A behavioral comparison of the common laboratory rat strains Lister Hooded, Lewis, Fischer 344 and Wistar in an automated homecage system.

Behavioral characterization is an important part of establishing novel animal models, but classical behavioral tests struggle to reveal conclusive results due to problems with both reproducibility and validity. On the contrary, automated homecage observations are believed to produce robust outcomes that relate more to natural animal behavior. However, information on the behavior of background strains from such observations, which could provide important reference material, is rare. For this reason, we compared the behavior of the commonly used Lister Hooded, Lewis, Fischer 344 and Wistar rats during 70 h of exposure to an automated homecage system at 2, 4 and 6 months of age. We found considerable strain differences in metabolic parameters, novelty-induced and baseline activity-related behavior as well as differences in the development of these parameters with age. The results are discussed in terms of advantages and disadvantages of the system compared to classical behavioral tests, as well as the system's ability to recreate common findings in literature.

Keep cool: memory is retained during hibernation in Alpine marmots.

Hibernators display severe changes in brain structure during deep torpor, including alterations in synaptic constitution. To address a possible effect on long-term memory, we examined learning behavior and memory of the hibernator Marmota marmota. In two operant conditioning tasks, the marmots learned to jump on two boxes or to walk through a tube. The animals were trained during their active season. Performance improved during the training phase and remained stable in a last test, four weeks before entrance into hibernation. When retested after six months of hibernation, skills were found to be unimpaired (box: before hibernation: 258.2+/-17.7 s, after hibernation: 275.0+/-19.8 s; tube: before hibernation: 158.4+/-9.0 s, after hibernation: 137.7+/-6.3 s). Contrary to these findings, memory seemed to be less fixed during the active season, since changes in test procedure resulted in impaired test performance. Besides the operant conditioning, we investigated the animals' habituation to a novel environment by repeated open field exposure. In the first run, animals showed exploratory behavior and thus a high locomotor activity was observed (63.6+/-10.7 crossed squares). Upon a second exposure, all animals immediately moved into one corner and locomotion ceased (7.2+/-1.9 crossed squares). This habituation was not altered even after hibernation (6.1+/-1.1 crossed squares). We thus conclude that long-term memory is unaffected by hibernation in Alpine marmots.

The role of the rheumatologist in managing arthritis.

When and why should a patient with arthritis see a rheumatologist? To establish or confirm the diagnosis: aim for diagnosis within six weeks of onset. To plan an optimal management program: early, aggressive treatment is essential to achieve the best outcome in patients with inflammatory arthritis. To assess the response to treatment: failure to respond to treatment requires a change in drug regimen--objective measures of disease activity should be used.

Pharmacokinetics and biological actions of subcutaneously administered human brain natriuretic peptide.

Human brain natriuretic peptide (hBNP) has demonstrated favorable hemodynamic effects in patients with congestive heart failure; however, the peptidic nature of this compound has focused clinical testing on protocols involving intravenous delivery. We have studied subcutaneous delivery as an alternative method of administering hBNP. Administration of 30 microgram/kg hBNP by either subcutaneous or intravenous delivery protocols resulted in significant hBNP-immunoreactive material in the plasma with area under the plasma concentration-time curve values of 310 +/- 20 nmolxmins/liter and 187 +/- 47 nmolxmins/liter, respectively. Plasma cyclic GMP, a surrogate marker of activation of the biological receptor for hBNP, was elevated for a longer period of time following subcutaneous delivery compared with intravenous delivery. Subcutaneous delivery of 30 microg/kg hBNP resulted in natriuresis, diuresis and reduced systolic blood pressure in anesthetized normotensive rabbits, effects similar in magnitude yet prolonged in duration compared with those elicited by the same dose of hBNP delivered intravenously. Systolic blood pressure following hBNP treatment remained below base-line values for 50 and 150 min following intravenous and subcutaneous delivery protocols, respectively. These results suggests that subcutaneous delivery of hBNP may be a viable therapeutic alternative to intravenous modes of delivery.

Human brain natriuretic peptide reduces blood pressure in normotensive and acute norepinephrine-induced hypertensive rabbits.

Human brain natriuretic peptide (hBNP) is a cardiac-derived peptide hormone with potent hemodynamic and renal effects in dogs, monkeys, and humans, but not in rats. At present there is no small animal model to study the actions of hBNP. These studies describe the effects of hBNP in New Zealand White rabbits in normotensive and acute norepinephrine-induced hypertensive states. Intravenous administration of hBNP (1, 3, 10, and 30 microg/kg) to anesthetized rabbits resulted in a dose-dependent diuresis and natriuresis and a decrease in systolic blood pressure. Bolus administration of hBNP resulted in a time- and dose-dependent accumulation of plasma cyclic GMP, consistent with activation of a particulate guanylyl cyclase receptor. The hemodynamic actions of hBNP suggest clinical utility for the management of acute hypertension associated with numerous surgical procedures, a condition linked to catecholamine activation. In rabbits with norepinephrine-induced acute hypertension, bolus and continuous infusion of hBNP markedly reduced blood pressure. These studies demonstrate that the rabbit is a useful species to study the hemodynamic and renal effects of hBNP and that this peptide may have therapeutic utility for the acute reduction of hypertension associated with catecholamine activation.

Demonstration of local immunosuppression with methylprednisolone in the sponge matrix allograft model.

This study evaluated the effect of locally delivered methylprednisolone on the systemic and local immune response in the sponge matrix allograft model. Polyurethane sponges were coated with peritoneal exudate cells from DBA/2 (H-2d) or C57Bl/6 mice (H-2b) and placed subcutaneously in C57BL/6 recipients 24 hr later. Each mouse received both a syngeneic and an allogeneic sponge graft. Local immunosuppression was effected by placement on day 0 of cellulose/matrix pellets containing a preparation of increasing quantity of controlled release MP or by daily intrasponge injection of MP. Local immunosuppression was demonstrated by decreased cytotoxicity on day 12 in the allogeneic sponge receiving MP directly, as compared with the groups that received MP in the opposite syngeneic sponge or no MP. This effect was noted at a specific MP dose (0.5 mg/kg/day). Absolute numbers of precursor cytolytic cells and mature cytolytic cells (determined by limiting dilution analyses) infiltrating the allografts were also decreased in the sponges receiving MP directly, relative to the groups receiving MP in the opposite syngeneic sponge. Maintenance of systemic (in contrast to local) immunity was also demonstrated. Animals treated with local MP into a simultaneously placed syngeneic sponge or in whom no MP was delivered became sensitized to a synchronous DBA/2 sponge and rejected a subsequent DBA/2 skin graft in second-set fashion. Conversely, animals that received local MP into their synchronous DBA/2 sponge rejected a subsequent DBA/2 skin graft or a third-party graft with first-set kinetics. The presence of local MP at the initial graft site prevented the animals from becoming sensitized to the presented alloantigen but did not keep the animal from developing a rejection response to a third-party skin graft with first-set kinetics. It appears that delivery of MP locally to the site of antigen is an effective method to modulate alloreactivity. In addition, the sponge matrix allograft appears to be a useful model for studying local immunosuppression.

The 'shrinking lungs syndrome'--an infrequently recognised feature of systemic lupus erythematosus.

Two cases of the 'Shrinking Lungs Syndrome' in patients with systemic lupus erythematosus are described to highlight an infrequently recognised feature of this condition. Respiratory muscle weakness, improved by steroid therapy, was demonstrated in each patient and considered to be the mechanism underlying the respiratory symptoms.

Schistosoma mansoni: effect of transferrin and growth factors on development of schistosomula in vitro.

We have studied the role of human transferrin and of exogenous iron on early growth and development of schistosomula of Schistosoma mansoni in vitro, as determined by developmental achievement and thymidine incorporation. To help define an adequate serumless medium we also utilized fibroblast growth factor, platelet-derived growth factor, epidermal growth factor, and multiplication-stimulating activity, all present in the hepatic environment of developing schistosomula, as well as certain commercial serum substitutes. Supplementation of basal medium with transferrin in the range of 250-1,000 micrograms/ml provided development equal or superior to serum-supplemented medium, at least within the first 2 wk of culture. Serum-free medium supplemented with Nutridoma-HU or -SP stimulated development to a lesser extent. The stimulatory effect of iron (as ferric sulfate) on thymidine incorporation was removed by deferroxamine, a chelating agent. Competitive inhibition studies with 125I-labeled and unlabeled transferrin indicated the presence of nonsaturable binding sites on schistosomula.

Schistosoma mansoni: insulin independence.

Several authors have reported that schistosomes are affected by host hormones, including insulin. We found that insulin in a 10,000-fold range of concentrations failed to affect glucose consumption of males, females, or pairs of Schistosoma mansoni incubated for periods up to 24 hr. Insulin, vasopressin, or tetradecanoyl phorbol acetate (an insulin mimic) did not affect the uptake and incorporation of [14C]glucose and [14C]deoxyglucose over the active transport range. Competitive binding studies using 125I-insulin and 125I-insulin-like growth factor II, with varying concentrations of unlabeled hormones, demonstrated only nonspecific binding to intact worms or subcellular fractions. This generalized nonspecific uptake of label was also shown by autoradiography, suggesting that specific insulin receptors are absent from S. mansoni. We conclude that plasma glucose levels are sufficient to supply the metabolic requirements of schistosomes by diffusion, and that no insulin-dependent mechanisms have evolved in these parasites.

Schistosoma mansoni: reversible destruction of testes by procarbazine.

1. The anticancer drug procarbazine is profoundly damaging to the testes of Schistosoma mansoni when administered at 200 mg/kg or more to the mouse host. Somatic tissues appear entirely unaffected. 2. Within 2 days the meiotic process is disrupted, and primary and secondary spermatocytes and spermatids are destroyed and replaced by amorphous granular material. 3. The testes regenerate within about 15 days, apparently from surviving spermatogonial resting cells near the germinal epithelium of the testis. 4. Livers of mice treated once 7 weeks earlier have numerous egg granulomas and give rise to many miracidia, suggesting that full testis function is regained. 5. Male worms given the drug at 200 mg/kg at 19 days of age and fixed 7 weeks later have on average one testis less than control worms, indicating that about 15% of immature testes are unable to regenerate, whereas mature worms given the drug regenerate the normal number of testes. 6. The drug did not have significant antispermatogenic effects when male worms were incubated for a week with various concentrations in vitro, suggesting that a host metabolite is the active agent.

Lower limb amputation secondary to large vessel involvement in scleroderma.

A 34-year-old woman with scleroderma was admitted to hospital with pain and weakness of her left foot. She was subsequently shown to have developed a popliteal artery occlusion associated with progressive lower limb ischaemia. This culminated in below-knee amputation. Marked intimal hyperplasia of the large vessels in the leg was noted histologically. An increasing number of cases of large vessel involvement in scleroderma, a disease that primarily affects the microvasculature, has been reported. Scleroderma should be regarded as a rare cause of large vessel peripheral vascular disease.

A crossover study of naproxen, diclofenac and tolmetin in seronegative juvenile chronic arthritis.

Nonsteroidal anti-inflammatory drugs (NSAID) are useful in the management of juvenile chronic arthritis (JCA) and efficacy has usually been compared with aspirin. The disadvantages of aspirin include the frequency of dosage, monitoring of salicylate levels and concern about Reye's syndrome. We have performed a single blind crossover study comparing naproxen 10 mg/kg/day, tolmetin 25 mg/kg/day and diclofenac 2 mg/kg/day in 28 children with seronegative JCA over 12 weeks. Clinical and laboratory assessments were made after 4 weeks of treatment on each drug. Clinical improvement was seen with all three NSAID compared to baseline after a 24-hour washout period, but statistical significance was reached in only 2 or 3 of the clinical parameters for each drug. Side effects were mild and typical of NSAID, but occurred less frequently with naproxen (5) and tolmetin (5) than with diclofenac (7). Thus the anti-inflammatory effect of all three drugs was confirmed with no significant differences between them in terms of efficacy and tolerance. Tolmetin 200 mg tablets are now only available in France and N. America, therefore naproxen or diclofenac are recommended as the first line of treatment in children with chronic arthritis over the age of 5.

Sibling pairs affected by chronic arthritis of childhood: evidence for a genetic predisposition.

Twelve families with a sibling pair affected by seronegative juvenile chronic arthritis (JCA) were studied. The ratio of HLA haplotype sharing was significantly different from that expected. No common haplotype was found. All 10 sibling pairs concordant for pauciarticular disease shared 2 haplotypes and the other 2 pairs shared one haplotype. These findings are evidence of a genetic predisposition to develop pauciarticular onset JCA in the families studied and suggest the presence of a disease susceptibility gene or genes within the major histocompatability complex.

A comparison of low dose levamisole and penicillamine in rheumatoid arthritis.

Levamisole (150 mg once weekly) was compared with penicillamine (250 mg daily) in a single blind independent observer study in 28 patients with rheumatoid arthritis over twelve months. Fifty percent (8/16) of patients stopped levamisole, five within three months of starting, while only two of twelve stopped penicillamine. In those patients able to tolerate treatment for twelve months, both regimens produced a significant and comparable reduction in disease activity, with the onset of action of penicillamine occurring at three months compared with six to nine months for levamisole. Radiological progression of disease occurred in both groups. Levamisole in low dose may improve parameters of disease activity in rheumatoid arthritis but poor patient tolerance, slow onset of action and failure to prevent radiological progression limit its usefulness.

HLA studies in IgM rheumatoid-factor-positive arthritis of childhood.

The clinical course of children with IgM rheumatoid-factor-positive chronic arthritis closely resembles that of seropositive rheumatoid disease in adults. The frequency of HLA DR4 is known to be increased in adults with seropositive rheumatoid arthritis, but the first major report on childhood arthritis did not suggest a correlation, though only 8 seropositive cases were included. Fifty-two children with polyarthritis beginning before the age of 16 who persistently carried IgM rheumatoid factor were studied. HLA DR4 was present in 60% of these children but was found in only 29% of 93 patients with seronegative juvenile arthritis and 27% of a normal adult population. These results suggest immunogenetic similarities in patients with seropositive arthritis irrespective of age of onset.

Immunologic regulation in pregnancy.

Theories to explain the failure of rejection of the fetus by the mother during pregnancy include immunologic privilege of the uterus as a graft site, lack of transplantation antigen expression on the trophoblast, weakening of maternal cellular immunity during pregnancy, and separation of maternal and fetal circulations. Evidence for and against each of these theories is discussed. Local concentration of a variety of hormones, including human chorionic gonadotropin (HCG), sex steroids, alpha-fetoprotein, and immunoglobulins, could provide a blocking mechanism to prevent maternal cellular immune attack. Possibly, progesterone, antibodies, and immune complexes are important in protecting the placenta and ultimately the fetus from rejection. Elucidation of regulatory mechanisms in pregnancy may be applicable to other problems in immunology.

Analysis of the radioimmunoassay for gonadotropin-releasing hormone (GnRH): studies on the effect of radioiodinated GnRH.

When GnRH is radioiodinated by the chloramine-T method, two immunoreactive labeled species are formed at pH 6.5 with a chloramine-T: GnRH molar ratio of 11:1, whereas four bands (I, IIa, IIb, and III) are separated by polyacrylamide gel electrophoresis when the hormone is iodinated at pH 7.5 in a system containing a 97:1 molar ratio of chloramine-T:GnRH. Because they were more stable and were more immunoreactive than the other products, band I and band IIa from the latter system were used separately as tracers with Niswender antiserum R-42 in radioimmunoassays for GnRH. The standard curves of each tracer are distinct: when analyzed after log-logit transformation, the band I curve had a mean slope of -3.31 +/- 0.2 (SE) and a 50% B/Bt level of 9 +/- 0.8 pg (n=8) of synthetic GnRH, whereas the band IIa standard curve had a slope of -2.30 +/- 0.6 and a 50% B/Bt value of 20 +/- 0.9 pg (n=11). The sensitivity of both assays is approximately 2.0 pg. Gn RH concentrations in plasma and serum samples assayed with band I were consistently greater than those assayed with band IIa. Normal adult male plasmas assayed with band I measured 21 +/- 0.9 pg/ml, whereas band IIa values were 8 +/- 0.4 pg/ml. No difference between plasma and serum was detected, nor was there any difference among adult men, adult women, prepubertal children, hypogonadal patients, or hypopituitary patients with either assay. Plasma GnRH concentrations were also similar in jugular and vena cava samples from intact and castrated male rats. Because many of the samples were at or below the sensitivity of the band IIa assay, they were concentrated after extraction with either methanol or acid-ethanol. However, endogenous immunoreactive GnRH could not be concentrated by these extraction procedures. As measured in the band IIa assay, hypothalamic extracts from control adult male rats contained 3.1 +/- 0.4 ng while hypothalami from castrated rats contained 1.4 +/- 0.1 ng. Similar but slightly lower values were obtained with band I. In contrast, the GnRH content of pineal glands from intact and castrated male rats was similar (approximately 150 pg) when determined in either assay. These studies emphasize that: 1) the characteristics of the radioiodinated hormone can influence the quantitation of GnRH; and 2) endogenous plasma concentrations of GnRH are much lower than previously reported.