Ultrastructural characteristics of the sporogenesis of genus Myxobolus infecting some Nile fishes in Egypt

This study presents the ultrastructural characteristics of sporogenesis in the genus Myxobolus which infects four economically important Egyptian fishes: Oreochromis niloticus niloticus, Barbus bynni, Labeo niloticus and Hydrocynus forskalii, specimens of which were collected at Giza city. Although the cysts were observed in different organs, the pattern of sporogenesis was the same. Moreover, the sporogenesis found in the present study followed the usual pattern valid for most of the myxosporean genera studied.     

Alzheimer's disease associated with mutations in presenilin 2 is rare and variably penetrant

Missense mutations in the presenilin 2 (PS-2) gene on chromosome 1 were sought by direct nucleotide sequence analysis of the open reading frame of 60 pedigrees with familial Alzheimer's disease (FAD). In the majority of these pedigrees, PS-1 and beta-amyloid precursor protein (beta APP) gene mutations had been excluded. While no additional PS-2 pathogenic mutations were detected, four silent nucleotide substitutions and alternative splicing of nucleotides 1338-1340 (Glu325) were observed. Analysis of additional members of a pedigree known to segregate a Met239Val mutation in PS-2 revealed that the age of onset of symptoms is highly variable (range 45-88 years). This variability is not attributable to differences in ApoE genotypes. These results suggest (i) that, in contrast to mutations in PS-1, mutations in PS-2 are a relatively rare cause of FAD; (ii) that other genetic or environmental factor modify the AD phenotype associated with PS-2 mutations; and (iii) that still other FAD susceptibility genes remain to be identified.      

The Kallmann syndrome gene product expressed in COS cells is cleaved on the cell surface to yield a diffusible component

Kallmann syndrome is characterized by hypogonadotropic hypogonadism and anosmia and caused by a defect of migration and targeting of gonadotropin-releasing hormone-secreting neurons and olfactory axons during embryonic development. We previously cloned the gene responsible for the X-linked form of the disease encoding a 680 amino acid protein, KAL, which displays the unusual combination of a protease inhibitor domain with fibronectin type III repeats. Previous expression studies by northern blot and RNA in situ hybridization in human and chick indicated that the gene is expressed at very low levels in the olfactory bulb during development. Therefore, low abundance of the protein has hampered a detailed biochemical characterization. By overexpressing both the human and chick KAL cDNAs in eukaryotic cells, we now provide evidence that KAL is a glycosylated peripheral membrane protein with an apparent molecular weight of approximately 100 kDa. We show that this 100 kDa protein is proteolytically processed on the cell membrane to yield a 45 kDa diffusible component, which is detectable with an antisera against the C-terminal part of the protein and binds tightly to cell surfaces. These data provide a first step toward understanding KAL function in neuronal interactions and neurite extension in the olfactory bulb and suggest that KAL might be a diffusible chemoattractant molecule for olfactory axons.      

Serum luteinizing hormone,follicle-stimulating hormone and oestradiol pattern in women undergoing pituitary suppression with different gonadotrophin-releasing hormone analogue protocols for assisted reproduction

Gonadotrophin-releasing hormone analogues (GnRH-a) are used widely in controlled ovarian stimulation (COS) cycles for assisted reproduction. At present, there is great debate about the influence of exogenous hormone activity on the hypothalamus–pituitary axis following pituitary desensitization. The objective of this comparative study was to investigate the pattern of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and oestradiol in women undergoing ovarian stimulation with different GnRH-a preparations. We retrospectively analysed 201 women, aged between 27 and 43 years, who were referred consecutively to our infertility clinic between January 2002 and January 2003. All women had no endocrinopathies or occult ovarian failure as assessed by day-3 hormone profile. Women were enrolled in one of the following COS protocols: depot triptorelin long protocol (n?=?38), buserelin long protocol (n?=?101) or buserelin short protocol (n?=?62). Recombinant FSH was used to induce ovulation. Treatment was monitored by transvaginal ultrasound scan and serum measurement of FSH, LH and oestradiol. Among the women initially included, 30 had cancelled cycles due to poor ovarian response. Serum LH levels were significantly higher in the short-protocol group compared with the long-protocol groups (p?<?0.001). The number of follicles, oocyte yield, number of grade-I embryos and fertilization rate were significantly lower in the short-protocol group than in the long-protocol groups. These findings showed that LH concentrations are significantly higher in women undergoing reversible medical hypophysectomy with a GnRH-a short protocol than in women treated with a long protocol. The hypothesis of an LH ceiling is confirmed.     

A homoallelic FECH mutation in a patient with both erythropoietic protoporphyria and palmar keratoderma

Background Erythropoietic protoporphyria (EPP) is a hereditary disorder caused by the deficiency of ferrochelatase (FECH) in the haem biosynthetic pathway. In the majority of families, EPP is transmitted as a pseudodominant trait. Autosomal recessive form of EPP is found in only about 3% of the families. Objectives In this study, we describe a 6‐year‐old boy who suffered from both EPP and palmar keratoderma. Methods and Results A novel homoallelic missense mutation (p.Ser318Tyr) was identified in the FECH gene. In addition, a region of homozygosity of approximately 6.8 Mb was observed in chromosome 18 of the patient by both microsatellite and SNP array. The parents of the patient, both of Palestinian (Jordanian) origin, were heterozygous for the S318Y mutation, although no history of consanguinity was known. Microsatellite genotyping identified a partial haplotype from each parent that corresponds to the region of homozygosity in the patient. Assuming S318Y is a founder mutation, the number of generations separating the two parents from their common ancestor from whom they inherited S318Y was estimated as 21.7 (95% CI 3.42–69.7). Conclusion EPP was therefore inherited as an autosomal recessive trait in the family. This study confirms the association between palmar keratoderma and autosomal recessive EPP.     

Bacteria etiological agents causing respiratory tract infections in children and their resistance patterns to a panel of ten antibiotics

ObjectiveTo study the bacteria etiological agents of respiratory tract infection among 280 school children in South East Nigeria, and to determine their antimicrobial resistance patterns to a panel of ten antibiotics.MethodsThroat swabs (280) were collected from students in four boarding schools located in Enugu and Onitsha metropolis. Standard microbiological procedures were used to screen these swabs to determine the prevalence of respiratory pathogens while the disc diffusion test was used to determine the antimicrobial resistance patterns of the recovered isolates.ResultsOf the 280 samples screened, 57.1% were positive. Haemophilus influenzae was the most prevalent (16.1%), followed by Streptococcus pyogenes (13.9%), Klebsiella pneumoniae (12.5%), Streptococcus pneumoniae (6.8%), Staphylococcus aureus (5.4%) and Corynebacterium diphtheriae (2.5%). More isolates were recovered in the two male schools investigated. However, there was no significant difference in the overall prevalence of isolates according to sex or school location of the subjects. Greater number of isolates (56%) was recovered from those aged 11–14 years. This was statistically significant (P<0.05), compared to the other two age groups (15–18 years and 19–23 years). The pattern of resistance varied according to the bacteria species. There were multi-resistant isolates. Since these students stand the risk of contracting respiratory tract infection particularly from reservoirs among them, there is need to increase surveillance and develop better strategies to curb the increasing prevalence of respiratory tract infection in this and other similar regions of Africa.ConclusionsThe spectrum of bacteria causing respiratory tract infection is still wide in Nigeria. Many isolates showed appreciable levels of antibiotic resistance apparently due to antibiotic abuse. Development of new strategies to curb this increasing prevalence of respiratory tract infection is warranted.     

Mice with an aspartylglucosaminuria mutation similar to humans replicate the pathophysiology in patients

Aspartyglucosaminuria (AGU) is a lysosomal storage disease with autosomal recessive inheritance that is caused by deficient activity of aspartylglucosaminidase (AGA), a lysosomal enzyme belonging to the newly described enzyme family of N-terminal hydrolases. An AGU mouse model was generated by targeted disruption of the AGA gene designed to mimic closely one human disease mutation. These homozygous mutant mice have no detectable AGA activity and excrete aspartylglucosamine in their urine. Analogously to the human disease, the affected homozygous animals showed storage in lysosomes in all analyzed tissues, including the brain, liver, kidney and skin, and lysosomal storage was already detected in fetuses at 19 days gestation. Electron microscopic studies of brain tissue samples demonstrated lysosomal storage vacuoles in the neurons and glia of the neocortical and cortical regions. Magnetic resonance images (MRI) facilitating monitoring of the brains of living animals indicated cerebral atrophy and hypointensity of the deep gray matter structures of brain-findings similar to those observed in human patients. AGU mice are fertile, and up to 11 months of age their movement and behavior do not differ from their age-matched littermates. However, in the Morris water maze test, a slow worsening of performance could be seen with age. The phenotype mimics well AGU in humans, the patients characteristically showing only slowly progressive mental retardation and relatively mild skeletal abnormalities.      

Glycoprotein IIb and IIIa retention on fibrinogen-coated surfaces after lysis of adherent platelets

The platelet-membrane glycoprotein IIb-IIIa (GPIIb-IIIa) complex is essential for platelet aggregation and is involved in the attachment of platelets to thrombogenic surfaces. This study shows the retention of GPIIb and GPIIIa on immobilized fibrinogen after Triton X-100 (Sigma Chemical Co, St Louis, MO) lysis of adherent platelets. Glycoproteins were detected using subunit specific monoclonal antibodies in a modified enzyme-linked immunosorbent assay procedure. GPIIb-IIIa retention was judged to be specific relative to GPIb recovery, and was modulated by platelet activation. Platelet exposure to adenosine diphosphate or thrombin, but not A23187 or chymotrypsin, markedly enhanced GPIIb and GPIIIa recovery relative to that observed with unstimulated platelets, or prostaglandin E1-treated platelets. Moreover, lysis of adherent platelets in the presence of 10 mmol/L EDTA, under conditions promoting GPIIb-IIIa complex dissociation (pH 8.1, 60 minutes, 37 degrees C), had no effect on GPIIb or GPIIIa subunit recovery. Platelet activation with Zn+2 also enhanced GPIIb and GPIIIa recovery on fibrinogen-coated surfaces over that observed with unstimulated platelets, but GPIIb and IIIa retention was EDTA sensitive. This correlated with the EDTA-reversible nature of Zn+2- activated platelet adhesion to fibrinogen-coated surfaces. The data (1) show that platelet adhesion to fibrinogen is accompanied by the induction of high-affinity interactions between GPIIb-IIIa and immobilized fibrinogen that are EDTA-resistant and enhanced by platelet activation with some but not all agonists, and (2) implicate these interactions in stabilizing platelet contacts with fibrinogen-coated surfaces.     

16例脑结核瘤抗结核治疗系列观察

目的:报告16例颅内结核瘤患者的临床、影像学表现及抗结核治疗的结果.设计:本文共纳入苏丹Khartoun市全国神经系统疾病中心连续观察的16例脑结核瘤患者.诊断则依据其临床、头颅影像学特征及对抗结核治疗有效等方面.本组中共有7例具有脑组织或脑外组织的病理组织学资料.结果与结论:本组病例最常见的临床表现是头痛(100%)、全身性抽搐(68.7%)及偏瘫(56.2%).头颅横断面电子计算机体层摄影(CT)/核磁共振成像(MRI)显示单个或多个明显增强的病变及病灶周围水肿.经抗结核治疗后,多数存活患者(13/15)病变完全吸收.病变部分吸收与就诊延迟、颅内多个大病灶及晚期粟粒性结核病有关.我们主张对颅内结核瘤,即使是拟诊病例,应早期经验性试用抗结核治疗,尤其在结核病高发地区.