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Biomedical subjects

C M Rogers

Publications and source records attributed to C M Rogers.

At least 19 recordsLinked to original sources
PubMed2001

Regulation of the pharynx of Caenorhabditis elegans by 5-HT, octopamine, and FMRFamide-like neuropeptides.

More than fifty FMRFamide-like neuropeptides have been identified in nematodes. We addressed the role of a subset of these in the control of nematode feeding by electrophysiological recording of the activity of C. elegans pharynx. AF1 (KNEFIRFamide), AF2 (KHEYLRFamide), AF8 (KSAYMRFamide), and GAKFIRFamide (encoded by the C. elegans genes flp-8, flp-14, flp-6, and flp-5, respectively) increased pharyngeal action potential frequency, in a manner similar to 5-HT. In contrast, SDPNFLRFamide, SADPNFLRFamide, SAEPFGTMRFamide, KPSVRFamide, APEASPFIRFamide, and AQTVRFamide (encoded by the C. elegans genes flp-1; flp-1; flp-3; flp-9; flp-13, and flp-16, respectively) inhibited the pharynx in a manner similar to octopamine. Only three of the neuropeptides had potent effects at low nanomolar concentrations, consistent with a physiological role in pharyngeal regulation. Therefore, we assessed whether these three peptides mediated their actions either directly on the pharynx or indirectly via the neural circuit controlling its activity by comparing actions between wild-type and mutants with deficits in synaptic signaling. Our data support the conclusion that AF1 and SAEPFGTMRFamide regulate the activity of the pharynx indirectly, whereas APEASPFIRFamide exerts its action directly. These results are in agreement with the expression pattern for the genes encoding the neuropeptides (Kim and Li, 1999) as both flp-8 and flp-3 are expressed in extrapharyngeal neurons, whereas flp-13 is expressed in I5, a neuron with synaptic output to the pharyngeal muscle. These results provide the first, direct, functional information on the action of neuropeptides in C. elegans. Furthermore, we provide evidence for a putative inhibitory peptidergic synapse, which is likely to have a role in the control of feeding.

Animals↗
PubMed2001

Epithelial ingrowth: causes, prevention, and treatment in 5 cases.

PURPOSE: To examine the clinical course, treatment, and outcome in 5 cases of epithelial ingrowth following laser in situ keratomileusis (LASIK). SETTING: The Eye Institute, Sydney, Australia. METHODS: Five patients with adequate follow-up were selected. Each patient had developed epithelial ingrowth as a consequence of LASIK, and each represented a different clinical course in terms of severity, time, and treatment of the epithelial ingrowth. RESULTS: Treatment ranged from observation, lifting and manual removal, phototherapeutic keratectomy, alcohol application, removal of the corneal cap, and penetrating keratoplasty (PKP). Outcomes ranging from retention of preoperative best corrected visual acuity to the need for PKP reflect the wide disparity in the severity of this complication and the therapeutic interventions required. CONCLUSION: Epithelial ingrowth is a relatively uncommon complication following LASIK. Suggestions for prevention and treatment are made.

Adult↗
PubMed2001

Successful treatment of Paecilomyces lilacinus endophthalmitis after foreign body trauma to the cornea.

PURPOSE: To report the successful treatment of a patient with Paecilomyces lilacinus endophthalmitis infection after foreign body (FB) trauma to the cornea. METHODS: A 30-year-old man presented to us with a corneal abscess and iritis 2 months after removal of a metal corneal FB. Initial corneal biopsy culture was negative. Treatment with topical 5% natamycin, 0.9% fortified gentamycin, and 5% cephalothin hourly was commenced. As a result of developing signs of endophthalmitis, two more biopsies were taken, a week apart, from the vitreous and anterior chamber, successively. The last biopsy yielded positive microbiologic results of the specious Paecilomyces lilacinus. Intravitreal injection of 50 microg/0.5 mL of amphotericin was administered during the vitreal biopsy. Soon after isolating the specious Paecilomyces lilacinus, the following treatment was administered: 200 mg of itraconazole bd by mouth, 5% topical natamycin every hour, 2 mg/mL of topical fluconazole every 2 hours, three anterior chamber injections of 0.35 mL of 0.1% fluconazole and two amphotericin B injections to the anterior chamber of 50 microg/0.5 mL each. RESULTS: There appeared to be no sign of infection 6 months after initial treatment. A large, dense scar existed in the medial part of the cornea only. The pupil was secluded. The patient's visual acuity was 6/21. The eye was comfortable and all topical antifungal medication was ceased.

Adult↗
PubMed2001

Corneal deposition after high-dose chlorpromazine hydrochloride therapy.

PURPOSE: To report a case of dermal and ocular changes after prolonged use of high-dose chlorpromazine hydrochloride therapy. METHOD: This case report includes clinical history, clinical findings, and photographic images of ocular and dermal changes. RESULTS. Chlorpromazine therapy in a cumulative dosage exceeding 1,100 g resulted in dramatic skin discoloration and multiple crystalline deposits in both corneas. Anterior capsular opacities were binocularly present. These changes were sufficient to cause reduction in visual acuity. CONCLUSIONS: Chlorpromazine deposition at high levels can cause reduction in visual acuity and significant skin discoloration.

Antipsychotic Agents↗
PubMed2001

Differential sensitivity to calciseptine of L-type Ca(2+) currents in a 'lower' vertebrate (Scyliorhinus canicula), a protochordate (Branchiostoma lanceolatum) and an invertebrate (Alloteuthis subulata).

Voltage-dependent calcium currents in vertebrate (Scyliorhinus canicula), protochordate (Branchiostoma lanceolatum), and invertebrate (Alloteuthis subulata) skeletal and striated muscle were examined under whole-cell voltage clamp. Nifedipine (10 microM) suppressed and cobalt (5 mM) blocked striated/skeletal muscle calcium currents in all of the animals examined, confirming that they are of the L-type class. Calciseptine, a specific blocker of vertebrate cardiac muscle and neuronal L-type calcium currents, was applied (0.2 microM) under whole-cell voltage clamp. Protochordate and invertebrate striated muscle L-type calcium currents were suppressed while up to 4 microM calciseptine had no effect on dogfish skeletal muscle L-type calcium currents. Our results demonstrate the presence of at least two sub-types of L-type calcium current in these different animals, which may be distinguished by their calciseptine sensitivity. We conclude that the invertebrate and protochordate L-type current sub-type that we have examined has properties in common with vertebrate 'cardiac' and 'neuronal' current sub-types, but not the skeletal muscle sub-type of the L-type channel.

Animals↗
PubMed1999

Ring keratitis from topical anaesthetic misuse.

BACKGROUND: Topical anaesthetic abuse is now an established differential diagnosis of ring keratitis. Published evidence suggests that this condition often has a poor prognosis, with the eyes sometimes requiring penetrating keratoplasty or the patient becoming blind. METHOD: A case of topical anaesthetic abuse and its subsequent management is presented. Ocular examination including pachymetry and specular microscopy is reported. RESULTS: The cornea made an excellent recovery, allowing a visual acuity of 6/6. Pachymetry showed corneal thickening and specular microscopy demonstrated a decreased cell count in the affected eye. CONCLUSIONS: With prompt recognition and appropriate treatment the prognosis for these cases can be excellent. However, there is evidence to suggest permanent cellular damage to the endothelium.

Adult↗
PubMed1999

Staphylococcal infection under a LASIK flap.

PURPOSE: To report a staphylococcal infection under a laser in situ keratomileusis (LASIK) flap and to discuss the management of this rare and potentially devastating complication. METHODS: A patient was referred to our practice having had bilateral LASIK. She was found to have abscesses under the left corneal flap. Staphylococcus aureus was identified as the infecting organism by corneal scrape and treated with appropriate antibiotics. The cornea improved, and then the abscess recurred. The abscess was again scraped and intensive treatment reinstituted. RESULTS: After successful treatment, the patient recovered excellent visual acuity with only a minimal astigmatic error. CONCLUSION: The possible reasons for the apparent improvement and then recurrence of the abscess are discussed. The management of this case including the need for corneal scrape and antibiotic prophylaxis is discussed in relation to previously reported cases.

Abscess↗
PubMed1999

LASIK for post penetrating keratoplasty astigmatism and myopia.

AIMS: To report the results of a series of patients who were treated with LASIK to correct post penetrating keratoplasty ametropia. METHODS: 26 eyes of 24 patients underwent LASIK to correct astigmatism and myopia after corneal transplantation; 14 eyes also received arcuate cuts in the stromal bed at the time of surgery. The mean preoperative spherical equivalent was -5.20D and the mean preoperative astigmatism was 8.67D. RESULTS: The results of 25 eyes are reported. The mean 1 month values for spherical equivalent and astigmatism were -0.24D and 2.48D respectively. 18 eyes have been followed up for 6 months or more. The final follow up results for these eyes are -1.91D and 2.92D for spherical equivalent and astigmatism. The patients undergoing arcuate cuts were less myopic but had greater astigmatism than those not. The patients receiving arcuate cuts had a greater target induced astigmatism, surgically induced astigmatism, and astigmatism correction index than those eyes that did not. One eye suffered a surgical complication. No eyes lost more than one line of BSCVA and all eyes gained between 0 and 6 lines UCVA. CONCLUSIONS: LASIK after penetrating keratoplasty is a relatively safe and effective procedure. It reduces both the spherical error and the cylindrical component of the ametropia. Correction of high astigmatism may be augmented by performing arcuate cuts in the stromal bed.

Adult↗
PubMed1998

NCQA and HEDIS.

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Accreditation↗
PubMed1997

Different excitation-contraction coupling mechanisms exist in squid, cuttlefish and octopod mantle muscle

Excitation-contraction (EC) coupling was studied in central zone mantle muscle fibres of a squid (Alloteuthis subulata), a cuttlefish (Sepia officinalis) and an octopod (Eledone cirrhosa). Thin slices of muscle were used for twitch experiments and enzymatic isolation of single fibres for whole-cell patch-clamp studies. The current required for a supramaximal twitch response during direct stimulation of muscle slices was lower for squid than for cuttlefish. In squid, but not in cuttlefish, the current-response relationship was independent of slice thickness (range 0.1-0.5 mm). Twitches of squid and cuttlefish slices were reversibly abolished by removal of extracellular Ca2+. In squid, but not in cuttlefish, the current-response relationship was Na+-dependent, and in the absence of Na+ higher current strengths were required to generate a supramaximal response. In whole-cell voltage-clamp experiments on isolated muscle fibres from squid, cuttlefish and Eledone cirrhosa, a sustained inward current was recorded upon depolarisation. This current was blocked by 5 mmol l-1 Co2+ and suppressed by 10 micromol l-1 nifedipine. In squid, an additional inward fast-activating transient current was seen which was blocked by 2 micromol l-1 tetrodotoxin and depolarised holding potentials. The fast current represents a voltage-activated Na+ channel, and the slow currents represent L-type Ca2+ channels. We conclude that squid possess a specialised rapid EC coupling mechanism in central zone fibres that is absent in cuttlefish and Eledone cirrhosa.

Journal Article↗
PubMed1995

Cornea plana.

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Cataract Extraction↗
PubMed1992

Localisation of the mitogenic epitope of staphylococcal enterotoxin B.

Limited digestion of staphylococcal enterotoxin B (SEB) with trypsin resulted in the generation of a 12-Kda amino-terminal fragment and a 17-Kda carboxy-terminal fragment which were isolated by preparative iso-electric focusing. The carboxy-terminal fragment exhibited significant mitogenic activity for murine splenocytes, whereas the isolated amino-terminal fragment possessed little detectable mitogenic activity. Monoclonal antibodies (MAbs) specific for the carboxy-terminal fragment neutralised most of the mitogenic activity of both the intact toxin and the carboxy-terminal fragment. MAbs specific for the amino-terminal fragment had no detectable neutralising activity. These results support the hypothesis that the epitope(s) responsible for mitogenic activity is located in the carboxy-terminal region of SEB.

Amino Acid Sequence↗
PubMed1989

Calmodulin is associated with microtubules forming in PTK1 cells upon release from nocodazole treatment.

To investigate the association of calmodulin (CaM) with microtubules (MTs) in the mitotic apparatus (MA), the distributions of CaM and tubulin were examined in cells in which the normal spindle organization had been altered. A fluorescent CaM conjugate with tetramethylrhodamine isothiocyanate (CaM-TRITC) and a dichlorotriazinyl aminofluorescein conjugate with tubulin (tubulin-DTAF) were injected into cells that had been treated with the MT inhibitor nocodazole. With moderate nocodazole concentration (0.3 micrograms/ml, 37 degrees C, 4 h) in live cells, CaM-TRITC and tubulin-DTAF concentrated identically on or near the centrosomes and kinetochores. In serial sections of these cells, small MT segments were observed by transmission electron microscopy (TEM) in the regions where fluorescent protein had concentrated. When a higher drug concentration was used (3.0 micrograms/ml, 37 degrees C, 4 h), no regions of CaM-TRITC or tubulin-DTAF localization were observed, and no MTs were observed when serial sections were examined by TEM. However, following release from the high-concentration nocodazole block, CaM-TRITC colocalized with newly formed MTs at the kinetochores and centrosomes. Later in the recovery period, when chromosome-to-pole fibers had formed, CaM association with kinetochores diminished, ultimately attaining its normal pole-proximal association with kinetochore MTs in cells that progressed through mitosis. We interpret these observations as supporting the hypothesis that in the MA, CaM attains a physical association with kinetochore MTs and suggest that CaM-associated MTs may be inherently more stable.

Animals↗
PubMed1988

Calmodulin stabilization of kinetochore microtubule structure to the effect of nocodazole.

To investigate the function of calmodulin (CaM) in the mitotic apparatus, the effect of microinjected CaM and chemically modified CaMs on nocodazole-induced depolymerization of spindle microtubules was examined. When metaphase PtK1 cells were microinjected with CaM or a CaM-TRITC conjugate, kinetochore microtubules (kMTs) were protected from the effect of nocodazole. The ability of microinjected CaM to subsequently protect kMTs from the depolymerizing effect of nocodazole was dose dependent, and was effective for approximately 45 min, with protection decreasing if nocodazole treatment was delayed for more than 60 min after injection of CaM. The CaM-TRITC conjugate, similar to native CaM, displayed the ability to activate bovine brain CaM-dependent adenylate cyclase in a Ca++-dependent manner and showed a Ca++-dependent mobility shift when subjected to PAGE. A heat-altered CaM-TRITC conjugate also protected kMTs from the effect of nocodazole. However, this modified CaM was not able to activate adenylate cyclase nor did it display a Ca++-dependent mobility shift when electrophoresed. In a permeabilized cell model system, both CaM analogs were observed to bind to the spindle in a Ca++-independent manner. In contrast, a performic acid-oxidized CaM did not have a protective effect on spindle structure when microinjected into metaphase cells before nocodazole treatment. The oxidized CaM did not activate adenylate cyclase and did not exhibit Ca++-dependent mobility on polyacrylamide gels. These results are interpreted as supporting the hypothesis that CaM binds to the mitotic spindle in a Ca++-independent manner and that CaM may serve in the spindle, at least in part, to stabilize kMTs.

Animals↗