The neuroprotective effects of the recombinant interleukin-1 receptor antagonist rhIL-1ra after excitotoxic stimulation with kainic acid and its relationship to the amyloid precursor protein gene

The cytokine interleukin-1 (IL-1) and its endogenous antagonist (IL-1ra) have important functions in the central nervous system. Recent experimental observations have suggested that recombinant IL-1RA (rhIL-1ra) has neuroprotective properties in ischaemia, excitotoxicity, and trauma. We wished to see what effect rhIL-1ra had on kainic acid-induced neuronal death and to investigate how this might relate to changes in expression of the amyloid precursor protein gene (APP) and glial fibrillary acid protein (GFAP) using in situ hybridization. Wistar rats were treated by intracerebroventricular administration with rhIL-1ra at doses of 10, 20 and 40 microg given 10 min before and 10 min after intraperitoneal kainic acid 10 mg/kg. Behaviour was measured and, after 10 days, the brains were removed for histology and in situ hybridization. There were no anticonvulsant effects on kainic acid-induced wet dog shakes or limbic motor seizures. There were no differences in the effects of rhIL-1ra at all doses tested on hippocampal temperature, blood pressure, blood gases, pH, and glucose in comparison to control. With rhIL-1ra 10 microg given twice, there was significant protection of neurons in the CA1 and CA3 field of the hippocampus and dorsal thalamus, but not in the primary olfactory cortex-amygdaloid region. Small, but insignificant, neuroprotective effects were observed in the same anatomical regions with a dose of 20 microg given twice, and no neuroprotective effects were observed with 40 microg. The enhanced neuronal survival in CA1, CA3 and the dorsal thalamus was associated with preservation of APP 695 mRNA (neuronal form) and lack of stimulation of APP 770 (glial form) and GFAP messages. Where there was no neuroprotection APP 695 mRNA was reduced and stimulation of both APP 770 and GFAP mRNAs was observed. In conclusion, rhIL-1ra has dose- and region-dependent effects on neuronal survival after kainic acid and prevents damage-induced changes in APP and GFAP mRNAs.

Characterization of a pH-sensitive surfactant, dodecyl-2-(1'-imidazolyl) propionate (DIP), and preliminary studies in liposome mediated gene transfer

The inefficiency of non-viral gene delivery systems, relative to viral systems, is likely due, in part, to the failure of endosomes to release DNA before reaching degradative lysosomes. A solution is to incorporate compounds in a delivery vector that will selectively increase the release of endosomally encapsulated DNA. To meet the above criteria, we designed, synthesized, and characterized the physicochemical and biological properties of such a compound, dodecyl-2-(1'-imidazolyl) propionate (DIP) to enhance cationic liposome mediated gene delivery. Several surface active techniques were used to characterize DIP lysing membranes. The critical micelle concentration of DIP was between 0.10-0.18 mM and the effective release and solubilization ratios were 1.0 and 4.0, respectively. DIP facilitated membrane disruption in both a pH and concentration dependent manner. In the presence of esterase at pH 7.0, the hydrolysis rate increased 32-fold indicating DIP can be degraded in the biological milieu. Toxicity of DIP by MTT assay in the SKnSH cell line demonstrated an ID50 of 1.2 mM, which is 30-fold higher than the concentration of DIP used to enhance gene transfection. When incorporated into cationic-liposomes, DIP enhanced transgene expression in vitro by 5-fold. The results of the study indicate that DIP may be a useful adjuvant to increase non-viral gene delivery to cells.

Xenografting: ethical issues

This paper considers the ethical issues raised by xenotransplantation under four headings: interfering with nature; effects on the recipient; effects on other humans; and effects on donor animals. The first two issues raise no insuperable problems: charges of unnaturalness are misguided, and the risks that xenotransplantation carries for the recipient are a matter for properly informed consent. The other two issues raise more serious problems, however, and it is argued that if we take seriously the risk of transferring new infectious agents from animal to human populations and the interests of donor animals, then a moratorium on xenotransplantation is called for. The paper finds that the recent Nuffield Council and Department of Health reports on xenotransplantation are insufficiently cautious in the conclusions that they draw from these considerations.

Parental anxiety due to abnormal behaviour following withdrawal of sedation

Abnormal behaviour has been previously reported on withdrawal of sedation in critically-ill children. This description of a child who had prolonged withdrawal symptoms lasting almost 2 weeks includes a report on his parent's comments in relation to the anxiety they felt while he was behaving abnormally. Health professionals need to be aware of the severe nature of this withdrawal reaction and its effect on the parents.

DQAsomes: a novel potential drug and gene delivery system made from Dequalinium

PURPOSE

Dequalinium, a drug known for over 30 years, is a dicationic amphiphile compound resembling bolaform electrolytes. The purpose of our work was to determine the state of aggregation of dequalinium in aqueous medium and to investigate both, its ability to bind DNA and its potential to serve as a novel non-viral transfection vector.

METHODS

The form of aggregation was determined employing electron microscopic techniques. The DNA binding capacity of dequalinium was assayed using SYBR Green I stain. For in vitro cell transfection experiments plasmid DNA encoding for firefly luciferase was used.

RESULTS

Dequalinium forms in aqueous medium liposome-like aggregates, which we term DQAsomes. These dequalinium vesicles bind DNA and they are able to transfect cells in vitro with an efficiency comparable to Lipofectin.

CONCLUSIONS

Based on the intrinsic properties of dequalinium such as the in vivo selectivity for carcinoma cells and selective accumulation in mitochondria we propose DQAsomes as a novel and unique drug and gene delivery system.

Fluorescence and Photochemistry of Recombinant Phytochrome from the Cyanobacterium Synechocystis

Fluorescence and photochemical properties of phytochrome from the cyanobacterium Synechocystis were investigated in the temperature interval from 293 to 85 K. The apoprotein was obtained by overexpression in Escherichia coli and assembled to a holophytochrome with phycocyanobilin (PCB) and phytochromobilin (PφB), Syn(PCB)phy and Syn(PφB)phy, respectively. Its red‐absorbing form, Pr, is characterized at 85 K by the emission and excitation maxima at 682 and 666 nm in Syn(PCB)phy and at 690 and 674 nm in Syn(PφB)phy. At room temperature, the spectra are blue shifted by 5–10 nm. The fluorescence intensity dropped down by ˜15–20‐fold upon warming from 85 to 293 K and activation energy of the fluorescence decay was estimated to be ca 5.4 and 4.9 kJ mol−1 in Syn(PCB)phy and Syn(PφB)phy, respectively. Phototransformation of Pr upon red illumination was observed at temperatures above 160–170 K in Syn(PCB)phy and above 140–150 K in Syn(PφB)phy with a 2–3 nm shift of the emission spectrum to the blue and increase of the intensity of its shorter wavelength part. This was interpreted as a possible formation of the photoproduct of the meta‐Ra type of the plant phytochrome. At ambient temperatures, the extent of the Pr phototransformation to the far‐red‐absorbing form, Pfr, was ca 0.7–0.75 and 0.85–0.9 for Syn(PCB)phy and Syn(PφB)phy, respectively. Fluorescence of Pfr and of the photoproduct similar to lumi‐R was not observed. With respect to the photochemical parameters, Syn(PCB)phy and Syn(PφB)phy are similar to each other and also to a small fraction of phyA (phyA″) and to phyB. The latter were shown to have low photochemical activity at low temperatures in contrast to the major phyA pool (phyA″), which is distinguished by the high extent (ca 50%) of Pr photoransformation at 85 K. These photochemical features are interpreted in terms of different activation barriers for the photoreaction in the Pr excited state.

Timing of removal of the laryngeal mask airway

Previous studies reported that complications associated with removal of the laryngeal mask were more frequent in awake patients than in anaesthetised patients; however, these studies did not comply with the method described in the manufacturer's instruction manual. The reported incidences of regurgitation during the use of the laryngeal mask also differ considerably between studies. We studied these factors in 66 patients in whom the method described in the manual was used. After induction of anaesthesia, the laryngeal mask and a pH probe were inserted and the cuff of the mask was inflated with a minimum volume of air. Anaesthesia was maintained with nitrous oxide and isoflurane in oxygen. At the end of the operation, we randomly allocated patients to one of two groups and the laryngeal mask was removed either while they were still deeply anaesthetised or after they had regained consciousness. No apparent regurgitation occurred in any patient during operation, but one patient in the anaesthetised group regurgitated immediately after removal of the mask. The incidence of complications during or after removal of the laryngeal mask was significantly greater in the anaesthetised group than that in the awake group (p << 0.001; difference [95% CI]: 48.5 [30.5-66.5]%). Therefore, the laryngeal mask can be safely left in place until the patient has regained consciousness after emergence from anaesthesia.

Fluorescence and photochemistry of recombinant phytochrome from the cyanobacterium Synechocystis

Fluorescence and photochemical properties of phytochrome from the cyanobacterium Synechocystis were investigated in the temperature interval from 293 to 85 K. The apoprotein was obtained by overexpression in Escherichia coli and assembled to a holophytochrome with phycocyanobilin (PCB) and phytochromobilin (P phi B), Syn(PCB)phy and Syn(P phi B)phy, respectively. Its red-absorbing form, Pr, is characterized at 85 K by the emission and excitation maxima at 682 and 666 nm in Syn(PCB)phy and at 690 and 674 nm in Syn(P phi B)phy. At room temperature, the spectra are blue shifted by 5-10 nm. The fluorescence intensity dropped down by approximately 15-20-fold upon warming from 85 to 293 K and activation energy of the fluorescence decay was estimated to be ca 5.4 and 4.9 kJ mol-1 in Syn(PCB)phy and Syn(P phi B)phy, respectively. Phototransformation of Pr upon red illumination was observed at temperatures above 160-170 K in Syn(PCB)phy and above 140-150 K in Syn(P phi B)phy with a 2-3 nm shift of the emission spectrum to the blue and increase of the intensity of its shorter wavelength part. This was interpreted as a possible formation of the photoproduct of the meta-Ra type of the plant phytochrome. At ambient temperatures, the extent of the Pr phototransformation to the far-red-absorbing form, Pfr, was ca 0.7-0.75 and 0.85-0.9 for Syn(PCB)phy and Syn(P phi B)phy, respectively. Fluorescence of Pfr and of the photoproduct similar to lumi-R was not observed. With respect to the photochemical parameters, Syn(PCB)phy and Syn(P phi B)phy are similar to each other and also to a small fraction of phyA (phyA") and to phyB. The latter were shown to have low photochemical activity at low temperatures in contrast to the major phyA pool (phyA'), which is distinguished by the high extent (ca 50%) of Pr phototransformation at 85 K. These photochemical features are interpreted in terms of different activation barriers for the photoreaction in the Pr excited state.

Dermatological uses of high-dose intravenous immunoglobulin

High-dose intravenous immunoglobulin (hdIVIg) is increasingly used to treat a range of inflammatory and autoimmune diseases. The current dermatological uses of hdIVIg include the treatment of dermatomyositis and the autoimmune bullous disorders, epidermolysis bullosa acquisita, pemphigoid, and pemphigus. Numerous immunomodulatory mechanisms for hdIVIg have been proposed, and they are discussed alongside treatment protocols and adverse effects. Increasing use of this therapy has helped to establish its excellent safety record, without the many adverse effects of steroids and other immunosuppressive agents. This safety record makes hdIVIg an attractive therapeutic option; however, in view of the time required to administer the infusions, the cost, and the urgent need for controlled trials of hdIVIg in patients with specific dermatological disorders such as pemphigus, patients must be carefully selected. Unfortunately, current dermatological uses of hdIVIg have been limited to either uncontrolled trials or anecdotal case reports, except for a single controlled trial of hdIVIg as adjunctive therapy in patients with dermatomyositis, which documented a significant benefit. Further trials in dermatomyositis should be established to confirm these data and to clarify the dose and frequency of therapy required for patients with dermatomyositis. When using hdIVIg, liaison between the dermatologist and the immunologist is helpful because it allows the use of both the nursing and the medical expertise of an existing immunotherapy unit. If appropriate, the patient may be entered into an hdIVIg home therapy training program, such as the one that exists for primary immunodeficiency and some neurologic indications, with clear benefits in quality of life and inpatient costs.

Impact of tracheotomy on colonization and infection of lower airways in children requiring long-term ventilation: a prospective observational cohort study

STUDY OBJECTIVES

Determination of the following: (1) colonization and infection rates in children requiring long-term ventilation initially via a transtracheal tube and subsequently via a tracheotomy; (2) the number of infection episodes per 1,000 ventilation days, during both types of artificial airways; and (3) routes of colonization/infection of the lower airways, ie, whether the pathogenesis was endogenous (via the oropharynx) or exogenous (via the transtracheal tube or tracheotomy).

DESIGN

Observational, cohort, prospective study over 2 1/2 years.

SETTING

Pediatric ICU (PICU), Royal Liverpool Children's National Health Service Trust of Alder Hey, a tertiary referral center.

PATIENTS

Twenty-two children requiring long-term mechanical ventilation initially transtracheally and subsequently via a tracheotomy.

INTERVENTION

Nil.

RESULTS

The lower airways were colonized in 71% of children during transtracheal ventilation; posttracheotomy, this was 95% (p=0.03). Children developed significantly fewer infections following colonization with a microorganism posttracheotomy (8/15 pretracheotomy vs 6/21 posttracheotomy; p=0.013). Throughout the study, there were a total of 17 episodes of infection, all of which were preceded by colonization. Haemophilus influenzae, Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa were the same four causative pathogens during mechanical ventilation both transtracheally and via tracheotomy. Forty-nine episodes of colonization were observed, 15 pretracheotomy and 34 posttracheotomy; of these, 12 (80%) and 19 episodes (56%), respectively, were primary endogenous, ie, present in the oropharynx on hospital admission and subsequently at tracheotomy. Only one colonization episode (7%) of exogenous pathogenesis was observed during transtracheal intubation, while 12 (35%) (p=0.02) occurred after tracheotomy. An equal number of secondary endogenous colonization episodes (two and three, ie, acquired in the oropharynx after PICU admission and after tracheotomy, respectively, were recorded.

CONCLUSIONS

(1) Despite a high level of hygiene, exogenous colonization without subsequent infection was common. (2) Although all patients were colonized, the infection rate was lower after tracheotomy. This may be due to enhanced immunity (medically stable) and improved tracheobronchial toilet. (3) Microorganisms in children with tracheotomy differ from those in adults.

The anticonvulsant properties of antisense c-fos oligodeoxynucleotides in kainic acid-induced seizures

Evidence has accumulated that the immediate early gene c-fos has important physiological and pharmacological properties in the central nervous system. The role of c-fos in seizures and, in particular, kainic acid-induced seizures, is unclear. It is unknown if c-fos stimulation after kainic acid is a consequence of neuronal activation, or an intrinsic critical component of the metabolic pathways leading to seizure. To elucidate this problem we have pretreated male Wistar rats with antisense c-fos and nonsense c-fos oligodeoxynucleotides 12 h prior to kainic acid 10 mg/kg intraperitoneal. Antisense c-fos inhibited the number of wet dog shakes and the appearance of limbic motor seizures, effects not seen with nonsense or vehicle. The anticonvulsant effects were associated with reduction of both Fos and NGFI-A immunoreactivity and neuroprotection in the hippocampus, thalamus and primary olfactory cortex-amygdaloid region. Four days after antisense c-fos limbic motor seizures were not inhibited, and there was no decrease in Fos or NGFI-A immunoreactivity and no neuroprotection, indicating that the anticonvulsant effects were not secondary to a toxic effect. Sense oligonucleotides had no anticonvulsant effects when given 12 h prior to kainic acid and did not influence immunoreactivity or neuronal survival. In conclusion, these findings suggest a role for c-fos in the generation of kainic acid-induced limbic seizures and neuronal death.

Primary immunodeficiency diseases at Red Cross War Memorial Children's Hospital

OBJECTIVE

To describe the spectrum of primary immunodeficiency diseases (PIDs) diagnosed at Red Cross War Memorial Children's Hospital.

DESIGN

Retrospective, descriptive study.

SETTING

Tertiary, referral hospital.

PATIENTS

All patients investigated by the immunology service because of suspected PIDs, between January 1983 and December 1996.

METHODS

Review of immunology service database and hospital case records.

RESULTS

During the 14-year review period, 515 patients were investigated, a mean of 36.8 new patients per annum. Ninety-three patients with PIDs were diagnosed, a mean of 6.6 new patients per annum. The spectrum of PIDs was similar to that reported in developed countries. As in other series, antibody deficiencies predominated, accounting for 56% (52/93) of diagnoses. The male/female ratio was 1.5:1; 73% (62/85) came from the Western Cape, the remaining 27% (23/85) resided in five other provinces. Eighty per cent (70/87) presented with recurrent or atypical infection, with or without failure to thrive. Sinopulmonary infections (80%), diarrhoeal disease (19%) and candidiasis (18%) were the most common preceding infections. By the age of 5 years, only 60% had been diagnosed, compared with about 80% in developed countries. During the study period, 20% (19/93) were known to have died.

CONCLUSIONS

The results show a pattern of PIDs incidence similar to that in developed countries. Diagnosis was delayed in many patients, which probably contributed to morbidity. To facilitate earlier diagnosis and to improve outcome, children should be considered for an immunological assessment if they exhibit increased susceptibility to infection.

Cell salvage auto transfusion in total knee replacement surgery

We conducted a prospective, randomized study to assess the impact of cell salvage, auto transfusion on the requirements for allogeneic blood for patients undergoing a total knee replacement (TKR). One hundred consecutive TKR patients were randomly allocated to receive either autologous blood (using cell salvage) or an allogeneic blood transfusion as necessary. Patients allocated to the autologous group were rescued with allogeneic blood if the postoperative haemoglobin fell below 9 g dL-1. Forty-two (84%) of 50 patients in the autologous group required no supplementary blood transfusion. Forty (80%) of 50 patients allocated to receive allogeneic blood required transfusion. There were no detrimental effects of autologous blood transfusion. We conclude that autologous blood transfusion, using the cell saver system, is a safe and effective method of reducing the need for allogeneic blood transfusion and, in doing so, reduces the risk of transmission of infections associated with allogeneic blood transfusion, whilst decreasing demand on precious allogeneic blood reserves.

Cytotoxic-T-cell responses, viral load, and disease progression in early human immunodeficiency virus type 1 infection

BACKGROUND

Early in human immunodeficiency virus type 1 (HIV-1) infection there is a decline in viral replication that has been attributed to host immunity, but the components of this response, particularly the ability of cytotoxic T lymphocytes to control viral burden and influence the outcome of disease, are poorly understood.

METHODS

We prospectively studied 33 patients with primary HIV-1 infection for HIV-specific activated cytotoxic T lymphocytes and memory cytotoxic T lymphocytes and compared these lymphocyte responses with changes in viral load and clinical status over the subsequent 18 to 24 months.

RESULTS

Soon after infection, activated HIV-specific cytotoxic T lymphocytes, mediated primarily by CD8+ cells, were detected in 17 of 23 patients (74 percent). Memory cytotoxic T lymphocytes were found in 6 of 6 patients tested (100 percent) during the first three months of infection and in 17 of 21 patients (81 percent) tested during the first six months. The frequencies of memory cytotoxic T lymphocytes varied markedly over time, but overall they declined over the first 6 to 8 months and then stabilized over the next 12 to 18 months. The patients with higher frequencies of Env-specific memory cytotoxic T lymphocytes had a median level of plasma HIV-1 RNA about one third that of the patients with lower frequencies, (median number of RNA copies per milliliter, 22,000 vs. 62,000; P=0.006). Patients with low frequencies of Env-specific memory cytotoxic T lymphocytes (or none) in early infection had a more rapid decline to less than 300 CD4+ cells per cubic millimeter (P = 0.05).

CONCLUSIONS

In early HIV-1 infection, the induction of memory cytotoxic T lymphocytes, particularly those specific for Env, helps control viral replication and is associated with slower declines in CD4+ cell counts. Host cytolytic effector responses appear to delay the progression of HIV-1 disease.

Characterization of recombinant phytochrome from the cyanobacterium Synechocystis

The complete sequence of the Synechocystis chromosome has revealed a phytochrome-like sequence that yielded an authentic phytochrome when overexpressed in Escherichia coli. In this paper we describe this recombinant Synechocystis phytochrome in more detail. Islands of strong similarity to plant phytochromes were found throughout the cyanobacterial sequence whereas C-terminal homologies identify it as a likely sensory histidine kinase, a family to which plant phytochromes are related. An approximately 300 residue portion that is important for plant phytochrome function is missing from the Synechocystis sequence, immediately in front of the putative kinase region. The recombinant apoprotein is soluble and can easily be purified to homogeneity by affinity chromatography. Phycocyanobilin and similar tetrapyrroles are covalently attached within seconds, an autocatalytic process followed by slow conformational changes culminating in red-absorbing phytochrome formation. Spectral absorbance characteristics are remarkably similar to those of plant phytochromes, although the conformation of the chromophore is likely to be more helical in the Synechocystis phytochrome. According to size-exclusion chromatography the native recombinant apoproteins and holoproteins elute predominantly as 115- and 170-kDa species, respectively. Both tend to form dimers in vitro and aggregate under low salt conditions. Nevertheless, the purity and solubility of the recombinant gene product make it a most attractive model for molecular studies of phytochrome, including x-ray crystallography.

Raman spectroscopic and light-induced kinetic characterization of a recombinant phytochrome of the cyanobacterium Synechocystis

A phytochrome-encoding cDNA from the cyanobacterium Synechocystis has been heterologously expressed in Escherichia coli and reconstituted into functional chromoproteins by incubation with either phycocyanobilin (PCB) or phytochromobilin (PPhiB). These materials were studied by Raman spectroscopy and nanosecond flash photolysis. The Raman spectra suggest far-reaching similarities in chromophore configuration and conformation between the Pfr forms of Synechocystis phytochrome and the plant phytochromes (e.g. phyA from oat), but some differences, such as torsions around methine bridges and in hydrogen bonding interactions, in the Pr state. Synechocystis phytochrome (PCB) undergoes a multistep photoconversion reminiscent of the phyA Pr --> Pfr transformation but with different kinetics. The first process resolved is the decay of an intermediate with red-shifted absorption (relative to parent state) and a 25-micros lifetime. The next observable intermediate grows in with 300 (+/-25) micros and decays with 6-8 ms. The final state (Pfr) is formed biexponentially (450 ms, 1 s). When reconstituted with PPhiB, the first decay of this Synechocystis phytochrome is biexponential (5 and 25 micros). The growth of the second intermediate is slower (750 micros) than that in the PCB adduct whereas the decays of both species are similar. The formation of the Pfr form required fitting with three components (350 ms, 2.5 s, and 11 s). H/D Exchange in Synechocystis phytochrome (PCB) delays, by an isotope effect of 2.7, both growth (300 micros) and decay rates (6-8 ms) of the second intermediate. This effect is larger than values determined for phyA (ca. 1.2) and is characteristic of a rate-limiting proton transfer. The formation of the Pfr state of the PCB adduct of Synechocystis phytochrome shows a deuterium effect similar as phyA (ca. 1.2). Activation energies of the second intermediate in the range 0-18 degrees C are 44 (in H2O/buffer) and 48 kJ mol-1 (D2O), with essentially identical pre-exponential factors.

A randomized controlled trial of sedation in the critically ill

A randomized controlled trial comparing: a) a combination of oral chloral hydrate and promethazine to b) a continuous intravenous midazolam infusion, for maintenance sedation in critically ill children, was carried out. The level of sedation was assessed four hourly using a specifically devized sedation scale. Forty-four children entered the study of whom two were subsequently excluded. The number of satisfactory assessments (desired and actual levels of sedation equal) was significantly greater in the chloral hydrate and promethazine group (Chi-squared P < 0.01; confidence intervals of the difference 0.06 to 0.20). The number of assessments at level 5 on the sedation scale (patient restless/ distressed) was significantly greater in the midazolam group (Chi-squared P < 0.05). The total number of satisfactory assessments in the two groups were only 61 and 48% respectively, suggesting that sedation can be considerably improved. Chloral hydrate and promethazine are more effective than midazolam as maintenance sedation in critically ill children. It is possible to prospectively study the efficacy of sedative drugs in critically ill children.

Comparative analysis of the polycystic kidney disease 1 (PKD1) gene reveals an integral membrane glycoprotein with multiple evolutionary conserved domains

PKD1 is the major locus of the common genetic disorder autosomal dominant polycystic kidney disease (ADPKD). Analysis of the predicted protein sequence of the human PKD1 gene, polycystin, shows a large molecule with a unique arrangement of extracellular domains and multiple putative transmembrane regions. The precise function of polycystin remains unclear with a paucity of mutations to define key structural and functional domains. To refine the structure of this protein we have cloned the genomic region encoding the Fugu PKD1 gene. Fugu PKD1 spans 36 kb of genomic DNA and has greater complexity with 54 exons compared with 46 in man. Comparative analysis of the predicted protein sequences shows a lower level of homology than in similar studies with identity of 40 and 59% similarity. However key structural motifs including leucine rich repeats (LRR), a C-type lectin and LDL-A like domains and 16 PKD repeats are maintained. A region of homology with the sea urchin REJ protein was also confirmed in Fugu but found to extend over 1000 amino acids. Several highly conserved intra- and extra-cellular regions, with no known sequence homologies, that are likely to be of functional importance were detected. The likely structure of the membrane associated region has been refined with similarity to the PKD2 protein and voltage gated Ca2+ and Na+ channels highlighted over part of this area. The overall protein structure has therefore been clarified and this comparative analysis derived structure will form the basis for the functional study of polycystin and its individual domains.

Evaluation of gabapentin and S-(+)-3-isobutylgaba in a rat model of postoperative pain

Gabapentin and S-(+)-3-isobutylgaba are anticonvulsant agents that selectively interact with the alpha2delta subunit of voltage-dependent calcium channels. This report describes the activities of these two compounds in a rat model of postoperative pain. An incision of the plantaris muscle of a hind paw induced thermal hyperalgesia and tactile allodynia lasting at least 3 days. Postoperative testing was carried out using the plantar test for thermal hyperalgesia and von Frey hairs for tactile allodynia. A single s.c. dose of gabapentin, 1 h before surgery, dose-dependently (3-30 mg/kg) blocked the development of allodynia and hyperalgesia with a minimum effective dose (MED) of 10 and 30 mg/kg, respectively. The highest dose of gabapentin prevented development of hyperalgesia and allodynia for 24 and 49 h, respectively. Similar administration of S-(+)-3-isobutylgaba also dose-dependently (3-30 mg/kg, s.c.) prevented development of hyperalgesia and allodynia with MED of 3 and 10 mg/kg, respectively. The highest dose of S-(+)-3-isobutylgaba completely blocked development of both nociceptive responses for 3 days. The administration of S-(+)-3-isobutylgaba (30 mg/kg s.c.) 1 h after surgery also completely blocked the maintenance of hyperalgesia and allodynia, but its duration of action was much shorter (3 h). The administration of morphine (1-6 mg/kg s.c.) 0.5 h before surgery prevented the development of thermal hyperalgesia with a MED of 1 mg/kg. However, unlike gabapentin and S-(+)-3-isobutylgaba, it had little effect on the development of tactile allodynia. It is suggested that gabapentin and S-(+)-3-isobutylgaba may be effective in the treatment of postoperative pain.

Gabapentin (neurontin) and S-(+)-3-isobutylgaba represent a novel class of selective antihyperalgesic agents

1. Gabapentin (neurontin) is a novel antiepileptic agent that binds to the alpha 2 delta subunit of voltage-dependent calcium channels. The only other compound known to possess affinity for this recognition site is the (S)-(+)-enantiomer of 3-isobutylgaba. However, the corresponding (R)-(-)-enantiomer is 10 fold weaker. The present study evaluates the activity of gabapentin and the two enantiomers of 3-isobutylgaba in formalin and carrageenan-induced inflammatory pain models. 2. In the rat formalin test, S-(+)-3-isobutylgaba (1-100 mg kg-1) and gabapentin (10-300 mg kg-1) dose-dependently inhibited the late phase of the nociceptive response with respective minimum effective doses (MED) of 10 and 30 mg kg-1, s.c. This antihyperalgesic action of gabapentin was insensitive to naloxone (0.1-10.0 mg kg-1, s.c.). In contrast, the R-(-)-enantiomer of 3-isobutylgaba (1-100 mg kg-1) produced a modest inhibition of the late phase at the highest dose of 100 mg kg-1. However, none of the compounds showed any effect during the early phase of the response. 3. The s.c. administration of either S-(+)-3-isobutylgaba (1-30 mg kg-1) or gabapentin (10-100 mg kg-1), after the development of peak carrageenan-induced thermal hyperalgesia, dose-dependently antagonized the maintenance of this response with MED of 3 and 30 mg kg-1, respectively. Similar administration of the two compounds also blocked maintenance of carrageenan-induced mechanical hyperalgesia with MED of 3 and 10 mg kg-1, respectively. In contrast, R-(-)-3-isobutylgaba failed to show any effect in the two hyperalgesia models. 4. The intrathecal administration of gabapentin dose-dependently (1-100 micrograms/animal) blocked carrageenan-induced mechanical hyperalgesia. In contrast, administration of similar doses of gabapentin into the inflamed paw was ineffective at blocking this response. 5. Unlike morphine, the repeated administration of gabapentin (100 mg kg-1 at start and culminating to 400 mg kg-1) over 6 days did not lead to the induction of tolerance to its antihyperalgesic action in the formalin test. Furthermore, the morphine tolerance did not cross generalize to gabapentin. The s.c. administration of gabapentin (10-300 mg kg-1), R-(-) (3-100 mg kg-1) or S-(+)-3-isobutylgaba (3-100 mg kg-1) failed to inhibit gastrointestinal motility, as measured by the charcoal meal test in the rat. Moreover, the three compounds (1-100 mg kg-1, s.c.) did not generalize to the morphine discriminative stimulus. Gabapentin (30-300 mg kg-1) and S-(+)-isobutylgaba (1-100 mg kg-1) showed sedative/ataxic properties only at the highest dose tested in the rota-rod apparatus. 6. Gabapentin (30-300 mg kg-1, s.c.) failed to show an antinociceptive action in transient pain models. It is concluded that gabapentin represents a novel class of antihyperalgesic agents.

Expression of LIM protein genes Lmo1, Lmo2, and Lmo3 in adult mouse hippocampus and other forebrain regions: differential regulation by seizure activity

The LIM domain is a zinc-binding amino acid motif that characterizes various proteins which function in protein-protein interactions and transcriptional regulation. Expression patterns of several LIM protein genes are compatible with roles in vertebrate CNS development, but little is known about the expression, regulation, or function of LIM proteins in the mature CNS. Lmo1, Lmo2, and Lmo3 are LIM-only genes originally identified as putative oncogenes that have been implicated in the control of cell differentiation and are active during CNS development. Using in situ hybridization for mRNA and immunohistochemical detection of reporter protein expression in transgenic mice, we found that Lmo1, Lmo2, and Lmo3 show individually unique but partially overlapping patterns of expression in several regions of the adult mouse forebrain, including hippocampus, caudate putamen, medial habenula, thalamus, amygdala, olfactory bulb, hypothalamus, and cerebral cortex. In the hippocampal formation, Lmo1, Lmo2, and Lmo3 show different combinatorial patterns of expression levels in CA pyramidal and dentate granule neurons, and Lmo1 is present in topographically restricted subpopulations of astrocytes. Kainic acid-induced limbic seizures differentially regulated Lmo1, Lmo2, and Lmo3 mRNA levels in hippocampal pyramidal and granule neurons, such that Lmo1 mRNA increased, whereas Lmo2 and Lmo3 mRNAs decreased significantly, with maximal changes at 6 hr after seizure onset and return to baseline by 24 hr. These findings show that Lmo1, Lmo2, and Lmo3 continue to be expressed in the adult mammalian CNS in a cell type-specific manner, are differentially regulated by neuronal activity, and may thus be involved in cell phenotype-specific regulatory functions.