Diamond-Blackfan anemia: heterogenous response of hematopoietic progenitor cells in vitro to the protein product of the steel locus

Diamond-Blackfan anemia is a congenital disorder of erythropoiesis in humans, characterized by a macrocytic anemia often associated with physical anomalies. Mutations at either the W or Steel loci in the mouse also leads to a severe macrocytic anemia, as well as other developmental abnormalities. The W locus encodes the proto-oncogene c-kit, a member of the receptor tyrosine kinase family, while the Steel locus encodes a potent hematopoietic growth factor that is the ligand for c-kit. Growth of clonogenic marrow erythroid progenitor cells in vitro in the presence of the recombinant hematopoietic growth factors interleukin-3 (IL-3) and Steel was used to characterize this disease at the cellular level. Three patterns of in vitro marrow response to both recombinant IL-3 or Steel were observed among 10 Diamond-Blackfan patients: those that responded quantitatively and qualitatively almost as well as cells from normal marrow, those that responded at an intermediate level, and those that did not respond at all. These results provide evidence for cellular heterogeneity underlying the pathogenesis of this disorder and therefore raise the possibility that there may be more than one underlying molecular basis for the disease. No gross abnormalities in the structure of either the c-kit or Steel loci were observed in these patients. The normal response in culture of the progenitor cells from at least some patients to Steel with or without IL-3 raises the possibility of using this novel growth factor as a therapeutic agent in Diamond-Blackfan anemia.

Chlorobenzoate catabolic transposon Tn5271 is a composite class I element with flanking class II insertion sequences

The structure of a transposon specifying the biodegradation of chlorobenzoate contaminants is described. Tn5271 is a 17-kilobase (kb) transposon that resides in the plasmid or chromosome of Alcaligenes sp. strain BR60 and allows this organism to grow on 3- and 4-chlorobenzoate. The transposon is flanked by a directly repeated sequence of 3201 base pairs (bp), which in turn is flanked by 110-bp inverted repeats. The 3.2-kb repeated sequence, designated IS1071, exists in multiple copies in the genome of Alcaligenes sp. strain BR60 and is involved in recombination of the catabolic genes into the chromosome of this strain. Sequence analysis revealed that the inverted repeat of IS1071 and the derived amino acid sequence of the single open reading frame within IS1071 are related to the inverted repeats and transposase (TnpA) proteins of the class II (Tn3 family) transposable elements. The absence of a resolvase gene within IS1071 suggests that this element is capable of determining the first step in class II transposition only. This was confirmed by observations on the IS1071-dependent formation of stable cointegrates in a recombination-deficient Escherichia coli. These results support an evolutionary scheme in which the class II transposable elements descended from simple insertion sequences.

Growth retardation and the development of the respiratory system in fetal sheep

In an experimental model of fetal growth retardation which involves the reduction of placental mass in ewes, we have investigated the effects of intrauterine deprivation on aspects of structural development of the trachea and lungs of fetal sheep (140 days gestation). We have also measured the volume of luminal liquid aspirated from the lungs and the phospholipid content of this liquid as an index of pulmonary surfactant production. The effects of growth retardation are evident in the trachea where the structural development of the mucosal and submucosal layers has been affected. Abnormal aspects of development include the frequent lack of a ciliated border on epithelial cells in the mucosal layer and the reduction in the extent of the folds usually characteristic of this layer in near term fetal sheep. Although the fetal lungs are smaller in growth retardation (P less than 0.01) they are appropriate for fetal weight and their structural development does not appear to have been retarded. In contrast, lung liquid volume is significantly reduced in relation to lung weight in growth retarded fetuses and the concentration of phospholipids in lung liquids is also reduced (P less than 0.01).

A new frameshift beta zero-thalassemia mutation (codons 27-28 +C) found in a Chinese family

A new beta zero-thalassemia mutation, a frameshift mutation with an insertion of a single cytosine nucleotide in codon 27-28, is described. The propositus, who is compound heterozygous for this mutation and the IVSII-654 C----T beta zero-thalassemia mutation, has the phenotype of severe beta-thalassemia major.

Detection of beta-thalassemia using an artificial-restriction fragment length polymorphism generated by the polymerase chain reaction

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A randomized study to determine complications associated with duration of insertion of heparin locks

A randomized trial was conducted to assess the effect of leaving heparin locks in place longer than 72 hours. Three hundred and one patients were randomly assigned to one of two groups. Group A had the lock changed every 72 hours and Group B had the lock left in place up to 168 hours. Due to withdrawals following randomization, Group A contained 116 subjects and Group B 140 subjects. No significant differences were found between the two groups in relation to age, sex, medical condition, drug used, entries into the lock, minor complications, or incidence of phlebitis. The findings suggest that consideration could be given to extending insertion time up to 96 hours and possibly up to 118 hours.

A generalized chain binomial model with application to HIV infection

The original Reed-Frost formulation of the chain binomial model is mathematically equivalent to a stochastic model allowing a Poisson number of effective contacts in a time interval. Their formulation cannot accommodate survey data that necessarily correspond to more complex distributions of partners or contacts, or to large populations where complete random mixing is unlikely. This paper generalizes the Reed-Frost model to accommodate these situations in both the one- and two-population settings. The extension to multiple populations is also outlined. Using the model to predict HIV incidence in San Francisco's homosexual population, we show that the total number of contacts over all partners is more important than the distribution of contacts among partners in determining the number of infected.

Regulation of calcium influx across the plasma membrane of the human T-leukemic cell line, JURKAT: dependence on a rise in cytosolic free calcium can be dissociated from formation of inositol phosphates

A rise in the cytosolic free Ca2+ concentration due to both mobilization of Ca2+ from internal stores and influx of extracellular Ca2+ across the plasma membrane through 'second messenger-operated Ca2+ channels' is one of the first transmembrane signals detected following activation of CD2 or CD3 receptors on T-cells. In this study, we have further elucidated the regulation of these channels in the human T-leukemic cell line, JURKAT. Stimulation with either OKT3 or PHA induced a prompt influx of Ca2+ as assessed by MN2+ quenching of intracellular fura-2 fluorescence. When cytosolic free Ca2+ transient was partially buffered by loading the cells with BAPTA, neither agonist could induce Ca2+ entry into the cells as depicted by the lack of quenching of the fluorescence signal by Mn2+. This is in good agreement with our previous data on agonist-induced 45Ca2+ influx demonstrating that a rise in cytosolic free Ca2+ due to agonist-induced mobilization of Ca2+ from intracellular stores, could, directly or indirectly via the inositol cycle, initiate Ca2+ influx in these cells. Further support of this idea comes from the data demonstrating that agonist-induced mobilization of Ca2+ precedes the influx of Ca2+ across the plasma membrane. The present findings show that agonist-stimulation significantly increased the levels of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 after only 5 s, indicating that one or both of these substances could play a role in the regulation of Ca2+ influx. However, when agonist-induced Mn2+ influx was totally abolished, by partially buffering the cytosolic free Ca2+ rise, the formation of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 was not affected. Consequently, the dependence of an initial rise in cytosolic free Ca2+ for the subsequent regulation of Ca2+ influx across the plasma membrane, can be dissociated from the formation of both Ins(1,4,5)P3 and Ins(1,3,4,5)P4.

MR imaging of the knee: pseudotear of the lateral meniscus caused by the meniscofemoral ligament

Sagittal MR images of the knee often show a linear band of increased signal in the medial aspect of the posterior horn of the lateral meniscus that can be confused with a meniscal tear. This pseudotear is due to the meniscal insertion of the meniscofemoral ligament. To study the normal appearance of the medial aspect of the posterior horn of the lateral meniscus, we analyzed 109 MR examinations and correlated the findings with the results of arthroscopy. The meniscofemoral ligament was visualized in 54 cases (50%), and in 42 cases (39%) it caused the appearance of a pseudotear on sagittal images. The pseudotear had one of two orientations. The most common (35/42) was an oblique orientation coursing from the superior surface posteriorly and inferiorly. The other (7/42) was a more vertical orientation parallel to the base of the meniscus. Knowledge of the characteristic location and orientation of the meniscofemoral ligament should help to distinguish it from a true meniscal tear on MR images.

Fiber-optic coupling based on nonimaging expanded-beam optics

We have fabricated and experimentally tested low-cost and mass-producible multimode fiber-optic couplers and connectors based on nonimaging beam-expanding optics and Liouville's theorem. Analysis indicates that a pair coupling loss of -0.25 dB can be achieved. Experimentally, we measured insertion losses as low as -0.38 dB. The beam expanders can be mass produced owing to the use of plastic injection-molding fabrication techniques and packaged in standard connector housings. This design is compatible with the fiber geometry and can yield highly stable coupling owing to its high tolerance for misalignments.

Traumatic knee injuries: the accuracy of MRI compared with arthroscopy

Forty-three knees in 43 patients were evaluated preoperatively with magnetic resonance imaging (MRI). Both menisci and cruciate ligaments subsequently were examined directly with arthroscopy. A grading scale was used to evaluate intrameniscal signal intensity and to predict the presence of meniscal tear using MR. Compared with arthroscopy, the sensitivity, specificity and accuracy of MRI were, respectively, 100%, 88% and 93% for tears of the medial meniscus; 72.7%, 93.7% and 88.4% for tears of the lateral meniscus; 100%, 96.7% and 97.7% for tears of the anterior cruciate ligament. There were no posterior cruciate ligament tears, and none were suggested from the images. Our results show that MRI is a valuable diagnostic aid in the management of traumatic knee injury.

Fiber-optic wavelength-division multiplexing and demultiplexing using volume holographic gratings

We present theoretical and experimental results of a novel fiber-optic wavelength-division multiplexing (WDM) design employing a broadband (>150-nm) dichromated gelatin volume holographic grating operating in a reflective Littrow configuration with on-axis optics, a single lens, and one fiber array. This configuration can achieve better than -1.5-dB insertion loss and -40-dB cross talk for a 6-channel system and -2.5-dB insertion loss and -20-dB cross talk for a 12-channel system with 15-nm channel spacing. For an experimental 4-channel WDM unit we measured better than -1.5-dB insertion loss for all channels and less than -32-dB cross talk. This design can provide cost and performance benefits for local area network communication applications.

Prognostic factors and progress for ambulation in elderly patients after hip fracture

A longitudinal study of the ambulation progress was done on 102 patients in the first 9 wk after an operation for repair of hip fractures. The time taken to achieve a stable walking pattern from frame to a cane was recorded for every patient. Results showed that 82.2% of the patients were able to walk with a cane at 4 wk postoperatively. Of the remaining 17.8% of the patients, 7.7% were able to walk with a cane at 6 wk whereas 10.1% were not able to walk with a cane at 6 wk. Several factors including the age, sex, mental state, the type of operation and the preoperative ambulation level of the patients were studied to predict the ambulation progress of the patients. The most important factors affecting the ambulation progress were the age and the preoperative ambulation level of the patient. Because of the general trend in the aging of the population, an increase in the number of hip fractures is expected. The result of this study may help in predicting the prognosis and provide guidance for restoring the function of the patients.

Ultrasound guided drainage of pleural fluid

Ultrasound guided drainage has been reported as a highly successful drainage procedure. Computed tomography (CT) and fluoroscopy also have been cited as favorable imaging modalities for the treatment of pleural effusion. With its extreme sensitivity to fluid collections and rapid and accurate localization of fluid, real-time ultrasound has become the primary imaging modality for the interventional drainage of pleural fluid. This is a retrospective study of patients with radiographically suspected pleural effusion, using ultrasonic scanning for possible drainage. A special bedside drainage technique in critically ill patients also is described.

SI units and the clinical practice of infectious diseases: application to the usage of antimicrobial agents

Over the next few years, le Système international d'Unités or SI units may replace the presently used metric system in reporting laboratory data. The change to SI units will likely result in some confusion among clinicians who are not well versed in the new system. Application of SI units to the clinical practice of infectious diseases is discussed, including changes in drug dosages, serum drug levels, and minimum inhibitory concentrations. A table is presented to facilitate conversion of metric units to SI units and vice versa.

Regulation of receptor-mediated calcium influx across the plasma membrane in a human leukemic T-cell line: evidence of its dependence on an initial calcium mobilization from intracellular stores

It has been repeatedly shown that stimulation of a human leukemic T-cell line, JURKAT, by lectins such as phytohaemagglutinin and anti-T3 antibody (OKT3) leads to an elevation in the concentration of cytosolic free Ca2. This Ca2+ transient results from both an intracellular mobilization and an influx of Ca2+ through specific membrane channels. The objective of this study was to investigate the mechanism by which receptor-mediated influx of Ca2+ is regulated in JURKAT cells, which demonstrably lack 'voltage-dependent calcium channels'. It was found that upon increased loading with quin2 or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetate (BAPTA) there was a pronounced decline of both phytohaemagglutinin-stimulated and OKT3-stimulated influx of 45Ca2+. Using 15 microM quin2/AM or 30 microM BAPTA/AM, agonist-stimulated 45Ca2+ influx was almost totally abolished. At these concentrations of both quin2/AM or BAPTA/AM, phytohaemagglutinin and OKT3 could still induce a rise of cytosolic free Ca2+ above 200 nM. In the presence of La3+ (200 microM), which completely inhibited the agonist-induced 45Ca2+ influx, both phytohaemagglutinin and OKT3 were able to raise the concentrations of cytosolic free Ca2+ to well above 200 nM by merely mobilizing Ca2+ from intracellular stores alone. The data suggest that an agonist-induced increase in the concentration of cytosolic free Ca2+, due to mobilization from intracellular stores, could either directly or indirectly, initiate receptor-mediated Ca2+ influx across the plasma membrane in JURKAT cells.

IFN-gamma treatment of K562 cells inhibits natural killer cell triggering and decreases the susceptibility to lysis by cytoplasmic granules from large granular lymphocytes

Pretreatment of human K562 leukemia cells with rIFN-alpha and rIFN-gamma resulted in decreased susceptibility to lysis by human peripheral blood NK cells. The reduction of NK-susceptibility after IFN treatment was not due to a general effect of IFN on the stability of the cell membrane because the susceptibility of K562 cells to lysis by antibodies plus C, distilled water, or lysolecithin was unaffected. Binding studies with effector cell preparations enriched for NK cells with large granular lymphocyte morphology revealed no difference in binding to control and IFN-gamma-treated target cells. The sensitivity to soluble NK cytotoxic factors was not affected significantly by the IFN treatment. In contrast, the susceptibility of IFN-treated target cells to the cytotoxic activity of purified cytoplasmic granules from a rat large granular lymphocyte tumor was significantly reduced, indicating that the IFN-induced resistance acted at the level of susceptibility to the lytic mechanism of NK cells. However, IFN-alpha was more effective than IFN-gamma in inducing resistance to the cytoplasmic granules although resulting in only a weak resistance in the cell-mediated cytotoxic assay. IFN-gamma but not IFN-alpha caused a reduction in the frequency of effector cells that had reoriented their Golgi apparatus toward their bound target cell. In addition, IFN-gamma treated K562 cells failed to elicit an influx of Ca2+ into effector cells. Taken together, the results suggest that IFN-gamma in addition to an increased resistance to the lytic molecules released by NK cells can also induce changes in the target cells which prevent the triggering and activation of the effector cell.

IFN-gamma treatment of K562 cells inhibits natural killer cell triggering and decreases the susceptibility to lysis by cytoplasmic granules from large granular lymphocytes

Pretreatment of human K562 leukemia cells with rIFN-alpha and rIFN-gamma resulted in decreased susceptibility to lysis by human peripheral blood NK cells. The reduction of NK-susceptibility after IFN treatment was not due to a general effect of IFN on the stability of the cell membrane because the susceptibility of K562 cells to lysis by antibodies plus C, distilled water, or lysolecithin was unaffected. Binding studies with effector cell preparations enriched for NK cells with large granular lymphocyte morphology revealed no difference in binding to control and IFN-gamma-treated target cells. The sensitivity to soluble NK cytotoxic factors was not affected significantly by the IFN treatment. In contrast, the susceptibility of IFN-treated target cells to the cytotoxic activity of purified cytoplasmic granules from a rat large granular lymphocyte tumor was significantly reduced, indicating that the IFN-induced resistance acted at the level of susceptibility to the lytic mechanism of NK cells. However, IFN-alpha was more effective than IFN-gamma in inducing resistance to the cytoplasmic granules although resulting in only a weak resistance in the cell-mediated cytotoxic assay. IFN-gamma but not IFN-alpha caused a reduction in the frequency of effector cells that had reoriented their Golgi apparatus toward their bound target cell. In addition, IFN-gamma treated K562 cells failed to elicit an influx of Ca2+ into effector cells. Taken together, the results suggest that IFN-gamma in addition to an increased resistance to the lytic molecules released by NK cells can also induce changes in the target cells which prevent the triggering and activation of the effector cell.

Studies on the calcium dependence of human NK cell killing

T lymphocytes and NK cells depend on extracellular Ca2+ to mediate cellular cytotoxicity. In the present work, we have used pharmacological tools to analyze the nature of this calcium dependence. Ca2+ channel blockers like nifedipine greater than or equal to diltiazem greater than verapamil greater than cobalt chloride inhibited NK killing but at concentrations higher than those sufficient to block voltage-operated Ca2+ channels. Quercetin and TMB-8 also suppressed killing. Depolarization or NK cells with high K+ concentration resulted in partial inhibition of lysis in contrast to hyperpolarization with K+ ionophore valinomycin which had no effect. Depolarization of hyperpolarization in the presence of a protein kinase C activator (phorbol ester, TPA) did not initiate killing of NK resistant target cells. Of the two K+ channel inhibitors tested, 4-AP and TEA, only 4-AP was inhibitory for NK killing. No release of membrane-bound Ca2+ as judged by chlorotetracycline fluorescence could be detected in the NK cell population during binding to target cells although an influx of 45Ca2+ into the NK cell population was found. Treatment of NK cells with calcium ionophore A23187 did not trigger killing, but lysis could be induced by simultaneous stimulation with A23187 and TPA. The results indicate that NK killing depends on Ca2+ channels that are different from voltage operated channels and that intracellular Ca2+ may act in concert with protein kinase C activation.

Studies of gene transfer and reversion to mitomycin C resistance in Fanconi anemia cells

As a first step to the cloning of the Fanconi anemia (FA) gene, we have attempted to correct the sensitivity of FA cells to DNA crosslinking agents by the introduction of wild-type DNA. The protocol involved the introduction of both genomic and pRSVneo DNA, selection for G418-resistant colonies and the subsequent selection of mitomycin C-resistant cells from the latter. Preliminary experiments indicated that untransformed FA cells were not suitable recipients for the introduction of foreign DNA, so all experiments were performed with an SV40-transformed FA cell line. Approximately 40,000 G418-resistant colonies were obtained in 5 separate experiments at an overall frequency of about 5 X 10(-4). These were then selected in mitomycin C and 15 colonies were recovered. Colonies were obtained with wild-type DNA (both human and rodent) and with FA DNA at about the same frequency of 2 X 10(-7). Colonies were isolated and shown to have a stable, partial (from 25 to 90% of wild-type) resistance to mitomycin C. One colony was also shown to be partially resistant to two other DNA crosslinking agents, diepoxybutane and nitrogen mustard. This clone also had an intermediate level of spontaneous and MMC-induced chromosome aberrations. pRSVneo, but not rodent, DNA could be demonstrated in the high molecular weight fraction of several colonies. Thus, it is likely that these colonies represent partial revertants rather than transfectants. These mitomycin C-resistant FA cells should be useful for the biochemical analysis of the FA mutation.

The effects of high Na and Cl concentrations on rat proximal volume and Na fluxes at zero tubular flow

1. In vivo micropuncture techniques, with and without peritubular capillary perfusion, were used to study the effects of high extracellular Na and Cl concentrations on transepithelial volume (Jv) and sodium (JNa) fluxes in rat proximal tubules. 2. In a double blind manner, the shrinking drop technique of Gertz was used to measure Jv; JNa was calculated from this and the tubular fluid Na concentration. 3. At both 184 and 279 mmol/l pericellular Na concentrations (both inside and outside the tubular epithelium), net Jv decreased significantly by 15 and 64%, respectively. Net JNa remained constant at 184 but decreased by 29% at 279 mmol/l Na concentration. 4. Thus, at both Na concentrations, when translated to free flow conditions, fractional Na reabsorption must have decreased. These findings, also supported by previous results at these Na concentrations, indicate that active Na transport was inhibited by high pericellular Na concentrations. 5. When intratubular Cl concentration was varied between 108 and 138 mmol/l while peritubular Cl was maintained constant (blood perfusing the capillaries), neither Jv nor JNa changed. Thus, at zero tubular flow, differential Cl/HCO3 concentrations do not provide significant driving forces for net Jv or JNa. 6. When only intratubular but not peritubular Na was elevated to 279 mmol/l, Jv and JNa increased markedly by 50 and 187%, providing evidence that a true solvent drag (solute drag) effect does exist in rat proximal tubules. 7. These findings offer a mechanism to explain why Na reabsorption is not increased when the filtered load of Na is increased with an elevation of plasma Na.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of PHA and anti-T3 induced transduction mechanisms in a human T-cell leukaemia line

Stimulation of the T-cell line JURKAT with PHA or anti-T3 antibody leads to a rapid and sustained rise of cytosolic free Ca2+, as determined by quin2 fluorescence measurements. Pertussis toxin and N-ethylmaleimide, substances known to inactivate a regulatory N-protein, caused partial to complete inhibition of the cytosolic free Ca2+ response induced both by anti-T3 or PHA. The high cytosolic free Ca2+ level induced by anti-T3 or PHA declined more rapidly after addition of phorbol ester, phorbol myristate acetate (PMA). PMA did not affect cytosolic free Ca2+ changes induced by ionomycin indicating that the effect of PMA is due to a direct inhibitory effect on a transduction mechanism and not to activation of Ca2+ extrusion. Our data suggest that a regulatory N-protein is involved in the transduction of the PHA and anti-T3 response into a rapid and sustained elevation of cytosolic free Ca2+. Activation of protein kinase C by PMA modulates the calcium response in JURKAT cells, suggesting that protein kinase C may be involved in feedback regulation of the transduction mechanism.

Phorbol ester regulation of Ca2+ flux during natural, lectin and antibody-dependent killing

Phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C, suppresses natural, lectin and antibody-dependent killing by normal human lymphocytes in short-term radioisotope release assays. Fifty percent inhibition of killing of lymphoid target cells was seen at approximately 5 ng/ml TPA and inhibition was further potentiated by the presence of monocytic cells. In contrast, TPA increased killing of K-562 erythroleukaemic cells by non-adherent NK cells with optimal activity around 1 ng/ml. Two anti-estrogenic drugs, tamoxifen and clomiphene, known to inhibit protein kinase C, gave near to complete inhibition of NK killing at concentrations 12 microM and 30 microM, respectively. Retinal, another protein kinase C inhibitor, inhibited both antibody-dependent killing and lectin-dependent killing. An influx of 45Ca2+ into the effector population was found during effector-target cell conjugation and this flux was suppressed at TPA concentrations similar to those that suppressed killing. The results suggest that killing depends on a co-ordinated activation of protein kinase C together with a channel-dependent calcium influx. TPA may suppress killing by a negative feedback effect of protein kinase C on the hydrolysis of inositol phospholipids, as demonstrated in many other systems, or through the down-regulation of cell surface receptors required for triggering of lysis.