Effects of soma isolation on outward currents measured under voltage clamp in spiny lobster stomatogastric motor neurons.

1. Outward currents in identified cell types from the pyloric system of the stomatogastric ganglion (STG) of the spiny lobster, Panulirus marginatus, were studied under two-microelectrode voltage clamp. A comparison was made between data from intact cells and somata isolated by ligation of the primary neurite of these monopolar neurons. 2. Despite the elimination of current contributions from the extensive arborizations of STG neurons, few significant differences were found in the mean values of parameters for outward currents between populations of isolated somata and intact cells of a given type. Measurements that showed little difference included magnitude and activation threshold of a calcium-dependent outward current (IJ) and magnitude, activation threshold, voltage dependence, and inactivation time course of A current (IA). Although previous work has suggested that IJ might reside predominantly in the soma, IA is known to be distributed in poorly space-clamped neurite processes. The absence of obvious effects of isolation was thus unexpected. 3. To better understand the mechanisms involved, we used compartmental models derived from reconstructed neurons to simulate the effects of isolation. It was concluded that, for the particular conditions present in stomatogastric neurons, with a large, uniformly distributed outward current conductance activated, even though neurites and axon remain attached, most measured current flows through well-clamped soma membrane. 4. Factors contributing to this result included the outward sign of the current, the large specific conductance activated in these neurons (among the larger reported in somata), and the presence of only a single major process leaving the soma. The potential for serious errors in voltage-clamp measurements from intact cells remains if these conditions are not met.

Primary idiopathic hypoparathyroidism in St. Bernard dogs.

Primary hypoparathyroidism was diagnosed in three St. Bernard bitches. Anorexia, behavioural changes, muscle tremors, seizures, panting respiration, and cataracts were the clinical signs observed. The serum concentration of calcium was low, the phosphorus concentration elevated, and the immunoreactive parathyroid hormone level low in all dogs. The aetiology of the hypoparathyroidism was not determined in any of the dogs. Treatment with synthetic vitamin D (1,25-dihydroxycholecalciferol) and an oral calcium supplement was successful in restoring and then maintaining a normal concentration of serum calcium in two of the dogs.

Antiviral activity in the rabbit cornea of adenine arabinoside, Ara-A 5' monophosphate, and hypoxanthine arabinoside; and interactions with adenosine deaminase inhibitor.

The multiple microtrephination technique was used in the rabbit cornea to compare the activity against herpes simplex virus (hsv) of adenine arabinoside (ara-A), ara-A 5'monophosphate (ara-AMP) and hypoxanthine arabinoside (ara-Hx), and to determine the effect of addition of adenosine deaminase inhibitor (ADAI) to each. The greatest antiviral activity was shown by ara-AMP, and the least by ara-Hx. ADAI increased the activity of ara-A but had no effect on ara-AMP or ara-Hx.

Treatment of TRIC infection of the eye with rifampicin or chloramphenicol.

An open trial was carried out on 63 patients in London to assess the efficacy of 1% rifampicin eye ointment in comparison with 1% chloramphenicol eye ointment in the treatment of sexually transmitted TRIC infection of the eye. Patients included were selected on the basis of positive cultures for Chlamydia trachomatis. Three weeks' treatment with rifampicin eye ointment used 3 times daily was not sufficient to cure the disease, but a 6 or 7 week course gave 90% clinical and microbiological cure rate. Treatment with chloramphenicol eye ointment 3 times daily for 4 to 6 weeks failed to cure the disease.

Proflavine photodynamic viral inactivation in herpes simplex keratitis.

We used the photodynamic inactivation technique with proflavine as the photoactive dye to treat herpetic epithelial keratitis in a preliminary study of patients who had idoxuridine toxicity or resistance. A comparative study with idoxuridine in treating dendritic ulcerations of the cornea showed a good therapeutic effect. But the investigation was suspended when adverse reactions, consisting of a generalized epithelial keratitis and an anterior uveitis, possibly of phototoxic origin, developed in a few patients receiving treatment. The ulcers treated by photodynamic inactivation apparently healed by a process of "debridement" followed by subsequent re-epithelialization.

Principles in the management of oculomycosis. XXXI Edward Jackson memorial lecture.

Effective antifungal therapy must be long-term, nondamaging, penetrating to the eye, and highly active against each patient's fungus. Results of antifungal sensitivity testing of 61 collected ocular fungal pathogens and observations in 25 cases treated with one of the nonpolyene antifungal drugs indicated that infection was rapidly controlled and eradicated with restoration of visual acuity, determined by the degree of disorganization present at the time of commencement of rational specific antifungal therapy. Pimaricin has the widest spectrum, a medium level of activity, and rather poor penetration but is recommended as an antifungal prophylactic and as first-line-therapy for ocular fungal disease while awaiting identification and sensitivity testing of the fungus. Flucytosine combined with amphotericin B, or possibly with clotrimazole or miconazole, is recommended for Candida infections. Clotrimazole is the drug of choice for Aspergillus species although miconazole and econazole are more effective with some isolates. Miconazole and econazole are recommended for miscellaneous filamentous fungi although clotrimazole or thiabendazole are superior in some cases. Each of these drugs may be useful in patients infected with Fusarium who do not respond to primaricin. In these cases, drug use should be guided by the results of antifungal sensitivity testing. In addition to medical antifungal therapy some eyes may require excisional keratoplasty with the lens removal and evacuation of the posterior chamber and anterior vitreous cavity.