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J Kaplan

Publications and source records attributed to J Kaplan.

At least 235 records · Page 13Linked to original sources
PubMed1992

Phenotype-genotype correlations in X linked retinitis pigmentosa.

Retinitis pigmentosa (RP) represents a group of clinically heterogeneous retinal degenerations in which all modes of inheritance have been described. We have previously found two different clinical profiles in X linked RP as a function of age and mode of onset. The first clinical form has very early onset with severe myopia. The second form starts later with night blindness with mild myopia or none. At least two genes have been identified in X linked forms, namely RP2 (linked to DXS7, DXS255, and DXS14) and RP3 (linked to DXS84 and OTC) on the short arm of the X chromosome. In order to contribute to phenotype-genotype correlations in X linked RP, we tested the hypothesis that the two clinical profiles could be accounted for by the two different gene loci. The present study provides evidence for linkage of the clinical form with early myopia as the onset symptom with the RP2 gene (pairwise linkage to DXS255: Z = 3.13 at theta = 0), while the clinical form with later night blindness as the onset symptom is linked to the RP3 gene (pairwise linkage to OTC: Z = 4.16 at theta = 0).

Female↗
PubMed1992

Mapping the eye diseases.

In this review the authors first give an overview of the general strategies of mapping which differ whether the biochemical (molecular) defect of the disease is known or not. The main problems besides mapping are concerned for the first category with the correlation between mutation and phenotype and for the second, with heterogeneity, genetic vs phenotypic. Finally, tables are displayed of eye diseases or diseases with eye involvement (metabolic or not) which have been currently mapped, as well as candidate genes actually or putatively involved in visual transduction.

Chromosome Mapping↗
PubMed1992

Confirmation and refinement of the genetic localization of the Coffin-Lowry syndrome locus in Xp22.1-p22.2.

The Coffin-Lowry syndrome (CLS) is an X-linked inherited disease of unknown pathogenesis characterized by severe mental retardation, typical facial and digital anomalies, and progressive skeletal deformations. Our previous linkage analysis, based on four pedigrees with the disease, suggested a localization for the CLS locus in Xp22.1-p22.2, with the most likely position between the marker loci DXS41 and DXS43. We have now extended the study to 16 families by using seven RFLP marker loci spanning the Xp22.1-p22.2 region. Linkage has been established with five markers from this part of the X chromosome: DXS274 (lod score [Z] (theta) = 3.53 at theta = .08), DXS43 (Z(theta) = 3.16 at theta = .08), DXS197 (Z(theta) = 3.03 at theta = .05), DXS41 (Z(theta) = 2.89 at theta = .08), and DXS207 (Z(theta) = 2.73 at theta = .13). A multipoint linkage analysis further placed, with a maximum multipoint Z of 7.30, the mutation-causing CLS within a 7-cM interval defined by the cluster of tightly linked markers (DXS207-DXS43-DXS197) on the distal side and by DXS274 on the proximal side. Thus, these further linkage data confirm and refine the map location for the gene responsible for CLS in Xp22.1-p22.2. As no linkage heterogeneity was detected, this validates the use of the Xp22.1-p22.2 markers for carrier detection and prenatal diagnosis in CLS families.

Abnormalities, Multiple↗
PubMed1992

Indeterminate HTLV serologic results in U.S. blood donors: are they due to HTLV-I or HTLV-II?

Current screening tests to detect human T-lymphotropic virus type I (HTLV-I) in volunteer blood donors commonly yield indeterminate HTLV serologic results (mostly isolated gag reactors). To assess the significance of indeterminate HTLV serologic results in U.S. blood donors, we compared 56 persons who had such serologic patterns with 30 HTLV seropositive blood donors and with HTLV seronegative controls. Polymerase chain reaction assays showed that none of the 56 individuals with indeterminate HTLV serologic results were infected with HTLV-I or HTLV-II, while all 30 HTLV seropositive blood donors were infected with either HTLV-I (in 15) or HTLV-II (in the other 15). The seroindeterminate blood donors were also different from the HTLV seropositive blood donors and more like HTLV seronegative controls in their demographic characteristics and the presence of HTLV risk factors. These results are evidence that volunteer blood donors with isolated and persistent gag seroreactivity in the United States are unlikely to be infected with HTLV-I or HTLV-II.

Adolescent↗
PubMed1991

Iron absorption in hypotransferrinemic mice.

We used a unique animal model, the hypotransferrinemic (Htx) mouse, to examine the role of transferrin (Tf) in gastrointestinal iron uptake. Despite the absence of Tf, Htx animals hyperabsorb iron. Transfusion of red blood cells sufficient to normalize the hematocrit and reticulocyte count resulted in a return of iron absorption to normal values. These studies indicate that Tf does not play an obligate role in iron absorption, either as a carrier or as a humoral signal regulating absorption. Transfer of plasma or whole blood from Htx mice or from other animal models of iron hyperabsorption to normal mice did not cause an increase in iron absorption in recipient animals. Using the plasma or blood transfer approach, we have been unable to detect a humoral regulator of gastrointestinal iron absorption.

Animals↗
PubMed1991

Regulation of the transferrin-independent iron transport system in cultured cells.

Mammalian cells accumulate iron via the binding of transferrin to high affinity surface receptors, or through a transferrin-independent pathway which involves the uptake of iron-organic anion chelates by a membrane-based transport system. Previously we determined that the transferrin-independent transport system was present on a wide variety of cultured cells (Sturrock, A., Alexander, J., Lamb, J., Craven, C. M., and Kaplan, J. (1990) J. Biol. Chem. 265, 3139-3145). In this communication we demonstrate that the transferrin-independent iron uptake system is regulated differently than the transferrin-mediated pathway. The activity of the transferrin-independent system was unaffected by changes in cellular growth rate, induction of DNA synthesis and cell division, or depletion of cellular iron. Exposure of cells to ferric or ferrous iron, however, resulted in a time-dependent increase in transport activity, due to a change in Vmax with no change in Km. Increased transport activity was seen in a variety of cultured cell types, occurred in the presence of cycloheximide, and persisted for hours after removal of iron. The ability of other transition metals to induce changes in transport, or to compete with iron for accumulation by the transferrin-independent uptake system, was critically dependent on the composition of the media in which the cells were incubated. Metals such as Cu2+ or Zn2+, but not Cd2+ or Mn2+, when dissolved in a balanced salt solution buffered with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, induced changes in the transferrin-independent iron transport system. The same metals which induced changes in transport were ineffective in media containing amino acids, ascorbate, or N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine. The Vmax of the transferrin-independent iron transport system was also elevated by increases in intracellular Ca2+. The effect of iron on transport activity, however, did not result from an iron-induced release of intracellular Ca2+. These results suggest a novel form of regulation in which the presence of extracellular iron induces the appearance of previously cryptic transporters and thus accelerates the clearance of potentially toxic molecules.

Biological Transport↗
PubMed1991

First-trimester prenatal diagnosis in quintuplets: a practical approach using step-by-step embryo reduction.

A multiple pregnancy of high rank may occur in a couple at risk for a Mendelian disorder. Prenatal diagnosis is hampered by the difficulty of (1) obtaining chorionic villi from each zygote and (2) unequivocally relating each sample to the corresponding embryo. The calculation of the genetic risk according to the number of zygotes led us to propose a diagnostic strategy based on embryo reduction, a technique initially designed to improve the perinatal outcome of multiple pregnancies with normal embryos. We report a case in which this approach allowed rational use of first-trimester chorionic villus sampling in a quintuplet pregnancy at risk for non-ketotic hyperglycinaemia, resulting in the selective birth of unaffected twins.

Abortion, Therapeutic↗
PubMed1991

Sleep and breathing in patients with the Prader-Willi syndrome.

The Prader-Willi syndrome is characterized by infantile hypotonia, early childhood obesity, mental deficiency, short stature, small hands and feet, and hypogonadism. Many patients also have hypersomnolence, experience daytime hypoventilation, and subsequently die prematurely of cardiorespiratory failure. Hypersomnolence and daytime hypoventilation are also common occurrences in the sleep apnea syndrome. For a better understanding of the relationship of sleep to the features of the Prader-Willi syndrome, we retrospectively reviewed five patients (two adults, one adolescent, and two children) with this syndrome who underwent polysomnography. All patients were obese; they had hypersomnolence and daytime hypoxemia, and they nored. In all patients, the apnea plus hypopnea index was less than 10 episodes per hour of sleep. During rapid eye movement sleep, nonapneic reductions in oxyhemoglobin saturation were detected in one adult and in one child. Despite the presence of morbid obesity and a history of snoring, patients with Prader-Willi syndrome seem to have only mild sleep-disordered breathing.

Academic Medical Centers↗
PubMed1991

Sequential dacarbazine/cisplatin and interleukin-2 in metastatic melanoma: immunological effects of therapy.

Thirteen previously untreated patients with metastatic melanoma entered into a phase II chemo-immunotherapy trial were monitored immunologically during treatment. Treatment consisted of dacarbazine (DTIC) 750 mg/m2 and cisplatin 100 mg/m2 on day 1 followed by interleukin-2 (IL-2) 4 x 10(6) U/m2 by daily intravenous bolus on days 12-16 and 19-23. Cycles were repeated every 28 days. On days 1 (pretreatment), 12, 16, and 23 of each cycle, lymphokine-activated killer (LAK) cell and natural killer cell activity as well as total lymphocyte count and CD3, CD4, CD8, and CD56 lymphocyte subsets were analyzed. Despite pretreatment with full-dose cytotoxic chemotherapy, all patients were able to respond immunologically to IL-2. Spontaneous LAK cell activity was generated by the end of each course of IL-2 administration and persisted for at least 5 days thereafter. Lymphocytosis was maximum at 5 days after IL-2 administration and included increased numbers of all measured lymphocyte subsets. IL-2 administration caused a relative increase in CD56+ cells and a relative decrease in CD3+ cells. There was a direct correlation between the increase in LAK cell activity and the increase in CD56+ lymphocytes. Antitumor responses occurred in five patients but these responses did not correlate with any of the measured changes in LAK activity or lymphocyte subsets. DTIC and cisplatin administered in this schedule does not abrogate the immunological effects of IL-2.

Adolescent↗
PubMed1991

Contribution to carrier detection and genetic counselling in X linked retinoschisis.

X linked retinoschisis (RS) is a vitreoretinal disease resulting from microcystic degeneration of the macula associated with peripheral lesions. The disease gene has already been assigned to the distal short arm of the X chromosome (Xp22.2) by linkage studies. In order to contribute both to a better localisation of the RS locus and to genetic counselling in RS families, we have carried out a clinical and genetic analysis in seven pedigrees. We show, first, that in contrast with previous reports, heterozygote carriers frequently express the disease, and display peripheral retinal alterations similar to those found in affected males. Second, while distal markers DXS16, DXS207, and DXS43 are closely linked to the disease locus, a high level of recombination events was found with centromeric markers, namely DXS274, DXS41, and DXS164. These findings must be taken into account for both carrier detection and prenatal diagnosis in X linked RS.

Female↗
PubMed1991

Goiter and hypothyroidism during re-treatment with amiodarone in a patient who previously experienced amiodarone-induced thyrotoxicosis.

A 55-year-old woman who had been receiving treatment with amiodarone for recurrent supraventricular tachyarrhythmias became thyrotoxic after 30 months of treatment. The thyroid gland was not enlarged or tender. Amiodarone was discontinued, and thyrotoxicosis gradually abated. A thyroid scan performed at that time revealed a gland of normal size and texture. Six months later, amiodarone treatment was reinstated due to life-threatening tachyarrhythmia; however, the patient remained euthyroid. Three years later, multinodular goiter began to develop, and 5 years after that, the patient became hypothyroid. Tests for thyroid autoantibodies, as well as inhibitory and stimulatory antibodies, were negative, and fine needle aspiration biopsy revealed an adenomatous goiter. Treatment with amiodarone was continued; however, therapy with L-thyroxin was initiated, followed by a complete regression of the goiter. The patient has since required a maintenance dose of L-thyroxin. The possible mechanisms by which iodine-containing drugs induce thyroid disfunction are reviewed, suggesting this case was caused by an alteration in the sensitivity of the intrinsic autoregulation of the thyroid gland to iodine.

Amiodarone↗
PubMed1990

The rate of internalization of different receptor-ligand complexes in alveolar macrophages is receptor-specific.

To probe the mechanisms of endocytosis in alveolar macrophages, we examined the internalization rates of three different receptors. Initial rates of internalization for mannosylated BSA, diferric transferrin and alpha-macroglobulin-proteinase complexes were all different. Although the absolute rates of internalization varied depending on the cell preparation, transferrin was internalized at 10-20% and alpha-macroglobulin-proteinase complex at 40-60% of the rate of manosylated-BSA. Incubation of cells with transferrin did not affect the rate of internalization of mannosylated BSA or alpha-macroglobulin-proteinase complexes, and the rates of internalization were independent of receptor occupancy. These different internalization rates could not be ascribed to different rates of diacytosis. Altering the distribution of unoccupied surface receptors by either trypsin treatment of cells at 0 degree C or exposure to hyperosmotic solutions resulted in the absolute internalization rates being affected by the experimental condition, but the hierarchy in receptor internalization rates was maintained. The fact that a variety of conditions affect receptor internalization rates to the same degree implies the existence of co-ordinate regulation at a single rate-limiting step. Based on these results, we suggest that differences in internalization rate reflect the ability of ligand-receptor complexes to be captured by coated pits.

Animals↗
PubMed1990

[Cystic fibrosis: a gene at the end of the road].

The authors first give an account of the work undertaken jointly by two Canadian and one American groups, which lead to the cloning and identification of the cystic fibrosis gene. To achieve this aim, it was necessary to clone a large region amounting to 500 kb, using chromosome walking and jumping. The gene was located from a cross-hybridization signal with two probes from the cloned region and bovine cDNA. The CF gene is made of 24 exons giving a messenger of 6,500 nucleotides and a protein of about 1,500 aminoacids. The protein structure has been deduced from its composition in aminoacids. However, the localization of the protein in the cell and its true function remain an open question. At the same time workers from those groups identified the prevalent mutation in CF. These outstanding achievements will help unravelling the physiopathology of the disease. They increase the possibilities of prevention, but it is fanciful to think that they can lead to its eradication.

Chromosome Mapping↗
PubMed1990

Characterization of a transferrin-independent uptake system for iron in HeLa cells.

HeLa cells incubated in serum-free medium accumulated 59Fe ("non-transferrin iron") when incubated with either 59Fe-citrate, 59Fe-nitrilotriacetate, or 59Fe dissolved in Tricine ascorbate. Accumulation of iron was time-, concentration-, and Ca2+-dependent and was saturable. Uptake of non-transferrin (non-Tf) iron was transferrin-independent because of the fact that uptake occurred at pH 5.5, a pH at which transferrin binds iron poorly and at which transferrin is not internalized by cells. Uptake of non-Tf iron was less affected than uptake of transferrin iron by 1) exposure of cells to trypsin, a maneuver that cleaves Tf receptors, or 2) incubation of cells with phenylarsine oxide, an agent that inhibits both fluid- and receptor-mediated internalization. After exposure of cells to non-Tf iron at 37 degrees C, most of the cell-associated radioactivity was recovered in heme and ferritin, demonstrating that iron gained access to intracellular compartments and was not simply adsorbed to the cell surface. Uptake of non-Tf iron could be partially blocked by Cu2+ in a dose-dependent manner, while the accumulation of transferrin-bound iron was unaffected by Cu2+. Other transition metals, such as Zn2+, Cd2+, and Mn2+ were able to inhibit the uptake of non-Tf iron to different degrees. The accumulation of 109Cd was inhibited by incubation of cells with non-Tf iron, Cu2+, or Mn2+. The extent of inhibition was concentration- and metal-dependent. A number of cultured cell lines including HeLa, human skin fibroblasts, and Chinese hamster ovary cells demonstrated uptake of non-Tf iron and 109Cd. Additionally, an endosome acidification mutant of Chinese hamster ovary cells, which exhibited an increase in non-Tf iron uptake, also exhibited an increase in the uptake of Cd2+. These observations suggest that the characteristics of the non-Tf iron transport system in HeLa cells are similar if not identical to those reported for perfused rat liver (Wright, T. L., Brissot, P., Ma, W.-L., and Weisiger, P. A. (1986) J. Biol. Chem. 261, 10909-10914) and suggest the existence of a family of transition metal transport systems, each with a different metal specificity.

Arsenicals↗