Interlenticular opacification in piggyback AcrySof intraocular lenses: explantation technique and laboratory investigations

BACKGROUND/AIMS

Interlenticular opacification (ILO) is a recognised complication of piggyback intraocular lenses (IOLs). The aetiology, histopathology, and treatment are not clearly defined, however.

METHODS

Two pairs of AcrySof IOLs were explanted from a patient with bilateral ILO. The explantation technique and surgical challenges of IOL exchanges are described. The explanted IOL complexes and a sample of the anterior capsule were examined by phase, polarising, and immunofluorescence microscopy.

RESULTS

A 50 year old man developed ILO bilaterally after piggyback AcrySof IOL implantation. A central contact zone was surrounded by a homogeneous paracentral opacity possibly consisting of extracellular matrix previously laid down by proliferating lens epithelial cells (LECs). These opacities were in turn surrounded by interlenticular Elschnig pearl-type opacities contiguous with the same material filling the periphery of the capsular bag. The IOL complexes were very adherent to the capsular bag and they had to be separated with the help of high viscosity viscoelastic before a single one piece PMMA IOL implantation via large limbal incisions. The sample of anterior capsule showed a ridge configuration from the piling of LECs in the site of apposition with the anterior capsule and cells showing different characteristics on either side of the ridge.

CONCLUSION

Cellular proliferation, deposition of ECM from proliferating LECs, and capsular changes induced by cell metaplasia may lead to ILO formation in piggyback AcrySof IOLs. Careful separation of the AcrySof IOL complex from the capsule, meticulous clean up of the proliferating material, and implantation of single or dual in the bag PMMA IOLs through a large incision with capsulorrhexis enlargement may help in the prevention of recurrence of interface opacification.

Sectional neuroanatomy of the lower limb I: lower back and hip

This series of two articles is structured to provide anatomically accurate functional schematics of the motor and sensory innervation of the lower back, hip, and lower limb. This first paper provides radiographically oriented schematic axial sections of the lower back and hip in which the muscles are appropriately color-coded to match the peripheral nerves. A companion color-coded summary table allows prediction of unique patterns of denervation from 25 lesion sites. These are divided into three categories (roots T12 to S4, four plexal quadrants, and 11 sectional levels). Correlation between an imaging abnormality at one of these lesion sites and the predicted denervation pattern ensures the lesion is, in fact, clinically significant. The next article will continue this color-coded approach into the lower limb.

Reconciliation of the Anatomic, Surgical, and Radiographic Classifications of the Mediastinum

The mediastinum is a complex region that is variously subdivided by radiologists, surgeons and anatomists. This paper describes the most popular of these classifications and color-codes the radiologic and surgical divisions on 22 labeled axial sections of the chest. This allows the reader to quickly name the appropriate location of a lesion on any section.

FGF: an autocrine regulator of human lens cell growth independent of added stimuli

PURPOSE

Posterior capsule opacification (PCO) arises because of a persistent growth of lens epithelial cells. Cultured human lens cells residing on their native collagen capsule and maintained in serum-free medium actively grow and thus show an intrinsic capacity for regulation. In the present study, the authors investigated the role of the putative FGF autocrine system in human capsular bags.

METHODS

Capsular bags were prepared from human donor eyes and maintained in a 5% CO(2) atmosphere at 35 degrees C. On-going observations were by phase-contrast microscopy. Cellular architecture was examined by fluorescence cytochemistry. De novo protein synthesis was determined by the incorporation of 35S-methionine. Basic fibroblast growth factor (FGF) and FGF receptor (R)-1 were detected using enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) techniques. FGFR-1 inhibition was achieved using the specific antagonist SU5402.

RESULTS

Human lens epithelial cells can maintain metabolic activity for more than 1 year in a protein-free medium. Basic FGF was shown to be present in capsular bags throughout culture and also in capsular bags removed from donor eyes that had previously undergone cataract surgery. Furthermore, FGFR-1 was identified. Inhibition of FGFR-1 caused a significant retardation of growth on the posterior capsule. On no occasion did any treated bag reach confluence, whereas all match-paired control samples did.

CONCLUSIONS

The results provide evidence that FGF plays an integral role in the long-term survival and growth of human lens epithelial cells, independent of external stimuli. Inhibition of FGFR-1 by specific synthetic molecules, such as SU5402, could provide a potential therapeutic approach to resolving PCO.

The disposition of gemifloxacin, a new fluoroquinolone antibiotic, in rats and dogs

Gemifloxacin is a fluoroquinolone antibacterial compound with enhanced affinity for bacterial topoisomerase IV and is being developed for the treatment of respiratory and urinary tract infections. The disposition and metabolic fate of this antibiotic was studied in the rat and the dog, the animal species used in its toxicological evaluation. The investigations were carried out following oral and intravenous administration of gemifloxacin mesylate. Gemifloxacin is a racemic compound; therefore, the pharmacokinetics of its individual (+) and (-) enantiomers were characterized using a chiral high-performance liquid chromatography/tandem mass spectrometry assay. In both rat and dog, the pharmacokinetic profiles of the (+) and (-) enantiomers were essentially identical. The enantiomers were rapidly absorbed following oral administration of racemic gemifloxacin mesylate. They distributed rapidly beyond total body water, and their blood clearance values were approximately equal to one quarter of the hepatic blood flow in each species. Terminal phase elimination half-lives were ca. 2 h in the rat and 5 h in the dog. Gemifloxacin was metabolized to a limited extent following oral and intravenous administration of [14C]gemifloxacin mesylate, and all metabolites formed were relatively minor. The principal metabolites formed were the E-isomer (4-6% of dose) and the acyl glucuronide of gemifloxacin (2-6% of dose) in both species and N-acetyl gemifloxacin (2-5% of dose) in the rat. Data obtained following intravenous administration indicated that gemifloxacin-related material is eliminated from the body via urinary excretion, biliary secretion, and gastrointestinal secretion. Material was eliminated approximately equally by the three routes in the dog, whereas a slightly higher proportion of the dose was eliminated in the urine (46%) and a lower proportion in the bile (12%) of rats.

In vitro testing of the bond between soft materials used for maxillofacial prostheses and cast titanium

STATEMENT OF PROBLEM

The choice of soft materials for maxillofacial prostheses is important for covering extraoral defects after tumor surgery or radiation therapy. The use of cast commercially pure titanium as reinforcement seems to be a suitable option.

PURPOSE

Making use of the advantages of titanium frameworks for maxillofacial prostheses requires exploring ways of combining it with soft materials. This study investigated such combinations and evaluated discoloration of the soft material to determine whether it was attributable to the titanium reinforcement.

MATERIAL AND METHODS

Five soft materials used for maxillofacial prostheses and their bond strengths to cast titanium were tested. Different ways of conditioning the titanium surface and different adhesives were used. Plain mechanical retention was also studied. The Gretag SPM 100 was used to determine the potential effects on coloring after 24 hours of radiation in the Suntest rapid exposure unit.

RESULTS

Suitable material combinations for bonding soft materials to titanium were found for all soft materials studied. Bond strength varied depending on the chemical basis of the soft material. Results indicated that maximal bond strengths were obtained by the combinations Supersoft with Super-Bond, Supersoft with subsequent silicoating, and bonding with Dentacolor connector. Few color shifts attributable to the titanium reinforcement were evident in the 2-mm layers of the soft materials applied.

CONCLUSION

The results of this study showed that it is possible to combine a titanium framework and soft silicone materials.

Role of the endoplasmic reticulum in shaping calcium dynamics in human lens cells

PURPOSE

Localized cortical cataracts in the human lens have been shown to involve a selective increase in calcium with no change in sodium content. Recent studies in the rat lens in vitro have shown that the store-operated channel is highly selective for calcium over sodium, and therefore this channel was characterized further in human lens cells.

METHODS

Human primary cultures were initiated from epithelial explants and passaged onto coverslips. After incorporating Fura-2, agonist- or thapsigargin-induced changes in cytosolic calcium were monitored and calibrated using fluorometric digital imaging techniques.

RESULTS

Histamine and adenosine triphosphate (ATP; 10 microM) induced a large transient increase in cytosolic calcium followed by a maintained lower plateau phase in the continued presence of the calcium-signaling agonist. The second phase was abolished by removing external calcium and represented the contribution from the store-operated influx. The store-operated pathway was blocked by inorganic agents such as zinc and nickel (100 microM) but was insensitive to the voltage-sensitive calcium channel blocker, nifedipine (1 mM). Depolarizing the membrane voltage by raising the external potassium (75 mM) also blocked the influx. Similar results were obtained if the store was first emptied directly using thapsigargin (1 microM), and with this agent it was also possible to observe the very slow activation and inactivation kinetics (>10 seconds) of the channel. Addition of manganese to the bathing medium initiated a quench of Fura-2 isobestic fluorescence that was enhanced 2.9 +/- 0.3-fold after 10 microM ATP addition. There was a delay of 82 +/- 16 seconds between initiation of the calcium spike and the Mn2+ quench rate, indicating the presence of a delayed entry pathway. In the resting state, removal of, or increasing extracellular calcium concentration 10-fold did not perturb the level of cytosolic Ca2+. Similar maneuvers performed after agonist- or thapsigargin-induced store depletion of intracellular stores brought about dramatic changes in cytosolic Ca2+ consistent with the activation of a Ca2+ entry pathway. Lower concentrations of agonist induced oscillations of Ca2+ that continued for a short time in Ca-free solution. No increase in Mn2+ quench rate was associated with oscillations. A 100-microM zinc- and KCl-induced blockade of Ca2+ entry had no effect on the form of agonist-induced oscillations. Inhibition of Ca2+ influx by zinc (100 microM) converted a sustained Ca2+ response to a train of repetitive Ca2+ spikes.

CONCLUSIONS

Human lens cells normally have very low Ca2+ permeability. Depletion of intracellular stores by agonists or thapsigargin initiates a Ca2+ entry pathway that is not required for the Ca2+ oscillations induced by low concentrations of agonist. This potentially provides a signal transduction mechanism with minimal risk of Ca2+ overload to the lens, whereas overactivation of the store-operated channel is a possible way of increasing calcium in the lens and could explain the distribution found in localized cataracts.

Sectional neuroanatomy of the upper limb III: forearm and hand

This paper is the last of three articles that describe the functional anatomy of the upper limb. It extends the series by presenting the axial anatomy of the forearm and hand. In addition, it provides a table that defines the patterns of muscle denervation specific to six representative sites. This set of articles is clinically useful because it can be used to rapidly identify and describe the innervation of the muscles and skin of the upper limb.

ICOS is essential for effective T-helper-cell responses

The outcome of T-cell responses after T-cell encounter with specific antigens is modulated by co-stimulatory signals, which are required for both lymphocyte activation and development of adaptive immunity. ICOS, an inducible co-stimulator with homology to CD28, is expressed on activated, but not resting T cells, and shows T-cell co-stimulatory function in vitro. ICOS binds specifically to its counter-receptor B7RP-1 (refs 5,6,7), but not to B7-1 or B7-2. Here we provide in vivo genetic evidence that ICOS delivers a co-stimulatory signal that is essential both for efficient interaction between T and B cells and for normal antibody responses to T-cell-dependent antigens. To determine the physiological function of ICOS, we generated and characterized gene-targeted ICOS-deficient mice. In vivo, a lack of ICOS results in severely deficient T-cell-dependent B-cell responses. Germinal centre formation is impaired and immunoglobulin class switching, including production of allergy-mediating IgE, is defective. ICOS-deficient T cells primed in in vivo and restimulated in vitro with specific antigen produce only low levels of interleukin-4, but remain fully competent to produce interferon-gamma.

Sectional neuroanatomy of the upper limb II: shoulder and upper arm

This article is the second in a series of three that presents an anatomic functional guide to the peripheral innervation of the shoulder and upper limb. It illustrates the axial anatomy of the shoulder and upper arm. The next article continues this format for the lower arm and hand. Together, all three papers can be used to rapidly identify each upper limb muscle and its innervation(s). They can also be used to locate the peripheral nerve trunks, and correlate lesions with the classic pattern(s) of muscle denervation and altered sensation.

Induction of matrix metalloproteinases 2 and 9 following stress to the lens

Matrix metalloproteinase 2 and 9 (MMP-2 and 9, also known as gelatinase A and B) have been implicated in a number of eye diseases, but their possible involvement in lens pathology is yet to be determined. In the present study, we therefore investigated a possible role of matrix metalloproteinases in cataract and posterior capsule opacification. Whole porcine lenses were removed from the eye and cultured in either Eagles Minimum Essential Medium (EMEM) or EMEM supplemented with 1 m M hydrogen peroxide. The medium was sampled and changed every 2 days. On some occasions a sham cataract operation was performed on cultured lenses. The resulting capsular bag was secured to a Petri dish and cultured in EMEM. Culture media from all preparations were analysed for MMP-2 and 9 activity by gelatin zymography. Media samples from lenses which maintained clarity over the 6 day culture period did not display any detectable gelatinolytic activity. However, media from cataractous lenses demonstrated a gelatinolytic band, which had similar molecular weights to the pro-form of MMP-2. In addition to this band, bands with a similar molecular weight to pro-MMP-9 and its dimeric form were also detected in samples obtained from capsular bag preparations within 24 hr. The data presented indicate that normal lenses have undetectable gelatinase activity. However, there is an associated expression of gelatinases with pathological states of the lens, and therefore gelatinase expression could play an important role in cataractogenesis and posterior capsule opacification.

Herpes simplex virus: discovering the link between heparan sulphate and hereditary bone tumours

To gain entry into the host, viruses use host cell surface molecules that normally serve as receptors for other ligands. Herpes simplex virus type 1 (HSV-1) uses heparan sulphate (HS) glycosaminoglycans (GAGs) as receptors for initial attachment to the host cell surface. HS GAGs are both ubiquitous and structurally diverse, and normally serve as critical mediators of interactions between the cell and the extracellular environment. We have used the HS binding ability of HSV-1 to identify the function of a cellular gene, EXT1, which is involved in HS polymerisation. Cellular factors that affect virus growth and replication are often key regulators of the cell cycle and EXT1 is no different-humans with inherited mutations in EXT1 have developmental defects that lead to bone tumours (hereditary multiple exostoses, HME) and sometimes chondrosarcomas. Thus, as a result of using HSV-1 as a molecular probe, a functionally orphaned disease gene now has a defined function. These findings highlight the utility of viruses for investigating important cellular processes.

Distribution of HLA-DQA1, polymarker, CSF1PO, vWA, TH01, TPOX, D16S539, D7S820, D13S317, and D5S818 alleles in East Bengali and West Punjabi populations from Indo-Pak Subcontinent

Blood samples were collected from 115 individuals residing in the Pakistani state of West Punjab and 81 Bengali individuals residing in the state of East Bengal, India. These samples were analyzed for the loci HLA-DQA1, PM (LDLR, GYPA, HBGG, D7S8, and GC) and eight short tandem repeats: CSF1PO, TPOX, THO1, vWA, D16S539, D7S820, D13S317, and D5S818. Departures from Hardy-Weinberg (HWE) were observed in Punjabi population at LDLR, THO1, D13S317, D5S818, and D16S539 and at CSF1PO and THO1 in Bengali population.

A potato alpha-glucosidase gene encodes a glycoprotein-processing alpha-glucosidase II-like activity. Demonstration of enzyme activity and effects of down-regulation in transgenic plants

In order to elucidate more fully the function of a potato gene (MAL1) encoding alpha-glucosidase activity, transgenic plants in which MAL1 expression was down-regulated were generated using antisense technology. In transgenic lines severely down-regulated in the expression of MAL1, total alpha-glucosidase activity was not decreased in leaves and tubers, and the contents of starch, glucose, fructose and sucrose remained unchanged in tubers. Phylogenetic analysis indicated that the MAL1 gene product was more similar to the glycoprotein-processing alpha-glucosidase II of mammalian and yeast origin than to other plant alpha-glucosidases. Using [14C-Glc]-labelled Glc2Man9GlcNAc2 as a substrate, it was demonstrated that glucosidase II activity was markedly down-regulated in microsomes isolated from tubers of four independent antisense lines studied in detail, strongly suggesting that MAL1 encodes glucosidase II activity. In field trials (but not in the glasshouse), MAL1 down-regulation produced an extremely stunted phenotype - the leaves were curled and tuber yield was decreased by 90% compared to control values. Microscopic analysis of leaves revealed significant differences between the antisense and control samples. Plants with down-regulated glucosidase II activity showed a greater degree of plasmolysis, and an increase in the size of mesophyll intracellular spaces. Analysis of cell walls also indicated changes in structure as a result of MAL1 down-regulation. In leaves from four antisense lines, the steady-state transcript level corresponding to the endoplasmic reticulum chaperone, BiP, was enhanced. This is diagnostic of stress in the endoplasmic reticulum.

Characterization of muscarinic receptors in human lens cells by pharmacologic and molecular techniques

PURPOSE

Activation of muscarinic receptors has been implicated in an increased risk of cataract after anticholinesterase treatment for glaucoma. The purpose of the present study was to determine the acetylcholine muscarinic receptor subtype(s) present in native human lens epithelial cells (NHLECs) and a human lens cell line, HLE-B3, and to compare the distribution in other ocular cells.

METHODS

Human lens cells were perfused with artificial aqueous humor (35 degrees C) after fura-2 incorporation, and calcium levels were measured using a fluorometric single-cell digital imaging system. Acetylcholine was the primary muscarinic agonist, and the receptor subtypes were elucidated by determining the relative effectiveness of pirenzepine and AF-DX 384 in blocking the agonist-induced response. The levels of expression of mRNA for the receptor subtypes M1 through M5 were determined by quantitative reverse transcription-polymerase chain reaction (QRT-PCR) using a sequence detection system (ABI Prism 7700; Perkin-Elmer, Foster City, CA). This was performed using total RNA extracted from native lens, retina, iris, and sclera and also cultured lens cells.

RESULTS

Acetylcholine induced a similar concentration-dependent increase in peak-amplitude cytosolic calcium in the range 100 nM to 100 microM in both native and HLE-B3 cells. However, the kinetics of the response waveforms to 30-second pulses of acetylcholine were different in the two cell types. At higher concentrations (> 1 microM), a second phase appeared in the HLE-B3 cells that was absent in the NHLEC response. The 50% inhibitory concentration (IC50) values for blockade of a 1 microM acetylcholine response by pirenzepine and AF-DX 384 were 30 nM and 230 nM, respectively, for NHLECs, and 300 nM and 92 nM, respectively, for HLE-B3 cells. The QRT-PCR data showed that more than 90% of the total muscarinic receptor mRNA from NHLEC was of M1 origin. In the HLE-B3 cells, however, more than 95% of the mRNA was of M3 origin. mRNA for M3 was also in greatest abundance in other eye tissues, although there was a significant contribution from M1 in iris and sclera.

CONCLUSIONS

Both NHLECs and HLE-B3 cells express muscarinic receptors that produce significant changes in cytosolic calcium in response to acetylcholine. Both pharmacologic and QRT-PCR evidence shows that whereas the M1 subtype predominates in NHLECs, M3 is the major contributor in HLE-B3 cells. In all other eye tissues, M3 appears to be the major contributor. These data should be taken into account when choosing particular models to investigate cataract mechanisms and also when designing muscarinic agonists to treat glaucoma.

Mind-body dualism and the biopsychosocial model of pain: what did Descartes really say?

In the last two decades there have been many critics of western biomedicine's poor integration of social and psychological factors in questions of human health. Such critiques frequently begin with a rejection of Descartes' mind-body dualism, viewing this as the decisive philosophical moment, radically separating the two realms in both theory and practice. It is argued here, however, that many such readings of Descartes have been selective and misleading. Contrary to the assumptions of many recent authors, Descartes' dualism does attempt to explain the union of psyche and soma - with more depth than is often appreciated. Pain plays a key role in Cartesian as well as contemporary thinking about the problem of dualism. Theories of the psychological origins of pain symptoms persisted throughout the history of modern medicine and were not necessarily discouraged by Cartesian mental philosophy. Moreover, the recently developed biopsychosocial model of pain may have more in common with Cartesian dualism than it purports to have. This article presents a rereading of Descartes' mental philosophy and his views on pain. The intention is not to defend his theories, but to re-evaluate them and to ask in what respect contemporary theories represent any significant advance in philosophical terms.

PECAM-1 (CD31) expression modulates bleeding time in vivo

PECAM-1 is a 130-kd member of the Ig superfamily present on endothelial cells, platelets, polymorphonuclear leukocytes, monocytes, and lymphocytes. Its expression begins early in development and persists through adulthood. PECAM-1 functions as an adhesion and signaling molecule between adjacent endothelial cells and between endothelial cells and circulating blood elements. Antibodies directed against PECAM-1 have been shown to affect angiogenesis, endothelial cell migration, and polymorphonuclear leukocyte transmigration. Furthermore, its dimerization is associated with the modulation of integrin affinity. Antibody inhibition studies suggest that PECAM-1 plays a role in modulating thrombosis; however, recent in vitro aggregation studies performed on platelets harvested from PECAM-1-deficient mice revealed no abnormalities. In this report we demonstrate prolonged in vivo bleeding times in PECAM-1-deficient mice. This abnormality was not corrected when wild-type hematopoietic precursors were engrafted into marrow-ablated PECAM-1-deficient mice. Furthermore, normal bleeding times were observed when marrow-ablated wild-type mice were engrafted with hematopoietic precursors harvested from PECAM-1-deficient mice. These studies are consistent with a role for PECAM-1 in modulating thrombosis in the vasculature, which is potentially mediated by endothelial cell PECAM-1 expression.

A human lens model of cortical cataract: Ca2+-induced protein loss, vimentin cleavage and opacification

PURPOSE

Cortical cataract in humans is associated with Ca2+ overload and protein loss, and although animal models of cataract have implicated Ca2+-activated proteases in this process, it remains to be determined whether the human lens responds in this manner to conditions of Ca2+ overload. The purpose of these experiments was to investigate Ca2+-induced opacification and proteolysis in the organ-cultured human lens.

METHODS

Donor human lenses were cultured in Eagle's minimum essential medium (EMEM) for up to 14 days. The Ca2+ ionophore ionomycin was used to induce a Ca2+ overload. Lenses were loaded with [3H]-amino acids for 48 hours. After a 24-hour control efflux period, lenses were cultured in control EMEM (Ca2+ 1.8 mM), EMEM + 5 microM ionomycin, or EMEM + 5 microM ionomycin + 5 mM EGTA (Ca2+ < 1 microM). Efflux of proteins and transparency were monitored daily. Protein distribution and cytoskeletal proteolysis were analyzed at the end of the experiment. Cytoskeletal proteins were isolated and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Western blot analyses were probed with anti-vimentin antibody (clone V9) and detected by enhanced chemiluminescence.

RESULTS

Lenses cultured under control conditions remained transparent for 14 days in EMEM with no added supplements or serum. The lenses synthesized proteins and had a low rate of protein efflux throughout the experimental period. Ionomycin treatment resulted in cortical opacification, which was inhibited when external Ca2+ was chelated with EGTA. Exposure to ionomycin also led to an efflux of [3H]-labeled protein, amounting to 41% of the labeled protein over the 7-day experimental period, compared with 12% in ionomycin + EGTA-treated lenses. Efflux was accounted for by loss from the lens soluble protein (crystallin) fraction. Western blot analysis of the cytoskeletal protein vimentin (56 kDa) revealed a distinct breakdown product of 48 kDa in ionomycin-treated lenses that was not present when Ca2+ was chelated with EGTA. In addition, high-molecular-weight proteins (approximately 115 kDa and 235 kDa) that cross-reacted with the vimentin antibody were observed in ionomycin-treated lenses. The Ca2+-induced changes were not age dependent.

CONCLUSIONS

Human lenses can be successfully maintained in vitro, remaining transparent for extended periods. Increased intracellular Ca2+ induces cortical opacification in the human lens. Ca2+-dependent cleavage and cross-linking of vimentin supports possible roles for calpain and transglutaminase in the opacification process. This human lens calcium-induced opacification (HLCO) model enables investigation of the molecular mechanisms of opacification, and the data help to explain the loss of protein observed in human cortical cataractous lenses in vivo.

Safety and pharmacokinetics of a single oral dose of gatifloxacin in patients with moderate to severe hepatic impairment

STUDY OBJECTIVES

To assess the safety and pharmacokinetics of oral gatifloxacin 400 mg in subjects with and without hepatic impairment, and the need to modify doses in patients with hepatic dysfunction.

DESIGN

Single-dose, nonrandomized, open-label, parallel-group study.

SETTING

Clinical Research Center, New Orleans, Louisiana.

PATIENTS

Eight subjects with grade B or C hepatic dysfunction (Child-Pugh classification) and eight age-, weight-, and gender-matched subjects with normal hepatic function.

INTERVENTIONS

After a single oral dose of gatifloxacin 400 mg, blood and urine samples were collected at specified times or intervals over 48 hours to determine drug concentrations.

MEASUREMENTS AND MAIN RESULTS

All 16 subjects (7 with grade B and 1 with grade C hepatic impairment, 8 with normal hepatic function) completed the study. Peak plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC0-infinity) for gatifloxacin were 32% and 22% higher, respectively, in subjects with hepatic impairment. Except for Cmax, the ratio of means for AUC satisfied the specified criterion (0.67-1.50) for lack of effect. There were no statistically significant differences in any other pharmacokinetic values except apparent oral clearance (ClT/F). All treatment-emergent adverse events were mild or moderate in intensity and resolved before subjects were discharged from the study.

CONCLUSION

Modest increases in Cmax and AUC0-infinity are not anticipated to have a negative effect on the outcome of therapy in hepatically impaired subjects, nor are they anticipated to result in adverse drug reactions. Patients with moderate to severe (Child-Pugh grade B or C) hepatic dysfunction do not require gatifloxacin dose adjustments. In addition, the similarity in half-life (t1/2) for the groups (8.9 hrs for hepatically impaired subjects, 9.3 hrs for controls) suggests that no difference would be anticipated in the extent of drug accumulation after multiple doses. The overall safety and tolerability of a single oral dose of gatifloxacin 400 mg were excellent in both healthy subjects and those with hepatic impairment.

Interchangeability of 400-mg intravenous and oral gatifloxacin in healthy adults

STUDY OBJECTIVE

To evaluate the interchangeability of 400-mg intravenous and oral doses of gatifloxacin.

DESIGN

Randomized, open-label, crossover study.

SETTING

GFI Pharmaceutical Services, Inc., Evansville, Indiana, USA.

SUBJECTS

Twenty-four healthy men and women (12 of each gender), aged 18-42 years.

INTERVENTIONS

Subjects received single doses of gatifloxacin 400 mg either by intravenous infusion over 1 hour or a 400-mg tablet orally with 240 ml of water, each dose separated by a 1-week washout. Plasma concentrations of gatifloxacin were determined by a validated high-performance liquid chromatography; pharmacokinetic parameters were calculated using noncompartmental methods. Distributions of pharmacokinetic parameter values were summarized by route of administration and gender. Effects of treatment on pharmacokinetic parameter values of gatifloxacin were assessed by an analysis of variance model suitable for a two-way, two-treatment, crossover design. Clinical evaluations were performed to assess drug safety and tolerability.

MEASUREMENTS AND MAIN RESULTS

Intravenous and oral gatifloxacin were considered interchangeable because both routes were bioequivalent with respect to area under the curve (AUC; 90% confidence interval for the ratio of geometric means contained within 0.8-1.25). The plasma concentration-time profile after intravenous administration was similar and comparable in extent of exposure (AUC0-infinity) with that for the oral route when equal doses were administered to men and women. The absolute bioavailability of gatifloxacin after oral administration was 96%, consistent with bioequivalence of the 400-mg intravenous and oral doses. The drug was well tolerated; the frequency of adverse events was comparable after intravenous and oral administration.

CONCLUSION

Intravenous and tablet formulations of gatifloxacin are bioequivalent and therefore interchangeable. This permits greater flexibility in choosing oral or parenteral therapy, with the possibility of avoiding hospitalization based on knowledge that oral administration will deliver therapeutic exposure to the drug, or abbreviating hospital stay due to ease of switching from intravenous to oral therapy.

A dose-escalation study of the safety, tolerability, and pharmacokinetics of intravenous gatifloxacin in healthy adult men

STUDY OBJECTIVES

To examine single- and multiple-dose safety, tolerability, and pharmacokinetics of gatifloxacin administered as daily 1-hour intravenous infusions for 14 days, and to determine the effect of gatifloxacin on glucose tolerance, pancreatic beta-cell function, and electrocardiogram (ECG).

DESIGN

Randomized, double-blind, placebo-controlled, ascending-dose study.

SETTING

Bristol-Myers Squibb, Clinical Pharmacology Unit, Princeton, New Jersey, USA.

PATIENTS

Forty healthy male subjects, eight in each of five groups, were enrolled to receive sequential doses of gatifloxacin: 200 mg (10 mg/ml), 200 mg (1 mg/ml), and 400, 600, and 800 mg (2 mg/ml); six subjects per group received active drug and two received placebo.

INTERVENTIONS

A single dose of the drug was administered as an intravenous infusion over 1 hour. After a 72-hour washout period, the drug was administered once/day for 14 days by 1-hour intravenous infusion. Physical examinations, ECGs, spirometry, and clinical laboratory tests, including glucose tolerance test (GTT) and assessment of glucose homeostasis, were performed before treatment and on selected dosing days. A safety evaluation was performed before escalating doses. No intrasubject dose escalation was permitted.

MEASUREMENTS AND MAIN RESULTS

The pharmacokinetics of gatifloxacin were dose linear and time independent after intravenous administration over the range of 200-800 mg. After daily repeated administration, a predictable, modest accumulation was observed; steady state was reached by the third dose. Approximately 80% of the dose was recovered as unchanged drug in urine. Mean changes (before the first dose to the last dose) after oral GTT and in fasting serum glucose, insulin, and C-peptide concentrations were comparable among the gatifloxacin and placebo treatment groups. A mild, transient decrease in serum glucose was associated with the end of the 1-hour infusion of gatifloxacin. No clinically important changes in QTc interval or spirometry occurred. The most frequent treatment-related adverse effects were local intravenous site reactions, which were associated with dose and/or concentration of intravenous solution.

CONCLUSION

Gatifloxacin was safe and well tolerated at intravenous doses of up to 800 mg/day for 14 days. Gatifloxacin pharmacokinetics were linear and time independent.

Age and gender effects on the pharmacokinetics of gatifloxacin

STUDY OBJECTIVE

To compare the pharmacokinetics and safety of gatifloxacin in elderly (> or = 65 yrs) and young (18-45 yrs) men and women.

DESIGN

Open-label, parallel-group, single-dose study.

SETTING

GFI Pharmaceutical Services Inc., Evansville, Indiana, USA.

SUBJECTS

Forty-eight healthy subjects in four groups of 12 each.

INTERVENTIONS

Subjects received single oral doses of gatifloxacin 400 mg. Serial blood and urine samples were collected for 96 hours after dosing to determine drug concentrations.

MEASUREMENTS AND MAIN RESULTS

Age and gender had moderate effects on the pharmacokinetics of gatifloxacin. Elderly women had a 21% higher geometric mean peak plasma concentration (Cmax) and a 32% higher area under the plasma concentration-time curve (AUC0-infinity) than young women. Adjustment for creatinine clearance had only a slight effect on Cmax but reduced the estimated effect of age on AUC0-infinity in women from a 32% increase to a 15% increase. Gender effects on pharmacokinetic values were noted among elderly subjects only. Geometric means for Cmax and AUC0-infinity were 21% and 33% higher, respectively, for elderly women and elderly men. Adjustment for body weight reduced these differences to 11% and 20%, respectively.

CONCLUSION

The effects of age on gatifloxacin pharmacokinetic values were largely attributed to declining renal function, whereas those of gender were largely attributed to differences in body weight. These modest age- and gender-related differences do not warrant dosage adjustment.

Lens cell populations studied in human donor capsular bags with implanted intraocular lenses

PURPOSE

Posterior capsule opacification is an ongoing cellular redistribution process. The level of viable cell coverage was therefore determined in human donor capsular bags with implanted intraocular lenses, and cellular morphology and ultrastructure were investigated in relation to cell type and level of differentiation.

METHODS

Donor capsular bags, retrieved at intervals of 4 months to 13 years after surgery, were investigated by phase optics before fixation. Postfixation techniques included scanning electron microscopy and transmission electron microscopy of sections and immunofluorescent staining of cytoskeletal proteins in wholemounts.

RESULTS

All the capsular bags contained a large population of viable cells on the capsular surfaces. Cells on the anterior face of the anterior capsule and in the spaces around the intraocular lens had an elongated morphology and expressed alpha-smooth muscle actin. The cells formed light-scattering, multilayered aggregates and strands that were surrounded by layers of extracellular matrix. The regions between the intraocular lens and the equator of the bags were populated by monolayers of epithelial cells of normal morphology and ultrastructure, on both the anterior and posterior capsules. In some regions the apical surfaces of the two epithelial monolayers were in contact, and in some parts of the equatorial regions, differentiation of cells into well-organized fiberlike cells was evident.

CONCLUSIONS

Human capsular bags contain a large population of viable cells for many years after cataract surgery. Cells in the regions around the intraocular lens undergo transition to a mesenchymal type. Cells peripheral to these regions can form a stable closed microenvironment in which both normal epithelial morphology and differentiation to fiberlike cells are maintained.