed prior to and after successive unilateral lumbar sympathetic nerve blocks. After unilateral blockade, bilateral improvement was recorded in measures of pain, sudomotor function, and foot temperature. Other measures of autonomic function showed variable responses to sympathetic blockade. Quantitative sensory testing revealed a dramatic alteration in the contralateral limb's thermal sense following unilateral block. This case underscores the potential for bilateral causalgia and provides additional evidence for a central mechanism operating in this disorder. The relationship between bilateral causalgia and the "burning feet syndrome" in alcoholic neuropathy is discussed.

Adult↗
PubMed1990

Polyradiculopathy in leptomeningeal metastasis: the role of EMG and late response studies.

Leptomeningeal metastasis (LM) of systemic malignancy often give rise to multifocal involvement of the central (CNS) and peripheral nervous system. Signs of CNS dysfunction such as seizures and confusion often overshadow radicular deficits. We report clinical and laboratory evaluations in 10 patients with LM who presented with isolated polyradiculopathy. Our data suggest that electromyography and late response studies are sensitive indicators of radicular dysfunction in patients with LM. These studies are helpful in the early documentation of root involvement when computerized tomography, MRI and myelography are normal.

Adult↗
PubMed1979

Extensive soft tissue calcification (calcinosis universalis) in systemic lupus erythematosus.

A 21-year-old woman with long-standing systemic lupus erythematosus developed extensive calcification of the soft tissues of the thoracic and abdominal walls and extremities early in her illness, and these calcifications gradually disappeared over the course of her disease. The extent of this calcinosis and apparent spontaneous regression are unusual events in systemic lupus erythematosus.

Adult↗
PubMed1979

Microtubules, colchicine, and lymphocyte blastogenesis.

We have studied the time course of disassembly of microtubules of resting and stimulated mouse lymphocytes caused by the drug colchicine, as well as the effect of this compound on DNA and RNA synthesis of human and mouse lymphocytes. Fine-structure studies with the electron microscope showed a great increase in number of microtubules resulting from stimulation of mouse lymphocytes by the mitogenic lectin Con A. The presence of a network of microtubules was demonstrated in resting lymphocytes by use of the technique of immunofluorescence; this technique was not effective for the study of the microtubules of stimulated lymphocytes in the blast stage. The disappearance of microtubular networks in some cells (approximately 25%) was caused by the protocol of colchicine treatment used in many laboratories (30 min at 10(6) M); a 6- to 8-h treatment was required to cause all cells to lose their microtubules. It is indicated in these findings that there is need for extreme caution in implicating microtubule disruption as the cause of certain colchicine effects, such as that on the Con A-induced inhibition of receptor-ligand migration. The addition of colchicine to stimulated cells at varying times of culture caused marked inhibition of DNA synthesis provided that sufficient time (approximately 20 h for maximum inhibition) elapsed between addition of the drug to the stimulated culture and assay of DNA synthesis. Our data on the time course of inhibition of DNA synthesis by alpha-methyl mannoside (alpha MM) and by colchicine do not exclude the possibility that the latter compound may act partially by affecting the commitment of stimulated lymphocytes to DNA synthesis but they show that it can inhibit well after commitment is complete. The later the time of assay of thymidine incorporation, the more disparate were the curves relating the effects of alpha MM and colchicine to DNA synthesis of human cells. In the case of mouse splenic lymphocytes, there was no resemblance between the time course of the alpha MM and of the colchicine effects. Synthesis of RNA after 12 h of culture of stimulated human lymphocytes was also sensitive to colchicine.

Animals↗
PubMed1978

Response of human lymphocytes to mitogen: at what stage is there a requirement for Ca2+?

In order for significant DNA synthesis to be observed in the case of human lymphocytes stimulated for 36 h in presence of phytohemagglutinin (PHA), Ca2+ must be present in the medium continuously for at least 20 h; access to Ca2+ for 10-h periods during the first 30 h was not sufficient to permit DNA synthesis to occur. Addition of the chelator EGTA from 0 to 60 h after stimulation caused severe inhibition of incorporation of labelled thymidine when this was measured after 36 to 144 h of culture. Equimolar calcium reversed the inhibition caused by EGTA. Incorporation of labelled uridine and leucine showed a temporal pattern of dependence on the presence of Ca2+ in the medium similar to that of thymidine. Ca2+ appears not to be required in the medium during the last half (i.e., 20-36 h) of the presynthetic G1 phase nor during S phase since removal of Ca2+ from the medium after 20 h did not prevent a subpopulation of lymphocytes from entering S phase 16 h later.

Calcium↗
PubMed1976

Fine structure of the URA2 locus in Saccharomyces cerevisiae. II. Meiotic and mitotic mapping studies.

The URA2 locus codes for a multifunctional enzyme complex carrying aspartate transcarbamylase (ATCase) and carbamyly phosphate synthetase (CPSase) activities. Three different types of ura2 mutants were tested in meiotic and mitotic recombination experiments: ura2A mutants devoid of ATCase activity, ura2C mutants devoid of CPSase activity and ura2B mutants devoid of both activities. All the ura2A mutations were found to be clustered at one end of the URA2 locus, called zone A, while the ura2C mutations were localized in a region at the other end, called zone C. All but two ura2B mutations (most of them suppressible) were distributed throughout zone C; the two ura2B exceptions which are small deletions, mapped in zone A. On the meiotic as well as on the mitotic map an intermediary or dead-space zone is located between zones A and C. No mutation has yet been found to map in this zone. The relative lengths of the three zones A, intermediary and C are 1 :2-3 :3-4, respectively. These data are consistent with the hypothesis that the URA2 locus consisting of at least two cistrons: C (CPSase) and A (ATCase), is transcribed into a single polycistronic message in the direction C to A. However, alternative hypotheses in reference to Peterson and MacLaughlin's observations (1973) are discussed.

Aspartate Carbamoyltransferase↗
PubMed1976

antigen-induced.

Explore the source record for details and available documents.

Antigens↗
PubMed1976

Studies of the regulation and reaction mechanism of the carbamyl phosphate synthetase and aspartate transcarbamylase of bakers' yeast.

Kinetic studies of the carbamyl phosphate synthetase activity (CPSase) of bakers' yeast revealed an absolute requirement for K+ ions ; KM values for two of the substrates, glutamine and bicarbonate, were found to be 5 X 10(-4) M and 3 X 10(-3) M respectively. CPSase activity of the purified enzyme aggregate (M.W. 800,000) was extremely sensitive to UTP with a Ki of 2.4 X 10(-4) M. The purine nucleotide intermediate, XMP, was a strong activator of CPSase, acting at a site different from the regulatory site at which UTP binds ; XMP activation diminished at high concentrations of the substrate Mg-ATP. Studies of the reaction mechanism of CPSase revealed that it involved the sequential addition of the substrates bicarbonate and Mg-ATP, liberation of ADP, addition of glutamine, binding of ATP and then release of ADP and the product carbamyl phosphate. Studies of the reaction mechanism of the aspartate transcarbamylase (ATCase) of the aggregate yielded data which were not compatible with any of the usual models ; whichever reaction mechanism is ultivately found to fit the data, it will probably prove applicable both to the ATCase of the aggregate and to the disaggregated ATCase subunit (MW 138,000).

Adenosine Triphosphate↗
PubMed1976

Persistent effects of ouabain treatment on human lymphocytes: synthesis of DNA, RNA and protein in stimulated and unstimulated cells.

Pretreatment of human lymphocytes for 2 days in 2 X 10(-6)M ouabain caused irreversible loss of their subsequent capacity to stimulate in the mixed lymphocyte reaction (MLR). Pretreatment for the same period with 10(-7)M ouabain resulted in an enhanced incorporation of thymidine into DNA of the responding cells in the MLR; this effect was also on the stimulating cells, as previously reported by Christen et al. (Cell, Immunol. 19, 137-142 (1975)). Pretreatment of stimulating lymphocytes with 10(-7)M ouabain caused a persistent but reversible inhibition of the synthesis of RNA and protein in the MLR; peak incorporation of labelled uridine or alanine reached the same level as that of the control cultures, but 24 h later. Exactly the same persistent but reversible inhibition was found in the case of DNA syntheis of cells pretreated with 10(-7)M ouabain and then stimulated by antigens (streptolysin-O and varidase) or by mitogens (phytohemagglutinin and concanavalin A); the same level of incorporation of labelled thymidine occurred but 24-48 h later than in the case of the controls. Pretreatment with the cardiotonic steroid under these conditions also resulted in a pronounced inhibition of the basal, unstimulated levels of RNA and protein synthesis in the case of both control lymphocytes and those which had been treated with mitomycin C. The effects of ouabain pretreatment on basal RNA and protein synthesis were identical for both 2 X 10(-6)M and for 10(-7)M; the effect of pretreatment of stimulating cells with these two concentrations was completely opposite: irreversible inhibition of the proliferative response of allogeneic responding cells at the former concentration and delayed activation at the latter.

Alanine↗