Development of atrophy of the retinal pigment epithelium around disciform scars

BACKGROUND/AIMS

Eyes with burnt out disciform scars secondary to age related macular degeneration (AMD) are regarded as visually stable. The aim of this study is to report the subsequent development of atrophy of the retinal pigment epithelium (RPE) around the scars and discuss the possible basis.

METHODS

20 eyes from 18 patients were observed to develop atrophy around choroidal neovascularisation (CNV). A method of measuring expansion of the atrophy over time is described using the Topcon Imagenet 2000 system. An additional 10 clinicopathological examples were reviewed.

RESULTS

Clinically CNV became surrounded initially by a ring of pallor that progressed to an expanding band of atrophy of the RPE. It developed most rapidly in the first 3 years after CNV became quiescent but then continued to expand slowly to more than three times the size of the scar. Histopathological specimens showed large choroidal vessels entering the scars directly and a reduced number of small choroidal vessels beneath and around the scar

CONCLUSIONS

Disciform scars may become surrounded by an expanding band of atrophy of the RPE, postulated to result from remodelling of the choroidal circulation. The ongoing enlargement of the resulting scotoma may need to be considered when planning management and assessing treatment outcomes.

A comparison of three methods of wound closure following arthroplasty

We carried out a blinded prospective randomised controlled trial comparing 2-octylcyanoacrylate (OCA), subcuticular suture (monocryl) and skin staples for skin closure following total hip and total knee arthroplasty. We included 102 hip replacements and 85 of the knee.

OCA was associated with less wound discharge in the first 24 hours for both the hip and the knee. However, with total knee replacement there was a trend for a more prolonged wound discharge with OCA. With total hip replacement there was no significant difference between the groups for either early or late complications. Closure of the wound with skin staples was significantly faster than with OCA or suture. There was no significant difference in the length of stay in hospital, Hollander wound evaluation score (cosmesis) or patient satisfaction between the groups at six weeks for either hips or knees.

We consider that skin staples are the skin closure of choice for both hip and knee replacements.

Sympathetic genital responses induced by p-chloroamphetamine in anaesthetized female rats

In urethane-anesthetized female rats, a branch of the hypogastric nerve equivalent to the vas deferens nerve in males was shown anatomically and electrophysiologically to supply the uterine horns and we have consequently termed this the uterine nerve. Administration of p-chloroamphetamine i.v. elicited patterned bursting uterine nerve activity responses together with contractions of the uterine horns and musculature of the vaginal wall. These responses are qualitatively similar to ejaculatory responses observed following p-chloroamphetamine administration to anesthetized male rats and the urethrogenital reflex in females, suggesting they represent responses occurring during sexual processes. This response to p-chloroamphetamine was still present after complete transection of the spinal cord at T8. These data indicate that common neurophysiological and pharmacological mechanisms regulate genital reflexes at the lumbosacral spinal level in both the female and the male rat.

Activation by p-chloroamphetamine of the spinal ejaculatory pattern generator in anaesthetized male rats

In urethane-anesthetized male rats, a branch of the hypogastric nerve was shown, anatomically and electrophysiologically, to supply the vas deferens. Recordings from this nerve revealed a low level of tonic activity, which was predominantly efferent motor activity. Administration of p-chloroamphetamine i.v., elicited a rhythmic burst of neuronal activity, coherent with rhythmic pressure increases in the vas deferens and contractions of the bulbospongiosus muscles, which together comprise ejaculation. This response to p-chloroamphetamine was still present after complete transection of the spinal cord at T8-T9. These data indicate that p-chloroamphetamine is capable of activating the spinal neuronal circuits that generate the pattern of autonomic and somatic responses similar to those of sexual climax. Furthermore based on the best documented action of p-chloroamphetamine, the results suggest that the excitability of the pattern generator is regulated by serotonergic, dopaminergic or noradrenergic receptors in the lumbosacral spinal cord. We conclude this animal model will enable robust studies of the pharmacology and physiology of central neural mechanisms involved in ejaculation and sexual climax.

Long QT syndrome presenting as epileptic seizures in an adult

A 50 year old woman with a previous diagnosis of epilepsy presented to the emergency department with a generalised seizure. Her admission ECG showed QT prolongation secondary to bradycardia and a subsequent seizure in the department demonstrated that these events were secondary to cerebral hypoperfusion during episodes of torsades de pointes. This case illustrates how long QT syndrome can masquerade convincingly as epilepsy, delaying treatment and exposing the patient to a high risk of sudden cardiac death. Careful ECG analysis is recommended for all patients presenting with seizures.

[Isolation and expression profiling of the Pto-like gene SsPto from Solanum surattense]

A novel Pto-like gene (designated as SsPto) is cloned from yellow-fruit nightshade (Solanum surattense). The full-length cDNA of SsPto is 1331 bp long with an open reading frame of 960 bp encoding a polypeptide of 320 amino acid residues. The deduced SsPto protein has a calculated molecular weight of 36.21 kDa with an isoelectric point of 6.18. Multiple sequence alignment shows that SsPto protein shares 71.4% and 71.6% identities to Pto proteins from Lycopersicon pimpinellifolium and L. hirsutum respectively. Genomic Southern blot analysis indicates the presence of a small family of SsPto in the S. surattense genome. SsPto is found to be constitutively expressed in the S. surattense plant with the highest expression in stems. However, under induction by TMV for 6 days, SsPto expresses the highest in roots. Further expression analysis reveals that the signaling components of defense/stress pathways, such as methyl jasmonate (MeJA), salicylic acid (SA), gibberellic acid (GA3) and hydrogen peroxide (H2O2), up-regulate the SsPto transcript levels over the control. Cold treatment, nevertheless, has no significant effect on SsPto expression whereas SsPto expression is down-regulated by dark treatment. Our findings suggest that this novel stress- and pathogen-inducible SsPto from S. surattense may participate not only in the defense/stress responsive pathways, but also in diverse processes of plant's growth and development.

[Identification and characterization of differentially expressed ESTs of Gossypium barbadense infected by Verticillium dahliae with suppression subtractive hybridization]

Cotton wilt defense reaction is a complicated continuous process and involves a battery of genes. In this study, we adopted suppression subtractive hybridization (SSH) technique to isolate differentially expressed ESTs from Gossypium barbadense variety 7124 during Verticillium wilt defense process. An array of 1165 clones from the subtractive library has been screened with reverse northern blotting, of which 131 ESTs were considered as over-expressed and 16 ESTs were down-regulated. Sequence analysis and blast search showed that 83 ESTs were homologous to 45 unique sequences in the databases. Among all these differentially expressed ESTs, at least three kinds of genes were characterized. The majority of ESTs with deduced identity to aerobic metabolism enzymes strongly expressed in the infection process. Likewise, ESTs similar to those reported for pathogen-related protein genes were also picked out in this study. These ESTs in combination with other kinase-like genes and a defensin-like EST constituted an assembly of genes responded during pathogens' infection. These results imply that sea-island cotton undergoes strong oxidative stress and results in a series of defense responses when attacked by V. dahliae. To our knowledge, this is the first report on the isolation of global ESTs during sea-island cotton defense reaction.

Type I bone morphogenetic protein receptors are expressed on cerebellar granular neurons and a constitutively active form of the type IA receptor induces cerebellar abnormalities

Cerebellar granular neurons are the most abundant neuronal type in the CNS. Their number and experimental accessibility have made these neurons a valuable model for investigating mechanisms of cell proliferation and differentiation in the CNS. Proliferation of granular neurons is regulated, at least in part, by the secreted protein Sonic Hedgehog, whereas induction and differentiation both appear to be controlled by bone morphogenetic protein (BMP) signaling. Given the role of BMPs in granular cell differentiation, we postulated that BMP receptors (BMPRs) would be expressed on cerebellar granular neurons and that signaling through these receptors is required for normal differentiation. We found that both BMPRIA and BMPRIB are expressed on granular neuron precursors and on mature granular neurons in the developing cerebellum. To determine if these receptors are sufficient for granular cell induction and/or differentiation in vivo, we introduced a constitutively active BMPRIA construct into the developing cerebellum. The resulting cerebelli showed a simplified folial pattern and ectopic collections of small cells located deep in the cerebellar white matter. Phenotypic analysis demonstrated that the ectopic cells are granular neurons. From these data we suggest that signaling through the type I BMPRs occurs during normal cerebellar development and ectopic activation of this pathway affects normal granular neuron development. Furthermore, the similarity of the cerebellar anomalies arising from perturbed BMPR signaling to human cerebellar malformations suggests that dysregulation of BMP signaling may play a pathogenic role in some human cerebellar abnormalities.

Role of eicosanoids in prostate cancer progression

Metabolism of arachidonic acid through cyclooxygenase, lipoxygenase, or P450 epoxygenase pathways leads to the formation of various bioactive eicosanoids. In this review, we discuss alterations in expression pattern of eicosanoid-generating enzymes found during prostate tumor progression and expound upon their involvement in tumor cell proliferation, apoptosis, motility, and tumor angiogenesis. The expression of cyclooxygenase-2, 12-lipoxygenase, and 15-lipoxygenase-1 are up-regulated during prostate cancer progression. It has been demonstrated that inhibitors of cyclooxygenase-2, 5-lipoxygenase and 12-lipoxygenase cause tumor cell apoptosis, reduce tumor cell motility and invasiveness, or decrease tumor angiogenesis and growth. The eicosanoid product of 12-lipoxygenase, 12(S)-hydroeicosatetraenoic acid, is found to activate Erkl/2 kinases in LNCaP cells and PKCalpha in rat prostate AT2.1 tumor cells. Overexpression of 12-lipoxygenase and 15-lipoxygenase-1 in prostate cancer cells stimulate prostate tumor angiogenesis and growth, suggesting a facilitative role for 12-lipoxygenase and 15-lipoxygenase-1 in prostate tumor progression. The expression of 15-lipoxygenase-2 is found frequently to be lost during the initiation and progression of prostate tumors. 15(S)-hydroxyeicosatetraenoic acid, the product of 15-lipoxygenase-2, inhibits proliferation and causes apoptosis in human prostate cancer cells, suggesting an inhibitory role for 15-lipoxygenase-2 in prostate tumor progression. The regulation of prostate cancer progression by eicosanoids, in either positive or negative ways, provides an exciting possibility for management of this disease.

The clinical utility of nuclear medicine imaging for the detection of occult gastrointestinal haemorrhage

Acute gastrointestinal bleeding is often intermittent and the bleeding source may be difficult to locate, resulting in delay of potentially life-saving treatment. The aim of this study was to determine the clinical utility of 99mTc labelled red blood cell imaging and [99mTc]pertechnetate (Meckel's scan) imaging in a series of 137 patients admitted over a 5 year period to hospital for management of acute gastrointestinal bleeding. Of the 137 patients, 70 had positive 99mTc red blood cell studies. Eleven of 24 patients who had imaging performed beyond 3 h had positive scans that would otherwise have been missed. Only 47 patients had a definite final diagnosis at the time of hospital discharge, of which six were negative on 99mTc red blood cell imaging. The correct site of bleeding was localized in seven of 21 patients with foregut bleeding, and 15 of 20 patients with colonic bleeding. Endoscopy yielded a diagnosis in 13 of the 47 patients (28%). Eleven patients had Meckel's scans but all were negative. Angiography was diagnostic in one of 17 patients studied. 99mTc red blood cell imaging is a useful test in the management of acute gastrointestinal bleeding. Imaging beyond 3 h may further improve the bleeding detection rate. This test, however, may be an unreliable means of localization of bleeding, particularly in the foregut.

Wnt-1 promotes neuronal differentiation and inhibits gliogenesis in P19 cells

Wnt-1, the vertebrate counterpart of the Drosophila wingless gene, plays an important role in the early morphogenesis of neural tissues. In this report, we have shown that overexpression of Wnt-1 can direct embryonic carcinoma P19 cells to differentiate into neuron-like cells in the absence of retinoic acid. Immunocytochemistry showed that these cells expressed neuronal markers, such as the neurofilament (NF) and microtubule-associated protein 2 (MAP2), but failed to express the glial cell marker, glial fibrillary acidic protein (GFAP). RT-PCR revealed that two basic helix-loop-helix (bHLH) genes, Mash-1 and Ngn-1, were up-regulated during the differentiation stage of Wnt-1-overexpressing P19 cells. These results suggest that the Wnt-1 gene promotes neuronal differentiation and inhibits gliogenesis during the neural differentiation of P19 cells, and that neural bHLH genes might be involved in this process.

A new high sensitivity thermoluminescent phosphor with low residual signal and good stability to heat treatment: LiF:Mg,Cu,Na,Si

The preliminary investigations are reported on the characteristics of a new, high-sensitivity thermoluminescence phosphor material (LiF:Mg,Cu,Na,Si) prepared in this laboratory. The main dosimetric peak of this phosphor occurs at 197 degrees C at a heating rate of 1 degrees C.s(-1). The glow curve shape shows minimal differences and sensitivity remains stable when annealed in the range from 250 to 280 degrees C for 10 min. Its TL sensitivity to gamma radiation is about 30 times higher than that of TLD-100 with a residual signal 0.2% following a 260 degrees C readout at a heating rate of 15 degrees C.s(-1). This negligible residual signal renders LiF:Mg,Cu,Na,Si usable in unannealed form. Its TL response at both 260 degrees C and 280 degrees C are reproducible within a coefficient of variation of 2% over ten re-use cycles without systematic decrease. It retains the main advantages of LiF:Mg,Cu,P phosphor, and has a lower residual signal and a better stability to heat treatment.

New advances in LiF:Mg,Cu,P TLDs (GR-200A)

In order to volume-produce LiF:Mg,Cu,P TLDs, increase the repeatability of preparation technology and further improve the features of TLDs, especially the moisture resistant property and the accuracy in ultra-low dose, the prescription and preparation techniques have been investigated further in recent years. The main features of GR-200A have been improved dramatically by adding a chemical additive and adopting a particular preparation technology. Recent improvements are presented including prescription, preparation technology, TL sensitivity, signal-to-noise rate, detection threshold, residual signal, the moisture resistant property and the uncertainty in low dose measurements. The sensitivity of GR-200A has been increased to 65 times as high as TLD-100 from the original 29 times. The residual signal has been decreased to less than 1% from the original of about 2.5% following 240 degrees C readout. The detection threshold decreases and the signal-to-noise ratio increases. The uncertainty in low dose measurements is reduced significantly. The resistance to humidity has been improved remarkably. The preparation technology to volume-produce GR-200A is stable.

Influence of readout parameters on TL response, re-usability and residual signal in LiF:Mg,Cu,P

It has recently been recommended that heating rates do not exceed 10 K.s(-1) and that the maximum temperature of readout should not exceed 265 degrees C for LiF:Mg,Cu,P. In some cases, a decrease of sensitivity in this material in the first of several re-use cycles had been reported. Influence of heating rates up to 30 K.s(-1), duration time up to 40s and maximum readout temperatures up to 270 degrees C on TL response, re-usability and residual signal was investigated. It was found that the maximum readout temperatures above 240 degrees C may lead to the thermoluminscent response decrease in the first several re-use cycles. The readout parameters can be optimised to minimise the residual signal (less than 0.4%) and to retain a constant sensitivity at the same time at high heating rates up to 30 K.s(-1) in a short time (less than 1 min per TL chip) without the necessity of heating above 240 degrees C. A concept of 'efficient residual signal' was put forward to quantify more accurately the real residual signal which affects the precision of the next measurement.

Comparative study of trapping parameters and repeatability of LiF:Mg,Cu,P (GR-200A) from different production batches

Distinct differences in repeatability between two different production batches had been observed. The results are presented of an investigation into the change of sensitivity of LiF:Mg,Cu,P originating from 7 different production batches prepared during 1994 to 2000 after repeated usage. Computerised glow curve analysis has been used to determine the trapping parameters of these thermoluminescent materials. The sensitivity in LiF:Mg,Cu,P for all investigated batches remains stable after repeated usage. The maxima of glow peaks 2 to 4 are found at the same temperature within very small limits. The activation energy and frequency of glow peaks 2 to 4 vary little from batch to batch. For all investigated peaks, no correlation has been found between glow sensitivity and trapping parameters. The peak areas of glow peaks 3 and 4 originating from 4 batches prepared during 1996 to 2000 are significantly larger than that of the other three batches. The GR-200A LiF:Mg,Cu,P has been improved dramatically in recent years.

Isolation and characterization of a novel cDNA, UBAP1, derived from the tumor suppressor locus in human chromosome 9p21-22

PURPOSE

To clone the putative tumor suppressor gene(s) in a refined region at 9p21-22 undergoing loss of heterozygosity in nasopharyngeal carcinoma (NPC).

METHODS

We systematically screened the expression patterns of 25 novel ESTs (expressed sequence tags) in a minimal common deleted region of 9p21-22 in NPC. One of these ESTs was found down-regulated in NPC. Subsequently, the corresponding gene sequence of this EST was established by cDNA cloning and RACE (rapid amplification of cDNA end) procedures. Furthermore, a mouse homologue of this gene was identified. The expression of this gene was examined using Northern blot or reverse transcription-polymerase chain reaction (RT-PCR) in various human and mouse tissues. A limited screen for mutation of coding sequence of this novel human gene was undertaken using RT-PCR and direct sequencing analysis.

RESULTS

A novel gene was cloned. This gene is a new member of the UBA domain family, so we named it UBAPI for ubiquitin-associated protein 1 (HUGO Gene Nomenclature Committee-approved symbol). Northern blot and RT-PCR analysis demonstrate a ubiquitous pattern of gene expression in human and mouse tissues. The direct sequencing analysis of the coding region of hUBAP1 following RT-PCR failed to reveal any mutations in a preliminary screen of NPC cell line HNE1 and primary nasopharyngeal carcinoma samples.

CONCLUSIONS

We cloned a novel gene UBAPI, which is highly conserved between human and mouse. Clearly, as a novel member of UBA domain protein family and taking its map location into account, a more extensive analysis is essential to establish whether subtle mutations are present in nasopharyngeal carcinomas.