Location of Golgi membranes with reference to dividing nuclei in syncytial Drosophila embryos.

The role of cytoskeletal elements in thecellularization of syncytial Drosophila embryos is becoming evident; however,the distribution and role of organelles such as the Golgi complex, essential formembrane biogenesis, remain unknown. We have cloned a Golgi-membrane-associatedpolypeptide, beta-COP, from Drosophila. Immunocytochemical studies of syncytialDrosophila embryos with anti-Drosophila beta-COP antibody reveal that Golgimembranes are spatially segregated from the rapidly dividing nuclei. In earlyembryos, the Golgi membranes are located in the embryonic cortex and nuclei areconfined to the core. This distribution of Golgi membranes may serve inpreparation of the embryonic cortex for the accommodation of nuclei upon theireventual migration to the cortex and in biogenesis of the excessive plasmamembrane needed for cellularization of syncytial embryos.     

Testosterone and oxandrolone, a nonaromatizable androgen, specifically amplify the mass and rate of growth hormone (GH) secreted per burst without altering GH secretory burst duration or frequency or the GH half-life

We investigated the mechanisms by which androgens increase mean circulating GH concentrations in boys. We tested two hypotheses: 1) testosterone increases serum GH concentrations at least in part via an androgen receptor-mediated mechanism, rather than exclusively by way of aromatization to estrogen; 2) androgen augments one or more specific features to GH secretion (secretory burst number, amplitude, and/or duration) and/or prolongs the half-life of GH removal. To examine these hypotheses, prepubertal boys with constitutionally delayed development and/or growth were given injections of testosterone (100 mg monthly; n = 7) or treated with oral oxandrolone, a nonaromatizable androgen (1.25 mg twice daily; n = 5). Pulsatile GH release was studied before and during androgen administration by sampling blood at 20-min intervals for 24 h. The immunoreactive GH time series were subjected to a novel deconvolution technique, which revealed that 1) testosterone and oxandrolone each increased mean (24-h) serum GH concentrations significantly; 2) both androgens augmented the daily endogenous GH secretory rate significantly; 3) increased GH production resulted from a higher mass of GH secreted per burst and a higher maximal rate of GH secretion within each burst; and 4) androgens amplified the magnitude of the nyctohemeral rhythm in the mass (but not frequency) of GH secretory pulses. The observed effects of androgen were specific, since the number and duration of GH secretory bursts and the subject-specific GH half-life were unaltered by androgen treatment. We conclude that androgen acting apart from conversion to estrogen is capable of specifically activating the somatotropic axis via distinct neuroendocrine secretory mechanisms.     

Growth hormone deficiency predicts cardiovascular risk in young adults treated for acute lymphoblastic leukemia in childhood

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy, and until recently prophylactic cranial radiotherapy (CRT) was important for achieving long-term survival. Hypothalamic-pituitary hormone insufficiency is a well-recognized consequence of CRT for childhood cancer. Another problem is increased cardiovascular risk, which has been shown in long-term survivors of other childhood cancers. In the only previously reported study on cardiovascular risk after childhood ALL, obesity and dyslipidemia were recorded in a small subgroup treated with CRT, compared with patients treated with chemotherapy. The mechanisms behind the increase in cardiovascular risk in survivors of childhood cancer are not clarified.The aim of the present study was to elucidate mechanisms of increased cardiovascular risk in former childhood ALL patients. A group of 44 ALL survivors (23 males, median age 25 yr, range 19-32 yr at the time of study) treated with CRT (median 24 Gy, 18-30 Gy) at a median age of 5 yr (1-18 yr) and chemotherapy were investigated for prevalence of GH deficiency and cardiovascular risk factors. Comparison was made with controls randomly selected from the general population and individually matched for sex, age, smoking habits, and residence. All patients and controls underwent a GHRH-arginine test, and patients with a peak GH 3.9 microg/liter or greater were further investigated with an additional insulin tolerance test.Significantly higher plasma levels of insulin (P = 0.002), blood glucose (P = 0.01), and serum levels of low-density lipoprotein cholesterol, apolipoprotein (Apo) B, triglycerides, fibrinogen, and leptin (all P 相似文献   

Mutations of the SBDS gene are present in most patients with Shwachman-Diamond syndrome

Shwachman-Diamond Syndrome (SDS) is a rare multisystem disorder characterized by exocrine pancreatic insufficiency, bone marrow dysfunction, and metaphyseal chondrodysplasia. Recent studies show that mutations of SBDS, a gene of unknown function, are present in the majority of patients with SDS. In the present study, we show that most, but not all, patients classified based on rigorous clinical criteria as having SDS had compound heterozygous mutations of SBDS. Full-length SBDS protein was not detected in leukocytes of SDS patients with the most common SBDS mutations, consistent with a loss-of-function mechanism. In contrast, SBDS protein was expressed at normal levels in SDS patients without SBDS mutations. These data confirm the absence of SBDS mutations in this subgroup of patients and suggest that SDS is a genetically heterogeneous disorder. The presence (or absence) of SBDS mutations may define subgroups of patients with SDS who share distinct clinical features or natural history.     

Administration of pegylated recombinant human megakaryocyte growth and development factor to humans stimulates the production of functional platelets that show no evidence of in vivo activation

This report describes the effect of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) on platelet production and platelet function in humans. Subjects with advanced solid tumors received PEG-rHuMGDF daily for up to 10 days. There was no increase in circulating platelet count at doses of 0.03 or 0.1 microgram/kg/d by day 12 of study. At doses of 0.3 and 1.0 microgram/kg/d there was a threefold median increase (maximum 10-fold) in platelet count by day 16. The platelets produced in vivo in response to PEG-rHuMGDF showed unchanged aggregation and adenosine triphosphate (ATP)-release responses in in vitro assays. Tests included aggregation and release of ATP in response to adenosine diphosphate (ADP) (10, 5, 2.5, and 1.25 mumol/L), collagen (2 micrograms/mL), thrombin-receptor agonist peptide (TRAP, 10 mumol/L) and ristocetin (1.5 mg/mL). Administration of aspirin to an individual with platelet count of 1,771 x 10(3)/L resulted in the typical aspirin-induced ablation of the normal aggregation and ATP-release response to stimulation with arachidonic acid (0.5 mg/mL), collagen, and ADP (2.5 and 1.25 mumol/L). There was no change in the expression of the platelet-surface activation marker CD62P (P-selectin) nor induction of the fibrinogen binding site on glycoprotein IIb/IIIa as reported by the monoclonal antibody, D3GP3. An elevation of reticulated platelets was evident after 3 days of treatment with PEG-rHuMGDF and preceded the increase in circulating platelet count by 5 to 8 days; this reflected the production of new platelets in response to PEG-rHuMGDF. At later time points, the mean platelet volume (MPV) decreased in a manner inversely proportional to the platelet count. Levels of plasma glycocalicin, a measure of platelet turnover, rose 3 days after the initial increase in the peripheral platelet count. The level of plasma glycocalicin was proportional to the total platelet mass, suggesting that platelets generated in response to PEG-rHuMGDF were not more actively destroyed. Thus, the administration of PEG-rHuMGDF, to humans, increased the circulating platelet count and resulted in fully functional platelets, which showed no detectable increase in reactivity nor alteration in activation status.     

Effects of combined chelation treatment with pyridoxal isonicotinoyl hydrazone analogs and deferoxamine in hypertransfused rats and in iron-loaded rat heart cells

Although iron chelation therapy with deferoxamine (DFO) results in improved life expectancy of patients with thalassemia, compliance with parenteral DFO treatment is unsatisfactory, underlining the need for alternative drugs and innovative ways of drug administration. We examined the chelating potential of pyridoxal isonicotinoyl hydrazone (PIH) analogs, alone or in combination with DFO, using hypertransfused rats with labeled hepatocellular iron stores and cultured iron-loaded rat heart cells. Our in vivo studies using 2 representative PIH analogs, 108-o and 109-o, have shown that PIH analogs given orally are 2.6 to 2.8 times more effective in mobilizing hepatocellular iron in rats, on a weight-per-weight basis, than parenteral DFO administered intraperitoneally. The combined effect of DFO and 108-o on hepatocellular iron excretion was additive, and response at a dose range of 25 to 200 mg/kg was linear. In vitro studies in heart cells showed that DFO was more effective in heart cell iron mobilization than all PIH analogs studied. Response to joint chelation with DFO and PIH analogs was similar to an increase in the equivalent molar dose of DFO alone, rather than the sum of the separate effects of the PIH analog and DFO. This finding was most likely the result of iron transfer from PIH analogs to DFO, a conclusion supported directly by iron-shuttle experiments using fluorescent DFO. These findings provide a rationale for the combined, simultaneous use of iron-chelating drugs and may have useful, practical implications for designing novel strategies of iron chelation therapy.     

Meropenem monotherapy versus combination therapy with ceftazidime and amikacin for empirical treatment of febrile neutropenic patients

 Infections remain the major cause of morbidity and mortality among neutropenic cancer patients. The current study addresses the question whether monotherapy with the new broad-spectrum carbapenem meropenem exhibits efficacy comparable to that of the standard combination therapy with ceftazidime and amikacin for empirical treatment of febrile neutropenic patients. Seventy-one patients with hematological malignancies (55%) or solid tumors (45%), neutropenia <500/μl, and fever <38.5  °C were randomly assigned to either meropenem (1 g every 8 h) or ceftazidime (2 g every 8 h) and amikacin (15 mg/kg/day) intravenously. Meropenem (n=34) and ceftazidime/amikacin (n=37) were equivalent with respect to the clinical response at 72 h (62% versus 68%) (p<0.05) and at the end of unmodified therapy (59% versus 62%). Gram-positive bacteremia responded poorly in the meropenem and ceftazidime/amikacin group (29% versus 25%), whereas all gram-negative bacteremias responded except for one in the meropenem group caused by Pseudomonas aeruginosa. All patients survived to 72 h. One patient in each group died of gram-positive sepsis resistant to study medication. No significant side effects occurred in any regimen. This study suggests that meropenem monotherapy might be as effective as combination therapy with ceftazidime and amikacin for the empirical treatment of febrile neutropenic patients. Received: 13 June 1997 / Accepted in revised form: 5 December 1997     

The Relationship Between Discrimination and High-Risk Social Ties by Race/Ethnicity: Examining Social Pathways of HIV Risk

High-risk social ties portend differences in opportunity for HIV exposures and may contribute to racial/ethnic disparities in HIV transmission. Discrimination may affect the formation of high-risk social ties and has not been explored as a possible explanation for these persistent disparities. Using data from injection and non-injection drug users, we examined the association between the number of high-risk sex and drug ties with discrimination due to race, drug use, and incarceration stratified by race/ethnicity. Negative binomial regression models were used. While blacks had significantly fewer injecting ties than Latinos and whites, blacks who reported racial discrimination compared to blacks who did not, had more sex and injecting ties. Latinos who reported drug use discrimination compared to Latinos who did not also had more sex ties. Latinos and whites who reported drug use discrimination had more injecting ties than Latinos and whites who did not. Discrimination is associated with high-risk social ties among all racial/ethnic groups. But, these data highlight different forms of discrimination within racial/ethnic group are associated with risky social ties. More research is needed to confirm these findings and further explore the association between various forms of discrimination and social ties that may help explain racial/ethnic disparities in HIV.     

Elevated monoclonal and polyclonal serum immunoglobulin free light chain as prognostic factors in B‐ and T‐cell non‐Hodgkin lymphoma

The serum immunoglobulin free light chain (FLC) assay quantitates free kappa (κ) and lambda (λ) light chains. FLC elevations in patients with diffuse large B‐cell lymphoma (DLBCL), Hodgkin lymphoma (HL), and chronic lymphocytic leukemia (CLL) are associated with an inferior survival. These increases in FLC can be monoclonal (as in myeloma) or polyclonal. The goal was to estimate the frequency of these elevations within distinct types of B‐cell and T‐cell non‐Hodgkin lymphoma (NHL) and whether the FLC measurements are associated with event‐free survival (EFS). We studied serum for FLC abnormalities using normal laboratory reference ranges to define an elevated κ or λ FLC. Elevations were further classified as polyclonal or monoclonal. Four hundred ninety‐two patients were studied: 453 B‐cell and 34 T‐cell NHL patients. Twenty‐nine % (142/453) of patients had an elevated FLC of which 10% were monoclonal elevations. Within B‐cell NHL, FLC abnormalities were most common in lymphoplasmacytic (79%), mantle cell (68%), and lymphomas of mucosa associated lymphoid tissue (31%); they were least common in follicular (15%). The hazard ratio (HR) for EFS in all patients was 1.41 (95% CI; 1.11–1.81); in all B‐cell NHL the HR was 1.44 (95% CI 1.11–1.96); in all T‐cell NHL the HR was 1.17 (95% CI 0.55–2.49). FLC abnormalities predicted an inferior OS (HR = 2.75, 95% CI: 1.93–3.90, P < 0.0001). The serum FLC assay is useful for prognosis in both B‐cell and T‐cell types of NHL. In B‐cell NHL further discrimination between a monoclonal and polyclonal elevation may be helpful and should be analyzed in prospective clinical trials. Am. J. Hematol. 89:1116–1120, 2014. © 2014 Wiley Periodicals, Inc.