Vaccine evaluation studies of replication-defective SIVsmB7

Non-infectious virus-like particles of SIVsmB7 that expresses env and gag gene products but are defective in pol and vpx/vpr were assessed for their ability to induce protective immunity against infection with pathogenic SIVsmE660 in rhesus macaques. Animals were immunized in three groups: group A was primed with cell-associated SIVsmB7 and boosted with cell-free SIVsmB7; group B was primed with cell-free SIVsmB7 and boosted with cell-free SIVsmB7 conjugated to iron oxide microbeads; group C was primed with cell-free SIVsmB7 mixed with Titer Max adjuvant and boosted with cell-free SIVsmB7 mixed with SAF-M adjuvant followed by secondary boosting with cell-free SIVsmB7 conjugated to microbeads. Animals were challenged intravenously with 20 animal infectious doses of SIVsmE660 grown in rhesus peripheral blood mononuclear cells 3 weeks after final boosting. All animals became infected as evidenced by quantitative virus cultivation. Sera from immunized animals contained low-titer antibodies by ELISA and low or undetectable neutralizing antibodies on the day of challenge but strong anamnestic antibody responses were observed following challenge. Interestingly, 2 of 3 animals in group A showed evidence of transient viremia and more stable CD4 counts following challenge as compared to the other immunized animals and to non-immunized controls. Thus, immunization with cell-associated SIVsmB7 did not provide sterilizing immunity against challenge with a highly pathogenic SIV strain but might have caused virus clearance later in infection.

Ovarian torsion associated with granulosa-theca cell tumor in a mare

A 12-year-old Morgan mare was examined because of stallion-like behavior of 45 days' duration. Palpation per rectum and transrectal ultrasonographic examination revealed a large left ovary with multiple cystic areas and crepitus. A granulosa-theca cell tumor was suspected. During hospitalization for further evaluation of the affected ovary, the mare developed signs of abdominal pain. Exploratory surgery revealed a large left ovary, which was black with a necrotic and friable surface, and a 720 degrees clock-wise torsion of the ovarian pedicle. Torsion was corrected, and oophorectomy was performed. The mare recovered satisfactorily from surgery. Histologic diagnosis was granulosatheca cell tumor with marked diffuse necrosis. To our knowledge, torsion of the ovarian pedicle has not been reported in the veterinary literature. However, it is not uncommon in women. Ovarian torsion seems to develop in association with neoplasia, cysts, and ovarian hyperstimulation syndrome. Ovarian torsion should be considered as a differential diagnosis for mares with a known ovarian pathologic change such as neoplasia or abscess if signs of abdominal pain are evident.

A study of HIV seroprevalence in a group of homeless youth in Hollywood, California

The objective of this descriptive-exploratory study was to examine the HIV seroprevalence rate among a sample of homeless youth in Hollywood, California. A total of 96 respondents (age 14-24) were administered a questionnaire and had their blood drawn to test for the presence of HIV antibodies, during nightly street outreach activities conducted by Covenant House California. The HIV seroprevalence rate was 11.5% for the sample. Chi-square analysis showed strong correlation between HIV status and sexual risk behavior but not for HIV status and drug-related risk behavior.

Fecundity of naturally bloodfed Culiseta melanura

Naturally bloodfed Culiseta melanura were collected annually from resting boxes in and around a swamp in Oswego County, NY from 1982 to 1989. Females were held individually in a laboratory until they oviposited. Except in 1982, every other female was provided a 10% dextrose solution. Females were classed as alive or dead following oviposition and female size was based on abdomen length, measured after oviposition. Egg rafts from each female were held individually and the numbers of larvae and unhatched eggs were counted. Fecundity (number of eggs laid per female) was based on number of larvae plus unhatched eggs. Rafts from 2,120 females averaged 129 eggs and 106 larvae per raft. Rafts from females that were alive following oviposition were significantly larger and produced more larvae than those of females that died following oviposition. Availability of sugar influenced female survival but not egg raft production. Size and fecundity of females decreased from May through September. These differences were attributed to the temperature and larval density of breeding crypts. Seasonal changes in size may influence the vector efficiency of Cs. melanura.

An apoptotic endonuclease activated either by decreasing pH or by increasing calcium

DNA fragmentation in isolated nuclei from the murine IL3-dependent bone marrow cell line BAF3 could be stimulated either by decreasing pH below 6.5 or by adding microM calcium at neutral pH. An endonuclease which could also be stimulated either by a decrease in pH, to 6.5, or by the presence of microM calcium at neutral pH, was purified 10(4)-fold from nuclei of BAF3 cells. Digestion of DNA with the purified enzyme resulted in 5′-terminal hydroxyl and 3′-terminal phosphate ends. These characteristics are distinct from those described for other mammalian endonucleases. The possible role of this enzyme in genome digestion during apoptosis is discussed.

The effect of interferon-alpha on the pituitary-adrenal axis

This report concerns the use of a minimum stress animal model for evaluating the neuromodulatory effects of interferon-alpha (IFN-alpha). Male Sprague-Dawley rats, 350-450 g, received jugular catheters and were habituated to handling and sampling arenas. These procedures will minimize stress usually associated with i.v. injections and blood sampling. Natural rat IFN-alpha/beta (RaIFN-alpha/beta) endotoxin free (Lee Biomolecular Research Laboratories, San Diego, CA) or recombinant human IFN-alpha, (rHuIFN-alpha) (a gift from Hoffman La Roche, Nutley, NJ) was injected into rats via catheter at various IFN concentrations. Controls were injected with either (1) vehicle (saline), (2) human or bovine serum albumin in saline, or (3) heat-denatured RaIFN-alpha/beta. Experiments were begun (0 h) at about 0900 h, and blood samples were withdrawn at intervals up to 2 h after IFN or control injections and replaced by the same volume of saline. The concentrations of corticosterone and ACTH in peripheral plasma were measured by radioimmunoassay. Both IFN, when injected at concentrations of 300 or 600 U/g body weight (U/gbw), stimulated an increase above 0 h levels of both hormones in the same animals. Additionally, the stimulation was also evident when compared with plasma hormone levels in animals injected with control substance in a parallel time course. After administration of 150 U/gbw of either IFN, only the increase in the blood corticosterone was significant. These studies demonstrate that both homospecific (RaIFN-alpha/beta) and heterospecific (rHuIFN-alpha) IFN preparations are capable of stimulating the pituitary-adrenal axis.

Outcome of grafts with long-lasting delayed function after renal transplantation

To assess the impact of long-lasting acute renal failure after renal transplantation on late graft prognosis, we compared the risk factors and outcome in renal allografts with delayed function for >3 weeks after renal transplantation (long-lasting delayed graft function [LLDGF]) (group A, n=64), and in four control groups: group B, initially functioning grafts (n=322); group C, grafts with delayed function for <2 weeks after transplantation (n=110); group D, grafts with delayed function for 14 to 20 days after transplantation (n=57); and group E, never-functioning grafts (n=88). Donor asystolia or instability, stroke as a cause of donor's death, and prolonged cold ischemia and vascular surgical times were some predictors of LLDGF. Overlap was important, but 43% of patients of group A, 15% of group B, 25% of group C, 31% of group D, and 40% of group E (P<0.01) presented two or more risk factors for severe acute tubular necrosis after transplantation. Acute rejection and early complications were very frequent in group A. Also, patient survival was significantly decreased in group A, due to a higher incidence of infectious mortality. Graft survival was moderately (NS) decreased in group A. Serum creatinine was initially higher in patients of group A, but differences disappeared after the second year. However, late proteinuria was more frequent in group A, and there was also a trend for a higher prevalence of hypertension in this group. LLDGF cannot be reliably predicted at the time of renal transplantation. The main consequence of LLDGF is an excess mortality, while the impact on late graft function is less significant. Short-lasting delayed graft function does not seem to have a negative impact on the outcome of renal transplantation.

Evaluation of shelf arthroplasty as a treatment for hip dysplasia in dogs

OBJECTIVE

To evaluate effects of shelf arthroplasty on coxofemoral joint laxity and progression of degenerative joint disease in young dogs with hip dysplasia.

DESIGN

Prospective, controlled study.

ANIMALS

10 dogs between 10 and 24 months old and weighing between 20 and 27 kg. All dogs had bilateral coxofemoral joint laxity (i.e., an Ortolani's sign).

PROCEDURE

In all dogs, shelf arthroplasty was performed on the right coxofemoral joints, and a sham procedure was performed on the left. Dogs were evaluated before and after surgery by means of lameness assessment, coxofemoral joint palpation and goniometry, thigh circumference measurement, and radiography.

RESULTS

There were no significant changes in coxofemoral joint mobility, range of motion, joint laxity, degree of degenerative joint disease, or thigh circumference during the study. A greater amount of periacetabular bone formed on the right side than on the left side; however, dogs did not develop large bony shelves, and the amount of periarticular bone decreased over time. The polymer implants remained in their original position and were encapsulated by fibrous tissue. There was no histologic evidence of osteoconduction by the implants.

CLINICAL IMPLICATIONS

The polymer implants used in this procedure do not appear to be osteoconductive. Shelf arthroplasty was associated with minimal morbidity and was not associated with serious adverse sequelae in this study, but the procedure did not alter the progression of hip dysplasia in these dogs. We cannot advocate shelf arthroplasty using this polymer as a treatment for dogs with hip dysplasia.

Evidence for multiple foci of eastern equine encephalitis virus (Togaviridae:Alphavirus) in central New York State

A regional surveillance system for eastern equine encephalitis (EEE) virus was established in central New York in 1984 after the 2nd human EEE fatality occurred in 1983. Extensive mosquito surveillance activities were coordinated with the rapid laboratory processing of mosquito specimens for EEE virus. Active surveillance for EEE infections in humans and equines also was initiated. Results of long-term surveillance detected the presence of multiple Culiseta breeding swamps. A 6-yr interepizootic period (1984-1989) was followed by 2 yr of equine EEE. In 1990, there were 7 equine cases and a record number of EEE virus isolations from mosquitoes (n = 86), wild birds (n = 27), and sentinel pheasants (n = 7). In 1991, 7 equine cases also occurred, although there were fewer isolations from mosquitoes (n = 40). The sequence to the appearance of EEE virus at swamps and upland sites and at individual swam complexes, and the spatial and temporal distribution of equine cases provide evidence for multiple foci of EEE virus in central New York. The role of infected Culiseta melanura (Coquillett) in the transfer of EEE virus between swamp and upland areas and among swamp complexes is advanced.

Power spectral analysis of heart-rate variability reflects the level of cardiac autonomic activity in rabbits

Power spectral analysis of heart rate (HR) variability was tested in conscious rabbits to assess the reliability of this method for assessing cardiac autonomic function in normal rabbits under resting conditions. Evaluation of power spectrum was performed in 5 rabbits under normal resting conditions and after sympathetic, parasympathetic and combined sympathetic plus parasympathetic blockade. Rabbits were randomly assigned to undergo sympathetic (propranolol) or parasympathetic (methscopolamine) blockade at the initial step followed by combined blockade. The power spectrum of heart-rate variability in rabbits was presented as one broad spectral component at frequencies mainly between 0 and 0.5 Hz. This component was considerably modulated by both sympathetic and parasympathetic influences with substantial overlap of sympathetic- and parasympathetic-related components of the spectrogram. Nevertheless, it was clearly shown that power of heart-rate variability at frequencies from 0.4373 Hz to 0.5625 Hz was determined only by parasympathetic influences, and sympathetic modulation of HR was presented mainly at frequencies from 0.0625 Hz to 0.1875 Hz. Spectral subcomponent analysis of the power spectrum of HR variability may be useful to follow changes in cardiac autonomic function in rabbits.

The respiratory effects of reduction of mite allergen in the bedrooms of asthmatic children--a double-blind controlled trial

BACKGROUND

Inhalation of house dust mite (HDM) allergen may provoke attacks of asthma.

OBJECTIVE

We investigated whether a double-blind placebo-controlled community-based study aimed at reducing the HDM allergens in the bedrooms of HDM sensitive asthmatic children using the best methods available would prove beneficial to the children's health.

METHODS

The children (mean age 9.9 years, 34 boys) were recruited by a questionnaire submitted to 7386 families in a geographically-defined area of the UK. Subjects were chosen to take part in the double-blind placebo-controlled trial if they were asthmatic, skin sensitive to mites, and had mite allergen in their mattresses. Seventy children were randomly allocated to groups. In the active group, the children's bedrooms were treated with an acaricide (Acarosan) and the mattresses, pillows and duvets were encased in exclusion covers. The control group received placebo treatments.

RESULTS

Forty-nine complete data sets were obtained. Applying bedding covers and Acarosan led to a median reduction of 480 ng (100%) in mite allergen on the mattress vs 215 ng (53%) reduction in placebo-treated group by 6 weeks. No evidence was found that the acaricide reduced mite allergen level. A change in bronchial reactivity to histamine was observed in the children after 6 weeks. This was not associated with any change in thrice-daily records of peak expiratory flow rate. By 24 weeks, the actively-treated children had improved forced expiratory volume in 1s (FEV1) and fewer required bronchodilator therapy or reported asthmatic symptoms than did the controls.

CONCLUSIONS

The results suggest that mite removal procedures may modestly improve mite-sensitive asthmatics and could perhaps be of value in exceptionally mite-sensitive and/or highly mite-exposed individuals whose response to the attempted removal should be measured.

The effects of interleukin-1 receptor antagonist protein (IRAP) infusion following spinal cord transection in rats

A laminectomy was performed at the T5-T6 vertebral level in adult, male, Sprague-Dawley rats and the spinal cord transected with a scalpel. A group of sham animals was subjected to the same surgery without the transection step. A group of unhandled control rats was also included. A subgroup of transected animals received a subcutaneous osmotic minipump that dispensed IL-1 receptor antagonist protein (IRAP) at the transection site for 7 consecutive days. Another transected subgroup received a minipump that infused the vehicle only. IRAP-treated rats displayed a significant reduction in body temperature (p < 0.05) compared with vehicle-treated rats. The IRAP-treated rats were also less active when assessed for locomotor behavior using an HVS computerized tracking system (p < 0.01). IRAP treatment had no effect on serum corticosterone, beta-endorphin levels, Con A, PHA, or LPS-induced splenocyte mitogenesis when compared with vehicle-treated animals. However, half of the IRAP-treated animals exhibited a substantive reduction in the number of reactive astrocytes near the transection site, suggesting a possible effect of IRAP on astrocyte activation.

Renal transplantation in patients undergoing chronic peritoneal dialysis

OBJECTIVE

To review the outcome of renal transplantation in a group of patients treated with chronic peritoneal dialysis and to compare the results with those of a matched population on hemodialysis.

DESIGN

Retrospective study.

SETTING

Tertiary, institutional hospital, administering to a population of two million, with 100 patients on peritoneal dialysis. Six hundred and sixty renal transplantations were performed by the end of 1993.

PATIENTS

Fifty-six patients on chronic peritoneal dialysis who received 58 cadaveric renal allografts were compared to 58 patients on hemodialysis who received a graft from the same donor (n = 39), or the transplant next to the one performed to the corresponding patient on peritoneal dialysis (n = 19).

RESULTS

Patients on peritoneal dialysis showed a lower rate of delayed graft function (24.1 vs 50%, p < 0.05) and a similar incidence of acute rejection than patients on hemodialysis. Also, peritoneal dialysis patients received less supplementary immunosuppression, suffered a lower incidence of late infections (0.93 vs 0.58 episodes/patient), and had a similar incidence of dialysis-related complications (0.25 vs 0.20 episodes/patient).

CONCLUSIONS

Patients on peritoneal dialysis do well after renal transplantation. The incidence of some complications, particularly delayed graft function, is lower than in patients on hemodialysis, while the incidence of dialysis-associated complications is similar in both groups.

Deep-frozen allogeneic cancellous bone grafts in 10 dogs: a case series

Deep-frozen, aseptically collected and processed allogeneic cancellous bone was implanted in eight dogs during the surgical repair of diaphyseal long bone fractures and in two dogs during arthrodeses. A combined allogeneic and autogeneic cancellous bone graft was used in two fractures with a segmental bone loss of more than 5 cm. Bone union occurred in five fractures and in both arthrodeses. Failure of fixation occurred in two dogs with nonunion fractures and in a third dog with an open, infected fracture. Biopsies from the fracture sites were obtained from these dogs following failure of their fracture fixation. The cancellous bone graft appeared to be in the process of normal incorporation in each case. Failure of fixation was attributed to technical or case management errors or both, in each of the three fractures that failed to achieve bony union. Frozen allogeneic cancellous bone grafts were effectively incorporated when used in the primary repair of fractures and arthrodeses. Combined autogenous and allogeneic cancellous bone grafts may be particularly useful in the repair of fractures with large segmental diaphyseal bone defects. The use of allogeneic cancellous bone grafts in nonunion fractures requires further investigation before it can be recommended.

Splice site mutation causing deletion of exon 21 sequences from the pro alpha 2(I) chain of type I collagen in a patient with severe dentinogenesis imperfecta but very mild osteogenesis imperfecta

An eight-year-old boy was referred for dental assessment of dentinogenesis imperfecta, a full clinical examination also revealed joint hypermobility and some features of mild osteogenesis imperfecta although he had suffered few fractures. Analysis of the collagens produced by both gingival and skin fibroblast cultures showed the synthesis and intracellular retention of an abnormal alpha 2(I) chain that migrated faster than normal on SDS-PAGE. Cyanogen bromide peptide mapping of this intracellular protein indicated a probable deletion in the N-terminal peptide alpha 2CB4. The denaturation temperature of the mutant protein was only 36 degrees C, some 6 degrees C below normal. At 37 degrees C secretion of abnormal protein was not detectable but a lower temperature (30 degrees C) some was secreted into the medium. RT-PCR amplification of mRNA coding for alpha 2CB4 revealed a heterozygous deletion of the 108 bp exon 21 of COL1A2. Sequencing of PCR amplified genomic DNA identified a G --> A transition in the moderately conserved + 5 position of the IVS 21 5' consensus splice site causing the skipping of exon 21. Hybridization with allele-specific oligonucleotides showed no other family member had this base change. Since the cDNA deletion was associated with the (-) allele of a Pvu II polymorphism in exon 25 of COL1A2 we could demonstrate that the mutant pre-mRNA was alternatively spliced yielding both full length and deleted transcripts. Family genotype analysis indicated the mutation had originated in the paternal alpha 2(I) gene.

A combined approach to reduce mite allergen in the bedroom

BACKGROUND

Asthma is a common chronic disease of childhood. House dust mite (HDM) are known to be a major source of allergen affecting atopic asthmatics. No single control method has been demonstrated to consistently reduce asthma.

OBJECTIVE

We investigated the effect of a combination of two methods of HDM allergen control on HDM allergen content in the bedding and carpets of asthmatic children.

METHODS

This was a double-blind placebo-controlled trial treating the bedrooms of 56 mite-sensitive asthmatic children. The carpet and the mattress, duvet and pillows (bedding) in the bedroom of children of the active group were treated with the acaricide Acarosan (benzyl benzoate). The bedding was then encased in vapour permeable waterproof fabric (Intervent--cotton coated with polyurethane) for 24 weeks. The carpet and bedding of the control group were treated with placebo and the bedding encased in cotton covers for 24 weeks. Dust samples were collected from all these items in a standard manner at regular intervals and Der p I content analysed.

RESULTS

The group with active treatment had a median reduction of 480 ng (100%) in mite allergen from the mattress vs 215 ng (53%) reduction in placebo-treated group by 6 weeks. The Der p I content of the active group's bedding was always less than the placebo group after treatment (P < 0.01). The acaricide applied to the carpets or inside the mattress covers was ineffective in reducing allergen content.

CONCLUSION

This study confirms the effectiveness of encasing covers in reducing the mite allergen exposure but indicates there is no further advantage in applying acaricide simultaneously.

Aberrant p53 expression predicts clinical resistance to cisplatin-based chemotherapy in locally advanced non-small cell lung cancer

The development of cisplatin-based induction chemotherapy followed by surgical resection or radiation has improved the poor prognosis of stage III non-small cell lung cancer (NSCLC). In vitro studies indicate that p53 can modulate cisplatin-induced cytotoxicity, but the molecular genetic features determining response or resistance to cisplatin in vivo must be defined. For this reason, tumor specimens from 52 patients with stage IIIA NSCLC entered in a prospective clinical trial of cisplatin-based induction chemotherapy followed by surgical resection were examined for p53 expression by immunohistochemical staining before and after induction chemotherapy. p53 expression was correlated with clinical and pathological response using Fisher's exact test. No correlation was established between p53 expression and clinical response because 47 of the 52 patients studied had a major response. However, a significant association was observed between aberrant p53 expression and resistance to chemotherapy as assessed by pathological response. Only 3 of the 20 patients whose tumors exhibited a high level (+ + to + + + +) of p53 staining experienced a major (+ + + to + + + +) pathological response to chemotherapy. Only 7 of 52 cases examined before and after chemotherapy treatment exhibited a change in the level of p53 expression after cisplatin-based chemotherapy. These results indicate that cisplatin alters p53 expression infrequently and suggest a direct link between aberrant p53 expression and resistance to cisplatin-based chemotherapy in NSCLC.

Mitral annular calcification in CAPD patients with a low degree of hyperparathyroidism. An analysis of other possible risk factors

Chronic renal failure has been suggested as a risk factor for mitral annular calcification (MAC), a degenerative process of the mitral annulus. The objective of the present study was to define MAC risk factors at the start of dialysis and 'de-novo' appearance after medium- or long-term CAPD, in a non-selected population (135 patients) with a low degree of secondary hyperparathyroidism. Echocardiographic studies were performed at the beginning of CAPD and every 1-1.5 years thereafter. Diagnosis of MAC was established by M mode and 2-D study. Seventeen of 135 patients studied at the start of dialysis showed MAC. Patients who showed MAC were older and presented a higher mean systolic blood pressure. The other anthropometric/demographic parameters did not show statistically significant differences. MAC thickness: mean 6.21 +/- 3.65 mm (range 3-17.2 mm). The posterior annulus was universally affected and in four patients the anterior annulus was involved. Seventeen of 76 patients included in the follow-up study developed MAC. No significant differences for demography, except age, with MAC patients being older, were found. Mean time on CAPD until de-novo MAC diagnosis was 49.7 +/- 26.9 months. MAC thickness: mean 4.97 +/- 1.6 mm (range 3-8.42 mm). The posterior annulus was affected in all patients except for one and in four patients the anterior annulus was involved. The most remarkable echocardiographic feature is the almost constant association of MAC with left atrial dilatation (LAD). The last one does not seem a consequence of mitral insufficiency, or systolic dysfunction. Left ventricular hypertrophy was universally found, with no different intensities for patients with or without MAC. In conclusion, a high incidence of mitral annular calcification has been found in CAPD patients. Our data do not confirm the role of classical invoked risk factors. Blood CaP product under 75, a moderate to mild degree of hyperparathyroidism and/or hypertension with left ventricular hypertrophy do not seem to be isolated risk factors during the CAPD period. Length of time on CAPD, for unknown reasons, seems to favour the appearance of MAC. At starting dialysis, high systolic blood pressure and left ventricular hypertrophy seem to be related to MAC. Diabetes appears to represent an additional risk factor. Further research on mitral annular calcification pathogenesis and its consequences is urgently required.

Choroidal responses in microgravity. (SLS-1, SLS-2 and hindlimb-suspension experiments)

Fluid and electrolyte shifts occurring during human spaceflight have been reported and investigated at the level of blood, cardiovascular and renal responses. Very few data were available concerning the cerebral fluid and electrolyte adaptation to microgravity, even in animal models. It is the reason why we developed several studies focused on the effects of spaceflight (SLS-1 and SLS-2 programs, carried on NASA STS 40 and 56 missions, which were 9- and 14-day flights, respectively), on structural and functional features of choroid plexuses, organs which secrete 70-90% of cerebrospinal fluid (CSF) and which are involved in brain homeostasis. Rats flown aboard space shuttles were sacrificed either in space (SLS-2 experiment, on flight day 13) or 4-8 hours after landing (SLS-1 and SLS-2 experiments). Quantitative autoradiography performed by microdensitometry and image analysis, showed that lateral and third ventricle choroid plexuses from rats flown for SLS-1 experiment demonstrated an increased number (about x 2) of binding sites to natriuretic peptides (which are known to be involved in mechanisms regulating CSF production). Using electron microscopy and immunocytochemistry, we studied the cellular response of choroid plexuses, which produce cerebrospinal fluid (CSF) in brain lateral, third and fourth ventricles. We demonstrated that spaceflight (SLS-2 experiment, inflight samples) induces changes in the choroidal cell structure (apical microvilli, kinocilia organization, vesicle accumulation) and protein distribution or expression (carbonic anhydrase II, water channels,...). These observations suggested a loss of choroidal cell polarity and a decrease in CSF secretion. Hindlimb-suspended rats displayed similar choroidal changes. All together, these results support the hypothesis of a modified CSF production in rats during long-term (9, 13 or 14 days) adaptations to microgravity.