Identification of an oncogenic form of the thrombopoietin receptor MPL using retrovirus-mediated gene transfer

Thrombopoietin and its receptor (MPL) are important regulators of megakaryopoiesis. We have identified an activating mutation of MPL using a combination of a retrovirus-mediated gene transfer and polymerase chain reaction-driven random mutagenesis. This point mutation causes a single amino acid substitution from Ser498 to Asn498 in the transmembrane region and abrogates factor-dependency of all interleukin-3-dependent cell lines tested. Murine interleukin-3- dependent Ba/F3 cells expressing the mutated but not the normal form of MPL were tumorigenic when transduced into syngeneic mice. Analysis of intracellular signaling pathways indicated that the mutant MPL protein constitutively activated two distinct signaling pathways, SHC-Raf-MAPK and JAK2-STAT3/STAT5.     

Subclinical renal dysfunction in rheumatoid arthritis

We studied renal function in 35 patients with chronic, seropositive rheumatoid arthritis (RA), of whom 7 had vasculitis, 10 had hypergammaglobulinemia, and 18 had neither of these 2 conditions. Findings included a decreased glomerular filtration rate in 8 patients, (micro)proteinuria in 11, a defective urine concentration in 10, and increased urinary tubular enzyme levels in 15. These results indicate that subclinical renal dysfunction is common in patients with chronic, seropositive RA. In addition, vasculitis and hypergammaglobulinemia were not identified as risk factors for renal dysfunction in the RA patients studied.     

High-frequency chest wall oscillation. Assistance to ventilation in spontaneously breathing subjects

In five supine normal subjects breathing spontaneously, we studied the effects of high-frequency chest wall oscillation (HFCWO), which was achieved by oscillating the pressure in an air-filled cuff wrapped around the lower thorax. Oscillations of 3.5 and 8 Hz (in randomized order) were applied for 15 minutes each at both maximal (mean of 90 to 102 cm H2O) and half-maximal peak tolerable cuff pressures. Fifteen minutes of control spontaneous ventilation preceded each HFCWO maneuver. The HFCWO resulted in a significant decrease in spontaneous minute ventilation (VES) at maximal and half-maximal pressures by 35 and 40 percent, respectively, at 3 Hz and by 26 and 35 percent, respectively, at 5 Hz, with little change in VES at 8 Hz. This occurred despite an unchanging arterial carbon dioxide tension at all frequencies. Arterial oxygen pressure increased at 3 Hz at maximal pressure but remained statistically unchanged at 3 Hz at half-maximal pressure and at 5 Hz and 8 Hz both at maximal and half-maximal pressures. We conclude that HFCWO may potentially assist ventilation in spontaneously breathing man without requiring an endotracheal tube.     

Fluorescent labeling of hormone receptors in viable cells: preparation and properties of highly fluorescent derivatives of epidermal growth factor and insulin.

Highly fluorescent analogs of insulin and epidermal growth factor were prepared by the covalent attachment of these peptides to alpha-lactalbumin molecules that were highly substituted (i.e., seven to one) with rhodamine molecules. The alpha-lactalbumin was specifically linked to the lysine residue of insulin or to the alpha-amino group of epidermal growth factor. The insulin derivative retained 1.15% of its potency in stimulating glucose oxidation in fat cells but retained about 8.3% of its binding affinity toward receptors. The epidermal growth factor derivative was completely active in binding to fibroblast receptors and 40% as potent as the native hormone in stimulating DNA synthesis. These highly fluorescent derivatives were suitable for the specific visual labeling of receptor sites in viable cells and for measuring the lateral mobilities of the receptor-hormone complexes by fluorescent photobleaching recovery techniques. By these methods it was shown that the hormone-receptor complexes can move laterally in the plane of the plasma membrane with a diffusion coefficient of (3-5) X 10(-10) cm2/sec.     

Role of copper in mitochondrial iron metabolism

Heme synthesis by copper-deficient cells was investigated to elucidate the nature of the defect in intracellular iron metabolism. Iron uptake from transferrin by copper-deficient reticulocytes was 52% of normal, and the rate of heme synthesis was 33% of normal. Hepatic mitochondria isolated from copper-deficient animals were deficient in cytochrome oxidase activity and failed to synthesize heme from ferric iron (Fe III) and protoporphyrin at the normal rate. The rate of heme synthesis correlated with the cytochrome oxidase activity. Heme synthesis from Fe(III) and protoporphyrin by normal mitochondria was enhanced by succinate and inhibited by malonate, antimycin A, azide, and cyanide. It is proposed that an intact electron transport system is required for the reduction of Fe(III), thereby providing a pool of ferrous iron (Fe II) for protoheme and heme a synthesis.     

吸烟对支气管哮喘患者气道炎症及肾上腺皮质激素治疗效果的影响

目前糖皮质激素是治疗支气管哮喘（简称哮喘）的最有效的抗炎药，可有效抑制气道炎症，改善患者的临床症状、肺功能和气道高反应性。但以上研究一般都针对非吸烟群体，从而把多达1／3吸烟的哮喘患者排除在研究范围之外。可以说吸烟对哮喘患者气道炎症的影响，以及吸烟的哮喘患者对肾上腺皮质激素治疗的反应性如何都被忽略了。     

Evidence for abnormal granulosa cell responsiveness to follicle-stimulating hormone in women with polycystic ovary syndrome

Women with polycystic ovary syndrome (PCOS) undergoing ovulation induction appear to be extremely sensitive to gonadotropin stimulation and at increased risk for ovarian hyperstimulation syndrome. To determine granulosa cell responsiveness to recombinant human FSH (r-hFSH), dose-response studies were conducted in 16 individual PCOS patients and 7 normal women. Each subject received an iv injection of r-hFSH at doses of 0, 37.5, 75, or 150 IU in a randomized fashion on four separate occasions. Blood samples were obtained at frequent intervals before and for 24 h after r-hFSH administration for measurement of gonadotropins and steroid hormones. Our results showed that administration of r-hFSH produced instantaneous and equivalent dose-related increases in serum FSH in PCOS and normal women, which were followed by similar exponential decreases to baseline levels within 24 h in both groups. In PCOS subjects, the peak mean incremental response of serum estradiol (E(2)) to 150 IU of r-hFSH was 1.8-fold greater (P < 0.0001) and considerably accelerated compared with that found in normal women. In contrast, E(2) responses to 37.5 IU and 75 IU were similar between groups. Regression analysis of maximal E(2) concentrations in response to r-hFSH in each individual subject revealed that the slope of the linear trend line in the group of women with PCOS (r = 0.82) was significantly greater (P < 0.01) than that of normal controls (r = 0.71). The time-course of response revealed that in PCOS women, increases of E(2) were not sustained, compared with those of normal controls, because peak concentrations were followed by an estimated 40% decrement in circulating levels, whereas E(2) levels in normal women persisted for 24 h after reaching maximal values. These findings indicate that women with PCOS exhibit a significantly greater capacity for E(2) production in response to iv r-hFSH, compared with normal women. In PCOS, E(2) production was relatively transient because after peak concentrations a marked decline was detected at each dose, unlike normal women who exhibited persistent elevations of E(2) for up to 24 h. That this distinction was dose-dependent supports the concept of an FSH dose-response threshold, beyond which PCOS but not normal women are susceptible to ovarian hyperresponsiveness.     

Comparison of clinical manifestations and epidemiology between acute hepatitis A and acute hepatitis E in Taiwan

BACKGROUND AND AIMS: Acute hepatitis A (AHA) and acute hepatitis E (AHE) are endemic in developing countries. They share similar transmission routes and clinical manifestations. To compare the differences in epidemiology, clinical picture and prognosis between these two enterically transmitted forms of hepatitis, we enrolled 58 consecutive AHA or AHE patients (42 men and 16 women; age 16-74 years) from January 1990 to April 2001. RESULTS: In comparison to AHA, patients with AHE were older (56.2 +/- 15.4 vs 30.7 +/- 11.0 years, P < 0.0001), and more frequently had a history of travel within 3 months before onset of illness (68.8 vs 30.8%, P = 0.003). In laboratory data, AHE patients had lower serum levels of albumin (3.4 +/- 0.4 vs 3.8 +/- 0.4 g/dL, P = 0.016), alanine aminotransferase (1912 +/- 1587 vs 3023 +/- 1959 U/L, P = 0.015), and aspartate aminotransferase (1681 +/- 1444 vs 2374 +/- 2869 U/L, P = 0.24), but a higher serum bilirubin level (17.8 +/- 12.3 vs 8.7 +/- 5.0 mg/dL, P = 0.003) than AHA patients. Moreover, five (15.6%) patients with AHE compared with none with AHA died. This probably indicates that AHE had a worse outcome than AHA in our study. In analysis of epidemiological factors, older age of onset of illness was the only significant predicator of outcome. From an epidemiological survey, most AHE patients were imported while most AHA patients were not. However, native AHE and imported AHA did occur in Taiwan. CONCLUSION: Patients with AHE in Taiwan had older age of onset, more records of traveling history, and poorer clinical manifestations than those with AHA, and age seemed to be the most important factor to influence outcome.     

{beta}-thalassemia major evolution from {beta}-thalassemia minor is associated with paternal uniparental isodisomy of chromosome 11p15

beta-thalassemia major can be caused by homozygosity or compound heterozygosity for beta-globin gene mutations (HBB gene). Most cases are inherited from parents who both have diseased alleles of the HBB gene. We report a patient with late-onset beta-thalassemia major that evolved from beta-thalassemia minor in which only one of her parents had the diseased HBB gene. To study the cause of beta-thalassemia major in this patient, we performed the 100K single nucleotide polymorphism genotyping assay, fluorescence in situ hybridization, and DNA methylation analysis of the imprinting genes near the HBB gene. The results showed a loss of heterozygosity in the region of chromosome 11p14.3 to 11p15.5, which perfectly matched one allele of her father. Our study demonstrates that paternal uniparental isodisomy of chromosomal 11p15.5 is associated with the beta-thalassemia major in this patient. Key words: beta-thalassemia major, uniparental isodisomy, mosaicism.