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STUDY OBJECTIVES: Recently, pulmonologists have performed thoracoscopy under local anesthesia using rigid thoracoscopes or flexible bronchoscopes. The latter allow greater access within the pleural cavity but are difficult to manipulate. The Olympus LTF semiflexible fiberoptic thoracoscope combines features of both instruments, having a solid body and a flexible terminal section. In the first study with this instrument, we evaluated ease of use and compared diagnostic yield with closed needle biopsy. PATIENTS: Twenty-four patients with pleural effusion were investigated. SETTING: Scottish University Hospital. DESIGN: Thoracoscopy was performed in the bronchoscopy suite after premedication with atropine and papaveretum. Following a standard Abram's needle biopsy, the LTF thoracoscope was inserted through a flexible introducer (Olympus Optical Co Ltd; Tokyo, Japan). The pleura was inspected and biopsy specimens were taken of suspicious areas. RESULTS: The final diagnosis was malignant pleural effusion in 16 of 24 patients. Ten of 16 were positive by Abram's biopsy, giving a sensitivity of 62%. Thirteen of 16 were positive by fiberoptic thoracoscopy, giving an improved sensitivity of 81%. The LTF thoracoscope was easy to use for pulmonologists experienced in rigid thoracoscopy and flexible bronchoscopy. Excellent views of the pleura were obtained from a single entry point. The procedure was well tolerated and no complications were encountered. CONCLUSION: The LTF thoracoscope allows excellent pleural access but a larger biopsy channel (currently 2 mm) might increase the accuracy of diagnosis.

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Circumvention of multidrug resistance in vitro by resistance modulators is well documented but their clinical use may be limited by effects on normal tissues. We have compared four resistance modifiers, both in terms of modulation of doxorubicin sensitivity in vitro and toxicity in vivo, in order to determine whether it is possible to select agents with clinical potential. Verapamil, D-verapamil and quinidine are all maximally active in the multidrug resistant cell line at about 7 microM and are not cytotoxic at this concentration. The tiapamil analogue Ro11-2933 is a highly potent resistance modulator such that at only 2 microM sensitization is greater than is seen with the other modulators at 7 microM. Since the ID50 concentration for Ro11-2933 is 17.7 microM (5-12-fold less than the other modifiers) we have used isobologram analysis to demonstrate that the interaction with doxorubicin is supra-additive and cannot be explained by additive toxicity. This method of analysis also revealed that when resistance modulation is related to the cytotoxicity of the modulator itself, all four modulators show comparable activity. On the other hand, measurement of the acute toxicity in mice of the modulators did reveal differences. The LD10 for verapamil (51 mg/kg) was about one third of that for quinidine (185 mg/kg) and this is consistent with the known maximum tolerated plasma levels in patients. Furthermore, whilst epirubicin alone was unable to reduce the growth rate of a multidrug resistant human tumour xenograft, the addition of quinidine, but not verapamil, at the maximum tolerated dose did do so. D-Verapamil was only about half as toxic as racemic verapamil and this too is consistent with clinical observations. The LD10 for Ro11-2933 (152 mg/kg) was comparable with that for quinidine. In the human tumour xenograft model maximal growth inhibition was observed with the combination of epirubicin and Ro11-2933 (45 mg/kg) and this degree of growth inhibition was comparable to that obtained with epirubicin alone in the drug sensitive xerografts. Ro11-2933 had no measurable effects on the plasma or tumour pharmacokinetics of epirubicin. These results suggest that it is possible to predict the clinical potential of a resistance modulator. Furthermore, Ro11-2933 is a promising agent for use in the clinic since maximal resistance modulation in vivo is observed at about one third of the LD10 dose.

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An account is given of an outbreak of malignant catarrhal fever which occurred in a 98-cow dairy herd. Ten animals died or were slaughtered and the disease was confirmed by clinical and histological examination. Serological tests for malignant catarrhal fever virus were positive in three of four animals. The diagnosis of malignant catarrhal fever was complicated by the presence of bovine virus diarrhoea virus infection in three of the early cases. The initial cases of malignant catarrhal fever occurred in a group of nine-month-old calves which were housed in an old milking parlour with 19 pedigree Suffolk ewes at lambing time. Later cases occurred in two adult cows and in two heifers. Investigations of the remainder of the herd for evidence of bovine virus diarrhoea virus did not reveal the presence of any persistently infected cattle. Serological examinations for antibody to malignant catarrhal fever and bovine virus diarrhoea virus were carried out on the 19 Suffolk ewes. Six of them had neutralising antibody titres to malignant catarrhal fever virus and three were positive in the indirect immunofluorescence test. The possible roles of bovine virus

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Retinal detachment was observed as a cause of blindness in small numbers of reared pheasants in widely separated geographical areas. Lesions were bilateral but asymmetrical in 16 birds. In three pheasants only one eye was affected. Clinical signs were first noticed at 5 weeks of age. Affected birds were blind by the time they were mature. Early lesions comprised subretinal fluid and degeneration of the vitreous body. Following separation of the retina at the junction of the pigmented epithelium and photoreceptors, adhesions took place between the detached tissue and both the pecten and lens. Peripheral cystoid defects were seen concomitantly in the retinas of seven pheasants but these were bilateral in only two individuals. The cause of the disease is unknown.

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Mycoplasma bovis infection was eradicated from a naturally infected dairy herd in Great Britain by a programme of identification, segregation and culling of infected animals. A series of group and whole milking herd tests was carried out over a period of 15 months, followed by a whole herd nasal swabbing. Cows were also sampled after calving and at drying off and bulk tanks were sampled at weekly intervals during the same period and for a further nine months. Fifty-nine cows were identified as excretors, the majority in group or herd tests, but five after calving and three at drying off. Eight of the original clinical cases were retained in the herd, after repeated negative test results. Bulk tank sampling was found to be extremely useful in detecting infection even down to one cow in a milking herd of 300. The value of milking hygiene and the indications for eradication are also discussed.

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Brucella abortus infection in the bitch, associated with an aborted bovine fetus, is described. Clinical signs were absent, but the organism was isolated from many sites in the body, including the urine, after death. The response of the dog to B. abortus infection and its possible role as a vector of the disease is discussed.

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Salmonella aberdeen was established as the cause of illness in 30 out of a herd of 90 milking cows. The illness was only moderately severe, and all animals responded to treatment.The source of infection was considered to be human sewage effluent overflowing onto grazing land. There was no report of human infection in the area from which the effluent came.

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