1028 OLDER PERSON’S ASSESSMENT SERVICE (OPAS): DELIVERING COMPREHENSIVE GERIATRIC ASSESSMENT (CGA) IN THE EMERGENCY DEPARTMENT (ED)

Introduction

Innovative models of service delivery are required to provide Comprehensive Geriatric Assessment for older patients presenting to the Emergency Department with frailty syndromes.

Method

In 2018, the Older Person’s Assessment Service began a liaison service to the ED, taking referrals from the medical and ED teams for patients who presented with frailty syndromes (falls, cognitive impairment, care dependence, polypharmacy). The service saw 437 patients April–August 2018. 76% of the patients assessed were discharged by utilising available community services, rapid access outpatient follow up and inpatient reablement off the acute site. The service was estimated to avoid 50–80 admissions per month to medicine (saving 17–23 beds a year) and was commissioned as a permanent service. Phase 2 In 2020, a dedicated unit within ED was allocated to OPAS, enabling the acceptance of patients directly from triage and from the Ambulance Service by direct referral. This provided rapid access to specialist assessment, continued access to Elderly Care services, avoided exposure to coronavirus related admissions and the risks of nosocomial infection associated with admission. The service operates from 8 am-4 pm on weekdays.

Results

Between June 2020 and October 2021, the service saw 1,173 new patients. 988 patients (84.5%) were discharged off the acute site on the day of assessment. 68 (5.79%) patients were admitted to other facilities run by the Health Board (e.g Inpatient Reablement). The average age of an OPAS patient was 83 yrs and had a CFS > 5. Readmission rate at 14 days was 4% (47).Of the 253 patients who were admitted to an inpatient setting, 13.5% (35) contracted nosocomial covid-19.

Conclusion

The service has been supported and funded to expand into extended weekday hours as a result of this success and there are plans for future 7 day working.

Integration of e-learning resources into a medical school curriculum

BACKGROUND

E-learning has the potential to make important contributions to medical education, but there has been limited study of a blended approach in which the digital resources are introduced alongside traditional teaching methods such as lectures.

METHODS

We describe the successful embedding of an e-learning resource into 3 of the 5 weeks of cardiovascular system teaching for 164 first-year medical students by providing scheduled slots in the timetables. A questionnaire completed by the students at the end of the 5 weeks had a response rate of 66%. Students varied in how they made use of the resource, some systematically working through it and others browsing and studying sections felt to be personally most relevant.

RESULTS

Almost all (96%) rated the e-learning resources as probably or definitely of value: they particularly valued interactive activities, animations, video demonstrations, video clips of experts and self-assessment exercises. Graduate students had a significantly more favourable assessment of the e-learning resources than their undergraduate colleagues, while female students felt the value in supporting existing learning opportunities more strongly than male students.

CONCLUSIONS

It should not be assumed that all students will choose to use an e-learning resource in the same way and instructional design should enable alternative approaches. The sequence in which the e-learning resource is used in relation to the other learning opportunities, such as lectures and PBL group discussions, may be important and merits further consideration. The experiences reported in this study provide encouragement and pointers for others engaged in the integration of e-learning in their curriculum.

The effect of sward surface height on the response to mixed grazing by cattle and sheep

An experiment was conducted to examine the effects of mixed grazing of sheep plus cattle under continuous stocking of permanent pasture at different sward heights. The experiment had a 2×3 factorial design, with two sward surface heights (4–5 and 8–10 cm) and three combinations of animal species viz., sheep only, cattle only and sheep plus cattle. There were two replicate plots of each treatment combination and the experiment was conducted over 2 years consecutively. The sheep were Beulah Speckled Face ewes and their single Suffolk-cross lambs while the cattle were yearling Charolais-cross steers. Six ‘core’ steers and six ‘core’ ewes and their lambs grazed plots, as appropriately, while additional, non-experimental steers and ewes and their lambs were used to maintain sward heights. Each year the steers and the ewes grazed the pastures from May to October, while lambs were weaned and removed each year from the experiment in July. There was no significant effect of mixed grazing on live-weight gain of steers, but ewes had significantly higher live-weight gains on the sheep plus cattle treatment than on the sheep-only treatment (82 v. 61 g/day;P<0·001). The live-weight gain of the lambs was higher on the mixed grazing treatment than on the sheep only treatment on the 8–10 cm sward height treatment (243 v. 212 g/day;P<0·05) but there was no significant difference on the 4–5 cm sward height treatment (260 v. 250 g/day;P>0·05). The total output of live-weight gain per ha from steers, ewes and lambs was not significantly affected by animal species combination. It is concluded that while output per ha is not enhanced by mixed grazing by sheep and cattle when sward height is controlled, the live-weight gain of ewes is increased and the live-weight gain of lambs can be increased on taller swards.

The effect of mixed or sequential grazing of cattle and sheep on the faecal egg counts and growth rates of weaned lambs when treated with anthelmintics

An experiment was conducted over two successive years (2002 and 2003) to investigate the effects of grazing improved permanent pasture (mainly perennial ryegrass/white clover) by cattle or sheep, either sequentially or mixed, on the faecal egg counts and growth rates of weaned lambs when treated with anthelmintics. The grazing season was divided into two parts, May-July then July-October, relating to the pre- and post-weaning of the lambs. Four grazing regimes, replicated three times, were compared: (1) sheep only from May to October (SS); (2) cattle May to July followed by lambs until October (C/S); (3) cattle and sheep May to July followed by lambs until October (C+S/S); and (4) cattle and sheep May to July followed by cattle and lambs until October (C+S/C+S). Sward height was maintained at 6 cm using a "put and take" stocking system. At weaning, lambs were weighed and treated with an anthelmintic (0.08% ivermectin drench, Oramec) before being allocated to plots. They were then weighed and drenched every 28 days until the end of the experiment (Day 84). Faecal egg counts (FEC) were measured in all lambs immediately prior to each anthelmintic treatment. In 2002 and 2003, there were differences between the groups in FEC, with the SS lambs having the highest values and C/S lambs the lowest (P<0.01). There were also differences in the rate of liveweight gain of the lambs in each of the study years: for this parameter SS lambs had the lowest growth rate but the fastest growth was in C+S/C+S lambs not C/S lambs (P<0.01), indicating that these differences were due to factors other than parasite infection. Overall, sequential grazing of pastures with cattle then sheep reduced the faecal egg counts in lambs regularly treated with anthelmintics when compared with lambs grazing in mixed systems with cattle and sheep or with sheep only systems, however, the highest growth rates were observed in lambs in the mixed cattle/sheep grazing system throughout.

Isolation and Characterization of the ALP1 Protease from Aspergillus fumigatus and Its Protein Inhibitor from Physarium polycephalum

It is known that Aspergillus fumigatus secretes a serine protease ALP1 of the subtilisin family in the presence of extracellular protein substrates. We found conditions of A. fumigatus culturing that provide a high ALP1 activity inside cells without induction by extracellular proteins. The identity of the properties of the secreted and intracellular enzymes was shown. A thermostable protein inhibitor of the ALP1 protease was isolated from the plasmodium of the myxomycete Physarum polycephalum. Its molecular mass is 32-33 kDa. The inhibitor inhibits the ALP1 protease activity with IC50 of 0.14 microM. This protein was also shown to be a less efficient inhibitor of the activity of HIV-1 protease (IC50 2.5 microM). The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 3; see also http://www.maik.ru.

Systemic haemostasis after intermittent pneumatic compression. Clues for the investigation of DVT prophylaxis and travellers thrombosis

Intermittent pneumatic compression (IPC) is known to provide effective prophylaxis against post-surgical deep-vein thrombosis (DVT), and other procedures based on reducing venous stasis have been promoted recently to minimize the risk of thromboembolism after long-haul travel ('travellers thrombosis'). This study sought to measure the effects of IPC on systemic haemostasis, which are currently disputed. IPC was applied for 120 min on 21 male, non-smoking volunteers ranging in age from 19 to 47 years. IPC promoted a significant increase in global fibrinolytic potential. Levels of urokinase plasminogen activator activity (uPA) measured using an amidolytic assay were raised after IPC. However, enzyme-linked immunosorbent assays (ELISA) of uPA antigen, and the activities of tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) were not statistically different from those in control experiments. IPC led to highly significant falls in factor VIIa, associated with increased levels of tissue factor pathway inhibitor (TFPI). IPC enhances fibrinolysis and suppresses procoagulant activation. Measurements of specific fibrinolytic components do not reflect overall fibrinolytic activity and are highly dependent on the method of assay. The results provide important clues for detailed studies of the effects of haemodynamics on systemic haemostasis.

Novel seven coordination geometry of Sn(IV): crystal structures of phthalocyaninato bis(undecylcarboxylato)Sn(IV), its Si(IV) analogue, and phthalocyaninato bis(chloro)silicon(IV). The electrochemistry of the Si(IV) analogue and related compounds

Three newly elucidated crystal structures of group IV phthalocyaninato complexes are reported, along with data for two further SiPc carboxylate complexes. In one of these crystal structures, bis(undecylcarboxylate)Sn(IV) phthalocyanine, the tin ion is seven coordinate, which is a unique finding for this atom in phthalocyanine ring coordination. Comparison of these structures with other group IV phthalocyaninato and related structures reveals differences, illustrating features significant in the chemistries of Si(IV) and Sn(IV) ions. These differences are thought to originate from their differing sizes and polarizabilities. The structures show that the Sn(IV) ion can only occupy an in-plane location in the phthalocyaninato ring where it elongates toward the two axial ligands. When the axial ligands do not facilitate this elongation cis coordination is preferred and the Sn(IV) ion sits above the phthalocyaninato ring plane. In contrast, the Si(IV) structures, with smaller, harder (i.e., less polarizable) Si(IV) ions, are six coordinate with the Si(IV) ion in the phthalocyaninato ring plane in a distorted octahedral symmetry. The electronic spectra and cyclic voltammetry of some of the Si compounds indicate that on the electrode the oxidized/reduced species behave as though they are in a solid film, rather than a soluble freely diffusing species.

Influence of the number of days spent training in an abattoir with access to live cows on the efficiency of do-it-yourself artificial insemination

Data relating to 35,389 inseminations carried out in the first three years after inseminators were trained were collected by postal questionnaire from 94 do-it-yourself (DIY) artificial inseminators in the UK. The mean calving rate from 14,528 inseminations they carried out on 92 farms in the first year after they were trained was 59.4 per cent (range 5 to 92 per cent). In the second year the mean calving rate from 11,515 inseminations by 64 inseminators was 62.3 per cent (range 33 to 88 per cent), and in the third year the mean calving rate from 9346 inseminations by 49 inseminators was 64.6 per cent (range 41 to 92 per cent). There was an increase of 5.2 per cent in the mean calving rate over the three years with an overall mean calving rate of 61.5 per cent. Each trainee carried out an average of 376 inseminations (range 20 to 800) during the three years. Thirteen instructors were responsible for the tuition and the average time the trainees spent in an abattoir with access to live cows was 2.88 days, with a range from none to five days. For the trainees who spent up to three days training in an abattoir there was an increase of 5.9 per cent in the calving rate they achieved in their first year for every day they spent training with access to live cows (P < 0.005), but there were no significant effects on the outcome of their inseminations in their second or third years.

Norgestomet implants, plasma progesterone concentrations and embryo transfer pregnancy rates in cattle

A study was undertaken to test the hypothesis that supplementation with exogenous progestagen at the time of embryo transfer would enhance pregnancy rates in recipients. Two-hundred-and-seventy-two oestrus-synchronised crossbred heifer and cow recipients received 200 grade 1 and 72 grade 2 Simmental embryos transferred non-surgically. Heparinised blood samples were taken on day 6 and day 7 (oestrus = day 0) for the assessment of the endogenous plasma progesterone concentration. Half the recipients received an ear implant impregnated with 3 mg norgestomet on the day of embryo transfer. The pregnancy rates were 51.9 and 49.6 per cent for the norgestomet-treated and control groups, respectively. The pregnancy rate for grade 1 embryos was 56.0 per cent and for grade 2 embryos 36.1 per cent (P < 0.01). The breed of recipient, weekday of transfer, operator and condition score had no effect on pregnancy rate. The maiden heifers had a higher pregnancy rate (54.2 per cent) than the cows (46.2 per cent). The mean plasma progesterone concentrations of the pregnant and non-pregnant groups on day 6 were 6.7 ng/ml and 6.6 ng/ml, respectively, and 7.6 ng/ml in both groups on day 7.

Arthroscopic portals: the importance of blade selection

Arthroscopy of the knee is a commonly performed procedure with a low reported complication rate. We have experienced two cases during which no. 15 scalpel blades disengaged from the handle and remained within the joint. Although both the blades were successfully retrieved arthroscopically without injury to the knee, the procedures were prolonged, and there remained a potential risk of causing damage. We have subsequently altered our practice and now routinely use a no. 11 blade, with which we have had no complications. We discuss the importance of correct blade selection and surgical technique in avoiding this complication and present two illustrative case histories.

Management aspects of induced twinning in beef suckler cows using in vitro fertilised embryos

Twin and single pregnancies were induced in two groups of oestrus-synchronised beef cows by using a combination of artificial insemination and the transfer of in vitro fertilised (IVF) embryos. Single IVF embryos transferred non-surgically to the uterine horn contralateral to the corpus luteum of 43 previously inseminated cows resulted in a calving rate of 72 per cent with a twinning rate of 38.7 per cent. In 45 cows, two IVF embryos were transferred non-surgically to one uterine horn resulting in a calving rate of 51.1 per cent with a twinning rate of 39.1 per cent. The median gestation length for cows bearing twins was 10 days shorter than that of cows bearing single calves (P < 0.001). The proportions of cows that received assistance at calving were similar for twin and single births (57 per cent vs 45 per cent, P > 0.05), but the incidence of retained fetal membranes was much higher after the birth of twins (62 per cent vs 3 per cent, P < 0.001). Nineteen per cent of twin calves were stillborn compared with 6 per cent of single calves (P > 0.05). The median birthweight of the twin calves was 32 kg (68 per cent of the median weight of single calves). The nutrition of twin-bearing cows in late pregnancy was adequate when assessed in terms of their plasma glucose, non-esterified fatty acid and beta-hydroxybutyrate concentrations. Serum immunoglobulin concentrations were similar in single and twin calves suggesting that the passive transfer of antibody was not compromised in the twin calves.

Three-wavelength device for all-optical signal processing

We describe the operation of a semiconductor laser amplifier as a nonlinear element, using a novel three-wavelength configuration, which enhances the recovery rate of the nonlinear refractive index and permits choice of its sign and magnitude. Simple rate-equation analysis suggests that 100-GHz operation should be possible with powers of ~1 W.

ACTH (4-10) increases quantal content at the mouse neuromuscular junction

Adrenocorticotropic hormone 4-10 (ACTH 4-10), in concentrations of 50 nM and 1 microM, increased both the frequency of miniature endplate potentials and the amplitude of the endplate potentials in addition to decreasing the number of failures following stimulation of the phrenic nerve in the mouse in vitro. There was no effect of the peptide on either the amplitude of the miniature endplate potentials or the resting membrane potential of the muscle fibres. These results indicate that the action of ACTH 4-10 was to increase the quantal content of the endplate potential via a presynaptic action.

Development of an endocrine challenge test to investigate subfertility in ewes

Simultaneous or sequential injection of 250 ng gonadotrophin releasing hormone (GnRH) and 25 micrograms oestradiol benzoate, with luteinizing hormone (LH) measurements at 0, +20 min (after GnRH) and +16 h (after oestradiol), enabled investigation of the positive feedback effects on the hypothalamus and pituitary. Control ewes had pretreatment LH values of 3.1 +/- 1.2 ng/ml with an increment of 3.2 +/- 2.3 ng/ml 20 min after GnRH. Subfertile ewes, in spite of elevated pretreatment LH concentrations (15.8 +/- 9.5 ng/ml) in eight out of 10 ewes, had increments of 1.4-84 ng/ml after GnRH. Control ewes had LH increments of 3-75 ng/ml 16 h after oestradiol. Subfertile ewes with pretreatment LH concentrations less than 15 ng/ml also responded to oestradiol whereas those with initial LH concentrations 16-40 ng/ml had no further LH increment. Subsequent administration of 1000 iu pregnant mares' serum gonadotrophin (PMSG), with measurement of LH and oestradiol at 0, +24, +30, +48, +54, and +72 h, allowed assessment of ovarian response and hypothalamus-pituitary function. Five control ewes were sampled up to 30 h post-PMSG and only 1 had oestradiol concentrations greater than 10 pg/ml. Sampling up to 72 h in another five control ewes resulted in oestradiol concentrations greater than 10 pg/ml. Increments in LH concentration greater than 3 ng/ml were recorded in control and subfertile ewes with oestradiol concentrations greater than 10 pg/ml. The use of these endocrine challenge tests enabled positive diagnosis of abnormality on 8 out of 10 occasions.(ABSTRACT TRUNCATED AT 250 WORDS)

Practical uses of ultrasound in early pregnancy in cattle

Using a 'real-time' ultrasound scanner with a 3.5 MHz rectal transducer, a herd of 80 Friesian cows were scanned at weekly intervals during early pregnancy to assess the accuracy of pregnancy diagnosis, and the accuracy of twin detection. The growing fetuses were also measured to determine the relationship between crown-rump length and age. The accuracy of detection of pregnancy was inversely proportional to the age of the cow (r -0.967), the accuracy of detection of twinning was 100 per cent and there was strong correlation between fetal crown-rump length and age (r 0.98).

Specific transfer factor protects mice against lethal challenge with herpes simplex virus

Bovine transfer factor (TFd) specific to herpes simplex virus (HSV)1 or to HSV2 was prepared by immunizing calves with the corresponding virus. The TFd preparations were then injected into Swiss mice in an attempt to protect them against a subsequent lethal challenge with HSV1 or HSV2 virus. It was thus shown that injection of anti-HSV TFd protects the mice against the corresponding HSV virus, whereas the injection of a nonspecific TFd (anti-CMV) fails to protect against a challenge with HSV1. Furthermore, a dose-response effect was observed, since potent TFd preparations were ineffective when they were used at one-fifth of the original concentration. It seems, therefore, that animal models may be used to assay the potency of TFd preparations specific for herpes viruses.

Only B lymphocytes induce active enhancement of rat cardiac allografts

LEW rats were immunized 7 days before (LEW X BN)F1 heart transplantation with 10(7) BN donor cells, either purified erythrocytes (RBC), peripheral blood (PBL), splenic, nylon-wool-adherent (B-enriched) or nylon-wool-nonadherent (T-enriched) lymphocytes. Allograft rejection was only significantly enhanced in animals pretreated with lymphocyte populations containing surface immunoglobulin (SIgG)-positive cells (PBL, splenic, or B-enriched lymphocytes). Recipients immunized with RBC or T-enriched lymphocytes containing few, if any, SIgG-bearing B lymphocytes showed no significant graft prolongation.

The influence of carbohydrases on the growth of fungal pathogens in vitro and in vivo

Mixtures of mycolytic enzymes from various sources release protoplasts from living fungal tissue under suitable conditions. Such enzyme mixtures obtained from Coprinus comatus (mycolase I), Physarum polycephalum (mycolase II) and Lycoperdon pyriforme (mycolase III) are of low toxicity in mammals when given parenterally and are able to cure experimental systemic fungal infections in mice when administered alone or in conjunction with normally ineffective levels of conventional antimycotic drugs such as amphotericin B. The effect is believed to be due to enzymic degradation of the fungal cell wall either killing the fungus directly or enhancing activity of existing antifungal agents by increasing access to the cell interior.

Cross-reactivity with mouse antigens in the ferritin immunogenetic (IR-gene) system

Structural similarity between antigens and self molecules could be responsible for low antibody responses in different immunogenetic (IR-gene) systems. B10.M and B10.D2 strains are high responders, whilst A. Thy-1-1 mice are low responders, following primary immunization with ferritin in saline. Cross-reactivity between mouse-self antigens and ferritin was tested by antigen excess and radioimmunoassay techniques, using cells obtained from normal, unimmunized high- and low-responder mice, to compete for specific antibody. Low-responder A.Thy-1-1 mouse cells consistently displaced more anti-ferritin antibodies than did high-responder B10.M and B10.D2 mouse cells at varying antibody and cell concentrations and these differences were statistically significant (P less than 0.001). It is suggested that the responder status of different strains of mice, following primary immunization with ferritin in saline, could be explained by the degree of cross-activity between self determinants and antigen, such that low responders cross-react to a greater degree with the test antigen than do high-responder mice. A similar mechanism of cross-reactivity could operate in the pathogenesis of HLA-linked diseases.

Genetic control of the immune response to ferritin in F1 hybrid mice

The immune response to the antigen horse spleen ferritin, has been investigated in ten inbred parental strains and seven different F1 hybrid strains of mice, using an antigen excess technique. The degree of dominance in an F1 hybrid system can be estimated by using the Fisher dominance index. The responses in F1 hybrid animals, obtained from crosses of high and low responder parents, varied from dominant to recessive but the overall mean dominance index for the ferritin immunogenetic system was found to be -0.0467 +/- 0.0083 (mean +/- s.e.), a value close to zero, which suggests a codominant mode of inheritance of IR-genes to ferritin and this is consistent with most published data in other F1 IR-gene systems.

The effects of erythrocyte-absorbed H-2 alloantisera on mixed lymphocyte culture reactions

One-way mixed lymphocyte culture reactions were inhibited by the addition of H-2 alloantisera directed against the stimulator cell type. The sera retained their original inhibitory activity after the removal from them of conventional H-2K antibodies by exhaustive absorption with erythrocytes. The absorbed antisera had specificity for Ia but not H-2 antigens thereby indicating that the inhibitory activity of the sera is a function of antibodies against I region products. H-2 and Ia alloantisera directed against the responder cell type did not specifically inhibit culture reactions: they either had no effect or they apparently increased stimulation. This increase appeared to be immunologically specific, at least in part, and to require some heat-labile normal serum component for its elicitation. It is concluded that treatment of responder cells inactivates or destroys some normally inactive or inhibitory subpopulation such that the remaining cells respond better to allogeneic stimulation. Both the anti-stimulator and the anti-responder effects were seen with either whole serum or crude immunoglobulin preparations when one of these was added to the culture or used for pretreating cells before establishing the culture.

Genetic control of the immune response to ferritin in mice

The immune response to the antigen horse spleen ferritin was tested in sixteen inbred strains of mice. Using a fixed antigen percentage bound isotope technique, it was found that the quantity of antibody produced was related to the genetic status of the responding animal. A continuous distribution of responses was obtained, which were found to be linked to H-2 loci and the 2 non-H-2 loci 'Tla' and 'Theta' and these responses are detectable following primary immunization. It is suggested that the continuous distribution of quantitative antibody responses to ferritin, is compatible either with a large number of IR-genes or with a cross tolerance hypothesis requiring no IR-genes at all.

The detection of Ia antibodies in polyspecific H-2 alloantisera absorbed with erythrocytes

H-2 alloantisera contain Ia antibodies whose detection is obscured by the presence of serodominant K,D specificities. A method is described whereby Ia antisera can be prepared by absorbing conventional H-2 sera with donor-strain erythrocytes. The analysis of such absorbed antisera has led to the identification of the new specificity Ia.16, and the redefinition of the specificities H-2.34 and H-2.46 as complex Ia specificities which map in the I-A region of the H-2 complex. A number of other so-called H-2 specificities also appear to have Ia-like properties.

The dominant role of Ia antibodies in the passive enhancement of H-2 incompatible skin grafts

The ability of H-2 antisera and their constituent K and Ia antibodies to enhance the survival of skin allografts was investigated. Ia sera were prepared from H-2 alloantisera by exhaustive absorption with donor-strain RBC and the absorbed K antibodies were also recovered by acid elution of the RBC. The removal of conventional K/D antibody in no way diminished the activity of enhancing sera over wide dose ranges in two different incompatibility systems. The recovered K/D antibodies in the doses used had at best a trivial enhancing effect. The dominant role of Ia antibodies in enhancement was confirmed by showing significant prolongation of graft survival in third-party systems where the sera covered only some of the Ia antigens in incompatibilities involving K,D and Ia differences and in homologous systems using Ia sera fractionated into their constituent mono-specificities. It is concluded that enhancement is a function of antibodies directed against Ia antigens (I region products) and that antibody against conventional histocompatibility antigens such as H-2.K, D, and by homology HL-A and Ag-B has only a minor role in passive enhancement.

In vitro cytotoxicity of anti-theta (Thy-1) antibodies combined with chlorambucil

Two methods are described for linking chlorambucil to antibodies. At low pH an association is formed which is not stable under physiological conditions and the cytotoxicity is the result of the independent action of chlorambucil and antibody. At pH 8 a more stable linkage is formed and this complex shows specific toxicity for cells carrying the appropriate antigen. Uncombined chlorambucil and antibody are more cytotoxic that chlorambucil alone, especially if the cells are exposed first to the chlorambucil.

Protection of mice against syngeneic lymphomata: II. Collaboration between drugs and antibodies

Rabbit anti-mouse tumour cell serum can be made tumour specific by absorption with normal mouse cells and in an in vivo protection test can be shown to have a measurable protective effect on mice against a given number of lethal doses of a lymphoma. Some drugs have been evaluated in this system. When drug treatment is combined with antibody treatment much greater protection can be obtained than when the same amounts of drug or antibody are used alone. It is preferable to administer drug before antibody and with the combined schedule it is possible in the test model to protect all mice from tumour growth, even allowing the tumour up to 48 h "get-away" time before starting treatment.

Protection of mice against syngeneic lymphomata: I. Use of antibodies

Protection tests using passively administered antibody have been carried out using 2 mouse lymphomata. The classic model ("Gorer System") used alloantiserum which was absorbed in vivo to make it tumour specific before use. In order to provide a system suitable for our work, the model was changed by stepwise transitions to tumour specific immunoglobulin made from xenoantiserum absorbed in vitro, since such a procedure is also applicable to human patients. The time lapse used between challenge and treatment in the allo-system was generally ± 2 h but in the xeno-system could be extended to + 18 h. The xenoantisera could not be absorbed in vivo but required 3 to 5 × 10(3) spleens per 100 ml serum to absorb in vitro to render them tumour specific. The protective antibody was in the IgG (not IgM) fraction of serum. Maximal tumour specific antibody (measured by in vivo protection) appeared after the third injection of rabbits for one lymphoma, but after the fifth for another. The sera were not cross-reactive among 3 lymphomata tested, of which 2 were of the same H-2 genotype.

In vivo and in vitro effects of tumour specific antibodies with chlorambucil

Allo- and xenoantisera have been prepared against mouse tumours, and xenoantisera against human tumours, and absorbed to remove all antibodies against normal host lymphocytes as judged by cytotoxicity tests. The sera were fractionated and the Ig shown to be cytotoxic (complement mediated) for the appropriate tumour cells in vitro in the case of some mouse anti-mouse and rabbit anti-mouse, and specifically fluorescent in the case of goat anti-human tumour cells. In mouse model systems using lymphomata, these Ig preparations gave tumour specific protection. The protective effect of chlorambucil was also assessed in these models. Chlorambucil was linked to antibody and using the mouse theta system in vitro it could be seen that both antibody specificity and drug activity were retained in the complexes. Such drugged tumour specific antibodies were tested in vivo to find if the antibodies would carry the drug to the tumour target and destroy it, or so affect the immune balance as to change it in favour of the host. Favourable effects were found but these could not be attributed to “homing”. Protection against tumour death in the mouse lymphoma models was much better using complexes than could be achieved with either antibody or drug alone, but no better than the same amounts of antibody and drug injected unattached. Thus true homing has been shown in vitro but has not been achieved in vivo, though an additive or possibly a synergistic effect of antibody and drug has been demonstrated. It is likely that antibody destroys drug affected cells rather than the reverse.