Management of subretinal macular haemorrhage by direct administration of tissue plasminogen activator

BACKGROUND/AIMS

Recent studies on the treatment of acute subretinal macular haemorrhage have shown that the volume of the clot and the time to evacuation have strong prognostic factors for visual outcome. A novel technique for surgical evacuation of these lesions involves direct injection of tissue plasminogen activator (t-PA) into the haematoma using pars plana vitrectomy. The aim of this study was to evaluate the clinical outcomes of this recently described procedure.

METHODS

17 consecutive patients with subretinal macular haemorrhages caused by age related macular degeneration were enrolled. Patient demographics, acuities, and fluorescein angiograms were obtained for all evaluations. All patients underwent complete three port pars plana vitrectomy to enable direct cannulation of the subretinal space and injection of 48 mug of t-PA, partial fluid-air exchange, 1 hour face up supine positioning postoperatively, followed by upright positioning overnight.

RESULTS

88% of patients within the study had stabilisation or improvement of visual acuity. Nine patients had total clearing of the macular haemorrhage and eight patients had subtotal clearing. Two patients had recurrence of the haemorrhage after the procedure and one patient underwent repair for retinal detachment. Occult lesions demonstrated similar outcomes to classic or predominately classic lesions. Nine patients required no therapy after the study to treat subfoveal neovascularisation.

CONCLUSIONS

This study represents one of the largest case series to date showing that direct injection of subretinal t-PA with air-fluid exchange only and no intraoperative clot lysis period can have favourable results.

Unilateral ocular myasthenia gravis in an acute medical take: is a Tensilon test useful?

A 42-year-old woman presented to an eye clinic with a 2-week history of diplopia. Examination revealed signs of a right sixth nerve palsy. A computed tomography (CT) brain scan was normal. Six weeks later she presented during the acute medical take with increasing diplopia, a drooping right eyelid and unsteadiness. Direct questioning revealed that the drooping became progressively worse throughout the day. She had no relevant past medical history or any regular medication. Examination revealed a partial right ptosis and signs of right third, fourth and sixth nerve palsy. Diplopia on binocular vision resolved on patch testing; neurological examination was otherwise unremarkable, with no evidence of limb weakness.

A magnetic resonance imaging scan of the brain and CSF examination were unremarkable. Ocular myasthenia was suspected, anti-acetylcholine receptor antibody test was requested, and a Tensilon test was performed with full resuscitation equipment available. Following the administration of the test dose (2 mg) of intravenous edrophonium (Tensilon) a visible improvement in the right ptosis was observed. Subsequent administration of a further 8 mg edrophonium yielded more marked improvement, with complete correction of the right ptosis (Figure 1) and a subjective decrease in diplopia on right gaze. A diagnosis of unilateral ocular myasthenia gravis was made on the basis of the clinical picture and the positive Tensilon test.

A neurological opinion was sought and the patient commenced on pyridostigmine 60 mg four times a day. Further investigations included a CT scan of the thorax which revealed a 2 cm retrosternal mass, compatible with thymic hyperplasia. Five weeks after the positive Tensilon test, a report of strongly positive anti-acetylcholine receptor antibodies (anti-acetylcholine receptor antibodies >8 nmol/litre, normal range 0–0.5 nmol/litre) was received. The diplopia continues to improve and the patient has regular follow up.

Measuring tracheal airway pressures during transtracheal jet ventilation: an observational study*

Tracheal airway pressures were measured via a transduced fibrescope during transtracheal jet ventilation in 10 patients. Ravussin transtracheal jet ventilation catheters were inserted under local anaesthesia. Following induction of general anaesthesia, tracheal airway pressures were measured at three anatomical levels during fibreoptic intubation. Overall pressure changes during transtracheal jet ventilation were small with the maximal pressure increase (13 mmHg) measured at the carina.

Oxidative stress is the master operator of drug and chemically-induced programmed and unprogrammed cell death: Implications of natural antioxidants in vivo

ROS, RNS, BRIs and ROS-RNS hybrids are produced during drug or chemical metabolism in vivo. These reactive species are instrumental to the culmination of cellular oxidative stress (OS). OS, once turned on, does not spare any vital intracellular macromolecule, such as glutathione, DNA, RNA, proteins, enzymes, lipids and ATP. Since concentration gradients of such components are very delicately balanced for normal cellular functioning, a gross perturbation leads to cell injury and cell death. Abundant evidence now suggests that intracellular antioxidants keep OS in check and maintain homeostasis. Our laboratory has focused on the role of OS in orchestrating various forms of cell death during drug and chemically-induced target organ toxicity and their counteraction by various natural or synthetic antioxidants in in vivo models. Despite complexity of the in vivo models, results show that metabolism of xenobiotics are invariably associated with different degrees of OS and natural antioxidants such as grape seed extract, bitter melon extract (Momordica charantia) and N-acetylcysteine (NAC) which were very effective in counteracting organ toxicities by minimizing events linked to OS (lipid peroxidation and total glutathione), and CAD-mediated DNA fragmentation. Phytoextract exposure rescued cells from toxic assaults, protected genomic integrity, and minimized apoptotic, necrotic and apocrotic (oncotic necrosis) cell deaths. Pre-exposure mode was more effective than post-exposure route. Overall scenario suggests that OS may have been the prime modulator of death and/or survival programs, whereas, antioxidants may have imparted a dual role in either erasing death signals or reviving survival signals, and a combination of antioxidants may be more beneficial than a single entity to influence a number of intracellular events operating simultaneously to neutralize chaotic toxicological consequences.

Role of G(i)alpha2-protein in opioid tolerance and mu-opioid receptor downregulation in vivo

Although opioid receptors are G-protein coupled, the role that specific G-protein subunits play in the development of opioid tolerance and the regulation of opioid receptor number is not well understood. In the present study, we used a G((i)alpha2) antisense oligodeoxynucleotide (ODN) to examine the contribution of G((i)alpha2) proteins to mu-opioid tolerance and receptor downregulation in the mouse. Mice were injected intracerebroventricularly (ICV) and into the spinal intrathecal space (IT) for 4-5 consecutive days (30 microg/site/day), with an antisense ODN or a mismatch ODN directed at mRNA for the G((i)alpha2) subunit of G-proteins. Controls were treated with dH(2)O. On the second day of ODN treatment continuous subcutaneous (SC) infusion of etorphine (200 microg/kg/day) or morphine (40 mg/kg/day + 25 mg pellet) was begun. Control mice were implanted with inert placebo pellets. Three days later, pumps and pellets were removed and mice were tested for morphine analgesia or mu-opioid receptor density was determined in whole brain. Etorphine produced significant tolerance (ED(50) shift = approximately 11-fold) and downregulation of mu-opioid receptors (approximately 25%). Morphine treatment produced significant tolerance (ED(50) shift approximately 9-fold), but no mu-opioid receptor downregulation. Antisense treatment reduced G((i)alpha2) protein levels in striatum and spinal cord by approximately 25%. G((i)alpha2) antisense reduced the acute potency of morphine. G((i)alpha2) antisense blocked the development of tolerance to morphine treatment and reduced the development of tolerance to etorphine treatment. Antisense did not have any effect on etorphine-induced mu-opioid receptor downregulation. In another experiment, 7-day treatment with morphine or etorphine similarly increased G((i)alpha2) mRNA and protein abundance in spinal cord. Overall, these results support an important role for G((i)alpha2)-protein in the acute effects of opioids and opioid tolerance. However, G((i)alpha2) is not required for agonist-induced mu-opioid receptor density regulation in vivo.

Resin modified glass-ionomers: strength, cure depth and translucency

BACKGROUND

According to the classification suggested by McLean, Wilson and Nicholson only three materials, currently marketed, fit the designation of resin modified glass-ionomers. These materials will undergo an acid/base setting reaction but also contain a limited quantity of a monomer that will polymerize as a result of irradiation. The quantity of polymer is limited to the extent that it will not interfere with the normal acid/base setting reaction and will therefore allow for the ion exchange adhesion with tooth structure that is typical of glass-ionomer. There is a third setting reaction incorporated to ensure remaining monomer, that is not affected by irradiation, will still polymerize. A series of experiments were carried out to determine the effect of the three types of setting reaction on the strength, depth of cure and translucency of these three materials.

METHODS

Specimens, both with and without irradiation, were subjected to a shear punch strength test. To determine the depth of cure brought about through irradiation, specimens were tested immediately after construction according to the test in ISO - 4049 2000 (E). Translucency is clinically significant and will vary according to whether the material has been subjected to irradiation or cured through the acid/base reaction alone.

RESULTS

The strength of all materials tested was higher in specimens subject to irradiation. The depth of cure was found to be both shade and irradiation time dependent. Irradiated specimens were found to be only marginally more translucent than those allowed to set without irradiation.

CONCLUSIONS

It was concluded that, for cavities more than 3 mm deep, these materials should be placed incrementally to allow for a full irradiation initiated cure.

The cardiovascular response to insertion of the intubating laryngeal mask airway

Sixty-one patients received a standardised anaesthetic and were randomly assigned to three groups: tracheal intubation via direct laryngoscopy, tracheal intubation via an intubating laryngeal mask airway with immediate removal of the device, and tracheal intubation via an intubating laryngeal mask airway with delayed removal. The cardiovascular response to intubation was of a similar magnitude in all groups, although delayed removal of the intubating laryngeal mask airway was associated with a second pressor response. Norepinephrine changed significantly over time following direct laryngoscopy and following immediate removal of the intubating laryngeal mask airway, but not after delayed removal. The findings of this study do not support using the intubating laryngeal mask instead of direct laryngoscopy purely to decrease the response to intubation.

The role of DMSA scans in evaluation of the correlation between urinary tract infection, vesicoureteric reflux, and renal scarring

The correlation between urinary tract infection (UTI), vesicoureteric reflux (VUR) and renal scarring was studied in 89 patients (177 renal units; 1 solitary kidney) during the period 1997-2000. There were 63 males and 26 females; ages ranged from neonates to 14 years. UTI was diagnosed on the basis of a positive urine culture, VUR was diagnosed and graded by micturating cystourethrogram (MCU), and renal scarring was assessed by technetium 99 m Tc-dimercaptosuccinic acid (DMSA) scan. Ultrasonography (US) was done to evaluate renal tract dilatation and other structural abnormalities. A follow up DMSA scan was performed approximately 6 months after the initial scan. VUR was present in 106 of the 171 renal units in which it was studied and absent in 65 units. The majority of the VUR was grade V. Renal scars were seen in 90 of 177 renal units at presentation and in 72 of the 163 renal units studied at follow-up. Some information was lacking in 31 patients; hence, the correlation between UTI, VUR, and renal scarring was done in 58 patients. The majority of the suspected scars at presentation were not seen at follow-up, but most of the established scars persisted. Only 2 renal units showed scars for the first time on follow-up. On US, approximately 50% of normal kidneys showed either suspicious or established scars on DMSA scan, and patients with bilateral abnormality on US showed renal scars. Renal scars were seen in 15 of 23 children without VUR, 17 of 18 with unilateral VUR, and 16 of 17 with bilateral VUR. Thus, there is a cause-and-effect relationship between UTI and renal scarring that is made worse by VUR. DMSA scans have been shown to be the most reliable method of assessing renal scarring, and an abnormal US scan showing upper-tract dilatation or a structural abnormality may have a predictive value in the detection of renal scarring.

Pharmacodynamics and bactericidal activity of moxifloxacin in experimental Escherichia coli meningitis

Moxifloxacin, an 8-methoxyquinolone with broad-spectrum activity in vitro, was studied in the rabbit model of Escherichia coli meningitis. The purposes of this study were to evaluate the bactericidal effectiveness and the pharmacodynamic profile of moxifloxacin in cerebrospinal fluid (CSF) and to compare the bactericidal activity with that of ceftriaxone and meropenem therapy. After induction of meningitis, animals were given single doses of 10, 20, and 40 mg/kg or divided-dose regimens of 5, 10, and 20 mg/kg twice, separated by 6 h. After single doses, the penetration of moxifloxacin into purulent CSF, measured as percentage of the area under the concentration-time curve (AUC) in CSF relative to the AUC in plasma, was approximately 50%. After single doses of 10, 20, and 40 mg/kg, the maximum CSF concentration (C(max)) values were 1.8, 4.2, and 4.9 microg/ml, respectively; the AUC values (total drug) were 13.4, 25.4, and 27.1 microg/ml x h, respectively, and the half-life values (t(1/2)) were 6.7, 6.6, and 4.7 h, respectively. The bacterial killing in CSF for moxifloxacin, calculated as the Deltalog(10) CFU per milliliter per hour, at 3, 6, and 12 h after single doses of 10, 20, and 40 mg/kg were -5.70, -6.62, and -7.02; -7.37, -7.37, and -6.87; and -6.62, -6.62, and -6.62, respectively, whereas those of ceftriaxone and meropenem were -4.18, -5.24, and -4.43, and -3.64, -3.59, and -4.12, respectively. The CSF pharmacodynamic indices of AUC/MBC and C(max)/MBC were interrelated (r = 0.81); there was less correlation with T > MBC (r = 0.74). In this model, therapy with moxifloxacin appears to be at least as effective as ceftriaxone and more effective than meropenem therapy in eradicating E. coli from CSF.

SV40-derived vectors provide effective transgene expression and inhibition of HIV-1 using constitutive, conditional,and pol III promoters

Vectors based on recombinant SV40 viruses (rSV40) are highly effective in delivering transgene expression driven by constitutive promoters. We tested here whether these vectors could be used with conditional promoters and promoters using RNA polymerase III transcription, with inhibition of HIV-1 by Tat activation response (TAR) decoys as a functional measure of effective transgene delivery and activity. TAR decoys inhibit HIV-1 Tat, a trans-activator of HIV-1 transcription. Tat acts early in the viral replicative cycle and is essential for efficient viral replication. We evaluated rSV40 gene delivery using two different inhibitors of Tat. One was a dual function polyTAR gene encoding 25 sequential TAR elements (TAR(25)), plus an antisense tat, driven either by HIV-1 long terminal repeat (HIV-LTR) as a conditional promoter, or by cytomegalovirus immediate-early promoter (CMV-IEP) as a constitutive promoter. The other inhibitor was a single TAR decoy, driven by the U6 small nuclear RNA promoter (U6-P). These decoys were delivered to unselected cells in two different human T lymphocyte lines and to unstimulated primary human peripheral blood mononuclear cells (pbmc). Gene delivery was confirmed by PCR, and expression by RT-PCR. By in situ hybridization analysis, >95% of cells were transduced. These transgene constructs protected all cell types tested from HIV-1, as measured by syncytia formation and p24 antigen release. Somewhat better inhibition of HIV-1 replication was achieved with HIV-1 long terminal repeat (HIV-1 LTR) as a conditional promoter than with the constitutive CMV-IEP. The U6-P was also very effective, driving a TAR(1) transcript. Cell viability was not detectably affected by TAR decoy expression. Thus, rSV40 vectors effectively deliver HIV-1-inhibitory RNAs using either constitutive or conditional pol II promoters, or using a pol III promoter. The versatility of this gene delivery system may prove to be useful in anti-HIV-1 therapeutics.

'Televaluation' of clinical information systems: an integrative approach to assessing Web-based systems

The World Wide Web provides an unprecedented opportunity for widespread access to health-care applications by both patients and providers. The development of new methods for assessing the effectiveness and usability of these systems is becoming a critical issue. This paper describes the distance evaluation (i.e. 'televaluation') of emerging Web-based information technologies. In health informatics evaluation, there is a need for application of new ideas and methods from the fields of cognitive science and usability engineering. A framework is presented for conducting evaluations of health-care information technologies that integrates a number of methods, ranging from deployment of on-line questionnaires (and Web-based forms) to remote video-based usability testing of user interactions with clinical information systems. Examples illustrating application of these techniques are presented for the assessment of a patient clinical information system (PatCIS), as well as an evaluation of use of Web-based clinical guidelines. Issues in designing, prototyping and iteratively refining evaluation components are discussed, along with description of a 'virtual' usability laboratory.

Renal function and structure in subacute hepatic failure

BACKGROUND AND AIMS

Subacute hepatic failure (SHF) is a fatal complicaton of acute viral hepatitis. Renal failure has been implicated as the main cause of death in this disease. However, renal functional and structural evaluation in such patients have not been performed. The present prospective study evaluated the renal functional and structural abnormalities in patients with subacute hepatic failure.

METHODS

Fourteen consecutive patients with SHF, 11 with acute liver failure (ALF) and 15 with cirrhosis of the liver (Child's B or C) were included in the present study. All 40 patients had liver disease caused by hepatitis viruses. The glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) estimations were measured in all patients by the use of technetium-99m diethylenetriaminepentaacetic acid and [131I]-labeled ortho-iodohippuric acid, respectively. Ante-mortem or post-mortem liver biopsies were performed in all patients. In three patients with SHF, post-mortem kidney biopsies were also performed.

RESULTS

Thirty six percent (5/14) of patients with SHF, 18% (2/11) of patients with ALF and 20% (3/15) of patients with cirrhosis had renal failure. Seven patients with SHF, seven with ALF and nine with cirrhosis died. All the patients with renal failure in each of the three groups were among the deceased patients. Glomerular function was markedly affected among patients with SHF, which was shown by significantly higher (P < 0.05) proteinuria levels (0.367 +/- 0.38 g/24 h) compared to levels in patients with ALF (0.178 +/- 0.11 g/24 h) and cirrhosis (0.212 +/- 0.133 g/24 h). The GFR in SHF (56 +/- 27 mL/min per 1.73 m2) and cirrhotic patients (58 +/- 36 mL/min per 1.73 m2) was significantly lower compared to those in ALF patients (102 +/- 51 mL/min per 1.73 m2; P < 0.05). A significantly higher proportion (P < 0.05) of patients with SHF and cirrhosis (64 and 73%, respectively) had a GFR below 80 mL/min per 1.73 m2 compared to patients with ALF (18%). The GFR value among the deceased SHF patients (46 +/- 26 mL/min per 1.73 m2) was significantly lower (P < 0.05) than those SHF patients who survived (65 +/- 25 mL/min per 1.73 m2). However, similar features could not be documented among patients with ALF or cirrhosis. Subtle structural changes in the glomerulus were also noted in patients with SHF. These included mesangial proliferation and thickening, basal membrane thickening and increased cellularity with interstitial edema. The ERPF was markedly reduced (P = 0.058) among patients with SHF (347 +/- 131 mL/min per 1.73 m2) and cirrhosis (395 +/- 137 mL/min per 1.73 m2) in comparison to ERPF documented among patients with ALF (436 +/- 217 mL/min per 1.73 m2). Such a reduction in renal tubular blood flow, along with histologic documentation of hyaline presence, bile and grannular cast in the tubule, indicated a possible tubular dysfunction in patients with SHF.

CONCLUSION

It is concluded that glomerular and tubular dysfunction with subtle structural abnormalities does occur in patients with SHF. These are similar to renal changes in cirrhosis and may have similar pathogenetic mechanisms that require further evaluation.

NaCl-induced hypertensive rat model of non-insulin-dependent diabetes: role of sympathetic modulation

Systemic hypertension is common in individuals with non-insulin-dependent diabetes (NIDD) and, in this population, markedly increases the risk for cardiovascular complications. The aims of this study were to develop a rat model of combined NaCl-induced hypertension and NIDD, and to determine the contribution of the sympathetic nervous system to the development of the manifest hypertension. Two-day old male Wistar-Kyoto rats were injected with either streptozotocin (90 mg/kg, ip; NIDD) or vehicle (citrate buffer; control). At 4 weeks of age, the animals underwent either a right nephrectomy or a sham operation. Animals in each group were further subdivided, with one group maintained on normal (0.72 %) NaCl diet whereas the other was placed on a high (8%)-NaCl diet. At 6 months of age, diabetes was confirmed by glucose tolerance testing. Hemodynamic parameters were measured in the freely moving animal (ia) before and after the administration of prazosin (peripheral alpha1-adrenergic antagonist, iv) or clonidine (central alpha2-adrenergic agonist). The NIDD rat displayed a higher (P < .05) blood glucose concentration than the nondiabetic control rat during the glucose tolerance test. Elevated dietary NaCl significantly increased mean arterial pressure (MAP) in the uninephrectomized, but not the sham-operated groups. Acute administration of prazosin resulted in a significantly greater reduction in MAP of both hypertensive groups than of their normotensive counterparts. Moreover, clonidine caused a significant reduction in MAP of the hypertensive control rat but not in the normotensive controls. By contrast, both the hypertensive NIDD and the normotensive NIDD rats showed a similar reduction in MAP in response to clonidine administration. The data suggest that the combination of uninephrectomy and dietary NaCl excess confers hypertension on the NIDD rat. Moreover, enhancement of the sympathetic pathway plays an important role in the regulation of arterial pressure in the hypertensive NIDD rat.

Comparison of laryngeal mask and intubating laryngeal mask insertion by the naïve intubator

Seventy-five inexperienced participants were timed inserting the laryngeal mask airway (LMA) and the intubating laryngeal mask (ILM) in one of five cadavers. Adequacy of ventilation was assessed on a three-point scale depending on chest expansion and air leak. Participants were also asked to intubate the trachea via the ILM. The ILM was inserted faster than the LMA (P < 0.05) with a greater proportion achieving adequate ventilation after their first attempt (P < 0.05). Tracheal intubation via the ILM was completed successfully by 67% (52 of 75) of participants. In a questionnaire, participants stated that the ILM was easier to use and the preferred device in an emergency. The results suggest that inexperienced practitioners should use the ILM rather than the LMA for emergency ventilation.

Pediatric duodenal perforation demonstrated by hepatobiliary imaging

The diagnosis of intestinal perforation in children is difficult. Computed tomography has been a useful investigative modality. A case of duodenal perforation is presented in which radionuclide hepatobiliary imaging was useful.