Function of Arl4aa in the Initiation of Hematopoiesis in Zebrafish by Maintaining Golgi Complex Integrity in Hemogenic Endothelium.

ADP-ribosylation factor-like 4aa (Arl4aa) is a member of the ADP-ribosylation factor family. It is expressed in hematopoietic tissue during embryonic development, but its function was unknown. Zebrafish arl4aa is preferentially expressed in the ventral wall of the dorsal aorta (VDA) at 24 and 36 hpf and in caudal hematopoietic tissue at 48 hpf. Morpholino knockdown and transcription activator-like effector nuclease (TALEN) knockout of arl4aa significantly reduced expression of genes associated with definitive hematopoietic stem cells (HSCs). Golgi complex integrity in VDA was disrupted as shown by transmission electron microscopy and immunostaining of Golgi membrane Giantin. Mechanistically, arl4aa knockdown reduced Notch signaling in the VDA and its target gene expression. Protein expression of NICD was also reduced. Effects of arl4aa knockdown on definitive hematopoiesis could be restored by NICD expression. This study identified arl4aa as a factor regulating initiation of definitive HSCs by maintaining the integrity of Golgi complex and, secondarily, maturation of the Notch receptor.

Effects of sperm DNA damage on the levels of RAD51 and p53 proteins in zygotes and 2-cell embryos sired by golden hamsters without the major accessory sex glands.

We previously reported that the male accessory sex gland (ASG) secretion is the main source of antioxidants to safeguard sperm genomic integrity and functional competence. Removal of all ASGs in the golden hamster can reduce male fertility by increasing embryo wastage. This study aims to investigate whether the oxidative DNA-damaged sperm from hamsters without all ASGs (TX) could successfully fertilize oocytes and to qualify the status of DNA repair by the expression of RAD51 and p53 proteins. Here we demonstrated a significantly higher DNA-base adduct formation (8-hydroxy-2'-deoxyguanosine) in sperm from TX males than those from sham-operated males. Comet assays demonstrated that all female pronuclei in both zygotes were intact, but single- and double-strand DNA damage was found in decondensed sperm in TX males only. DNA damage could also be detected in both nuclei of the TX 2-cell embryos. RAD51, a DNA repair enzyme, was found to be evenly distributed in the cytoplasm and nuclei in oocytes/zygotes, while at the 2-cell stage, a strong expression of p53 protein and a larger clear perinuclear area without RAD51 expression were found in TX embryos. In conclusion, we demonstrated for the first time DNA damage in decondensed sperm of zygotes and blastomeres of 2-cell stage embryos sired by TX males, resulting in the activation of DNA repair. Sperm DNA damage could induce the increase in p53 expression and the reduction of RAD51 expression in the TX 2-cell stage embryos.

In vitro-matured rat oocytes have low mitochondrial deoxyribonucleic acid and adenosine triphosphate contents and have abnormal mitochondrial redistribution.

OBJECTIVE: To study the development and function of mitochondria in in vitro-matured rat oocytes derived from follicles of different sizes. DESIGN: Experimental animal study. SETTING: Department of Anatomy at the University of Hong Kong. ANIMAL(S): Immature female Sprague-Dawley rats that were 25 days of age. INTERVENTION(S): Immature oocytes were collected from rat ovarian follicles of different sizes and were induced to mature in vitro. MAIN OUTCOME MEASURE(S): The number of copies of mitochondrial DNA, mitochondrial activity, adenosine triphosphate content of matured oocytes, and rates of fertilization and blastulation were determined. RESULT(S): The mitochondrial DNA copy number of oocytes increased linearly with the diameter of antral follicles. The mitochondrial DNA copy number, adenosine triphosphate content, and proportion of oocytes with peripheral distribution of mitochondria in in vitro-matured oocytes from small antral follicles were significantly lower than those from preovulatory follicles and in vivo-matured oocytes. Compared with in vitro-matured oocytes from small antral follicles, those from preovulatory follicles and in vivo-matured oocytes also had significantly better fertilization potential and higher blastulation rate. CONCLUSION(S): The inferior developmental potential of in vitro-matured oocytes may be attributed partly to a reduced number of mitochondria, resulting in insufficient production of adenosine triphosphate for required developmental events.

Extradural haematoma: a rare, but fatal complication of pyknodysostosis.

We report a 4-year-old girl with pyknodysostosis who suffered a skull fracture and epidural haematoma following a minor fall. Craniotomy was needed to evacuate the haematoma and prevent mortality. Extradural haematoma in this group of patients is rare, ours being the second case reported in literature.

Alignment of dispersed multiwalled carbon nanotubes in low strength AC electrical fields.

The possibilities to use electricity as a tool to induce alignment of multiwall carbon nanotubes suspended in water with help of a non-ionic surfactant have been investigated. Several different experiments were made using various field strengths and frequencies of 15-140 V/cm and 0.1-500 Hz respectively. The experiments were recorded by filming the processes through a reflected light microscope. Each movie is between 15-45 seconds long and is adequate to estimate orientation rates and alignment directions. It was observed that the alignment rate increased with increasing field strength and that the system is less sensitive at lower frequencies. Both field strength and frequency can be used to control the speed and degree of orientation. At low frequencies, the suspension is forced to oscillate in a pumping fashion between the electrodes. The nanotubes are forced to align with the fluid streamlines rather than with the field lines. At higher frequencies, the oscillation ceases. Alignment rate increases with increasing field strengths. The MWNTs are fully aligned in less than 1 s for an electrical field > or = 70 V/cm and frequency > 20 Hz. A similar experiment was carried out for a non-ideal MWNT/H2O dispersion system. It was observed that the MWNTs aligned in the same fashion as before but after a few minutes a transition occurred. The MWNTs moved quickly towards each other and a network consisting of mainly aligned MWNTs was created. The MWNT movement slowed down after the network had branched out to connect the electrodes. The alignment of CNTs in an applied electrical field seems to be an efficient, quick, and cheap method with many advantages. The method opens doors to many interesting and exciting possibilities for production of novel materials with unique properties. Both alignment of separated MWNTs and the creation of aligned MWNTs in networks are of interest from an engineering point of view.

Should airguns be banned?

In this article, we express concerns regarding the availability of airguns, the injuries that they cause and their abuse as weapons of assault. We wish to stimulate debate on this topic and report a 5-year retrospective analysis of all airgun injuries to the head and neck, presenting to Alder Hey Children's Hospital, Liverpool, from June 1998 to June 2003. We identified 16 patients who suffered such injuries with ages ranging from 5 to 15 years. The majority of cases were violent assaults, which is not in accordance with previous published reports. All of these occurred in public places outside the home. Most incidents occurred through the spring and summer period. Six patients required overnight stay in hospital. Nine patients required operative procedures to remove the airgun pellets. Two patients had serious eye injuries resulting in loss of vision. Two patients had penetrating neck injuries requiring exploration of the wound. The remaining group had either skin-penetrating injuries with lodgement of fragments in subcutaneous tissues or non-skin penetrating injuries. This study highlights serious injuries arising from the abuse of airguns as weapons of assault. Airguns are readily available to people without license. Recent legislation has increased the minimum age at which airguns can be carried in a public place, but we believe that stricter legislation is required to produce a reduction in the number of airgun-related injuries.

Extracranial vascular malformation: value of antenatal and postnatal MRI in management.

We report a case where fetal MRI using a low-field-strength magnet (0.5 T) accurately confirmed a large extracranial vascular malformation, which was suspected on antenatal US. Fetal MRI enabled better counselling of the parents and allowed suitable plans to be made regarding method of delivery and early management of the neonate. To our knowledge this is the first case of an extracranial vascular malformation imaged using fetal MRI.

Spontaneous resolution of acute obstructive hydrocephalus in the neonate.

Spontaneous resolution of acute hydrocephalus without aspiration of cerebral fluid is rare. In a neonate born at full term this has only been reported once before. We report on one further case that was caused by intraventricular haemorrhage (IVH). The probable mechanism is resolution of the acute haemorrhage in the region of the aqueduct, resulting in resolution of the hydrocephalus itself. The importance of considering conservative management of acute hydrocephalus in the clinically stable neonate is emphasised.

Hemispherectomy for intractable seizures: a further modification and early experience.

Hemispherectomy is well recognized as an effective treatment for some types of intractable epilepsy, but the procedure is also known to be associated with significant late complications. A number of modifications to the original operation have been developed to try and minimize such late complications. These are reviewed and a further modification is described using a Zenoderm graft to isolate the hemispherectomy cavity from the remaining CSF pathways. We present our early experience with this new modification in seven patients with intractable epilepsy.

The bactericidal activity of magainins against Pseudomonas aeruginosa and Enterococcus faecium.

The antimicrobial activities of two synthetic magainins, MSI 94 and MSI 93, were investigated in vitro against 20 clinical isolates each of Pseudomonas aeruginosa and Enterococcus faecium. The ranges of the MICs of both agents were 6.25-50 mg/L for P. aeruginosa and 3.13-12.5 mg/L for E. faecium. In time-kill studies, the magainins demonstrated rapid, concentration-dependent bactericidal activity against selected isolates of both species. This bactericidal effect was inoculum-dependent for P. aeruginosa in both the logarithmic and stationary phases of growth. Bacterial regrowth was regularly observed after 24 h of incubation in the time-kill studies; this was due to loss of antimicrobial activity during overnight incubation rather than to the development of resistance. More rapid and sustained bactericidal activity was noted when the magainins were combined with either silver nitrate (AgNO3) or gentamicin against P. aeruginosa and with gentamicin against E. faecium. Neither agent produced a post-antibiotic effect on P. aeruginosa.

Necrotizing enterocolitis complicating the management of posthemorrhagic hydrocephalus.

The case notes of all newborn infants with posthemorrhagic hydrocephalus (PHH) operated over the past 10 years at our institution were reviewed to establish the incidence and the effect of necrotizing enterocolitis (NEC) on morbidity and mortality following cerebrospinal fluid (CSF) shunting. Thirteen neonates had both PHH and NEC (group A); 7 of these patients were initially treated by ventriculoatrial (VA) shunt and six by ventriculoperitoneal (VP) shunt. Seventy-five patients had PHH alone (group B); all were treated by VP shunt. Eight patients in group A required an abdominal operation for NEC. The two groups were comparable for birth weight, gestational age, and other complications of prematurity. Episodes of shunt malfunction (infection and/or obstruction) and deaths occurring within 12 months from shunt insertion, in the two groups were compared. Shunt malfunction was more frequent in group A (72%) than in group B (27%) (P < .001). Shunt infection was observed in 39% of group A patients versus 14% in group B (P = .03). Distal shunt obstructions occurred in 28% of group A patients and only 3% of group B patients (P = .001). There were more deaths in group A (62% v 9%; P < .001). Thirty-one percent of group A patients and 4% of group B patients died following shunt complications (P = .006). In group A, there was no significant difference in mortality and shunt malfunction between patients with VA or VP shunts. The method of treatment and the stage of NEC did not influence morbidity and mortality after internal drainage for PHH.(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of recurrence in pituitary tumours: a flow cytometric study using in vivo bromodeoxyuridine.

Although most pituitary tumours are regarded as benign, there is a significant risk of local recurrence and a few are frankly malignant. The prediction of clinically aggressive behaviour by histopathological means is inadequate and the selection of patients for postoperative radiotherapy has often been empirical. The flow cytometric analysis of the DNA content of certain intracranial tumours has suggested a correlation between a high proliferative index and a tendency to recur. The in vivo administration of bromodeoxyuridine (BUdR) yields a reliable and accurate S-phase labelling index and evaluation by flow cytometry allows a much greater and therefore more representative number of cells to be examined. We report our results for the flow cytometric evaluation of the S-phase fraction in a group of 11 human pituitary tumours following the preoperative administration of BUdR and discuss the correlation between high values of S-phase fraction and clinically aggressive behaviour. Initial results suggest a correlation between radiological evidence of tumour invasion and an S-phase greater than 2%.

Paediatric neurosurgery.

Surgical disorders of the central nervous system of children differ significantly from those of adults. The management of these disorders requires an integrated multidisciplinary practice of paediatric specialists in an appropriate paediatric environment. An increasing number of neurosurgeons are now restricting themselves to this field resulting in the more effective diagnosis and treatment of children with neurosurgical disorders.

Dupuytren's contracture. Surgical principles, nursing implications.

Successful Dupuytren's surgery requires the cooperation of the patient, the surgeon, and the therapist. Cooperation of the patient is enhanced by nursing care. Preoperative and postoperative teaching by the nurse also contribute to positive outcomes. The type of incision or surgery performed does not affect the time of recovery if the diseased tissue is removed and there are no postoperative complications.

Benign intrinsic tectal "tumors" in children.

A specific group of intrinsic dorsal midbrain tumors was identified in six children by computerized tomography (CT) and magnetic resonance (MR) imaging. Each patient presented with raised intracranial pressure as a result of hydrocephalus due to obstruction of the sylvian aqueduct. No patient had brain-stem signs referable to the tectal tumor initially or subsequently. All six children underwent cerebrospinal fluid (CSF) diversionary procedures. The radiological features were consistent and specific, with all patients showing tectal calcification or primary increased attenuation of the tectal plate on CT scans. In addition, lack of contrast enhancement was noted initially in four patients and eventually in all six patients. In all patients MR imaging showed a focal tectal tumor distorting the collicular plate with no cystic component and increased signal intensity on T2-weighted images. There has been no evidence of progression in these six patients in the follow-up period ranging from 8 months to 17 years (8 months and 2 1/2, 4 1/2, 8, and 17 years). Diversion of CSF has been the only surgical treatment and no patient underwent deep x-ray therapy. Five patients have had normal intellectual development. In contrast to the majority of previously described periaqueductal and tectal tumors, this group of lesions appeared to be truly benign. The authors suggest that patients presenting with these clinical and radiological features may be managed by CSF diversion, serial examination, and MR imaging.

The prediction of recurrence in meningiomas. A flow cytometric study of paraffin-embedded archival material.

Despite the complete macroscopic excision of meningiomas, there is a significant rate of recurrence approaching 20% at 20 years. The prediction of recurrence by clinical and histopathological means is inadequate. Flow cytometric analysis of deoxyribonucleic acid (DNA) in meningiomas has shown a correlation between a high proliferative index based on tumor cell-cycle stage (%S + %G2/M) and clinically aggressive behavior. Accordingly, the DNA analysis of meningioma tissue may be of value in predicting recurrence of these tumors. To test this hypothesis, the DNA of paraffin-embedded archival tissue from known recurrent meningiomas was compared with an age- and sex-matched nonrecurrent group. Both groups had comparable follow-up periods. Forty patients with total macroscopic removal at the time of surgery were analyzed. The paraffin blocks of these tumors were retrieved and reclassified histologically according to the World Health Organization system. Sections were then taken for flow cytometric study. The DNA analysis showed that the proliferative index of the recurrent group was significantly higher than that of the nonrecurrent group (p less than 0.002), although the histological subtyping of the two groups was similar. These results support the suggestion that flow cytometry may be of value in the prediction of recurrence of histologically benign, macroscopically removed meningiomas.