Expression of ferritin receptor in placental microvilli membrane in pregnant women with different iron status at mid-term gestation

OBJECTIVE

The effect of iron status in pregnant women on expression of ferritin receptor in placental microvilli membrane at mid-term gestation was investigated.

DESIGN

Ferritin receptor binding sites and dissociation constants (K(d)) were determined in specimens of placental microvilli from 30 pregnant women at mid-term gestation and six women at term-delivery.

RESULTS

The ferritin receptor binding sites in the placental microvilli membrane in pregnant women with mild iron deficiency and moderate iron deficiency anemia were significantly higher then those in pregnant women with normal iron status. However, no significant difference was found between pregnant women with severe iron deficiency anemia and with normal measurements. No significant differences of K(d) values were detected between pregnant women with normal iron status and those with iron-deficiency. Data also revealed that the ferritin receptor binding sites in placental microvilli membrane and K(d) values at mid-term gestation did not differ significantly from those at term gestation.

CONCLUSION

Lower iron status in pregnant women could lead to an increase in expression of ferritin receptor in placental microvilli membrane at mid-term gestation while the dissociation constant of ferritin receptor remains unchanged. This implies that the regulation of maternal-fetal iron homeostasis via the ferritin receptor-mediated pathway is achieved by changes in the numbers of ferritin receptors rather then binding properties.

Human mitochondrial DNA deletions associated with mutations in the gene encoding Twinkle, a phage T7 gene 4-like protein localized in mitochondria

The gene products involved in mammalian mitochondrial DNA (mtDNA) maintenance and organization remain largely unknown. We report here a novel mitochondrial protein, Twinkle, with structural similarity to phage T7 gene 4 primase/helicase and other hexameric ring helicases. Twinkle colocalizes with mtDNA in mitochondrial nucleoids. Screening of the gene encoding Twinkle in individuals with autosomal dominant progressive external ophthalmoplegia (adPEO), associated with multiple mtDNA deletions, identified 11 different coding-region mutations co-segregating with the disorder in 12 adPEO pedigrees of various ethnic origins. The mutations cluster in a region of the protein proposed to be involved in subunit interactions. The function of Twinkle is inferred to be critical for lifetime maintenance of human mtDNA integrity.

Characterization of a novel human putative mitochondrial transporter homologous to the yeast mitochondrial RNA splicing proteins 3 and 4

We report here a novel human gene, hMRS3/4, encoding a putative mitochondrial transporter structurally and functionally homologous to the yeast mitochondrial RNA splicing proteins 3 and 4. These proteins belong to the family of mitochondrial carrier proteins (MCF) and are likely to function as solute carriers. hMRS3/4 spans approximately 10 kb of genomic DNA on chromosome 10q24 and consists of four exons that encode a 364-aa protein with six transmembrane domains. A putative splice variant, encoding a 177-aa protein with three transmembrane domains, was also identified. hMRS3/4 has a well-conserved signature sequence of MCF and is targeted into the mitochondria. When expressed in yeast, hMRS3/4 efficiently restores the mitochondrial functions in mrs3(o)mrs4(o) knock-out mutants. Ubiquitous expression in human tissues and a well-conserved structure and function suggest an important role for hMRS3/4 in human cells.

Mechanical unfolding and refolding of proteins: an off-lattice model study

Using an off-lattice model, we investigate the response of a protein molecule to external stretching and release. In particular we study the passive force in a protein as a function of the extension of the protein. These force-extension curves exhibit hysteresis loops, whose areas increase with the pulling rate and decrease with thermal noise. Most of these results seem to be appropriately described by a cusp catastrophe.

Application of a fluorescent histone acetyltransferase assay to probe the substrate specificity of the human p300/CBP-associated factor

Histone N-acetyltransferases (HATs) are a group of enzymes which acetylate specific lysine residues in the N-terminal tails of nucleosomal histones to promote transcriptional activation. Recent structural and enzymatic work on the GCN5/PCAF HAT family has elucidated the structure of their catalytic domain and mechanism of histone acetylation. However, the substrate specificity of these enzymes has not been quantitatively investigated. Utilizing a novel microplate fluorescent HAT assay which detects the enzymatic production of coenzyme A (CoA), we have compared the activities of the HAT domains of human PCAF and its GCN5 homologue from yeast and Tetrahymena and found that they have similar kinetic parameters. PCAF was further assayed with a series of different length histone H3 peptide substrates, which revealed that the determinants for substrate recognition lie within a 19-residue sequence. Finally, we evaluated the acetylation of three putative PCAF substrates, histones H3 and H4 and the transcription factor p53, and have determined that histone H3 is significantly preferred over the histone H4 and p53 substrates. Taken together, the fluorescent acetyltransferase assay presented here should be widely applicable to other HAT enzymes, and the results obtained with PCAF demonstrate a strong substrate preference for the N-terminal residues of histone H3.

Photoelectrochemical Response of Langmuir-Blodgett Monolayer Films Containing Donor-pi-Acceptor Azomethine Dyes

Three amphiphilic azomethine dyes, (E)-N-octadecyl-2-[2-(4-N, N-dimethylaminophenyl)azomethinyl]quinolinium tiodide, (E)-N-octadecyl-4-[2-(4-N, N-dimethylaminophenyl)azomethinyl]quinolinium iodide, and (E)-N-octadecyl-6-[2-(4-N, N-dimethylaminophenyl)azomethinyl]quinolinium iodide, have been prepared by changing different relative positions of electron-accepting groups. They were successfully transferred onto indium-tin oxide slides by the Langmiur-Blodgett (LB) technique. Photoelectrochemical studies on these dyes' LB monolayer-modified ITO electrode were carried out. In 0.5 M KI solution containing 0.05 M I(2), the photocurrent generation quantum yield for these dyes varied from 7.2 to 15.9%, depending on the linking positions. Dependence of the photocurrent on the applied potential and the redox couple suggests that they undergo the photoinduced electron transfer mechanism of photoelectric conversion. Copyright 2000 Academic Press.

Endotoxin induces a dose-dependent myocardial cross-tolerance to ischemia-reperfusion injury

OBJECTIVE

To test whether or not endotoxin induces a dose-dependent reduction of myocardial contractile dysfunction after a standardized period of myocardial ischemia and reperfusion and whether nitric oxide is involved in this form of myocardial protection.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University research laboratory.

SUBJECTS

Twenty-five male Sprague-Dawley rats.

INTERVENTIONS

After anesthesia, the left carotid artery was cannulated under sterile conditions and animals were allowed to recover from surgery for 12 hrs. Sterile saline or increasing doses (2.5, 5, or 10 mg/kg body weight) of endotoxin (Escherichia coli O26:B6; Sigma, Mississauga, Ontario, Canada) were given intravenously (1 mL over 5 mins). In some rats, diaspirin-crosslinked hemoglobin (200 mg/kg) was infused 6 hrs and 60 min before endotoxin infusion (10 mg/kg). Hearts were rapidly excised for retrograde perfusion through the ascending aorta (Langendorff apparatus) 6 hrs later. After baseline data collection, hearts were subjected to global ischemia (30 mins, 37 degrees C [98.6 degrees F]), followed by 30 mins of reperfusion.

MEASUREMENTS AND MAIN RESULTS

Physiologic variables were recorded 6 hrs after saline and endotoxin infusion. Baseline myocardial systolic contractility and diastolic compliance were assessed, respectively, by left ventricular developed pressure (LVDP) and left ventricular (LV) volume-preload relationships. After 30 min of reperfusion, LVDP recovery and left ventricular end-diastolic pressure were measured. Endotoxin induced LV systolic contractile depression, irrespective of the dose of endotoxin administered. LV diastolic dysfunction varied between different doses of endotoxin administered. On reperfusion, endotoxin produced a dose-dependent improvement of postischemic LVDP recovery: 30+/-6% in sham, 78+/-9% in 2.5 mg/kg, 93+/-8% in 5 mg/kg, and 107+/-10% in 10 mg/kg endotoxin heart. In rats treated with 10 mg/kg endotoxin, diaspirin-crosslinked hemoglobin pretreatment abrogated endotoxin-induced postischemic LVDP recovery improvement (105+/-10% vs. 43+/-7%, p = .01).

CONCLUSION

Sublethal doses of endotoxin induce in a dose-dependent manner a delayed form of myocardial protection against ischemia. Although free-cell hemoglobin solution abrogates this endotoxin-induced cross-tolerance, we propose that possible mechanisms involved in this form of myocardial protection include nitric oxide pathway activation.

Mapping of autosomal dominant progressive external ophthalmoplegia to a 7-cM critical region on 10q24

OBJECTIVE

To map the gene responsible for autosomal dominant progressive external opthalmoplegia.

BACKGROUND

The pathogenesis of progressive external ophthalmoplegia (PEO) can be associated with multiple deletions of mitochondrial DNA (mtDNA). PEO may show autosomal dominant (adPEO) or autosomal recessive (arPEO) patterns of inheritance, indicating that the genetic defect has a Mendelian basis and most likely involves a nuclear gene encoding a protein that interacts with the mitochondrial genome. adPEO is heterogeneous genetically, and thus far disease loci have been identified on chromosomes 3 and 10. The locus on chromosome 10q23-q25 was assigned by linkage analysis in a single Finnish family.

METHODS

Samples from a large Pakistani family with adPEO, in which clinical symptoms are bilateral ptosis, limitations of eye movements, and varying degrees of proximal muscle weakness, were collected. Muscle biopsy and mtDNA rearrangement analysis was used to confirm the diagnosis. Genomewide linkage analysis was set up using a set of 391 microsatellite markers.

RESULTS

The muscle biopsy from an affected member showed ragged red fibers, increased succinic dehydrogenase staining, lack of cytochrome oxidase activity, and multiple deletions of mtDNA. The disease locus was mapped to 10q23.31-q25.1 by linkage analysis, and a maximum lod score of 5.72 was obtained with D10S1267.

CONCLUSION

By analysis of meiotic recombinations in affected individuals, the critical region was restricted to the 7-cM interval between D10S198 and D10S1795.

[Membranectomy with intestinal-plasty for the treatment of duodenal and upper jejunal constrictive abnormalities]

OBJECTIVE

To sum up the experience of diagnosis and treatment of intrinsic upper gastro-intestinal membrane, 13 cases in children were studied retrospectively.

METHODS

There were 10 boys and 3 girls, the major symptoms were vomiting and epigastric distension. Eleven cases were treated by membranectomy with intestinal plasty, and 2 cases were treated by retrocolic side to end duodenojejunostomy.

RESULTS

All cases had good results without severe complications.

CONCLUSION

The children who have typical symptom of upper digestive tract should be considered duodental and upper jejunal membrane, and should be proved by contrast radiology. The membranectomy with intestinal plasty is the better operative method.

Effects of isoproterenol on myocardial structure and function in septic rats

In this study we sought to determine the effect of sepsis on two sequelae of prolonged (24-h) beta-agonist administration, myocardial hypertrophy and catecholamine-induced cardiotoxicity. Sprague-Dawley rats were randomized to cecal ligation and perforation (CLP) or sham study groups and then further randomized to receive isoproterenol (2.4 mg. kg-1. day-1 iv) or placebo treatment. At 24 h, myocardial function was assessed by using the Langendorff isolated-heart technique or the heart processed for plain light microscopy. We found that 1) sepsis reduced contractile function, indicated by a rightward shift in the Starling curve (ANOVA with repeated measures, sepsis effect, P < 0.002); 2) sepsis-induced myocardial depression was reversed by isoproterenol treatment (isoproterenol effect, P < 0.0001); 3) sepsis reduced, but did not block, isoproterenol-induced myocardial hypertrophy (isoproterenol effect, P < 0.0001); 4) sepsis did not protect the heart from catecholamine-induced tissue injury; 5) the septic heart was protected against the effects of ischemiareperfusion (decreased postreperfusion resting tension, ANOVA with repeated measures, P < 0.01), an effect attenuated by isoproterenol treatment (P < 0.005); and 6) sepsis reduced the incidence of sustained asystole or ventricular fibrillation after ischemia-reperfusion (P < 0.05), an effect also attenuated by isoproterenol treatment (P < 0.01). We conclude that, in sepsis, beta-agonists induce changes in myocardial weight and function consistent with acute myocardial hypertrophy. These changes occur at the expense of significant tissue injury and increased sensitivity to ischemia-reperfusion-induced tissue injury.

Genetic studies of a family with hereditary hyperparathyroidism-jaw tumour syndrome

BACKGROUND AND OBJECTIVES

Familial hyperparathyroidism may occur as familial isolated hyperparathyroidism (FIHP) or as part of an inherited syndrome, in particular multiple endocrine neoplasia types 1 and 2A (MEN1, MEN2A) and hyperparathyroidism-jaw tumour (HPT-JT) syndrome. The localization of the genes responsible for these syndromes has enabled genetic screening of families with primary hyperparathyroidism (PHPT) to be carried out. This has important clinical implications in terms of individual follow-up and management. We previously reported a large FIHP family with an increased risk of parathyroid cancer and excluded its linkage to MEN1, MEN2 and PTH genes. Here we re-analysed this family and performed genetic linkage to the HPT-JT locus in chromosome 1q21-q32. Loss of heterozygosity studies of 1q21-q32, 11q13 and X chromosome were also performed.

PATIENTS AND DESIGN

We studied 19 family members, aged 6-63 years. High molecular weight DNA was isolated from peripheral blood samples from 17 family members. For the two deceased individuals, DNA was extracted from normal paraffin embedded tissues.

MEASUREMENTS

All individuals (except two deceased patients) had serum corrected calcium, inorganic phosphate, intact PTH, prolactin and various pancreatic hormones, measured on fasting blood samples. Twenty microsatellite markers were examined for the 1q21-q32 region, the locus for the HPT-JT gene. Genetic polymorphisms were determined by polymerase chain reaction amplification of genomic DNA and genetic linkage analysis was performed. Loss of heterozygosity studies were performed using paraffin-embedded parathyroid tissues from four affected members.

RESULTS

Seven of the eight affected family members included in this study had biochemical evidence of PHPT and surgically proven parathyroid tumours. Indication of linkage of the disease to the HPT-JT locus was demonstrated with a maximum lod score of 2.32 by two-points linkage analysis. Linkage data were supported by multi-point analysis which gave a maximum lod score of 2.7. Meiotic recombinations detected in one affected individual narrowed the region to 26 cM. As a result of the genetic findings, we re-screened the living family members by orthopantomograph and renal ultrasound, and identified two jaw lesions in two gene carriers. One affected family member demonstrated polycystic kidney disease, thus establishing the association between the two conditions. A reduced penetrance of HPT in females was evident, in agreement with our previous study. No allelic deletion was detected in any tumour at 1q21-q32, 11q13 or X chromosome.

CONCLUSIONS

This study illustrates the usefulness and importance of genetic studies in familial isolated hyperparathyroidism families. Our clinical and genetic findings indicate that this previously reported familial isolated hyperparathyroidism family has hyperparathyroidism-jaw tumour syndrome.

Involvement of mu-opioid receptors and alpha-adrenoceptors in the immunomodulatory effects of dihydroetorphine

The present study investigated the effects of acutely administered dihydroetorphine on mitogen-stimulated lymphocyte proliferation and lymphokine production in mice. These immune functions were significantly suppressed by dihydroetorphine at 24 microg/kg and 128 microg/kg in a dose-dependent fashion. This study further examined the involvement of micro-opioid receptors and alpha-adrenoceptors in the immunomodulatory effects of dihydroetorphine. The micro-opioid receptor antagonist, naloxone (4 mg/kg), and alpha-adrenoceptor antagonist, phentolamine (10 mg/kg), but not the beta-adrenoceptor antagonist, propranolol (10 mg/kg), effectively blocked dihydroetorphine-induced suppression of splenic lymphocyte proliferation and lymphokine production. These results demonstrate that dihydroetorphine has significant immunosuppressive effects in mice and the mechanisms of these effects may lie in its interactions with opioid receptors and adrenergic pathways.

Immunosuppressive effects of intravenous self administration of dihydroetorphine on lymphocyte functions in rats

AIM

To study the effects of dihydroetorphine (DHE) on lymphocyte functions in rats and to further assess the abuse potential of DHE.

METHODS

An intravenous self administration (SA) procedure in rats was used to determine the SA liability of DHE. Concanavalin A (Con A)-stimulated lymphocyte proliferation and lymphokine production of rat splenocytes were measured.

RESULTS

DHE 178 +/- 13 micrograms established a stable and typical rat model of psychological dependence, suppressed lymphocyte proliferation (129 +/- 11 Bq) compared with control group (620 +/- 36 Bq), and inhibited the activity of interleukin-2 (IL-2) (A570 = 0.28 +/- 0.06) compared with control group (A570 = 0.51 +/- 0.03).

CONCLUSION

DHE had a high abuse potential and inhibited the Con A-induced lymphocyte proliferation and interleukin-2 production in rats.

Structure-function relationships in the septic rat heart

Myocardial edema and histologic changes consistent with tissue injury are reported in association with sepsis-induced myocardial depression. The objective of the present study was to determine whether, in the absence of shock, such changes (assessed by studying microvascular albumin flux, tissue edema, and morphometry) are prerequisites for the development of contractile dysfunction in sepsis. Sprague-Dawley rats were randomized into groups for either cecal ligation and perforation (CLP) or sham study. Twenty-four hours after entry of animals into the study, their myocardial function was assessed with the Langendorff isolated heart technique. Left-ventricular developed pressure (preload: 5 mm Hg) was reduced in CLP animals (34.9 +/- 3.3 mm Hg, n = 10) as compared with time-matched controls (46.4 +/- 4.0 mm Hg, n = 8, p < 0.05, unpaired t test). This was associated with a significant reduction in the maximal rate of increase (+ dP/dt(max)) and decrease (-dP/dt(max)) in left ventricular pressure in the CLP group (sham versus CLP, unpaired t test, p < 0.05). Upon reperfusion, after 30 min of ischemia, left ventricular resting tension was decreased in CLP as compared with sham-treated animals (sham versus CLP, analysis of variance (ANOVA) with repeated measures, p < 0.05). At 24 h, sepsis was not associated with myocardial edema (wet:dry weight ratio, sham = 4.094 +/- 0.098, n = 10; CLP = 4.185 +/- 0.066, n = 7), and tissue albumin flux was reduced (sham = 194 +/- 27 microliters. h-1. g dry wt-1, n = 10; CLP = 100 +/- 14 microliters. h-1. g dry wt-1, n = 7). In tissue processed for electron microscopy, we found no evidence of tissue injury or edema at either 24 or 48 h after CLP. We conclude that polymicrobial normotensive sepsis causes myocardial contractile depression in the absence of changes in myocardial structure.

Oculopharyngeal muscular dystrophy (OPMD)--report and genetic studies of an Australian kindred

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset autosomal dominant disease. Due to a founder effect, it is most commonly found in the French Canadian population. The gene has recently been mapped to chromosome 14q11.2-q13 in some of these families. Here we report an Australian kindred of German descent with OPMD. Linkage analysis supports its locus to chromosome 14q. Repeat expansion studies were also carried out, but a CAG trinucleotide repeat expansion detected did not cosegregate with the disease. We conclude that there is no evidence of genetic heterogeneity or involvement of repeat expansion in OPMD.

[Surgical treatment of constrictive pericarditis in 162 cases]

The authors reports the experience of surgical treatment of constrictive pericarditis in 162 cases. Age ranged from 6 to 66 years old. The cardiac function and circulatory dynamics were improved after decortication of the thickened pericardium in most of the patients. Overall surgical mortality was 3.1%. The major cause of death was low cardiac output syndrome in the early postoperative period. The authors consider that the excision of the thickened pericardium is better to begin from the left to right and the good perioperative management particularly the rational agents is essential in the prevention of low cardiac output syndrome.

Epstein-Barr virus in nasal T-cell lymphomas (polymorphic reticulosis/midline malignant reticulosis) in western China

Polymorphic reticulosis (PR) or midline malignant reticulosis (MMR) is considered to be malignant, or at least pre-malignant T-cell proliferations of the nose or midline area. Recent reports of small series of nasal T-cell lymphomas have shown a strong association with Epstein-Barr virus (EBV). Furthermore, a peculiar phenotype is described, with expression of CD56 and not of CD3, suggesting a possible origin from natural killer (NK) cells. We have analysed a series of 38 cases of PR/MMR for the presence of EBV by in situ hybridization (ISH) of the EBV-encoded RNAs 1 and 2 (EBER). Twenty cases were tested for expression of EBV-encoded latent membrane protein 1 (LMP-1). Special attention was also paid to the expression of CD3 and the NK cell-related marker CD56. Thirty-two cases (84 per cent) showed positive EBER ISH. In 5 of 20 cases, LMP-1 expression was detected. In three cases, a few scattered cells were positive, and in two cases, LMP-1 was detected in clusters of atypical cells. Most of the neoplasms showed expression of CD3 (89 per cent) and in 27 cases (71 per cent), CD56 was detected. These results are consistent with an aetiopathogenetic role for EBV in most, but not all, cases of PR/MMR. Our findings are less supportive of a major role for LMP-1 in tumour genesis. CD3 expression in most of the cases of PR/MMR underlines the T-cell origin of these neoplasms, often with aberrant expression of CD56.

[Mitochondrial DNA mutation in Leber's hereditary optic neuropathy in China]

Leber's hereditary optic neuropathy (LHON), a typical maternally inherited disease, is caused by a single nucleotide change of G to A at the site of nucleotide 11,788 of mtDNA. We used PCR method to analysis mtDNA from 102 individuals of nineteen pedigrees. The results showed that 67% of the patients (30/45) and 55% (29/53) of the maternal relatives have such a mutation, while no mutation exists in the four normal individuals. The results show that Wallace's mutation is a main cause of LHON in China.