Purification and preliminary characterisation of a pathogenic strain of infectious bursal disease virus

A pathogenic strain of infectious bursal disease virus has been purified by density gradient centrifugation, principally on sucrose and tartrate gradients. Examination of gradient peak fractions by electron microscopy has revealed two populations of particles of average size 62 nm and 20 nm, which band together on sucrose and tartrate gradients. Purified virus has been shown to reproduce the typical symptoms and lesions of infectious bursal disease. The possible classification of the larger virus particle in the diplornavirus group and the origin of the smaller particle are discussed.

Avian paramyxoviruses of PMV-3 serotype in British turkeys

Serological testing of turkey flocks in Great Britain was undertaken as a result of the isolation of an avian paramyxovirus of serotype PMV-3 from turkeys in 1981 (Macpherson et al., 1983). Turkeys on two of four farms with egg production problems examined for PMV-3 haemagglutination inhibition (HI) antibodies in 1981 were positive. Turkeys on 34 farms were tested for PMV-3 antibodies in 1982. Seven of 16 flocks showing egg production problems and/or respiratory disease were considered positive for PMV-3 (mean log(2) HI titre >/= 2.5), but five of 18 flocks with no reported disease were also positive for PMV-3 antibodies. On one turkey farm the appearance of PMV-3 antibodies and an isolation of a PMV-3 virus coincided with egg production problems. Analysis of HI titres in turkeys vaccinated against Newcastle disease virus (NDV) and unvaccinated birds suggested that significant NDV HI titres are unlikely to be recorded as a result of PMV-3 virus infections of unvaccinated birds. However, while NDV vaccination prior to PMV-3 infection apparently caused slight suppression of the PMV-3 immune response, the HI titres to NDV were boosted considerably in direct relationship to the PMV-3 titre.

Problems of population structure exemplified by the invasive tropical shrub Parkinsonia aculeata l. in northern Australia

Age-class frequency distributions are valuable means of describing plant populations because they can be used to infer population history. Variables other than age are also often used to describe plant populations, either because they more accurately reflect an attribute of interest, or because it is difficult to determine age. However, interpretation of frequency distributions based on variables other than age can be problematic. We discuss these problems and illustrate them using data from six populations of the invasive rangeland shrub Parkinsonia aculeata L. We used three different measures of plant size: height, canopy diameter and stem cross-sectional area. Structures based on these measures were compared with structures based on three different estimates of above-ground biomass derived from them. For each variable, structures differed greatly between populations, and for each population, they were strongly dependent on the variable used to describe it. Population structures based on three-dimensional variables (above-ground biomass) tend to be more strongly positively skewed than those based on two-dimensional (area) measures of plant size. These in turn are more strongly positively skewed than those based on one-dimensional (height, diameter) measures. The statistical basis of this general phenomenon is discussed. The results highlight the difficulties of deriving histories and projecting futures of populations from size-class frequency distributions without accompanying knowledge of the temporal patterns of change in size variables as plants grow.

Sequential spread of Campylobacter infection in a multipen broiler house

Generally, colonization with Campylobacter jejuni is first detected in broilers 2-3 wk after hatching. Once introduced into a flock, this infection spreads very rapidly. The sources and routes of transmission of C. jejuni in broilers remain debatable. In this study, the spread of infection was monitored in a commercial multipen broiler house in which birds were contained in discrete groups and sampled sequentially. Colonization was monitored in two broiler flocks up to slaughter. Serotyping and fla typing methods were applied to differentiate all the C. jejuni strains isolated. In flock 1, colonization was first detected at 32 days of age in birds located at the rear of the house. By 40 days, nearly all the birds were infected with the same strain (fla type 1.9). However, at 46 days of age, a second strain (fla type 3.7) was detected in some of the birds. These birds were also located toward the rear of the house. In flock 2, infection was detected at 5 wk of age. This infection was once again first detected in birds located at the rear of the house. In this flock, only a single fla type (1.1) was isolated throughout. A survey of the broiler house relative to the location of first point of infection indicated the use of an entrance door unprotected by boot dips. However, securing this door during the second flock study did not prevent infection.

Measurement of the healing of venous ulcers

The surface area of 99 leg ulcers was measured from a scaled photograph using a computerized ultrasonic digitizer. This was compared with the area obtained by multiplying the two maximal perpendicular diameters of each ulcer. There was an extremely good correlation between these two methods (r = 0.951). Seventy-four patients were followed up as part of a placebo-controlled double-blind study. In this study, treatment was assessed by the time taken for the ulcerated limb to heal completely. The initial ulcer size was found to be a weak predictor of subsequent ulcer healing (r = 0.49). The healing rates of individual ulcers calculated over 1 month intervals from presentation proved to be a poor predictor of the time required for complete ulcer healing (Spearman rank correlation coefficients ranged from 0.15 to 0.61). The healing curves of individual ulcers showed considerable fluctuations during the process of healing. The product of the maximal dimensions of an ulcer provides an easy and accurate method of monitoring treatment. The reduction in ulcer size within a set time interval, used in many ulcer studies, is a poor predictor of eventual ulcer healing. The percentage of ulcers completely healed within a pre-determined time interval is a better method of assessing new treatments.

Influence of phlebographic abnormalities on the natural history of venous ulceration

Eighty-five limbs in 73 patients with a healed venous ulcer were assessed by ascending and descending phlebography, foot volume plethysmography and transcutaneous oxygen measurements. Forty-four limbs had post-thrombotic changes on ascending phlebography. In 24 (28 per cent) these extended into the femoral vein, while in 20 (24 per cent) only the calf veins were involved. In the 41 limbs (48 per cent) with normal deep veins on ascending phlebography, 11 had evidence of localized incompetence of the calf communicating veins, 14 had either long saphenous incompetence, deep vein reflux to the level of the knee or below, or both of these abnormalities, and 16 limbs had no phlebographic abnormalities. However all limbs had a decreased half volume refilling time on foot volume plethysmography. Limbs with post-thrombotic changes extending into the femoral vein were associated with a significantly longer history of ulceration and more ulcer recurrences than limbs with calf vein damage (P less than 0.05 for each) and limbs with normal deep veins (P less than 0.01 for each). However, these limbs did not have lower transcutaneous oxygen ratios or longer times to achieve ulcer healing. Ascending phlebography identified a group of limbs with extensive post-thrombotic changes in which there was a higher incidence of ulcer breakdown, but this was not associated with a delay in ulcer healing.

Transcutaneous oxygen tensions in assessing the treatment of healed venous ulcers

Transcutaneous oxygen tension (Ptc,O2) was assessed as an indicator of risk of reulceration in 68 limbs with healed venous ulcers. Ptc,O2 was also used to assess two methods of ulcer prophylaxis. Measurements were made over the gaiter skin, the healed ulcer and the upper arm. The results were expressed as a ratio of the lower limb readings over those taken from the arm. Patients were randomized, after the ulcer had healed, to elastic stockings and stanozolol, or elastic stockings and surgical ligation of incompetent superficial veins. Patients who declined to participate in the study were prescribed elastic stockings only. Those limbs remaining healed at 12 months had Ptc,O2 ratios remeasured. The Ptc,O2 ratios from limbs that reulcerated were not significantly lower than those from limbs remaining healed. The Ptc,O2 ratio was significantly increased in limbs treated by stanozolol and elastic stockings (P less than 0.05) and by surgery and elastic stockings (P less than 0.05). There was no significant increase in Ptc,O2 in limbs treated by elastic stockings alone. In those treated by surgery and elastic stockings, there was a significant improvement in limbs with normal deep veins (P less than 0.01), but not in limbs with post-thrombotic changes on ascending phlebography. Although these two methods of ulcer prophylaxis improve the Ptc,O2 ratio, a high ratio has not been shown to be beneficial in preventing ulcer recurrence.

Observations on swollen head syndrome in broiler and broiler breeder chickens

Chickens on 14 broiler breeder farms were examined at various times throughout their laying cycle. Antibodies to the turkey rhinotracheitis virus were common although they were not always accompanied by clinical signs of the swollen head syndrome. Ninety-nine broiler flocks were tested of which only 20 were serologically positive to the virus. Some of these infections were subclinical. On nine farms where swollen head syndrome occurred several successive flocks were sampled; the syndrome occurred intermittently.

Religious affiliations in mental health research samples as compared with national samples

Religious affiliations of patients in research samples in four major psychiatric journals for the years 1978-1982 were compared with those reported in national samples. Protestants and the unaffiliated were underrepresented, whereas Jewish persons were overrepresented. Catholics used mental health services in proportions similar to their presence in the population at large. These findings suggest that religious affiliation may influence the use of mental health services.

Calf pump function in patients with healed venous ulcers is not improved by surgery to the communicating veins or by elastic stockings

Calf muscle pump function was assessed in 41 limbs after venous ulcers had healed. Treatment was then randomized either to ligation of incompetent lower leg communicating veins and ablation of incompetent superficial veins combined with permanent graduated compression elastic stockings, or to graduated compression elastic stockings only. Half volume refilling time (TV1/2) and relative expelled volume (EVrel) measured on foot volume plethysmography were used to assess calf muscle pump function. This was repeated after 12 months. The initial TV1/2 and EVrel were significantly lower than for normal limbs. There was no significant improvement in TV1/2 in either treatment group (Student's t test, P = 0.78, P = 0.19). EVrel did not improve significantly in limbs treated with elastic stockings alone (P = 0.94), but there was a slight but significant improvement in EVrel in limbs treated with surgery and elastic stockings (P = 0.048); however, this was still significantly below the normal range (P less than 0.001). In limbs without phlebographic evidence of post-thrombotic changes, treated with the combination of surgery and elastic stockings, there was a significant improvement in EVrel (P = 0.035), but no improvement was found in limbs with post-thrombotic changes. This small but significant improvement in EVrel in limbs without post-thrombotic changes treated by surgery and elastic stockings may explain the reduced incidence of reulceration that has been found following surgical eradication of the superficial and communicating veins.

Changes in the apparently normal limb in unilateral venous ulceration

Forty-seven patients with unilateral venous ulceration have been investigated to determine if any abnormalities were present in the contralateral limbs which had not had lipodermatosclerosis or ulceration. Ascending phlebography in the non-ulcerated limbs showed post-thrombotic changes in 28 per cent and incompetent lower leg communicating veins in 19 per cent. This incidence was not significantly different to the limbs with healed ulceration (45 and 23 per cent respectively, chi 2 test, P = 0.10). Half volume refilling time measured by foot volumetry suggested that 79 per cent of the non-ulcerated limbs had evidence of deep vein incompetence or incompetent lower leg communicating veins, which was again similar to the incidence in the previously ulcerated limbs (85 per cent). Transcutaneous oxygen readings, expressed as a ratio of a reading at a standard site in the gaiter region of the leg over a reading from the upper arm, were significantly lower in non-ulcerated limbs (mean 0.84 +/- 0.26 s.d.) than in a cohort of age and sex matched controls (mean 1.02 +/- 0.14, Student's t test, P less than 0.001), and significantly higher than in previously ulcerated limbs (mean 0.68 +/- 0.31, P less than 0.01). Abnormalities in venous anatomy and function have been shown, in conjunction with evidence of reduced oxygen diffusion, through the gaiter skin before overt skin changes develop.

Tissue plasminogen activators in breast cancer

Increased levels of tissue fibrinolytic activity have been detected in some malignant tumours and they have been implicated in metastatic spread. We have investigated tissue plasminogen activator (tPA) and urokinase (UK) in 26 breast carcinomas and 13 benign breast biopsies. Tissue extracts were analysed for overall fibrinolytic activity on fibrin plates and by fibrin-overlay zymography after electrophoresis on SDS-PAG. Supernatants of the extracts were analysed by an antigenic immunoassay (ELISA) and a functional bioimmunoassay (BIA) using polyclonal antibodies. Total ELISA and BIA results correlated (P less than 0.001) and all the tissues contained similar tPA levels. Malignant extracts contained significantly increased UK compared with benign extracts (1.60 +/- 0.37 iu, 0.36 +/- 0.16 iu; P less than 0.002). Zymography showed no high molecular weight inhibitor complexes and UK was almost exclusively confined to the malignant tissues (P much less than 0.02). The results suggest that malignant transformation of breast tissue is associated with the significantly increased production of UK. This may be responsible for the characteristics of malignancy or it may be a growth factor.

A study of the mechanical properties of fresh and preserved human femoral vein wall and valve cusps

In the hope that some varieties of the post-phlebitic syndrome might be treated by implanting a preserved vein valve, studies have been made of the mechanical properties of vein valves and vein wall before and after preservation with glutaraldehyde. The ultimate tensile strength (breaking stress) and strain (extensibility) of strips of vein wall and valve leaflet were measured with a Nene tensiometer. The ultimate tensile strength of valve leaflet was found to be twice that of vein wall. Preservation in glutaraldehyde (0.2 per cent, pH 7.4, for 7 days) with valve cusps closed by a minimum head of pressure caused no change in breaking stress or extensibility.

Abnormal fibrinolysis: the cause of lipodermatosclerosis or "chronic cellulitis" in patients with primary lymphedema

Blood fibrinolytic activity was measured in 20 patients with primary lymphedema, ten without and ten with skin changes usually attributed to "chronic cellulitis". The patients with abnormal skin showed reduced fibrinolytic activity, a finding previously described in patients with chronic venous disease and lipodermatosclerosis . It is postulated that changes of "chronic cellulitis" are identical to lipodermatosclerosis and are produced by a similar mechanism, namely reduced fibrinolysis.

Specific B lymphocyte suppression by infectious bursal agent (Gumboro disease virus) in chickens

Chickens infected experimentally with infectious bursal agent (IBA) during embryonation or early after hatching show a severe depression of bursa-dependent lymphoid components, and associated immune functions. Data presented here and elsewhere show that the degree of B cell suppression correlates with the time of infection. This would be compatible with a virus-induced block in B lymphocyte differentiation. Accordingly, the virus may be cytopathic for early (bursal) but not late (circulating) B lymphocytes or, more likely, the virus inactivates those non-lymphoid bursal cells mediating lymphocyte differentiation.

Preliminary characterisation of paramyxovirus isolated from a parrot

A virus, designated 0121, which was isolated from a parrot, was shown to be a paramyxovirus, which was serologically related to the paramyxoviruses Bangor/flinch/N. Ireland/73 (Bangor) and Yucaipa/chicken/California/60(PMY). However, the 0121 virus differed in several properties from both the PMY and the Bangor viruses. The virus was not pathogenic for chickens. I was designated Paramyxovirus: Parrot/England/0121/74.

Infectious bursal disease agent: morphology by negative stain electron microscopy

The virus of infectious bursal disease of chickens was studied by immune electron microscopy. Negatively-stained preparations revealed morphological similarities with both the bluetongue virus group, and the virus of infectious pancreatic necrosis of trout. Results indicated that the small particle found in such preparations is a degradation product of the large particle.

A case of polytetrafluoroethylene poisoning in cockatiels accompanied by polymer fume fever in the owner

Five cocatiels (Nymphicus hollandicus) died within 30 minutes following exposure to fumes from a frying pan coated with the "non-stick" plastic polytetrafluoroethylene (PTFE) that had accidentally overheated. Within an hour the owner developed symptoms of "polymer fume fever" but recovered in the next 24 hours. Clinical signs and post mortem lesions of the cockatiels are described and reference is made to the unusual susceptibility of parakeets to the pyrolysis products of frying pans coated with PTFE.