Congenital hyposomatotropism in a domestic shorthair cat presenting with congenital corneal oedema.

A six-month-old, female, domestic shorthair cat was presented with a history of failure to grow and bilateral corneal opacity caused by corneal oedema. Congenital hyposomatotropism and possible secondary hypothyroidism were diagnosed on the basis of fasting serum levels of insulin-like growth factor-1 and thyroxine levels, respectively. These endocrinopathies are rare in the cat and have not been reported to cause ocular signs. The cat died during investigation of these diseases, and histopathological examination of the eyes showed significantly reduced corneal endothelial cell density and number of corneal epithelial cell layers when compared with age-matched healthy control corneas. These changes were implicated in the development of the corneal oedema.

An immunohistochemical investigation of canine idiopathic granulomatous scleritis.

The clinical, histopathologic and immunohistochemical findings in three dogs with granulomatous scleritis are reported. The lesions of granulomatous scleritis were characterized by vasculitis, collagenolysis, granulomatous inflammation and perivascular lymphoplasmacytic aggregation. There was evidence of vascular immune complex deposition, and the inflammatory aggregates contained T lymphocytes, IgG plasma cells and macrophages expressing class II molecules of the major histocompatibility complex (MHC). There was no evidence for an infectious etiology in any case, and one of the dogs subsequently developed cutaneous vascular disease consistent with a systemic immune-mediated disorder. Canine granulomatous scleritis has an immunopathogenesis likely involving primary type IV hypersensitivity, with a probable underlying type III involvement.

Canine keratoconjunctivitis sicca: disease trends in a review of 229 cases.

OBJECTIVES: To investigate the disease patterns in dogs with keratoconjunctivitis sicca referred to the University of Glasgow Small Animal Hospital. METHODS: A retrospective study of 229 cases was carried out. RESULTS: There were 44 breeds in the study, with four breeds, English cocker spaniels, cavalier King Charles spaniels, West Highland white terriers and shih-tzus, making up 58 per cent of the cases. Among these four breeds, two breed-dependent disease patterns, one chronic and one acute, were identified. English cocker spaniels and West Highland white terriers had a mean age at onset of clinical signs of five years and one month and five years and six months, respectively, with more females affected than males. Clinical signs consisted predominantly of conjunctival hyperaemia and mucopurulent discharge, with a relatively low incidence of ulcerative keratitis. In contrast, cavalier King Charles spaniels and shih-tzus showed a more acute disease pattern with a biphasic age distribution at 0 to less than two years of age, and four to less than six and six to less than eight years of age, respectively, with more males affected than females and a significantly higher incidence of ulcerative keratitis in some cases resulting in corneal perforation. CLINICAL SIGNIFICANCE: The study reveals interbreed differences with respect to sex, age and risk of ulcerative keratitis which have not been detailed previously in a referral population.

muO-conotoxin MrVIB selectively blocks Nav1.8 sensory neuron specific sodium channels and chronic pain behavior without motor deficits.

The tetrodotoxin-resistant voltage-gated sodium channel (VGSC) Na(v)1.8 is expressed predominantly by damage-sensing primary afferent nerves and is important for the development and maintenance of persistent pain states. Here we demonstrate that muO-conotoxin MrVIB from Conus marmoreus displays substantial selectivity for Na(v)1.8 and inhibits pain behavior in models of persistent pain. In rat sensory neurons, submicromolar concentrations of MrVIB blocked tetrodotoxin-resistant current characteristic of Na(v)1.8 but not Na(v)1.9 or tetrodotoxin-sensitive VGSC currents. MrVIB blocked human Na(v)1.8 expressed in Xenopus oocytes with selectivity at least 10-fold greater than other VGSCs. In neuropathic and chronic inflammatory pain models, allodynia and hyperalgesia were both reduced by intrathecal infusion of MrVIB (0.03-3 nmol), whereas motor side effects occurred only at 30-fold higher doses. In contrast, the nonselective VGSC blocker lignocaine displayed no selectivity for allodynia and hyperalgesia versus motor side effects. The actions of MrVIB reveal that VGSC antagonists displaying selectivity toward Na(v)1.8 can alleviate chronic pain behavior with a greater therapeutic index than nonselective antagonists.

Effects of medetomidine and medetomidine-butorphanol combination on Schirmer tear test 1 readings in dogs.

Medetomidine is a commonly used sedative in veterinary medicine whether administered alone or in combination with an opioid such as butorphanol. There are no previous studies that look at the effects of this drug on sequential Schirmer tear test (STT) 1 readings in dogs, including effects on tear production after reversal of the drug. The present study looked at two groups of 10 dogs each that were sedated with intravenous medetomidine or a combination of medetomidine and butorphanol. All dogs had tear readings taken presedation, 15 min postsedation, and 15 min after reversal of medetomidine with atipamezole. Results revealed that intravenous sedation with medetomidine and medetomidine-butorphanol in dogs with no history of ophthalmic disease and presedation STT 1 readings above 15 mm/min, causes a significant decrease in tear production that is measurable at 15 min postsedation. Readings returned to near presedation values within 15 min postreversal in most cases. It is therefore recommended that all eyes be treated with a tear substitute from the time the sedative is given until at least 15 min after reversal.

Systemic hypertensive disease and the feline fundus.

The fundoscopic appearance and some of the histopathological findings of arterial hypertension in the cat are reviewed in relation to the anatomical and physiological features that place retinal function at particular risk when the eye is subjected to sustained increased arterial blood pressure. The fundus changes fall into three categories: hypertensive retinopathy, hypertensive choroidopathy and hypertensive optic neuropathy, and information from cases with confirmed arterial hypertensive disease is used to provide a basis for discussion and future investigation.

Permeation and activation of the M2 ion channel of influenza A virus.

The M(2) ion channel protein of influenza A virus is essential for mediating protein-protein dissociation during the virus uncoating process that occurs when the virus is in the acidic environment of the lumen of the secondary endosome. The difficulty of determining the ion selectivity of this minimalistic ion channel is due in part to the fact that the channel activity is so great that it causes local acidification in the expressing cells and a consequent alteration of reversal voltage, V(rev). We have confirmed the high proton selectivity of the channel (1.5-2.0 x 10(6)) in both oocytes and mammalian cells by using four methods as follows: 1) comparison of V(rev) with proton equilibrium potential; 2) measurement of pH(in) and V(rev) while Na(+)(out) was replaced; 3) measurements with limiting external buffer concentration to limit proton currents specifically; and 4) comparison of measurements of M(2)-expressing cells with cells exposed to a protonophore. Increased currents at low pH(out) are due to true activation and not merely increased [H(+)](out) because increased pH(out) stops the outward current of acidified cells. Although the proton conductance is the biologically relevant conductance in an influenza virus-infected cell, experiments employing methods 1-3 show that the channel is also capable of conducting NH(4)(+), probably by a different mechanism from H(+).

Cadmium withdrawal contractures in rat soleus muscle fibres.

Transient "Cd2+ withdrawal" contractures, with amplitudes of < or =60% peak tetanic tension, were seen when > or =3 mM Cd2+ was removed, after exposures lasting > or =5 min, from solutions bathing rat soleus fibres at 22 degrees C with Cl- as the major external anion. The minimum free [Cd2+] for withdrawal contractures was reduced twofold when the external anion was SO4(2-). Withdrawal contractures were not seen after removal of 3 mM Co2+, Zn2+ or La3+ and were not observed in rat extensor digitorum longus fibres. The contractures were not due to depolarization (membrane potential, Vm, did not change during Cd2+ removal) or to an influx of external Ca2+ (the transient tension increase was recorded when solutions either lacked Ca2+, or contained 2 mM Co2+). Cd2+ withdrawal contractures were abolished by inactivation of excitation-contraction coupling (ECC) following depolarization in 40 mM K+ for 20 min, and recovered from inactivation at the same time as twitch and tetanic contractions with repriming of ECC. Withdrawal contractures were depressed by agents that depress ECC, i.e. low [Ca2+], 2 mM Co2+, 30 mM Ca2+, 30 mM Mg2+ and 50 microM nifedipine. The results support a hypothesis in which withdrawing Cd2+ from the external solution induces a contracture by activating the voltage sensor for ECC.

Mechanism for proton conduction of the M(2) ion channel of influenza A virus.

The M(2) integral membrane protein of influenza A virus forms a proton-selective ion channel. We investigated the mechanism for proton transport of the M(2) protein in Xenopus oocytes using a two-electrode voltage clamp and in CV-1 cells using the whole cell patch clamp technique. Membrane currents were recorded while manipulating the external solution to alter either the total or free proton concentration or the solvent itself. Membrane conductance decreased by approximately 50% when D(2)O replaced H(2)O as the solvent. From this, we conclude that hydrogen ions do not pass through M(2) as hydronium ions, but instead must interact with titratable groups that line the pore of the channel. M(2) currents measured in solutions of low buffer concentration (<15 mM in oocytes and <0.15 mM in CV-1 cells) were smaller than those studied in solutions of high buffer concentration. Furthermore, the reversal voltage measured in low buffer was shifted to a more negative voltage than in high buffer. Also, at a given pH, M(2) current amplitude in 15 mM buffer decreased when pH-pK(a) was increased by changing the buffer pK(a). Collectively, these results demonstrate that M(2) currents can be limited by external buffer capacity. The data presented in this study were also used to estimate the maximum single channel current of the M(2) ion channel, which was calculated to be on the order of 1-10 fA.

Delayed contractures induced by external cadmium ions in rat soleus muscle fibres.

Cd(2+)-induced contractures began with a delay of approximately =4 min after adding 3 mM Cd2+ to external solutions that contained Cl- as the major anion. Tension increased to approximately =20% of peak tetanic tension after 30 min and was maintained after Cd2+ washout. Tension developed more rapidly at higher [Cd2+] (up to 10 mM). There was a lack of correlation between the delay before the contracture and contracture tension: (1) tension was reduced by 2 mM CO2+ or 50 microM nifedipine, although the delay remained at approximately =4 min, and (2) the delay fell to seconds when Cd2+ was added in SO42- solutions, although tension was the same as in Cl- solutions. Since (SO4)2- solutions swell T-tubules, Cd2+ may enter the T-system before inducing contractures. Cd(2+)-induced contractures depended on external [Ca2+] since they were reduced when Ca2+ was omitted from solutions. The contractures did not depend on activation of excitation-contraction coupling, since tension was not altered when the voltage sensor was inactivated by depolarization in 40 mM K+. A small contracture developed with 3 mM Zn2+, but not 3 mM Co2+ or La3+. Both Cd2+ and Zn2+ activated the contractile proteins in skinned fibres. Cd(2+)-induced contractures may depend on external Cd2+ releasing Ca2+ from the sarcoplasmic reticulum (SR), or on Cd2+ entering the fibre, releasing Ca2+ from the SR and/or directly activating the contractile proteins.

Phase II clinical trials of cisplatin-then-paclitaxel and paclitaxel-then-cisplatin in patients with previously untreated advanced epithelial ovarian cancer.

PURPOSE: To examine the activity and safety of two sequentially scheduled chemotherapy regimens comprising four cycles of paclitaxel (pctx) 200 mg/m2/3 hours then four cycles ofcisplatin (cisDDP) 100 mg/m2, and vice versa, in patients with previously untreated advanced ovarian cancer. PATIENTS AND METHODS: Between January 1994 and February 1996, we recruited 30 patients to the pctx-then-cisDDP regimen and 29 to cisDDP-then-pctx, in parallel phase II trials. RESULTS: Both regimens were predictably active with responses seen in 22 of 30 patients (OR 74%; CR 27%, PR 47%) treated with pctx-then-cisDDP, as against 13 of 21 patients (OR 62%; CR 38%, PR 24%) treated with cisDDP-then-pctx. The OR rate to four cycles of pctx (induction) was 43%, with 27% disease progression; the OR to four cycles of cisDDP (induction) was 57%, with 5% progression. However, progression rates across both induction and consolidation phases were 16% (pctx-then-cisDDP) and 29% (cisDDP-then-pctx). Both regimens were unacceptably neurotoxic. II patients suffering grade 3 sensory neurotoxicity (5 on pctx-then-cisDDP, 6 on cisDDP-then-pctx) and 20 having grade 3 deafness (9 on pctx- then-cisDDP, 11 on cisDDP-then-pctx). CONCLUSION: The activity of these sequential regimens justifies their further development using the less neurotoxic platinum analogue carboplatin, perhaps combining paclitaxel with other platinum non-cross resistant drugs.

Effects of external cadmium ions on excitation-contraction coupling in rat soleus fibres.

The actions of external Cd2+ on the twitch and tetanic contractions, action potentials and potassium (K+) contractures of rat soleus muscle fibre bundles have been investigated. Cd2+ at 1-1.5 mM did not significantly alter tetanic tension, but increased twitch tension and increased the duration and overshoot of action potentials. At >/=3 mM, Cd2+ (1) depressed tetanic contractions and initially potentiated but later depressed twitches, (2) abolished the action potential overshoot, and (3) shifted peak K+ contracture tension to more positive membrane potentials. Twitch and tetanic contractions, and action potentials remained depressed when Cd2+ was washed out of the bath. The effects of Cd2+ on the twitch, tetanus and action potential were mimicked by Zn2+, while La3+ and Co2+ at 3 mM - or Mg2+ and Ca2+ at 30 mM - depressed peak twitch and tetanic tension, but did not potentiate twitches. The results suggest that: (1) Cd2+ and Zn2+ potentiate twitch tension by prolonging action potential depolarisation; (2) Cd2+ depresses twitch and tetanic tension by reducing the action potential overshoot, and causing a positive shift in the voltage dependence of contraction; and (3) the irreversible depression of action potential amplitude in rat soleus muscle is a specific property of Cd2+ and Zn2+ that is not shared by Co2+, Mg2+ or Ca2+.

Effects of ivermectin and midecamycin on ryanodine receptors and the Ca2+-ATPase in sarcoplasmic reticulum of rabbit and rat skeletal muscle.

1. Ryanodine receptor (RyR) Ca2+ channels in the sarcoplasmic reticulum (SR) of skeletal muscle are regulated by the 12 kDa FK506- (or rapamycin-) binding protein (FKBP12). Rapamycin can also activate RyR channels with FKBP12 removed, suggesting that compounds with macrocyclic lactone ring structures can directly activate RyRs. Here we tested this hypothesis using two other macrocyclic lactone compounds, ivermectin and midecamycin. 2. Rabbit skeletal RyRs were examined in lipid bilayers. Ivermectin (cis, 0.66-40 microM) activated six of eight native, four of four control-incubated and eleven of eleven FKBP12-'stripped' RyR channels. Midecamycin (cis, 10-30 microM) activated three of four single native channels, six of eight control-incubated channels and six of seven FKBP12-stripped channels. Activity declined when either drug was washed out. 3. Neither ivermectin nor midecamycin removed FKBP12 from RyRs. Western blots of terminal cisternae (TC), incubated for 15 min at 37 C with 40 microM ivermectin or midecamycin, showed normal amounts of FKBP12. In contrast, no FKBP12 was detected after incubation with 40 microM rapamycin. 4. Ivermectin reduced Ca2+ uptake by the SR Ca2+-Mg2+-ATPase. Ca2+ uptake by TC fell to approximately 40% in the presence of ivermectin (10 microM), both with and without 10 microM Ruthenium Red. Ca2+ uptake by longitudinal SR also fell to approximately 40% with 10 microM ivermectin. Midecamycin (10 microM) reduced Ca2+ uptake by TC vesicles to approximately 76% without Ruthenium Red and to approximately 90 % with Ruthenium Red. 5. The rate of rise of extravesicular [Ca2+] increased approximately 2-fold when 10 microM ivermectin was added to TC vesicles that had been partially loaded with Ca2+ and then Ca2+ uptake blocked by 200 nM thapsigargin. Ivermectin also potentiated caffeine-induced Ca2+ release to approximately 140% of control. These increases in Ca2+ release were not seen with midecamycin. 6. Ivermectin, but not midecamycin, reversibly reduced Ca2+ loading in four of six skinned rat extensor digitorum longus (EDL) fibres to approximately 90%, and reversibly increased submaximal caffeine-induced contraction in five of eight fibres by approximately 110% of control. Neither ivermectin nor midecamycin altered twitch or tetanic tension in intact EDL muscle fibres within 20 min of drug addition. 7. The results confirm the hypothesis that compounds with a macrocyclic lactone ring structure can directly activate RyRs. Unexpectedly, ivermectin also reduced Ca2+ uptake into the SR. These effects of ivermectin on SR Ca2+ handling may explain some effects of the macrolide drugs on mammals.

Depolarization accelerates the decay of K+ contractures in rat skeletal muscle fibers.

The experiments examine the effects of membrane potential on the time course of K+ contractures in small bundles of rat soleus and extensor digitorum longus (EDL) muscle fibers. Control K+ contractures were induced by exposure to a 200 mmol/L K+ solution in polarized fibers with a resting membrane potential of -83 mV (3.5 mmol/L K+), while test contractures were evoked with 200 mmol/L K+ from -46 mV, after 5, 10, and 30 min in a 30 mmol/L K+ conditioning solution. The decay times of the test K+ contracture in depolarized fibers were faster than those of the control K+ contracture in both soleus and EDL. A maximum reduction of 60% in the time for the contracture to decay from 90% to 10% was seen in soleus fibers after depolarizations lasting 10 min, while a reduction of 45% was seen in the decay time of EDL fibers after a 5-min depolarization. The amplitudes of the test contractures were 30% less than control after 5-min and 10-min depolarization and 50% less than control after 30 min. Analysis of the results suggests that the kinetics of excitation-contraction coupling may be altered in damaged muscle fibers.

The West Midlands epithelial ovarian cancer adjuvant therapy trial.

In a multicentre prospective randomized controlled trial, single agent cisplatinum was compared with whole abdomino-pelvic moving strip radiotherapy in the management of Stage IC-III epithelial ovarian cancer patients who had no macroscopic residual disease after primary surgery. Over a 6-year period 40 eligible patients were recruited, 15 of whom had Stage III disease. The overall 5-year survival was 60% with no significant survival difference between the treatment groups. Acute toxicity was common in both arms and six (11%) patients experienced significant long term disability.

Carboplatin and retroperitoneal fibrosis.

A patient treated for ovarian epithelial cancer by total abdominal hysterectomy (TAH), bilateral salpingo-oophorectomy (BSO), total omentectomy and five courses of single agent carboplatin chemotherapy, developed retroperitoneal fibrosis. This was diagnosed at exploratory laparotomy 6 months after completing treatment. No predisposing drug history existed in this patient. We believe that there have been no previous reports of an association between retro peritoneal fibrosis and carboplatin treatment.

Glycoprotein patterns in normal and malignant cervical tissue.

Glycoproteins from normal and malignant human cervix were studied using an organ culture system and compared by gel electrophoresis and autoradiography. Five glycoproteins of 178 kDa, 95 kDa, 93 kDa, 82 kDa and 38 kDa and 1 glycolipid (46 kDa) were detected more frequently in squamous carcinomas. Certain glycoproteins were shown to be oncofoetal and some had affinity for Concanavalin A (Con A). The 82 kDa glycoprotein was present in 16/17 squamous carcinomas but in only 1/13 normal cervices. This band represented a glycoprotein containing glucosamine, mannose, small quantities of methionine and no fucose. These preliminary results suggest that these glycoproteins and in particular the 82-kDa glycoprotein are worthy of further investigation and characterisation.