A nonlinear system model for electrospinning sub-100 nm polyacrylonitrile fibres.

Solutions of polyacrylonitrile (PAN) were electrospun using a range of process parameters, resulting in fibre diameters from 10 to 320 nm. A nonlinear neural network system model was used to analyse the dependence of the fibre diameter on the process parameters, and used to simulate conditions for electrospinning 40-60 nm diameter fibres. These results indicated that flow rate is most important for determining fibre diameter. It was not possible to find the appropriate conditions for electrospinning sub-25 nm fibres. Precise control of the ambient temperature and relative humidity will be critical to producing electrospun fibres that are sub-25 nm. Further, it is unlikely that sub-25 nm fibres will be produced without significant changes in the electrospinning apparatus, for example, by use of focusing and jet-steering fields, alternate carrier gases to modify the discharge characteristics, or patterned electrospinning.

Association of clonal T-cell large granular lymphocyte disease and paroxysmal nocturnal haemoglobinuria (PNH): further evidence for a pathogenetic link between T cells, aplastic anaemia and PNH.

There is mounting evidence to suggest that T-cell-mediated suppression of haemopoiesis is a pathogenetic mechanism in three bone marrow failure syndromes: aplastic anaemia (AA), paroxysmal nocturnal haemoglobinuria (PNH) and myelodysplasia (MDS). T-cell microclones can be detected by sensitive polymerase chain reaction (PCR)-based methods in all three disorders. Recently, larger clonal populations of T-cell large granular lymphocytes (T-LGLs) have been observed in some patients with AA and MDS. Here, we report the development of a large clonal T-LGL population in a patient with bona fide PNH. In this patient, we defined part of the sequence of the T-cell receptor (TCR) beta-chain gene, and we have shown that the large T-LGL population emerged from a background of multiple smaller T-cell clones. Thus, T-LGL clones in AA, MDS and PNH probably expand as a result of antigenic stimulation. It is postulated that the antigen driving clonal T-cell proliferations in these disorders exists on haemopoietic stem cells.

The Women's Health Curriculum by a problem-based learning method for medical students at the University of California, San Francisco.

OBJECTIVES: Our objectives were to (1) expand and strengthen the women's health curriculum at the University of California, San Francisco, and (2) evaluate the responses of both medical students and faculty to this curriculum. STUDY DESIGN: A written evaluation of the curriculum in women's health was completed by both students and faculty. Variables studied included mean scores of cases, the overall course score, and the preferences of medical students for faculty specialty in teaching the small groups. RESULTS: The overall course evaluation score was 7.81 (range 1 to 10). For those students who had both faculty from internal medicine or family medicine and obstetrics and gynecology, there was a strong preference that obstetrician-gynecologists teach the majority of the cases. CONCLUSIONS: The new case-based curriculum in women's health was enthusiastically received by both medical students and faculty.

Serological studies on British isolates of the Sejroe serogroup of leptospira. II. An evaluation of the factor analysis method of identifying leptospires using strains belonging to the Sejroe serogroup.

Twelve British isolates of leptospira belonging to the Sejroe serogroup were examined using a series of six factor sera prepared by a number of different absorption methods. Ten of the isolates were identified as Leptospira interrogans serovar hardjo and two as L. interrogans serovar saxkoebing. These isolates had previously been identified using the cross agglutination absorption method.

Serological studies of British leptospiral isolates of the Sejroe serogroup. III. The distribution of leptospires of the Sejroe serogroup in the British Isles.

Some 94 strains of leptospires belonging to the Sejroe serogroup isolated in the British Isles were identified to the serovar level using specific factor sera. Seventy strains were identified as Leptospira interrogans serovar hardjo, 66 from cattle, 2 from pigs and 1 each from a sheep foetus and a human. Twenty-four strains were identified as L. interrogans serovar saxkoebing, most strains were isolated from either wood mice, bank or field voles but strains were also isolated from badgers, a fox and a dog.

Serological studies on British leptospiral isolates of the Sejroe serogroup. I. The identification of British isolates of the Sejroe serogroup by the cross agglutinin absorption test.

Using the cross agglutinin absorption test 12 British leptospiral isolates of the Sejroe serogroup were identified to serovar level. Six strains isolated from cattle, two from pigs and one from a human were identified as Leptospira interrogans serovar hardjo. Two isolates from wildlife were identified as Leptospira interrogans serovar saxkoebing. One further strain isolated from wildlife closely resembled serovar saxkoebing, but specific identification was not possible. These are the first reported isolations of serovar saxkoebing in the United Kingdom. The problems associated with the cross agglutinin absorption test, and possible alternative typing procedures are discussed.

Infection of free-living carnivores with leptospires of the Australis serogroup.

Leptospires belonging to the Australis serogroup were isolated from badgers (Meles meles), mink (Lutreola lutreola) and a fox (Vulpes vulpes). Most isolates were identified by cross-agglutination absorption as serovar muenchen but one isolate from a fox from Surrey and one isolate from a badger from Northern Ireland were identified as serovar bratislava. Maintenance of serovar muenchen by a wide range of free-living species is an ecological condition unique to Great Britain.

Leptospira interrogans serovar hardjo in pigs: a new host-parasite relationship in the United Kingdom.

The first isolations of Leptospira interrogans serovar hardjo from pigs are recorded. Evidence that hardjo may be a sporadic cause of porcine reproductive disease is presented.

Isolation of Leptospira interrogans serovar hardjo from a viable premature calf.

A severe outbreak of agalactia in a dairy herd of 80 cows was followed by six premature calvings and an abortion. Serological and bacteriological studies identified Leptospira hardjo as the probable cause. A leptospire isolated from the kidney of a premature calf killed seven weeks post partum was identified as hardjo and it is probable that this infection was acquired in utero. The maintenance of such an infection for a considerable period after birth has not been previously described and may play a role in the transmission of hardjo to susceptible in-contact animals.

Serovar identification of leptospires of the Australis serogroup isolated from free-living and domestic species in the United Kingdom.

Eighteen isolates from the Australis serogroup from free-living and domestic animals were identified using the cross agglutination absorption test. Serovar muenchen was found only in England and Wales in wood mice, short tailed and bank voles, a grey squirrel and a pig. Serovar bratislava was found in hedgehogs in England, Wales and Northern Ireland and also in a brown rat from Northern Ireland. Serovar bratislava was isolated from sheep in both England and Northern Ireland and from horses in Northern Ireland. The distribution of these serovars in relation to possible maintenance hosts is discussed.

Identification of a reservoir of leptospira interrogans serovar muenchen in voles (Microtus agrestis and Clethrionomys glareolus) in England.

Infection with leptospires of the Australis serogroup is widespread in voles in Southern England and the serovar identification of five randomly-selected isolates was determined by cross agglutination absorption. Two isolates from short-tailed voles (Microtus agrestis) and three isolates from bank voles (Clethrionomys glareolus) were all identified as serovar muenchen. The only previous isolation of this serovar is that from a human in Germany.

Isolation of Leptospira interrogans serovar muenchen from a sow with a history of abortion.

The isolation of Leptospira interrogans serovar muenchen from a sow which aborted in the first third of pregnancy is described. Isolation was achieved only in media containing a rabbit serum additive and identification was determined by cross-agglutination absorption. A high degree of cross-reactivity was found with reference antisera of the Australis serogroup. Serovar muenchen has not previously been reported in animals and may be responsible for a proportion of the titres to antigens of the Australis serogroup that have recently been reported in pigs in England.

Failure to demonstrate the maintenance of leptospires by house mice (Mus musculus) in the south east of England.

A total of 272 house mice (Mus musculus) were trapped in farm buildings at four widely separated locations of south east England and examined for serological and bacteriological evidence of leptospiral infection. Only two low titres to autumnalis antigen (1:20 and 1:40) were recorded and all mice were bacteriologically negative. The absence of leptospiral infection in the house mouse in south east England is an interesting ecological finding, as this species is a maintenance host for ballum in many countries and also a common carrier of several other serovars. The source of ballum infections in domestic stock in England remains unknown.

Serological survey of leptospiral antibodies in sheep from England and Wales.

A total of 3722 sera was obtained from 188 flocks widely distributed throughout England and Wales; three sera were randomly selected from each flock and tested in the microscopic agglutination test for leptospiral antibodies. Infection with leptospires of the Hebdomadis serogroup was found to the widespread and it is probable that the infecting serovar is hardjo. The prevalence of hardjo titres in the random survey was 6.4 per cent and within-herd prevalences ranged up to 94.4 per cent. Titres to autumnalis antigen were found in 7.3 per cent of sera and evidence is presented that suggests a proportion of these titres are cross-reactions with agglutinins stimulated by infection with leptospires from other serogroups. Titres to bratislava antigen (Australis serogroup) were found in 3.4 per cent of sera. Within-herd prevalences of autumnalis and bratislava titres did not range above 16.7 per cent and 26.3 per cent respectively.

Serological and bacteriological survey of leptospiral infection in pigs in southern England.

A total of 597 pigs were examined for serological and bacteriological evidence of leptospiral infection. The sample comprised 189 porkers, 205 baconers and 203 sows. Sera were tested against 17 antigens from 16 serogroups and the overall prevalence of titres was 15.7 per cent. The lowest prevalence of titres was found in porkers (10.0 per cent). The highest prevalence of titres to an individual antigen was recorded with bratislava, a member of the Australis serogroup, with 12.2 per cent of pigs positive. Copenhageni titres were present in 1.8 per cent of the sera and sporadic titres were recorded to various other antigens. Leptospires were isolated from five pigs. Four isolates were identified as belonging to the Icterohaemorrhagiae serogroup and one to the Hebdomadis serogroup. The serological to bacteriological ratio for the Icterohaemorrhagiae serogroup was 11:4. The virtual absence of titres to pomona and tarassovi, the two serovars most commonly maintained by porcine populations in other countries, confirms the results of earlier serological surveys.

Mastitis and abortion in dairy cattle associated with Leptospira of the serotype hardjo.

Following a sudden drop in milk yield in a large dairy herd, leptospiral mastitis due to serotype hardjo was diagnosed serologically and by isolation of the organism from the milk and urine of affected cows. Two milkers subsequently became ill and developed titres to the Hebdomadis serogroup. During the same period the neighbouring herd experienced poor milking performance and a series of abortions and serological evidence suggested recent hardjo infection. The common source of infection appeared to be infected down calving heifers.