Surgical access to the mammalian cochlea for cell-based therapies

Cochlear implants are dependent on functionally viable spiral ganglion neurons (SGNs) — the primary auditory neurons of the inner ear. Cell-based therapies are being used experimentally in an attempt to rescue SGNs from deafness-induced degeneration or to generate new neurons. The success of these therapies will be dependent on the development of surgical techniques designed to ensure precise cell placement while minimizing surgical trauma, adverse tissue reaction and cell dispersal. Using 24 normal adult guinea pigs we assessed three surgical procedures for cell delivery into the cochlea: (i) a cochleostomy into the scala tympani (ST); (ii) direct access to Rosenthal's canal – the site of the SGN soma – via a localized fracture of the osseous spiral lamina (RC); and (iii) direct access to the auditory nerve via a translabyrinthine surgical approach (TL). Half the cohort had surgery alone while the other half had surgery combined with the delivery of biocompatible microspheres designed to model implanted cells. Following a four week survival period the inflammatory response and SGN survival were measured for each cohort and the location of microspheres were determined. We observed a wide variability across the three surgical approaches examined, including the extent of the inflammatory tissue response (TL  RC ≥ ST) and the survival of SGNs (ST > RC  TL). Importantly, microspheres were effectively retained at the implant site after all three surgical approaches. Direct access to Rosenthal's canal offered the most promising surgical approach to the SGNs, although the technique must be further refined to reduce the localized trauma associated with the procedure.     

Reduced human and murine corneal thickness in an Axenfeld-Rieger syndrome subtype

PURPOSE: Axenfeld-Rieger malformations of the anterior segment are clinically heterogeneous, and up to 50% of cases are attributable to PITX2 or FOXC1 mutation. In view of PITX2's contribution to corneal development and the altered CCT in some FOXC1-related cases, this study was undertaken to investigate whether a related phenotype is associated with the PITX2/Pitx2 mutation. METHODS: Central corneal thickness (CCT) was measured in patients and mice with PITX2/Pitx2 mutations. CCT in affected individuals and unaffected first-degree relatives from a large PITX2 mutation pedigree was measured with ultrasonic pachymetry. For murine measurements, the optical coherence tomogram (OCT) was calibrated against plastic films whose thickness had been determined with scanning electron microscopy (SEM). Subsequently, CCT was measured in ex vivo eyes from Pitx2(+/-) and wild-type murine littermates by using OCT. RESULTS: CCT in individuals with the PITX2 mutation (mean 484 microm; range, 425-519; n = 8) was significantly lower than in their unaffected first-degree relatives (mean 582 microm; range, 550-590; n = 5; P = 0.0002, t-test). Scanning electron microscopy (SEM) and OCT measurements of reference films correlated closely (r = 0.9995) and subsequent OCT analysis of murine eyes revealed a significant reduction in CCT in Pitx2(+/-) compared with wild-type littermates (Pitx2(+/-): mean, 72 microm; range, 57-87, n = 6; wt: mean, 88 microm; range, 63-100; n = 6, P = 0.035, t-test). CONCLUSIONS: The results show that PITX2/Pitx2 mutation results in reduced corneal thickness and provides the first example of reduced CCT in a genetic subtype of glaucoma. These data will facilitate management of developmental glaucoma and offer potential for guiding molecular genetic testing in patients with Axenfeld-Rieger. The similar CCT reduction observed in patients and mice with comparable mutations emphasizes the utility of this murine model. The technical advance of optical murine CCT measurement also provides scope for serial in vivo imaging of the developing anterior segment and determining the effects of altered CCT on measured IOP.     

Eliciting Stated Preferences for Health-Technology Adoption Criteria Using Paired Comparisons and Recommendation Judgments

OBJECTIVES: The principal aim of this study was to illustrate applying discrete-choice methods for eliciting preferences for technology adoption criteria, including threshold values for cost-effectiveness ratios. A secondary objective was to compare the criteria weights of a sample of industry stakeholders with the results obtained from a study of National Institute for Health and Clinical Excellence (NICE) recommendations. METHODS: We administered a two-stage stated-preference (SP) question format to a sample of respondents who have expertise in applying economic analysis to technology adoption decisions. We elicited paired comparisons and recommendation judgments for similar criteria from a sample of International Society for Pharmacoeconomics and Outcomes Research members. Respondents evaluated nine pairs of hypothetical drugs, first indicating which drug was "better," then indicating what they would recommend to a reimbursement authority such as the National Health Service. Stated-choice studies often obtain only paired-comparison judgments. RESULTS: Parameter estimates from the initial paired-comparison question indicate only incremental cost-effectiveness ratio and number of affected patients influence evaluations. These two factors have identical weights in the second recommendation question, but all four factors were considered in determining the recommendation threshold. Our sample was more willing than NICE to accept trade-offs between cost-effectiveness and other drug features and was less concerned about cost-effectiveness ratios and information uncertainty. Nevertheless, our sample was in agreement with NICE about the importance of the number of patients who would benefit as a criterion for influencing adoption recommendations. CONCLUSION: This study demonstrates that including a question allowing respondents the opportunity to reject both alternatives in a forced-choice paired comparison can be important for obtaining accurate preference estimates. Our results demonstrate that SP methods offer a feasible means of quantifying a broad set of valuations that incorporate the preferences of patient, citizen, payer, and other stakeholder groups.     

Novel antiprotozoal products: imidazole and benzimidazole N-oxide derivatives and related compounds

The syntheses and biological evaluation of the first anti-protozoa imidazole N-oxide and benzimidazole N-oxide and their derivatives are reported. They were tested in vitro against two different protozoa, Trypanosoma cruzi and Trichomonas vaginalis. Derivative 7c, ethyl-1-(i-butyloxycarbonyloxy)-6-nitrobenzimid-azole-2-carboxylate, displayed activity on both protozoa. Lipophilicity and redox potential were experimentally determined in order to study the relationship with activity of the compounds. These properties are well related with the observed bioactivity. Imidazole and benzimidazole N-oxide derivatives are becoming leaders for further chemical modifications and advanced biological studies.     

Analgesic-antiinflammatory properties of Proustia pyrifolia

The antiinflammatory (per os and topic) and analgesic (per os) properties of the aerial part of Proustia pyrifolia a species in danger of extinction were investigated, and the major compounds of two of its active extracts were isolated. In addition, the evaluation of cytotoxicity in three tumoral cell lines and the acute toxicity of the crude methanol extract were also assayed, together with the antioxidant activity for the different extracts of this species. The results of the evaluation of the topic antiinflammatory activities induced by arachidonic acid, and phorbol 12-myristate 13-acetate of the different extracts showed that this species possesses active constituents that could diminish cyclo-oxygenase and lipoxygenases activities, the enzymes that allow the synthesis of proinflammatory endogenous substances as prostaglandin E(2) and leukotrienes, respectively. Our results corroborate the antiinflammatory and analgesic effects of Proustia pyrifolia, and could justify its use in folk medicine for the treatment of rheumatic and gout illnesses. From bio-active extracts beta-sitosterol, quercetin and dihydroquercetin were obtained, and these compounds could explain in part the antiinflammatory, analgesic and antioxidant activities of this species. The crude methanol extract did not present acute toxicity or cytotoxic activity, however only this extract exhibited antioxidant activity.     

Secondary signet-ring cell tumour of the prostate derived from a primary gastric malignancy

Primary signet-ring cell carcinoma of the prostate is infrequent and even more so as secondary spread of this pathologic sub-type to the prostate. We describe the sixth reported case with a diagnosis of a secondary signet-ring cell tumour of the prostate secondary to a gastric cancer. Five years post-gastrectomy to resect signet-ring cell carcinoma, we detected a secondary intra-prostatic spread with urinary tract obstruction. The physical appearance of the tumour cells was similar to that of the previously-resected signet-cell carcinoma of the stomach. There were no metastases in other sites and the patient was treated with radiotherapy. When confronted with intra-prostatic signet-ring cell adenocarcinoma it is necessary to distinguish between primary and secondary aetiology since this would reflect in the choice of treatment and prognosis.     

Effects of 5-isosorbide mononitrate and propranolol on subclinical hepatic encephalopathy and renal function in patients with liver cirrhosis

BACKGROUND/AIMS: In patients with cirrhosis pharmacological treatment of portal hypertension using beta-blockers and vasodilators has raised concerns for its potential deleterious effects on renal function and encephalopathy. To clarify this issue we evaluated the effects of propranolol and 5-isosorbide mononitrate or both on subclinical hepatic encephalopathy and renal function in a prospective randomized double-blinded study. METHODOLOGY: Thirty patients Child-Pugh A or B, with esophageal varices, normal renal function and non-previous pharmacological treatment were studied. After a basal period, patients received during 4 weeks 5-isosorbide mononitrate (80 mg/day) or placebo. In the next 4 weeks, propranolol was added to both groups. At baseline and at the end of each study period we assessed: renal function tests; plasma renin activity and aldosterone; subclinical hepatic encephalopathy (electroencephalograms, visual evoked potentials and psychometric studies). Mean arterial pressure, cardiac output (echo-Doppler) and indocyanine green retention were also measured. RESULTS: The most common alterations at baseline were increased arterial ammonia levels (85%), abnormal indocyanine green retention (75%), abnormal trail making B (44%), decreased inulin clearance (30%) and high plasma renin activity (27%). After 4 weeks of 5-isosorbide mononitrate or placebo no significant changes were observed in any variable. Five out of 14 patients receiving 5-isosorbide mononitrate were withdrawn due to side effects. The addition of propranolol decreased significantly plasma renin activity in both groups and cardiac output in those receiving 5-isosorbide mononitrate but did not change other variables. CONCLUSIONS: In patients with compensated or slightly decompensated liver cirrhosis 5-isosorbide mononitrate, propranolol or the association of both did not produce detectable worsening of subclinical hepatic encephalopathy or renal function.     

Transport and temperature effects on measurement of serum and plasma potassium

Transport of blood samples from general practice to a central laboratory can result in spuriously high or low potassium concentrations. The importance of this phenomenon was studied in a general practice serving a population of 15,000 patients, 27 km from the pathology laboratory that routinely measured serum potassium. The design involved comparison of potassium levels between control serum (plain gel-separation serum tubes centrifuged in the surgery), routine serum (plain gel-separation tubes centrifuged in the laboratory) and routine plasma samples (lithium-heparin tubes centrifuged in the laboratory). Complete triple sets of data were obtained for 371 samples. Altman and Bland plots for the control serum vs routine serum samples showed a mean difference of +0.1 mmol/L with limits of agreement (+/- 2SD) +0.6 mmol/L, -0.4 mmol/L and for control serum vs routine plasma a mean difference of +0.2 mmol/L with limits of agreement +0.8 mmol/L, -0.4 mmol/L. There was a negative association between mean weekly routine plasma potassium levels with mean weekly temperatures achieved. Regression analysis indicated that both maximum temperature achieved and time to centrifugation significantly contributed to differences observed in the routine plasma samples, but not with the routine serum samples. For plasma samples exposed to high temperatures a clinically significant lowering of potassium concentrations can arise. These results confirm that spurious lowering of potassium concentrations occurs in plasma samples collected in a primary care setting. The preferred method is to centrifuge samples soon after venepuncture. Where this is not possible, collection into plain gel-separation tubes (serum) ensures less variation due to temperature and time to centrifugation than does collection into lithium-heparin tubes (plasma).     

What factors influence cataract waiting list time?

AIMS: To determine whether there were any specific factors that influenced waiting list time (WLT) for patients undergoing cataract surgery. METHODS: 70 preoperative cataract patients were interviewed by one of the authors using a questionnaire to score visual acuity, coexisting ocular pathology and disabilities, threat to independent living/employment, and perceived visual handicap for detailed, gross, and driving vision. Individuals were analysed separately according to whether it was their first or second cataract operation. RESULTS: The median WLT for first eye surgery was 9 months (n = 31) and 13 months for second eye surgery (n = 36). The WLT ranged from 2 to 25 months for first eyes and 0.25-18 months for second eyes. Where there was a perceived threat to independent living or employment the WLT was found to be significantly shorter than the median. A high overall score correlated with a shorter WLT. Surgical priority was also given to individuals with anisometropia >3 dioptres. CONCLUSION: This study has demonstrated that there are specific factors that influence clinicians when prioritising patients for cataract surgery.