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Biomedical subjects

I Spector

Publications and source records attributed to I Spector.

At least 37 records · Page 2Linked to original sources
PubMed1988

Client attributions for sexual dysfunction.

This investigation examined attributions for sexual dysfunctions made by 63 individuals and 21 of their partners who presented at a sex therapy service for the following problems: erectile dysfunction, premature ejaculation, and female orgasmic dysfunctions. All participants completed measures of marital adjustment, locus of control, depression and a questionnaire which assessed: attributions of responsibility for the sexual problem, perceived control over sexual functioning, distress, effort made to improve the sexual relationship, and expectations about the efficacy of sex therapy for the problem. Results indicate that both identified patients and their partners, regardless of the dysfunction, blamed the sexual problem on the "dysfunctional individual" rather than on the circumstances or the partner. With respect to the partners, husbands of women with orgasmic dysfunction were more likely to blame themselves than the circumstances, while the opposite was true for wives of males with erectile difficulties. Individuals experiencing the dysfunction perceived themselves and their partners as having little, but equal control over the identified patient's sexuality. Correlational analyses indicate that in identified patients, the better the quality of the marital relationship, the greater the self-blame and the lower the partner blame. Those with happy marriages also made greater efforts to improve their sexual relationship and had higher expectations of success with therapy. The implications of the results for research on the role of attributions in sexual dysfunction and for assessment of cognitive factors in sexually dysfunctional individuals and their partners is discussed.

Adult↗
PubMed1987

Malignant fibrous histiocytoma of the breast. A case report.

Primary malignant fibrous histiocytoma of the breast was diagnosed in a 45-year-old Indian woman. She presented with a large ulcerated lesion and had lung metastases. Treatment was by radiotherapy, toilet mastectomy and chemotherapy. The patient died of rapid extension of lung metastases 15 months after first being seen. Although this tumour has previously been considered to have a relatively good prognosis, this report emphasises its fully malignant metastatic potential.

Breast Neoplasms↗
PubMed1987

Acute mixed-lineage leukaemia involving myeloid and T-cell phenotypes. A case report.

Among the rare acute mixed-lineage leukaemias, a myeloid T-cell phenotype has recently been recognised. An additional case characterised by myeloid cytochemistry, development of Auer rods in culture and Tdt, WT1 and T11 phenotypes on cell-marker analysis is reported. The patient died from disseminated non-reactive tuberculosis after chemotherapy.

Adolescent↗
PubMed1987

Inhibition of actin polymerization by latrunculin A.

Latrunculin A, a toxin purified from the red sea sponge Latrunculia magnifica, was found previously to induce striking reversible changes in the morphology of mammalian cells in culture and to disrupt the organization of their microfilaments. We now provide evidence that latrunculin A affects the polymerization of pure actin in vitro in a manner consistent with the formation of a 1:1 molar complex between latrunculin A and G-actin. The equilibrium dissociation constant (Kd) for the reaction in vitro is about 0.2 microM whereas the effects of the drug on cultured cells are detectable at concentrations in the medium of 0.1-1 microM.

Actins↗
PubMed1987

A unique 8;16 translocation in two infants with poorly differentiated monoblastic leukemia.

Acute monoblastic leukemia is nonrandomly associated with abnormalities involving 11q. Two infants, one a neonate and the other 19 months of age, had the same hitherto undescribed karyotypic abnormality, t(8;16)(p11;p13), associated with acute nonlymphocytic leukemia M5a. The older child had an additional translocation, t(10;11)(q11;p15), but the chromosome arms affected were the opposite to those described in acute nonlymphocytic leukemia M5a of childhood. Therefore, it is postulated that genes involved in monocytic differentiation may be situated on 8p11 or 16p13, as well as on 11q.

Bone Marrow↗
PubMed1987

Malignant melanomas in the Eur-African-Malay population of South Africa.

Malignant melanoma is common among the whites of South Africa. In the black population, the tumor is much less frequent and occurs predominantly on the lower limb--particularly the sole of the foot. This study brings to light the anomalous situation that among the Eur-African-Malay population (those of mixed ancestry), malignant melanoma has probably the lowest incidence in the world.

Adult↗
PubMed1987

Development of sodium channel protein during chemically induced differentiation of neuroblastoma cells.

We have previously shown that the [3H]saxitoxin binding site of the sodium channel is expressed independently of the [125I]scorpion toxin binding site in chick muscle cultures and in rat brain. In the present work, we studied the development of the sodium channel protein during chemically induced differentiation of N1E-115 neuroblastoma cells, using [3H]saxitoxin binding, [125I]scorpion toxin binding, and 22Na uptake techniques. When grown in their normal culture medium, these cells are mostly undifferentiated, bind 90 +/- 10 fmol of [3H]saxitoxin/mg of protein and 112 +/- 14 fmol of [125I]scorpion toxin/mg protein, and, when stimulated with scorpion toxin and batrachotoxin, take up 70 +/- 5 nmol of 22Na/min/mg of protein. Cells treated with dimethyl sulfoxide (DMSO) or hexamethylene-bis-acetamide (HMBA) differentiate morphologically within 3 days. At this time, the [3H]saxitoxin binding, the [125I]scorpion toxin binding, and the 22Na uptake values are not very different from those of undifferentiated cells. With subsequent time in DMSO or HMBA, these values continue to increase, a result indicating that the main period of sodium channel expression occurs well after the cells have assumed the morphologically differentiated state. The data indicate that the expression of sodium channels and morphological differentiation are independently regulated neuronal properties, that the attainment of morphological differentiation is necessary but not in itself sufficient for full expression of the sodium channel proteins, and that, in contrast to the chick muscle cultures and rat brain, the [3H]saxitoxin site and [125I]scorpion toxin site appear to be coregulated in N1E-115 cells.

Acetamides↗
PubMed1986

Latrunculin inhibits the microfilament-mediated processes during fertilization, cleavage and early development in sea urchins and mice.

Latrunculin A, a marine toxin from a Red Sea sponge, is a potent inhibitor of the microfilament-mediated processes of fertilization and early development in sea urchins and in mice. Sperm from sea urchins, but not those from Limulus or mice, were affected by latrunculin, and fertilization in both sea urchins and in mice was arrested but at different stages. Sea urchin sperm treated with 2.6 microM latrunculin are unable to assemble acrosomal processes and their ability to fertilize eggs is impaired. The unwinding of the Limulus sperm acrosomal process occurs in the presence of latrunculin. Treated mouse sperm are able to fertilize mouse oocytes in vitro, suggesting that microfilaments may not be required in this mammalian sperm. In sea urchin eggs, sperm incorporation, microvillar elongation and cytokinesis are inhibited. Microtubule-mediated motility occurs normally. 20 nM latrunculin prevents the morphogenetic movements during gastrulation. It reduces the viscosity of actin gels from sea urchin egg homogenates. In unfertilized mouse oocytes, it prevents the colcemid-induced dispersion of the meiotic chromosomes; accumulations of cortical actin are noted adjacent to the scattered chromosomes. Sperm incorporation during mouse fertilization in vitro is unaffected suggesting that sperm entry may occur independent of microfilament activity in mammals. However, the apposition of the pronuclei at the center of the egg cytoplasm does not occur, providing evidence that cytoplasmic microfilaments may be required for the motions leading to pronuclear union during mouse fertilization. It inhibits the second polar body formation and cytokinesis. These results indicate that latrunculin is a potent inhibitor of microfilament-mediated processes in sperm, eggs and embryos, and that it may prove to be a powerful new drug for exploring the cellular behavior of microfilaments in the maintenance of cell shape and during motility.

Acrosome↗
PubMed1986

Measurements of calcium transients in the soma, neurite, and growth cone of single cultured neurons.

Voltage-gated changes in cytosolic free calcium ion concentration were measured in single, differentiated cells of mouse neuroblastoma clone N1E-115 using the calcium-sensitive dye arsenazo III (AIII). In cells bathed in normal medium containing 10 mM calcium, the changes in AIII absorbance during a single action potential indicated an increase of 1.4 nM in cytosolic calcium. When 10 mM tetraethylammonium (TEA) was added to the bath, the action potential became prolonged and the change in cytosolic calcium increased to 3.9 nM. Under these conditions, repetitive stimulation at 0.5 Hz or faster caused a gradual decline in the amplitude and duration of the action potential and a gradual decline of the change in cytosolic calcium associated with each action potential. The amplitude of the prolonged after-hyperpolarization (AHP) that follows the action potential was found to reflect the magnitude of the change in cytosolic calcium. An action potential elicited in the cell soma caused an increase in cytosolic calcium in the soma, neurite, and growth cone regions of a single cell, indicating that the membrane of all three regions possesses voltage-gated calcium channels. Estimation of calcium flux per unit area of membrane suggests a distinct topographical organization of calcium channels. Calcium channel densities in the growth cone and cell soma regions are similar and significantly higher than that in the neurite.

Action Potentials↗
PubMed1985

AMP: a new form of marijuana.

Marijuana soaked in formaldehyde, popularly called AMP, is an increasingly prominent abuse substance. Psychiatrists and emergency physicians should be alerted to AMP's unique symptom profile.

Adult↗
PubMed1983

Pharyngeal carriage of group A beta-haemolytic streptococci in coloured and Indian schoolchildren.

Throat swabs for group A beta-haemolytic streptococci were taken from 120 Coloured children and 126 Indian children at approximately 3-monthly intervals during 1980. The prevalence of positive throat swabs was related to crowding at home as measured by the number of people per bedroom. Coloured homes were much more crowded than Indian homes, but no statistical relationship was found between the number of persons per bedroom and the positivity rates. Both groups of children had high positivity rates in summer (24,4% and 21,3% for Coloureds and Indians respectively) but low rates in spring (4,3% and 3,4% respectively). These positivity rates do not support the provision of primary prophylaxis against acute rheumatic fever for these children.

Black or African American↗
PubMed1983

Infective endocarditis due to non-toxigenic Corynebacterium diphtheriae in a child. A case report.

A case of infective endocarditis (IE) in a 5 1/2-year-old boy in whom blood and bone marrow cultures yielded an unusual organism, a non-toxigenic strain of Corynebacterium diphtheriae, is reported. This proved fatal, and at autopsy congenital valvar aortic stenosis was found, but the vegetations occurred on an anatomically normal mitral valve. Organisms such as C. diphtheriae should not be ignored when isolated from blood cultures in suspected cases of IE.

Cardiomegaly↗
PubMed1983

Latrunculins: novel marine toxins that disrupt microfilament organization in cultured cells.

Two toxins, latrunculins A and B, which contain a new class of 16- and 14-membered marine macrolides attached to the rare 2-thiazolidinone moiety, were purified recently from the Red Sea sponge Latrunculia magnifica. The effects of these toxins on cultured mouse neuroblastoma and fibroblast cells have been evaluated. In both types of cells, submicromolar toxin concentrations rapidly induce striking changes in cell morphology that are reversible upon removal of the toxin. Immunofluorescence studies with antibodies specific for cytoskeletal proteins reveal that the toxins cause major alterations in the organization of microfilaments without obvious effects on the organization of the microtubular system.

Actins↗
PubMed1983

Protein carboxyl methylation increases in parallel with differentiation of neuroblastoma cells.

Cells of mouse neuroblastoma clone N1E-115 in the confluent phase of growth can catalyze the formation of endogenous protein carboxyl methyl esters, using a protein carboxyl methylase and membrane-bound methyl acceptor proteins. The enzyme is localized predominantly in the cytosol of the cells and has a molecular weight of about 20,000 daltons. Treatment of the cells with dimethylsulfoxide (DMSO) or hexamethylene-bisacetamide (HMBA), agents that induce morphological and electrophysiological differentiation, results in a marked increase in protein carboxyl methylase activity. Maximal levels are reached 6-7 days after exposure to the agents, a time course that closely parallels the development of electrical excitability mechanisms in these cells. Serum deprivation also causes neurite outgrowth but does not enhance electrical excitability or enzyme activity. The capacity of membrane-bound neuroblastoma protein(s) to be carboxyl methylated is increased by the differentiation procedures that have been examined. However, the increase in methyl acceptor proteins induced by DMSO or HMBA is the largest, and its time course parallels electrophysiological differentiation. In contrast, serum deprivation induced a small increase that reached maximal levels within 24 h. The data suggest that increased protein carboxyl methylation is a developmentally regulated property of neuroblastoma cells and that at least two groups of methyl acceptor proteins are induced during differentiation: a minor group related to morphological differentiation, and a major group that may be related to ionic permeability mechanisms of the excitable membrane.

Animals↗
PubMed1983

Development of sodium channels during differentiation of chick skeletal muscle in culture. II. 22Na+ uptake and electrophysiological studies.

The development of the functional properties of the sodium channel of chick skeletal muscle grown in culture was studied using 22Na uptake and electrophysiological techniques. In accord with the biochemical data in the preceding paper (Baumgold, J., J. B. Parent, and I. Spector (1983) J. Neurosci. 3: 995-1003), the functional manifestations of sodium channel expression are initiated shortly after cell fusion. At this stage, the myotubes have barely detectable sodium-dependent action potentials (Vmax = 1 to 9 V/sec) and exhibit a very small amount of batrachotoxin (BTX)-stimulated 22Na+ uptake. However, when these cultures are treated with scorpion toxin (ScTX), the amplitude and rate of rise of the sodium action potential increase dramatically (Vmax = 35 to 50 V/sec) and the (BTX)-stimulated 22Na+ uptake is much larger, suggesting that ScTX unmasks channels that are already present but nonfunctional in these immature myotubes. The two different rates of development of the biochemical properties of the sodium channel described in the preceding paper are also reflected in the two separate rates of development of its functional properties. In the absence of ScTX, the amplitude and Vmax of the action potential develop at a slow rate similar to that of the [3H]saxitoxin binding, eventually reaching a Vmax of 158 V/sec by day 10; the BTX-stimulated 22Na+ uptake also rises gradually, reaching 12 nmol of 22Na+/culture/min by day 7.5. In contrast, in the presence of ScTX, the Vmax of the Na+ action potential increases more rapidly, reaching 158 V/sec by day 5 and 220 V/sec by day 10. The BTX-stimulated 22Na+ uptake also increases more rapidly in the presence of ScTX. This rapid rate of development is very similar to that for [125I]ScTX binding. These findings and those in the preceding paper suggest the existence of two types of Na+ channels: an immature, nonfunctional channel capable of binding [125I]ScTX alone, and a mature, functional channel capable of binding both [125I]ScTX and [3H]saxitoxin. They further suggest that the insertion of the immature form of the channel protein into the cell membrane shortly after cell fusion is the first event in the expression of the sodium channel. During development, the sodium channel undergoes a structural change which renders it functional. The possibility that both the appearance of functional sodium channels during development and the rapid induction of functional channels by ScTX in immature myotubes reflect a post-translational modification or aggregation of immature nonfunctional channels is discussed.

Animals↗