Outcomes of patients on second- and third-line ART enrolled in ART adherence clubs in Maputo, Mozambique.

OBJECTIVES: Adherence clubs (AC) offer patient-centred access to antiretroviral therapy (ART) while reducing the burden on health facilities. AC were implemented in a health centre in Mozambique specialising in patients with a history of HIV treatment failure. We explored the impact of AC on retention in care and VL suppression of these patients. METHODS: We performed a retrospective analysis of patients enrolled in AC receiving second- or third-line ART. The Kaplan-Meier estimates were used to analyse retention in care in health facility, retention in AC and viral load (VL) suppression (VL < 1000 copies/mL). Predictors of attrition and VL rebound (VL ≥ 1000 copies/mL) were assessed using multivariable proportional hazards regression. RESULTS: The analysed cohort contained 699 patients, median age 40 years [IQR: 35-47], 428 (61%) female and 97% second-line ART. Overall, 9 (1.3%) patients died, and 10 (1.4%) were lost to follow-up. Retention in care at months 12 and 24 was 98.9% (95% CI: 98.2-99.7) and 96.4% (95% CI: 94.6-98.2), respectively. Concurrently, 85.8% (95% CI: 83.1-88.2) and 80.9% (95% CI: 77.8-84.1) of patients maintained VL suppression. No association between predictors and all-cause attrition or VL rebound was detected. Among 90 patients attending AC and simultaneously having VL rebound, 64 (71.1%) achieved VL resuppression, 10 (11.1%) did not resuppress, and 14 (15.6%) had no subsequent VL result. CONCLUSION: Implementation of AC in Mozambique was successful and demonstrated that patients with a history of HIV treatment failure can be successfully retained in care and have high VL suppression rate when enrolled in AC. Expansion of the AC model in Mozambique could improve overall retention in care and VL suppression while reducing workload in health facilities.

OBJECTIFS: Les clubs d'adhésion (CA) offrent un accès centré sur le patient à la thérapie antirétrovirale (ART) tout en réduisant la charge des établissements de santé. Les CA ont été mis en œuvre dans un centre de santé au Mozambique spécialisé dans les patients ayant des antécédents d'échec du traitement du VIH. Nous avons exploré l'impact des CA sur la rétention dans les soins et la suppression de la CV chez ces patients. MÉTHODES: Nous avons effectué une analyse rétrospective des patients enrôlés dans les CA sous ART de deuxième ou troisième intention. Les estimations de Kaplan-Meyer ont été utilisées pour analyser la rétention dans les soins dans les établissements de santé, la rétention dans les CA et la suppression de la charge virale (CV) (CV <1000 copies/mL). Les prédicteurs de l'attrition et du rebond de la CV (VL ≥ 1000 copies/mL) ont été évalués à l'aide d'une régression à risques proportionnels multivariés. RÉSULTATS: La cohorte analysée contenait 699 patients, d'âge médian 40 ans [IQR: 35-47], 428 (61%) femmes, 97% de traitement de deuxième intention. Dans l'ensemble, 9 (1,3%) patients sont décédés, 10 (1,4%) ont été perdus de vue. La rétention dans les soins à 12 et 24 mois était de 98,9% (IC95%: 98,2-99,7) et de 96,4% (IC95%: 94,6-98,2), respectivement. De même, 85,8% (IC95%: 83,1-88,2) et 80,9% (IC95%: 77,8-84,1) des patients ont maintenu une suppression de la CV. Aucune association entre les prédicteurs et l'attrition toutes causes ou le rebond de la CV n'a été détectée. Parmi 90 patients enrôlés dans les CA et ayant simultanément un rebond de la CV, 64 (71,1%) ont atteint une re-suppression de la CV, 10 (11,1%) n'ont pas atteint une re-suppression et 14 (15,6%) n'avaient pas de résultats de CV ultérieurs. CONCLUSION: La mise en œuvre des CA au Mozambique a été un succès et a démontré que les patients ayant des antécédents d'échec du traitement anti-VIH peuvent être retenus avec succès dans les soins et ont un taux élevé de suppression de la CV lorsqu'ils sont enrôlés dans les CA. L'expansion du modèle CA au Mozambique pourrait améliorer la rétention globale dans les soins et la suppression de la CV tout en réduisant la charge de travail dans les établissements de santé.

Spectroscopic characterization of N-doped single-walled carbon nanotube strands: an X-ray photoelectron spectroscopy and Raman study.

We have studied in detail the carbon and nitrogen bonding environments in nitrogen-doped single-walled carbon nanotubes (SWCNTs). The samples consisting of long strands of N-doped SWCNTs were synthesized using an aerosol assisted chemical vapor deposition method involving benzylamine-ethanol-ferrocene solutions. The studied samples were produced using different benzylamine concentrations in the solutions, and exhibited a maximum concentration of ca. 0.3%at of N, determined by X-ray photoelectron spectroscopy (XPS). In general, we observed that the ratio between substitutional nitrogen and the pyridine-like bonded nitrogen varied upon the precursor composition. Moreover, we have observed that the sp2-like substitutional configuration of the C-N bond does not exceed the 50% of the total N atomic incorporation. In addition, we have characterized all these samples using Raman spectroscopy and electron microscopy.

Temperature-dependent infrared ellipsometry of Mo-doped VO2 thin films across the insulator to metal transition.

We present a spectroscopic ellipsometry study of Mo-doped VO2 thin films deposited on silicon substrates for the mid-infrared range. The dielectric functions and conductivity were extracted from analytical fittings of Ψ and Δ ellipsometric angles showing a strong dependence on the dopant concentration and the temperature. Insulator-to-metal transition (IMT) temperature is found to decrease linearly with increasing doping level. A correction to the classical Drude model (termed Drude-Smith) has been shown to provide excellent fits to the experimental measurements of dielectric constants of doped/undoped films and the extracted parameters offer an adequate explanation for the IMT based on the carriers backscattering across the percolation transition. The smoother IMT observed in the hysteresis loops as the doping concentration is increased, is explained by charge density accumulation, which we quantify through the integral of optical conductivity. In addition, we describe the physics behind a localized Fano resonance that has not yet been demonstrated and explained in the literature for doped/undoped VO2 films.

mRNA from frog corneal epithelium increases water permeability in Xenopus oocytes.

PURPOSE: To investigate the existence of a water channel in the frog corneal epithelium by studying the osmotic water permeability (Pf) of Xenopus oocytes expressing the mRNA message from frog corneal epithelium. METHODS: Total RNA was obtained from corneal epithelium by a single-step phase separation method, and poly A+ RNA was isolated using oligo-dT columns. This mRNA was injected into the oocytes. After a 48-hour incubation, oocyte volume changes elicited by a hypoosmotic solution were measured with a computerized video system. RESULTS: Oocytes injected with 50 nl mRNA (1 microgram/microliter) showed a significant increase in Pf compared to water-injected controls (8.4 +/- 1.5 to 17.5 +/- 1.9 cm.sec-1 x 10(-4), P < 0.005). mRNA-injected oocytes exposed to a higher external [Cl-] showed a heightened permeability. Furthermore, Pf of oocytes exposed to a solution containing the recognized water-channel blocker HgCl2 was significantly lower than the Pf of mRNA-injected oocytes not exposed to HgCl2. CONCLUSIONS: Evidence was found for a water channel in the frog corneal epithelium because oocytes injected with the epithelial mRNA manifested increased water permeability. The increase in water permeability was larger in the presence of external Cl- and was inhibited by HgCl2. This finding correlates with measurements of Pf in the intact epithelium in which apical Cl- induced an increase in transepithelial water permeability prevented by HgCl2.

Adreno-cholinergic modulation of junctional communications between the pigmented and nonpigmented layers of the ciliary body epithelium.

PURPOSE: Cell-to-cell communications between the epithelial layers of the ciliary body may be critical for aqueous humor production. The aim of this study was to identify pharmacologic agents that affect this path. METHODS: Whole New Zealand rabbit ciliary bodies were mounted in Ussing-type chambers with Ca2+(-)free and Ca2+(-)rich Tyrode's in the nonpigmented (NPE; aqueous) and pigmented (PE; serosa) epithelial side hemichambers, respectively. The NPE of the PE were then permeabilized, either selectively to monovalent ions with amphotericin B or nonselectively to small solutes with digitonin. Resultant active transport activities were tracked as short circuit currents (ISCS). RESULTS: Permeabilization of the NPE with either 10 microM amphotericin B or 10 micro M digitonin led to an aqueous-to-serosa-positive ISC. This ISC was inhibited by serosal-side ouabain and heptanol, indicating movement of Na+ from permeabilized NPE to the PE by the interlayer junctional path, followed by PE-to-serosa active Na+ transport. Permeabilization of the PE with amphotericin B elicited an ISC in the opposite direction, This ISC was abolished by aqueous-side ouabain and by heptanol, consistent with sequential PE to NPE Na+ translocation, followed by active, NPE-to-aqueous transport. Acetylcholine, epinephrine, norepinephrine, and the alpha 1-adrenergic agonist phenylephrine, but not brominidine, an alpha 2-adrenergic agonist, each caused an approximately 50% reduction of these currents. The inhibitions were fully dependent on serosal-side Ca2+ and were blocked by one calmodulin inhibitor, trifluoperazine, but not by another, calmidazolium. CONCLUSIONS: The above observations provide evidence that cholinergic or alpha 1-adrenergic activation of the PE causes Ca2+(-)dependent inhibition of the NPE-PE junctional path. A triflouperazine-sensitive entity, which may be distinct from calmodulin, is involved in the inhibition.

Effects of Ca2+ on rabbit translens short-circuit current: evidence for a Ca2+ inhibitable K+ conductance.

PURPOSE: To characterize the effects of medium Ca2+ levels on rabbit lens electrical properties. Early studies with wholly submerged lenses had shown that Ca2+ removal from the bath resulted in an increased Rb+ efflux, a consequence of an increased Na+ Permeability and lens depolarization. METHODS: Lenses were bathed with Ussing-type chambers under short-circuited conditions, an arrangement in which the translens short-circuit current (Isc) is carried out across the posterior lens surface mainly by an influx of Na+, and across the anterior face largely by a K+ efflux. RESULTS: Under the present conditions in which the effects of Ca2+ were characterized unilaterally, the above established effects could only be ascribed to the posterior surface. When Ca2+ removal was limited to the anterior face, the Isc increased from 11.87 +/- 1.17 to 17.04 +/- 1.52 microA/cm2 (means +/- SE's, n = 18; an accompanying translens resistance (Rt) decrease of 0.23 +/- 0.049 K omega.cm2 was also recorded). Conversely, increasing the control, anterior-bath [Ca2+] from 1.8 to 3.6 mM reduced the K+ efflux-dependent Isc from 10.54 +/- 1.09 to 8.93 +/- 1.02 (n = 10, with an Rt increase of 0.11 +/- 0.013). These changes were reversible Na(+)-independent, and fully inhibited by the presence of K+ channel blockers (quinidine or Ba2+). Inhibitions of the Ca2+ effects were also obtained with strontium, a Ca2+ surrogate. The Isc was less responsive to changes in the Ca2+ content of the posterior bath. Removal of the cation caused a gradual 1.65 +/- 0.72 microA/cm2 increase (n = 9, with an Rt decrease of 0.090 +/- 0.021 K omega.cm2). In the absence of posterior Na+, Ca2+ withdrawal resulted in highly variable responses, with some specimens exhibiting salient current increases, suggesting that an outwardly directed, posterior efflux of an anion could also have been affected. During the course of this study it was consistently observed that the removal of Na+ from the anterior bath led to an Isc decrease of 2.62 +/- 0.22 microA/cm2 (n = 32, with an Rt increase of 0.35 +/- 0.029 k omega.cm2). This change occurred in both the presence of ouabain and the absence of Ca2+, suggesting that it did not result from an inhibition of the Na(+)-K+ pump current nor from a reversal in putative Na+/Ca2+ exchange activity. Small Isc increases upon anterior Na+ withdrawal (1.68 +/- 0.17, n = 7), consistent with Na+ efflux from the lens, could only be observed with K+ channels inhibited with Ba2+. Also congruent with the observations of a relatively limited anterior Na+ permeability, was the finding that the induction of nonspecific cation channels with amphotericin B reduced the Isc by following Na+ from the anterior bath to enter the lens. Thus, changes in lens Isc can differentiate changes in K+ permeability across the native anterior epithelium from changes in Na+ permeability. CONCLUSIONS: Overall, these results suggest that lens Ca2(+)-mobilizing agents (e.g. acetylcholine) could trigger the inhibition of epithelial K+ conductance(s) by the direct action of Ca2+ on K+ channels.

Post-match disorder: how to cope when your program fails to match.

BACKGROUND: Faculty, residents, and staff of programs that fail to match in the National Resident Matching Program may develop a Post-Match Disorder (PMD) that can threaten a program's self-esteem, teamwork, and ability to function. The symptoms of PMD include manifestations of shock, anger, and depression. This report describes the experience of one program that unexpectedly failed to match and the subsequent development of PMD among program personnel. METHODS: A survey of applicants who did not match with the program was conducted. RESULTS: The results indicated that the applicants perceived the program as having many positive attributes and had ranked it highly--but not high enough to match. CONCLUSIONS: The awareness that applicants perceived the program positively helped alleviate symptoms of PMD and allowed faculty and residents to focus on subsequent resident recruitment, leading to a successful match in the following year.

Hipomagnesemia en el embarazo: ¿factor de riesgo de preeclampsia severa? / Hypomagnesemia during pregnancy: Risk factor for severe preeclampsia?

Resumen Objetivo: Demostrar que la hipomagnesemia es un factor de riesgo de preeclampsia severa. Materiales y métodos: Estudio de casos y controles efectuado en pacientes atendidas en el Hospital de la Mujer entre los meses de enero de 2015 a enero de 2016. Grupo de estudio: pacientes con preeclampsia severa y controles embarazadas sanas, con determinación de las concentraciones de magnesio sérico. Resultados: Se estudiaron 200 pacientes; la edad media de las embarazadas hipertensas fue de 24.6 años, y 23.5 años de las normotensas. La diferencia entre ambas fue de 1.1 años (p > 0.05). La mediana en semanas de gestación de las mujeres hipertensas fue de 37 y de 39 para las sanas, respectivamente; la diferencia fue de 2 (p = 0.0001). La mediana del magnesio de las mujeres hipertensas fue de 1.7 mg/dL, y en las no hipertensas 1.8 mg/dL, (p = 0.0053); RM: 1.72 IC95%: 1.0- 3.13; p = 0.005. Conclusiones: Se demuestra que la hipomagnesemia es un factor de riesgo de preeclampsia severa.

Abstract Objective: To demonstrate that hypomagnesemia is a risk factor for severe preeclampsia. Materials and methods: A case-control study conducted in patients treated at the Hospital de la Mujer between the months of January 2015 and January 2016. The study group included patients with severe preeclampsia and healthy pregnant controls with determination of concentrations of magnesium serum. Results: 200 patients were studied; the average age of the hypertensive pregnant women was 24.6 years, and 23.5 years of the normotensive women. The difference between the two was 1.1 years (p > 0.05). The median in weeks of gestation of hypertensive women was 37 and 39 for healthy women, respectively; the difference was 2 (p = 0.0001). The median magnesium of the hypertensive women was 1.7 mg/dL, and in the non-hypertensive 1.8 mg/dL, (p = 0.0053); RM: 1.72 IC95%: 1.0- 3.13; p = 0.005. Conclusions: in this study group, it was shown that hypomagnesemia is a risk factor for severe preeclampsia.

Volume change of the ocular lens during accommodation.

During accommodation, mammalian lenses change shape from a rounder configuration (near focusing) to a flatter one (distance focusing). Thus the lens must have the capacity to change its volume, capsular surface area, or both. Because lens topology is similar to a torus, we developed an approach that allows volume determination from the lens cross-sectional area (CSA). The CSA was obtained from photographs taken perpendicularly to the lenticular anterior-posterior (A-P) axis and computed with software. We calculated the volume of isolated bovine lenses in conditions simulating accommodation by forcing shape changes with a custom-built stretching device in which the ciliary body-zonulae-lens complex (CB-Z-L) was placed. Two measurements were taken (CSA and center of mass) to calculate volume. Mechanically stretching the CB-Z-L increased the equatorial length and decreased the A-P length, CSA, and lens volume. The control parameters were restored when the lenses were stretched and relaxed in an aqueous physiological solution, but not when submerged in oil, a condition with which fluid leaves the lens and does not reenter. This suggests that changes in lens CSA previously observed in humans could have resulted from fluid movement out of the lens. Thus accommodation may involve changes not only in capsular surface but also in volume. Furthermore, we calculated theoretical volume changes during accommodation in models of human lenses using published structural parameters. In conclusion, we suggest that impediments to fluid flow between the aquaporin-rich lens fibers and the lens surface could contribute to the aging-related loss of accommodative power.

Production and characterization of single-crystal FeCo nanowires inside carbon nanotubes.

We describe the synthesis of novel monocrystalline FeCo nanowires encapsulated inside multiwalled carbon nanotubes (MWNTs). These FeCo nanowires exhibit homogeneous Fe and Co concentrations and do not contain an external oxide layer due to the presence of insulating nanotube layers. The method involves the aerosol thermolysis of toluene-ferrocene-cobaltocene solutions in inert atmospheres. The materials have been carefully characterized using state-of-the-art high-resolution transmission electron microscopy (HRTEM), electron-energy-loss spectroscopy (EELS), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), electron diffraction, HREELS-STM elemental mapping, X-ray powder diffraction, and SQUID magnetometry. We noted that the formation of FeCo alloys occurs at relatively low pyrolytic temperatures (e.g., 650-750 degrees C). These single-crystal nanowires, which have not been reported hitherto, always exhibit the FeCo (110) plane parallel to the carbon nanotube axis. The FeCo nanomaterials have shown large coercive fields at room temperature (e.g., 900 Oe). We envisage that these aligned ferromagnetic nanowires could be used in the fabrication of high-density magnetic storage devices and magnetic composites.

Cl secretagogues reduce basolateral K permeability in the rabbit corneal epithelium.

The stromal-to-tear transport of Cl by the rabbit corneal epithelium is increased by pharmacological effectors (secretagogues) that raise cAMP. It is well established that such secretagogues increase the apical membrane permeability to Cl and thus facilitate the efflux of the anion. However, we and others have found that cAMP-elevating agents frequently decrease the transepithelial potential difference across the rabbit cornea. The mechanism underlying this latter phenomenon had not been characterized. In this report, transepithelial and microelectrode studies were combined with measurements of unidirectional fluxes of 36Cl, 22Na and 86Rb to show that secretagogues known to act via cAMP also decrease the K permeability of the basolateral membrane, which by cellular depolarization would decrease apical Cl secretion. This effect was increasingly pronounced as a function of concentration when agents (e.g., epinephrine, isoproterenol) were applied to the apical side of the preparations. The addition of these agonists to the basolateral bathing solution, or of forskolin to the apical side, solely elicited inhibitions of basolateral K permeability. It seems that apical Cl and basolateral K conductances are independently and inversely regulated by cAMP. The opposite effects that cAMP could have on fluid secretion and epithelial thickness, by increasing apical Cl permeability but decreasing basolateral K permeability, may serve as a mechanism to maintain epithelial thickness within a narrow range.

Chloride-activated water permeability in the frog corneal epithelium.

We have previously reported that the isolated frog corneal epithelium (a Cl(-)-secreting epithelium) has a large diffusional water permeability (Pdw approximately 1.8 x 10(-4) cm/s). We now report that the presence of Cl- in the apical-side bathing solution increases the diffusional water flux, Jdw (in both directions) by 63% from 11.3 to 18.4 microliters min-1.cm-2 with 60 mM [Cl] exerting the maximum effect. The presence of Cl- in the basolateral-side bathing solution had no effect on the water flux. In Cl(-)-free solutions amphotericin B increased Jdw by 29% but only by 3% in Cl(-)-rich apical-side bathing solution, suggesting that in Cl(-)-rich apical side bathing solution, the apical barrier is no longer rate limiting. Apical Br- (75 mM) also increased Jdw by 68%. The effect of Cl- on Jdw was observed within 1 min after its addition to the apical-side bathing solution. HgCl2 (0.5 mM) reduced the Cl(-)-increased Pdw by 31%. The osmotic permeability (Pf) was also measured under an osmotic gradient yielding values of 0.34 and 2.88 (x 10(-3) cm/s) in Cl(-)-free and Cl(-)-rich apical-side bathing solutions respectively. It seems that apical Cl-, or Cl- secretion into the apical bath could activate normally present but inactive water channels. In the absence of Cl-, water permeability of the apical membrane seems to be limited to the permeability of the lipid bilayer.

Potassium current oscillations across the rabbit lens epithelium.

Rabbit lenses expressing spontaneous oscillations in translens short-circuit current (Isc) are obtained somewhat frequently, with this phenomenon observed in approximately 30% of isolated lenses as described earlier (Exp. Eye Res. 61, 129-140, 1995). Since pharmacological protocols to consistently elicit Isc oscillations were not found, characterizations of the underlying transport processes have been limited to the application of various inhibitors on the spontaneous phenomenon. The present report extends the initial observations by confirming that oscillations are immediately inhibited upon the anterior addition of the Ca2+ channel blocker nifedipine (10 microM), and by demonstrating that other treatments which should affect epithelial Ca2+ homeostasis are also inhibitory (e.g., Bay K 8644 (10 microM), diltiazem (10 microM), EGTA (2 mm), and Ca2+-free media). Furthermore, Isc oscillations are immediately inhibited by the K+ channel blocker, Ba2+, but not by the Na+-K+ pump inhibitor, ouabain. The intracellular Ca2+ mobilizing agents thapsigargin (0.1 microM) or acetylcholine (1 microM) modified but did not permanently inhibit the oscillations, confirming earlier observations. At 50 microM, however, acetylcholine addition was inhibitory, but reversible, for oscillations restarted upon its subsequent removal. In addition, lens oscillations were also characterized under open-circuit conditions with microelectrodes inserted in the superficial cells near the equator of lenses isolated in a divided chamber. The potential difference (PD) across each lens face was recorded, as was the translens PD (PDt), which equals the difference between the PDs across each lens surface. Oscillations in PDt were obtained in 7 of 26 lenses. The oscillations arose only from an oscillation in the PD across the anterior face (PDa). While PDa and PDt oscillated with the same amplitude (approximately 12 mV) and period (approximately 70 sec), the PD across the posterior surface remained stable. During these oscillations the conductance of the anterior surface was maximal at the most positive voltage of the anterior bath with respect to the lens interior (46 mV), whereas, minimal conductance occurred at the least positive PDa (34 mV). Overall, these observations are consistent with the likely presence of voltage-operated Ca2+ channels in parallel with various Ca2+-sensitive K+ channels in the epithelial basolateral membrane. A model to explain the oscillatory pattern across the anterior face while the PD across the posterior face remains unaltered is presented.

Acetylcholine modulation of the short-circuit current across the rabbit lens.

Rabbit lenses were bathed within a bicameral Ussing-type chamber under short-circuit conditions. In this situation the short-circuit current (Isc) reflects, across the anterior aspect, the presence of anteriorly facing K+ conductance(s) plus the Na(+)-K+ pump current. Across the posterior surface the Isc is primarily carried by the movement of Na+ from the posterior bathing solution to the lens. Addition of acetylcholine (ACh) to the posterior hemichamber did not affect the translens electrical parameters; but, its introduction to the anterior bath at 1 microM immediately reduced the Isc from 8.91 +/- 1.47 to 5.84 +/- 1.28 microA cm-2 and increased the translens resistance from 1.50 +/- 0.08 to 1.59 +/- 0.09 K omega cm2 (+/- S.E.S; P < 0.05 as paired values, n = 25 lenses). The suppressed Isc gradually recovered and reached 75% of the control value 5 min after the introduction of the neurotransmitter. In six cases the recovery was nearly complete (> or = 95% of control) within this time. The preaddition of 0.1 microM atropine prevented an effect by 1 microM ACh. When atropine was added within 1 min of ACh, the suppressed Isc immediately recovered. The ACh-elicited Isc suppression was averted in lenses pre-exposed to either K+ channel blockers (quinidine or barium) or to the endoplasmic reticular Ca(2+)-ATPase inhibitor thapsigargin (Tg: 0.1 microM), which in itself produced Isc inhibitions similar to those seen with ACh under control conditions. Similarly comparable were the ACh-evoked Isc inhibitions garnered upon introduction of the agonist to lenses bathed in the absence of extracellular Ca2+. In these cases, however, the Isc recovered fully within 2-3 min. This condition also revealed that the anterior removal of medium Ca2+ increased the Isc by about 50%, a completely reversible phenomenon; Ca2+ restoration in the presence of the Ca2+ channel blocker, nifedipine (10 microM), blunted markedly the reversal to the control Isc. Overall, these results suggest that ACh receptor activation induces the release of intracellularly stored Ca2+, which in turn leads to the temporary deactivation of a K+ conductance(s); in addition, secondary Ca2+ inflow may further extend the observed inhibition. During this study, the Isc of about 30% of the lenses used spontaneously oscillated (common duration of 30 min, with a mean peak frequency of 0.76 +/- 0.32 cycle min-1 and mean amplitude of 4.07 +/- 2.65 microA cm-2; +/- S.D.S, n = 24). Experiments attempted to determine the sensitivity of the oscillatory activity to ACh. Tg, nifedipine, and the phorbol ester PMA.(ABSTRACT TRUNCATED AT 400 WORDS)