Results of vitreous surgery for posterior complications of chronic uveitis

To determine surgical results and predictive factors of final visual acuity, a total of 30 eyes in 30 uveitis patients who underwent vitreous surgery including pars plana vitrectomy were followed for at least 6 months and various preoperative factors and postoperative results were analyzed. Our surgical indications were vitreous opacity, traction retinal detachment, combined rhegmatogenous-traction detachment. Preoperatively detached retina was finally reattached in 15 (83.3%) of 18 eyes. Final visual acuity improved in 19 (63.3%) of 30 eyes, but decreased in 3 eyes compared with the initial acuity. Cystoid macular edema was the main cause of poor visual acuity after surgery. Eyes with good final visual acuity showed relatively normal electroretinograms before surgery, but the relationship between them was not statistically significant. Duration of postoperative inflammation affected final visual acuity significantly. These results suggest that chronic uveitis patients with vitreoretinal complications can be managed by vitreous surgery with good anatomic and functional results.

The curvature elastic-energy function of the lipid-water cubic mesophase

Cell and lipid membranes are able to bend, as manifested during membrane fusion and the formation of non-lamellar lyotropic mesophases in water. But there is an energy cost to bending of lipid layers, called the curvature elastic energy. Although the functional form of this energy is known, a complete quantitative knowledge of the curvature elastic energy, which is central to predicting the relative stability of the large number of phases that lipid membranes can adopt, has been lacking. Here we use X-ray synchrotron diffraction measurements of the variation of lattice parameter with pressure and temperature for the periodic Ia3d (Q230) cubic phase of hydrated monoolein to calculate the complete curvature elastic-energy function for the lipid cubic mesophase. This allows us to predict the stabilities of different cubic and lamellar phases for this system as a function of composition.

The neutral area surface of the cubic mesophase: location and properties

A neutral area surface can be defined as one whose area remains fixed upon bending. It is assumed that such a surface exists within the amphiphilic monolayers that constitute the bicontinuous cubic mesophases and that it parallels approximately the highly convoluted polar/apolar interface in such systems. Here, we report on how the neutral area surface in the cubic phase (space group Ia3d) of the hydrated monoacylglycerol, monoolein, was determined. It is located at a distance of approximately 8.8 A from the methyl terminus of the acyl chain. At 25 degrees C, the surface area per lipid molecule at the neutral area surface is 35.1 +/- 0.2 A2, which is remarkably similar to the mean cross-sectional area of hydrated monoolein in the lamellar liquid crystalline phase at this same temperature.

Non-steroidal anti-inflammatory drug and endotoxin induced uveitis

Suprofen eye drop was instilled into one eye of 10 pigmented rabbits and then anterior uveitis was induced by intraperitoneal injection of endotoxin of Shigella flexneri serotype 1A to evaluate the effects of non-steroidal anti-inflammatory drug on endotoxin induced uveitis. The pupillary diameters were measured, and aqueous cell and flare gradings were recorded in 20 eyes of 10 rabbits for one week at an interval of 12 hours for the first 24 hours and then every 24 hours for a week. A difference between the treated and control groups were investigated. All the above parameters showed greatest changes at 12 or 24 hours after injection and became normal by one week. The two groups demonstrated statistically significant difference at 12 hours, day 1 and day 2 as for pupillary diameter, at day 1 and day 2 as for cell and at 12 hours and day 1 as for flare. Thus, it can be concluded that prostaglandins play a role in miosis, in the appearance of inflammatory cells and flare in endotoxin induced uveitis and the topical administration of non-steroidal anti-inflammatory drug can alleviate signs of anterior uveitis. Specific relationship between leukotriene B4 and aqueous cell was not demonstrated.

Relationship between NMR transverse relaxation, trabecular bone architecture, and strength

Structure, biomechanical competence, and incremental NMR line broadening (R'2) of water in the intertrabecular spaces of cancellous bone were examined on 22 cylindrical specimens from the lumbar vertebral bodies of 16 human subjects 24-86 years old (mean, 60 years old). A strong association (r = 0.91; P < 0.0001) was found between Young's modulus of elasticity and R'2 for a wide range of values corresponding to cancellous bone of very different morphologic composition. NMR line broadening is caused by the inhomogeneity of the magnetic field induced as a consequence of the coexistence of two adjacent phases of different diamagnetic susceptibility--i.e., mineralized bone and water in the marrow spaces. Structural analyses performed by means of NMR microscopy and digital image processing indicated that the variation in R'2 is closely related to the trabecular microstructure. Mean trabecular plate density measured along the direction of the magnetic field was found to play a major role in predicting R'2 (r = 0.74; P < 0.0001). This behavior was confirmed when the plate density was varied in individual specimens, which was achieved by rotating the specimen, making use of the bone's structural anisotropy. It is concluded that the NMR transverse relaxation rate in human cancellous bone of the spine is significantly determined by trabecular structural parameters relevant to biomechanical strength. The results further underscore the important role played by the transverse trabeculae in contributing to cancellous bone strength. The work has implications on possible in vivo use of quantitative magnetic resonance for the assessment of fracture risk in osteoporotic patients.

High-resolution variable flip angle 3D MR imaging of trabecular microstructure in vivo

Two conceptually related variable-flip-angle 3D spin-echo pulse sequences were designed for imaging at voxel sizes of 2-5 x 10(-3) mm3 corresponding to pixel areas of less than 100 x 100 microns2 and section thicknesses on the order of 300-400 microns on a conventional 1.5 T MR imaging system equipped with 1 G/cm imaging field gradients, providing 12 sections in 10 min imaging time. The pulse sequences make use of the concept of restoring longitudinal magnetization inverted by the 180 degrees phase reversal pulse and are derivatives of pulse sequences previously dubbed "FATE" and "RASEE." It is shown that even in the small-voxel regime (< 10(-2) mm3 voxel size) and at echo times on the order of 10 ms, gradient echo images are sensitive to intrinsic fields causing artifactual boundary effects, including signal loss from intravoxel phase scrambling and spatial mismapping. At this resolution the variable flip-angle spin-echo pulse sequences are demonstrated to be better suited for imaging magnetically heterogeneous systems such as trabecular bone microstructure in vivo. These pulse sequences are found to be substantially less sensitive to distortions from magnetic dipole fields occurring at the boundaries of two phases of different magnetic permeability.

Bioavailability and disposition kinetics of HI-6 in Beagle dogs

The absorption and disposition kinetics of HI-6 were determined in Beagle dogs given single doses (25 mg kg-1) of the drug by the intravenous, intramuscular, and oral routes. Concentrations of the oxime in plasma and urine were measured by HPLC. A two-compartment open model was used to describe the disposition curve following intravenous drug administration while a one-compartment open model with first-order absorption adequately described the data following intramuscular or oral administration of the dose. Extravascular distribution of HI-6 was limited (Vss 203 ml kg-1) and the drug was eliminated rapidly after intravenous administration (t1/2 46.5 min, MAT 55.4 min). Systemic clearance was 3.68 ml min-1 x kg. A major fraction of the dose (63.7 per cent) was excreted in urine over a 24-h collection period. Following intramuscular drug administration, the absorption half-life (t1/2(a), 5.3 min), MAT (17.1 min), Cmax (70.37 micrograms ml-1) and tmax (15.9 min) indicate that the drug was rapidly absorbed. Systemic availability was 83.43 per cent after oral drug administration, absorption was preceded by a lag time (23.2 min). The t1/2(a) (41.5 min), MAT (81.6 min), Cmax (4.30 micrograms ml-1) and Tmax (90.6 min) indicate somewhat delayed absorption. Systemic availability (11.38 per cent) and the fraction of dose excreted unchanged in the urine (9.3 per cent) show that the drug was poorly absorbed. The apparent half-life (58.0 min) and MRT (137.6 min) following oral administration were significantly longer (p < 0.05) than following intravenous or intramuscular administration suggesting that the rate of absorption from the gastrointestinal tract decreases the elimination rate of the drug. In conclusion, HI-6 has limited distribution within the body, is rapidly eliminated mainly by renal excretion unchanged in the urine, and the bioavailability (i.e. rate and extent of absorption) of the drug varies with the route of administration.

Direct correlation of structure changes and thermal events in hydrated lipid established by simultaneous calorimetry and time-resolved x-ray diffraction

In many lipid systems, polymorphic and mesomorphic behavior depends on sample thermal history. To establish unequivocally the structural origin of endothermic and exothermic events in such systems, we have performed simultaneous calorimetry and time-resolved x-ray diffraction (SCALTRD). To this end, aluminum calorimetry crucibles were used to contain the hydrated lipid sample, and the calorimeter was mounted with the base of the crucible oriented perpendicular to a synchrotron-derived focused monochromatic x-ray beam for SCALTRD data collection. Measurements were made with hydrated monoelaidin and 1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine (DEPE) contained in hermetically sealed crucibles. Time-resolved x-ray diffraction (TRXRD) data were collected using an x-ray image intensifier/video system and a streak camera containing an x-ray sensitive image plate and/or film. SCALTRD analysis of the lamellar gel to lamellar liquid crystalline phase transition in hydrated monoelaidin gives identical progress curves by calorimetry and TRXRD at a scan rate of 1 degree C/min. At faster rates, calorimetry shows a broader phase transition that starts at a lower and ends at a higher temperature than is observed by TRXRD. The disparity arises in part because the x-ray beam used in TRXRD interrogates only a small portion of the sample, whereas the calorimeter responds to the entire sample volume. Because data collection times are relatively long, radiation damage is an important potential problem for SCALTRD measurements. Such an effect was observed with DEPE/water in that TRXRD shows the lamellar gel to lamellar liquid crystalline phase transition occurring at a lower temperature than observed by calorimetry. We speculate that the sample accumulates impurities locally as a result of radiation damage that has the effect of lowering the phase transition temperature at the site of interrogation by the x-ray beam. This "methods-in-combination" SCALTRD approach facilitates the direct correlation of structure rearrangements and thermal events in the same sample under identical conditions of thermal history. The information content of the data so derived far surpasses that available from either method used in isolation.

Immunopathology of experimental autoimmune uveoretinitis in primates

The eyes and pineal glands from 10 monkeys immunized with S-antigen were studied using routine histopathological and immunohistochemical techniques. Seven out of 10 animals developed uveitis between 19 and 33 days after the initial immunization. Histopathology of the eyes harvested 70 days after immunization showed moderate to marked uveoretinitis, subretinal fibrosis, retinal necrosis and gliosis. The pineal glands demonstrated chronic pinealitis. The infiltrating cells were both CD3 and CD19/CD22 lymphocytes with a ratio of 1.4 in the eye and 2.2 in the pineal gland. The ratio of CD4 to CD8 lymphocytes was 1.5:1. MHC Class II antigens and adhesion molecule (ICAM-1) were observed on resident cells. The influx of B lymphocytes and the formation of subretinal fibrosis differentiate the disease in the monkey from that in the rat and mouse. These findings are similar to Vogt-Koyanagi-Harada syndrome and subretinal fibrosis with uveitis syndrome in human.

Distribution of prostaglandin E2 in gastric and duodenal mucosa: possible role in the pathogenesis of peptic ulcer

BACKGROUND

Prostaglandin E which is present abundantly in the gastric mucosa is a powerful inhibitor of gastric acid secretion and a stimulus to gastric mucus production. In addition, prostaglandin E2 inhibits ulcer formation in animals, and the synthetic analogues of prostaglandin E have successfully been used in the treatment of patients with gastric and duodenal ulcer disease. To evaluate the role of endogenous prostaglandin E2 in the pathogenesis of the peptic ulcer disease, we measured mucosal prostaglandin E2 levels in patients with gastric and duodenal ulcer disease and compared with that of non-ulcer control persons.

METHODS

The study population was made up of 44 non-ulcer persons, 36 patients with a benign gastric ulcer, and 48 with a duodenal ulcer. Every mucosal specimen, taken from the antrum and from the duodenal bulb, were homogenized, mixed with 1 M HCl, and centrifuged. After removal of the supernatant, precipitate was eluted with ethyl acetate in the Amprep C18 minicolumn. Then the extracted prostaglandin E2 in the ethyl acetate fractions was converted into its methyl oximate derivatives, and the prostaglandin E2 level was measured by radioimmunoassay. During the procedure any homogenized specimen which was looking grossly bloody was removed from the assay in order to avoid any possible contamination or prostaglandin E2 in blood.

RESULTS

In non-ulcer persons, the mean values was 258.17 +/- 127.03 pg/mg. tissue in antrum and 121.07 +/- 67.46 pg/mg. tissue in duodenal bulb. The corresponding values were 186.42 +/- 70.51 pg/mg. tissue, 79.44 +/- 39.04 pg/mg. tissue in gastric ulcer patients and 204. 94 92.03 pg/mg. tissue, 99.66 +/- 56.10 pg/mgl. tissue in duodenal ulcer patients respectively. Gastric ulcer patients have the significantly lower level of the antral and duodenal prostaglandin E2 (p < 0.005). Those levels of duodenal ulcer patients were also significantly lower than those of non-ulcer persons (p < 0.025 & 0.05). Antral prostaglandin E2 level increased to 305.21 +/- 104.91 pg/mg. tissue in the gastric ulcer patients (p < 0.005) and to 271.02 +/- 93. 23 pg/mg. tissue in the duodenal ulcer (p < 0.005) when the ulcer crater was healed. The duodenal bulb prostaglandin E2 level was also increased in the healed stage of ulcer, e. g., 128.84 +/- 57.62 (p < 0.005) and 112.60 +/- 42.25 pg/mg. tissue, respectively.

CONCLUSION

These results suggest that prostaglandin deficiency in the antral and duodenal bulb mucosa may have an important role in the pathogenesis of peptic ulcer disease.

Cellular components of proliferative vitreoretinal membranes

To understand the pathogenesis of proliferative vitreoretinal membrane formation which occurs in proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR), etc., accurate identification of the cellular components of the membrane is needed. This study was performed to identify cellular components of the membranes by means of immunohistochemical technique. 11 proliferative vitreoretinal membranes which were surgically obtained from 7 eyes with PVR and 4 eyes with PDR were stained with monoclonal antibodies against cytokeratin, glial fibrillary acidic protein (GFAP), or vimentin using immunoperoxidase technique (ABC method). In the PVR membranes, mean cell positivities for cytokeratin, GFAP and vimentin were 48%, 1% and 92%, respectively and in the PDR membranes, 0%, 5% and 93%, respectively. The above results suggest that retinal pigment epithelial cells and fibroblasts are major cellular components of PVR membranes, and that mesenchymal cells are major cellular components and glial cells are minor cellular components of PDR membranes.

Dermal absorption of niclosamide in rats and minipigs

The dermal absorption of niclosamide, a drug shown to prevent Schistosomiasis by blocking the dermal penetration of cercariae, has been examined in Sinclair minipigs and rats. Radioactivity in the urine and feces collected daily for 7 days after application of 14C-niclosamide accounted for less than 2 per cent and 10 per cent of the labelled compound applied to pig and rat skin, respectively. Approximately 20 per cent of the radioactivity from the dose solution was recovered on the skin excised from the area of application in both minipigs and rats. No radioactivity was detected in organs removed from the pig 7 days after application of radiolabelled drug while less than 6 per cent of the dose could be accounted for in the rat organs/carcass. Radioactivity in swine blood, removed 0.5, 1, 2, 4 and at 24 h intervals after dosing, was at or below three times background in all of the samples. Total recovery of the applied radioactivity was 78 per cent in pigs and 57 per cent in rats. These studies indicate that niclosamide is very poorly absorbed after dermal application. The results are consistent with earlier comparative studies showing that dermal penetration of xenobiotics in rats is generally higher than in swine.

Pharmacokinetics of pyridostigmine in dogs

The pharmacokinetics of the cholinesterase inhibitor pyridostigmine has been studied in six male Beagle dogs after iv infusion and after oral doses as an immediate-release syrup and as an extended-release tablet, all at a level of approximately 0.6 mg/kg. Pyridostigmine was characterized as a drug of relatively long terminal half-life (8.3 h +/- 2.1 SD), low systemic clearance (13 mL/min/kg +/- 1 SD) and high volumes of distribution (Vd lambda z, 8.7 L/kg +/- 1.9 SD and Vdss, 3.9 L/kg +/- 0.9 SD). The ratio of mean residence times in tissues and plasma was greater than 4, indicating a high affinity of peripheral tissues for the drug. This ratio was about twofold higher in three of the dogs than in the others. Pyridostigmine was slowly and incompletely bioavailable in these dogs; the systemic availability was 44.4% +/- 4.3 SD from the syrup and 33.6% +/- 9.5 SD from the tablet. Pyridostigmine disposition in these dogs was largely determined by distribution processes.

[Clinical application of intermaxillary traction for temporomandibular disorders]

Occlusal splint has been usually used for TMJ arthrosis as a conservative treatment, but the range of its application is narrow and less effective. This study is to evaluate the effect of the pivoting splint with intermaxillary rubber traction, to report the results of the pivoting splint with intermaxillary rubber traction which was used 24 patients.

Pharmacological and toxicological evaluation of orally administered pyridostigmine in dogs

Pyridostigmine bromide, a reversible cholinesterase inhibitor, was administered orally (capsule gavage) to beagle dogs (10-15 months of age) of both sexes once daily at 5, 10, or 20 mg/kg for 14 days; every 8 hr at 2 or 5 mg/kg for 28 days; or every 8 hr at 0.05, 0.5, or 2 mg/kg for 3 months as part of its preclinical safety assessment. A small portion of the dogs receiving pyridostigmine for 3 months were allowed an untreated recovery period of an additional 3 months. Daily doses of 10 or 20 mg/kg were lethal to some of the dogs when given for up to 14 days and caused severe intestinal distress, including diarrhea, emesis, and reddened feces in all animals. The cause of death was intestinal intussusception. Signs of systemic toxicity apparent at these doses included hypersalivation and tremors. Similar but less severe effects were produced by 5 mg/kg per day; plasma cholinesterase activities were inhibited by all three doses in a dose-related manner. Signs of toxicity in the 28-day and 3-month studies were generally limited to the gastrointestinal tract and included diarrhea or soft stools and reddened or mucoid-containing stools; these signs appeared to reverse upon discontinuation of the drug. A single dog at 2 mg/kg every 8 hr developed an apparent intussusception. There were no pathological changes in clinical chemistry, hematology, or urinalysis parameters associated with doses of 0.05, 0.5, or 2 mg/kg every 8 hr for up to 3 months, nor were any drug-related lesions observed upon gross necropsy and microscopic evaluation of the major tissues and organs. Red blood cell (RBC) acetylcholinesterase (AChE) activities in the 3-month study were inhibited by approximately 10, 50, and 70% in the 0.05, 0.5, and 2 mg/kg every 8-hr dose groups, respectively, and these degrees of inhibition were maintained throughout the period of treatment. These data suggest that prolonged oral administration of pyridostigmine at doses sufficient to cause profound and sustained inhibition of RBC AChE activity (i.e., as high as 70%) cause mainly local, gastrointestinal distress related to altered intestinal motility. At the extreme, this can be manifested as a life-threatening intestinal intussusception. Systemic anticholinesterase effects (other than enzyme inhibition) were observed only at doses of 2 mg/kg and greater, while local (gastrointestinal) effects and inhibition of RBC AChE were observed at doses as low as 0.05 mg/kg.

[Arthroscopic surgery for habitual dislocation of the temporomandibular joint]

This study is to evaluate the effect of the arthroscopic surgery for habitual dislocation of the temporomandibular joint. Conclusively, it is believed that arthroscopic surgery for habitual dislocation of the temporomandibular joint is easier method, has fewer complications, and lower recurrence rate, when compared with the conventional temporomandibular joint surgery.

Detection of 3,4-dihydroxyphenylglycolaldehyde in human brain by high-performance liquid chromatography

The monoamine oxidase A metabolite of noradrenaline, 3,4-dihydroxyphenylglycolaldehyde, is the precursor of 3,4-dihydroxymandelic acid, and 3,4-dihydroxyphenylglycol, metabolites of noradrenaline. Owing to difficulties in purifying this aldehyde, it has not been previously characterized or identified in biological sources. This paper describes an enzymatic synthesis, purification, and characterization of 3,4-dihydroxyphenylglycolaldehyde. The aldehyde metabolite is identified in postmortem human brain using high-performance liquid chromatography and electrochemical detection. We estimate the concentration in human hippocampus to be 0.164 +/- 0.05 nmol/g. The importance of this aldehyde metabolite of noradrenaline is discussed.

The effect of cryotherapy on proliferative vitreoretinopathy (PVR)

Cryotherapy is implicated for inducing or aggravating proliferative vitreoretinopathy (PVR) by releasing retinal pigment epithelial (RPE) cells. These are based on the fact that PVR rarely occurs in a non-operated eye, and many of the PVR patients have received cryotherapy during surgery. Nonetheless, eyes with diathermy also developed PVR, and although there have been many experiments, the effect of cryotherapy on inducing PVR has not been proven experimentally in the living eye. We made retinal tears in living rabbit eyes, and applied cryotherapy on one eye of each rabbit. The result was compared histologically with the contralateral noncryothermized control eye. There was no statistically significant difference between the two groups concerning the migration of RPE, and the proliferation of RPE. Although the formation of an epiretinal membrane was more obvious in the cryothermized group, the difference was not statistically significant.

Chorioretinal disease patterns in congenic mice following intraocular inoculation with HSV-1

Disease patterns and immunologic parameters were studied employing inbred and Igh-1 disparate congenic mice to determine the role of host genetics and Igh-1-linked gene products in the von Szily model of viral chorioretinitis. Following intracameral inoculation of 1.5 x 10(4) PFU HSV-1 (KOS), 100% of BALB/c (Igh-1a), 62% of A/J (Igh-1e) and none of the C57BL/6J (Igh-1b) inbred mice developed contralateral necrotizing chorioretinitis. Multigenic differences between inbred mice prohibit conclusions about the specific role of Igh-1-linked immune regulation in this model. In order to more exactly define Igh-1-specific restriction of HSV-1-mediated chorioretinitis, Igh-1-disparate, congenic BALB/c mice were studied following both anterior chamber and intravitreal inoculation protocols. Anterior chamber inoculation resulted in contralateral retinal necrosis in 75% of BALB/c (Igh-1a) mice, 30% of C.AL-20 (Igh-1d) and 5% of the C.B-17 (Igh-1b) congenic mice; all strains showed ipsilateral retinal sparing. Following intravitreal inoculation of HSV-1 a similar restricted disease pattern was found in contralateral eyes. Contralateral chorioretinitis developed in 30% of BALB/c, 15% of C.AL-20 and 6% of C.B-17 mice. Ipsilateral disease, however, was found in all murine strains. These disease patterns developed despite equivalent suppression of systemic DTH and equivalent RPE permissivity to viral replication. These data demonstrate that host genetics strongly regulates contralateral HSV-1-mediated chorioretinal disease patterns by a mechanism unrelated to the development of systemic suppression of DTH and specifically support a dominant role for gene products linked to the Igh-1 locus in the immunomodulation of ocular disease.

Clinical analysis of uveitis

Uveitis can be classified in a variety of ways and this fact makes it difficult to compare results. Therefore we classified uveitis by the location with the method of Henderly; anterior-, posterior-, intermediate- and panuveitis. We determined the frequency of occurrence, etiology and clinical characteristics of various forms of uveitis. We conducted a retrospective analysis of 683 patients with uveitis seen at Seoul National University Hospital from January 1978, to December 1987. The results were as follows. 1. 192 cases (28.1%) occurred as anterior uveitis, 218 cases (31.9%) as posterior uveitis, 166 cases (24.3%) as panuveitis and 107 cases (15.7%) as pars planitis. Posterior uveitis was the most common form of uveitis. 2. In cases of anterior uveitis, 142 cases (74.0%) were idiopathic, traumatic uveitis was seen in 18 cases. In posterior-uveitis, 111 cases (50.9%) were idiopathic, retinal vasculitis including Eales' disease in 60 cases (27.5%), toxoplasmosis in 23 cases (10.6%). In cases of panuveitis, idiopathic form occurred in 80 cases (48.2%), Behçet's disease in 41 cases (24.7%). The idiopathic form was the most common entity in all locations of uveitis.

Comparative evaluation of caffeine and theophylline for weaning premature infants from the ventilator

Expedient weaning of infants from the respirator minimizes the risk of complications associated with assisted ventilation. Since theophylline and caffeine decrease apnea and enhance respiratory effort, we conducted a blinded, randomized comparative evaluation of each drug to determine extubation time and incidence of reintubation. Forty-five clinically stable premature infants receiving mechanical ventilation on minimal settings randomly were assigned to receive either theophylline (n = 23) or caffeine (n = 22) at least 1 day before and 5 days after extubation. From study entry to extubation, the mean number of days was 2.7 for both theophylline- and caffeine-treated infants. Three theophylline- and three caffeine-treated infants developed respiratory failure necessitating reintubation (NS). These findings indicate that for premature infants on minimal respiratory settings, the duration of intubation and the incidence of reintubation after treatment with theophylline or caffeine were similar.

BCNU in silicone oil in proliferative vitreoretinopathy: I. Solubility, stability (in vitro and in vivo), and antiproliferative (in vitro) studies

Various pharmacologic agents have been tried to control proliferative vitreoretinopathy (PVR). However, most are water soluble and cannot be used with silicone oil (SO), a tamponade agent also used in PVR management. We evaluated a lipophilic, antiproliferative drug, BCNU, in regard to its solubility and stability in SO, its release from SO into an aqueous solution, and its effect on cell cultures. BCNU is soluble in SO (peak concentration in micrograms/ml 1020, 750, and 294 at 37 degrees C, 21 degrees C, and 4 degrees C, respectively), and stable (half-life = 6.7 weeks at 37 degrees C, 17.9 weeks at 21 degrees C). At 4 degrees C, no significant decrease in concentration up to eight weeks was noted. BCNU is released from SO to water (partition coefficient = 10.28 +/- 2.16). Its median inhibitory doses (ID50) on bovine retinal pigment epithelial (RPE), rabbit RPE, and subconjunctival fibroblast cells are 13, 1.9, and 15.6 micrograms/ml, respectively. BCNU may be a useful pharmacologic tool to control PVR.

Reevaluation of corneal complications after closed vitrectomy

Corneal complications after closed vitrectomy were analyzed in patients treated by the same surgeon from January 1980 through December 1986. Of 428 eyes (400 patients), 64 (15%) had corneal complications, 58 (13.6%) had epithelial defects, and 12 (2.8%) had corneal edema. Among 206 diabetic eyes, 41 (19.9%) had corneal complications. Of 222 nondiabetic eyes, only 23 (10.4%) showed complications. Multiple regression analysis of possible contributing factors was performed. Diabetes, intraoperative lensectomy, and history of vitreous surgery were related significantly to the occurrence of all corneal complications combined. Our series showed a significantly decreased complication rate when compared with a previous study. Improved preoperative surgical preparation and intraoperative technique to minimize corneal trauma may have accounted for the decrease.

Extraction of retinol and cholesterol by intraocular silicone oils

According to their solubility parameters, retinol and its derivatives, as well as cholesterol and other lipophilic substances, are predicted to dissolve in intraocular silicone and fluorosilicone oils. Calf retinas were extracted in vitro with these oils and the oils then analyzed spectrophotometrically. The following levels were found after extraction for 4 and 48 hours, respectively: for retinol, silicone oil, 0.5 and 3.7 micrograms/ml, and fluorosilicone oil, 0.5 and 3.3 micrograms/ml; for cholesterol, silicone oil, 0.5 and 6.4 micrograms/ml, and fluorosilicone oil, 0.8 and 3.7 micrograms/ml. In in vivo experiments, intraocular oils were removed from rabbit eyes at 4 days to 10 weeks after injection. The retinol levels were 1.7 to 11.4 micrograms/ml in silicone oil and 2.4 to 7.3 micrograms/ml in fluorosilicone oil; the cholesterol levels were 2.7 to 12.6 micrograms/ml in silicone oil and 7.5 to 15.6 micrograms/ml in fluorosilicone oil. Fluorosilicone and silicone oils (1000 cs) removed from human eyes at 7.3 and 102.0 weeks postoperatively had a retinol content of 5.4 and 2.9 micrograms/ml, respectively. Silicone oil of 1000 cs removed from a patient 51 weeks postoperatively and silicone oil of 12,500 cs removed 96 weeks postoperatively gave reaction characteristics for cholesterol, 230 and 99 micrograms/ml, respectively.

Long-term treatment of anxiety and risk of withdrawal. Prospective comparison of clorazepate and buspirone

Risk of withdrawal was investigated in a prospective, double-blind comparison of clorazepate dipotassium, a benzodiazepine with a long half-life, and the nonbenzodiazepine buspirone hydrochloride in the long-term treatment of anxious outpatients. Patients were treated with therapeutic doses of clorazepate dipotassium (15 to 60 mg/d) or buspirone hydrochloride (10 to 40 mg/d) for six continuous months before their tranquilizer therapy was blindly and abruptly stopped. There was a significant increase in symptom severity consistent with a withdrawal reaction for the clorazepate group but not the buspirone group. For the clorazepate group, there was a suggestion that previous discontinuous exposure to benzodiazepines might sensitize patients to subsequent withdrawal effects. For the buspirone group, a higher dropout rate raised questions about patient satisfaction with therapy in this rather chronically anxious population.

Methemoglobin formation resulting from administration of candidate 8-aminoquinoline antiparasitic drugs in the dog

In vivo methemoglobin (MHb) formation caused by five 8-aminoquinoline compounds was tested in beagle dogs. Male beagle dogs were dosed orally once per day at 0.0116 mmol/kg for 4 consecutive days with primaquine (8-[4-amino-1-methylbutyl)amino]-6-methoxyquinoline, diphosphate), three candidate 8-aminoquinoline antimalarial drugs (WR 225,448 5-(3-trifluoromethyl)phenoxy-4-methyl primaquine, succinate); WR 238,605 2,6-dimethoxy-5-(3-trifluoromethyl)phenoxy-4-methyl primaquine, succinate; or WR 242,511 5-hexoxy-4-methyl primaquine, diphosphate dihydrate), or a candidate 8-aminoquinoline antileishmanial drug WR 6026 (8-[(6-diethylamino)amino]-6-methoxy-4-methyl quinoline, dihydrochloride). MHb and total hemoglobin levels were determined daily prior to dosing and for 29 days after drug administration. All compounds caused prolonged levels of MHb that peaked at Days 4 to 5 with disappearance half-lives of 5 to 9 days. Peak percentage MHb of primaquine, WR 6026, WR 238,605, WR 225,448, and WR 242,511 was 6.3, 20.7, 16.0, 25.3, and 48.1%, respectively. Total MHb as measured by area under the time-concentration curve was highest for WR 242,511, followed by WR 225,448, WR 238,605, WR 6026, and primaquine, respectively. The results of this study, in conjunction with other toxicity and efficacy studies, have been utilized to select one of these compounds for development as a replacement for the antimalarial drug primaquine, and also to characterize the MHb-forming properties of WR 6026.

Effectiveness of silicone oil removal from rabbit eyes

Silicone oil (1000 and 12,500 cs) and fluorosilicone oil (1000 and 10,000 cs) were dyed red and injected into a gas-created space in the vitreous cavity of 51 rabbit eyes. Later the oils were removed from the vitreous cavity either by lavage with balanced salt solution (group 1, 27 eyes) or by injecting a sodium hyaluronate solution, followed by lavage with balanced salt solution (group 2, 24 eyes). The average amount of oil retained in the vitreous cavity in group 1 was 0.0675 ml, and occasionally a large amount of oil was found (more than 0.1 ml in 30% of eyes). The average amount of oil retained in group 2 was 0.0114 ml, and no eye retained more than 0.1 ml of oil. The difference between the two groups was statistically significant (p less than 0.02), but there was no significant difference in oil retention within either group between the different kinds of oils, or between different viscosities of oil. The data suggest that residual oil can persist in the vitreous cavity despite thorough lavage, and that removal of silicone oil with the use of a sodium hyaluronate solution significantly lowers the risk of a large amount of residual silicone oil that is occasionally seen with conventional removal methods.

Irreversible inhibition of the human placental NADP-linked 15-hydroxyprostaglandin dehydrogenase/9-ketoprostaglandin reductase by glutathione thiosulfonate

Oxidation of glutathione disulfide by a mixture of performic and hydrochloric acids leads to the formation of several compounds that are stronger inhibitors than glutathione disulfide of the placental enzyme that possess both NADP-linked 15-hydroxyprostaglandin dehydrogenase and 9-ketoprostaglandin reductase activities. The only one of these inhibitors that has been identified is glutathione thiosulfonate. The others are unstable and may include glutathione sulfinyl sulfone and glutathione disulfone. Since the enzyme appears to have a glutathione binding site in close proximity to its active site and glutathione thiosulfonate reacts with free sulfhydryl groups, the effects of this thiosulfonate on the enzyme were examined in more detail. Glutathione thiosulfonate and methyl methanethiosulfonate cause a time-dependent irreversible inhibition of both the hydroxyprostaglandin dehydrogenase and the ketoprostaglandin reductase activities, presumably by reacting with a free sulfhydryl at the prostaglandin binding site. Experiments with PGA1-glutathione show that this sulfhydryl is not necessary for the catalytic activity of the enzyme as long as the substrate can bind at the glutathione site.

Glutathione mixed disulfide inhibitors of the human placental NADP-linked 15-hydroxyprostaglandin dehydrogenase

Six glutathione-containing inhibitors of the human NADP-linked 15-hydroxyprostaglandin dehydrogenase have been isolated from placental homogenates. Glutathione disulfide is one of these inhibitors. Although the structures of the other five have not been fully elucidated, all are disulfides. Studies with these compounds and with other mixed disulfides have shown that the glutathione mixed disulfides of beta-mercaptopyruvate, mercaptoacetate, and beta-mercaptolactate are more effective inhibitors of the enzyme than are the glutathione-containing mixed disulfides isolated from placental homogenates. beta-Mercaptolactate is particularly noteworthy because of its low Ki (0.13 microM). The results reported here suggest that the activity of the prostaglandin dehydrogenase may be influenced in vivo by various glutathione mixed disulfides.

Analysis of artesunic acid and dihydroqinghaosu in blood by high-performance liquid chromatography with reductive electrochemical detection

A new high-performance liquid chromatography (HPLC) method using reductive electrochemical detection has been developed for the analysis of the antimalarial drugs artesunic acid (ARTS) and dihydroqinghaosu (DQHS) in blood. Presently, this method has been validated to 4 micrograms/ml for ARTS and 200 ng/ml for DQHS. Pharmacokinetic studies in the rabbit show that after intravenous administration (100 mg/kg) ARTS is metabolized rapidly to DQHS and has a t1/2 of 1.7 min in blood. DQHS data were fit to non-linear regression models consisting of the sum of two exponential terms. For phases 1 and 2, t1/2 values of 3.0 +/- 0.4 and 29 +/- 2 min were calculated, respectively. In vitro studies in which ARTS was incubated with blood from various species show that rabbit blood hydrolyzes ARTS at a much greater rate than rat or human blood. Incubation of ARTS with rabbit blood in the presence or absence of diisopropylfluorophosphate suggested that this hydrolysis reaction is catalyzed by plasma and red blood cell esterases. These results suggest that future pharmacokinetic studies in both animals and man should focus on the measurement of DQHS rather than ARTS.

Use of high-density fluorosilicone oil in open-sky vitrectomy

During prolonged open-sky vitrectomy, fluid accumulates in the suprachoroidal and subretinal spaces and the resultant ballooning of the choroid and of the retina interferes with the surgery. Fluorosilicone oil (polymethyl-3,3,3-trifluoropropylsiloxane) with a specific gravity of 1.28 was tested for use as a temporary vitreous substitute during open-sky vitrectomy. After open-sky vitrectomy and bullous retinal detachment in pigmented rabbits, fluorosilicone oil flattened the retina completely in nine of nine eyes, whereas 1% sodium hyaluronate solution flattened the retina completely in only four of nine eyes. The flattening effect of fluorosilicone oil on the retina was also better than that of 1% sodium hyaluronate in an experiment with retinal detachment and giant retinal tear after open-sky vitrectomy.

Structure-activity relationships of putative primaquine metabolites causing methemoglobin formation in canine hemolysates

A rapid and reproducible in vitro test system was developed to measure the methemoglobin (MHb)-forming properties of various 8-aminoquinoline derivatives. Initial rates and extents of reaction were measured spectrophotometrically with either canine hemolysates from which ferrihemoglobin reductase was removed, or with purified human oxyhemoglobin (Hb). The results demonstrate that primaquine derivatives that can be oxidized to quinones or iminoquinones (5-hydroxy,6-desmethyl primaquine; 5-hydroxyprimaquine; 5,6-dihydroxy-8-aminoquinoline; and 5-hydroxy, 6-methoxy-8-aminoquinoline) are potent MHb-forming compounds. Studies on the extent of reaction in hemolysates and purified oxyhemoglobin suggest that the extent of MHb formation may be limited by the rate at which the corresponding iminoquinones or quinones arylate nucleophiles. The effects of glutathione, mannitol, ascorbate, and superoxide dismutase on the rate and extent of hemoglobin oxidation by 5,6-dihydroxy-8-aminoquinoline suggest that these compounds oxidize Hb similar to the mechanism known for dimethylaminophenol (DMAP), in which Hb oxidizes the quinoline to semiquinone radical and quinone species which are the oxidizing and arylating agents.

Six-week trial with diazepam: some clinical observations

Side effects, improvement, and predictors of response were examined in 295 patients treated for greater than or equal to 1 week with diazepam; 234 of these patients completed 6 weeks of treatment. The greatest improvement occurred during the first week of treatment. Sedation was the predominant side effect. Predictors of improvement included low educational level, lack of previous treatment, presence of precipitating stress, low occupational and/or family adjustment, low levels of trait anxiety, and high levels of state anxiety.

Metabolism of a potential 8-aminoquinoline antileishmanial drug in rat liver microsomes

The metabolism of the 8-aminoquinoline, 8-(6-diethylaminohexylamino)-6-methoxy-lepidine dihydrochloride (WR 6026 X 2HCl), was studied in a rat hepatic microsomal system. The results show that WR 6026 X 2HCl was metabolized into two more polar compounds. The structures of these metabolites as proven by gas chromatography-mass spectrometry, ultraviolet absorption, and high performance liquid chromatography were: 8-(6-ethylaminohexylamino)-6-methoxy-lepidine (metabolite 1) and 8-(6-diethylaminohexylamino)-6-methoxy-4-hydroxymethyl quinoline (metabolite 2). The formation of both metabolites was NADPH dependent and also linearly dependent on incubation time and microsomal protein concentration at 0.24 mM WR 6026 X 2 HCl. Studies on the effects of pretreatment of animals with either phenobarbital or Aroclor 1254 suggest that cytochrome P-450 isozymes catalyzed both N-deethylation and hydroxylation reactions. N-deethylase activity was induced by either pretreatment: however, hydroxylase activity was unaffected by phenobarbital pretreatment and significantly elevated by Aroclor 1254 pretreatment. These results suggest that these two reactions are catalyzed by different cytochrome P-450 isozymes. The formation of these two metabolites in vivo may play an important role in the antileishmanial activity of WR 6026 X 2HCl.

High-performance liquid chromatographic method for the analysis of a candidate 8-aminoquinoline antileishmanial drug using oxidative electrochemical detection

An analytical method was developed for the quantitation of a candidate antileishmanial drug, 6-methoxy-8-(6-diethylaminohexylamino)-4-methylquinoline, dihydrochloride, in canine plasma. The assay utilized internal standard technique with a structural similar 8-aminoquinoline, 6-methoxy-8-(7-diethylaminoheptylamino)-4-methylquinoline, dihydrochloride, as the internal standard. The method employs a liquid-solid extraction procedure with prepackaged silica gel columns upon which the drug and internal standard are adsorbed, then selectively washed and eluted. Reversed-phase chromatography was then employed to analyze the extracted sample by means of oxidative electrochemical detection at +0.75 V. Good accuracy and precision were obtained over the range of concentration tested (10-1500 ng/ml plasma). Analyses of plasma samples from human volunteers given the drug demonstrate the method is also suitable for analysis of human plasma samples. The entire procedure is relatively simple and requires only 1 ml of plasma.

Deficiencies and improvement of methemoglobin assay

A day-to-day variability in results was encountered when using the Dubowski method for the routine clinical determination of methemoglobin in blood. Therefore, studies were performed to determine the source(s) of variability in the method as described by Dubowski. It was determined that complete lysing of red blood cells is dependent upon both temperature of the buffer and the amount of lysing agent. Low buffer temperatures (less than 14 degrees C) produced highly variable results. This variability can be reduced by increasing the level of lysing agent to 40 mg per 20 mL of diluted blood. It was found that by using 37 degrees C buffer solution temperature and 40 mg Triton X-100 as lysing agent per 20 mL of diluted blood (1:20 with 0.25M sodium phosphate buffer, pH 7.4), the precision (percent coefficient of variation = 2%) and the accuracy (percent coefficient variation = 5.5%) were excellent.

Gentamicin penetration into diseased appendix tissue

Gentamicin concentrations in appendix tissue, serum, and peritoneal fluid were obtained in suspected cases of gangrenous or perforated appendicitis. Despite widely ranging gentamicin concentrations, no infectious complications developed. Correlations were made between the pathologic state of the tissue and the tissue gentamicin concentrations. Correlations were also made with tissue gentamicin concentrations and the time after the antibiotic dose to the time of sampling.

The covalent structure of apolipoprotein A-I from canine high density lipoproteins

The complete amino acid sequence of apolipoprotein A-I (apo-A-I) from canine serum high density lipoproteins (HLD) has been determined by automated Edman degradation of the intact protein and proteolytic fragments derived therefrom. The major strategy involved analysis of overlapping sets of peptides generated by cleavage at lysyl residues with Myxobacter protease and by tryptic hydrolysis at arginines in the citraconylated protein derivative. Canine apo-A-I has 232 residues in its single polypeptide chain and its covalent structure is highly homologous to one of the two reported sequences for human apo-A-I. As in the case for the human apoprotein, predictive analysis of the canine apo-A-I sequence suggests that it comprises a series of amphiphilic alpha helices punctuated by a periodic array of prolyl residues. Human HDL contains a second major protein component, apolipoprotein A-II (apo-A-II) that is lacking in HDL from dog serum. The absence of apo-A-II in canine HDL raised the possibility that the apo-A-I from this source might contain within its primary structure sequences related to apo-A-II and thus perform the dual function of both proteins in one. Our analysis proves that canine apo-A-I has all of the structural features of human apo-A-I and that it is not an A-I: A-II hybrid molecule.

Disposition of the diastereoisomer of mefloquine in mice

The disposition of the diastereoisomer of mefloquine, WR 177,602 . HCl, was examined over a 168-hour period after 10 mg/kg of the 14C-labeled drug was administered orally to female albino ICR mice. This drug was absorbed readily. 2 h after dosing, the drug was distributed throughout the animal body with a large percent of the administered dose found in the eyes, submaxillary salivary glands, lungs, spleen, liver, gallbladder plus bile, kidney and carcasses. The elimination half-life of the unmetabolized WR 177,602 in plasma was estimated to be 16.1 h. The major route of excretion of the drug was via the feces (70%), with 23% in the urine 168 h. The elimination half-lives of the unmetabolized drug in urine and feces were 8.0 and 6.9 h, respectively. The disposition of WR 177,602 . HCl was similar to its erythrodiastereoisomer in female mice.

Sequence of the N-terminal half of Bacillus amyloliquefaciens alpha-amylase

Bacillus amyloliquefaciens alpha-amylase (1,4-alpha-D-glucan glucanohydrolase. EC 3.2.1.1), which is commercially supplied as 'Bacillus subtilis alpha-amylase' does not cross-react immunologically with B. subtilis alpha-amylase. This enzyme (from B. amyloliquefaciens) was cleaved by treatment with CNBr into seven fragments. Peptide A was selected for sequence determination. It is the longest one, containing 185 amino acids (i.e. approx. 50% of the total molecule) and connects to the hexapeptide of the N-terminus. Its primary structure was aligned by use of various proteolytic enzymes. The sequence of amino acids 181-184 is identical with that of amino acids 14-17 of the alpha-amylase isolated from B. subtilis (except that amino acid 183 is asparagine rather than aspartic acid).