Gender difference in allergic airway remodelling and immunoglobulin production in mouse model of asthma

BACKGROUND AND OBJECTIVE

Epidemiological studies have shown that the prevalence of adult asthma and severe asthma is higher in women. It has also been reported that female mice are more susceptible than males to the development of allergic airway inflammation and airway hyperresponsiveness (AHR). The influence of gender difference in the pathogenesis of severe asthma, especially airway remodelling in an animal model, has been studied rarely. We investigated gender difference in the development of airway remodelling using a long-term antigen-challenged mouse asthma model.

METHODS

Following ovalbumin (OVA)/alum intraperitoneal injection, male or female mice (BALB/c) were challenged with aerosolized 1% OVA on 3 days/week for 5 weeks, and differences in AHR, airway inflammation and airway remodelling between the sexes were investigated.

RESULTS

In OVA-sensitized and OVA-challenged (OVA/OVA) female mice, eosinophils, lymphocytes, T-helper type 2 cytokines and growth factors in bronchoalveolar lavage fluid were increased compared with OVA/OVA male mice. Histological features of airway remodelling were also increased in OVA/OVA female mice. Serum total and OVA-specific immunoglobulin E (IgE) and serum IgA were significantly elevated in OVA/OVA female mice.

CONCLUSIONS

These results indicate that female mice experience more airway remodelling compared with male mice. These results suggest the involvement of sex hormones and gender differences in cellular functions in airway remodelling.

Obesity and eosinophilic inflammation: does leptin play a role

It has been pointed out that obesity is a risk factor for, and is involved in the exacerbation of asthma. Mounting evidence about adipose tissue-derived proteins (adipokines) gave rise to the current understanding of obesity as a systemic inflammatory disorder. In this review, we summarized the involvement of leptin, focusing on eosinophil functions. Several studies have indicated that leptin can restrain eosinophil apoptosis, enhance migration, increase adhesion molecules and induce cytokine production. Since leptin also acts on a variety of immune cells related to allergic response, increased leptin in obese individuals potentially explains the mechanism by which obesity leads to an exacerbation of asthma. Further studies targeting adipokines will delineate the association between obesity and eosinophil-associated diseases.

Leptin has a priming effect on eotaxin-induced human eosinophil chemotaxis

BACKGROUND

Tissue eosinophilia is one of the hallmarks of allergic diseases and Th2-type immune responses including asthma. Systemic inflammation caused by adipose tissue in obesity via production of adipokines such as leptin has been attracting attention recently as a contributor to exacerbation of allergic immune reactions. In this study, we examined whether leptin might affect eosinophil chemotactic responses.

METHODS

Peripheral blood eosinophils were purified, and the effect of leptin on eosinophil migration was investigated using in vitro systems.

RESULTS

High concentrations of leptin induced eosinophil chemotaxis and rapid phosphorylation of ERK1/2 and p38 mitogen-activated protein kinase but not calcium mobilization. We also found that pretreatment of eosinophils with physiological concentrations of leptin amplified the chemotactic responses to eotaxin. This leptin-primed chemotaxis appears to be associated with increased calcium mobilization but not with ERK1/2 and p38 pathways.

CONCLUSIONS

These results indicate that leptin has both direct and indirect effects on eosinophil chemotaxis and intracellular signaling. In physiological settings, leptin may maintain eosinophil accumulation at allergic inflammatory foci.

Antibiotic sensitivity and plasmid profiles of Pseudomonas aeruginosa

OBJECTIVE

To determine the susceptibility of Pseudomonas aeruginosa to commonly used antibiotics and to study the relationship between antibiotic resistance and the plasmid profiles of the organism.

DESIGN

Cross sectional study

SETTING

Samples of burns, wound pus, urine, blood, sputum, stool and aspirates were obtained from Harare Hospital (n = 120) and Parirenyatwa Hospital(n = 80).

SUBJECTS

Male and female patients either admitted or attending clinics.

MAIN OUTCOME MEASURES

P. aeruginosa isolates obtained were resistant to commonly used antibiotics in this environment. The resistance may be plasmid-dependent.

RESULTS

P. aeruginosa is prevalent in burns (76.7%) and wounds (67.5%) and in their respective hospital wards. The isolates of P. aeruginosa were resistant to gentamicin (65.5%); carbenicillin (61.9); polymyxinb (53.0%); ciprofloxacin (61.1%) and ceftriazone (70.8%); but showed high sensitivity to tazocin (89.4%) and nalidixic acid (59.3%) and cotrimoxazole (54.9%). All the isolates resistant to the antibiotics tested possessed plasmid DNA. Strains with four plasmids of molecular weight of approximately, 1.5 x 10(6), 1.8 x 10(6), 2.9 x 10(6) and 7.4 x 10(6) Da showed multiple resistance to the drugs that were tested.

CONCLUSION

This study reveals an emergence of multiple antibiotic-resistant strains of P. aeruginosa. The traditional drugs gentamicin, carbenicillin, ciproflaxacin, and polymyxin-b used for treatment of P. aeruginosa infections may no longer be reliable. Therefore, a newer drug such as tazocin and other rarely used drugs such as nalidixic acid should be considered for P. aeruginosa antibiotic therapy.

[A tuberculosis epidemic among four relatives who live in the neighborhood of index case]

A tuberculosis epidemic occurred among 4 relatives who live in the neighborhood of the index case. A thirty-three year old female was admitted to a hospital in July 1994 with high fever and cervical lymphoadenopathy. Culture examination of her sputum was positive for acid-fast bacilli and her chest X-ray showed diffuse small nodules. During the following sixteen months, five new patients with pulmonary tuberculosis were found among the relatives who lived in the neighborhood of the index case. The contact examination was first limited in her own family members, however, after detection of the second case, the examination was extended to other relatives living nearby, and another four patients were found. The results of PPD skin test of ten contact children showed strongly positive reaction, and chemoprophylaxis was indicated. Contacts examination is very important especially for patients with highly infectious tuberculosis.

Effect of natural menopause on serum levels of IGF-I and IGF-binding proteins: relationship with bone mineral density and lipid metabolism in perimenopausal women

The present study was performed to examine the effect of natural menopause on serum levels of IGF-I, IGF-binding protein (IGFBP)-2 and -3 as well as on bone mass and lipid metabolism in perimenopausal women. One hundred and twenty-one healthy Japanese women, who were 45-55 years old, were studied (71 premenopausal and 50 postmenopausal women 1-9 years after menopause). Bone mineral density (BMD) was measured at the middle third of the radius by using dual energy X-ray absorptiometry. Serum levels of IGF-I, but not those of IGFBP-2 or -3, were significantly reduced in the postmenopausal group compared with the premenopausal group. One year after menopause, serum IGF-I levels were significantly lower, and the biochemical markers of bone turnover, such as serum total alkaline phosphatase level and urinary calcium to creatinine ratio, were significantly higher than the premenopausal levels. Serum levels of IGF-I, but not those of IGFBP-2 or -3, were positively correlated with BMD. Serum levels of IGFBP-2, but not those of IGF-I or IGFBP-3, were negatively correlated with body mass index and body weight. Finally, serum levels of IGFBP-3, but not those of IGF-I, were positively correlated with serum levels of total cholesterol and triglyceride. The present findings suggest that a rapid decrease in serum IGF-I levels after menopause might be partly involved in bone loss following gonadal failure and that IGFBP-2 and -3 might be related to the regulation of body mass and lipid metabolism during perimenopause respectively, although the mechanisms remain unknown.

Photorefractive effect in GaP

The photorefractive effect in undoped semi-insulating GaP was observed. GaP has a photorefractive sensitivity in the spectral region of 0.6 to 0.9 microm. The photorefractive center is the deep donor resulting from the P antisite defect. We measured the two-beam coupling gain coefficient and its time constant as functions of the grating period and the pumping intensity, using a 633-nm He-Ne laser. The maximum gain coefficient of 0.33 cm(-1) was obtained at a grating period of 1.1 microm. The time constant, which depends on the grating period, was 3-20 msec at a pumping intensity of 30 mW/cm(2).

Effects of exogenous phospholipase enzymes, arachidonic acid and 1-oleoyl-2-acetyl-sn-glycerol on ketogenesis in isolated rat hepatocytes

Studies were conducted to see whether exogenous phospholipase C from Clostridium perfringens, phospholipase A2 from Crotalus adamanteus venom, arachidonic acid and 1-oleoyl-2-acetyl-sn-glycerol (OAG) mimic the anti-ketogenic action of vasopressin in isolated rat hepatocytes. Exogenous phospholipase C inhibited ketogenesis in the presence of 0.5 mM oleate. Experiments employing [1-14C]oleate, however, indicated that the mechanism involved in the anti-ketogenic action of exogenous phospholipase C is distinct from that of vasopressin. The decreased rate of the production of acid-soluble products from [1-14C]oleate in response to vasopressin could be explained by the sum of the increased rates of 14CO2 formation and [1-14C]oleate esterification. By contrast, exogenous phospholipase C suppressed not only the formation of acid-soluble products but also 14CO2 production and [1-14C]oleate esterification. Indeed, phospholipase C greatly inhibited [1-14C]oleate uptake into hepatocytes. It is suggested that the alteration of the architecture of plasma membrane by exogenous phospholipase C may lead to the disturbance of oleate uptake and consequent general suppression of oleate metabolism. Exogenous phospholipase A2, arachidonic acid and OAG increased ketogenesis regardless of the presence of oleate. The ketogenic effects may be attributed to the supply of fatty acids by these agents to hepatocytes.

Intermittent versus long-term tapering prednisolone for initial therapy in children with idiopathic nephrotic syndrome

Forty-six children with steroid-responsive nephrotic syndrome were randomly allocated to receive two different prednisolone regimens for initial therapy. Twenty-nine children (group 1) received an intermittent regimen (60 mg/m2/day for 4 weeks, followed by 40/mg/m2/day on 3 days a week for 4 weeks); 17 children (group 2) had a long-term regimen (60 mg/m2/day for 4 weeks, followed by the same dose on alternate days for 4 weeks and the doses tapered by 10 mg/m2, given on alternate days every 4 weeks for 5 months). There was no difference between the two groups in the regimen used to treat relapses, steroid responsiveness, number of patients with relapses, and frequency of toxic reactions to steroids. However, the number of patients with a relapse within 6 months after initial therapy and the number of those with frequent relapses or steroid dependence were significantly higher in group 1 than in group 2 (P less than 0.05 for both). The data indicate that the long-term tapering regimen appears to be both safe and preferable to the intermittent regimen for initial therapy in children with idiopathic nephrotic syndrome.

Atrial fibrillation following methylprednisolone pulse therapy

Two children, one with renal manifestations of systemic lupus erythematosus and the other with idiopathic nephrotic syndrome, were treated with methylprednisolone pulses. Neither had previous evidence of underlying cardiac disease. Within 24 h of pulse therapy, they complained of palpitations and developed atrial fibrillation which reversed spontaneously or after anti-arrhythmic therapy. Subsequent serial electro- and echocardiograms were normal. We propose that the arrhythmias were a complication of steroid pulse therapy.

Effects of phorbol esters, A23187 and vasopressin on oleate metabolism in isolated rat hepatocytes

Studies were conducted to compare the metabolic effects of vasopressin, 4 beta-phorbol-12-myristate-13-acetate (PMA) and A23187 on ketogenesis and oleate metabolism in isolated hepatocytes from fed rats. Vasopressin inhibited the formation of acid-soluble products from [1-14C]oleate (0.25 mM, 0.5 mM and 1 mM), the inhibition being most marked at low (0.25 mM) concentration of oleate. Conversion of [1-14C]oleate into 14CO2 and esterified products was stimulated by vasopressin. The stimulatory effect of this hormone on 14CO2 production was most marked at high (1 mM) concentration of oleate, whereas that on [1-14C]oleate esterification was most marked at low (0.25 mM) concentration of oleate. These vasopressin actions were abolished when hepatocytes were incubated in the absence of calcium in the medium. Our results strongly suggest that both increase in esterification and increase in oxidation to CO2 contribute to the anti-ketogenic action of vasopressin when oleate is added as substrate, although the relative extent of their contribution varies according to the oleate concentration. The anti-ketogenic action of vasopressin was mimicked by PMA but not by A23187. PMA also caused a stimulation of [1-14C]oleate esterification although the effect was diminished at 1 mM [1-14C]oleate. A23187 failed to affect [1-14C]oleate esterification. The metabolic effects of PMA were elicited in the absence of extracellular calcium, too. Conversion of [1-14C]oleate into 14CO2 was only slightly increased by both PMA and A23187 when 1 mM [1-14C]oleate was added as substrate. The marked stimulatory effect of vasopressin on 14CO2 production from [1-14C]oleate was not reproduced even by the combination of PMA and A23187.(ABSTRACT TRUNCATED AT 250 WORDS)

Homology of Escherichia coli B glutathione synthetase with dihydrofolate reductase in amino acid sequence and substrate binding site

Glutathione synthetase from Escherichia coli B showed amino acid sequence homology with mammalian and bacterial dihydrofolate reductases over 40 residues, although these two enzymes are different in their reaction mechanisms and ligand requirements. The effects of ligands of dihydrofolate reductase on the reaction of E. coli B glutathione synthetase were examined to find resemblances in catalytic function to dihydrofolate reductase. The E. coli B enzyme was potently inhibited by 7,8-dihydrofolate, methotrexate, and trimethoprim. Methotrexate was studied in detail and proved to bind to an ATP binding site of the E. coli B enzyme with K1 value of 0.1 mM. The homologous portion of the amino acid sequence in dihydrofolate reductases, which corresponds to the portion coded by exon 3 of mammalian dihydrofolate reductase genes, provided a binding site of the adenosine diphosphate moiety of NADPH in the crystal structure of dihydrofolate reductase. These analyses would indicate that the homologous portion of the amino acid sequence of the E. coli B enzyme provides the ATP binding site. This report gives experimental evidence that amino acid sequences related by sequence homology conserve functional similarity even in enzymes which differ in their catalytic mechanisms.

Studies on the mechanism of growth hormone and thyrotropin responses to somatostatin antiserum in anesthetized rats

An iv administration of 1 ml sheep antiserum to somatostatin (anti-SS) resulted in marked increases of both serum GH and TSH, with a peak 10--20 min after administration in male rats anesthetized with urethane or pentobarbital. Administration of anti-SS had no effect on serum PRL. Ablation of the basal medial hypothalamus abolished the rises of both serum GH and TSH after anti-SS administration. Intravenous injection of 1 ml rabbit antiserum to TRH (anti-TRH) decreased serum TSH levels 15 min after injection, whereas injection of normal rabbit serum did not affect TSH levels. Serum TSH levels did not rise after injection of anti-SS in rats pretreated with anti-TRH. On the other hand, pretreatment with anti-TRH did not affect the basal serum GH levels nor the anti-SS-induced GH release. The enhanced secretion of GH and TSH after anti-SS injections was not blocked by pretreatment with indomethacin, an inhibitor of prostaglandin synthesis. The following conclusions were made: 1) both GH and TSH responses to anti-SS require an intact basal medial hypothalamus; (2) TSH response to anti-SS is mediated by hypothalamic TRH; and 3) the GH response may be mediated by hypothalamic GH-releasing hormone which is not TRH or prostaglandins.

Effect of intraventricular administration of anti-somatostatin gamma-globulin on the lethal dose-50 of strychnine and pentobarbital in rats

Effects of intraventricular injection of sheep anti-somatostatin gamma-globulin (anti-SSG) on strychnine-induced seizures, strychnine LD50, and pentobarbital LD50 were examined in male rats under light ether anesthesia. Ten microliters of anti-SSG given 2 h earlier significantly decreased the duration of strychnine-induced seizures as compared with that in the control rats pretreated with normal sheep gamma-globulin (NSG). This effect of anti-SSG seemed to be specific, as there was no difference in seizure duration between sheep anti-LHRH gamma-globulin (anti-LHRHG)- and NSG-pretreated rats. Survival rates in anti-SSG-pretreated rats after injection of strychnine and pentobarbital were significantly larger (P less than 0.01 and P less than 0.05, respectively) than those in the control rats receiving NSG. The administration of anti-SSG resulted in 26.7% and 22.9% increases in the LD50 of strychnine and pentobarbital, respectively. These results indicate that endogenous somatostatin in the cerebrospinal fluids and/or the periventricular tissue nodulates the response of the central nervous system to strychnine and pentobarbital in rats.