Platelet sequestration and activation during GalTKO.hCD46 pig lung perfusion by human blood is primarily mediated by GPIb, GPIIb/IIIa, and von Willebrand Factor.

BACKGROUND: Here, we ask whether platelet GPIb and GPIIb/IIIa receptors modulate platelet sequestration and activation during GalTKO.hCD46 pig lung xenograft perfusion. METHODS: GalTKO.hCD46 transgenic pig lungs were perfused with heparinized fresh human blood. Results from perfusions in which αGPIb Fab (6B4, 10 mg/l blood, n = 6), αGPIIb/IIIa Fab (ReoPro, 3.5 mg/l blood, n = 6), or both drugs (n = 4) were administered to the perfusate were compared to two additional groups in which the donor pig received 1-desamino-8-d-arginine vasopressin (DDAVP), 3 µg/kg (to pre-deplete von Willebrand Factor (pVWF), the main GPIb ligand), with or without αGPIb (n = 6 each). RESULTS: Platelet sequestration was significantly delayed in αGPIb, αGPIb+DDAVP, and αGPIb+αGPIIb/IIIa groups. Median lung "survival" was significantly longer (>240 vs. 162 min reference, p = 0.016), and platelet activation (as CD62P and ßTG) were significantly inhibited, when pigs were pre-treated with DDAVP, with or without αGPIb Fab treatment. Pulmonary vascular resistance rise was not significantly attenuated in any group, and was associated with residual thromboxane and histamine elaboration. CONCLUSIONS: The GPIb-VWF and GPIIb/IIIa axes play important roles in platelet sequestration and coagulation cascade activation during GalTKO.hCD46 lung xenograft injury. GPIb blockade significantly reduces platelet activation and delays platelet sequestration in this xenolung rejection model, an effect amplified by adding αGPIIb/IIIa blockade or depletion of VWF from pig lung.

Clinical care versus ethical obligations: HIV-1 and -2 co-infection with hepatitis B in a pregnant Jehovah's Witness.

Co-infection with HIV-1 and -2 is rare, even in west Africa. We present the case of a 38-year-old pregnant Jehovah's Witness presenting late in pregnancy with triple infection with HIV-1, HIV-2 and hepatitis B virus. There was a successful outcome in averting vertical transmission despite objections to management based on religious and cultural beliefs.

Managing vaccines: defining the remit of primary care and specialist HIV clinics in the delivery of immunization to individuals with HIV infection.

The British HIV Association (BHIVA) has published guidelines for immunization of HIV-infected adults. A chart review of 200 HIV-infected patients diagnosed was conducted to determine shortcomings in previous practice and determine which vaccines should routinely be given in specialist HIV clinics and which might be able to be delegated to primary care clinics. Data were collected on administration of three categories of vaccinations: (1) vaccines used in all individuals with chronic disease (pneumococcal, influenza, swine flu H1N1); (2) targeted vaccinations used in non-immune individuals with HIV who are at risk of exposure (hepatitis A and hepatitis B); (3) routine vaccines traditionally delivered to the whole population (measles/mumps/rubella [MMR], diphtheria/tetanus/pertussis and meningitis C/ACWY). Pneumococcal vaccine was delivered to 54% of eligible patients, 52% of eligible individuals completed a full hepatitis B programme of vaccination and 21% (42/200) were naturally immune; hepatitis A vaccine was delivered to 36% of eligible individuals. With increasing demands on resources, it seems likely that HIV services will have to harness resources of primary care in vaccine programmes in relation to routine vaccines. By improving communication between primary and secondary care mistakes with live vaccination decisions could be avoided; HIV services should continue to perform targeted and chronic disease vaccines, i.e. for category 1 and category 2 vaccines.

Acute hepatitis B: the limits of maintaining patient confidentiality.

Household contacts of hepatitis B (HBV) are at risk of infection, and guidelines advise vaccination of these contacts in addition to sexual partners (along with traditional high-risk groups). We present a case of intrafamilial transmission of acute hepatitis B virus (HBV) following failure to self-disclose status to family members. Complex confidentiality issues can arise following a diagnosis of HBV infection.

The effect of gravity on the horizontal and vertical vestibulo-ocular reflex in the rat.

Horizontal and vertical eye movements were recorded in alert pigmented rats using chronically implanted scleral search coils or temporary glue-on coils to test the dependence of the vestibulo-ocular reflex (VOR) upon rotation axis and body orientation. The contributions of semicircular-canal versus otolith-organ signals to the VOR were investigated by providing canal-only (vertical axis) and canal plus otolith (horizontal axis) stimulation conditions. Rotations that stimulated canals only (upright yaw and nose-up roll) produced an accurate VOR during middle- and high-frequency rotations (0.2-2 Hz). However, at frequencies below 0.2 Hz, the canal-only rotations elicited a phase-advanced VOR. The addition of a changing gravity stimulus, and thus dynamic otolith stimulation, to the canal signal (nose-up yaw, on-side yaw, and upright roll) produced a VOR response with accurate phase down to the lowest frequency tested (0.02 Hz). In order to further test the dependence of the VOR on gravitational signals, we tested vertical VOR with the head in an inverted posture (inverted roll). The VOR in this condition was advanced in phase across all frequencies tested. At low frequencies, the VOR during inverted roll was anticompensatory, characterized by slow-phase eye movement in the same direction as head movement. The substantial differences between canalonly VOR and canal plus otolith VOR suggest an important role of otolith organs in rat VOR. Anticompensatory VOR during inverted roll suggests that part of the otolith contribution arises from static tilt signals that are inverted when the head is inverted.

Double-blind, randomised, placebo-controlled, dose-finding study of oral ibandronate in patients with metastatic bone disease.

BACKGROUND: Bisphosphonates are an important component of the treatment of metastatic bone disease but more potent, oral formulations are required to improve the effectiveness and convenience of treatment. An oral formulation of the new bisphosphonate, ibandronate (BM 21.0955) has recently been developed. PATIENTS AND METHODS: One hundred ten patients with bone metastases (77 breast, 16, prostate, 3 myeloma, 14 others) were recruited from a single institution to this double blind placebo-controlled evaluation of four oral dose levels (5, 10, 20 and 50 mg) of ibandronate. No changes in systemic anti-cancer treatment were allowed in the month before commencing treatment or during the study period. After an initial four-week tolerability phase, patients could continue on treatment for a further three months without unblinding; patients initially allocated to placebo received ibandronate 50 mg. The primary endpoint was urinary calcium excretion (UCCR). Bone resorption was also assessed by measurement of pyridinoline (Pyr), deoxypyridinoline (Dpd), and the N-terminal (NTX) and C-terminal (Crosslaps) portions of the collagen crosslinking molecules. RESULTS: Two patients did not receive any trial medication thus, 108 patients were evaluable for safety. Ninety-two patients were evaluable for efficacy. A dose dependent reduction was observed in both UCCR and collagen crosslink excretion. At the 50 mg dose level, the percentage reductions from baseline in UCCR, Pyr, Dpd, Crosslaps and NTX were 71%, 28%, 39%, 80% and 74% respectively. One or more gastrointestinal (GI) adverse events occurring in the first month of treatment were reported by six (30%), seven (33%), nine (39%), nine (41%) and eleven (50%) patients at the placebo, 5, 10, 20 and 50 mg dose levels respectively. One patient (20 mg dose) developed radiographically confirmed oesophageal ulceration. GI tolerability may have been adversely affected by concomitant administration of non-steroidal anti-inflammatory agents. Nine (8%) patients stopped treatment within the first month due to GI intolerability but these patients were evenly distributed across the five treatment groups. There was no difference in non-GI adverse events between groups. CONCLUSIONS: Oral ibandronate has potent effects on the rate of bone resorption at doses which are generally well tolerated. Further development is appropriate to evaluate the effects of long-term administration in the prevention of metastatic bone disease and the management of established skeletal metastases.

Modeling learning in brain stem and cerebellar sites responsible for VOR plasticity.

A simple model of vestibuloocular reflex (VOR) function was used to analyze several hypotheses currently held concerning the characteristics of VOR plasticity. The network included a direct vestibular pathway and an indirect path via the cerebellum. An optimization analysis of this model suggests that regulation of brain stem sites is critical for the proper modification of VOR gain. A more physiologically plausible learning rule was also applied to this network. Analysis of these simulation results suggests that the preferred error correction signal controlling gain modification of the VOR is the direct output of the accessory optic system (AOS) to the vestibular nuclei vs. a signal relayed through the cerebellum via floccular Purkinje cells. The potential anatomical and physiological basis for this conclusion is discussed, in relation to our current understanding of the latency of the adapted VOR response.

Chronic recording of the vestibulo-ocular reflex in the restrained rat using a permanently implanted scleral search coil.

A technique is described which allows accurate long-term monitoring of eye movements in the rat using permanently implanted scleral search coils. Search coils permanently sutured around the sclera yield vestibulo-ocular reflex (VOR) gain and phase values which are comparable to those reported previously in the literature using acutely implanted coils or electrooculographic electrodes. Considerations related to strain, sex and surgical procedures which permit measurement of responses in the chronically restrained rat are described. VOR gain and phase show a time course to their recovery following the implant surgery, with asymptotic performance typically attained approximately 10 days post-surgically. This technique, with the ability to monitor eye movements over weeks to months, appears ideal for development of rodent models of reflex adaptation which require observation of reflex behavior over extended periods of time. Development of a chronic procedure for monitoring eye movement in rodents is especially important given their initial response to restraint (extensive struggling). Finally, adaptation of this technique to smaller species (e.g., mouse) appears technically feasible which should permit the application of transgenic and knockout techniques to the determination of various vestibular reflex functions requiring long-term monitoring.

Classical conditioning using vestibular reflexes.

Adaptation of the vestibulo-ocular reflex (VOR) is one of the principal models for studying motor learning in the mammalian CNS. However, there has been no previous comprehensive attempt to understand the behavioral characteristics of VOR adaptation in terms of traditional psychological learning theory. To accomplish this objective, the effectiveness of vestibular-evoked responses in serving as the conditioned or unconditioned stimulus in classical conditioning paradigms is first reviewed. Then, the various procedures for eliciting VOR adaptation are reviewed from the perspective of their similarity to standard classical conditioning protocols. A systematic analysis of Western and Russian literature yielded a relatively small number of studies that explicitly used vestibular reflexes in classical conditioning paradigms, and they report a wide range in success. Potential explanations for these diverse findings are discussed. A comprehensive categorization of the behavioral parallels between VOR adaptation and classical conditioning is then presented. Viewing VOR adaptation as a form of classical conditioning is a useful heuristic device and leads directly to the description of further behavioral experiments that could throw additional light on general mechanisms for inducing neural plasticity. Such an exercise is of benefit in order to further understand the common framework which might exist between VOR adaptation and other models of motor learning (for example, rabbit eye blink conditioning).

Processing of spatial information by floccular and non-floccular target neurons in the alert cat.

In five alert chronically-prepared cats we studied the response to sinusoidal 3-D whole body rotation of well-isolated vestibular nucleus neurons which were tested for monosynaptic input from the vestibular labyrinth, direct projection to the oculomotor nucleus and, in some cases, inhibition from cerebellar flocculus stimulation. Neurons directly inhibited by flocculus stimulation had significantly greater horizontal-vertical semicircular canal signal convergence than did neurons not inhibited by flocculus stimulation.

Alterations in rat horizontal vestibulo-ocular reflex phase as a function of orientation in gravity.

The effect of changes in static and dynamic gravity signals on the phase accuracy of the horizontal vestibulo-ocular reflex (HVOR) was studied in rats using chronically implanted scleral search coils to monitor eye movements. Rats were sinusoidally rotated using a range of different frequencies (0.035-2 Hz) in a plane which always activated the horizontal semicircular canals but in one of three different orientations with regard to gravity which differentially activated the otolith organs: 1) upright-normal static gravity signal, no dynamic otolith activation; 2) inverted-inverted static gravity signal, no dynamic otolith activation; 3) on-side-dynamic activation of the otolith organs. In the upright orientation, the HVOR shows a phase advance at 0.2 Hz and below but not at 0.5 Hz and above. Phase accuracy of the HVOR was further degraded in the inverted orientation with rats showing large phase leads at 0.2 Hz and below. In contrast, accuracy of the HVOR was significantly improved at 0.2 Hz and below in the on-side orientation with phase accurate eye movements down to the lowest frequency tested. The results further support the idea that otolith organs play an important role in VOR generation by supplementing the semicircular canals' response to angular head movements.

Ontogenic and nutritional changes in circulating insulin-like growth factor (IGF)-I, IGF-II and IGF-binding proteins in growing ewe and ram lambs.

The ontogeny of the IGF endocrine system was investigated in 15 young lambs before and after weaning at 62 days of age. Before weaning, plasma IGF-I concentrations were higher in rams than ewes, and plasma concentrations of IGF-II and IGF-binding protein-3 (IGFBP-3) also tended to be higher in rams than in ewes. Feed intake of ewes and rams was restricted after weaning to remove sex differences in feed intake. Plasma concentrations of IGF-I and IGFBP-3 did not differ between rams and ewes at 100 days of age, but plasma IGF-II was higher in rams than in ewes at this time. Since circulating concentrations of GH were higher in rams than in ewes at 100 days of age, this implies that the restricted feed intake blocked the IGF-I and IGFBP-3 responses to GH. We conclude that sex differences in circulating IGF-I and IGFBP-3 concentrations in the growing lamb alter with age, and are not present when nutrition is restricted.

Glutathione reduces the toxicity and improves quality of life of women diagnosed with ovarian cancer treated with cisplatin: results of a double-blind, randomised trial.

BACKGROUND: Early clinical trials have suggested that glutathione (GSH) offers protection from the toxic effects of cisplatin. PATIENTS AND METHODS: One hundred fifty-one patients with ovarian cancer (stage I-IV) were evaluated in a clinical trial of cisplatin (CDDP) +/- glutathione (GSH). The objective was to determine whether GSH would enhance the feasibility of giving six cycles of CDDP at 100 mg/m2 without dose reduction due to toxicity. RESULTS: When considering the proportion of patients receiving six courses of CDDP at any dose, GSH produced a significant advantage over control--58% versus 39%, (P = 0.04). For these patients there was a significant difference between the reduction in creatinine clearance for GSH treated patients compared with control--74% versus 62% (P = 0.006). Quality of life scores demonstrated that for patients receiving GSH there was a statistically significant improvement in depression, emesis, peripheral neurotoxicity, hair loss, shortness of breath and difficulty concentrating. As an indication of overall activity, these patients were statistically significantly more able to undertake housekeeping and shopping. Clinically assessed response to treatment demonstrated a trend towards a better outcome in the GSH group (73% versus 62%) but this was not statistically significant (P = 0.25). CONCLUSIONS: The results demonstrate that adding GSH to CDDP allows more cycles of CDDP treatment to be administered because less toxicity is observed and the patient's quality of life is improved.

Regulation of gastrointestinal growth in fetal sheep by luminally administered insulin-like growth factor-I.

Fetuses swallow large volumes of amniotic fluid. Absence of swallowing results in gastrointestinal tract (GIT) growth deficits. While it is not yet known to what extent the growth factors present in amniotic fluid are involved in GIT ontogeny, milk-derived growth factors are considered to be important for neonatal growth. Our experiment tested the hypothesis that a luminal growth factor (insulin-like growth factor-I, IGF-I) can sustain or promote GIT growth in utero in a model of gastrointestinal tract growth retardation. Ten-day infusion of either human recombinant IGF-I or vehicle into twin fetal sheep at 80 days gestation via an indwelling esophageal catheter resulted in altered GIT growth. Weight of the forestomach and small intestine increased. Significant histological changes were noted in the proximal small intestine, i.e. the region most exposed to the luminal infusion. Mucosal tissues were reduced in size. While the enterocytes in the proximal small intestine were generally more mature with regard to the ontogeny of the apical endocytic complex (which is responsible for uptake and transport of whole peptides), there were also many abnormal cytological features present. These included the development of large lysosomal-like inclusion bodies and many surfactant-like particles within the apical cytoplasm. Plasma IGF-I levels were on average 20% higher in treated siblings, suggesting that luminal IGF-I crossed the fetal gut and entered blood. IGF-II levels were not significantly affected. These observations are consistent with the suggestion that growth factors, which are present in swallowed amniotic fluid, influence fetal ontogeny.

Loop diuretics in the management of acute renal failure: a prospective, double-blind, placebo-controlled, randomized study.

BACKGROUND: Studies on the role of loop diuretics in patients with acute renal failure (ARF) are largely retrospective, anecdotal, and poorly controlled. We report the results of a prospective, randomized, placebo-controlled, double-blind study examining the effect of loop diuretics on renal recovery, dialysis, and death in patients with ARF. METHODS: Ninety-two patients with ARF were enrolled into the study. All received intravenous dopamine, 2 micrograms/kg body weight/min throughout, 20% mannitol, 100 ml every 6 h for the first 3 days, and, in a double-blind manner, either torasemide, frusemide, or placebo, 3 mg/kg body weight i.v. every 6 h for 21 days or until renal recovery or death. RESULTS: Renal recovery, the need for dialysis, and death were no different in the three groups. Patients given a loop diuretic had a significant rise in urine flow rate in the first 24 h compared to placebo (P = 0.02). Based on the urine flow rate during the first post-medication day patients were divided into two groups--oliguric (< 50 ml/h) and non-oliguric (> or = 50 ml/h). Non-oliguric patients had a significantly lower mortality than oliguric patients (43% vs 69%, P = 0.01). However, they were less ill (APACHE II score 17.2 vs 20.6, P = 0.008) and had less severe renal failure at entry (creatinine clearance 14 ml/min vs 4 ml/min, P < 0.0001). CONCLUSION: The use of loop diuretics in oliguric patients with ARF can result in a diuresis. There is no evidence that these drugs can alter outcome.

Intravenous infusion of insulin-like growth factor I in fetal sheep reduces hepatic IGF-I and IGF-II mRNAs.

Liver contains the highest concentrations of insulin-like growth factor (IGF) I mRNA in adult rats and sheep and is a major source of circulating IGF-I. In rats, inhibition of hepatic IGF-I production by exogenous IGF-I has been reported. In fetal sheep, skeletal muscle and liver are major sites of IGF-I synthesis and potential sources of circulating IGF-I. To determine whether feedback inhibition of IGF gene expression in fetal liver or muscle by IGF-I occurs, IGF-I and IGF-II mRNAs were measured in these tissues after intravenous infusion of recombinant human IGF-I into fetal sheep. Infusion of IGF-I (26 +/- 4 micrograms.h-1.kg-1; n = 6) or saline (n = 6) commenced on day 120 of pregnancy (term = 150 days) and continued for 10 days. Plasma concentrations of IGF-I were threefold higher in infused fetuses at 130 days of gestation (P < 0.0003), whereas those of IGF-II were unchanged. IGF-I infusion reduced the relative abundance of IGF-I mRNA (P < 0.0002) and IGF-II mRNA (P < 0.01) in fetal liver by approximately 50% but did not alter IGF-I or IGF-II mRNA in skeletal muscle. These results indicate that IGF-I inhibits the expression of both IGF-I and IGF-II genes in fetal liver and that IGF gene expression in fetal liver and muscle is differentially regulated by IGF-I.

Sexual dimorphism of circulating somatotropin, insulin-like growth factor I and II, insulin-like growth factor binding proteins, and insulin: relationships to growth rate and carcass characteristics in growing lambs.

The effects of sex and age on patterns of circulating somatotropin (ST) concentration and plasma IGF-I, IGF-II, insulin, and IGF binding protein-3 (IGFBP-3) were studied in ram, wether, and ewe lambs (n = 7 or 8) sampled at mean ages of 81 (I1) and 158 d (I2). Between 81 and 158 d of age, rams grew more rapidly than wethers (P < .01), and wethers grew more rapidly than ewes (P < .01). The sex differences in growth were reflected in empty body weight at slaughter: rams > wethers > ewes (P < .05). Mean plasma ST concentrations, ST pulse amplitude, and integrated plasma ST concentrations were greater (P < .05) in rams than in ewes at I1 and I2. Characteristics of the ST plasma profile in wethers were generally intermediate between those of rams and ewes. The interpulse interval was greater in ewes than in wethers at I2. The IGF-I and IGFBP-3 concentrations were greater in rams than in ewes at both sampling times. Plasma IGF-II was greater in ewes than in rams at I2. Mean plasma ST was approximately two thirds less at I2 than at I1 regardless of sex. Mean plasma ST and IGF-I at both ages were positively correlated with growth. Mean plasma ST at I2 was negatively correlated with fatness at slaughter. Sex and age significantly affected patterns of circulating ST and concentrations of IGF-I and IGFBP-3 in prepubertal growing lambs, under conditions for which growth rates and composition were also sexually dimorphic.

Changes in sensitivity of vestibular nucleus neurons induced by cross-axis adaptation of the vestibulo-ocular reflex in the cat.

In alert, chronically-prepared cats, we studied response characteristics of well-isolated vestibular nucleus neurons (n = 9) while pairing yaw rotation with a pitch optokinetic stimulus, resulting in cross-axis adaptation of the horizontal vestibulo-ocular reflex. Each neuron's sensitivity to whole body rotation in a variety of axes in three-dimensional space was determined. When tested in darkness following adaptation, neurons showed statistically significant increases in sensitivity to yaw but not vertical plane rotations, suggesting participation in reflex plasticity.